Heat exchanger

Abstract

A heat exchanger includes: a plurality of primary tubes that receive a refrigerant distributed from a primary header tank; a primary turn tank and a secondary turn tank that receive the refrigerant from the primary tubes; and a plurality of secondary tubes that receive the refrigerant distributed from the secondary turn tank. An internal flow passage, which extends from the primary tubes to the secondary tubes via the primary turn tank and the secondary turn tank, has a primary region and at least one secondary region that are arranged one after another in a stacking direction. A pressure loss of the primary region and a pressure loss of the at least one secondary region are different from each other when a flow rate of the refrigerant in the primary region is the same as a flow rate of the refrigerant in the at least one secondary region.

What is claimed is: 
     
         1 . A heat exchanger comprising:
 a primary header tank that is configured to receive a refrigerant in a superheated gas state from an upstream-side flow passage located on an upstream side of the heat exchanger in a flow direction of the refrigerant;   a plurality of primary tubes that are configured to receive the refrigerant distributed from the primary header tank;   a primary turn tank that is configured to receive the refrigerant from the plurality of primary tubes;   a secondary turn tank that is configured to receive the refrigerant from the primary turn tank;   a plurality of secondary tubes that are configured to receive the refrigerant distributed from the secondary turn tank; and   a secondary header tank that is configured to receive the refrigerant in a subcooled liquid state from the plurality of secondary tubes and then output the refrigerant into a downstream-side flow passage located on a downstream side of the heat exchanger in the flow direction of the refrigerant, wherein:   an internal flow path, which extends from the plurality of primary tubes to the plurality of secondary tubes via the primary turn tank and the secondary turn tank, has a primary region and at least one secondary region that are arranged one after another in a stacking direction, in which the plurality of primary tubes are stacked and the plurality of secondary tubes are stacked, wherein a pressure loss of the primary region and a pressure loss of the at least one secondary region are different from each other when a flow rate of the refrigerant in the primary region is the same as a flow rate of the refrigerant in the at least one secondary region.   
     
     
         2 . The heat exchanger according to  claim 1 , wherein:
 the pressure loss in the at least one secondary region is higher than the pressure loss in the primary region; and   the at least one secondary region includes a pair of secondary regions between which the primary region is interposed.   
     
     
         3 . The heat exchanger according to  claim 1 , wherein the primary region and the at least one secondary region are formed in at least one of the primary turn tank or the secondary turn tank. 
     
     
         4 . The heat exchanger according to  claim 3 , wherein:
 a partition wall is placed between the primary turn tank and the secondary turn tank; and   the primary region and the at least one secondary region are formed in the partition wall.   
     
     
         5 . The heat exchanger according to  claim 4 , wherein:
 the partition wall has a plurality of communication holes which extend through the partition wall and are configured to conduct the refrigerant;   among the plurality of communication holes, one or more communication holes are formed in the at least one secondary region, and two or more communication holes are formed in the primary region; and   a number of the one or more communication holes formed in the at least one secondary region is smaller than a number of the two or more communication holes formed in the primary region.   
     
     
         6 . The heat exchanger according to  claim 5 , wherein:
 the at least one secondary region includes a pair of secondary regions; and   assuming that Nall is a number of virtual communication holes that would be present when the virtual communication holes, each having an identical configuration as each of the plurality of communication holes, were uniformly arranged in the primary region and the pair of secondary regions, and that Nsc is a virtual number of missing communication holes that would be present when the virtual communication holes were uniformly arranged in the primary region and the pair of secondary regions, provided that the missing communication holes were counted between one of the plurality of communication holes located at an outer end of the primary region and another one of the plurality of communication holes located at an inner end of one of the pair of secondary regions, a ratio Nsc/Nall is equal to or larger than 0.12; and   a total opening cross-sectional area of the plurality of communication holes actually arranged in the primary region and the pair of secondary regions is equal to or larger than 21.18 mm 2 .   
     
     
         7 . The heat exchanger according to  claim 4 , wherein:
 the partition wall has a plurality of communication holes which extend through the partition wall and are configured to conduct the refrigerant;   among the plurality of communication holes, one or more communication holes are formed in the at least one secondary region, and one or more communication holes are formed in the primary region; and   a total cross-sectional area of the one or more communication holes formed in the at least one secondary region is smaller than a total cross-sectional area of the one or more communication holes formed in the primary region.   
     
     
         8 . The heat exchanger according to  claim 3 , wherein an internal cross-sectional area of the at least one of the primary turn tank or the secondary turn tank is formed to vary at least in part along the stacking direction, and thereby the primary region and the at least one secondary region are formed accordingly. 
     
     
         9 . The heat exchanger according to  claim 8 , wherein the internal cross-sectional area of the at least one of the primary turn tank or the secondary turn tank is varied by providing a flow restrictor inside the at least one of the primary turn tank or the secondary turn tank. 
     
     
         10 . The heat exchanger according to  claim 8 , wherein the internal cross-sectional area of the at least one of the primary turn tank or the secondary turn tank is varied by varying an inner wall shape of the at least one of the primary turn tank or the secondary turn tank. 
     
     
         11 . The heat exchanger according to  claim 1 , wherein the primary region and the at least one secondary region are formed in the plurality of primary tubes and/or the plurality of secondary tubes. 
     
     
         12 . The heat exchanger according to  claim 11 , wherein among the plurality of primary tubes and the plurality of secondary tubes, an internal flow passage of each of the primary tubes and/or an internal flow passage of each of the secondary tubes arranged in the at least one secondary region is narrower than an internal flow passage of each of the primary tubes and/or an internal flow passage of each of the secondary tubes arranged in the primary region. 
     
     
         13 . The heat exchanger according to  claim 11 , wherein among the plurality of primary tubes and the plurality of secondary tubes, a number of the primary tubes and/or the secondary tubes arranged in the at least one secondary region is smaller than a number of the primary tubes and/or the secondary tubes arranged in the primary region.