US20130005372A1 - Integral thermoelectric generator for wireless devices - Google Patents

Abstract

Electrical power is produced by a first process component, a first heat pipe formed in part by a first cavity within the first process component, and a thermoelectric generator assembly. The thermoelectric generator assembly is thermally coupled on one side to a heat sink and on the other side to the first heat pipe. The first process component is in direct contact with a first process fluid and the first cavity is proximate the first process fluid. The thermoelectric generator assembly produces electrical power.

Description

BACKGROUND
• The present invention relates generally to wireless devices and, more particularly, to powering wireless devices in a wireless field device network.
• Wireless devices are becoming prevalent in industrial applications. As components of wireless field device networks, wireless devices extend the reach of control or process monitoring systems beyond that of wired devices to locations where wiring may be difficult and expensive to provide. A wireless field device network includes a cloud of wireless devices or nodes with a central controller or gateway. The nodes in the wireless network are able to both send and receive information.
• Wireless field device networks are used to control and monitor disparate processes and environments. For example, wireless field device networks may be used in oil fields. An oil field is composed of numerous discrete locations centered on well pads that are scattered over large areas. Communication between these isolated local areas is essential to the overall management of the field. The wireless field device network at a well pad monitors and controls everything from flow rates, well pressure, and fluid temperature to valve status and position and potential leaks. The resulting data is relayed through the network to controllers that analyze the data and actuate control mechanisms in order to manage production or prevent trouble.
• A wireless field device network is a communication network made up of a plurality of wireless devices (i.e., nodes) organized in a wireless topology. Example of wireless topologies include mesh networks, such as, for example, WirelessHART®, and star networks such as, for example, Bluetooth®. In a wireless field device network, a wireless device is one of a wireless transceiver, a wireless data router, and a wireless field device. A wireless transceiver includes a transceiver and an antenna integrated into a single device. A wireless data router includes a wireless transceiver and a data router integrated into a single device. A wireless field device includes a wireless data router and a field device integrated into a single device. A field device is a field-mounted device that performs a function in a control or process monitoring system or plant monitoring system, including all devices used in the measurement, control and monitoring of industrial plants, processes or process equipment, including plant environmental, health and safety devices. A field device typically includes at least one transducer, such as, for example, a sensor or an actuator, and may perform a control or alert function. A wireless transceiver is a device for transmitting and receiving RF-based communication data. A data router is a device that routes data packets received by a wireless transceiver, unpacking the communication payload for consumption by an attached field device (if that device's address matches the final destination address in the packet) or redirecting the communication payload back to the wireless transceiver to be relayed back into the network to the next destination in the logical path. For example, in a wireless mesh network, because each wireless device must be capable of routing messages for itself as well as other devices in the network, each wireless device includes a data router. In contrast, in a simple star network, where wireless devices need only to send and receive messages, wireless devices need not include a data router.
• The use of lower power RF radios is essential for wireless network systems designed for transducer-based applications, such as a wireless field device network. Many devices in the network must be locally-powered because power utilities, such as 120V AC utilities or powered data buses, are not located nearby or are not allowed into hazardous locations where instrumentation and transducers must be located without incurring great installation expense. “Locally-powered” means powered by a local power source, such as a portable electrochemical source (e.g., long-life batteries or fuel cells) or by a low-power energy-scavenging power source (e.g., vibration, solar, or thermoelectric). A common characteristic of local power sources is their limited power capacity, either stored, as in the case of a long-life battery, or produced, as in the case of a solar panel. Batteries are expected to last more than five years and preferably last as long as the life of the product.
SUMMARY
• An embodiment of the present invention includes a first process component, a first heat pipe formed in part by a first cavity within the first process component, and a thermoelectric generator assembly. The thermoelectric generator assembly is thermally coupled on one side to a heat sink and on the other side to the first heat pipe. The first process component is in direct contact with a first process fluid and the first cavity is proximate the first process fluid. The thermoelectric generator produces electrical power.
• Another embodiment of the present invention is a method for generating electrical power for use in a wireless field device network. A process component contacts a process fluid. Heat conducts between the process fluid and a surface of a sealed cavity within the process component. Heat transfers between the surface of a sealed cavity and a thermoelectric generator assembly by the vaporizing and condensing of a working fluid. Heat transfers between the thermoelectric generator assembly and a heat sink by at least one of convection and conduction. Electrical power is generated from the conduction of heat through the thermoelectric generator assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIGS. 1A-1B illustrate a wireless field device incorporating the present invention mounted on a process flange.
• FIGS. 2A-2F illustrate an embodiment of the present invention incorporated into a thermowell for powering a wireless temperature measurement field device.
• FIGS. 3A-3C illustrate another embodiment of the present invention incorporated into a thermowell for powering a wireless temperature measurement field device.
• FIGS. 4A-4C illustrate an embodiment of the present invention incorporated into an averaging pitot tube for powering a wireless flow measurement field device.
• FIGS. 5A-5F illustrate an embodiment of the present invention incorporated into an orifice plate flange for powering a wireless flow measurement field device.
• FIGS. 6A-6E illustrate an embodiment of the present invention incorporated into a steam trap for powering a wireless data router.
• FIGS. 7A-7E illustrate an embodiment of the present invention incorporated into a Venturi tube for powering a wireless flow measurement field device.
• FIGS. 8A-8F illustrate an embodiment of the present invention incorporated into a pump housing for powering a wireless data router.
• FIGS. 9A-9C illustrate an embodiment of the present invention incorporated into an orifice plate for powering a wireless flow measurement field device.
• FIG. 10 illustrates an embodiment of the present invention incorporated into each of two process components for powering a wireless flow measurement field device.
DETAILED DESCRIPTION
• The present invention will be discussed in terms of powering wireless devices in a wireless field device mesh network. A person skilled in the art will recognize that the invention is equally suited to other network topologies and is not limited to solely the embodiments described, but that the invention will include all embodiments falling within the scope of the appended claims.
• The present invention powers wireless devices in a wireless field device network using thermoelectric power generation. As noted above, batteries are expected to last more than five years and preferably last as long as the life of the product. However, in some applications requiring frequent communication, sensing, or actuation, batteries sufficient to provide power for a reasonable length of time are prohibitively large. This is aggravated in severe climates where low temperatures limit battery output or high temperatures limit battery lifetime. In locations where available solar radiation is very limited, for example, near the Arctic Circle, solar panels also must be prohibitively large and expensive to provide the necessary power. Often these applications involve process fluids at temperatures greatly above or below ambient conditions, suggesting the use of thermoelectric power generation. However, thermoelectric power generation is inherently inefficient. Significant improvement in the efficiency of thermoelectric power generation is essential to meet the energy requirements for a wireless device in a wireless field device network.
• The conversion efficiency of a thermoelectric generator is generally less than 1% and is a function of the material and design of the thermoelectric generator. In addition, the amount of heat available to the thermoelectric generator for conversion is greatly reduced by a series of the thermal resistances between the source of the heat (or cold) and the surface of the thermoelectric generator. The thermal resistances slow the transfer of heat for a given cross-sectional area perpendicular to the direction of heat flow, decreasing heat transfer rate per area, or heat flux.
• For example, a typical thermoelectric generator application is a hot fluid in a vessel (e.g., flowing through a pipe or contained within a tank) surrounded by cooler air, with one side of a thermally conductive element attached to an external, uninsulated section of the vessel (strapping it on), and with the other side of the thermally conductive element in physical contact with one surface of a thermoelectric generator. A heat exchanger in contact with the ambient air is attached to the other surface of the thermoelectric generator. There are three significant thermal resistances to the heat flux from the hot fluid in the vessel to the thermoelectric generator: the vessel wall, the physical contact (or lack of physical contact) between the thermally conductive element and the vessel surface, and the thermal resistance through the thermally conductive element.
• Vessel walls are generally made of materials with poor thermal conductivity such as, for example, iron (60 W/mK), stainless steel (10 to 40 W/mK), or Hastelloy (10 W/mK). The heat flux must penetrate the full thickness of the vessel wall to reach the thermally conductive element. Once the heat flux reaches the external vessel wall surface, it must flow into the thermally conductive element. Attachment of such a device to a curved vessel surface, such as a pipe or tank, is fraught with challenges. The radius of curvature of the thermally conductive element must match exactly that of the external vessel surface. Vessel sizes and surface textures vary dramatically making the required precise fit exceptionally difficult. A few point contacts between the two mating surfaces must support virtually the entire heat flow across the area of the mating surfaces, with small air gaps (excellent insulators) occupying the bulk of the interface. The heat flow that does penetrate the vessel wall and cross the interface between the external vessel surface and the thermally conductive element must then conduct through the thermally conductive element to reach the surface of the thermoelectric generator. Thermally conductive elements are typically made of a material with high thermal conductivity, for example, copper (400 W/mK), but still provide another thermal resistance to the heat flow, limiting the heat flux available to the thermoelectric generator. The present invention greatly reduces, or eliminates altogether, all three series thermal resistances to heat flow from a process fluid to a thermoelectric generator, significantly improving the heat flux available for conversion by the thermoelectric generator.
• The present invention provides power to a wireless device in a wireless field device network with a thermoelectric generator. The invention includes a process component directly contacting a process fluid. Process components that directly contact a process fluid include, for example, thermowells, averaging pitot tubes, pipe flanges, orifice plate flanges, steam traps, pressure sensor remote seals, level switches, contacting radar level gauges, vortex flow meters, coriolis meters, magnetic flow meters, turbine meters, valve manifolds, flow straightening elements, flow restrictors, control valves, shut-off valves, filter housings, pump housings, and pressure relief valves. The process component in the present invention contains a heat pipe formed in part by a heat collector cavity internal to the process component. The heat collector cavity is employed solely to form a portion of the heat pipe. The heat pipe couples to one side of the thermoelectric generator and a heat sink couples to the other side of the thermoelectric generator, transferring heat through the thermoelectric generator to generate electrical power for the wireless device. The heat pipe replaces the thermally conductive element describe above, greatly reducing the thermal resistance associated with transferring heat to the surface of the thermoelectric generator. Imbedding the heat pipe within a process component in direct contact with the process fluid eliminates the other two thermal resistances by penetrating the vessel wall directly. The process component does not strap on to the vessel, but penetrates or replaces a section of the vessel wall. Some thermal resistance remains from the need to conduct heat from the process fluid to the heat pipe cavity through the portion of the process component separating the heat collector cavity from the process fluid. However, because the heat flows into the heat pipe from the entire surface area of the heat collector cavity and is transported by the heat of vaporization from the entire internal heat collector cavity surface, the heat flux transported by the heat pipe is much higher.
• FIGS. 1A-1B illustrate an embodiment of the present invention for powering a wireless device in a wireless field device network comprising a thermoelectric generator incorporated into a process component.FIGS. 1A-1B illustrate a process component incorporating the present invention mounted on a process flange.FIG. 1B is a portion ofFIG. 1A enlarged to better illustrate details of the invention.
• FIG. 1A shows process measurement orcontrol point10, includingwireless field device12,process component14,process flange16, process piping20 and wirelessfield device network21. As shown inFIG. 1B,wireless field device12 compriseselectronics housing22, an electronics circuit (not shown),antenna24 and a transducer (not shown).Process component14 is a flange-mounted component comprising a thermoelectric generator assembly (not shown),heat transfer device27,insulation28a,insulation28b, and a heat pipe (not shown).FIG. 1B also shows a plurality offlange bolts18. Although process piping20 is illustrated as a pipe, it may also be any of a number of process vessels including a process tank, storage tank, heat exchanger, boiler, distillation column, kiln, or reactor. Wirelessfield device network21 is any wireless field device network capable of wireless communication withwireless field device12 and of communication with a control or monitoring system. Wirelessfield device network21 is, for example, a wireless field device mesh network.
• Process flange16 is attached (generally welded) to an opening in process piping20 to create a port into process piping20. A sealing gasket (not shown), which is generally composed of material of low thermal conductivity, is inserted between the mating surfaces ofprocess component14 andprocess flange16 beforeprocess component14 is attached to the port to be in direct contact with process fluid F when it flows through process piping20.Process component14 connects to processflange16 with the plurality offlange bolts18. The thermoelectric generator assembly is integrated withprocess component14 and is indirectly in thermal contact with process fluid F. The heat pipe (not shown) thermally connects process fluid F and the thermoelectric generator. The thermoelectric generator assembly is also in thermal contact withheat transfer device27 which is in thermal contact with a heat sink, for example, ambient fluid A. Ambient fluid A surrounds process measurement orcontrol point10 and is typically air. During normal operations, process fluid F and ambient fluid A are at different temperatures.Insulation28aandinsulation28bare positioned to thermally shieldheat transfer device27 in thermal contact with fluid A from portions ofprocess component14 in thermal contact with fluid F. As shown inFIG. 1,process component14 is physically and electrically connected towireless field device12, providing an interface between the process fluid F and the transducer. Alternatively,electronics housing22,antenna24 and the electronics circuitry ofwireless field device12 are physically separate from, but electrically connected to,process component14.
• In operation, a heat flow driven by the temperature difference between process fluid F and ambient fluid A is transported by the heat pipe inprocess component14. In the case where the temperature of process fluid F is higher than the temperature of ambient fluid A, the heat flow is from process fluid F located in process piping20 to the thermoelectric generator assembly by way of the heat pipe. The heat flow is conducted through the thermoelectric generator assembly by the dissipation of the heat into ambient fluid A byheat transfer device27, generating electrical power. The heat flow is in the opposite direction for the case where the temperature of process fluid F is lower than the temperature of ambient fluid A. The electrical power is conducted towireless device12, providing power towireless field device12 for use in operating the transducer and for use in communicating with wirelessfield device network21 throughantenna24. Parallel paths for heat flow between process fluid F and ambient fluid A that would tend to circumvent the intended path through the thermoelectric generator assembly are reduced byinsulation28aandinsulation28b.
• All embodiments described below, except for the embodiment illustrated byFIG. 10, are for the case where the temperature of process fluid F is higher than the temperature of the heat sink and the direction of heat flow is from process fluid F to the heat sink. It is understood that for all subsequently described embodiments, for the case where the temperature of process fluid F is lower than the temperature of the heat sink, the description is the same, with only the direction of heat flow reversed, with heat flowing from the heat sink to process fluid F.
• In all embodiments, a heat sink absorbs or carries away heat to maintain a steady heat flow through the thermoelectric element. For ease of illustration, in all embodiments described below, except for the embodiment illustrated byFIG. 10, the heat sink is ambient fluid A. Ambient fluid A is often air, but it is understood that ambient fluid A may be another type of fluid, such as a cooling fluid, a body of water, or a second process fluid in physical contact with a heat transfer device. In addition, the heat sink may be earth or another large thermal mass, for example, a wall of a building, or an earthen berm.
• Wireless field devices like that described inFIG. 1 can measure any of a number of process characteristics such as, for example, pressure, flow velocity, mass flow, pH, temperature, density, and conductivity; or can monitor process equipment for such things as vibration, strain, or corrosion; or can monitor a general plant environment for such things as fire and gas detection; or can locate the present position of workers and equipment.FIGS. 2A-2F illustrate an embodiment of the present invention for powering a wireless device in a wireless field device mesh network comprising a thermoelectric generator incorporated into a process component for powering a wireless temperature measurement field device, where the process component is a thermowell. A thermowell is a sturdy, protective sheath designed to accommodate and protect a temperature sensor from the harmful effects of a fluid under measurement, including vibration, impact, corrosion, and abrasion. The temperature sensor is inserted into the thermowell along its axis and the thermowell is inserted into a process vessel containing the fluid under measurement. Thermowells also provide an additional advantage of permitting replacement of a failed temperature sensor without having to shut down the process and open up the vessel.
• FIG. 2A shows a cross-section of a thermowell incorporating the present invention.FIG. 2A showsprocess measurement point110, includingwireless field device112, thermowell114,process flange116,flange bolts118 and process piping120 containing process fluid F. A heat sink is provided by ambient fluid A. Ambient fluid A surroundsprocess measurement point110 and is typically air. Although process piping120 is illustrated as a pipe as inFIG. 1, it may also be any of a number of process vessels including a process tank, storage tank, heat exchanger, boiler, distillation column, kiln, or reactor.Wireless field device112 compriseselectronics housing122,electronics circuitry123,antenna124, andtemperature probe130.Temperature probe130 comprisestemperature sensor132 andtemperature sensor wires134.Temperature sensor132 is any sensor that varies an electrical characteristic in response to temperature changes, for example, a thermocouple or an RTD.Temperature sensor wires134 are wires compatible withtemperature sensor132, for example, thermocouple wire.Electronics circuitry123 comprisessensor circuitry136,transmitter communication circuitry138,transceiver140,data router142,power control circuitry144, andenergy storage device146.Sensor circuitry136 processes sensor signals and provides sensor excitation as is known in the art.Transmitter communication circuitry138 comprises communication circuitry for sending and receiving wired signals, for example, HART® data.Transceiver140 is a device for transmitting and receiving RF-based communication data, for example, WirelessHART data.Data router142 is a device that routes data packets.Power control circuitry144 receives incoming power and conditions it as necessary for use by the other components ofelectronics circuitry123.Energy storage device146 stores energy for use by the other components ofelectronics circuitry123 and is, for example, a primary battery, a rechargeable battery, a supercapacitor, or an energy storage capacitor as is known in the art.Thermowell114 is a flange-mounted process component comprisingthermoelectric generator assembly126,heat transfer device127,insulation128a,insulation128b,thermowell cavity148, andheat pipe150.Thermoelectric generator assembly126 comprisesthermoelectric element152,heat spreader154, andpower cable158.Thermoelectric element152 is a device that produces voltage across the device and an electric current through the device (when connected to an electrical load) when opposite sides of the device are held at different temperatures, for example, a semiconductor-based device of a type known in the art made of a series of alternating n-type and p-type semiconductors.Heat spreader154 is a block of high thermal conductivity material, for example, copper, employed to even out the heat flux over the surface ofthermoelectric element152.Heat transfer device127 is any device for efficiently exchanging heat with ambient fluid A. As illustrated,heat transfer device127 is a pin-fin heat exchanger made of a high thermal conductivity material, for example, copper, and is designed with large ratio of surface area to volume to enhance the transfer of heat.Insulation128aandinsulation128bare any type of durable, thermally insulating structures compatible with ambient fluid A. In this embodiment,heat pipe150 includesfill port160, plug162,heat collector cavity164,heat transport pipe166, andheat dissipater cavity168.Plug162 is any plug that seals, for example, a threaded metal plug.Heat collector cavity164 is that portion ofheat pipe150 imbedded within the portion ofthermowell114 that is in direct contact with process fluid F.Heat dissipater cavity168 is that portion ofheat pipe150 that is in direct contact withthermoelectric generator assembly126.Heat transport pipe166 is that portion ofheat pipe150 connectingheat collector cavity164 to heatdissipater cavity168.
• Process flange116 is attached (generally welded) to an opening in process piping120 to create a port into process piping120. A sealing gasket (not shown) is inserted between the mating surfaces ofthermowell114 andprocess flange116 beforethermowell114 is inserted into the port to be in direct contact with process fluid F when it flows through process piping120 as shown inFIG. 2A.Thermowell114 connects to processflange116 at a flanged portion ofthermowell114 with a plurality of flange bolts118 (typically four or more, two shown).Temperature probe130 is inserted intothermowell cavity148 such thattemperature sensor132 is at or near the end ofthermowell114 furthest into process fluidF. Temperature probe130 is generally held in place by a threaded connection near the end oftemperature probe130 opposite that oftemperature sensor132.Temperature sensor wires134connect temperature probe130 toelectronics circuitry123 within electronics housing122 atsensor circuitry136.Antenna124 connects toelectronics circuitry123 within electronics housing122 attransceiver140. Withinelectronics circuitry123,sensor circuitry136 connects totransmitter communication circuitry138.Transmitter communication circuitry138 connects todata router142 which connects totransceiver140.Power control circuitry144 connects toenergy storage device146,sensor circuitry136,transmitter communication circuitry138,data router142, andtransceiver140.Heat pipe150 extends fromheat collector cavity164, described below in reference toFIG. 2D, to heattransport pipe166, described below in reference toFIG. 2F, to heatdissipater cavity168, described below in reference toFIG. 2E. Plug162 seals offfill port160.Heat dissipater cavity168 ofheat pipe150 connects tothermoelectric generator assembly126 atheat spreader154.Heat spreader154 is intimately attached to one side ofthermoelectric element152 andheat transfer device127 is intimately attached to the other side ofthermoelectric element152,opposite heat spreader154.Power cable158 connectsthermoelectric element152 toelectronics housing122 atpower control circuitry144.Insulation128ais positioned in a gap betweenheat transfer device127 and the external surface ofthermowell114, withinsulation128aextending beyond the edges ofheat transfer device127 to insure good thermal isolation.Insulation128bis positioned in the space betweenheat transfer device127 and the flanged portion ofthermowell114 attached to processflange116.Thermowell114 is physically and electrically connected towireless field device112, providing an interface between process fluid F andtemperature probe130. Alternatively,electronics housing122,electronics circuitry123, andantenna124 are physically separate from, but electrically connected to,temperature probe130 andthermowell114.
• In operation,temperature sensor132 varies an electrical characteristic in response to a change in the temperature of process fluid F. The variation in electrical characteristic is conducted viatemperature sensor wires134 tosensor circuitry136.Sensor circuitry136 translates the change in electrical characteristic into a temperature measurement.Sensor circuitry136 sends the temperature measurement totransmitter communication circuitry138 which sends the temperature measurement and any additional information (e.g., wireless field device ID) over a wired link (not shown) todata router142.Data router142 formats the information into a digital data packet along with information on a transmission destination and sends the digital data packet totransceiver140 for transmission into a wireless field device mesh network viaantenna124.
• In addition, as a member of the wireless field device mesh network,wireless field device112 may also route data packets received from the wireless field device mesh network.Transceiver140 receives digital data packets from the wireless field device mesh network viaantenna124 and sends the digital data packets todata router142.Data router142 routes the data packets received bytransceiver140, unpacking the communication payload for consumption bytransmitter communication circuitry138, if the device address ofwireless field device112 matches the final destination address in the packet, or redirecting the digital data packets back totransceiver140 to be relayed back into the network viaantenna124 to the next destination in the logical path.
• At least a portion of the power for the temperature sensing and data transmission described above is supplied in the embodiment of the present invention by the operation ofthermoelectric generator assembly126 with a heat flow efficiently supplied byheat pipe150.Heat collector cavity164 collects heat from process fluid F as described below in reference toFIG. 2D.Heat transport pipe166 transfers the heat fromheat collector cavity164 to heatdissipater cavity168 as described below in reference toFIG. 2F. Atheat dissipater cavity168, heat is transferred intoheat spreader154, (as described below in reference toFIG. 2E) which evens out the heat flux as the heat flow conducts throughheat spreader154 tothermoelectric element152. As the heat flows throughthermoelectric element152, a voltage is generated as a function of the amount of heat flowing throughthermoelectric element152, and current flows towireless field device112. The generation of both a voltage and a current produce electrical power. If heat is not removed from the side oppositeheat spreader154, thermal equilibrium is quickly reached and heat flow ceases along with the power production. Continuous power production requires removing heat from the side of thethermoelectric element152opposite heat spreader154.Heat transfer device127, with its large surface area, efficiently removes heat from the side ofthermoelectric element152opposite heat spreader154 by conduction to ambient fluid A. Ambient fluid A, through convection, conduction or a combination of the two, absorbs or carries away the heat fromheat transfer device127, thus maintaining the steady heat flow throughthermoelectric element152 necessary for continuous power production. In this embodiment,insulation128aandinsulation128breduce heat enteringheat transfer device127 from sources other thanthermoelectric element152 by insulating areas likely to be at a temperature between process fluid F and ambient fluid A, such as exterior surfaces ofthermowell114 and process piping120. This improves the efficiency ofthermoelectric generator assembly126 by limiting the heat to be removed byheat transfer device127 mainly to the heat flowing throughthermoelectric element152. Power produced bythermoelectric element152 is conducted bypower cable158 topower control circuitry144.Power control circuitry144 conditions the power and distributes it as needed tosensor circuitry136,transmitter communication circuitry138,data router142, andtransceiver140 for the temperature sensing and data transmission operations described above. Optionally, power in excess of the immediate requirements for temperature sensing and data transmission operations is stored inenergy storage device146. Power stored inenergy storage device146 is tapped bypower control circuitry144 when temperature sensing and data transmission operation requirements exceed the power immediately available fromthermoelectric generator assembly126, for example, during process start up or shut down when the temperature of process fluid F is lower than during normal process operation.
• According to one embodiment,FIG. 2B is a cross-section of a portion ofthermowell114 that is in direct contact with process fluid F. As shown inFIG. 2B,heat collector cavity164 has a circular cross-section. The tubular shape ofheat collector cavity164 is efficiently created by, for example, drilling. The tubular shape continues throughoutheat pipe150, with the exception ofheat dissipater cavity168.
• FIG. 2C illustrates one embodiment of a shape ofheat dissipater cavity168. The circular cross-section ofheat transfer pipe166 terminates at the edge ofheat dissipater cavity168.Heat dissipater cavity168 is a rectangular cavity matching the rectangular shape ofheat spreader154. This shape is also efficiently created by manufacturing methods know in the art.Heat dissipater cavity168 is comprised of interior surfaces ofthermowell114 on five of six sides and ofheat spreader154 on the remaining side.FIG. 2C further illustrates the shape ofheat transfer device127.Heat transfer device127 wraps partially around the exterior ofthermowell114 to increase the surface area ofheat transfer device127. As mentioned above,insulation128apreferably fills the gap between the portions ofheat transfer device127 that extend beyondthermoelectric element152 and the exterior ofthermowell114.Insulation128aextends beyond the edges ofheat transfer device127 in all directions to insure good thermal isolation from the exterior surfaces ofthermowell114, which are at a temperature between that of process fluid F and ambient fluid A.
• An essential element in the efficient operation of the embodiment shown inFIG. 2A is the operation ofheat pipe150.FIG. 2D illustrates the heat transport mechanism working to transfer heat from process fluid F intoheat pipe150.FIG. 2D is a cross-section of a portion ofheat collector cavity164. In this embodiment,heat pipe150 further comprises workingfluid170 andwicking device172. Workingfluid170 is preferably present inheat pipe150 in both liquid (L) and vapor (V) phases. Workingfluid170 is selected depending on the expected operating temperature range between that of process fluid F and ambient fluid A and is, for example, water, ammonia, methanol, or ethanol. Preferably, wickingdevice172 is a material with sufficiently small pores to exert significant capillary pressure on the liquid phase of workingfluid170 and easily wetted by workingfluid170, for example, sintered ceramic, metal mesh, metal felt, or metal foam. Alternatively, wickingdevice172 comprises grooves in the side ofheat pipe150 running the length ofheat pipe150, sized to provide the required capillary pressure on the liquid phase of workingfluid170.
• According to one embodiment, wickingdevice172 lines the sides ofheat collector cavity164 and contains workingfluid170 in L phase. In operation, heat H from process fluid F flows through the metal walls surroundingheat collector cavity164. Lphase working fluid170 inheat collector cavity164 absorbs the heat flow and changes to Vphase working fluid170 once the absorbed heat reaches the heat of vaporization for workingfluid170. Vphase working fluid170 expands out ofwicking device172 into the interior ofheat collector cavity164, increasing the pressure inheat collector cavity164 and driving Vphase working fluid170 to flow out ofheat collector cavity164 intoheat transport pipe166. Simultaneously, the vaporization of Lphase working fluid170 from wickingdevice172 permits more Lphase working fluid170 to flow intoheat collector cavity164 fromheat transport pipe166 driven by capillary pressure inwicking device172. In this manner, heat flows efficiently from process fluid F into and out ofheat collector cavity164. Although the most efficient heat flow is through the thinnest portion ofthermowell114 separatingheat collector cavity164 from process fluid F, conduction of heat throughout the portion ofthermowell114 in contact with process fluid F provides heat to flow intoheat collector cavity164 from all directions.
• Pursuant to this embodiment,FIG. 2E illustrates the heat transport mechanism working to transfer heat fromheat pipe150 intothermoelectric generator assembly126.FIG. 2E is a cross-section of heat dissipater cavity168 (and connection portion of heat pipe166). Likeheat collector cavity164,heat dissipater cavity168 contains Vphase working fluid170 and is lined withwicking device172, which contains L phase working fluid170 (except for the small region comprising fill plug162). Unlikeheat collector cavity164, workingfluid170 inheat dissipater cavity168 is cooled by the operation ofheat transfer device127. In operation, Vphase working fluid170 in the interior ofheat dissipater cavity168 condenses onto the cooler surfaces ofheat spreader154, changes to Lphase working fluid170 and releases the heat of vaporization absorbed atheat collector cavity164. The released heat H conducts intoheat spreader154 and throughthermoelectric element152 to heattransfer device127. Lphase working fluid170wets wicking device172 and is driven out ofheat dissipater cavity168 intoheat transport pipe166 by capillary pressure inwicking device172. Simultaneously, the condensation of Vphase working fluid170 inheat dissipater cavity168 reduces the pressure inheat dissipater cavity168, providing a pressure differential to drive more Vphase working fluid170 fromheat transport pipe166 intoheat dissipater cavity168. In this manner, heat flows efficiently fromheat pipe150 intothermoelectric generator assembly126.
• FIG. 2F illustrates one embodiment of a heat transport mechanism working to transfer heat collected fromheat collector cavity164, as illustrated inFIG. 2D, to heatdissipater cavity168, as illustrated inFIG. 2E.FIG. 2F is a cross-section of a portion ofheat transport pipe166, which physically and thermally connectsheat collector cavity164 andheat dissipater cavity168. Likeheat collector cavity164 andheat dissipater cavity168,heat transport pipe166 contains Vphase working fluid170 and is lined withwicking device172, which contains Lphase working fluid170.Wicking device172 inheat transport pipe166 connects towicking device172 inheat collector cavity164 andwicking device172 inheat dissipater cavity168 in a continuous fashion such that condensing Lphase working fluid170 fromheat dissipater cavity168 flows throughheat transfer pipe166 to heatcollector cavity164 driven by capillary pressure inwicking device172. Depending on the mounting orientation ofthermowell114, the capillary pressure may work with or against the force of gravity. The capillary pressure inwicking device172 must be sufficient to overcome the pressure differential betweenheat collector cavity164 andheat dissipater cavity168, in addition to the capillary pressure necessary to overcome the force of gravity, to drive a continuous source of Lphase working fluid170 to heatcollector cavity164. The interior ofheat transfer pipe166 connects to the interiors ofheat collector cavity164 andheat dissipater cavity168 in a continuous fashion such that Vphase working fluid170 flows through the interior ofheat transport pipe166 fromheat collector cavity164 to heatdissipater cavity168 driven by the pressure differential caused by the vaporization of Lphase working fluid170 inheat collector cavity164 and the condensation of Vphase working fluid170 inheat dissipation cavity168.
• Pursuant to one embodiment, thermowell114 is ideally assembled at a factory under precisely controlled conditions, ensuring consistent, reliable operation. This is in contrast to strapping or otherwise mounting a thermoelectric generator onto a vessel out in the field.Heat pipe150 is preferably sealed under partial vacuum sufficient to maintain an internal pressure near the vapor pressure of workingfluid170 and to remove non-condensing gases, the presence of which would impede the flow of Vphase working fluid170 and reduce the efficiency ofheat pipe150. Workingfluid170 is loaded intoheat pipe150 throughfill port160 and sealed under partial vacuum withplug162, as shown inFIG. 2A.
• The embodiment of the present invention shown inFIGS. 2A-2F greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within a thermowell in direct contact with a process fluid. By penetrating the vessel wall directly, the problem of thermal resistance through the vessel wall is eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the vessel wall. Also, because the heat flows intoheat pipe150 from the entire surface area ofheat collector cavity164 and is transported by the heat of vaporization from the entire internal heat collector cavity surface, the heat transported byheat pipe150 can be extremely high. Ultimately, the amount of heat transported is dependant on the area ofheat collector cavity164, the size and efficiency ofheat transfer device127, and the difference in temperature between ambient fluid A and process fluid F. Finally, because the entire unit can be assembled and tested under carefully controlled conditions at a factory, performance is more consistent and efficient.
• The tubular heat collector cavity shape illustrated inFIGS. 2A-2F is one of many possible shapes employed depending on the process component and the amount of power to be generated.FIGS. 3A-3C illustrate another embodiment of the present invention incorporated into a thermowell for powering a wireless temperature measurement field device. InFIGS. 3A-3C, a cylindrical shaped heat collector cavity is combined with a thermoelectric generator assembly containing two thermoelectric elements. The larger heat collector cavity, with its increased surface area, supplies much greater heat flow than the embodiment ofFIGS. 2A-2F. A significantly larger heat transfer device is also needed to support the greater heat flow. The greater heat flowing through the two thermoelectric elements produces significantly more power than the embodiment ofFIGS. 2A-2F. The additional power is useful for wireless devices where, for example, more frequent transmissions are desired. The additional power is also useful for powering other elements of the wireless field device network, for example, a central controller, a gateway; a remote telemetry unit or a backhaul radio that connects a gateway to a higher-level network or host computer.
• FIG. 3A shows a cross-section of another embodiment of the present invention incorporated into a thermowell for powering a wireless temperature measurement field device. Most of the components of the embodiment ofFIG. 3A are identical to those described in reference toFIG. 2A-2F with reference numbers differing by 100.FIG. 3A showsprocess measurement point210, includingwireless field device212, thermowell214,process flange216,flange bolts218 and process piping220 containing process fluid F. A heat sink is provided by ambient fluid A.Wireless field device212 is identical towireless field device112 described above.Thermowell214 is a flange-mounted process component comprisingthermoelectric generator assembly226,heat transfer device227,insulation228a,insulation228b,thermowell cavity248, andheat pipe250.Thermoelectric generator assembly226 comprises twothermoelectric elements252, twoheat spreaders254, and twopower cables258.Thermoelectric elements252 are identical tothermoelectric element152 described above. As illustrated,heat transfer device227 is identical to heattransfer device127 described above, except that it completely encirclesthermowell214.Heat pipe250 comprises twofill ports260, twoplugs262,heat collector cavity264,heat transport pipe266, and twoheat dissipater cavities268.Heat pipe250 also comprises a wicking device (not shown) and a working fluid present in both liquid and vapor phases (not shown); both wicking device and working fluid are as described above in reference toFIGS. 2D-2F. Employing two fillports260 on opposites ofheat pipe250 provides for more efficient loading of the working fluid.Heat collector cavity264 is that portion ofheat pipe250 imbedded within the portion ofthermowell214 that is in direct contact with process fluid F.Heat dissipater cavities268 are those portions ofheat pipe250 that are in direct contact withthermoelectric generator assembly226.Heat transport pipe266 is that portion ofheat pipe250 connectingheat collector cavity264 to heatdissipater cavities268. Connections and operations of the embodiment shown inFIG. 3A are as described above in reference toFIG. 2A, with component numbers increased by 100.
• FIG. 3B is a cross-section of a portion ofthermowell214 that is in direct contact with process fluid F. As shown inFIG. 3B,heat collector cavity264 has a cylindrical cross-section. The cylindrical shape ofheat collector cavity264 is efficiently created by manufacturing methods known in the art. In this embodiment, the cylindrical shape continues throughoutheat pipe250, with the exception ofheat dissipater cavities268.
• FIG. 3C is a cross-section of a portion ofthermowell214 containingheat dissipater cavities268. The cylindrical cross-section ofheat transfer pipe266 terminates at the junction withheat dissipater cavities268.Heat dissipater cavities268 are identical to heatdissipater cavity168 described above.FIG. 3C further illustrates the shape ofheat transfer device227.Heat transfer device227 wraps completely around the exterior ofthermowell214. As with embodiments described above,insulation228afills the gap between the portions ofheat transfer device227 that extend beyondthermoelectric elements252 and the exterior ofthermowell214.Insulation228aextends beyond the edges ofheat transfer device227 to insure good thermal isolation from the exterior surfaces ofthermowell214.
• The embodiment of the present invention shown inFIGS. 3A-3C greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within a thermowell in direct contact with a process fluid. This embodiment, in addition to all of the advantages described for embodiments above, is able to produce significantly more power by increasing the size of both the heat pipe and the thermoelectric generator assembly. Although the embodiment is shown with two thermoelectric elements, it is understood that additional thermoelectric elements can be added to produce additional power, so long as sufficient heat flow is produced.
• As mentioned above, wireless field devices like that described inFIG. 1 can measure any of a number of process characteristics such as, for example, pressure, flow velocity, mass flow, pH, temperature, density, and conductivity; or can monitor process equipment for such things as vibration, strain, or corrosion; or can monitor a general plant environment for such things as fire and gas detection; or can locate the present position of workers and equipment.FIGS. 4A-4C illustrate an embodiment of the present invention for powering a wireless device in a wireless field device mesh network with a thermoelectric generator incorporated into a process component, where the process component is an averaging pitot tube and the wireless device is a wireless flow measurement field device. An averaging pitot tube such as, for example, the Rosemount® 485 Annubar, measures flow velocity by sensing ram (high) and static (low) pressures caused by the fluid flowing past the pitot tube. Increasing flow velocity produces a larger difference between the two pressures. The two pressures transmit through ports and plenums in the pitot tube to a differential pressure sensor which directly measures the difference between the two pressures.
• FIG. 4A shows a cross-section of an averaging pitot tube incorporating one embodiment of the present invention.FIG. 4A showsprocess measurement point310, includingwireless field device312, averagingpitot tube314,process flange316,flange bolts318 and process piping320 containing process fluid F. A heat sink is provided by ambient fluid A. Ambient fluid A surroundsprocess measurement point310 and is typically air. Although process piping320 is illustrated as a pipe as inFIG. 1, it may also be any of a number of process vessels including a process tank, storage tank, heat exchanger, boiler, distillation column, kiln, or reactor.Wireless field device312 compriseselectronics housing322,electronics circuitry323,antenna324, and differential pressure (DP)sensor330.DP sensor330 is any sensor or sensors that vary an electrical characteristic ,in response to changes in the difference between two simultaneously sensed pressures such as, for example, the Rosemount 3051 S pressure transmitter.Electronics circuitry323 comprisessensor circuitry336,transmitter communication circuitry338,transceiver340,data router342,power control circuitry344, andenergy storage device346.Sensor circuitry336 processes sensor signals and provides sensor excitation as is known in the art.Transmitter communication circuitry338 comprises communication circuitry for sending and receiving wired signals.Transceiver340 is a device for transmitting and receiving RF-based communication data.Data router342 is a device that routes data packets.Power control circuitry344 receives incoming power and conditions it as necessary for use by the other components ofelectronics circuitry323.Energy storage device346 stores energy for use by the other components ofelectronics circuitry323 and is, for example, a primary battery, a rechargeable battery, a supercapacitor, or an energy storage capacitor as is known in the art. Averagingpitot tube314 is a flange-mounted process component comprisingthermoelectric generator assembly326,heat transfer device327,insulation328a,insulation328b,high pressure plenum332,low pressure plenum334, andheat pipe350.Thermoelectric generator assembly326 comprisesthermoelectric element352,heat spreader354, andpower cable358.Thermoelectric element352 is a device that produces voltage across the device and an electric current through the device (when connected to an electrical load) when opposite sides of the device are held at different temperatures, for example, a semiconductor-based device of a type known in the art made of a series of alternating n-type and p-type semiconductors.Heat spreader354 is a block of high thermal conductivity material, for example, copper, employed to even out the heat flux over the surface ofthermoelectric element352.Heat transfer device327 is any device for efficiently exchanging heat with ambient fluid A. As illustrated,heat transfer device327 is a pin-fin heat exchanger made of a high thermal conductivity material, for example, copper, and is designed with large ratio of surface area to volume to enhance the transfer of heat.Insulation328aandinsulation328bare any type of durable, thermally insulating structure compatible with ambient fluidA. Heat pipe350 comprisesfill port360, plug362,heat collector cavity364,heat transport pipe366, andheat dissipater cavity368.Heat collector cavity364 is that portion ofheat pipe350 imbedded within the portion of averagingpitot tube314 that is in direct contact with process fluid F.Heat dissipater cavity368 is that portion ofheat pipe350 that is in direct contact withthermoelectric generator assembly326.Heat transport pipe366 is that portion ofheat pipe350 connectingheat collector cavity364 to heatdissipater cavity368.Heat pipe350 further comprises a wicking device (not shown) and a working fluid present in both liquid and vapor phases (not shown); both wicking device and working fluid are as described above in reference toFIGS. 2D-2F.
• Process flange316 is attached (generally welded) to an opening in process piping320 to create a port into process piping320. A sealing gasket (not shown) is inserted between the mating surfaces of averagingpitot tube314 andprocess flange316 before averagingpitot tube314 is inserted into the port to be in direct contact with process fluid F when it flows through process piping320 as shown inFIG. 4A. Averagingpitot tube314 connects to processflange316 at a flanged portion of averagingpitot tube314 with a plurality of flange bolts318 (typically four or more, two shown).DP sensor330 is attached to averagingpitot tube314 such that a pressure inhigh pressure plenum332 and a pressure inlow pressure plenum334 are simultaneously sensed byDP sensor330.DP sensor330 connects toelectronics circuitry323 within electronics housing322 atsensor circuitry336.Antenna324 connects toelectronics circuitry323 within electronics housing322 attransceiver340. Withinelectronics circuitry323,sensor circuitry336 connects totransmitter communication circuitry338.Transmitter communication circuitry338 connects todata router342 which connects totransceiver340.Power control circuitry344 connects toenergy storage device346,sensor circuitry336,transmitter communication circuitry338,data router342, andtransceiver340.Heat pipe350 extends fromheat collector cavity364 to heatdissipater cavity368 withheat transport pipe366 connectingheat collector cavity364 to heatdissipater cavity368. Plug362 seals offfill port360 after the working fluid is loaded intoheat pipe350 under partial vacuum.Heat dissipater cavity368 ofheat pipe350 connects tothermoelectric generator assembly326 atheat spreader354.Heat spreader354 is intimately attached to one side ofthermoelectric element352 andheat transfer device327 is intimately attached to the other side ofthermoelectric element352,opposite heat spreader354.Power cable358 connectsthermoelectric element352 toelectronics circuitry323 within electronics housing322 atpower control circuitry344.Insulation328ais positioned in a gap betweenheat transfer device327 and the external surface of averagingpitot tube314, withinsulation328aextending beyond the edges ofheat transfer device327 to insure good thermal isolation. Likewise,insulation328bis positioned in the space betweenheat transfer device327 and the flanged portion of averagingpitot tube314 attached to processflange316.
• In operation,DP sensor330 varies an electrical characteristic in response to changes in the difference between a pressure inhigh pressure plenum332 and a pressure inlow pressure plenum334, the two pressures resulting from the flow of process fluid F past averagingpitot tube314 as conducted by separate ports in the pitot tube tohigh pressure plenum332 andlow pressure plenum334. The variation in electrical characteristic is translated bysensor circuitry336 into a flow measurement.Sensor circuitry336 sends the flow measurement totransmitter communication circuitry338 which sends the flow measurement and any additional information (e.g., wireless field device ID) over a wired link (not shown) todata router342.Data router342 formats the information into a digital data packet along with information on a transmission destination and sends the digital data packet totransceiver340 for transmission into a wireless field device mesh network viaantenna324.
• In addition, as a member of the wireless field device mesh network,wireless field device312 routes data packets received from the wireless field device mesh network.Transceiver340 receives digital data packets from the wireless field device mesh network viaantenna324 and sends the digital data packets todata router342.Data router342 routes the data packets received bytransceiver340, unpacking the communication payload for consumption bytransmitter communication circuitry338, if the device address ofwireless field device312 matches the final destination address in the packet, or redirecting the digital data packets back totransceiver340 to be relayed back into the network viaantenna324 to the next destination in the logical path.
• At least a portion of the power for the flow measurement and data transmission described above is supplied in the embodiment of the present invention by the operation ofthermoelectric generator assembly326 with a heat flow efficiently supplied byheat pipe350.Heat collector cavity364 collects heat from process fluid F.Heat transport pipe366 transfers the heat fromheat collector cavity364 to heatdissipater cavity368. Atheat dissipater cavity368, heat is transferred intoheat spreader354, which evens out the heat flux as the heat flow conducts throughheat spreader354 tothermoelectric element352. As the heat flows through thermoelectric element352 a voltage and a current are generated as a function of the amount of heat flowing throughthermoelectric element352. The generation of both a voltage and a current produce power which is consumed bywireless field device312 as needed.Heat transfer device327, with its large surface area, efficiently removes heat from the side ofthermoelectric element352opposite heat spreader354 by conduction to ambient fluid A. Ambient fluid A, through convection, conduction or a combination of the two, absorbs or carries away the heat, thus maintaining the steady heat flow throughthermoelectric element352 necessary for continuous power production.Insulation328aandinsulation328breduce heat enteringheat transfer device327 from sources other thanthermoelectric element352 by insulating areas likely to be at a temperature between process fluid F and ambient fluid A, such as exterior surfaces of averagingpitot tube314. This improves the efficiency ofthermoelectric generator assembly326 by limiting the heat to be removed byheat transfer device327 to the heat flowing throughthermoelectric element352. Power produced bythermoelectric element352 is conducted bypower cable358 topower control circuitry344.Power control circuitry344 conditions the power and distributes it as needed tosensor circuitry336,transmitter communication circuitry338,data router342, andtransceiver340 for the flow measurement and data transmission operations described above. Optionally, power in excess of the immediate requirements for flow measurement and data transmission operations is stored inenergy storage device346. Power stored inenergy storage device346 is tapped bypower control circuitry344 when flow measurement and data transmission operation requirements exceed the power immediately available fromthermoelectric generator assembly326, for example, during process start up or shut down when the temperature of process fluid F is lower than during normal process operation.
• FIG. 4B is a cross-section of a portion of averagingpitot tube314 that is in direct contact with process fluid F.High pressure plenum332 opens to ram (high) pressure,low pressure plenum334 opens to static (low) pressure, andheat collector cavity364 has a closed circular cross-section. In this embodiment, the tubular shape ofheat collector cavity364 continues throughoutheat pipe350, with the exception ofheat dissipater cavity368.
• FIG. 4C illustrates the shape ofheat dissipater cavity368 according to this embodiment. The circular cross-section ofheat transfer pipe366 terminates at the edge ofheat dissipater cavity368.Heat dissipater cavity368 is a rectangular cavity matching the rectangular shape ofheat spreader354. This shape is also efficiently created by manufacturing methods know in the art.Heat dissipater cavity368 is comprised of interior surfaces of averagingpitot tube314 on five of six sides and ofheat spreader354 on the remaining side.FIG. 4C further illustrates the shape ofheat transfer device327.Heat transfer device327 wraps partially around the exterior of averagingpitot tube314 to increase the surface area ofheat transfer device327. As mentioned above,insulation328afills the gap between the portions ofheat transfer device327 that extend beyondthermoelectric element352 and the exterior of averagingpitot tube314.Insulation328aextends beyond the edges ofheat transfer device327 in all directions to insure good thermal isolation from the exterior surfaces of averagingpitot tube314, which are at a temperature between that of process fluid F and ambient fluid A.
• The embodiment of the present invention shown inFIGS. 4A-4C greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within an averaging pitot tube in direct contact with a process fluid. By penetrating the vessel wall directly, the problem of thermal resistance through the vessel wall is eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the vessel wall. Also, because the heat flows intoheat pipe350 from the entire surface area ofheat collector cavity364 and is transported by the heat of vaporization from the entire internal heat collector cavity surface, heat can be very efficiently transported byheat pipe350.
• The embodiments of the present invention described above comprise process components connected to a vessel by a process flange. Alternative embodiments of the present invention connect to a vessel by other than a process flange, for example, a threaded connection or a welded connection.
• FIGS. 5A-5F illustrate yet another embodiment of the present invention for powering a wireless device in a wireless field device mesh network with a thermoelectric generator incorporated into a process component, where the process component is an orifice plate flange and the wireless device is a wireless flow measurement field device. In contrast to the embodiments described above, this embodiment replaces a section of process piping through which a process fluid (or process fluid by-product) flows, instead of attaching to an external opening in a process vessel. Orifice plate flanges such as those found in, for example, a Rosemount® 1496 Flange Union, include pressure taps for transmitting fluid pressure to a DP sensor. Two such orifice plate flanges comprise the flange union, with each orifice plate flange employing a pressure tap to transmit the fluid pressure in the pipe to the DP sensor via an impulse line. An orifice plate, for example, a Rosemount® 1495 Orifice Plate, positioned between the two orifice plate flanges causes a pressure drop across the orifice plate as the fluid is forced to flow through the orifice, resulting in two different fluid pressures being transmitted to the DP sensor. This pressure difference is a function of flow velocity through the pipe. An increase in flow velocity produces a larger difference between the two pressures. The two pressures transmit through the pressure taps and impulse lines to the DP sensor which directly measures the difference between the two pressures.
• FIG. 5A illustrates one embodiment of a process component incorporating the present invention where the process component is an orifice plate flange.FIG. 5A shows process measurement orcontrol point410, including wireless flowmeasurement field device412,orifice plate flange414,orifice plate415,orifice plate flange416, stud/nuts418 and process piping420 containing process fluid F. A heat sink is provided by ambient fluid A. Ambient fluid A surroundsprocess measurement point410 and is typically air. Wireless flowmeasurement field device412 compriseselectronics housing422,electronics circuitry423,antenna424, differential pressure (DP)sensor430, high-side (upstream)impulse line432, and low-side (downstream)impulse line434.Impulse line432 andimpulse line434 are typically metal pipes chemically compatible with process fluid F, for example, stainless steel.Electronics circuitry423 is as described above in reference toFIG. 4A with reference numbers increased by 100.Orifice plate flange414 is an in-line process component comprising high-side pressure tap433, thermoelectric generator assembly426 (shown inFIG. 5B),heat transfer device427,insulation428, and heat pipe450 (shown inFIG. 5B).Thermoelectric generator assembly426 comprisespower cable458.Orifice plate flange416 is an in-line process component comprising low-side pressure tap435. Together,orifice plate flange414,orifice plate415,orifice plate flange416, studs/nuts418, and sealing gaskets (not shown) comprise an orifice plate flange union.
• Orifice plate flange414 andorifice plate flange416 are attached to process piping420 at points W by, for example, welding.Orifice plate415 is inserted betweenorifice plate flange414 andorifice plate flange416 with a first sealing gasket betweenorifice plate415 andorifice plate flange414 and a second sealing gasket betweenorifice plate415 andorifice plate flange416.Orifice plate flange414,orifice plate415,orifice plate flange416, and the two gaskets are bolted together by a plurality of stud/nuts418.Thermoelectric generator assembly426 is integrated withorifice plate flange414 and is in thermal contact with process fluid F and ambientfluid A. Insulation428 is positioned to thermally shieldheat transfer device427 in thermal contact with fluid A from portions oforifice plate flange414 in thermal contact with process fluidF. Impulse line432 connects to orificeplate flange414 atpressure tap433 by, for example, a threaded connection. Similarly,impulse line434 connects to pressuretap435.Impulse line432 andimpulse line434connect pressure tap433 andpressure tap435, respectively, toDP sensor430, physically connecting wireless flowmeasurement field device412 to orificeplate flange414 andorifice plate flange416, respectively.DP sensor430 connects toelectronics circuitry423 within electronics housing422 atsensor circuitry436. Connections withinelectronics housing422 are as described above with respect toFIG. 4A.
• In operation, high-side impulse line432 and low-side impulse line434 transmit process pressures toDP sensor430.DP sensor430 varies an electrical characteristic in response to changes in the difference between the pressure in high-side impulse line432 and the pressure in low-side impulse line434, the two pressures resulting from the restricted flow of process fluid F through the orifice plate. The variation in electrical characteristic is translated bysensor circuitry436 into a flow measurement.
• At least a portion of power for the flow measurement and data transmission described above is supplied to wireless flowmeasurement field device412 in the embodiment of the present invention by the operation ofthermoelectric generator assembly426 with a heat flow efficiently supplied byheat pipe450 as described above in reference toFIG. 4A with reference numbers increased by 100 and illustrated inFIGS. 5B-5F. A heat flow driven by the temperature difference between process fluid F and ambient fluid A is transported byheat pipe450 inorifice plate flange414. The heat flow is conducted throughthermoelectric generator assembly426 by the dissipation of the heat into ambient fluid A byheat transfer device427, generating electrical power.
• FIG. 5B is a cross-section oforifice plate flange414 illustratingthermoelectric generator assembly426,heat transfer device427,insulation428, andheat pipe450.FIG. 5C is a portion ofFIG. 5B enlarged to better illustrate the details ofthermoelectric generator assembly426,heat transfer device427,insulation428, and a portion ofheat pipe450.FIG. 5C shows primarily an extended portion oforifice plate flange414 attached to the main, flange portion oforifice plate flange414 by, for example, a threaded connection (as shown) or a welded connection. The extended portion oforifice plate flange414 serves to provide spatial separation for improved thermal isolation, in addition to the thermal shielding ofinsulation428, betweenheat transfer device427 in thermal contact with fluid A and portions oforifice plate flange414 in thermal contact with process fluid F. As illustrated,heat transfer device427 is a pin-fin heat exchanger made of a high thermal conductivity material, for example, copper, and is designed with large ratio of surface area to volume to enhance the transfer of heat.
• As shown inFIGS. 5B-5C,thermoelectric generator assembly426 comprisesthermoelectric element452,heat spreader454, andpower cable458.Thermoelectric element452 andheat spreader454 are as described in reference toFIG. 4A, with reference numbers differing by 100.Heat pipe450 comprisesfill port460, plug462,heat collector cavity464,heat transport pipe466, andheat dissipater cavity468.Heat collector cavity464 is that portion ofheat pipe450 imbedded within the portion oforifice plate flange414 that is in direct contact with process fluid F.Heat dissipater cavity468 is that portion ofheat pipe450 that is in direct contact withthermoelectric generator assembly426.Heat transport pipe466 is that portion ofheat pipe450 connectingheat collector cavity464 to heatdissipater cavity468.Heat pipe450 further comprises a wicking device (not shown) and a working fluid present in both liquid and vapor phases (not shown); both wicking device and working fluid are as described above in reference toFIGS. 2D-2F.
• Heat pipe450 extends fromheat collector cavity464 to heatdissipater cavity468 withheat transport pipe466 connectingheat collector cavity464 to heatdissipater cavity468.Heat dissipater cavity468 ofheat pipe450 connects tothermoelectric generator assembly426 atheat spreader454.Heat spreader454 is intimately attached to one side ofthermoelectric element452 andheat transfer device427 is intimately attached to the other side ofthermoelectric element452,opposite heat spreader454.Power cable458 connectsthermoelectric element452 toelectronics circuitry423 within electronics housing422 at power control circuitry444 (shown inFIG. 5A).Insulation428 is positioned in a gap betweenheat transfer device427 and the external surface oforifice plate flange414, extending beyond the edges ofheat transfer device427 to insure good thermal isolation betweenheat transfer device427 and the flange portion oforifice plate flange414.
• As illustrated inFIG. 5B,heat collector cavity464 extends along much of a portion oforifice plate flange414 that is proximate process fluid F.FIG. 5D is a cross-section oforifice plate flange414 showing the cylindrical shape ofheat collector cavity464. This shape surrounds process fluid F and provides a large surface area for heat transfer from process fluid F intoheat pipe450.
• FIG. 5E is another cross-section oforifice plate flange414.FIG. 5E illustratesorifice plate flange414 rotated 90 degrees fromFIG. 5B. In addition to the identically numbered elements inFIG. 5B,FIG. 5E shows highside pressure tap433 and plurality of bolt holes474.Heat transfer device427 extends significantly beyondthermoelectric element452 to provide a large ratio of surface area to volume to enhance the transfer of heat with ambientfluid A. Insulation428 is positioned in the gap betweenheat transfer device427 and the external surface oforifice plate flange414, extending well beyond the edges ofheat transfer device427 to insure good thermal isolation betweenheat transfer device427 and both the flange and extended portions oforifice plate flange414.
• FIG. 5F is another cross-section oforifice plate flange414 in an axial plane 90 degrees fromFIG. 5B.FIG. 5F shows highside pressure tap433 andheat collector cavity464 ofheat pipe450. As shown inFIGS. 5B, and5E-5F,heat pipe450 is completely separate from, and does not interfere with the functioning of, highside pressure tap433.
• Although the embodiment ofFIG. 5A is described withorifice plate flange414 positioned in the upstream location, it is understood that an orifice plate flange incorporating the present invention functions as well when alternatively positioned in the downstream location. In addition, although the embodiment ofFIG. 5A shows only orificeplate flange414 incorporating the present invention to supply power to wireless flowmeasurement field device412, it is understood thatorifice plate flange416 may also include the present invention in a fashion identical to orificeplate flange414. Such an arrangement increases the power to wireless flowmeasurement field device412 for applications requiring, for example, more frequent communications with the wireless field device mesh network. The additional power is also useful for powering other elements of the wireless field device network, for example, a central controller, a gateway; a remote telemetry unit or a backhaul radio that connects a gateway to a higher-level network or host computer.
• The embodiment of the present invention shown inFIGS. 5A-5F greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within an orifice plate flange in direct contact with a process fluid. By penetrating the vessel wall directly, the problem of thermal resistance through the vessel wall is eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the vessel wall. Also, because the heat flows intoheat pipe450 from the entire surface area ofheat collector cavity464 and is transported by the heat of vaporization from the entire internal heat collector cavity surface, the heat flux transported byheat pipe450 is extremely high.
• FIGS. 6A-6E illustrate yet another embodiment of the present invention for powering a wireless device in a wireless field device mesh network with a thermoelectric generator incorporated into a process component, where the process component is a steam trap and the wireless device is a wireless data router. Like the embodiment described in reference toFIGS. 5A-5D, this embodiment replaces a section of process piping through which a process fluid (or process fluid by-product) flows, instead of attaching to an external opening in a process vessel.FIG. 6A illustrates a process component incorporating the present invention where the process component is a steam trap.Steam trap514 is attached to process piping carrying primarily steam,steam line516, at measurement orcontrol point510. Measurement orcontrol point510 is a location where water condensing from the steam naturally collects. Measurement Or controlpoint510 includeswireless data router512. The condensate water is a process fluid by-product resulting from heat losses fromsteam line516 into the ambient environment.Steam trap514 contains a device that permits the condensate water to flow out ofsteam line516 and into process piping for draining condensate water,condensate line520, while controlling, and largely preventing, the escape of steam intocondensate line520.
• FIGS. 6B-6E illustrate howsteam trap514 shown inFIG. 6A embodies the present invention.FIG. 6B shows process measurement orcontrol point510, includingwireless data router512,steam trap514,steam line516 andcondensate line520.Wireless data router512 compriseselectronics housing522,electronics circuitry523, andantenna524.Electronics circuitry523 comprisestransceiver540,data router542,power control circuitry544, andenergy storage device546.Steam trap514 comprises thermoelectric generator assembly526 (shown inFIG. 6E),heat transfer device527,insulation528,steam trap bolts518, and heat pipe550 (shown inFIGS. 6C-6E).Thermoelectric generator assembly526 comprisespower cable558. As illustrated,heat transfer device527 is a pin-fin heat exchanger.
• Steam trap514 is attached by, for example, threaded connections, to steamline516 andcondensate line520.Thermoelectric generator assembly526 is integrated withsteam trap514 and is in thermal contact with steam/condensate F and ambient fluid A. Steam/condensate F is a mixture of steam and condensate. A heat sink is provided by ambient fluid A. Steam/condensate F and ambient fluid A are at different temperatures.Power cable558 connectsthermoelectric generator assembly526 toelectronics circuitry523 within electronics housing522 atpower control circuitry544.
• In operation,steam trap514 permits condensate water fromsteam line516 to flow out ofsteam line516 and intocondensate line520, as explained below in reference toFIG. 6C.Wireless data router512 routes data packets received from a wireless field device mesh network. At least a portion of the power for this data transmission is supplied towireless data router512 in the embodiment of the present invention by the operation ofthermoelectric generator assembly526 with a heat flow efficiently supplied byheat pipe550 as described in detail inFIGS. 6C-6E below. A heat flow driven by the temperature difference between steam/condensate F and ambient fluid A is transported by heat pipe550 (shown inFIGS. 6C-6E) insteam trap514. The heat flow is conducted throughthermoelectric generator assembly526 by the dissipation of the heat into ambient fluid A byheat transfer device527, generating electrical power.
• FIG. 6C is a cross-section ofsteam trap514 illustrating a portion ofheat pipe550,heat collector cavity564. As shown inFIG. 6C,heat collector cavity564 lines the interior ofsteam trap514 collecting heat from steam/condensate F.FIG. 6D is a cross-section ofsteam trap514 showing the cylindrical shape ofheat collector cavity564. This shape surrounds steam/condensate F flowing throughsteam trap514 and provides a large surface area for heat transfer from steam/condensate F intoheat pipe550.
• FIG. 6E is another cross-section ofsteam trap514.FIG. 6E illustratessteam trap514 rotated 90 degrees fromFIG. 6C. In addition to the identically numbered elements inFIG. 6C,FIG. 6E showsthermoelectric generator assembly526 further comprisesthermoelectric element552, andheat spreader554.Thermoelectric element552 andheat spreader554 are as described in reference toFIG. 4A, with reference numbers differing by 200.Heat pipe550 comprises fillports560aand560b, plugs562aand562b,heat collector cavity564,heat transport pipe566, andheat dissipater cavity568.Heat collector cavity564 is that portion ofheat pipe550 imbedded within the portion ofsteam trap514 that is in direct contact with steam/condensate F.Heat dissipater cavity568 is that portion ofheat pipe550 that is in direct contact withheat spreader554 ofthermoelectric generator assembly526.Heat transport pipe566 is that portion ofheat pipe550 connectingheat collector cavity564 to heatdissipater cavity568.Heat pipe550 further comprises a wicking device (not shown) and a working fluid present in both liquid and vapor phases (not shown); both wicking device and working fluid are as described above in reference toFIGS. 2D-2F.
• Heat pipe550 extends fromheat collector cavity564 to heatdissipater cavity568 withheat transport pipe566 connectingheat collector cavity564 to heatdissipater cavity568. Employing two fill ports on opposite sides ofheat pipe550 provides for more efficient loading of the working fluid.Heat dissipater cavity568 ofheat pipe550 connects tothermoelectric generator assembly526 atheat spreader554.Heat spreader554 is intimately attached to one side ofthermoelectric element552 andheat transfer device527 is intimately attached to the other side ofthermoelectric element552,opposite heat spreader554.Insulation528 is positioned in a gap betweenheat transfer device527 and the external surface ofsteam trap514, extending beyond the edges ofheat transfer device527 to insure good thermal isolation betweenheat transfer device527 and the exterior surfaces ofsteam trap514.
• Power for data transmission is supplied by the operation ofthermoelectric generator assembly526 with a heat flow efficiently supplied byheat pipe550 as described above in reference toFIG. 4A with reference numbers increased by 200. Although the embodiment ofFIGS. 6A-6E is described with a single thermoelectric generator assembly, it is understood that a second thermoelectric generator assembly, identical to the first, may be added to increase the power available to the wireless data router for application requiring, for example, more frequent communications with the wireless field device mesh network.
• The embodiment of the present invention shown inFIGS. 6A-6E greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within a steam trap in direct contact with a flow of steam and condensate. By penetrating the steam trap wall directly, the problem of thermal resistance through the steam trap wall is eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the external surfaces of the steam trap. Also, because the heat flows intoheat pipe550 from the entire surface area ofheat collector cavity564 and is transported by the heat of vaporization from the entire internal heat collector cavity surface, the heat flux transported byheat pipe550 can be extremely high.
• FIGS. 7A-7E illustrate yet another embodiment of the present invention for powering a wireless device in a wireless field device mesh network with a thermoelectric generator incorporated into a process component, where the process component is a Venturi tube and the wireless device is a wireless flow measurement field device. As with the orifice plate flange and steam trap embodiments described above, this embodiment replaces a section of process piping through which a process fluid (or process fluid by-product) flows, instead of attaching to an external opening in a process vessel. A Venturi tube includes convergent and divergent cone sections leading to and from a cylindrical section, respectively. The cylindrical section restricts fluid flow, resulting in a lower pressure in the cylindrical section as compared to a pressure at an inlet section. Venturi tubes such as those found in, for example, the Daniel® Venturi Tube, include two pressure taps, one at the inlet section and one at the cylindrical section for transmitting fluid pressure in the Venturi tube to a DP sensor via impulse lines. The pressure differential relates to the flow rate through the Venturi tube, through the application of Bernoulli's equation. An increase in flow rate produces a larger difference between the two pressures. The two pressures transmit through the pressure taps and impulse lines to the DP sensor which directly measures the difference between the two pressures.
• The embodiment shown inFIGS. 7A and 7B illustrates a process component incorporating the present invention where the process component is Venturi tube.FIG. 7A shows process measurement orcontrol point610, including wireless flowmeasurement field device612,Venturi tube614, and process piping620 containing process fluid F. A heat sink is provided by ambient fluid A. Wireless flowmeasurement field device612 compriseselectronics housing622,electronics circuitry623,antenna624, differential pressure (DP)sensor630, high-side (upstream)impulse line632, and low-side (downstream)impulse line634 as described above with reference toFIG. 5A with reference numbers increased by 200.FIG. 7B showsVenturi tube614 ofFIG. 7A rotated 90 degrees about the flow axis.Venturi tube614 is an in-line process component comprising high-side pressure tap633, low-side pressure tap635, thermoelectric generator assembly626 (shown inFIGS. 7C and 7E),heat transfer device627,insulation628, and heat pipe650 (shown inFIGS. 7C-7E).Thermoelectric generator assembly626 comprisespower cable658. As illustrated,heat transfer device627 is a pin-fin heat exchanger.
• ConsideringFIGS. 7A and 7B together,Venturi tube614 is attached to process piping620 at flanges W by, for example, welding or bolting.Thermoelectric generator assembly626 is integrated withVenturi tube614 and is in thermal contact with process fluid F and ambientfluid A. Insulation628 is positioned to thermally shieldheat transfer device627 in thermal contact with fluid A from portions ofVenturi tube614 in thermal contact with process fluidF. Impulse line632 connects toVenturi tube614 atpressure tap633 by, for example, a threaded connection. Similarly,impulse line634 connects to pressuretap635.Impulse line632 andimpulse line634connect pressure tap633 andpressure tap635, respectively, toDP sensor630, physically connecting wireless flowmeasurement field device612 toVenturi tube614. Connections withinelectronics housing622 are as described in reference toFIG. 5A above, with reference numbers increased by 200.
• FIG. 7C is a longitudinal section ofVenturi tube614 illustratingthermoelectric generator assembly626,insulation628, andheat pipe650.Thermoelectric generator assembly626 further comprisesthermoelectric element652, and heat spreader654.Thermoelectric element652 and heat spreader654 are as described in reference toFIG. 4A, with reference numbers differing by 300.Heat pipe650 comprises fill port660, plug662,heat collector cavity664,heat transport pipe666, andheat dissipater cavity668.Heat collector cavity664 is that portion ofheat pipe650 imbedded within the portion ofVenturi tube614 that is in direct contact with process fluid F.Heat dissipater cavity668 is that portion ofheat pipe650 that is in direct contact withthermoelectric generator assembly626.Heat transport pipe666 is that portion ofheat pipe650 connectingheat collector cavity664 to heatdissipater cavity668.Heat pipe650 further comprises a wicking device (not shown) and a working fluid present in both liquid and vapor phases (not shown); both wicking device and working fluid are as described above in reference toFIGS. 2D-2F.
• At least some power for the flow measurement and data transmission is supplied by the operation ofthermoelectric generator assembly626 with a heat flow efficiently supplied byheat pipe650.Heat collector cavity664 collects heat from process fluid F.Heat transport pipe666 transfers the heat fromheat collector cavity664 to heatdissipater cavity668. Atheat dissipater cavity668, heat is transferred into heat spreader654, which evens out the heat flux as the heat flow conducts through heat spreader654 tothermoelectric element652. As the heat flows through thermoelectric element652 a voltage and a current are generated as a function of the amount of heat flowing throughthermoelectric element652. Power produced bythermoelectric element652 is conducted bypower cable658 toelectronics circuitry623 within electronics housing622 atpower control circuitry644.
• As illustrated inFIG. 7C,heat collector cavity664 extends along much of a portion of the cylindrical section ofVenturi tube614 that directly contacts process fluid F.FIG. 7D is a cross-section ofVenturi tube614 showing the cylindrical shape ofheat collector cavity664. This shape surrounds the flow of process fluid F and provides a large surface area for heat transfer from process fluid F intoheat pipe650.
• FIG. 7E is another cross-section ofVenturi tube614. In addition to the identically numbered elements inFIG. 7C,FIG. 7E shows lowside pressure tap635.Heat transfer device627 extends significantly beyondthermoelectric element652 to provide a large ratio of surface area to volume to enhance the transfer of heat with ambientfluid A. Insulation628 is positioned in the gap betweenheat transfer device627 and the external surface ofVenturi tube614, extending well beyond the edges ofheat transfer device627 to insure good thermal isolation betweenheat transfer device627 and the external surface ofVenturi tube614. As shown inFIG. 7E,heat pipe650 is completely separate from, and does not interfere with the functioning of lowside pressure tap635.
• The embodiment of the present invention shown inFIGS. 7A-7E greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within a Venturi tube in direct contact with a process fluid. By penetrating the vessel wall directly, the problem of thermal resistance through the vessel wall is eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the vessel wall. Also, because the heat flows intoheat pipe650 from the entire surface area ofheat collector cavity664 and is transported by the heat of vaporization from the entire internal heat collector cavity surface, the heat flux transported byheat pipe650 is extremely high. Although the embodiment illustrated inFIGS. 7A-7E is a Venturi tube, it is understood to apply as well to other flow tube systems, for example, a magnetic flow meter tube and a vortex tube.
• FIGS. 8A-8F illustrate yet another embodiment of the present invention for powering a wireless device in a wireless field device mesh network with a thermoelectric generator incorporated into a process component, where the process component is a centrifugal pump and the wireless device is a wireless data router. As with several of the previous embodiments described above, this embodiment replaces a section of process piping through which a process fluid (or process fluid by-product) flows, instead of attaching to an external surface of a process vessel (clamp on). A pump is attached in series with process piping carrying a process fluid to increase the velocity of the fluid or to increase the pressure of the process fluid by adding kinetic energy to the process fluid. Kinetic energy is supplied in, for example, a centrifugal pump, by a rotating impeller which employs centripetal force to accelerate the process fluid in a radial direction.
• The embodiment shown inFIGS. 8A-8C illustrates a process component incorporating the present invention where the process component is a pump.FIG. 8A shows process measurement orcontrol point710, includingwireless data router712, pump714, and process piping720 containing process fluid F. A heat sink is provided by ambient fluid A.Wireless data router712 compriseselectronics housing722,electronics circuitry723, andantenna724 and is as described above in reference toFIG. 6B with reference numbers increased by 200.Pump714 is an in-line process component comprisingthermoelectric generator assembly726,heat transfer device727, andinsulation728. As illustrated,heat transfer device727 is a pin-fin heat exchanger.
• FIG. 8B is a cross-section ofpump714 showing that pump714 further comprisesheat pipe750,impeller780,motor782,shaft784, and bearing/seal786. The internal components ofmotor782 are omitted for clarity.FIG. 8B showspump714 rotated 90 degrees about axis ofshaft784.FIG. 8C is a portion ofFIG. 8B enlarged to better illustrate the details ofthermoelectric generator assembly726,insulation728, and a portion ofheat pipe750.FIG. 8C shows an extended portion ofpump714 attached to the main portion ofpump714 by, for example, a threaded connection (as shown) or a welded connection.Thermoelectric generator assembly726 comprisesthermoelectric element752,heat spreader754, andpower cable758 and is as described above in reference toFIG. 4A with references numbers increased by 400.Heat pipe750 comprisesfill port760, plug762,heat collector cavity764,heat transport pipe766, andheat dissipater cavity768.Heat collector cavity764 is that portion ofheat pipe750 imbedded within the portion ofpump714 that is in direct contact with process fluid F.Heat dissipater cavity768 is that portion ofheat pipe750 that is in direct contact withthermoelectric generator assembly726.Heat transport pipe766 is that portion ofheat pipe750 connectingheat collector cavity764 to heatdissipater cavity768.Heat pipe750 further comprises awicking device772 and a working fluid present in both liquid and vapor phases (not shown); both wickingdevice772 and working fluid are as described above in reference toFIGS. 2D-2F.Impeller780 is a generally frustoconical shaped device with blades that accelerate process fluid F whenimpeller780 spins to produce increased velocity of, or higher pressure in, process fluid F as it exitspump714.Motor782 is any sort of motor, such as an electric motor.Shaft784 is a durable, generally cylindrically shaped device for connectingmotor782 toimpeller780 to spinimpeller780. Bearing/seal786 is a device that permits the passage and rotation ofshaft784 while largely preventing leakage of process fluid F pastshaft784.
• ConsideringFIGS. 8A,8B, and8C together, pump714 is attached to process piping720 at flanges W by, for example, welding or bolting.Thermoelectric generator assembly726 is integrated withpump714 and is in thermal contact with process fluid F and ambient fluid A. Connections withinelectronics housing722 are as described in reference toFIG. 6B above, with reference numbers increased by 200.Heat pipe750 extends fromheat collector cavity764 to heatdissipater cavity768 withheat transport pipe766 connectingheat collector cavity764 to heatdissipater cavity768.Heat dissipater cavity768 ofheat pipe750 connects tothermoelectric generator assembly726 atheat spreader754.Heat spreader754 is intimately attached to one side ofthermoelectric element752 andheat transfer device727 is intimately attached to the other side ofthermoelectric element752,opposite heat spreader754.
• In operation,motor782 spinsimpeller780 viashaft784, drawing process fluid F intopump714, and accelerating process fluid F to produce increased velocity of, or higher pressure in, process fluid F as it exitspump714.Wireless data router712 operates as described in reference toFIG. 6B above with reference numbers increased by 200.
• At least a portion of the power for the operation ofwireless data router712 is supplied in the embodiment of the present invention by the operation ofthermoelectric generator assembly726 with a heat flow efficiently supplied byheat pipe750 as described above in reference toFIG. 4A with reference numbers increased by 400.
• As illustrated inFIG. 8B,heat collector cavity764 lines the interior ofpump714 collecting heat from process fluid F as it is pumped throughpump714 byimpeller780.FIGS. 8D-8F are axial cross-sections ofpump714 further illustrating the shape ofheat collector cavity764. Taken together, FIGS.8B and8D-8F show that heatcollector cavity764 surrounds the interior ofpump714, except for openings necessary for the inlet (FIGS. 8B and 8F), outlet (FIG. 8E), and seal/bearing786 (FIGS. 8B and 8D). By surrounding the interior ofpump714, a large surface area is provided for heat transfer from process fluid F intoheat pipe750.
• The embodiment of the present invention shown inFIGS. 8A-8F greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within a pump in direct contact with a process fluid. By penetrating the pump wall directly, the problem of thermal resistance through the pump wall is eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the external surfaces of the pump. Also, because the heat flows intoheat pipe750 from the entire surface area ofheat collector cavity764 and is transported by the heat of vaporization from the entire internal heat collector cavity surface, the heat flux transported byheat pipe750 is extremely high. Although the embodiment ofFIGS. 8A-8F is described as a centrifugal pump, it is understood to apply to any type of pump.
• FIGS. 9A-9C illustrate yet another embodiment of the present invention for powering a wireless device in a wireless field device mesh network with a thermoelectric generator incorporated into a process component, where the process component is an orifice plate and the wireless device is a wireless flow measurement field device. Like some of the embodiments described above, this embodiment replaces a section of process piping through which a process fluid (or process fluid by-product) flows, instead of attaching to an external opening in a process vessel. Orifice plates such as for example, a Rosemount® 1495 Orifice Plate, positioned between two orifice plate flanges cause a pressure drop across the orifice plate as the fluid is forced to flow through the orifice, resulting in two different fluid pressures being transmitted to the DP sensor, as described above in reference toFIGS. 5A-5F.
• FIGS. 9A-9C illustrate a process component incorporating the present invention where the process component is an orifice plate.FIG. 9A shows process measurement orcontrol point810, including wireless flowmeasurement field device812,orifice plate flange814,orifice plate815,orifice plate flange816, stud/nuts818 and process piping820 containing process fluid F. A heat sink is provided by ambient fluid A. Wireless flowmeasurement field device812 compriseselectronics housing822,electronics circuitry823,antenna824,RF cable825, differential pressure (DP)sensor830, high-side (upstream)impulse line832, and low-side (downstream)impulse line834.DP sensor830,impulse lines832 and834, andelectronics circuitry823 are as described above in reference toFIG. 5A, with reference numbers increased by 400.Orifice plate flange814 and816, such as those found in, for example, a Rosemount® 1496 Flange Union, include high-side pressure tap833 and low-side pressure tap835, respectively.Orifice plate815 is an in-line process component comprising thermoelectric generator assembly826 (shown inFIGS. 9B-9C),heat transfer device827,insulation828, and heat pipe850 (shown inFIGS. 9B-9C). Together,orifice plate flange814,orifice plate815,orifice plate flange816, studs/nuts818, and two sealing gaskets821 (shown inFIG. 9B) comprise an orifice plate flange union.Thermoelectric generator assembly826 comprisespower cable858. As illustrated,heat transfer device827 is a pin-fin heat exchanger.
• Orifice plate flanges814 and816 attach to process piping820 at points W by, for example, welding.Orifice plate815 is inserted betweenorifice plate flange814 andorifice plate flange816 with a sealinggasket821 betweenorifice plate815 andorifice plate flange814 and another sealinggasket821 betweenorifice plate815 andorifice plate flange816.Orifice plate flange814,orifice plate815,orifice plate flange816, and the two gaskets are bolted together by a plurality of stud/nuts818.Thermoelectric generator assembly826 is integrated withorifice plate815 and is in thermal contact with process fluid F and ambientfluid A. Insulation828 is positioned to thermally shieldheat transfer device827 in thermal contact with fluid A from portions oforifice plate815 in thermal contact with processfluid F. Antenna824 is located remotely fromelectronics housing822 and is connected toelectronics circuitry823 byRF cable825. All other connections are as described above in reference toFIG. 5A, with reference numbers increased by 400. Operation is also as described above in reference toFIG. 5A.
• At least a portion of power for the flow measurement and data transmission described above is supplied to wireless flowmeasurement field device812 in the embodiment of the present invention by the operation ofthermoelectric generator assembly826 with a heat flow efficiently supplied byheat pipe850 as described in detail inFIGS. 9B-9C. A heat flow driven by the temperature difference between process fluid F and ambient fluid A is transported byheat pipe850 inorifice plate815. The heat flow is conducted throughthermoelectric generator assembly826 by the dissipation of the heat into ambient fluid A byheat transfer device827, generating electrical power.
• FIGS. 9B and 9C are longitudinal and axial cross-sections, respectively, oforifice plate815 illustratingthermoelectric generator assembly826,insulation828, andheat pipe850. ConsideringFIGS. 9B and 9C together,thermoelectric generator assembly826 comprisesthermoelectric element852,heat spreader854, andpower cable858.Thermoelectric element852 andheat spreader854 are as described in reference toFIG. 4A, with reference numbers increased by 500.Heat pipe850 comprisesfill port860, plug862,heat collector cavity864,heat transport pipe866, andheat dissipater cavity868.Heat collector cavity864 is that portion ofheat pipe850 imbedded within the portion oforifice plate815 that is in direct contact with process fluid F.Heat dissipater cavity868 is that portion ofheat pipe850 that is in direct contact withthermoelectric generator assembly826.Heat transport pipe866 is that portion ofheat pipe850 connectingheat collector cavity864 to heatdissipater cavity868.Heat pipe850 further comprises a wicking device (not shown) and a working fluid present in both liquid and vapor phases (not shown); both wicking device and working fluid are as described above in reference toFIGS. 2D-2F.
• Heat pipe850 extends fromheat collector cavity864 to heatdissipater cavity868 withheat transport pipe866 connectingheat collector cavity864 to heatdissipater cavity868.Heat dissipater cavity868 ofheat pipe850 connects tothermoelectric generator assembly826 atheat spreader854.Heat spreader854 is intimately attached to one side ofthermoelectric element852 andheat transfer device827 is intimately attached to the other side ofthermoelectric element852,opposite heat spreader854.Power cable858 connectsthermoelectric element852 toelectronics circuitry823 within electronics housing822 at power control circuitry844 (shown inFIG. 9A).
• Power for the flow measurement and data transmission is supplied by the operation ofthermoelectric generator assembly826 with a heat flow efficiently supplied byheat pipe850 as described above in reference toFIG. 4A with reference numbers increased by 500. As illustrated inFIGS. 9B and 9C,heat collector cavity864 extends along much of a portion oforifice plate815 that is proximate process fluid F.
• The embodiment of the present invention shown inFIGS. 9A-9C greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within an orifice plate in direct contact with a process fluid. By penetrating the vessel wall directly, the problem of thermal resistance through the vessel wall is eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the vessel wall. Also, because the heat flows intoheat pipe850 from the entire surface area ofheat collector cavity864 and is transported by the heat of vaporization from the entire internal heat collector cavity surface, the heat flux is efficiently transported byheat pipe850. Finally, orifice plates are designed to be quickly and easily changed. Thus, an orifice plate embodying the present invention, such as that shown inFIGS. 9A-9C, can easily replace an orifice plate not embodying the invention to supply power to a wireless device.
• All embodiments described above are shown with a heat transfer device illustrated as a pin-fin heat exchanger. However, it is understood that a heat transfer device is any device for efficiently exchanging heat with ambient fluid A. Another example of a heat transfer device is a finned heat exchanger. Still another example of a heat transfer device is a device employing a second heat pipe in thermal contact with the side of the thermoelectric element opposite the heat spreader to further enhance the transfer of heat into the ambient fluid.
• FIG. 10 illustrates an embodiment of the present invention incorporated into each of two process components for powering a wireless flow measurement field device. This embodiment differs from all embodiments described above in that, for each of the two process components, the heat sink is the process fluid in the other process component. Also, for each of the two process components, the heat transfer device is the other process component's heat pipe.FIG. 10 is a cross-section oforifice plate flanges914aand914b.Orifice plate flanges914aand914bare each identical in form and function to orificeplate flange414 as described in reference toFIGS. 5A-5F except for the following differences. The extended portion of eachorifice plate flange914aand914bincludesflange connection988aand988b, respectively. In addition,insulation928aand928bextend up the extended portion oforifice plate flange914aand914bonly to flangeconnections988aand988b, respectively.Orifice plate flanges914aand914bsharethermoelectric generator assembly926, which includesthermoelectric element952,first heat spreader954a,second heat spreader954b, andpower cable958. Finally, the heat transfer device fororifice plate flange914aisheat pipe950boforifice plate flange914b; similarly, the heat transfer device fororifice plate flange914bisheat pipe950aoforifice plate flange914a. The embodiment shown inFIG. 10 also comprisesinterface gasket990, clampgaskets992, and clamps994.Interface gasket990 and clampgaskets992 are a compressible gasket material that is also a thermal insulator.
• Orifice plate flanges914aand914bare connected atthermoelectric generator assembly926, withheat pipe950aconnecting tothermoelectric generator assembly926 atheat spreader954a, andheat pipe950bconnecting tothermoelectric generator assembly926 atheat spreader954b.Heat spreader954ais in intimate contact with one side ofthermoelectric element952 andheat spreader954bofthermoelectric generator assembly926 in intimate contact with the other side ofthermoelectric element952,opposite heat spreader954a.Power cable958 connectsthermoelectric element952 to a wireless device of any type as shown in the previous embodiments. The connection betweenorifice plate flanges914aand914bsupported byflange connections988aand988bheld together byclamp994.Clamp gaskets992, betweenclamp994 andflange connections988aand988blimit the flow of heat aroundthermoelectric element952 viaclamp994. Similarly,interface gasket990, betweenflange connections988aand988b, limits the flow of heat aroundthermoelectric element952 viaflange connections988aand988b.
• As shown inFIG. 10,heat transfer pipes966aand966bofheat pipe950aand950b, respectively, are formed of a flexible tube instead of a rigid structure. This allows for easier connection offlange connection988atoflange connection988bthan if the heat transfer portions of each ofheat pipe950aand950bwere a rigid structure. The flexible tube is preferably a thin-walled metal tube, such as, for example, an armored sleeve for a capillary-style seal connection for a Rosemount® 1199 Diaphragm Seal System.
• In operation, a heat flow is driven by the temperature difference between process fluid F1 in contact withorifice plate flange914aand process fluid F2 in contact withorifice plate flange914b, with, for example, the temperature of process fluid F1 greater than the temperature of process fluid F2. The heat flow is transported from process fluid F1 byheat pipe950ainorifice plate flange914ato heatspreader954a. The heat flow is conducted throughthermoelectric generator952 to heatspreader954bby the transport of the heat flow fromheat spreader954bbyheat pipe950bto process fluid F2 inorifice plate flange914b. The conduction of the heat flow throughthermoelectric generator952 generates electrical power, which is conducted overpower cable958 to a wireless device of any type as shown in the previous embodiments.
• The embodiment of the present invention shown inFIG. 10 greatly improves the heat flux available for conversion by the thermoelectric generator by imbedding a heat pipe within each of two orifice plate flanges, each orifice plate flange in direct contact with a process fluid at a temperature different than that of the other orifice plate flange. By penetrating the vessel walls directly, the problem of thermal resistance through the vessel walls is eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the vessel walls. In addition, the embodiment ofFIG. 10 may produce larger and/or more controllable heat flows by control of the temperatures of the process fluid in contact with each of the two orifice plate flanges.
• All embodiments above are described with a heat pipe that preferably employs a wicking device to permit operation of the heat pipe in all orientations. The wicking device permits movement of the denser liquid phase working fluid from the heat dissipater cavity to the heat collector cavity regardless of the orientation of the heat pipe, including against the force of gravity. It is understood that for all embodiments, the wicking device may be omitted if the orientation of the device places the heat dissipater cavity above the heat collector cavity such that the vapor phase working fluid rises to the heat dissipater cavity and the liquid phase working fluid flows downward to the heat collector cavity, the vapor phase working fluid being much less dense than the liquid phase working fluid.
• In some embodiments above, the antenna is shown mounted to the exterior of the electronics housing and electrically connected to the transceiver. In other embodiments it is shown mounted remotely and connected to the electronics housing by an RF cable or mounted completely within the electronics housing, for example, a component mounted on a circuit board or a component integrated with a circuit board. It is understood that any of the embodiments may employ any of these integrated antenna styles as desired.
• As shown above in reference toFIG. 10, a heat transfer pipe of a heat pipe in the present invention may be formed of a flexible tube instead of a rigid structure. Although illustrated only for the embodiment shown inFIG. 10, it is understood that in all of the embodiments, the heat transfer pipe of the heat pipe may be formed at least in part, by a flexible tube instead of a rigid structure. This may allow for easier connection of a thermoelectric assembly to a heat transfer device for a particular heat sink, such as large structure, for example, earth or an earthen berm. In addition, in the case of a heat transfer device that is, for example, a pin-fin heat exchanger and the heat sink is, for example, ambient air, a flexible tube structure permits easy adjustment and orientation of the pin-fin heat exchanger for improved natural convection, resulting in improved performance of the heat transfer device. Finally, employing a flexible tube structure for at least a portion of the heat transfer pipe of the heat pipe provides vibration isolation between portions of the process component in contact with the process fluid and the thermoelectric generator assembly. In high-vibration process environments, this enhances the reliability of the thermoelectric generator assembly.
• The various embodiments provide power to a wireless device in a wireless field device network by employing a thermoelectric generator incorporated into a process component. The process component directly contacts a process fluid and contains a heat pipe formed in part by a heat collector cavity internal to the process component. The heat collector cavity is employed solely to form a portion of the heat pipe. The heat pipe couples to one side of the thermoelectric generator and a heat sink couples to the other side of the thermoelectric generator, transferring heat through the thermoelectric generator to generate electrical power for the wireless device. Imbedding the heat pipe within a process component in direct contact with the process fluid eliminates thermal resistances by penetrating a vessel wall directly. By penetrating the vessel wall directly, losses associated with thermal resistance through the vessel wall are eliminated as is the need to achieve a good thermal connection between the thermoelectric generator and the exterior wall of the vessel. In addition, because heat flows into the heat pipe from the entire surface area of the heat collector cavity and is transported by the heat of vaporization from the entire internal heat collector cavity surface, the heat flux transported by the heat pipe is extremely high. Finally, because a process component incorporating the present invention can be assembled at a factory under precisely controlled conditions, consistent, reliable operation is much more likely than with a thermoelectric generator strapped on to a vessel out in the field.
• While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (46)

1. An apparatus comprising:

a first process component for directly contacting a first process fluid, the first process component having a first cavity proximate the first process fluid;

a first heat pipe formed in part by the first cavity, the first heat pipe comprising a first working fluid; and

a thermoelectric generator assembly; wherein the first heat pipe is thermally coupled to a first side of the thermoelectric generator assembly and a heat sink is thermally coupled to a second side of the thermoelectric generator assembly; wherein the thermoelectric generator assembly produces electrical power:

2. The apparatus ofclaim 1, further comprising a wireless transceiver, wherein the electrical power produced by the thermoelectric generator assembly at least partially powers the wireless transceiver.

3. The apparatus ofclaim 2, further comprising a data router, wherein the electrical power produced by the thermoelectric generator assembly at least partially powers the data router.

4. The apparatus ofclaim 1, further comprising a transducer, wherein the electrical power produced by the thermoelectric generator assembly at least partially powers the transducer.

5. The apparatus ofclaim 1, further comprising an energy storage device for storing the electrical power.

6. The apparatus ofclaim 1, wherein the first process component is one of a pipe flange, an orifice plate flange, an orifice plate, a thermowell, an averaging pitot tube, a stream trap, a flow tube, a flow straightening element, a control valve, a shut-off valve, a pressure relief valve, a pressure manifold, a valve manifold, a pump housing, a filter housing, a pressure sensor remote seal, a level switch, a contacting radar level gauge, a vortex flow meter, a coriolis meter, a magnetic flow meter, a turbine meter, and a flow restrictor.

7. The apparatus ofclaim 1, wherein the heat sink is at least one of ambient air, water, a second process fluid, earth, a building, and an earthen berm.

8. The apparatus ofclaim 1, wherein the first working fluid comprises at least one of water, ammonia, methanol, and ethanol.

9. The apparatus ofclaim 1, wherein the first heat pipe is further formed in part by a flexible tube.

10. The apparatus ofclaim 1, wherein the first heat pipe further comprises a wicking device.

11. The apparatus ofclaim 10, wherein the wicking device is comprised of at least one of a sintered ceramic, metal mesh, metal felt, and metal foam.

12. The apparatus ofclaim 10, wherein the wicking device is comprised of grooves on the interior surface of the heat pipe.

13. The apparatus ofclaim 1, further comprising:

a heat transfer device; and

the thermoelectric generator assembly comprises:

a first heat spreader; and

a thermoelectric element,

wherein the first heat spreader is attached to a first side of the thermoelectric element to thermally couple the first side of the thermoelectric generator assembly to the first heat pipe; and

wherein the heat transfer device thermally couples the heat sink to the second side of the thermoelectric generator assembly.

14. The apparatus ofclaim 13, further comprising thermal insulation between at least a portion of the first process component and the heat transfer device.

15. The apparatus ofclaim 13, wherein the heat transfer device comprises at least one of a pin-fin heat exchanger and a finned heat exchanger.

16. The apparatus ofclaim 13, wherein:

the thermoelectric generator assembly further comprises a second heat spreader;

the heat transfer device comprises a second heat pipe; and

the second heat spreader is attached to a second side of the thermoelectric element to thermally couple the second side of the thermoelectric generator assembly to the second heat pipe.

17. The apparatus ofclaim 16, wherein the heat sink is a second process fluid and the heat transfer device further comprises:

a second process component for directly contacting the second process fluid, the second process component having a second cavity proximate the second process fluid;

wherein the second heat pipe is formed in part by the second cavity, the second heat pipe comprising a second working fluid.

18. The apparatus ofclaim 17, wherein at least one of the first working fluid and the second working fluid comprises at least one of water, ammonia, methanol, and ethanol.

19. The apparatus ofclaim 17, wherein at least one of the first heat pipe and the second heat pipe is further formed in part by a flexible tube.

20. The apparatus ofclaim 17, wherein at least one of the first heat pipe and the second heat pipe further comprises a wicking device.

21. The apparatus ofclaim 20, wherein the wicking device is comprised of at least one of a sintered ceramic, metal mesh, metal felt, and metal foam.

22. The apparatus ofclaim 20, wherein the wicking device is comprised of grooves on the interior surface of the heat pipe.

23. A system comprising:

a wireless field device network;

a wireless device in wireless communication with the wireless field device network; and

a first process component for directly contacting a first process fluid, the first process component having a first cavity proximate the first process fluid;

a first heat pipe formed in part by the first cavity, the first heat pipe comprising a first working fluid; and

a thermoelectric generator assembly, wherein the first heat pipe is thermally coupled to a first side of the thermoelectric generator assembly and a heat sink is thermally coupled to a second side of the thermoelectric generator assembly;

wherein the thermoelectric generator assembly provides electrical power to the wireless device.

24. The system ofclaim 23, wherein the wireless device is one of a wireless transceiver, a wireless data router, and a wireless field device.

25. The system ofclaim 23, wherein the wireless field device network comprises a gateway, and wherein the thermoelectric generator assembly provides electrical power to the gateway.

26. The system ofclaim 23, wherein the wireless field device network comprises at least one of a remote telemetry unit and a backhaul radio and wherein the thermoelectric generator assembly provides electrical power to at least one of the remote telemetry unit and the backhaul radio.

27. The system ofclaim 23, wherein the process component is one of a pipe flange, an orifice plate flange, an orifice plate, a thermowell, an averaging pitot tube, a stream trap, a flow tube, a flow straightening element, a control valve, a shut-off valve, a pressure relief valve, a pressure manifold, a valve manifold, a pump housing, a filter housing, a pressure sensor remote seal, a level switch, a contacting radar level gauge, a vortex flow meter, a coriolis meter, a magnetic flow meter, a turbine meter, and a flow restrictor.

28. The system ofclaim 23, wherein the heat sink is at least one of ambient air, water, a second process fluid, earth, a building, and an earthen berm.

29. The system ofclaim 23, wherein the first working fluid is at least one of water, ammonia, methanol, and ethanol.

30. The system ofclaim 23, wherein the first heat pipe further comprises a wicking device.

31. The system ofclaim 30, wherein the wicking device is comprised of at least one of a sintered ceramic, metal mesh, metal felt, and metal foam.

32. The system ofclaim 30, wherein the wicking device is comprised of grooves on the interior surface of the heat pipe.

33. The system ofclaim 23, further comprising:

a heat transfer device; and

the thermoelectric generator assembly comprises:

a first heat spreader, and

a thermoelectric element,

wherein the first heat spreader is attached to a first side of the thermoelectric element to thermally couple the first side of the thermoelectric generator assembly to the first heat pipe; and

wherein the heat transfer device thermally couples the heat sink to the second side of the thermoelectric generator assembly.

34. The apparatus ofclaim 33, further comprising thermal insulation between at least a portion of the first process component and the heat sink.

35. The system ofclaim 33, wherein the heat transfer device comprises at least one of a pin-fin heat exchanger and a finned heat exchanger.

36. The system ofclaim 33, wherein:

the thermoelectric generator assembly further comprises a second heat spreader;

the heat transfer device comprises a second heat pipe; and

the second heat spreader is attached to a second side of the thermoelectric element to thermally couple the second side of the thermoelectric generator assembly to the second heat pipe.

37. The system ofclaim 36, wherein the heat sink is a second process fluid and the heat transfer device further comprises:

a second process component for directly contacting the second process fluid, the second process component having a second cavity proximate the second process fluid;

wherein the second heat pipe is formed in part by the second cavity, the second heat pipe comprising a second working fluid.

38. The system ofclaim 37, wherein at least one of the first working fluid and the second working fluid comprises at least one of water, ammonia, methanol and ethanol.

39. The system ofclaim 37, wherein the at least one of the first heat pipe and the second heat pipe is further formed in part by a flexible tube.

40. The system ofclaim 37, wherein the at least one of the first heat pipe and the second heat pipe further comprises a wicking device.

41. The system ofclaim 40, wherein the wicking device is comprised of at least one of a sintered ceramic, metal mesh, metal felt, and metal foam.

42. The system ofclaim 40, wherein the wicking device is comprised of grooves on the interior surface of the heat pipe.

43. A method for generating electrical power for use in a wireless field device network, the method comprising:

contacting a process component with a process fluid;

conducting heat between the process fluid and a surface of a sealed cavity within the process component;

transferring heat between the surface of the sealed cavity and a thermoelectric generator assembly by vaporizing and condensing a working fluid;

conducting heat through the thermoelectric generator assembly;

transferring heat between the thermoelectric generator assembly and a heat sink by at least one of convection and conduction; and

generating electrical power from the conduction of heat through the thermoelectric generator assembly.

44. The method ofclaim 43, wherein the transferring heat between the surface of the sealed cavity and a thermoelectric generator assembly further comprises wicking the condensed working fluid toward the vaporizing working fluid.

45. The method ofclaim 43, further comprising insulating the thermoelectric generator assembly from heat transfer with the process fluid other than by condensing and vaporizing the working fluid.

46. The method ofclaim 43, further comprising powering at least partially a wireless device with the generated electrical power.

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