Patent Publication Number: US-9845979-B2

Title: Evaporator for a cascade refrigeration system

Description:
FIELD 
     The disclosure relates to an evaporator, and more particularly to an evaporator for a cascade refrigeration system. 
     BACKGROUND 
     Referring to  FIG. 1 , an existing single refrigerant refrigeration system includes a compressor  11 , a condenser  12  disposed downstream of and fluidly connected to the compressor  11 , an expansion valve  13  disposed downstream of and fluidly connected to the condenser  12 , and an evaporator  14  disposed downstream of the expansion valve  13  and upstream of the compressor  11 . 
     During operation of the existing single refrigerant refrigeration system, a refrigerant  101  flows into the compressor  11  and is compressed into a high-temperature and high-pressure gasified refrigerant  101 , after which it flows into the condenser  12  and is condensed into a normal-temperature and high-pressure liquefied refrigerant  101 . Next, the normal-temperature and high-pressure liquefied refrigerant  101  flows into the expansion valve  13  and is converted into a low-temperature and low-pressure liquefied refrigerant  101 . Afterwards, the low-temperature and low-pressure liquefied refrigerant  101  flows into the evaporator  14 , absorbs heat, and is converted into a low-temperature and low pressure gasified refrigerant  101  which then flows back into the compressor  11 . The existing single refrigerant refrigeration system is generally used in an air conditioning system and a refrigeration system. However, the cooling temperature of the existing single refrigerant refrigeration system ranges between 10° C. and 30° C. If a lower temperature refrigeration system is required, a dual refrigerant refrigeration system must be used. 
     Referring to  FIG. 2 , an existing dual refrigerant refrigeration system includes a liquefaction unit  15  and a cooling unit  16 . The liquefaction unit  15  includes a liquefaction compressor  151 , a liquefaction condenser  152  fluidly connected to the liquefaction compressor  151 , a liquefaction expansion valve  153  fluidly connected to the liquefaction condenser  152 , and a heat exchanger  154  fluidly interconnecting the liquefaction expansion valve  153  and the liquefaction compressor  151 . The cooling unit  16  includes a cooling compressor  161  fluidly connected to the heat exchanger  154 , a cooling expansion valve  162  fluidly connected to the heat exchanger  154 , and a cooling evaporator  163  fluidly connected to the cooling expansion valve  162  and the cooling compressor  161 . 
     The liquefaction unit  15  uses, for example, R 404  A or R  507  refrigerant  105 , which can be liquefied at high pressure and normal temperature. The cooling unit  16  uses, for example, R 23  refrigerant  106 , which cannot be liquefied at high pressure and normal temperature. By virtue of the heat exchanger  154 , the refrigerant  105  of the liquefaction unit  15  can liquefy the refrigerant  106  of the cooling unit  16  so that the refrigeration system can provide a cooling temperature of about −85° C. 
     When a wide range of the cooling temperature is required, the existing practice is to equip the refrigeration system with the single refrigerant refrigeration system and the dual refrigerant refrigeration system simultaneously. However, the production and maintenance costs of these two refrigeration systems are not only relatively high, but also they occupy a substantial space. 
     SUMMARY 
     Therefore, an object of the disclosure is to provide an evaporator for a multi-refrigerant refrigeration system that can alleviate the drawback of the prior art. 
     According to the disclosure, an evaporator for a cascade refrigeration system includes a casing and a plurality of circulation units disposed on the casing. Each of the circulation units includes a flow path formed in the casing, an inlet formed in the casing for entry of one of refrigerants into the casing and fluidly communicating with the flow path, and an outlet formed in the casing spaced apart from the inlet for exit of the one of the refrigerants out the casing and fluidly communicating with the flow path. The circulation units are independent from each other and do not fluidly communicate with each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiments with reference to the accompanying drawings, of which: 
         FIG. 1  is a schematic diagram illustrating a conventional single refrigerant refrigeration system; 
         FIG. 2  is a schematic diagram illustrating a conventional dual refrigerant refrigeration system; 
         FIG. 3  is a perspective view of a first embodiment of an evaporator for a cascade refrigeration system according to the disclosure; 
         FIG. 4  is a view similar to  FIG. 3 , but with a portion thereof being removed for the sake of clarity; 
         FIG. 5  is a sectional view of the first embodiment; 
         FIG. 6  is a schematic diagram illustrating the first embodiment in a state of use; 
         FIG. 7  is a perspective view of a second embodiment of an evaporator for a cascade refrigeration system according to the disclosure with a portion thereof being removed to illustrate an aspect of a first circulation unit thereof; 
         FIG. 8  is a view similar to  FIG. 7 , but taken from another angle to illustrate an aspect of a second circulation unit thereof; 
         FIG. 9  is a perspective view of a third embodiment of an evaporator for a cascade refrigeration system according to the disclosure; 
         FIG. 10  is a view similar to  FIG. 9 , but with a portion thereof being removed to illustrate aspect of first to third circulation units thereof; 
         FIG. 11  is a sectional view of a fourth embodiment of an evaporator for a cascade refrigeration system according to the disclosure; 
         FIG. 12  is a partly sectional view of a lower part of a casing of the fourth embodiment; and 
         FIG. 13  is a partly sectional view of an upper part of the casing of the fourth embodiment with a top wall thereof being removed for the sake of clarity. 
     
    
    
     DETAILED DESCRIPTION 
     Before the present disclosure is de scribed in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure. 
     Referring to  FIGS. 3 to 5 , an evaporator  2  for a cascade refrigeration system according to the first embodiment of the disclosure includes a substantially cylindrical-shaped casing  21  and first and second circulation units  3 ,  4 . 
     The casing  21  includes abase seat  210  and a connection seat  214  stacked on the base seat  210 . 
     The base seat  210  includes a base wall  211 , a first surrounding wall  212  surrounding the base wall  211 , and a first partition plate  213  protruding inwardly from the first surrounding wall  212 . 
     The connection seat  214  includes a connecting wall  215  connected to the first surrounding wall  212  opposite to the base wall  211 , a second surrounding wall  216  surrounding the connecting wall  215 , a second partition plate  217  protruding inwardly from the second surrounding wall  216 , and a top wall  218  connected to the second surrounding wall  216  opposite to the connecting wall  215 . 
     The first circulation unit  3  is disposed on the base seat  210 , and includes a first flow path  31  cooperatively defined by the base wall  211 , the first surrounding wall  212 , the first partition plate  213  and the connecting wall  215 , a first inlet  32  formed in the first surrounding wall  212  for entry of a refrigerant into the casing  21  and fluidly communicating with the first flow path  31 , and a first outlet  33  formed in the first surrounding wall  212  spaced apart from the first inlet  32  for exit of the refrigerant out of the casing  21  and fluidly communicating with the first flow path  31 . The first flow path  31  has a substantially C-shape (see  FIG. 5 ). 
     The second circulation unit  4  is disposed on the connection seat  214 , and includes a second flow path  41  cooperatively defined by the connecting wall  215 , the second surrounding wall  216 , the second partition plate  217  and the top wall  218 , a second inlet  42  formed in the second surrounding wall  216  for entry of another refrigerant into the casing  21  and fluidly communicating with the second flow path  41 , and a second outlet  43  formed in the second surrounding wall  216  spaced apart from the second inlet  42  for exit of the another refrigerant out of the casing  21  and fluidly communicating with the second flow path  41 . The second flow path  41  also has a substantially C-shape (see  FIG. 5 ). 
     By virtue of the connecting wall  215  separating the first and second flow paths  31 ,  41 , the first and second flow paths  31 ,  41  are independent from each other and do not fluidly communicate with each other. 
     Referring to  FIG. 6 , in combination with  FIGS. 3 and 5 , in actual practice, the evaporator  2  is suitable for use in a dual refrigerant refrigeration system. The dual refrigerant refrigeration system includes a first cooling unit  61 , a second cooling unit  62  and a switching valve  63 . In this embodiment, the first cooling unit  61  circulates R  507  refrigerant which is designated as  610  in the figure, and the second cooling unit  62  circulates R  23  refrigerant which is designated as  620  in the figure. 
     The first cooling unit  61  includes a first compressor  611  fluidly connected to the first outlet  33  of the evaporator  2 , a first condenser  612  disposed downstream of the first compressor  611  and upstream of the switching valve  63 , and a first expansion valve  613  disposed downstream of the switching valve  63  and upstream of the first inlet  32  of the evaporator  2 . 
     The second cooling unit  62  includes a second compressor  621  fluidly connected to the second outlet  43  of the evaporator  2 , a heat exchanger  622  fluidly connected to the first and second compressors  611 ,  621  and the second inlet  42  of the evaporator  2 , and a second expansion valve  623  fluidly connected to the heat exchanger  622  and the switching valve  63 . 
     When a cooling temperature of a single refrigerant refrigeration system is required, the second compressor  621  is turned off, and the switching valve  63  is switched for fluidly connecting the first condenser  612 , the first expansion valve  613  and the first inlet  32  of the evaporator  2 . 
     The refrigerant  610  flows into the first compressor  611  and is compressed into a high-temperature and high-pressure gasified refrigerant  610 , after which it flows into the first condenser  612  and is condensed into a normal-temperature and high-pressure liquefied refrigerant  610 . Next, the normal-temperature and high-pressure liquefied refrigerant  610  flows into the expansion valve  613  through the switching valve  63  and is converted into a low-temperature and low-pressure liquefied refrigerant  610 . Afterwards, the low-temperature and low-pressure liquefied refrigerant  610  enters the first inlet  32  into the evaporator  2 , absorbs heat, and is converted into a low-temperature and low-pressure gasified refrigerant  610  which then exits the first outlet  33  to flow back into the first compressor  611  to complete a cooling cycle of the first cooling unit  61 , so that the evaporator  2  can provide a cooling temperature of about −50° C. 
     When a cooling temperature of a dual refrigerant refrigeration system is required, the switching valve  63  is switched for fluidly connecting the first condenser  612 , the second expansion valve  623  and the heat exchanger  622 . The high-temperature and high-pressure refrigerant  610  exiting from the first compressor  611  is converted into the normal-temperature and high-pressure liquefied refrigerant  610  after passing through the first condenser  612 , and flows to the second expansion valve  623  through the switching valve  63 . Through the second expansion valve  623 , the normal-temperature and high-pressure liquefied refrigerant  610  is converted into a low-temperature and low-pressure liquefied refrigerant  610  which then flows into the heat exchanger  622 , absorbs heat and is converted into a low-temperature and low-pressure gasified refrigerant  610 . The low-temperature and low-pressure gasified refrigerant  610  then flows back into the first compressor  611  to complete a cooling cycle among the first compressor  611 , the first condenser  612 , the switching valve  63 , the second expansion valve  623  and the heat exchanger  622 . 
     When the temperature of the refrigerant  610  is sufficient to liquefy the refrigerant  620  during heat exchange in the heat exchanger  622 , the second compressor  621  is turned on to compress the refrigerant  620  that flows therein into a high-temperature and high-pressure gasified refrigerant  620  which then flows to the heat exchanger  622 . At the heat exchanger  622 , the low-temperature and low-pressure liquefied refrigerant  610  exchanges heat with the high-temperature and high-pressure gasified refrigerant  620  to convert into the low-temperature and low-pressure gasified refrigerant  610  that flows back into the first compressor  611 . The high-temperature and high-pressure gasified refrigerant  620 , on the other hand, is converted into a low-temperature and low-pressure liquefied refrigerant  620  that flows to the evaporator  2 . The low-temperature and low-pressure liquefied refrigerant  620  enters the second inlet  42  and exits the second outlet  43  of the second circulation unit  4  to flow back into the second compressor  621  to complete a cooling cycle among the second compressor  621 , the heat exchanger  622 , the evaporator  2 . The evaporator  2  can provide a cooling temperature of about −85° C. It should be noted that when the refrigerant  620  is circulating in the second flow path  41  of the second circulation unit  4 , the refrigerant  610  is temporarily stopped from circulating in the first flow path  31  of the first circulation unit  3 . 
     By using the first and second flow paths  31 ,  41  of the first and second circulation units  3 ,  4  which are independent from and not fluidly communicating with each other in the evaporator  2  for respectively circulating the refrigerant  610  and the refrigerant  620 , the cascade refrigeration system having the evaporator  2  of the disclosure simultaneously has the cooling capacity of a single refrigerant refrigeration system and a dual refrigerant refrigeration system, thereby reducing costs of the refrigeration system and space wastage. 
       FIGS. 7 and 8  illustrate an evaporator  2  for a cascade refrigeration system according to the second embodiment of the disclosure which is generally similar to the first embodiment. The differences between the first and second embodiments reside in that the casing  22  includes a casing body  221 , and a partition plate  222  disposed in the casing body  221  and extending in a height direction of the casing body  221  to divide the casing body  221  into two parts, and a plurality of flow guide plates  223  projecting transversely from two opposite sides of the partition plate  222  and spaced apart from each other in the height direction of the casing body  221 . In this embodiment, two spaced-apart flow guide plates  223  project from each of two opposite sides of the partition plate  222  into a corresponding one of the parts of the casing body  221 . The first and second circulation units  3 ,  4  are respectively disposed on the two parts of the casing body  221 . 
     The casing body  221 , the partition plate  222  and the flow guide plates  223  at one of the two opposite sides of the partition plate  222  cooperatively define the first flow path  31  of the first circulation unit  3 . The first flow path  31  of the first circulation unit  3  has a substantially S-shape (see  FIG. 7 ). The casing body  221 , the partition plate  222  and the flow guide plates  223  at the other side of the partition plate  222  cooperatively define the second flow path  41  of the second circulation unit  4 . The second flow path  41  of the second circulation unit  4  also has a substantially S-shape (see  FIG. 8 ). 
     The first inlet  32  and the first outlet  33  of the first circulation unit  3  are located on one side of the partition wall  222 , are spaced apart from each other in the height direction of the casing body  221 , and fluidly communicate with the first flow path  31 . The second inlet  42  and the second outlet  43  of the second circulation unit  4  are located on the other side of the partition wall  222 , are spaced apart from each other in the height direction of the casing body  221 , and fluidly communicate with the second flow path  41 . 
     The second embodiment has the same advantages as those of the first embodiment. 
       FIGS. 9 and 10  illustrate an evaporator  2  for a cascade refrigeration system according to the third embodiment of the disclosure which is generally similar to the second embodiment. However, in this embodiment, the casing  22  includes two spaced-apart partition plates  222  disposed in the casing body  221  and extending in a height direction of the casing body  221  to divide the casing body  221  into three parts, and the evaporator  2  further includes a third circulation unit  5  disposed on a middle one of the three parts of the casing body  221  and independent from the first and second circulation units  3 ,  4 . Moreover, the first, second and third circulation units  3 ,  4 ,  5  do not fluidly communicate with each other. Since the third circulation  5  has a structure similar to those of the first and second circulation units  3 ,  4 , details of the third circulation unit  5  are omitted herein. 
     In the third embodiment, aside from having the same advantages as those of the second embodiment, by virtue of the first, second and third circulation units  3 ,  4 ,  5  being independent from each other and not fluidly communicating with each other, the evaporator  2  of the disclosure can be applied to a triple refrigerant refrigeration system. 
       FIGS. 11 to 13  illustrate an evaporator  2  for a cascade refrigeration system according to the fourth embodiment of the disclosure which is generally similar to the second embodiment. The difference between the third and fourth embodiments resides in the structure of the casing  23 . In the fourth embodiment, the casing  23  includes a base wall  231 , atop wall  232  spaced apart from the base wall  231 , a partition wall  233  disposed between the base and top walls  231 ,  232  and dividing the casing  23  into upper and lower parts, a first protruding post  234  interconnecting the base and partition walls  231 ,  233  and located in the lower part of the casing  23 , a second protruding post  235  interconnecting the partition and top walls  233 ,  232  and located in the upper part of the casing  23 , a first inner surrounding wall  236  interconnecting the base and partition walls  231 , 233  and spacedly surrounding the first protruding post  234 , a second inner surrounding wall  237  interconnecting the partition and top walls  233 , 232  and spacedly surrounding the second protruding post  235 , and an outer surrounding wall  238  connected to peripheries of the base, top and partition walls  231 ,  232 ,  233 . Moreover, the casing  23  further includes a first cross wall  24  and a second cross wall  25 . The first cross wall  24  extends from the base wall  231  to the top wall  232 , interconnects the first protruding post  234  and the first inner surrounding wall  236 , and interconnects the second protruding post  235  and the second inner surrounding wall  237 . The second cross wall  25  extends from the base wall  231  to the top wall  232 , interconnects the first inner surrounding wall  236  and the outer surrounding wall  238 , and interconnects the second inner surrounding wall  237  and the outer surrounding wall  238 . 
     In this embodiment, the partition wall  233  has a first through hole  2330  immediately adjacent the first cross wall  24 , and a second through hole  2331  immediately adjacent the second cross wall  25 . The first protruding post  234 , the first inner surrounding wall  236 , the second protruding post  235  and the second inner surrounding wall  237  cooperatively de fine the first flow path  31  of the first circulation unit  3  that extends from the lower part to the upper part of the casing  23  through the first through hole  2330 . The first inner surrounding wall  236 , the second inner surrounding wall  237  and the outer surrounding wall  238  cooperatively define the second flow path  41  of the second circulation unit  4  that extends from the lower part to the upper part of the casing  23  through the second through hole  2331 . The second flow path  41  surrounds the first flow path  31 . 
     The first inlet  32  of the first circulation unit  3  is located between the base wall  231  and the partition wall  233  and extends through the outer surrounding wall  228 , the second cross wall  25  and the first inner surrounding wall  236  to fluidly communicate with the first flow path  31 . The second inlet  42  of the second circulation unit  4  is located between the base wall  231  and the partition wall  233  and extends through the outer surrounding wall  238  to fluidly communicate with the second flow path  41 . The second inlet  42  is proximate to the first inlet  32 . The first outlet  33  of the first circulation unit  3  is located between the partition wall  233  and the top wall  232  and extends through the second inner surrounding wall  237 , the second cross wall  25  and the outer surrounding wall  28  to fluidly communicate the first flow path  31  with an external environment. The second outlet  43  of the second circulation unit  4  is located between the partition wall  233  and the top wall  232  and extends through the outer surrounding wall  238  to fluidly communicate the second flow path  41  with the external environment. The second outlet  43  is proximate to the first outlet  33 . The first inlet  32  and the first outlet  33  are spaced apart from and aligned with each other in a top-bottom direction relative to the casing  23 . The second inlet  42  and the second outlet  43  are spaced apart from and aligned with each other in the top-bottom direction relative to the casing  23 . 
     The first inlet  32  of the first circulation unit  3  permits entry of a first refrigerant into the casing  23 . The first refrigerant enters the first inlet  32 , flows from the lower part to the upper part of the casing  23  through the first through hole  2330  and along the first flow path  31 , and exits out of the casing  23  through the first outlet  33 , as shown by the arrows in  FIGS. 12 and 13 . The second inlet  42  of the second circulation unit  4  permits entry of a second refrigerant into the casing  23 . The second refrigerant enters the second inlet  42 , flows from the lower part to the upper part of the casing  23  through the second through hole  2331  and along the second flow path  41 , and exits out of the casing  23  through the second outlet  43 , as shown by the arrows in  FIGS. 12 and 13 . 
     The fourth embodiment has the same advantages as those of the second embodiment. 
     Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least an implementation. The appearances of the phrase “in one embodiment” in various places in the specification may or may not be all referring to the same embodiment. Various features, aspects, and exemplary embodiments have been described herein. The features, aspects, and exemplary embodiments are susceptible to combination with one another as well as to variation and modification, as will be understood by those having skill in the art. 
     This disclosure is not limited to the disclosed exemplary embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.