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(11) | EP 3 073 218 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | WATER COOLED MICROCHANNEL CONDENSER |
| (57) The present application provides a condenser (300; 400) for a cascade refrigeration
system (100). The condenser may include an outer shell (310; 410), a microchannel
coil (330), an ammonia refrigerant (170) flowing through the microchannel coil, and
a water based coolant flowing through the outer shell for heat exchange with the ammonia
refrigerant.
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[0001] The present application and the resultant patent relate generally to refrigeration systems and more particularly relate to cascade refrigeration systems with a water cooled, microchannel condenser for use with a high side ammonia based cooling cycle.
[0002] Cascade refrigeration systems generally include a first side cooling cycle, or a high side, and a second side cooling cycle, or a low side cooling cycle. The two cooling cycles interface through a common heat exchanger, i.e., a cascade evaporator-condenser. The cascade refrigeration system may provide cooling at very low temperatures in a highly efficient manner.
[0003] Current refrigeration trends promote the use of carbon dioxide, ammonia, and other types of natural refrigerants instead of conventional hydrofluorocarbon based refrigerants. Moreover, there is an interest in improving the overall efficiency of such natural refrigerant based refrigeration systems at least as compared to the hydrofluorocarbon based systems. Further, there is a desire in limiting the overall charge of ammonia used therein so as to mitigate costs as well as potential usage risks and the like.
[0004] There is thus a desire for an improved refrigeration system such as a cascade refrigeration system that provides cooling with increased efficiency with natural refrigerants. Moreover, there is a desire for such improved cascade refrigeration systems to limit the overall charge of the ammonia based refrigerant therein in a safe and efficient manner.
[0005] The present application and the resulting patent thus provide a condenser for a cascade refrigeration system. The condenser may include an outer shell, a microchannel coil, an ammonia refrigerant flowing through the microchannel coil, and a water based coolant flowing through the outer shell for heat exchange with the ammonia refrigerant.
[0006] The present invention also provides a condenser for a cascade refrigeration system, comprising: an outer shell; and a microchannel coil; wherein: the microchannel coil comprises means for connecting to a source of an ammonia refrigerant for flowing through the microchannel coil; and the outer shell comprises means for connecting to a source of a water based coolant for flowing through the outer shell for heat exchange with the ammonia refrigerant. The microchannel coil may be provided at least partially within the outer shell.
[0007] The present application and the resultant patent further provide herein a cascade refrigeration system. The cascade refrigeration system may include a low side cycle and a high side cycle. The high side cycle may include a water cooled, microchannel heat exchanger. The water cooled, microchannel heat exchanger may comprise an outer shell and a microchannel coil therein. The outer shell may comprise a plate like shape or a cylinder like shape. The cascade outer shell comprises a shell fluid inlet and a shell fluid outlet. The microchannel coil may comprise aluminum. The microchannel coil may comprise a microchannel fluid inlet and a microchannel fluid outlet.
[0008] The present application and the resultant patent further provide herein a cascade refrigeration system. The cascade refrigeration system may include a low side cycle comprising a carbon dioxide refrigerant and a high side cycle comprising an ammonia refrigerant. The high side cycle may comprise a water cooled condenser with a microchannel coil therein.
[0009] The present invention also provides a method of refrigeration, comprising: providing a condenser having an outer shell and a microchannel coil; wherein: an ammonia refrigerant flows through the microchannel coil; and a water based coolant flows through the outer shell for heat exchange with the ammonia refrigerant.
[0010] These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims, which illustrate embodiments of the invention by way of example only.
Fig. 1 a schematic diagram of a cascade refrigeration system with a high side cycle and a low side cycle.
Fig. 2 is a schematic diagram of a water cooled, microchannel condenser as may be described herein.
Fig. 3 is a side view of the water cooled, microchannel condenser of Fig. 2.
Fig. 4 is a side sectional view of the water cooled, microchannel condenser of Fig. 2.
Fig. 5 is a perspective view of an alternative embodiment of a water cooled, microchannel condenser as may be described herein.
[0011] Referring now to the drawings, in which like numerals refer to like elements throughout the several views, Fig. 1 shows an example of a cascade refrigeration system 100. The cascade refrigeration system 100 may be used to cool any type of enclosure for use in, for example, supermarkets, cold storage, and the like. The cascade refrigeration system 100 also may be applicable to heating, ventilation, air conditioning, and/or different types of commercial or industrial applications. The overall cascade refrigeration system 100 may have any suitable size, shape, configuration, or capacity.
[0012] Generally described, the cascade refrigeration system may include a first side or a high side cycle 110 and a second side or a low side cycle 120. The high side cycle 110 may include one or more high side compressors 130, a high side condenser 140, and a high side expansion valve 150. Additional components also may be used herein. The high side cycle 110 may include a flow of a natural refrigerant 160. The natural refrigerant 160 may include a flow of ammonia 170. Other types of refrigerants may be used herein. The high side cycle 110 and the components therein may have any suitable size, shape, configuration, or capacity. Other components and other configurations may be used herein.
[0013] In most known cascade refrigeration systems, the high side condenser 140 typically may be a brazed plate heat exchanger, a copper tube and aluminum fin heat exchanger, and the like. The high side condenser 140 may be water cooled via a flow of water 180 and/or glycol based mixtures. Such known condensers may have a limited operating temperature gradient.
[0014] The low side cycle 120 may include one or more low side compressors 190, a low side vapor separator tank 200, a medium temperature loop 210, and a low temperature loop 220. The medium temperature loop 210 may include a pump 230 and one or more medium temperature evaporators 240. The low temperature loop 220 may include a low side expansion valve 250 and one or more low temperature evaporators 260. Additional components also may be used herein. The low side cycle 120 may include a natural refrigerant 160 in the form of a flow of carbon dioxide 270 and the like. Other types of refrigerants may be used herein. The components of the low side cycle 120 may have any suitable size, shape, configuration, or capacity. Other components and other configurations may be used herein.
[0015] The two cycles 110, 120 may interface through a cascade evaporator/condenser 280. Specifically, the respective flows of refrigerant 170, 270 may exchange heat via the cascade evaporator/condenser 280. The cascade evaporator/condenser 280 may have any suitable size, shape, configuration, or capacity. Other components and other configurations may be used herein.
[0016] The flow of ammonia 170 may be compressed by the high side compressor 130 and condensed in the high side condenser 140. The flow of ammonia 170 may pass through the high side expansion valve 150 and exchange heat in the cascade evaporator/condenser 280. Likewise, the carbon dioxide refrigerant 270 may be compressed by the low side compressor 190 and pass through the cascade evaporator/condenser 280 to exchange heat therein. The carbon dioxide refrigerant 270 may be separated in the vapor separator tank 200 and passed through the medium temperature loop 210 and the low temperature loop 220. The respective refrigeration cycles may then repeat herein.
[0017] Figs. 2-4 show an example of a water cooled, microchannel condenser 300. The water cooled, microchannel condenser 300 may include an outer shell 310. In this example, the outer shell 310 may take a plate like or a clam shell-like appearance 315. Other shapes and configurations may be used herein. The outer shell 310 may define an interior fluid space 320 therein. The water cooled, microchannel condenser 300 also may include a microchannel coil 330. The microchannel coil 330 may be made out of aluminum and/or alloys thereof in whole or in part for good heat exchange therethrough. The microchannel coil 330 may extend through the outer shell 310 and into the interior fluid space 320. The microchannel coil 330 may be considered to "float" within the interior fluid space 320.
[0018] The water cooled, microchannel condenser 300 may include a shell fluid inlet 340 and a shell fluid outlet 350. The shell fluid inlet 340 and the shelf fluid outlet 350 may be in communication with the interior fluid space 320. A number of web flow diverters 360 may be positioned within the interior fluid space 320 so as to promote the agitation of the fluid therein. The water cooled, microchannel condenser 300 may include a microchannel fluid inlet 370 and a microchannel fluid outlet 380. The microchannel fluid inlet 370 and the microchannel fluid outlet 380 may be in communication with the microchannel coil 330. The water cooled, microchannel condenser 300, and the components thereof, may have any suitable size, shape, configuration, or capacity. Other components and other configurations may be used herein.
[0019] In use, the flow of ammonia 170 flows to the water cooled, microchannel condenser 300 via the high side compressors 130. The flow of ammonia 170 enters via the microchannel fluid inlet 370, passes through the microchannel coil 330 within the interior fluid space 320, and exits via the microchannel fluid outlet 380. Likewise, the flow of water or other coolant enters the water cooled, microchannel condenser 300 via the shell fluid inlet 340. The water 180 fills the interior fluid space 220 and exchanges heat with the flow of ammonia 170 within the microchannel coil 330. The web flow diverters 360 may cause turbulence therein for enhanced heat transfer. The flow of water 180 then exits the interior fluid space 320 via the microchannel fluid outlet 380. The flow of water 180 may be reused or recycled as appropriate.
[0020] Fig. 5 shows an alternative embodiment of a water cooled, microchannel condenser 400 as may be described herein. Instead of the "clam shell" shape of the outer shell 310 described above, in this example an outer shell 410 may take more of a cylinder like shape 420 and the like. The outer shell 410 may take other shapes and sizes. The cylinder 420 defines the interior fluid space 320 for the microchannel coil 330 as well as the associated inlets 340, 370 and outlets 350, 380. Other components and other configurations may be used herein.
[0021] The use of the water cooled, microchannel condensers 300, 400 may provide improved efficiency for the overall cascade refrigeration system 100. The use of the microchannel coil 330 provides an ammonia charge reduction as compared to conventional condensers given the reduced cross-sectional area therein. Moreover, the microchannel coil 330 may provide higher overall operating temperature gradients given the use of the aluminum. The improved efficiency with the lower ammonia charge thus may provide for an overall cost advantage herein.
[0022] In addition to the flow of ammonia 170, a flow of carbon dioxide or other refrigerants may be used herein. If carbon dioxide is used, the microchannel coil 330 may be used but not called a condenser. Rather, the microchannel coil 330 may be positioned within the outer shell 310 in what may be described as a fluid (carbon dioxide and the like) to fluid (water and the like) heat exchanger. Other components and other configurations may be used herein.
[0023] It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
1. A condenser (300; 400) for a cascade refrigeration system (100), comprising:
an outer shell (310, 410); and
a microchannel coil (330); wherein:
the microchannel coil comprises means for connecting to a source of an ammonia refrigerant (170) for flowing through the microchannel coil; and
the outer shell comprises means for connecting to a source of a water based coolant for flowing through the outer shell for heat exchange with the ammonia refrigerant.
2. The condenser (300; 400) of claim 1, wherein the outer shell (310) comprises a plate
like shape (315).
3. The condenser (400) of claim 1, wherein the outer shell (410) comprises a cylinder
like shape (420).
4. The condenser (300; 400) of claim 1, 2 or 3, wherein the outer shell (310; 410) comprises
an interior fluid space (320).
5. The condenser (300; 400) of any preceding claim, wherein the outer shell (310; 410)
comprises a shell fluid inlet (340) and a shell fluid outlet (350).
6. The condenser (300; 400) of any preceding claim, wherein the outer shell (310; 410)
comprises a plurality of flow directors therein.
7. The condenser (300; 400) of any preceding claim, wherein the microchannel coil (330)
comprises aluminum.
8. The condenser (300; 400) of any preceding claim, wherein the microchannel coil (330)
comprises a microchannel fluid inlet (370) and a microchannel fluid outlet (380).
9. The condenser (300; 400) of any preceding claim, wherein the microchannel coil (330)
floats within the outer shell (310; 410).
10. The condenser (300; 400) of any preceding claim, wherein the water based coolant comprises
glycol.
11. The condenser (300; 400) of any preceding claim, wherein ammonia refrigerant (170)
may exchange heat with the water based coolant within the outer shell (310; 410).
12. The condenser (300; 400) of any preceding claim, wherein the ammonia refrigerant (170)
condenses within the outer shell (310; 410).
13. A cascade refrigeration system (100), comprising:
a low side cycle (120); and
a high side cycle (110);
wherein the high side cycle comprises a condenser (300; 400) according to any preceding claim.
14. The cascade refrigeration system (100) of claim 13, wherein the high side cycle (110)
comprises an ammonia refrigerant (170) or a carbon dioxide refrigerant.
15. A method of refrigeration, comprising:
providing a condenser (300; 400) having an outer shell (310; 410) and a microchannel coil (330); wherein:
an ammonia refrigerant (170) flows through the microchannel coil; and
a water based coolant flows through the outer shell for heat exchange with the ammonia refrigerant.