Patent Publication Number: US-2022221232-A1

Title: Heat exchanger

Description:
TECHNICAL FIELD 
     The present disclosure relates to a heat exchanger forming a condenser or an evaporator of a chiller such as a centrifugal chiller. 
     BACKGROUND ART 
     In the related art, a shell-tube heat exchanger, a fin-tube heat exchanger, a plate heat exchanger, a plate fin heat exchanger, or the like has been used as a heat exchanger that accompanies fluid phase changes, such as an evaporator or a condenser. The shell-tube heat exchanger is configured to allow a single-phase fluid to flow through a tube, heat and cool an external fluid, and evaporate and condense the external fluid. The fin-tube heat exchanger is configured to allow a gas to flow between fins outside a tube, heat and cool the fluid inside the tube, and evaporate and condense the fluid inside the tube. The plate heat exchanger or the plate fin heat exchanger is configured to allow a single-phase fluid to flow between first plates, heat and cool a fluid between second plates, and evaporate and condense the fluid. Among the heat exchangers, as the plate fin heat exchanger, for example, the following PTLs 1 to 3 have been reported. 
     CITATION LIST 
     Patent Literature 
     
         
         [PTL 1] PCT Japanese Translation Patent Publication No. 2007-520682 
         [PTL 2] Japanese Unexamined Patent Application Publication No. 2013-113479 
         [PTL 3] Japanese Unexamined Patent Application Publication No. 2013-113480 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In a case where a fluid is evaporated or condensed, the fluid undergoes a phase change, and thus a volume of the fluid changes significantly during a heat exchange process. In particular, in a portion (gas side) of a fluid flow path in which the internal fluid is in a gas phase state, a fluid volume in the fluid flow path becomes very large, and an excessive pressure loss may occur. On the other hand, if a fluid flow path is determined such that an excessive pressure loss does not occur in the flow on the gas side, a flow velocity on a liquid side (a portion where an internal fluid is in a liquid phase state) is significantly reduced, and thus a problem that the heat transfer performance deteriorates occurs. 
     In the case of the shell-tube heat exchanger, an unequal pitch is used in which a tube pitch and the like are changed such that the heat transfer performance and a pressure loss are appropriate in response to a volume change in the heat exchange process of a fluid. However, in this case, there is a problem that a volume of the shell-tube heat exchanger becomes large and thus an amount of fluids held on a side performing a phase change increases. On the other hand, the fin-tube heat exchanger, the plate heat exchanger, and the plate fin heat exchanger can be made more compact than the shell-tube heat exchanger, but shapes of heat exchangers currently reported do not correspond to a fluid volume change due to the phase change as described above. 
     The present disclosure has been made in view of such circumstances, and an object thereof is to provide a compact heat exchanger capable of suppressing the occurrence of excessive pressure loss and ensuring an appropriate flow velocity in correspondence to a volume change of a fluid due to a phase change. 
     Solution to Problem 
     In order to solve the above problems, the present disclosure employs the following means. 
     According to the present disclosure, there is provided a heat exchanger including a flow path having an inflow port through which a fluid flows thereinto and an outflow port through which the fluid having flowed in flows out therefrom, and in which a phase change occurs from a liquid phase to a gas phase between the inflow port and the outflow port, in which a resistance shape is formed inside the flow path such that a magnitude of a flow path resistance applied to a flow of the fluid is smaller on the outflow port side than on the inflow port side. 
     If the fluid flowing into the flow path undergoes a phase change (evaporated) from a liquid phase to a gas phase through heat exchange in the flow path, a fluid volume increases. In this case, on the outflow port side, an excessive pressure loss may occur due to an increase in the fluid volume. However, in the heat exchanger according to a first aspect of the present disclosure, the resistance shape is formed inside the flow path such that the magnitude of the flow path resistance applied to the flow of the fluid becomes smaller on the outflow port side than on the inflow port side (for example, in five stages). Therefore, on the outflow port side (gas side), the magnitude of the flow path resistance applied to the flow of the fluid is small, and thus the occurrence of excessive pressure loss can be suppressed. On the other hand, on the inflow port side (liquid side), since the magnitude of the flow path resistance applied to the flow of the fluid is large, it is possible to prevent a flow velocity of the fluid from being significantly reduced (that is, an appropriate flow velocity can be ensured) and also to promote turbulence. As described above, in the heat exchanger according to the first aspect of the present disclosure, it is possible to suppress the occurrence of excessive pressure loss and promote turbulence in correspondence to a volume change of the fluid due to a phase change. Therefore, such a heat exchanger is a heat exchanger having high heat transfer performance (evaporation heat transfer performance). Since it is only necessary to form the specific resistance shape inside the flow path, the heat exchanger can be made compact. 
     According to the present disclosure, there is provided a heat exchanger including a flow path having an inflow port through which a fluid flows thereinto and an outflow port through which the fluid having flowed in flows out therefrom, and in which a phase change occurs from a gas phase to a liquid phase between the inflow port and the outflow port, in which a resistance shape is formed inside the flow path such that a magnitude of a flow path resistance applied to a flow of the fluid is larger on the outflow port side than on the inflow port side. 
     If the fluid flowing into the flow path undergoes a phase change (condensed) from a gas phase to a liquid phase through heat exchange in the flow path, a fluid volume decreases. In this case, an excessive pressure loss may occur on the inflow port side due to an increase in the fluid volume. However, in the heat exchanger according to a second aspect of the present disclosure, the resistance shape is formed inside the flow path such that the magnitude of the flow path resistance applied to the flow of the fluid becomes larger on the outflow port side than on the inflow port side (for example, in five stages). Therefore, on the inflow port side (gas side), the magnitude of the flow path resistance applied to the fluid flow is small, and thus the occurrence of excessive pressure loss can be suppressed. On the other hand, on the outflow port side (liquid side), since the magnitude of the flow path resistance applied to the flow of the fluid is large, it is possible to prevent a flow velocity of the fluid from being significantly reduced (that is, an appropriate flow velocity can be ensured) and also to promote turbulence. As described above, in the heat exchanger according to the second aspect of the present disclosure, it is possible to suppress the occurrence of excessive pressure loss and promote turbulence in correspondence to a volume change of the fluid due to a phase change. Therefore, such a heat exchanger is a heat exchanger having high heat transfer performance (condensation performance). Since it is only necessary to form the specific resistance shape inside the flow path, the heat exchanger can be made compact. 
     In the heat exchanger, the resistance shape is preferably formed by a plate forming the flow path or a plurality of fins provided on the plate. 
     As described above, the resistance shape formed inside the flow path may be formed by the plate forming the flow path (for example, in a plate heat exchanger) or the plurality of fins provided on the plate (for example, in a plate fin heat exchanger). Specifically, in the portion where the flow path resistance is increased, the plates and fins are arranged perpendicular to the fluid flow direction. On the other hand, in a portion where the flow path resistance is reduced, the plates and fins are arranged parallel to the fluid flow direction. With this configuration, the resistance shape can be formed. Therefore, the heat exchangers of the present disclosure are particularly suitably applicable to the plate heat exchanger or the plate fin heat exchanger. Since the plate heat exchanger or the plate fin heat exchanger can be made compact, if the heat exchanger of the present disclosure is applied to the plate heat exchanger or the plate fin heat exchanger, the heat transfer performance is improved and the heat exchanger can be made compact. 
     The heat exchanger preferably further includes a separate flow path that is provided adjacent to the flow path and is subjected to heat exchange with the fluid flowing through the flow path. 
     In the heat exchanger of the present disclosure, as described above, the separate flow path is provided, and thus heat exchange can be performed between the fluid flowing through the flow path and the fluid flowing through the separate flow path. 
     In the heat exchanger, a resistance shape is preferably formed inside the separate flow path such that the same flow path resistance is applied between an inflow port through which a fluid flows thereinto to flow in the separate flow path and an outflow port through which the fluid having flowed in flows out therefrom. 
     As described above, if the separate flow path in which the internal resistance shape is a resistance shape that applies the constant magnitude of the flow path resistance to the flow of the fluid may be combined with the flow path, the present disclosure is suitably applicable to the heat exchanger having a configuration in which one fluid is in a single phase and the other fluid undergoes a phase change. 
     In the heat exchanger, a resistance shape is preferably formed inside the separate flow path such that a flow path resistance is smaller at an inflow port through which a fluid flows thereinto to flow in the separate flow path than at an outflow port through which the fluid having flowed in flows out therefrom or is larger than at the inflow port than at the outflow port. 
     In the heat exchanger of the present disclosure, for example, the flow path in the first aspect and the flow path in the second aspect may be combined with each other. That is, the heat exchanger of the present disclosure is suitably applicable to a heat exchanger in which one fluid is evaporated in the flow path and the other fluid is condensed in the flow path. 
     Advantageous Effects of Invention 
     The heat exchanger of the present disclosure is a compact heat exchanger that can suppress the occurrence of excessive pressure loss and ensure an appropriate flow velocity in correspondence to a volume change of a fluid due to a phase change. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective exploded view illustrating a structure of a heat exchanger (plate fin heat exchanger) according to a first embodiment of the present disclosure. 
         FIG. 2  is a plan view illustrating a flow path in the heat exchanger according to the first embodiment of the present disclosure. 
         FIG. 3  is a plan view illustrating a flow path in a heat exchanger according to a second embodiment of the present disclosure. 
         FIG. 4  is an image view in which a flow path and a separate flow path in a heat exchanger according to a third embodiment of the present disclosure are viewed from a side surface in a longitudinal direction. 
         FIG. 5  is an image view in which a flow path and a separate flow path in a heat exchanger according to a fourth embodiment of the present disclosure are viewed from a side surface in a longitudinal direction. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of a heat exchanger according to the present disclosure will be described with reference to the drawings. 
     In the following embodiments, a case where the heat exchanger according to the present disclosure is applied to a plate fin heat exchanger will be described as an example. 
     First Embodiment 
     Hereinafter, a first embodiment of the present disclosure will be described with reference to  FIGS. 1 and 2 . 
       FIG. 1  is a perspective exploded view illustrating a structure of a heat exchanger (plate fin heat exchanger) according to the present embodiment. A heat exchanger  1  illustrated in  FIG. 1  is used for a condenser or an evaporator of a chiller such as a centrifugal chiller. The heat exchanger  1  has a structure in which plates (first plate)  2   a  and plates (second plate)  2   b  are alternately laminated and joined, bosses  3   a  and  3   b  are attached to the first plate  2   a  at the starting end, and a cover plate  4  is attached to the first plate  2   a  at the trailing end. Inner fins  5   a  and  5   b  are respectively provided at surfaces of the first plate  2   a  and the second plate  2   b  on the cover plate  4  side. 
     A fluid (first fluid)  6  flows into the heat exchanger  1  from the boss  3   a , and a fluid (second fluid)  7  flows thereinto from the boss  3   b . The first fluid  6  is circulated in a flow path  8  formed between the second plate  2   b  and the inner fin  5   a . The second fluid  7  is circulated in a separate flow path  9  that is formed between the first plate  2   a  and the inner fin  5   b  and is adjacent to the flow path  8 . 
     With such a configuration, the heat exchanger  1  has a structure in which the flow path  8  for the first fluid  6  and the separate flow path  9  for the second fluid  7  are alternately disposed and heat exchange occurs between the two fluids  6  and  7 . 
     Next, the flow path  8  of the present embodiment will be described in more detail with reference to  FIG. 2 . 
       FIG. 2  is a plan view illustrating the flow path  8  in the heat exchanger  1  of the present embodiment. 
     As illustrated in  FIG. 2 , the flow path  8  has an inflow port  10  through which the first fluid  6  flows thereinto and an outflow port  11  through which the first fluid  6  having flowed in flows out therefrom. In the flow path  8 , the first fluid  6  undergoes a phase change from a liquid phase to a gas phase between the inflow port  10  and the outflow port  11 . That is, the heat exchanger  1  is used as an evaporator evaporating a refrigerant. 
     A resistance shape  12  is formed inside the flow path  8  such that a magnitude of a flow path resistance applied to the flow of the first fluid  6  is smaller on the outflow port  11  side than on the inflow port  10  side. The resistance shape  12  is formed such that the magnitude of the flow path resistance becomes smaller in five stages from the inflow port  10  side to the outflow port  11  side. In the present embodiment, the resistance shape  12  is formed by a plurality of fins  13  provided on the first plate  2   a.    
     Specifically, in a portion (liquid side) where the flow path resistance is increased, the fins  13  are arranged perpendicular to a flow direction of the fluid  6 , and a length of the fins  13  (a length in the direction perpendicular to the flow direction of the fluid  6 ) is reduced from the inflow port  10  side toward the outflow port  11  side. On the other hand, in a portion (gas side) where the flow path resistance is reduced, the fins  13  are arranged parallel to the flow direction of the fluid  6 , and are arranged such that the number of fins  13  becomes smaller from the inflow port  10  side toward the outflow port  11  side. 
     According to the present embodiment, the following effects are achieved by the configuration described above. 
     In the heat exchanger  1  according to the present embodiment, the resistance shape  12  is formed such that the magnitude of the flow path resistance applied to the flow of the fluid  6  inside the flow path  8  becomes smaller in five stages from the inflow port  10  side to the outflow port  11  side. Therefore, on the outflow port  11  side (gas side), the magnitude of the flow path resistance applied to the flow of the fluid  6  is small, and thus the occurrence of excessive pressure loss can be suppressed. On the other hand, on the inflow port  10  side (liquid side), since the magnitude of the flow path resistance applied to the flow of the fluid  6  is large, it is possible to prevent a flow velocity of the fluid  6  from being significantly reduced (that is, an appropriate flow velocity can be ensured) and also to promote turbulence. As described above, in the heat exchanger  1  according to the present embodiment, it is possible to suppress the occurrence of excessive pressure loss and promote turbulence in correspondence to a volume change of the fluid  6  due to a phase change. Therefore, such a heat exchanger  1  is the heat exchanger  1  having high heat transfer performance (evaporation heat transfer performance). Since it is only necessary to form the specific resistance shape  12  inside the flow path  8 , the heat exchanger  1  can be made compact. 
     The resistance shape  12  formed inside the flow path  8  may be formed by the plurality of fins  13  provided on the first plate  2   a  (in the plate fin heat exchanger). Therefore, the heat exchanger  1  of the present embodiment is particularly suitably applicable to the plate fin heat exchanger. Since the plate fin heat exchanger can be made compact, if the heat exchanger  1  of the present embodiment is applied to the plate fin heat exchanger, the heat transfer performance is improved and the heat exchanger  1  becomes compact. 
     The resistance shape  12  may also be formed by the first plate  2   a  forming the flow path  8  (in the plate heat exchanger). Therefore, the heat exchanger  1  of the present embodiment is also suitably applicable to the plate heat exchanger. Since the plate heat exchanger can also be made compact, if the heat exchanger  1  of the present embodiment is applied to the plate heat exchanger, the heat transfer performance is improved and the heat exchanger  1  becomes compact as described above. 
     In the present embodiment, as illustrated in  FIG. 2 , as an example, a case has been described in which the resistance shape  12  is formed such that the magnitude of the flow path resistance applied to the flow of the fluid  6  becomes smaller in five stages from the inflow port  10  side to the outflow port  11  side, but the present disclosure is not limited to this. The magnitude of the flow path resistance may become smaller from the inflow port  10  side to the outflow port  11  side, preferably in three to ten stages. 
     Second Embodiment 
     Next, a second embodiment of the present disclosure will be described with reference to  FIG. 3 . 
     A fundamental configuration of the present embodiment is basically the same as that of the first embodiment, but is different from that of the first embodiment in that a first fluid  26  undergoes a phase change from a gas phase to a liquid phase in a flow path  28 , and in terms of a configuration of a resistance shape  22 . Therefore, in the present embodiment, this different portion will be described, and the description of other overlapping portions will be omitted. 
     The same constituents as those in the first embodiment are given the same reference numerals, and the repeated description thereof will be omitted. 
       FIG. 3  is a plan view illustrating a flow path  28  in a heat exchanger  21  of the present embodiment. 
     In the flow path  28  illustrated in  FIG. 3 , the first fluid  26  undergoes a phase change from a gas phase to a liquid phase between the inflow port  10  and the outflow port  11 . That is, the heat exchanger  1  is used as a condenser condensing a refrigerant. The resistance shape  22  is formed inside the flow path  28  such that the magnitude of the flow path resistance applied to the flow of the first fluid  26  is larger on the outflow port  11  side than on the inflow port  10  side. The resistance shape  22  is formed such that the magnitude of the flow path resistance becomes larger in five stages from the inflow port  10  side to the outflow port  11  side. The resistance shape  22  is formed by a plurality of fins  13  provided on the first plate  2   a  in the same manner as in the first embodiment. 
     Specifically, in a portion (gas side) where the flow path resistance is reduced, the fins  13  are arranged parallel to the flow direction of the fluid  26 , and are arranged such that the number of the fins  13  becomes larger from the inflow port  10  side toward the outflow port  11  side. On the other hand, in a portion (liquid side) where the flow path resistance is increased, the fins  13  are arranged perpendicular to the flow direction of the fluid  26 , and a length of the fins  13  (a length in the direction perpendicular to the flow direction of the fluid  26 ) is increased from the inflow port  10  side toward the outflow port  11  side. 
     According to the present embodiment, the following effects are achieved by the configuration described above. 
     In the heat exchanger  21  according to the present embodiment, the resistance shape  22  is formed such that the magnitude of the flow path resistance applied to the flow of the fluid  26  inside the flow path  28  becomes larger in five stages from the inflow port  10  side to the outflow port  11  side. Therefore, on the inflow port  10  side (gas side), the magnitude of the flow path resistance applied to the flow of the fluid  26  is small, and thus the occurrence of excessive pressure loss can be suppressed. On the other hand, on the outflow port  11  side (liquid side), since the magnitude of the flow path resistance applied to the flow of the fluid  26  is large, it is possible to prevent the flow velocity of the fluid  26  from being significantly reduced (that is, an appropriate flow velocity can be ensured) and also to promote turbulence. As described above, in the heat exchanger  21  according to the present embodiment, it is possible to suppress the occurrence of excessive pressure loss and promote turbulence in correspondence to a volume change of the fluid  26  due to a phase change. Therefore, such a heat exchanger  21  is the heat exchanger  21  having high heat transfer performance (condensation performance). Since it is only necessary to form the specific resistance shape  22  inside the flow path  28 , the heat exchanger  21  can be made compact. 
     In the present embodiment, as illustrated in  FIG. 3 , as an example, a case has been described in which the resistance shape  22  is formed such that the magnitude of the flow path resistance applied to the flow of the fluid  26  becomes larger in five stages from the inflow port  10  side to the outflow port  11  side, but the present disclosure is not limited to this. The magnitude of the flow path resistance may become larger from the inflow port  10  side to the outflow port  11  side, preferably in three to ten stages. 
     Third Embodiment 
     Next, a third embodiment of the present disclosure will be described with reference to  FIG. 4 . 
     A fundamental configuration of the present embodiment is basically the same as that of the second embodiment, but is different from that of the second embodiment in that a resistance shape  42  that applies the same flow path resistance between an inflow port  40  and an outflow port  41  is formed inside a separate flow path  49 . Therefore, in the present embodiment, this different portion will be described, and the description of other overlapping portions will be omitted. 
     The same constituents as those in the second embodiment are given the same reference numerals, and the repeated description thereof will be omitted. In  FIG. 4 , shapes of the resistance shapes  22  and  42  are conceptually illustrated, but this is just an image diagram. 
       FIG. 4  is an image diagram in which the flow path  28  and the separate flow path  49  in the heat exchanger  31  according to the present embodiment are viewed from the side surface in the longitudinal direction. As illustrated in  FIG. 4 , in the flow path  28 , a first fluid  26  undergoes a phase change from a gas phase to a liquid phase between the inflow port  10  and the outflow port  11 . The resistance shape  22  is formed inside the flow path  28  such that the magnitude of the flow path resistance applied to the flow of the first fluid  26  is larger on the outflow port  11  side than on the inflow port  10  side. 
     On the other hand, the separate flow path  49  has the inflow port  40  through which a second fluid  47  flows thereinto and an outflow port  41  through which the second fluid  47  having flowed in flows out therefrom. In the separate flow path  49 , the second fluid  47  does not undergo a phase change between the inflow port  40  and the outflow port  41 , and is circulated in the separate flow path  49  in a liquid phase (that is, a single phase). The resistance shape  42  that applies the same flow path resistance between the inflow port  40  and the outflow port  41  is formed inside the separate flow path  49 . 
     According to the present embodiment, the following effects are achieved by the configuration described above. 
     As described above, the separate flow path  49  in which the internal resistance shape  42  is the resistance shape  42  that applies the constant magnitude of the flow path resistance to the flow of the fluid  47  may be combined with the flow path  28  according to the second embodiment described above. That is, the present disclosure is suitably applicable to the heat exchanger  31  having a configuration in which one fluid  47  is in a single phase and the other fluid  26  undergoes a phase change. 
     Fourth Embodiment 
     Next, a fourth embodiment of the present disclosure will be described with reference to  FIG. 5 . 
     A fundamental configuration of the present embodiment is basically the same as that of the third embodiment, but is different from that of the third embodiment in terms of a configuration of a resistance shape  52  formed inside a separate flow path  59 . Therefore, in the present embodiment, this different portion will be described, and the description of other overlapping portions will be omitted. 
     The same constituents as those in the third embodiment are given the same reference numerals, and the repeated description thereof will be omitted. In  FIG. 5 , shapes of the resistance shapes  22  and  52  are conceptually illustrated, but this is just an image diagram. 
       FIG. 5  is an image diagram in which the flow path  28  and the separate flow path  59  in the heat exchanger  51  according to the present embodiment are viewed from the side surface in the longitudinal direction. As illustrated in  FIG. 5 , in the separate flow path  59  according to the present embodiment, the second fluid  57  undergoes a phase change from a liquid phase to a gas phase between the inflow port  40  and the outflow port  41 . The resistance shape  52  is formed inside the separate flow path  59  such that the flow path resistance of the outflow port  41  is smaller than that of the inflow port  40 . That is, a configuration of the separate flow path  59  is substantially the same as the configuration of the flow path  8  in the first embodiment. 
     According to the present embodiment, the following effects are achieved by the configuration described above. 
     In the heat exchanger  51  of the present embodiment, for example, the flow path  8  (separate flow path  59 ) in the first embodiment may be combined with the flow path  28  in the second embodiment. That is, the heat exchanger  51  of the present embodiment is suitably applicable to the heat exchanger  51  having a configuration in which one fluid  57  is evaporated in the flow path  8  (separate flow path  59 ) and the other fluid  26  is condensed in the flow path  28 . 
     In the embodiments described above, the case where the heat exchanger of the present disclosure is applied to the plate fin heat exchanger has been described as an example, but the present disclosure is not limited to this. Specifically, the heat exchanger of the present disclosure is also applicable to a plate heat exchanger, a fin-tube heat exchanger, and the like. The heat exchanger of the present disclosure is preferably applied to a plate heat exchanger or a plate fin heat exchanger. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1 , 21 , 31 , 51  Heat exchanger 
               2   a  Plate (first plate) 
               2   b  Plate (second plate) 
               3   a ,  3   b  Boss 
               4  Cover plate 
               5   a ,  5   b  Inner fin 
               6 , 26  Fluid (first fluid) 
               7 , 47 , 57  Fluid (second fluid) 
               8 , 28  Flow path 
               9 , 49 , 59  Separate flow path 
               10 ,  40  Inflow port 
               11 , 41  Outflow port 
               12 ,  22 ,  42 ,  52  Resistance shape 
               13  Fin