US20060201175A1 - Strategic modular refrigeration system with linear compressors - Google Patents

Abstract

A modular commercial refrigeration unit constructed and arranged for placement in strategic proximity to a plurality of associated product cooling zones within a shopping area includes a refrigeration rack proximate to a shopping area and configured to accommodate maximum refrigeration loads of the associated product cooling zones. The refrigeration rack has an optimum footprint. The refrigeration rack is constructed to support components of a closed refrigeration circuit including associated high side and low side refrigerant delivery and suction means extending from the rack and being operatively connected to a plurality of evaporators for cooling the associated product cooling zones. The modular refrigeration unit also includes a linear compressor and a cooling source remote from the refrigeration unit that provides a cooling relationship with a condenser for providing optimum condensing and efficiency of the evaporators in cooling the associated product cooling zones.

Description

BACKGROUND
• The present invention relates to commercial refrigeration systems, and in particular, commercial refrigeration systems having at least one linear compressor.
• Commercial refrigeration systems have traditionally been accomplished via centralized parallel compressor systems with long liquid and suction branches piped to and from the evaporators in the refrigerated display cases. As an alternative, centralized parallel rack refrigeration systems have been developed for cooling a plurality of fixtures in multiple cooling zones within a shopping area. Another alternative is a self-contained, refrigeration display merchandiser including multiple horizontal scroll compressors.
• A disadvantage to all these systems is the use of scroll compressors within the commercial refrigeration systems. Scroll compressors generate too much acoustic noise for the shopping area of a store and do not allow for variable capacity control of the refrigeration system. Because of the lack of variable capacity control, the compressor may perform unnecessary cycling, which may be detrimental to the stored commodity (e.g., sensitive food products) refrigerated by the merchandisers or refrigerated display cases. Further, scroll compressors use oil for operation, which results in inefficient performance due to oil film on evaporator and condenser surfaces, requires the use of expensive oil management components, and increases the installation cost of the refrigeration system.
• It would be beneficial to have another alternative to the above systems and units utilizing scroll compressors.
SUMMARY
• In one embodiment, the invention provides a modular commercial refrigeration unit constructed and arranged for placement in strategic proximity to a plurality of associated product cooling zones within a shopping area. The modular refrigeration unit includes a refrigeration rack proximate to a shopping area and configured to accommodate maximum refrigeration loads of the associated product cooling zones. The refrigeration rack has an optimum footprint. The refrigeration rack is constructed to support components of a closed refrigeration circuit including associated high side and low side refrigerant delivery and suction means extending from the rack and being operatively connected to a plurality of evaporators for cooling the associated product cooling zones. The modular refrigeration unit also includes a linear compressor and a cooling source remote from the refrigeration unit that provides a cooling relationship with a condenser for providing optimum condensing and efficiency of the evaporators in cooling the associated product cooling zones.
• In another embodiment, the invention provides a modular refrigeration system including at least two refrigerated fixtures having first closely adjacent locations in a shopping area, at least one evaporator coil for cooling the refrigerated fixtures to maintain products therein within a predetermined temperature range, a linear compressor having a second location in close proximity to the refrigerated fixtures, and a condenser connected together with the linear compressor and the evaporator coils to form a closed loop refrigeration circuit. The modular refrigeration system also includes a heat exchange device located remote from the shopping area for transferring heat to an exterior atmosphere, and a closed heat transfer loop extending between the closed loop refrigeration circuit and the remote environment and interconnecting the heat exchange device and the condenser in continuous communication to transfer heat from the condenser to the heat exchange device.
• In still another embodiment, the invention provides a commercial refrigeration network including a first modular refrigeration system unit in close strategic proximity to a first refrigerated product zone. The first modular refrigeration system unit includes a first refrigeration rack having first closed refrigeration circuit components including a linear compressor, high side receiver means and associated high side and low side refrigerant delivery, and suction means operatively connected to a first evaporator for cooling the first refrigerated zone. The first modular refrigeration system unit also includes a first condenser connected between the linear compressor and receiver means of the first closed refrigeration circuit. The commercial refrigeration network also includes at least one other modular refrigeration system unit in close strategic proximity to an associated other refrigerated product zone. The at least one other modular refrigeration system includes an other refrigeration rack having other closed refrigeration circuit components including a linear compressor, high side receiver means and associated high side and low side refrigerant delivery, and suction means operatively connected to an other evaporator for cooling the other refrigerated zone. The other modular refrigeration system unit also includes an other condenser connected between the linear compressor and receiver means of the other closed refrigeration circuit. Further, the commercial refrigeration network also includes a cooling source remote from the refrigeration unit that provides a cooling relationship with the first and other condensers for the respective first and other refrigeration system units.
• In a further embodiment, the invention provides a commercial refrigeration network including a first refrigeration merchandiser, at least one other refrigeration merchandiser, and a cooling source. The first refrigeration merchandiser includes at least one first surface at least partially defining a first environmental space adapted to accommodate a commodity, first closed refrigeration circuit components, and a first frame. The first closed refrigeration circuit components include a free-piston linear compressor, a condenser, an expansion device, and an evaporator in fluid communication wherein the evaporator is in thermal communication with the environmental space to influence the temperature of the environmental space. The first frame supports the at least one first surface, the linear compressor and the evaporator. The at least one other refrigeration merchandiser includes at least one other surface at least partially defining an other environmental space adapted to accommodate a commodity, other closed refrigeration circuit components, and an other frame. The other closed refrigeration circuit components include a free-piston linear compressor, a condenser, an expansion device, and an evaporator in fluid communication wherein the evaporator is in thermal communication with the environmental space to influence the temperature of the environmental space. The other frame supports the at least one other surface, the linear compressor and the evaporator. The cooling source remote from the refrigeration unit provides a cooling relationship with the first and other condensers for the respective first and other refrigeration system units.
• Other aspects and advantages of the invention will become apparent by consideration of the detailed description, claims and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a block diagram illustrating a modular commercial refrigeration network embodying the invention.
• FIG. 2 is a schematic flow diagram of a modular refrigeration system unit and coolant circulating system.
• FIG. 3 is a schematic flow diagram of a refrigeration system unit and coolant circulating system located remotely from the respective refrigeration loads.
• FIG. 4 is a schematic flow diagram of a modular refrigeration system unit with an air cooled condenser.
• FIG. 5 is a representative supermarket floor plan illustrating the strategic placement of dedicated modular refrigeration system units relative to the respective refrigeration loads and positioned remotely of the respective refrigeration loads.
• FIG. 6 is a sectional view of a dual opposing, free-piston linear compressor used in a refrigeration unit, which shows the compressor at an intake stroke.
• FIG. 7 is a sectional view of a dual opposing, free-piston linear compressor used in a refrigeration unit, which shows the compressor at neutral.
• FIG. 8 is a sectional view of a dual opposing, free-piston linear compressor used in a refrigeration unit, which shows the compressor at a compression stroke.
• FIG. 9 is an enlarged supermarket floor plan illustrating a department with a dedicated modular refrigeration unit having multiple linear compressors.
• FIG. 9A is a top plan view of the refrigeration unit ofFIG. 9 illustrating a heat exchanger network with a cooling liquid source.
• FIG. 10 is an enlarged supermarket floor plan illustrating a department with merchandisers and a dedicated refrigeration unit having multiple linear compressors located remotely from the merchandisers.
• FIG. 11 is a diagrammatic perspective view showing an open front refrigerated merchandiser lineup and associated vertical modular refrigeration unit.
• FIG. 12 is another diagrammatic perspective view showing a lineup of reach-in merchandisers strategically incorporating a vertical modular refrigeration unit.
• FIG. 13 is a plan view of a lineup of wide island cases showing a linear compressor arrangement in the associated modular refrigeration unit.
• FIG. 14 is a plan view of a lineup of wide island cases with an associated refrigeration unit including multiple linear compressors located remotely of the wide island cases.
• FIG. 15 is a diagrammatic side elevational view illustrating a modular refrigeration rack for a refrigeration unit with multiple linear compressors.
• FIG. 15A is a diagrammatic plan view of the modular refrigeration rack ofFIG. 15.
• FIG. 16 is a perspective view of two refrigeration merchandisers and further showing elements of the refrigeration cycle of the merchandisers.
• Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
• For purposes of disclosure, the term “high side” is used herein in a conventional refrigeration sense to mean a portion of a system from the compressor discharge to the evaporator expansion valves, and the term “low side” means the portion of the system from the expansion valves to the compressor suction. Also, “low temperature” as used herein shall have reference to evaporator temperatures in the range of about −35° F. to about −5° F., or the associated product temperatures in the range of about −20° F. to about 0° F. Further, “normal temperature” as used herein means evaporator temperatures in the range of about 15° F. to about 40° F., or the associated non-frozen product temperatures in the range of about 25° F. to about 50° F. “Medium temperature” is also used interchangeably for “normal temperature” in the refrigeration industry.
DETAILED DESCRIPTION
• FIG. 1 illustrates an inventivecommercial refrigeration network10 diagrammatically. Thecommercial refrigeration network10 includes a plurality of modular refrigeration system units14 constructed and arranged for placement in strategic proximity to corresponding product cooling zones within a commercial space18 (e.g., a foodstore, supermarket, etc.). The location of the refrigeration units14 may be within or remote from acustomer shopping area22 of thecommercial space18. InFIG. 1, twomodular refrigeration units14A and14B are shown within theshopping area22, and onemodular refrigeration unit14C is shown outside of theshopping area22. Each refrigeration system unit14, or merchandiser, includes at least one linear compressor22 (shown inFIG. 2) and is sized to efficiently maintain its associated discrete cooling zone at optimum refrigeration temperatures. Each of the cooling zones comprises one or more of the store coolers, freezers, preparation rooms or display merchandisers. A cooling zone is typically an area, department, or lineup of merchandising fixtures operating at substantially the same temperature.
• Therefrigeration network10 includes acoolant circulating system30 constructed and arranged to circulate a cooling fluid or coolant from aremote source34 to a respective refrigeration unit condenser/heat exchanger38. The circulation of a controlled coolant in a heat exchange relationship with the unit condensers provides optimum condensing and refrigeration efficiency of the evaporators in cooling their respective product zones. Thecoolant system30 derives a cooling liquid, such as chemically treated water or a glycol solution, from one ormore sources34 and circulates the cooling liquid by at least onepump42 through a distribution arrangement. In the illustrated embodiment, the distribution arrangement includes adistribution manifold46 and branch coolant delivery lines orconduits50 to the condenser/heat exchanger34 of each modular unit14. For example, and as shown inFIGS. 2, 3, and16, a secondary fluid (e.g., a liquid) provided by the fluid-input line50, or conduits, cools thecondenser38. At least twoalternate cooling sources34A,34B are illustrated as an arrangement to assure a back-up condenser cooling system.Branch return conduits54, or a fluid-output, and a return manifold58 carry away the coolant fluid with the exchanged heat of rejection from the respectiverefrigeration unit condensers38 for dissipation externally of theshopping area22.
• Thecoolant sources34A,34B,34C,34D may be a single fluid cooling apparatus, such as a closed or open loop roof top cooling tower, a ground source water supply, a dedicated normal temperature refrigeration system, a chiller system or recirculating water source, or a combination of such alternate fluid cooling sources to assure a continuous supply of coolant at a substantially constant temperature, as will be discussed below. In an embodiment including multiple modular refrigeration units14, the refrigeration units14 derive their respective condenser cooling from a commonliquid cooling source34 remote from the modular refrigeration units14 in theshopping area22. In one embodiment, the heat exchanger is of the plate-to-plate type for optimal heat transfer of the heat of rejection transferred from the product zone through theunit condensers38 to the coolant, which then carries the cumulative heat load in a heated coolant return mode for dissipation externally of theshopping area22. It will be readily apparent to those skilled in the art that the heat of rejection and the heat of compression from the linear compressors may be utilized for seasonal heating of the supermarket.
• As will be discussed further below, the fluid can also be used to cool other components of the refrigeration unit14. In other embodiments, the merchandiser14 includes a fan if thecondenser38 is air-cooled.
• The modular nature of the refrigeration units14 utilizes three basic variable forms of the refrigeration unit14: a vertical compressor configuration, such as14C (shown inFIGS. 1, 11,12); a horizontal compressor configuration, such as14B (shown inFIGS. 1, 2,9,13,15); and a combination or mixed horizontal and vertical compressor configuration, such as14A (shown inFIGS. 1, 12,16).
• During a refrigeration cycle, thelinear compressor26 compresses a refrigerant, resulting in the refrigerant increasing in temperature and pressure. The compressed refrigerant is sent out of thelinear compressor26 as a high-temperature, high-pressure heated gas. The refrigerant travels to a condenser38 (shown inFIG. 2). Thecondenser38 changes the refrigerant from a high-temperature gas to a warm-temperature gas/liquid, which maintain the associated discrete cooling zones at an optimum refrigeration temperature. As discussed above, air and/or a liquid are used to help thecondenser38 with this transformation.
• FIG. 2 is a schematic flow diagram of a modular refrigeration unit14 andcoolant circulating system30. InFIG. 2, each of the modular refrigeration units14 includes arefrigeration rack62 constructed and arranged to mount and support the operative components of aclosed refrigeration circuit66. Theclosed refrigeration circuit66 is dedicated to refrigeration load requirements of its associated discreteproduct cooling zone68. In the illustrated embodiment, therefrigeration rack62 includes fourlinear compressors26 connected in parallel. In further embodiments, at least one and up to tenlinear compressors26 may be included in the refrigeration unit14 and supported by therefrigeration rack62. Thelinear compressors26 are connected by adischarge header70 to a divertingvalve74. The divertingvalve74 selectively connects thedischarge header70 to a heat recovery means, such as a heat reclaimcoil78 or a hot water exchanger (not shown), or directly to thesystem condenser38 located on therefrigeration rack62. In the illustrated embodiment, aliquid receiver82 is connected to thecondenser38 to receive the condensate outflow from thecondenser38.
• The high side of therefrigeration circuit66 is connected byliquid lines86 toevaporative expansion valves90 at each evaporator94 associated with a discreteproduct cooling zone68 to be cooled. On the low side, the refrigerant expands and vaporizes in themerchandiser evaporators94 removing heat from theproduct zone68 to maintain the preselected desired cooling. The outlets of theevaporators68 connect to a common suction header ormanifold98. Thesuction manifold98 connects to the suction side of thecompressors26 to complete therefrigeration circuit66. It will be readily apparent to those skilled in the art that individual modular refrigeration units14 may generally include other system components, such as defrost system means, system performance sensing and operating control panel, microprocessor apparatus, alarm systems and the like.
• FIG. 2 illustrates a unit heat reclaimcoil78 as part of theclosed refrigeration circuit66 of the refrigeration unit14. Such a heat reclaimcoil78 is generally housed in a conventional store air handler (not shown) for seasonal air conditioning and environmental heating of the store, but may be located remotely as a water heating unit (not shown). Due to the modularity of the refrigeration units14 and their proximate location to their respective cooled product zones, it is contemplated that unit heat reclaim coils78 may be strategically located under selected merchandisers or the like for environmental shopping arena heating. It will be readily apparent that a heat reclaimcoil78 is typically designed to function as a pre-condenser that removes heat from the compressed vaporous refrigerant on the high side upstream of the system condenser. The heat reclaimcoil78 does not reduce the refrigerant vapor to its saturated condensing temperature, because this is the final function of thecondenser38 at the unit heat exchanger.
• The use oflinear compressors26 in the refrigeration units14 provides for oil-free operation of the refrigeration system and gives performance and cost advantages over existing systems.Linear compressors26 used in the refrigeration units14 eliminate the need for oil management components (such as oil separators, oil controls, oil safety devices, etc) within the refrigeration system. Heat transfer within the refrigeration system is improved due to the absence of an oil film on evaporator and condenser surfaces. Further, installation costs are lower due to the elimination of the need for suction traps. The use oflinear compressors26 in the refrigeration units14 also provides for continuously variable capacity of the refrigeration loads from about 30% to 100% (discussed below with respect toFIGS. 6-8), as compared to existing systems utilizing scroll compressors.
• In the embodiment illustrated inFIG. 2, the modular refrigeration unit14 is strategically placed in thecommercial space18 in close proximity to thededicated cooling zone68 of an associated merchandiser department or case lineup. In another embodiment illustrated inFIG. 3, the components of theclosed refrigeration circuit66 are located remotely of thededicated cooling zone68, such as in a service area102 (shown inFIG. 5) of thecommercial space18. In some embodiments, the closed refrigeration circuit components, including thelinear compressors26, are not arranged on a refrigeration rack and instead are positioned separately to form theclosed refrigeration circuit66.
• In another embodiment illustrated inFIG. 4, the modular refrigeration unit14 includes an air cooledcondenser38 located remotely of therefrigeration rack62, for example on a roof of thecommercial space18. Afan100 mounted to or within thecondenser38 provides cooling to the refrigerant passing through the condenser. An air cooled condenser is an alternative cooling means from thecoolant circulating system30 shown inFIGS. 2 and 3. In further embodiments, the air cooledcondenser38 may be located remotely from thecommercial space18 or in theservice area102 of thecommercial space38.
• FIG. 5 is a representative supermarket floor plan illustrating the strategic placement of dedicated modular refrigeration system units14 relative to the respective refrigeration loads, as well as refrigeration units14 located remotely from the respective refrigeration loads in aservice area102 of thecommercial space18. In the embodiment illustrated inFIG. 5,refrigeration unit14A is a medium temperature system servicing theproduce department merchandisers68A operating at temperatures in the range of about 45° F. to about 50° F. (see alsoFIG. 9).Refrigeration unit14B is a low temperature system dedicated to maintain ice cream product temperatures of about −20° F. in twin island “coffin”type merchandisers68B in theshopping area22. Although therefrigeration unit14B is located in theservice area102, in further embodiments it may be located proximate themerchandisers68B (see alsoFIG. 13).Refrigeration unit14C is a low temperature system for a dual back-to-back lineup of frozen food reach-in merchandisers68C within the shopping area22 (see alsoFIG. 11).Refrigeration unit14D is a low temperature system dedicated to maintain frozen meat products in a meat freezer (coolingzone68D) located in theservice area102 outside of theshopping area22.Refrigeration unit14E is a medium temperature system located in theservice area102, but immediately adjacent to its discrete service load ofmulti-deck meat merchandisers68E in theshopping area22.Refrigeration unit14F is a medium temperature system for a lineup of non-frozen reach-inproduct fixtures68F in theshopping area22.Refrigeration unit14G is a medium temperature system also located in theservice area102, but constructed and arranged to service both a deli walk-in cooler68G1 in theservice area102 and a deli merchandiser lineup68G2 in theshopping area22.Refrigeration unit14H is a medium temperature system for servicing a line ofmulti-deck produce merchandisers68H. In the illustrated embodiment, therefrigeration unit14H is located in theservice area102, however, in another embodiment therefrigeration unit14H is located proximate themerchandisers68H (see alsoFIG. 11). Refrigeration unit14I is a low temperature system dedicated to an ice cream walk-in freezer68I in theservice area102. Finally,refrigeration unit14J is a medium temperature system associated with a dairy department lineup ofmulti-deck merchandisers68J. In the illustrated embodiment,refrigeration unit14J is located in theservice area102, however, in another embodiment therefrigeration unit14J is located proximate themerchandisers68J.
• It will be readily apparent to those skilled in the art that a typical supermarket layout may also include a refrigerated floral merchandiser, an in-store bakery with coolers and retarder units, a seafood department and other non-refrigerated departments, dry goods shelving, customer checkout area and the like. As illustrated inFIG. 5, the conventional compressor machine room of existing supermarkets is eliminated in favor of themodular refrigeration units14A-14J strategically located in and around theshopping area22 and in theservice area102 of thecommercial space18. The refrigeration units14 are specifically dedicated to discrete refrigeration loads. Those refrigeration units14 located in close proximity to an associated group of storage or display merchandising zones operate at the same temperature and form the discrete load. In further embodiments, theservice area102 of thecommercial space18 may have a separate compressor machine room (not shown) for housing thelinear compressors26. However, the use oflinear compressors26 results in virtually no vibration, therefore, the need for a separate space to acoustically isolate the compressors is not necessary.
• As described herein, the refrigeration systems, refrigeration units, and merchandisers include at least onelinear compressor26. It is envisioned that, in some embodiments, the linear compressor is a free-piston linear compressor, and in at least on envisioned embodiment, the free-piston linear compressor is a dual-opposing, free-piston linear compressor. A dual-opposing, free-piston linear compressor is obtainable from Sunpower, Inc. (Athens, Ohio, USA). Another example of a dual-opposing, free-piston linear compressor is disclosed in U.S. Pat. No. 6,641,377, issued Nov. 4, 2003, the content of which is incorporated herein by reference.
• The free-piston linear compressor has some basic differences over conventional rotary compressors. The free-piston device is driven by a linear motor in a resonant fashion (like a spring-mass damper) as opposed to being driven by a rotary motor and mechanical linkage. One advantage with the linear motor is that the side loads are small, which greatly reduces friction and allows use of simple gas bearings or low-viscosity oil bearings. In addition, since friction has been greatly reduced, the mechanical efficiency of the device is greater, internal heat generation is lower, and acoustic noise is reduced. Additionally, inherent variable piston stroke allows for efficient capacity modulation over a wide range. For example, linear compressors have continuously variable capacity from about 30% to 100% by adjusting piston stroke. In constructions having dual-opposing pistons, the pistons vibrate against each other (i.e., provide a mirrored system) to virtually cancel all vibration. This reduces the acoustic noise of the linear compressor even further than a single piston linear compressor.
• FIGS. 6, 7, and8 show three sectional views of a dual-opposinglinear compressor110 capable of being used with the modular refrigeration systems, refrigeration units and merchandisers described above.FIG. 6 shows thecompressor110 at an intake stroke,FIG. 7 shows thecompressor110 at neutral, andFIG. 8 shows thecompressor110 at a compression stroke. As shown inFIGS. 6-8, the dual-opposinglinear compressor110 includes ahousing114 supporting amain body block118. Inner andouter laminations122 and126 are secured to themain body block118 and coils130 are wound on theouter laminations126, thereby forming stators. The stators, when energized, interact with magnet rings134 mounted onouter cylinders138. Theouter cylinders138 are fastened topistons142, which are secured tosprings146. The interaction between the magnet rings134 and the energized stators results in theouter cylinders138 moving thepistons142 linearly along an axis ofreciprocation150.
• When thepistons142 are at the intake stroke, refrigerant is allowed to flow from asuction port154 throughchannels158 into a compression space162 (best shown inFIG. 6). When moving from the intake stroke to the compression stroke, valves166 (best shown inFIG. 7) close the channels, and the refrigerant is compressed out throughdischarge valve170 and discharge port174 (best shown inFIG. 8). The linear motor allows for variable compression (e.g., from approximately 30% to 100%) by thepistons142, and therefore, thelinear compressor110 provides variable capacity control. In other words, the linear motors can cause thepistons142 to move a small stroke for a first volume, or to move a larger stroke for a second, larger volume. Thelinear compressors110 provide a variable refrigeration capacity (e.g., by varying piston stroke) balanced to the refrigeration loads imposed by the associatedproduct cooling zones68. Accordingly, the refrigeration units14 allow for variable loads, decrease compressor cycling, and reduce temperature swings.
• In some embodiments, thelinear compressor110 includes a jacket178 (shown in phantom) enclosing at least a portion of thehousing114. Thejacket178 includes a fluid-input port182 and a fluid-output portion186, and provides a plenum190 containing a cooling fluid, thereby providing a fluid-cooled compressor. Other arrangements for cooling the compressor with a fluid are possible.
• An example of a compressor controller for use with the dual-opposing, free-piston linear compressor shown inFIGS. 6-8 is disclosed in U.S. Pat. No. 6,536,326, issued Mar. 25, 2003, the content of which is incorporated herein by reference. It is also possible for the coolant fluid to be used for cooling a controller192 (shown inFIG. 11). Similar to the linear compressor, a jacket having input and output ports can be used to surround a housing of the controller.
• An example ofrefrigeration unit14A and its associated refrigeratedzone68A is illustrated inFIGS. 9 and 9A. The cooling zone illustrated is a medium temperature produce section ordepartment194 of a supermarket. The illustratedcooling zone194 includes two refrigerated produce tables194A, one unrefrigerated produce table194B (used for products not requiring refrigeration), and one or more lineups of multi-deck orgondola produce merchandisers194C. Therefrigeration unit14A may be concealed under one of the refrigerated tables194A, in the base of the unrefrigerated produce table194B, or in amerchandiser lineup194C. Therefrigeration unit14A may be accessed by removing a front panel of the merchandiser, or by constructing and arranging a table top of the merchandiser to be hinged for vertical lifting movement or for horizontal side movement thereon. In the illustrated embodiment, therefrigeration rack62 is constructed and arranged to support fourlinear compressors26 in a combination arrangement of two pairs of horizontally disposed compressors in side-by-side relationship. The linear compressors are connected in parallel and may be operated individually, cyclically or variably to keep the merchandiser temperatures constant.FIG. 9A shows that thecondenser38 of themodular unit14A is part of aheat exchanger198 containing a coolant loop having coolcoolant delivery mode50 and a warmcoolant return mode54.
• FIG. 10 is an alternate configuration of thecooling zone194 shown inFIG. 9.FIG. 10 illustrates a refrigeration system having refrigeration components located remotely of the associated refrigeratedzone68A. The refrigeration components may be located on arefrigeration rack62 or positioned independently to form theclosed refrigeration circuit66. Referring toFIGS. 9 and 10, adischarge conduit202 connects the compressor head manifold70 (i.e., discharge header) to theunit condenser38 on therefrigeration rack62. Thecondenser38 connects through the system receiver-accumulator82 (shown inFIG. 2) to theliquid line conduits86 that extend in short runs from therefrigeration unit14A beneath the floor to theevaporators94 in themerchandisers194. Asuction conduit206 returns the vaporized refrigerant liquid to thecompressors26. In the illustrated embodiment, acoolant delivery line50 from the remote cooling liquid source34 (shown inFIG. 1) is piped beneath the floor or overhead to therefrigeration rack62 for removing the heat of rejection and compression from theunit condenser38 in theheat exchanger198. Further, acoolant return line54 is provided to expel this heat to a location exterior of the supermarket. In a further embodiment of therefrigeration unit14A shown inFIGS. 9 and 10, the condenser is air cooled and located remotely of therefrigeration unit14A.
• Additional configurations of thelinear compressors26 accommodated by the modular refrigeration racks62 and their associated discrete refrigeration loads are shown inFIGS. 11-14. In each embodiment, all of the closed refrigeration circuit components are rack mounted except for the merchandiser68 orother zone evaporators94 and associated refrigerant control and sensing means. Examples of other equipment not mounted on the refrigeration rack includeexpansion valves90 and defrost control valves (not shown), as well as connecting discharge and suction lines between the evaporators and the refrigeration system racks.
• InFIG. 11, the modular refrigeration unit14 utilizes a vertical linear compressor unit that is positioned behind ashelving unit210. Theshelving unit210 is arranged to cover one side of the modular refrigeration unit14 when positioned at the end of a merchandiser lineup, such as the open frontmulti-deck merchandisers214 shown inFIG. 11.FIG. 12 illustrates lineups of reach-in merchandisers, such asmerchandiser68F, in which the modular refrigeration units and refrigeration racks are interposed into the middle of the lineups. InFIG. 12, therefrigeration unit14F includes a vertical stack oflinear compressors26.
• FIG. 13 illustrates another configuration of a horizontal linear compressor unit centrally located between parallel rows or twinisland coffin merchandisers68B of the type used for ice cream or other frozen products. The threelinear compressors26 are arranged on a horizontal line in themodular refrigeration unit14B and at least one exterior side of therefrigeration rack62 has aremovable panel218 that can be replaced after service. In the embodiment illustrated inFIG. 14, therefrigeration unit14B and therefrigeration rack62 are positioned remotely from the parallel rows or twinisland coffin merchandisers68B, oftentimes in a service area102 (shown inFIG. 5) of thecommercial space18.
• The location of the modular refrigeration units14, whether in theshopping area22 or in theservice area102 of thecommercial space18, are in close proximity to the associated refrigeration loads serviced by the respective units. Such placement greatly reduces the amount of refrigerant needed and the length of piping needed to carry the refrigerant to all the product merchandisers. The placement of the refrigeration units14 in theshopping area22 is commercially feasible only if the acoustic noise from the compressors is substantially eliminated or reduced to acceptable decibel levels. As discussed above, the use of linear compressors in the refrigeration units reduces the acoustic noise of the refrigeration unit and virtually cancels all vibration of the unit, as compared to compressors used in prior art systems.
• The modularity of the refrigeration racks62 for forming variant refrigeration unit arrangements is described with respect toFIGS. 15 and 15A. In the illustrated embodiment, therefrigeration rack62, for a horizontal linear compressor unit, includes a series ofsimilar frame modules220. Eachframe module220 includes a main frame having lower or first level horizontalstructural members224 forming a rectangular base andvertical struts228, or stanchions, located at the corners of thebase224.FIGS. 15 and 15A illustrate a four linear compressor unit with threeframe modules220 joined together. The two leftward modules also include upper or second level horizontalstructural member232 secured to thevertical stanchions228 in spaced relation above thelower base level224. Eachframe module220 is provided with a horizontally extending metal support or mounting plate236 that is preformed to receive and secure specific components of the closed refrigeration system. In the illustrated embodiment, theleftward mounting plates236A are each constructed and arranged to mount twolinear compressors26. It will be readily apparent that the condenser/heat exchanger38 and thereceiver82 are also accommodated by the modular refrigeration rack arrangement. Therightward unit236B is designed to mount acontrol panel240 for operating the associated refrigeration system of the modular refrigeration unit.
• It will also be readily apparent to those skilled in the art that the samebase frame module220, lowerlevel base frame224,vertical struts228,second level frame232, and mounting plate236 may be used to form a vertically arranged refrigeration rack or a combination refrigeration rack. The embodiment shown and described with respect toFIGS. 15 and 15A is illustrative only. The refrigeration rack may assume other configurations, such as a vertical linear compressor arrangement in which singlelinear compressors26 are stacked one above the other in a tier that affords a minimum floor space footprint and excellent accessibility for service.
• The modular refrigeration unit14 includes a single electrical junction to the refrigeration rack that permits the connection of all system components as well as local wiring control over the ancillary merchandiser electrical equipment (e.g., lighting, fans, antiswear heaters) for wiring from the same location. Only a single power circuit is required to extend from a remote power source (not shown) to the unit junction box usually associated with thecontrol panel240. In the illustrated embodiment, the junction box is connected to the control panel that contains a remotely activated contactor and circuit breaker system for providing distributed electrical power via buss arrangement to the electrical components in the system.
• In one embodiment, each of the modular refrigeration units is monitored and controlled by a personal computer linked to a microprocessor within thecontrol panel240. The control system is conventional, except that the linear compressors are located around the commercial space, and are supplemented by individual control systems (i.e., microprocessors) associated with each rack. Interrogation of individual units to diagnose problems and override of the general control functions for purposes of testing and repair is accomplished at the specific refrigeration units. To reduce duplication of components such as visual system readouts on each control panel, it is envisioned that a hand-held monitor would be used to plug into the microprocessor and provide a visual readout of its settings and conditions.
• The modularity of the refrigeration units14 and the refrigeration racks62 reduces the time and cost of installing the refrigeration system network and simplifies service, as compared to conventional back room refrigeration systems. Further, since the alternate configurations of the refrigeration units and racks are pre-designed, less field assembly of conduit joints are required. The flexibility in the modular refrigeration units permits the dedicated units to be located unobtrusively within a public area of a commercial space, such as a supermarket, in such a way as to blend with the closely adjacent configurations of refrigerated product storage coolers and display merchandisers having the associated cooling zones.
• FIG. 16 shows a self-containedrefrigeration unit250, or merchandiser. Therefrigeration unit250 is shown as an open-unit display merchandiser having asingle display fixture254. However, other types of merchandisers (e.g., a glass-door display merchandiser, a vending machine, a dispenser, etc.) can embody the invention. Also, it is envisioned that themerchandiser250 can include more than one display fixture (e.g., is a combination merchandiser). As used herein, the term “self-contained refrigeration unit” means a refrigeration unit where the frame of the unit supports thelinear compressors26, thecondenser38, theexpansion valve90, and theevaporator94.
• With reference toFIG. 16, themerchandiser250 includes aframe258 supporting thedisplay fixture254 and the components providing the refrigeration cycle (discussed below). As used herein, the term “frame” is broadly defined as something composed of parts fitted together and united. Theframe258 includes the housing of the unit, the one or more components of the refrigeration cycle, and/or the display fixture. Alternatively, theframe254 provides the foundation for the housing, the one or more components of the refrigeration cycle, and/or the display fixture. Thedisplay fixture254 comprises a cabinet, case, container or similar receptacle adapted to accommodate a commodity. Thefixture254 includes at least onesurface262 that at least partially defines an environmental space. For a “glass-door” display merchandiser, at least one of the surfaces defining the environmental space is partially defined by a translucent material.
• It should be noted that some merchandisers do not include a display fixture, however, the refrigeration unit still includes at least one surface at least partially defining an environmental space. Also therefrigeration unit250 can include multiple environmental spaces. As used herein, the term “environmental space” is a three-dimensional space (defined at least in part by the at least one surface) where the environment is controlled by the refrigeration unit. For example, therefrigeration unit250 ofFIG. 16 consists of twoenvironmental spaces266 and270, where the temperatures of the environmental spaces are controlled by the components of the refrigeration cycle. Other characteristics (e.g., humidity) of theenvironmental spaces266 and270 can be controlled.
• As shown inFIG. 16, the components forming the refrigeration cycle comprises thelinear compressor26, thecondenser38, the expansion device90 (also typically referred to as the expansion valve), and theevaporator94, all of which are in fluid communication. Of course, in further embodiments, the refrigeration cycle can include other components, such as thereceiver82 or a filter (not shown).
• The refrigeration unit includes thecontroller192 that controls the refrigeration unit. Thecontroller192 includes one or more temperature sensors and/or one or more pressure sensors (only onesensor274 is shown) coupled to the refrigeration unit. The controller also includes a user-input device. Thecontroller192 receives refrigeration unit input information (i.e., signals or data) from the sensor(s)274, receives user input (e.g., temperature settings) from the user input device, processes the inputs, and provides one or more outputs to control the refrigeration unit (e.g., to control the compressor, control the expansion device, control a defrost system, etc.). In further embodiments, thecontroller192 is used with other refrigeration units or merchandisers and may be located in thecontrol panel240 of such units.
• For the refrigeration unit shown, thecontroller192 includes the compressor controller. However, therefrigeration unit controller192 can be separated into multiple controllers (e.g., a controller for overall control and a compressor controller), which is typically referred to as a distributed control system. An example of a distributed control system is disclosed in U.S. Pat. No. 6,647,735, issued Nov. 18, 2003, the content of which is incorporated herein by reference.
• In one embodiment, thecontroller192 includes one or more programmable devices (e.g., one or more microprocessors, one or more microcontrollers, etc.) and a memory. The memory, which can include multiple memory devices, includes program storage memory and data storage memory. The one or more programmable devices receive instructions, receive information (either directly or indirectly) from the devices in communication with the programmable devices, execute the instructions, process the information, and communicate outputs to the attached devices.
• The user-input device is shown inFIG. 16 as auser interface278. The user-input device can be as simple as a thermostat dial. Other user-input devices include push-buttons, switches, keypads, a touch screen, etc. Theuser interface278 also includes a user-output device (e.g., a LCD display, LEDs, etc.). In another embodiment, theuser interface278 includes connections for communication to other interfaces or computers or is located in thecontrol panel240 of the refrigeration unit.
• It is envisioned that thecontroller192 can use at least one of a sensed pressure and a sensed temperature to control the linear compressor, the expansion device, and/or the fans. By controlling these components, thecontroller192 thereby controls the temperature of the environmental space(s) of the refrigeration unit. For example, thecontroller192 can include a temperature sensor that senses discharge air temperature. If the discharge air temperature is outside of a predetermined temperature range (e.g., set by an operator), thecontroller192 can modulate or change the volume of the compressor (e.g., increase or decrease the stroke of the pistons of the compressor). How thecontroller192 changes the compressor volume can be based on empirical test data. Other methods known to those skilled in the art for controlling the compressor are possible. Other parameters used by thecontroller192 for controlling the compressor can include suction temperature, suction pressure, discharge pressure, evaporator air exit temperature, evaporator surface temperature, evaporator pressure, the temperature difference between discharge and return air temperature, product zone temperature, product simulator temperature, and similar parameters.
• Various other features and advantages of the invention are set forth in the following claims.

Claims (46)

1. A modular commercial refrigeration unit constructed and arranged for placement in strategic proximity to a plurality of associated product cooling zones within a shopping area, the modular refrigeration unit comprising:

a refrigeration rack proximate to a shopping area and configured to accommodate maximum refrigeration loads of the associated product cooling zones and having an optimum footprint,

wherein the refrigeration rack is constructed to support components of a closed refrigeration circuit including associated high side and low side refrigerant delivery and suction means extending from the rack and being operatively connected to a plurality of evaporators for cooling the associated product cooling zones;

a linear compressor; and

a cooling source remote from the refrigeration unit provides a cooling relationship with a condenser for providing optimum condensing and efficiency of the evaporators in cooling the associated product cooling zones.

2. The modular refrigeration unit ofclaim 1 wherein the closed refrigeration circuit includes a plurality of linear compressors.

3. The modular refrigeration unit ofclaim 2 wherein the linear compressors are connected in parallel.

4. The modular refrigeration unit ofclaim 1 wherein the linear compressor provides a variable refrigeration capacity balanced to the refrigeration loads imposed by the associated product cooling zones.

5. The modular refrigeration unit ofclaim 4 wherein the variable refrigeration capacity is in the range of about 30% and 100%.

6. The modular refrigeration unit ofclaim 1 wherein the linear compressor comprises a free-piston linear compressor including dual-opposing pistons.

7. The modular refrigeration unit ofclaim 1, and further comprising a controller to control the operation of the linear compressor wherein the controller comprises a sensor configured to sense a parameter representative of an operating condition associated with the modular refrigeration unit, and wherein the controller is operable to control the linear compressor based at least in part on the sensed parameter.

8. The modular refrigeration unit ofclaim 7 wherein the linear compressor comprises a free-piston linear compressor comprising dual-opposing pistons, and wherein the controller is operable to control the linear compressor by being further operable to control the stroke of the pistons for varying the effective displaced volume of refrigerant based at least in part on the sensed parameter.

9. The modular refrigeration unit ofclaim 1 wherein the linear compressor is located remote from the shopping area.

10. The modular refrigeration unit ofclaim 1 wherein the linear compressor is mounted on the refrigeration rack.

11. The modular refrigeration unit ofclaim 1, and further comprising a condenser connected between the linear compressor and receiver means of the refrigeration circuit.

12. The modular refrigeration unit ofclaim 11 wherein the condenser is mounted on the refrigeration rack.

13. The modular refrigeration unit ofclaim 11 wherein the condenser is air cooled.

14. The modular refrigeration unit ofclaim 1 wherein the cooling source provides a heat exchange relationship with the condenser for providing optimum condensing and efficiency of the evaporators in cooling the associated product cooling zones.

15. A modular refrigeration system comprising:

at least two refrigerated fixtures having first closely adjacent locations in a shopping area;

at least one evaporator coil for cooling the refrigerated fixtures to maintain products therein within a predetermined temperature range;

a linear compressor having a second location in close proximity to the refrigerated fixtures;

a condenser connected together with the linear compressor and the evaporator coils to form a closed loop refrigeration circuit;

a heat exchange device located remote from the shopping area for transferring heat to an exterior atmosphere; and

a closed heat transfer loop extending between the closed loop refrigeration circuit and the remote environment and interconnecting the heat exchange device and the condenser in continuous communication to transfer heat from the condenser to the heat exchange device.

16. The refrigeration system ofclaim 15 wherein the second location is in the shopping area closely adjacent to the refrigerated fixtures.

17. The refrigeration system ofclaim 15 wherein the second location is remote from the shopping area.

18. The refrigeration system ofclaim 15 wherein the closed loop refrigeration circuit includes a plurality of linear compressors.

19. The refrigeration system ofclaim 18 wherein the linear compressors are connected in parallel.

20. The refrigeration system ofclaim 15 wherein the linear compressor provides a variable refrigeration capacity balanced to the refrigeration loads imposed by the associated refrigerated fixtures.

21. The refrigeration system ofclaim 20 wherein the variable refrigeration capacity is in the range of about 30% and 100%.

22. The refrigeration system ofclaim 20 wherein the linear compressor comprises a free-piston linear compressor including dual-opposing pistons.

23. The refrigeration system ofclaim 22 wherein the variable refrigeration capacity is controlled by varying stroke of the pistons.

24. The refrigeration system ofclaim 15, and further comprising a controller coupled to the linear compressor, the controller comprising a sensor configured to sense a parameter representative of an operating condition associated with the refrigerated fixtures, and wherein the controller is operable to control the linear compressor based at least in part on the sensed parameter.

25. A commercial refrigeration network comprising:

a first modular refrigeration system unit in close strategic proximity to a first refrigerated product zone, the first modular refrigeration system unit including a first refrigeration rack comprising first closed refrigeration circuit components including a linear compressor, high side receiver means and associated high side and low side refrigerant delivery, and suction means operatively connected to a first evaporator for cooling the first refrigerated zone, and the first modular refrigeration system unit also including a first condenser connected between the linear compressor and receiver means of the first closed refrigeration circuit;

at least one other modular refrigeration system unit in close strategic proximity to an associated other refrigerated product zone, and including an other refrigeration rack comprising other closed refrigeration circuit components including a linear compressor, high side receiver means and associated high side and low side refrigerant delivery, and suction means operatively connected to an other evaporator for cooling the other refrigerated zone, and the other modular refrigeration system unit also including an other condenser connected between the linear compressor and receiver means of the other closed refrigeration circuit; and

a cooling source provides a cooling relationship with the first and other condensers for the respective first and other refrigeration system units.

26. The refrigeration network ofclaim 25 wherein the first and other refrigerated product zones are located within a shopping area at spaced locations therein, and the dedicated first and other refrigeration racks are closely associated with the respective product zones adjacent to their respective locations.

27. The refrigeration network ofclaim 25 wherein the refrigerated product zones comprise a plurality of merchandisers located in the shopping arena, the plurality of merchandisers comprising:

first merchandisers incorporating the first evaporator and associated first refrigerant control means and first refrigeration sensing means; and

other merchandisers incorporating the other evaporator and associated other refrigerant control means and other refrigeration sensing means.

28. The refrigeration network ofclaim 25 wherein at least one of the modular refrigeration system units includes a plurality of linear compressors.

29. The refrigeration network ofclaim 28 wherein the linear compressors are connected in parallel.

30. The refrigeration network ofclaim 25 wherein the linear compressors provide a variable refrigeration capacity balanced to the refrigeration loads imposed by the associated refrigerated zones.

31. The refrigeration network ofclaim 30 wherein the variable refrigeration capacity is in the range of about 30% and 100%.

32. The refrigeration network ofclaim 25 wherein each modular refrigeration system unit further comprises a controller coupled to the linear compressor, the controller comprising a sensor configured to sense a parameter representative of an operating condition associated with the modular refrigeration unit, and wherein the controller is operable to control the linear compressor based at least in part on the sensed parameter.

33. The refrigeration network ofclaim 32 wherein each linear compressor comprises a piston, and wherein the controller is operable to control the linear compressor by being further operable to control the stroke of the piston based at least in part on the sensed parameter.

34. The refrigeration network ofclaim 32 wherein each linear compressor comprises a free-piston linear compressor comprising dual-opposing pistons, and wherein the controller is operable to control the linear compressor by being further operable to control the stroke of the pistons for varying the effective displaced volume of refrigerant based at least in part on the sensed parameter.

35. The refrigeration network ofclaim 25 wherein the cooling source comprises a plurality of cooling sources, each cooling source mounted to a respective one of the first and other condensers.

36. The refrigeration network ofclaim 25 wherein the cooling source comprises a coolant circulating system having a plurality of heat exchanger circuits in heat exchange relationship with the respective first and other condensers for the respective first and other refrigeration system units, the coolant circulating system having at least one continuous cooling source for coolant in the circulating system.

37. A commercial refrigeration network comprising:

a first refrigeration merchandiser comprising at least one first surface at least partially defining a first environmental space adapted to accommodate a commodity, first closed refrigeration circuit components including a free-piston linear compressor, a condenser, an expansion device, and an evaporator in fluid communication wherein the evaporator is in thermal communication with the environmental space to influence the temperature of the environmental space, and a first frame supporting the at least one first surface, the linear compressor and the evaporator;

at least one other refrigeration merchandiser comprising at least one other surface at least partially defining an other environmental space adapted to accommodate a commodity, other closed refrigeration circuit components including a free-piston linear compressor, a condenser, an expansion device, and an evaporator in fluid communication wherein the evaporator is in thermal communication with the environmental space to influence the temperature of the environmental space, and an other frame supporting the at least one other surface, the linear compressor and the evaporator; and

a cooling source provides a cooling relationship with the first and other condensers for the respective first and other refrigeration system units.

38. The refrigeration network ofclaim 37 wherein the first frame also supports the condenser and the expansion device and the other frame also supports the condenser and the expansion device.

39. The refrigeration network ofclaim 37 wherein at least one of the refrigeration merchandisers includes a plurality of linear compressors.

40. The refrigeration network ofclaim 39 wherein the linear compressors are connected in parallel.

41. The refrigeration network ofclaim 37 wherein the linear compressor provides a variable refrigeration capacity balanced to refrigeration loads imposed by the refrigeration merchandiser.

42. The refrigeration network ofclaim 41 wherein the variable refrigeration capacity is in the range of about 30% to 100%.

43. The refrigeration network ofclaim 41 wherein the linear compressor comprises dual-opposing pistons.

44. The refrigeration network ofclaim 43 wherein the variable refrigeration capacity is controlled by varying stroke of the pistons.

45. The refrigeration network ofclaim 37 wherein the cooling source comprises a plurality of cooling sources, each cooling source mounted to a respective one of the first and other condensers wherein the first and other condensers are air cooled.

46. The refrigeration network ofclaim 37 wherein the cooling source comprises a coolant circulating system having a fluid input line and a fluid output line in fluid communication with the respective first and other condensers for the respective first and other refrigeration merchandisers, the coolant circulating system having at least one continuous cooling source for coolant in the circulating system.

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