US20090173336A1 - Active thermal energy storage system and tank for use therein - Google Patents

Abstract

An active thermal energy storage system is disclosed which uses an energy storage material that is stable at atmospheric pressure and temperature and has a melting point higher than 32 degrees F. This energy storage material is held within a storage tank and used as an energy storage source, from which a heat transfer system (e.g., a heat pump) can draw to provide heating of residential or commercial buildings and associated hot water. The energy storage material may also accept waste heat from a conventional air conditioning loop, and may store such heat until needed. The system may be supplemented by a solar panel system that can be used to collect energy during daylight hours, storing the collected energy in the energy storage material. The stored energy may then be used during the evening hours to heat recirculation air for a building in which the system is installed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation-in-part of co-pending U.S. non-provisional patent application Ser. No. 12/212,822, filed Sep. 18, 2008, which is a continuation of U.S. non-provisional patent application Ser. No. 11/818,401, filed Jun. 13, 2007, now U.S. Pat. No. 7,441,558, which is a non-provisional of U.S. provisional patent application Ser. No. 60/852,844, filed Oct. 19, 2006, the entirety of which applications are incorporated herein by reference.
FIELD OF THE INVENTION
• The invention relates to a system for heating and cooling of residential and commercial building spaces and hot water systems, and more particularly to an active heat transfer system used for use in efficiently controlling air and water temperature in commercial buildings and residences.
BACKGROUND OF THE INVENTION
• The electrical energy generation and distribution networks in the United States are currently stressed to the limit by peak demands during daytime hours. Quite expectedly, the demands of the industrial sector, commercial and residential air conditioning and water heating are highest during the daytime hours. During the off peak, late evening and night time hours, the opposite is true, and there normally is excess electrical power available which is not needed in the local power grid.
• Using nationwide transmission power lines, the power generation and distribution grid is used to transfer excess power to other grids that require it. This is a form of load leveling that is aimed at maintaining the coal, oil or nuclear power generation plants at a level, constant, load. The problem with such a load leveling scheme is that costs are high, due to the costs of transmission and line losses inherent in cross-country transmission to other power grids.
• Further, large coal, oil and nuclear power generation plants operate most efficiently when running at full capacity. Due to the short time of peak demand large generation facilities are not scaled to peak demand. Smaller generation units are started up to meet the extra needs of peak demand. This allows the large generation units to run at full capacity for most of the day. These smaller generation units are significantly more costly and polluting than their larger counterparts.
• It would be advantageous to provide a system that enables local off-peak utilization of the excess power from the local grid, thus reducing costs associated with peak production, pollution associated with that peak production, and also reducing costs associated with transmission of excess power over long distances.
SUMMARY OF THE INVENTION
• A system is disclosed for storing excess local grid power produced during off peak hours (e.g., night, holidays, etc.), for use in heating/cooling systems in residential and commercial buildings during peak (e.g., daytime) periods. An active thermal energy storage system (hereinafter referred to as “ATESS”) is disclosed for storing this excess local grid off peak power in a thermal energy storage material, such as that described in U.S. Pat. No. 3,976,584 to Leifer, and for using the stored energy to control air and water temperatures in residential dwelling and/or commercial buildings during peak energy periods. It will be appreciated, however, that the ATESS may be used to provide energy for heating/cooling at any time during a 24 hour day, and not just during the peak energy periods.
• The ATESS facilitates the use of off peak excess electrical energy, thus reducing the need for oil and natural gas systems that are typically used for air and hot water heating in residential dwellings or commercial buildings. Thus, the invention relates to the active transfer of thermal heat energy obtained from any of a variety of natural energy sources (e.g., solar, electrical, wind, gas, oil, etc.) to a thermal energy storage material, such as one of the materials described in U.S. Pat. No. 3,976,584 to Leifer, the entire contents of which patent is incorporated herein. The thermal energy storage material may be contained in an appropriate tank or storage vessel (which will be described in greater detail below). The energy stored in the thermal energy storage material may be transferred by an active heat transfer system (e.g., a heat pump) to any of a variety of locations within a residential home or commercial building as needed for air and/or water heating at any time during a 24 hour day.
• The ATESS operates on the principal of collecting limited available input energy from any and all sources (e.g., solar, electricity, wind, oil, gas) and storing that energy in a thermal energy storage material until needed later. The energy stored in the thermal energy storage material may be removed by a heat transfer system (e.g., heat pump) to control the temperature of residential homes or commercial buildings, thus providing the heat energy requirements at any time during a 24 hour day. Hot water or other liquid heating needs can be met by use of a dual integrated or separate heat transfer (e.g., heat pump) system which can transfer the stored energy from the energy storage material as needed for such purpose.
• In one example, systems exist for collecting solar energy from the sun's radiation only during the limited day time hours for use in home air or water heating needs. However, such systems can only provide this energy when the sun is available. During the evening hours or on cloudy days the residential dwelling and/or commercial building air and/or water heating energy needs must be obtained from or supplemented by other available sources of energy, such as oil, natural gas, wind or electrical energy. Thus, alternative sources of energy are required in order to satisfy the full 24 hours of energy needs. The ATESS functions to receive solar energy during daylight hours, and to store that energy in a thermal energy storage material for use at any time during a 24 hour period. Stored energy is then transferred to the area of need by an active heat transfer (e.g., heat pump) system. In this way, the ATESS can make solar energy available 24 hours a day, thus reducing the need for oil or natural gas for residential dwelling and/or commercial building heating and/or water heating energy needs.
• Currently residential dwellings and/or commercial buildings use air-conditioning powered by electricity to remove heat from the air inside the dwellings and\or buildings. Electrical energy is required to remove the heat energy from the inside air to make it comfortable for human occupancy during hot humid days and nights. The ATESS can be configured so that the active heat transfer system (e.g., heat pump) removes heat from the air inside a building, and stores it in the thermal energy storage material. This stored waste heat, which is normally rejected to the outside atmosphere by typical air conditioning units, can then be used to heat the water used in the residential dwellings and/or commercial buildings. It can also be used to provide night time heating needs, as appropriate.
• The ATESS will reduce markedly the daytime peak power electric demands on the electrical power grid and the electric generating equipment of the local power companies. The ATESS enables more efficient local use of energy from the local power grid, thus reducing or eliminating the need for oil and natural gas. Concurrent reductions in the emission of carbon dioxide and other pollutants, normally associated with energy production from oil or natural gas, would also be achieved from residences.
• A thermal energy storage system is disclosed, comprising a first tank for holding a quantity of water, a second tank having a quantity of thermal energy storage material disposed therein, the thermal energy storage material comprising a substantially solid clathrate having a melting point above 32 degrees Fahrenheit (F), and a latent heat of fusion approaching that of water, and recirculation piping connecting the first and second tanks. The recirculation piping may be in fluid communication with an inner volume of said first tank, the recirculation piping further comprising a heating coil disposed within the second tank. Thusly arranged, heated water disposed in said first tank at a first time may be movable within said recirculation piping, and through said heating coil, to transfer heat from the heated water to the thermal energy storage material disposed within the second tank. Furthermore, cool water disposed in said first tank at a second time is movable within said recirculation piping, and through said heating coil, to transfer heat from said thermal energy storage material disposed within the second tank to the cool water.
• A thermal energy storage system is disclosed, comprising a hot water tank for holding a quantity of water, a storage tank having a quantity of thermal energy storage material disposed therein, the thermal energy storage material comprising a substantially solid clathrate having a melting point above 32 degrees Fahrenheit (F), and a piping loop connecting the hot water tank and the storage tank. The piping loop may be in fluid communication with an inner volume of said hot water tank, the piping loop further comprising a heating coil disposed within the storage tank. When a quantity of water in said hot water tank has a temperature greater than a temperature of said thermal energy storage material, said water is movable within said piping loop and heating coil to transfer heat from the water to the thermal energy storage material. When said quantity of water in said hot water tank has a temperature less than a temperature of said thermal energy storage material, said water is movable within said piping loop and heating coil to transfer heat from the thermal energy storage material to the water.
• A thermal energy storage system, comprising a first tank, a second tank, and an air distribution system. The first tank may have a quantity of water disposed therein. The second tank may have a quantity of thermal energy storage material disposed therein. The thermal energy storage material may comprise a phase change material having a melting point above 32 degrees Fahrenheit (F), and a latent heat of fusion approaching that of water. The first and second tanks may be connected by a recirculation loop for moving said water from said first tank through a first coil disposed within said second tank to transfer energy between said water and said thermal energy storage material. Said second tank and said air distribution system may be connected by an air conditioning loop for moving a first heat transfer fluid from a second coil disposed in said second tank to a third coil disposed in said air conditioning system to transfer energy between said thermal energy storage material and air passed over said third coil.
• A thermal energy storage system is disclosed, comprising a first tank, a second tank, and a hot water radiator circulation system. The first tank may have a quantity of water disposed therein. The second tank may have a quantity of thermal energy storage material disposed therein, the thermal energy storage material comprising a phase change material having a melting point above 32 degrees Fahrenheit (F), and a latent heat of fusion approaching that of water. The first and second tanks may be connected by a recirculation loop for moving said water from said first tank through a first coil disposed within said second tank to transfer energy between said water and said thermal energy storage material. The second tank and the hot water radiator circulation system may be connected by loop for moving a first heat transfer fluid from a second coil disposed in said second tank to a water coil disposed in said hot water radiator circulation system to transfer energy between said thermal energy storage material and water passed over said water coil.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 shows the ATESS installed in a dwelling that has an oil or natural gas hot air furnace system;
• FIG. 2 shows the ATESS installed in a dwelling having an oil or natural gas hot air furnace system supplemented with solar water heating collector panels;
• FIG. 3 shows the ATESS installed in a dwelling having an oil or natural gas hot air furnace system and has a separate water heating system (heat pump);
• FIG. 4 shows the ATESS installed in a dwelling having an oil or natural gas hot air furnace system and has a separate water heating system (heat pump), and which further comprises a dual control system for use as an air conditioner;
• FIG. 5 shows the ATESS described inFIG. 3 with photovoltaic solar collection panels for cold winter weather operation; and
• FIG. 6 shows the ATESS described inFIG. 4 with photovoltaic solar collection panels for hot summer weather operation;
• FIG. 7 is a schematic an arrangement of an ATESS test facility used to test system and thermal energy storage material efficacy;
• FIG. 8 is a tabular representation of the results of a 14 day test of the ATESS;
• FIG. 9 is a tabular representation of the performance of the ATESS on an hourly basis throughout a 24-hour day;
• FIGS. 10A-C are tabular representations of daily fuel oil and LPG (liquid propane gas) consumption for a residential home, including a comparison of the annual winter heating costs for fuel oil, LPG, and the ATESS heating system using off peak electric and daytime solar, all off peak electricity, and all daytime solar;
• FIG. 11 shows an alternative arrangement of the ATESS installed in a dwelling having an oil or natural gas hot air furnace system; and
• FIGS. 12-15 illustrate four exemplary modes of operation of the ATESS ofFIG. 11.
DETAILED DESCRIPTION
• As previously noted, there are many sources of energy (e.g., solar, electrical, oil, gas, wind, etc.) which may be available for collection only during limited time periods during a 24 hour day. This is in contrast to the electrical, heating or cooling power needs associated with a residential or commercial building, which may vary during any given 24 hour period. The disclosed ATESS accommodates such limited availability of these energy sources and provides a steady source of energy, as needed, throughout a 24 hour period.
• Referring toFIG. 1, theATESS1 is shown installed in thebasement area2 of a dwelling having an oil or natural gas hotair furnace system4. TheATESS1 may comprise astorage tank6 containing a quantity of thermalenergy storage material8, a hotwater storage tank10 for heating and distribution of hot water through the residence, and aconnection12 between thestorage tank6 and thefurnace system4 to allow the transfer of heat between the thermalenergy storage material8 and thefurnace system4. Aconnection14 will also be provided between thehot water tank10 and thestorage tank6 to allow the transfer of heat between the thermalenergy storage material8 contained in thestorage tank6 and the hot water from thehot water tank10.
• Theconnection12 between thestorage tank6 and thefurnace system4 may comprise fluid supply and returnpiping16,18 which connect to opposite ends of acondenser coil20 located within thefurnace system4. Likewise, the supply and returnpiping16,18 connect to opposite ends of anevaporator coil22 located within thestorage tank6. The supply and returnpiping16,18 and condenser and evaporator coils20,22 thus form a closed loop for the movement of a heat transfer fluid between thefurnace system4 and the thermal energystorage material tank6. The flow rate of the heat transfer fluid may be controlled by operation of acompressor24 located in the return piping18, and acontrol valve26 located in thesupply piping16.
• Likewise, theconnection14 between the thermal energystorage material tank6 and thehot water tank10 may comprisesupply28 and return30 piping connected to aheating coil32 disposed within thestorage tank6. Water is pumped through the supply and returnpiping28,30 by acirculation pump34 located in the supply piping line. Acheck valve36 disposed within the discharge piping protects against backflow of water through the return piping when thepump34 is turned off. Thehot water tank10 may further have a coldwater supply line38 for providing a constant source of water to thetank10 for heating, and a hotwater discharge line40 for distributing the heated water throughout the residence.
• Thehot water tank10 may further have one or moreelectrical resistance heaters52,54 to heat the water in the tank to a desired temperature using building electricity.
• In operation, the water in thehot water tank10 is heated to a desired temperature using one or more of theresistance heaters52,54. The heated water may then be pumped through the supply and returnpiping28,30 to heat the thermalenergy storage material8 contained in the thermal energystorage material tank6. This heat transfer can occur until a desired amount of energy is contained in the thermalenergy storage material8.
• Thereafter, the energy contained in the thermalenergy storage material8 can be transferred to theair46 of thefurnace system4 via the fluid supply and returnlines16,18. The heat transfer fluid contained in these lines may be warmed as it passes through theevaporator coil22 andcompressor24. Energy contained in the heat transfer fluid is then transferred to the recirculatingair46 via thecondenser coil20, providingwarm air50 to be returned to the living space.
• The energy in the thermalenergy storage material8 can also be used to transfer energy back to the water in thehot water tank10, via the supply and returnpiping28,30 andrecirculation pump24. Thus, during off-peak periods (e.g., night time) the hot water system is used to transfer heat to the thermalenergy storage material8, allowing the storage of large quantities of heat during an otherwise light energy loading period. Thereafter, during peak loading periods (e.g., daytime), the heat can be transferred back to the hot water tank or to the furnace, as needed to heat the building air and/or water.
• In addition to thecondenser coil20 arrangement, thefurnace system4 may comprises atraditional fuel supply42, and a furnaceair circulation fan44 for drawingcold air46 from the livingspace48. Thefan44 causes thecold air46 to flow over the condensingcoil20, and then circulates theheated air50 throughout the livingspace48. In one embodiment, where the living space thermostat is set to about 70 degrees F., thecold air46 is at a temperature of about 65 degrees F., and thehot air50 is at a temperature of about 75 degrees F.
• One appropriate thermal energy storage material is that described in U.S. Pat. No. 3,976,584 to Leifer, the entire contents of which is incorporated by reference herein. The Leifer patent describes a clathrate material that is stable at atmospheric temperature and pressure, has a melting point higher than 32 degrees F., and has a relatively high specific heat and heat of fusion. Such a material absorbs heat until its temperature rises to its melting point. Because of its high heat of fusion, the thermal storage material can absorb a large quantity of heat per unit mass, making it a highly efficient means of energy storage. This is but one possible material that may be used as the thermalenergy storage material8, and other materials have properties that are expected to make them desirable for use as the thermalenergy storage material8. For example, materials such as imidazole, imidazolium chloride, derivatives of pyrrole, such as 2-acetyl pyrrole or tetra methylpyrrole, or other like compounds may be suitable for use as thermalenergy storage material8. The results of testing of certain of these thermal energy storage materials are discussed in relation toFIGS. 8-10C. Materials other than those specifically tested and/or identified may be suitable as well, as will be appreciated by one of ordinary skill in the art.
• Thetank6 employed to hold the thermal energy storage material will preferably be made of a material that is non-reacting when exposed to the particular thermalenergy storage material8 used in the ATESS. Thus, in one embodiment thetank6 may be made from polyethylene material. Alternatively, thetank6 may be made from glass or non-reacting material or may be provided with a glass or other non-reacting material lining such as polypropylene, fiberglass or Teflon.
• Like the tank interior, the external surfaces oflines22,32 that run within the tank should also be non-reactive when exposed to the particular thermalenergy storage material8 contained in thetank6. For embodiments in which lines22,32 comprise copper piping or tubing, the external surfaces may be coated with an acrylic paint and wrapped with a polymer wrap to prevent reaction between the thermalenergy storage material8 and the copper material. As an alternative to the polymer wrap, a paraffin material may be used as a coating over the acrylic coat. Paraffin is expected to work well where the operating temperature of the thermalenergy storage material8 is less than about 140 degrees F., since the melting point of paraffin is about 162-177 degrees F. As a further alternative,lines22,32 could be made from a polymer material, such as polyethylene (e.g., PEX tubing), polypropylene, fiberglass or Teflon. Additionally, polymer coated metal tubing may be used.
• Thetank6 and its connections should be sealed from the atmosphere to prevent the evaporation of water from the thermalenergy storage material8 during operation. Large-scale evaporation may cause undesirable changes in the thermal properties. Alternatively, evaporation may be compensated for by providing a level measurement scheme for thetank6 so that additional water can be added to the thermalenergy storage material8 when a minimum acceptable tank level is detected. Examples of suitable level measurement schemes may comprise a visual line-type indicator, as well as automated level detection systems. Additionally, in response to a low-level indication, supplemental water may be added manually by the user, or via an automated load leveling system.
• Lines22,32 should be arranged within thetank6 to serve the entire height of the tank (i.e., they should run almost to the bottom of the tank6) to avoid solid spots within the material during operation. Thelines22,32 can have a U-shaped configuration, or they may be coiled. It will be appreciated that the tubing configuration within the tank is not limited to U-shapes and coils, and that other appropriate shapes forlines23,32 may also be used.
• In one embodiment, thesurplus 220 Volt [V] off-peak electrical energy, which is only available for about eleven hours in the evening, provides the thermal energy for heating the home and hot water needs over a 24 hour day by maintaining all of the water in thehot water tank10 at about 120 degrees F. The 120 F hot water is circulated into atube heating coil32 installed in thetank6 used for storing the thermalenergy storage material8, thus transferring heat energy to the material8 (solid to liquid) at a constant 77 degrees F. melting point for storage. When the dwelling thermostat demands more heat, theATESS compressor24 and the furnaceair circulation fan44 starts. Therefrigerant control valve26 provides a 40 degrees F. vaporized refrigerant to theevaporator coil22 which absorbs heat from the 77 degrees F. thermal energy storage material. Thecompressor24 elevates the refrigerant temperature to 120 degrees F. to the condensingcoil20, which transfers the heat required at all times during a 24 hour day to the circulatingfurnace air46 for home heating. It is noted that this temperature scenario applies where the living space temperature (i.e., the thermostat set temperature) is 70 degrees F. Thus, where cooler or warmer living space temperatures are desired, the system operating temperatures will adjust accordingly.
• Referring toFIG. 2, an ATESS55 is shown installed in a dwelling having an oil or natural gas hotair furnace system4 similar to that described in relation toFIG. 1. In theFIG. 2 system, the energy from thefurnace system4 is supplemented with energy provided by one or more solar waterheating collector panels56. In the illustrated embodiment, a solar panel circulating water loop58 is integrated into the hot water return piping30 so that water from thehot water tank10 can be circulated through the solarenergy collector panel56. A solarpanel supply line60 connects to the hot water return piping30 between thecheck valve36 and thehot water tank10 to draw water from thetank10 and/or the output from theheating coil32. A solar panel circulation pump62 is disposed in thesupply line60 to provide the motive circulation force for the water. The pumped water passes through the internal passages (not shown) within thesolar panel56, and is heated by the direct energy of the sun. The energy produced by aphotovoltaic collector portion64 of thesolar panel56 is used to power pump62. The heated water then passes to areturn line66 which directs the water back to thehot water tank10. The heated water can then be passed through the supply and returnpiping28,30 usingrecirculation pump34 so that the heat from the water is transferred to the thermalenergy storage material8 in thetank6. It will be appreciated that thesolar panel56 may be used to supplement the heat provided by theelectrical resistance heaters52,54, or on days of particularly direct sunlight, may be used alone to heat the water in the hot water tank.
• The energy provided to the thermalenergy storage material8 is thereafter available for use to heat the recirculatedair46 of the furnace, or to heat the hot water contained in thehot water tank10.
• The remainder of the system55, including thestorage tank6, thermalenergy storage material8, and the connections between thestorage tank6, thehot water tank10 and thefurnace system4 may all be the same as described in relation to thesystem1 ofFIG. 1.
• In one embodiment, solar energy collected during sunny days as well as surplus off-peak electrical energy provided to theelectrical resistance heaters52,54 (which, again, may only be available for about eleven hours in the evenings,) provides the thermal energy to heat the home and hot water needs throughout a 24 hour day by maintaining all the water in thehot water tank10 at about 120 degrees F. The 120 degree F. hot water is circulated into thetube heating coil32 installed in the thermal energystorage material tank6, transferring heat energy to the thermal energy storage material8 (solid to liquid) at a constant 77 degree F. melting point for storage. When the dwelling thermostat demands more heat, theATESS compressor24 and the furnaceair circulation fan44 start. Therefrigerant control valve26 provides a 40 degree F. vaporized refrigerant to theevaporator coil22 which absorbs heat from the 77 degree F. thermalenergy storage material8. Thecompressor24 elevates the refrigerant temperature to 120 degrees F. to the condensingcoil20, which transfers the heat required at any time during a 24 hour day, to the circulatingfurnace air46 for home heating.
• Referring toFIG. 3, an ATESS68 is installed in a dwelling having an oil or natural gas hotair furnace system4 as well as a separate water heating system (i.e., a heat pump),72. The system ofFIG. 3 has substantially the same piping, components, and interconnections as described in relation to the system ofFIG. 1, but also includes aheat pump system72 that enables supplemental heating of the water in thehot water tank10 to accommodate high volume hot water needs during the day and/or night.
• Thus, the ATESS68 ofFIG. 3 comprises afurnace system4, thermal energystorage material tank6,hot water tank10, and all related piping and fluid management components described in relation toFIG. 1. As with the systems described in relation toFIGS. 1 and 2, the ATESS68 heats the thermalenergy storage material8 during off-peak hours by circulating hot water from thehot water tank10 through theheating coil32 in thestorage tank6.
• The ATESS68 further comprises an additionalclosed heating loop72 havingfluid supply74 and return76 piping in communication with respective evaporator and condenser coils78,80 located within the thermal energystorage material tank6 and thehot water tank10. Acompressor82 is located in thesupply line74 and provides the motive force for moving the heat transfer fluid (contained within the piping74,76) between the heat transfer coils78,80 in therespective tanks6,10, thereby transferring heat from the thermalenergy storage material8 to the hot water located in thehot water tank10. Acontrol valve84 is located within the return piping76 to control the flow rate of the heat transfer fluid, thus controlling the amount of heat transferred between the thermalenergy storage material8 and the water in thehot water tank10.
• As with the previously described embodiments, the surplus 220 V off-peak electrical energy, which is only available for about eleven hours during the evening, provides the thermal energy to heat the home and hot water over a 24 hour day by maintaining all the water in thehot water tank10 at about 120 degrees F. The 120 degree F. hot water (heated by theresistance heaters52,54) is circulated into aheating coil32 installed in the thermal energystorage material tank6, thus transferring heat energy to the thermal energy storage material (changing it from solid to liquid) at a constant 77 degrees F. melting point for storage. When the dwelling thermostat demands more heat, theATESS compressor24 and the furnaceair circulation fan44 starts. Therefrigerant control valve26 provides a 40 degrees F. vaporized refrigerant to theevaporator coil22 which absorbs heat from the 77 degree F. thermalenergy storage material8. Thecompressor24 elevates the refrigerant temperature to 120 degrees F. to the condensingcoil20, which transfers the heat required at all times of a 24 hour day, to the circulating furnace air for home heating. Theheat pump system72 is operable to heat water in thehot water tank10 at any time of the day, using the stored heat in the thermalenergy storage material8.
• Referring toFIG. 4, ATESS system86 is installed in a dwelling having an oil or natural gas hotair furnace system4, and which has a separate water heating system (i.e., a heat pump)78 similar to that described in relation to the ATESS ofFIG. 3. In the embodiment ofFIG. 4, however, the ATESS86 is configured with a control system87 that may reverse the functions of the components to enable the ATESS86 to heat or cool the house as desired. Thus, on hot, humid summer days, the ATESS86 removes heat from thehouse circulating air88, and stores that heat in the thermalenergy storage material8 for heating water for home use or home heating. The cooledair90 is then recirculated through the dwelling.
• The ATESS86 ofFIG. 4 comprises afurnace system4, thermal energystorage material tank6,hot water tank10, as well as all related piping and fluid management components described in relation toFIG. 3. As noted, the ATESS86 further comprises a control system87 operable to reverse the flow of heat transfer fluid between thestorage tank6 and thecoil20 of thefurnace system4. This flow reversal may be implemented by providing an appropriate piping arrangement for redirecting the flow of the heat transfer fluid according to a desired series of valve settings. Thus, in a “heating” setting, the flow of heat transfer fluid would be throughlines16 and18 in the direction of arrows “A,” and would be functional for heating thedwelling air88. In the “cooling” setting, the flow of heat transfer fluid would be throughlines16 and18 in the direction of arrows “B,” and would be functional for cooling thedwelling air88. Suitable electronics may be provided to automatically actuate and control the direction and flow rate of the heat transfer fluid throughlines16 and18.
• Where the system86 is used for cooling thedwelling air88, particularly during the hot summer months in southern portions of the northern hemisphere, an outdoor evaporator coil and fan may be provided in communication with the heattransfer storage material8. This arrangement may be of advantage where the thermalenergy storage material8 has met its maximum capacity for storage of rejected air conditioning heat, since it provides a path for rejecting excess heat to the outdoors.
• In an alternative embodiment, in lieu of a special piping arrangement for redirecting flow,compressor24 could be a reversible compressor, and controlvalve26 could be of a design that provides a desired degree of flow control regardless of the direction of flow past the seat. Additionally, in lieu of control valve26 a pair of control valves could be provided, one for controlling refrigerant flow rate when heat is needed in winter or on cool summer evenings, and a second to control refrigerant flow if heat needs to be removed from the dwelling in the summer. Suitable known control electronics may be provided to enable automatic selection of a flow direction.
• As with the previously-described embodiments, the ATESS86 ofFIG. 4 operates to store energy in the thermalenergy storage material8 during periods in which such storage is most efficient. In one embodiment, energy removed from thehot air88 of the living space is transferred to thestorage material8 via thecompressor24,control valve26 and piping16,18 arrangement previously described. The stored energy may then be used to heat water (in a manner previously described) immediately or at a later time, or to heat the air circulated through thefurnace system4 at a later time, as needed.
• Referring toFIG. 5,ATESS system92 has substantially the same piping and components as the system68 described in relation toFIG. 3, and further comprises one or more photovoltaicsolar collection panels94 to provide additional water and air heating for cold weather operation, such as in winter. The one or moresolar collection panels94, employing known photovoltaic principles, may produce direct current (DC) electricity, which may then converted to alternating current (AC) electricity by a suitable AC/DC converter96. The resulting AC electricity may then be connected to the appropriate home or building power supply circuits. A step-up or step down converter (not shown) may also be required to match the home or building power supply circuit. The electricity from thesolar panels94 may be provided directly to theresistance heaters52,54 that provide thermal energy to the water contained in thehot water tank10. This energy may then be transferred to the thermal energy storage material vialines28,30 andheating coil32, in a manner previously described in relation to the systems ofFIGS. 1-4.
• The system ofFIG. 5 is particularly well suited to use in cold weather regions. Thus, when the cold weather season arrives, the available daytime solar power generated by thesolar collection panels94 may be used to heat water in the hot water tank for house use, and also to store the (now converted) electrical energy in the thermalenergy storage material8 usingATESS92. TheATESS92, in a manner similar or identical to that described in relation toFIG. 3, may then be used to heat the home and to meet hot water needs during any portion of a 24 hour day. The off-peak surplus electric power would be back-up energy during cloudy or limited sunny days for the net thermal energy needed to heat the residential dwelling or commercial building and/or water.
• Referring toFIG. 6,ATESS system98 has substantially the same piping and components as the ATESS86 described in relation toFIG. 4, and further comprises one or more photovoltaicsolar collection panels100 for hot summer weather operation. The one or more solar collectingpanels100 using known photovoltaic principals, may generate direct current (DC) electricity, which may then be converted to alternating current (AC) using avoltage converter102, thus enabling connection with the home or building electric power supply. When the hot, humid, weather season arrives, the electric power generated by thesolar collection panels100 may be used to operate the conventional air conditioning system, which operates in conjunction with the reversible ATESS86 system described in relation toFIG. 4 to cool theair88 in the living space.
• Astorage tank6 for use in a typical dwelling may be approximately 400 gallons in volume, and may contain an energy storage material such as that described in U.S. Pat. No. 3,976,584 to Leifer. Other appropriate thermal energy storage materials may be tetra iso-amyl ammonium fluoride.38H₂0, tetra n-butyl ammonium fluoride. 18H₂0 (Clathrate Materials). Additionally, the following Non-Clathrate Materials may also be used: imidazole, imidazolium chloride, derivatives of pyrrole, such as 2-acetyl pyrrole or tetra methylpyrrole, or other like compounds. The heating coils22,32,78 may be made of corrosion resistant materials suitable for carrying approximately 120 degree F. water in operation. The total heat stored in the approximate 400 gallons of thermal heat storage material would heat a home of approximately 1600 square feet of living space maintaining a temperature of approximately 70 degrees F. in the most northern latitudes of the United States daily throughout the year. The heat stored in the approximate 400gallon tank6 of thermalenergy storage material8 for heating the home would also heat water in an approximate 60 gallon insulatedhot water tank10 to a desired 115 degrees F. to 120 degrees P temperature for normal family hot water usage.
• The ATESS may be provided with an appropriate computer control system for controlling theheat pump system72,furnace system4, recirculation pumps34,62compressor24,control valve26, andresistance beaters52,54 to enable the ATESS to perform as desired to compliment the oil or natural gas heating system and/or water heating system needs of a commercial or residential building. The control system would also control the dwelling heat transfer (i.e., heat pump) system as a dual system to remove heat from the air circulating in the furnace duct system during the hot and humid summer days, and to that heat in the thermal energy storage material stored in thestorage tank6. The system may be used in conjunction with a conventional electric powered air conditioning system during the hot-humid summer months.
• It will also be appreciated that the ATESS may be integrated into a mobile platform to aid in the transport of perishable commodities such as orange juice and the like. Thus, the ATESS may be sized and configured for installation in railroad cars, trucks, planes, container/cargo ships or other transportation platforms. In one example, the ATESS may be combined with solar panels or fuel oil to reduce oil consumption in ocean going passenger ships.
• Further, the ATESS may be used as part of a system for reducing the energy consumption required for any of a variety of industrial processes that require substantial energy, such as soup making, and the like.
• In yet another embodiment, the ATESS may be used to advantage in applications such as commercial/personal ice skating or hockey rinks.
• Advantages
• The Northeast area of the United States has the larger number of homes and commercial buildings heated by oil and liquefied natural gas (LPG). Due to the lack of major natural gas pipelines serving the area, liquefied natural gas is imported through major seaports in the Northeast by huge tankers from foreign countries, which could be a terrorist threat to the security of our seaports. The conversion to ATESS of homes and commercial buildings to electric off peak power or solar energy would eliminate these shipments and the associated threats to our seaports.
• The United States currently imports approximately 40% of its domestic oil needs from foreign countries. The ATESS system can substantially reduce or eliminate the need for foreign oil.
• ATESS can also reduce the need to heat residential dwellings or commercial buildings with oil and natural gas. ATESS can reduce daytime peak electric power demands during hot and humid weather.
• ATESS can store solar thermal energy available during the daytime for use during day or night for energy needs of residential dwellings or commercial buildings.
• ATESS, if widely used in residential dwellings and commercial buildings, will allow electric power generation networks to practice load leveling between peak daytime and surplus off-peak night time electric power demands.
• Laboratory Test Results for Various Thermal Energy Storage Materials
• The inventors have conducted laboratory tests to determine the melting point, heat of fusion and safe operating temperature range of several materials considered suitable for use as thermalenergy storage material8. The results of the inventors' tests are shown in Table 1 below. In addition to the specific clathrate material the inventors used in their tests, other potentially useful clathrate materials exist and are noted herein. These materials include: tetra iso-amyl ammonium fluoride 38H₂O, which has a melting point of 88 degrees F., and tetra n-butyl ammonium fluoride 18H₂O, which has a melting point of 98.6 degrees F. It should be noted that some of the other thermal energy storage materials identified in Table 1 below have melting points much greater than 77 degrees F. The use of these higher melting point materials in any one of the previously described ATMSS systems may preclude the need for aheat pump system72.

• TABLE 1
  Physico-Chemical Results of Potential Tested
  Thermal Energy Storage Materials

  		Heat of	% Heat of	Safe Operating
  	Melting Point	Fusion	Fusion of	Range
  Materials	(degrees F.)	(BTU/lbs)	Water (%)	(degrees F.)

  TESM 11	77	108	75%	77-140
  Imidazole	194	75	52%	194-320
  Imidazolium	320	60	42%	320-375
  Chloride
  2-Acetylpyrrole	195	77	54%	195-260
  Note that the “Safe Operating Range” indicated in Table 1 represents, for each TESM, a temperature range between the melting point of the TESM and a point approximately 5-20 degrees F. below the decomposition temperature of the particular TESM.
  1“TESM 1” was (n-C4H9)4NF32.8H2O

• Test Site Results
• Referring toFIG. 7, a test site building was constructed as a horizontal duplex, with each room (Rooms #1 and #2) being approximately 32 square feet.Room #1 was heated conventionally, whileRoom #2 was heated using the ATESS. The inventors used 40 lbs of Thermal Energy Storage Material (TESM) 8, which in this case was (n-C₄H₉) 4NF 32.8H₂O, and which will be referred to hereinafter as “TESM1.” TheTESM1 was contained inTESM1tank6. For the purposes of the test, thetank6 was a 5 gallon polyethylene tank. Internal piping was copper, coated with acrylic coating and wrapped with a polymer film. Thetank6 connections were sealed from the atmosphere using tape to prevent evaporation. The 40 lbs. ofTESM1 stored heat energy from two (2) limited sources in these tests.Source 1 was evening off peak electricity andSource 2 was daytime solar energy. The solar heat collection system worked well, but due to the lack of sunny days during, the test, the inventors simulated the daytime solar heat by using metered daytime electric power. Both sources were limited to four (4) hours per cycle for the tests. The ATESS inRoom #2 was a scaled down version of the ATESS previously described in relation toFIG. 2.
• FIG. 8 shows the results of 14 days of testing.Days 1, 2, and 3 were conducted to determine the heat required to maintain a consistent temperature inRooms #1 and #2. The results of these tests show the heat required to maintain the same temperature inRooms #1 and #2 are essentially the same.
• FIG. 8 also showstest days #4 through #14 which were conducted using only the ATESS heating system as a primary heat source forRoom #2.Test days #4 and #5 were not considered in the results because those days used 3.0 and 3.5 hour heating cycles to transfer heat to the TESM, and these shorter cycle times were deemed not to be long enough for transfer of an adequate amount of heat toTESM1 for storage during the tests. The remaining test days (#6 to #14) used four (4) hour TESM heating cycles. The results show that ATESS heating system works very well to maintain the temperature inRoom #2 at a nominal 70 degrees F. (temperature actually ranged from about 68-71 degrees F.) without the use of any conventional additional heat from fuel oil or gas. During the December and January tests, the outside air temperature fluctuated from a low of 12 degrees F. to a high of 47 degrees F.
• FIG. 9 shows the performance of the ATESS heating system hour by hour during a 24-hour day. The results inFIG. 9 were compiled for an optimum day (i.e., one close to the mean of test days 6-14) using the ATESS. The results show energy from two (2), limited sources (i.e., evening off peak electricity and daytime solar) being distributed as needed to testRoom #2 in order to maintain a desired temperature. Some heat from the ATESS control system, compressor motor losses, and heat of compression from the compressor were also added toRoom #2. The limited source energy from non-peak electric and solar was stored in theTESM1 during the limited 4 hour cycles and then distributed toRoom 2 by the ATESS heat pump system. The heat needed to maintain 70 degrees F. inRoom 2 was controlled by the thermostat of the ATESS system.
• The results tabulated inFIGS. 8 and 9 show heat pump inefficiencies of our system design which can be substantially improved by an experienced heating and ventilation equipment manufacturer. For example, the ATESS system prototype heat pump evaporator coil comprised single diameter copper tubing. An experienced HVAC engineer could design an evaporator coil having a varied diameter in order to maintain a constant evaporator refrigerant temperature of approximately 40 degrees F. across the entire coil. Additionally, the prototype heat pump system had less than optimal electric compressor motor efficiency, which may be improved greatly in large system designs using either AC or DC electric power. Additionally, modern control systems applied to a large-scale ATESS would use little electric power as compared to the prototype system. The ATESS heating system inefficiency is indicated inFIGS. 8 and 9 as extra heat added to room #2 (“Motor Loss and Extra Room Heat Demand”) to maintain the desired temperature.
• The inventors consider that to install an operational. ATESS into a full size residential home having 1600 sq ft. of living area would require a 50:1 scale up to replicate the results shown at the test site.FIGS. 10A-C show the daily fuel oil and LPG (liquid propane gas) consumption for such a residential home. In addition,FIGS. 10A-C shows a comparison of the annual winter heating costs for: a) fuel oil, b) LPG, and c) the ATESS heating system using: 1) off peak electric and daytime solar, 2) all off peak electricity, and 3) all daytime solar.
• The results indicate a substantial cost savings can be achieved through use of the ATESS. For example, the annual cost for fuel oil using a 125 day annual winter heating cycle is estimated to be about $1,813, while the annual cost for LPG also using a 125 day annual winter heating cycle is estimated to be $1,932. (These estimated costs where calculated using estimates of $2.55/gallon of fuel oil and $1.86/gallon of LPG.) By comparison, the annual heating cost using the ATESS for the 125 day annual winter heating cycle with: 1) off peak electric and daytime solar is estimated to be about $1,048; 2) all off peak electric is estimated to be about $1,348; and 3) all daytime solar is estimated to be about $748. Thus, it can be seen that there would be a considerable savings with the use of the ATESS as compared to conventional heating methods. This savings can be increased by adding accessories to heat water.
• For example, during hot summer months, heat may be removed from the dwelling space (via air conditioning) and stored in the TESM. Appropriate piping and pumping equipment (e.g.,items72,83 inFIG. 4) may be added to the ATESS to allow transfer of this stored heat from theTESM8 to the hot water in thehot water tank10 to maintain a desired temperature (e.g., 125 degrees F.). Heating the hot water in this manner may eliminate or reduce the need to use expensive daytime electric, fuel oil or LPG.
• FIGS. 10A-C further show the gallons per day of fuel oil and LPG as well as the total annual costs for a 125 day winter heating season.
• In addition to the aforementioned cost savings, the use of the ATESS may also result in substantial reductions in pollutants emitted to the atmosphere as compared to conventional heating systems. For example, the burning of fuel oil (for the annual heating season) emits to the atmosphere 3,831 lbs of carbon and 14,060 lbs of CO₂per residence (again assuming a 1600 square foot living space). The burning of LPG emits 2,927 lbs of carbon and 10,742 lbs of CO₂, for the same size living space. The ATESS, by contrast, emits no carbon or CO₂to the atmosphere from the residences. These results are clearly shown at the bottom ofFIG. 10C.
• Referring now toFIG. 11, an alternative arrangement for theATESS200 is shown installed in dwelling having a heating, ventilation and cooling (HVAC)system202. As with the previous embodiments, theATESS200 may comprise astorage tank204 containing a quantity of thermalenergy storage material206, a hotwater storage tank208 for heating and distribution of hot water through the residence, and connections between thestorage tank204 and theHVAC system202 to allow the transfer of heat between the thermalenergy storage material206 and theHVAC system202. Connections may also be provided between thehot water tank208 and thestorage tank204 to allow the transfer of heat between the thermalenergy storage material206 contained in thestorage tank204 and the water in thehot water tank208.
• Thestorage tank204 and the thermalenergy storage material206 used with theATESS200 ofFIG. 11 may be the same as thestorage tank6 and the thermalenergy storage material8 described in relation to theATESS1 ofFIGS. 1-10.
• As can be seen inFIG. 11, one difference between theATESS200 ofFIG. 11 and theATESS1 ofFIGS. 1-10 is that thestorage tank204 does not have an evaporator coil (i.e.,coil22 inFIG. 1) disposed inside the tank This arrangement protects the TESM from overheating by assure that the 140 F deterioration limit of the TESM will not be reached during normal operation of the system.
• Thestorage tank204 does have a connection to theHVAC system202, comprising afluid loop210 located within thetank204, fluid supply and return piping212,214 which connect to opposite ends of afirst coil216 located within theHVAC system202. Afirst pump218 located within thesupply piping212 is controllable to circulate fluid within the loop to transfer energy between the thermalenergy storage material206 and theHVAC system202. Thefirst pump218 may be a variable speed pump that enables precise control of the flow rate of the fluid within the loop. Although the system has been described as using water as the circulated “fluid,” it will be appreciated that other fluids may be used depending upon the application of the system. For example, ethylene glycol, mineral oil, Dow-Therm and the like can be used as the circulated fluid where theATESS200 will not be used for providing hot water service (e.g., tap, cooking, or cleaning uses) to the building in which the system is installed.
• As an additional measure of protection against exceeding the deterioration limit of the thermalenergy storage material206, thestorage tank204 may have a temperature sensor. This temperature sensor may be operable to signal the shutdown of thefirst pump218, and to signal theHVAC system202 to remove heat from the dwelling air and to exhaust the heat to the outside of the dwelling. It will be appreciated that one or more temperature sensors may also be provided to measure the temperature of the fluid within thesupply piping212.
• Thehot water tank208 may have aninlet connection220 for receiving fill water from a city water or other appropriate water supply connection, and anoutlet connection222 for providing heated water for home hot water uses. Theinlet connection220 may have acheck valve224 disposed therein to prevent backflow from the tank to the water supply line. Thehot water tank208 also may be connected to theHVAC system202 to enable the transfer of energy between the tank and the HVAC system. This connection may comprise first andsecond tank connections226,228, and first and second fluidloop piping legs230,232 which connect to opposite ends of asecond coil234 located within theHVAC system202. Asecond pump236 located within the second fluidloop piping leg232 is controllable to circulate water within the loop to transfer energy between thehot water tank208 and theHVAC system202. Thesecond pump236 may be a variable speed pump that enables precise control of the flow rate of the water within the pipinglegs230,232.
• Thehot water tank208 and thestorage tank204 may also be connected to enable the selective transfer of energy between the thermalenergy storage material206 in thestorage tank204 and the water in thehot water tank208. To this end, a first three-way valve238 may be disposed within the first fluidloop piping leg230. The first three-way valve238 may be operable to allow flow through the first fluidloop piping leg230 to provide flow from thehot water tank208 to thecoil234 located within theHVAC system202. The first three-way valve238 may also be provided with afirst circulation leg240 that connects an outlet port of thevalve238 to the fluid return piping214 of thestorage tank204 to enable circulation of water between thehot water tank208 and thestorage tank204. Similarly, a second three-way valve242 may be disposed in secondfluid piping leg232, and may be operable to allow flow through the second fluidloop piping leg232 to provide flow between thehot water tank208 and thecoil216 located within in theHVAC system202. The second three-way valve242 may also be provided with asecond circulation leg244 that connects an outlet port of thevalve242 to fluid supply piping212 of thestorage tank204 to enable the circulation of water between thehot water tank208 and thestorage tank204. In the illustrated embodiment, the first and second three-way valves are solenoid valves that may be remotely or locally operable using a manual or automated control system.
• Thehot water tank208 may additionally have one or moreelectrical resistance heaters246,248 to heat the water in the tank to a desired temperature using building electricity.
• Energy may be transferred between the HVAC system, thestorage tank204, and thehot water tank208 via a plurality of coil sets. Specifically a first coil set250 is positioned in thermal communication withfirst coil216, while a second coil set252 is positioned in thermal communication withsecond coil234. A third coil set254 is positioned within asupply duct256 of theHVAC system202 to heat or cool air being provided to the living spaces viafan257. Acompressor258 with associated piping and valves is provided for transferring energy: (1) from the first or second coil sets250,252 to the third coil set254, or (2) from the third coil set254 to the first or second coil set250,252. In this way, energy can be transferred between the air in thesupply duct256 and thehot water tank208 or thestorage tank204.
• It will be appreciated that although the coil pairs216/250,234/252 are shown as being separate and discrete coils, that they will often constitute opposing heat transfer paths within a single fluid-to-fluid heat exchanger. Likewise, third coil set254 will often constitute a fluid-to-air heat exchanger.
• First and second HVAC three-way valves260,262 may be provided in the compressor piping264 to facilitate selectable circulation between: (a) the first coil set250 and the third coil set254, or (b) the second coil set252 and thethird coil set254. In one embodiment, the HVAC three-way valves260,262 comprise solenoid actuated valves to enable automatic or manual remote control of the system.
• In practical use, the thermalenergy storage material206 may be delivered in liquid form by an over the road tanker from a chemical plant where it is manufacture. A special self-sealingfill nozzle266 may be provided near the top of thetank204. Thisfill nozzle266 may allows speedy filling and sealing, thus minimizing evaporation of the thermal energy storage material. Likewise, thetank204 may have a lowlevel drain nozzle268 with a drain valve installed near the bottom of the tank so that an over the road tanker can pump the thermalenergy storage material206 out of thestorage tank204 and transport it to a local distributor service center to be recrystallized and reused.
• As disclosed, theATESS200 has a multiplicity of operating configurations that result in a highly flexible energy storage and transfer system. Referring now toFIGS. 12-15, several exemplary modes of operation of theATESS200 will now be described in detail. Specifically,Mode 1, described in relation toFIG. 12, shows an exemplary configuration of theATESS200 as an off-peak heating system during the Winter season.Mode 2, described in relation toFIG. 13, shows an exemplary configuration of theATESS200 for use during the peak heating cycle, again during the Winter season.Mode 3, described in relation toFIG. 14, is for use of the ATESS in a water heating cycle, for all seasons.Mode 4, described in relation toFIG. 15, is for use of the ATESS as part of a renewable energy cycle, for warn weather seasons.
• Off-Peak Heating System (Winter Season)
• Referring toFIG. 12, in this mode, the storage of “off-peak” (eleven hours) surplus electric energy is supplied first to thehot water tank208 via the electricresistor heating elements246,248 controlled by a timer.First pump218 circulates approximately 125° F. water from thehot water tank208 to thestorage tank204 via a loop comprising first three-way valve238,first circulation leg240, fluid return piping214,fluid loop210,fluid supply piping212,second circulation leg244, second three-way valve242 and second fluidloop piping leg232. The heat from the “off peak” surplus electricity is transferred through thefluid loop210 for storage in the thermalenergy storage material206. The cooled water (i.e., from the outlet of fluid loop210) than is circulated back to thehot water tank208 for further addition of heat to be stored in the thermal energy storage material for the remainder of the limited “off-peak” 8 hour time period. The water in thehot water tank208 is available for use during the “off-peak” period and is ready for the early morning part of “peak” activities at 8 am.
• TheHVAC system202 may not operate during the “off peak” hours for space heating or water heating. Space heating is provided by electricresistance heater element280 in theductwork256 wherecool return air282 is circulated by thevariable speed fan257 in the heat pump unit housing. This electric ductresistance heating element280 is available again by timer for automatic actuation during this “off peak” period.
• The “off-peak” heat stored in the thermal energy storage material for water and space heating is then charged to the dwelling owner by the electric utility server at the base low cost rates. When the “off-peak” timer shuts off all electric power to theATESS200, the system controls would automatically switch toMode 2, to be described next.
• Peak Heating Cycle—Winter Season
• Referring toFIG. 13, in the Peak Heating Cycle mode mode, the “peak” period (eleven hours) space heating is provided by the “off peak” electric heat stored in the thermal energy storage material that was stored in the storage tank during the “off peak” hours.
• Thefirst pump218 pumps warm water heated by the 77° F.-115° F. thermalenergy storage material206 through thefirst coil216, which transfers the “off-peak” stored electric energy to the first coil set250 in theHVAC system202. Thecompressor258 transfers the heat as a high pressure refrigerant to the third coil set254 in thesupply air ductwork256, which heats the air provided to the living space. The hot air circulated to the living space will control the space heating temperature at 70 F. The cooled refrigerant from the third coil set254 is then returned to the first coil set250 to remove more heat from thefirst coil216 in which water heated via the thermalenergy storage material206 is being circulated.
• Thefirst pump218 circulates cooled water throughreturn line214 back to thestorage tank204 to remove more heat from the “off-peak” electric energy stored in the thermal energy storage material to provide space heating as previously described. It is contemplated that water heating may be needed during the active “peak” daytime hours, at which time the system operate inMode 3, to be discussed next.
• Water Heating Cycle—All Seasons
• Referring toFIG. 14, in the Water Heating Cycle mode, the peak water heating:period (9:00 a.m. to 11:00 p.m.) water heating is provided by “off peak” electric or summer “renewable energy” obtained from air conditioning heat stored in the thermalenergy storage material206 stored in thestorage tank204.
• Thefirst pump218 circulates warm water heated by the 77° F.-115° F. thermal energy storage material via212 throughfirst coil216 and then back to the storage tank via the fluid return piping214 andfluid loop210, in the process transferring heat fromfirst coil216 to the fluid in thefirst coil set250. This transfers the “off-peak” stored electric energy charged to the thermalenergy storage material206 to the fluid in thefirst coil set250. Thecompressor258 and first and second HVAC three-way valves260,262 transfer this heat received via first coil set250 as a high pressure refrigerant to thesecond coil set252. The hot second coil set252 then interfaces withsecond coil234 associated with thefirst pump218. Thesecond pump236 circulates relatively cool water from the bottom of thehot water tank208 throughsecond coil234 to heat the water using heat gained from the second coil set252, thus maintaining the hot water temperature for dwelling use of 125° F. or as desired.
• The modes of operation described thus far mainly address cold weather needs. During the hot summer weather, air conditioning of living spaces often is of prime importance. The summer air cooling needs are provided by conventional air conditioning units which reject the heated air to the outdoors. During any day in which air conditioning is required, the ATESS “Renewable Energy Cycle,”Mode 4, can be put into operation, as will be described next.
• Renewable Energy Cycle—Warm Weather Seasons
• Referring toFIG. 15, when operating in this mode, the high peak cooling period (4:00 pm-6:00 pm) summer water heating needs will be provided using air conditioning heat normally rejected to the outdoors. This may be accomplished by operating in the “renewable energy cycle” mode using theATESS system200 like an air conditioner and storing this renewable energy in the thermalenergy storage material206.
• TheHVAC system202 is engaged in the cooling mode by reversal of thecompressor258, theexpansion control valve259, first coil set250 and the third coil set254 from that of the winter heating mode. The third coil set254 disposed in thesupply air duct256 helps to maintain the cooling space temperature at 76° F. The normally rejected air conditioned heat energy is transferred from the third coil set254 to thefirst coil set250. This heat is then transferred to the cool circulating water flowing throughfirst coil216. Thefirst pump218 transfers the now-heated circulating water via the fluid return piping214 andfluid loop210 to the thermalenergy storage material206 for storage. This stored heat, which is wasted with typical systems, is then used to heat dwelling water stored in thehot water tank208 as described in the previous mode.
SUMMARY
• The inventors have shown that using the disclosed ATESS heating system as a compliment or a primary heating system:
• (1) Substantially reduces the need for fuel oil and/or liquid petroleum gas (LPG) for heating homes or industrial buildings.
• (2) Substantially reduces both carbon and carbon dioxide (CO₂) emissions which contributes to global warming.
• (3) Substantially reduces the need to transport surplus generated off peak electrical power from local grids, because it can be stored in the TESM for use at anytime during a 24-hour day.
• (4) ATESS heating systems allow for the use of solar energy obtained during daylight hours and stored in the TESM for use anytime during a 24-hour day.
• (5) ATESS heating systems, would transition home heating systems to electric as their primary energy source. This would reduce the country's dependence on foreign oil and LPG, thereby improving homeland security.
• Although the invention has been described in terms of exemplary embodiments it will be apparent to those skilled in the art that various changes and modifications can be made thereto without departing from the spirit and scope of the invention.

Claims (22)

1. A tank for storing a thermal energy storage material, comprising:

an outer shell and an inner surface, the inner surface defining a volume for accepting a quantity of thermal energy storage material;

heat exchange piping disposed within the volume for transferring heat between the thermal energy storage material and a fluid disposed within the heat exchange piping;

fill and drain connections;

wherein the fill and drain connections seal the volume from the outside atmosphere to prevent evaporation of the thermal energy storage material contained therein; and

wherein the inner surface of the tank and the outer surfaces of the heat exchange piping comprise a non-reactive material.

2. The tank ofclaim 1, wherein the heat exchange piping comprises a polymer material or a metal material having an outer polymer layer.

3. The tank ofclaim 1, wherein the inner surface of the tank comprises a material selected from the list consisting of polyethylene, glass polypropylene, fiberglass and Teflon.

4. The tank ofclaim 1, wherein the heat exchange piping comprises copper or other high heat transfer material coated with an acrylic layer or other non-reactive coating material.

5. The tank ofclaim 1, further comprising a level measurement system for providing an indication of a level of the thermal energy storage material disposed within the tank.

6. The tank ofclaim 1, wherein the level measurement system comprises a visual indicator or an automated level detection system.

7. The tank ofclaim 6, further comprising an automatic load leveling system that automatically adds a quantity of water in response to a predetermined low level reading from the level measurement system.

8. The tank ofclaim 1, wherein the heat exchange piping is arranged within the tank in a configuration selected from the list consisting of U-shaped and coiled.

9. The tank ofclaim 1, further comprising an electric resistance heater or other energy source for heating the thermal energy storage material.

10. The tank ofclaim 1, further comprising a removable lid that provides access to the volume.

11. A thermal energy storage system comprising:

a water tank for holding a quantity of water;

a storage tank having a quantity of thermal energy storage material disposed therein, the thermal energy storage material comprising a substantially solid material having a melting point above 32 degrees Fahrenheit (F) and a latent heat of fusion approaching that of water;

a first circulation loop comprising a first loop section disposed within the second tank and a second loop section in thermal communication with a first coil of a heating, ventilating and air conditioning (HVAC) system, the first circulation loop further having a first pump for circulating water between the first and second loop sections;

a second circulation loop comprising a first connection to the water tank, a third loop section in thermal communication with a second coil of the HVAC system, a second connection to the water tank, and a second pump for circulating water between the water tank and the third loop section; and

third circulation loop piping connecting the water tank and the storage tank, the third circulation loop having first and second valves disposed therein, the first and second valves being operable to provide selective fluid communication between the third circulation loop and the first and second circulation loops.

12. The system ofclaim 11, wherein the system has a first configuration in which the first and second valves are aligned so that the first pump circulates water between the third circulation loop piping and portions of the first and second circulation loop to transfer heat from the water in the water tank to the thermal energy storage material disposed within the storage tank.

13. The system ofclaim 11, wherein the system has a second configuration in which the first and second valves are aligned so that the first pump circulates water within the first circulation loop to transfer heat from the first coil of the HVAC system to the thermal energy storage material in the storage tank.

14. The system ofclaim 1, wherein the system has a third configuration in which the first and second valves are aligned so that the first pump circulates water within the first circulation loop to transfer heat from thermal energy storage material to the first coil of the HVAC system, and the second pump circulates water within the second circulation loop to transfer heat from the thermal energy storage material to the second coil of the HVAC system.

15. The system ofclaim 11, wherein the HVAC system further comprises a compressor, first and second HVAC valves, an HVAC piping loop, and a third coil disposed in a ventilation duct for transferring energy between air in the ventilation duct and the third coil.

16. The system ofclaim 15, wherein the first and second HVAC valves are selectively operable to form a first HVAC loop between the first coil and the third coil, and a second HVAC loop between the second coil and the third coil.

17. The system ofclaim 16, wherein said compressor is a reversible compressor.

18. The system ofclaim 15, further comprising a temperature sensor associated with the storage tank, wherein when the temperature sensor senses that the temperature of the TESM exceeds a predetermined temperature limit, the temperature sensor is operable to send a signal which causes the first pump to be turned off and the HVAC system to be turned on.

19. The system ofclaim 11, wherein the first and second pumps are variable speed pumps.

20. The system ofclaim 11, wherein the first and second valves are three-way solenoid valves.

21. The system ofclaim 10, wherein the first coil and the second loop section of the first recirculation loop comprise a first heat exchanger, and the second coil and the third loop section of the second recirculation loop comprise a second heat exchanger.

22. The system ofclaim 10, wherein the thermal energy storage material is selected from the list consisting of clathrate, imidazole, imidazolium chloride and a derivative of pyrrole.

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