REFRIGERATION SYSTEM HAVING HEAT PUMP AND MULTIPLE MODES OF OPERATION
The present invention provides a refrigeration system including a first refrigerant circuit including a first heat exchanger for transferring heat from refrigerant, a second refrigerant circuit including a second heat exchanger for transferring heat to refrigerant, and a third refrigerant circuit. The third refrigerant circuit includes a compressor, a condenser connected to the first refrigerant circuit such that heat exchange can occur between the refrigerants of the first and refrigerant circuits, an expansion device, and an evaporator connected to the second refrigerant circuit such that heat exchange can occur between the refrigerant of the second and third refrigerant circuits. The refrigerant can travel along the third refrigerant circuit in a common direction during operation in both heating and cooling modes. Refrigerant can be prevented from moving between first, second, and third refrigerant circuits during operation in heating and cooling modes.
The present application claims priority to U.S. Provisional Patent Application Ser. No. 60/933,713, filed Jun. 8, 2007, the entire contents of which is hereby incorporated by reference.
FIELD OF THE INVENTIONThe present invention relates to a refrigeration system and a method of manufacturing a refrigeration system, and more particularly to a refrigeration system having both an air heating or heat pump mode and an air conditioning or cooling mode.
SUMMARYIn principal, a CO2 heat pump system can be switched from a heat pump or heating mode (HP) to air conditioning or cooling (A/C) mode by changing the flow direction in the system cycle so that the A/C mode evaporator operates as a HP mode gas cooler, and the A/C mode gas cooler operates as an HP mode evaporator. However, there are some practical limitations to this method, which include, but are not limited to, the need for valves able to accommodate high pressure CO2, appropriately sized accumulators, and heat exchangers in such a system able to withstand higher system pressures for a fully-reversible system.
In accordance with one feature of the present invention, a refrigeration system is provided that can be operated in both HP and A/C modes without changing the general direction of refrigerant flow through the system. This is done by employing two secondary coolant loops, and adding additional heat exchangers. One desirable application for this system is the cabin heating and cooling required for truck idle-off. In some embodiments, CO2 can be used as a refrigerant in at least one refrigerant circuit.
In some embodiments, the invention provides a refrigeration system having both a heating mode for providing heat to a load space and a cooling mode for removing heat from the load space. The system can include a first refrigerant circuit including a first heat exchanger for transferring heat from refrigerant of the first refrigerant circuit to air, a second refrigerant circuit including a second heat exchanger for transferring heat from air to refrigerant of the second refrigerant circuit, and a third refrigerant circuit. The third refrigerant circuit can include a compressor for increasing pressure of refrigerant of the third refrigerant circuit, a condenser connected to the compressor for receiving refrigerant from the compressor and connected to the first refrigerant circuit such that heat exchange can occur between the refrigerant traveling through the first refrigerant circuit and the refrigerant traveling through the third refrigerant circuit, an expansion device for reducing the pressure of the refrigerant of the third refrigerant circuit, and an evaporator connected to the expansion device and connected to the second refrigerant circuit such that heat exchange can occur between the refrigerant traveling through the second refrigerant circuit and the refrigerant traveling through the third refrigerant circuit. The refrigerant can travel along the third refrigerant circuit in a common direction during operation in both the heating mode and the cooling mode. The refrigerant can be prevented from moving between the first refrigerant circuit, the second refrigerant circuit, and the third refrigerant circuit during operation in the heating and cooling modes.
In some embodiments, the present invention provides a refrigeration system having both a heating mode for providing heat to a load space and a cooling mode for removing heat from the load space. The refrigeration system can include a first refrigerant circuit extending between a compressor, an evaporator, an expansion device, and a condenser. The first refrigerant circuit can define a flow path for a refrigerant traveling in a direction along the refrigerant circuit during operation of the refrigeration system in the heating mode and the cooling mode. The refrigeration system can also include a second refrigerant circuit extending between the condenser and a heat exchanger, the second refrigerant circuit including a first refrigerant pump, and a third refrigerant circuit extending between the evaporator and the heat exchanger. The third refrigerant circuit can include a second refrigerant pump. The second refrigerant pump can be operational during operation in the heating mode and can be idle during operation in the cooling mode.
The present invention also provides a method of operating a refrigeration system. The method can include the acts of directing a refrigerant along a refrigerant circuit in a direction between a compressor, an evaporator, an expansion device, and a condenser during operation of the refrigeration system in a cooling mode, operating a first pump when the refrigeration system is operating in the cooling mode to circulate refrigerant through a heat exchanger, and transferring heat from a load space to the refrigerant in the refrigerant circuit when the refrigeration system is operating in the cooling mode. The method can also include the acts of stopping the first pump when the refrigeration system is operating in a heating mode, directing the refrigerant along the refrigerant circuit in the direction during operation of the refrigeration system in the heating mode, operating a second pump when the refrigeration system is operating in the heating mode to circulate refrigerant through the heat exchanger in heat exchange relation with the refrigerant of the refrigerant circuit, and transferring heat to the load space from the refrigerant in the refrigerant circuit when the refrigeration system is operating in the heating mode.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
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.
Also, it is to be understood that phraseology and terminology used herein with reference to device or element orientation (such as, for example, terms like “central,” “upper,” “lower,” “front,” “rear,” and the like) are only used to simplify description of the present invention, and do not alone indicate or imply that the device or element referred to must have a particular orientation. In addition, terms such as “first”, “second”, and third” are used herein for purposes of description and are not intended to indicate or imply relative importance or significance.
The refrigerant can then enter a second evaporator, which, in the illustrated embodiment of
As shown in
In the liquid-to-refrigerant evaporator 26, the refrigerant can evaporate, receiving heat energy from and thereby cooling down a coolant (e.g., glycol, water, R12, engine coolant, any organic refrigerant, R245fa, air, and the like) flowing through the liquid-to-refrigerant evaporator 26 from another secondary, low temperature coolant loop 28. It should be noted that the air-heated evaporator 24 can be placed either upstream or downstream of the liquid-heated evaporator 24 with respect to the flow of the refrigerant. The same can be said of the liquid-cooled gas cooler 18 with respect to the air-cooled gas cooler 14. However, it can be desirable to avoid excess heating and/or boiling of the slow moving or stagnant liquid in the liquid-cooled gas cooler 18 during operation of the refrigeration system 10 in the A/C mode.
After traveling through the evaporator 26, the refrigerant can reject heat to the high pressure refrigerant in the SLHX 20. An accumulator (not shown in
In addition to the liquid-refrigerant evaporator 26, the low temperature coolant loop 28 can include a pump 29 for moving liquid coolant through the liquid side of the evaporator 26. While heat from the coolant is transferred to the refrigerant in the evaporator 26, a heat exchanger cooler core 30, which can be mounted in an inside space 32, such as, for example, the cabin of a truck or another vehicle, can operate to transfer heat away from the low temperature coolant in the coolant loop 28. The cooler core 30 can be accompanied by an air mover 34, such as a fan or blower, and can cool down the air inside the space 32 and/or remove humidity from the air in the space 32. In some embodiments, if the air stream through or across the heat exchanger 30 is cooled below the dew point, a small amount of liquid coolant can be circulated through the hot coolant loop 19 to reheat the air entering the cabin (as shown by three dashed arrows).
In other embodiments, the waste heat source 42 and/or a different waste heat source 42 can also or alternatively provide heat to a liquid-to-liquid heat exchanger evaporator or an integrated auxiliary power unit (APU) stack cooler and evaporator coolant loop. In the latter-case, the waste heat source 42 can remove the need for an extra air-heated evaporator, and the “cooler” core can add heat to the space air.
As shown in
For example, during operation in A/C mode, by opening valve 59 (shown unshaded), closing valves 56 and 58 (shown in solid), opening valves 52 and 54, and closing valve 50, the APU coolant will not enter the low temperature loop 28 (which is heating the evaporator 26), and no coolant will pass to the liquid-cooled gas cooler 18 via the high temperature loop 19, while the coolant in the low temperature loop 28 rejects heat to the refrigerant in the evaporator 26 and receives heat from the air stream passing through the heater/cooler core 60. In some applications, it may be desirable for a small amount of cold liquid to pass through the valve 50 and the liquid-cooled gas cooler 18. This can allow the refrigerant temperature to fall below the ambient temperature, thus potentially improving system COP.
As shown in
The refrigeration system 10 of
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The embodiments described above and illustrated in the figures are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes are possible.
Claims
1. A refrigeration system having both a heating mode for providing heat to a load space and a cooling mode for removing heat from the load space, the system comprising:
- a first refrigerant circuit including a first heat exchanger for transferring heat from refrigerant of the first refrigerant circuit to air;
- a second refrigerant circuit including a second heat exchanger for transferring heat from air to refrigerant of the second refrigerant circuit; and
- a third refrigerant circuit including: a compressor for increasing pressure of refrigerant of the third refrigerant circuit; a third heat exchanger connected to the compressor for receiving refrigerant from the compressor, and connected to the first refrigerant circuit such that heat exchange can occur between the refrigerant traveling through the first refrigerant circuit and the refrigerant traveling through the third refrigerant circuit; an expansion device for reducing the pressure of the refrigerant of the third refrigerant circuit; and an evaporator connected to the expansion device, and connected to the second refrigerant circuit such that heat exchange can occur between the refrigerant traveling through the second refrigerant circuit and the refrigerant traveling through the third refrigerant circuit, the refrigerant traveling along the third refrigerant circuit in a common direction during operation in both the heating mode and the cooling mode; wherein refrigerant is prevented from moving between the first refrigerant circuit, the second refrigerant circuit, and the third refrigerant circuit during operation in the heating and cooling modes.
2. The refrigeration system of claim 1, wherein the third heat exchanger is a liquid-cooled gas cooler.
3. The refrigeration system of claim 2, further comprising an air-cooled gas cooler connected in series with the liquid-cooled gas cooler and to at least one of the compressor and the expansion device.
4. The refrigeration system of claim 1, wherein the evaporator is a liquid-heated evaporator.
5. The refrigeration system of claim 4, further comprising an air-heated evaporator connected in series with the liquid heated evaporator and to at least one of the expansion device and the compressor.
6. The refrigeration system of claim 1, further comprising a suction line heat exchanger connected to the third heat exchanger, the expansion valve, the evaporator, and the compressor along the third refrigerant circuit.
7. The refrigeration system of claim 1, wherein the refrigerant of the third refrigerant circuit is carbon dioxide.
8. The refrigeration system of claim 1, wherein the first heat exchanger and the second heat exchanger are combined in a single heat exchanger.
9. The refrigeration system of claim 1, further comprising a heat source separate from the first, second, and third refrigerant circuits for providing heat to the refrigeration system during operation in the heating mode.
10. A refrigeration system having both a heating mode for providing heat to a load space and a cooling mode for removing heat from the load space, the refrigeration system comprising:
- a first refrigerant circuit extending between a compressor, an evaporator, an expansion device, and a first heat exchanger, the first refrigerant circuit defining a flow path for a refrigerant traveling in a direction along the refrigerant circuit during operation of the refrigeration system in the heating mode and the cooling mode;
- a second refrigerant circuit extending between the condenser and a second heat exchanger, the second refrigerant circuit including a first refrigerant pump; and
- a third refrigerant circuit extending between the evaporator and the second heat exchanger, the third refrigerant circuit including a second refrigerant pump, the second refrigerant pump being operational during operation in the heating mode and being idle during operation in the cooling mode.
11. The refrigeration system of claim 10, wherein the second refrigerant circuit is separated from the first refrigerant circuit such that refrigerant is prevented from moving between the first and second refrigerant circuits, the second refrigerant circuit extending through the first heat exchanger such that heat exchange can occur between the refrigerant traveling through the first refrigerant circuit and a refrigerant traveling through the second refrigerant circuit.
12. The refrigeration system of claim 10, wherein the third refrigerant circuit is separated from the first refrigerant circuit such that refrigerant is prevented from moving between the first and third refrigerant circuits, the third refrigerant circuit extending through the evaporator such that heat exchange can occur between the refrigerant traveling through the first refrigerant circuit and a refrigerant traveling through the third refrigerant circuit.
13. The refrigeration system of claim 10, wherein the first refrigerant circuit includes a suction line heat exchanger.
14. The refrigeration system of claim 10, wherein the second heat exchanger includes a first heat exchanger core and a second heat exchanger core, the first heat exchanger core being associated with the second refrigerant circuit, the second heat exchanger core being associated with the third refrigerant circuit.
15. The refrigeration system of claim 10, further comprising a heat source separate from the first, second, and third refrigerant circuits for providing heat to the refrigeration system during operation in the heating mode.
16. The refrigeration system of claim 10, wherein the evaporator is a liquid-heated evaporator and the first heat exchanger is a liquid-cooled gas cooler.
17. The refrigeration system of claim 16, further comprising an air-cooled gas cooler connected in series with the liquid-cooled gas cooler.
18. The refrigeration system of claim 16, further comprising an air-heated evaporator connected in series with the liquid-heated evaporator.
19. A method of operating a refrigeration system, the method comprising the acts of:
- directing a refrigerant along a refrigerant circuit in a direction between a compressor, an evaporator, an expansion device, and a first heat exchanger during operation of the refrigeration system in a cooling mode;
- operating a first pump when the refrigeration system is operating in the cooling mode to circulate refrigerant through a second heat exchanger;
- transferring heat from a load space to the refrigerant in the refrigerant circuit when the refrigeration system is operating in the cooling mode;
- stopping the first pump when the refrigeration system is operating in a heating mode;
- directing the refrigerant along the refrigerant circuit in the direction during operation of the refrigeration system in the heating mode;
- operating a second pump when the refrigeration system is operating in the heating mode to circulate refrigerant through the second heat exchanger in heat exchange relation with the refrigerant of the refrigerant circuit; and
- transferring heat to the load space from the refrigerant in the refrigerant circuit when the refrigeration system is operating in the heating mode.
20. The method of claim 19, further comprising heating the refrigerant with a heat source separate from the refrigerant circuit when the refrigeration system is operating in the heating mode.
21. The method of claim 19, further comprising cooling the refrigerant using a suction line heat exchanger included along the refrigerant circuit.
22. The method of claim 19, further comprising heating the refrigerant with an air-heated evaporator and a liquid-heated evaporator when the refrigeration system is operating in the cooling mode.
23. The method of claim 19, further comprising cooling the refrigerant with an air-cooled condenser and a liquid-cooled condenser when the refrigeration system is operating in the heating mode.
Type: Application
Filed: Jun 6, 2008
Publication Date: Dec 11, 2008
Inventors: Jian-min Yin (Racine, WI), Michael J. Wilson (Racine, WI), Stephen B. Memory (Kenosha, WI), Samuel J. Collier (Danville, KY), Todd M. Bandhauer (Avondale Estates, GA)
Application Number: 12/134,263
International Classification: F25B 1/00 (20060101); F25B 7/00 (20060101); F25B 27/00 (20060101); F25D 17/00 (20060101);