Heat exchanger

Abstract

In a composite-type heat exchanger capable of exchanging heat among three types of fluids, an outside air passage is provided in a periphery of refrigerant tubes and coolant tubes, and the outside air passage includes outer fins that promote heat exchange among a refrigerant, an outside air and a coolant. The outer fins include refrigerant side heat connecting portions configured to thermally connect the refrigerant tubes, and coolant side heat connecting portions configured to thermally connect the refrigerant tubes and the coolant tubes. In a first core portion including most downstream refrigerant tubes which constitute a final path, which is the most downstream side path in a direction of the refrigerant flow, the refrigerant side heat connecting portions is larger in number than the coolant side heat connecting portions.

What is claimed is: 
     
         1 . A heat exchanger including:
 a plurality of first tubes in which a first fluid flows;   a plurality of second tubes in which a second fluid flows;   a heat exchange portion including the plurality of first tubes and the plurality of second tubes arranged in a stacked manner and configured to radiate heats of the first fluid and the second fluid to a third fluid;   a third fluid channel in which the third fluid flows, the third fluid channel being provided in a periphery of the plurality of first tubes and the plurality of second tubes; and   an outer fin arranged in the third fluid channel to promote a heat exchange between the first fluid and the third fluid and a heat exchange between the second fluid and the third fluid, wherein   the outer fin includes first heat connecting portions thermally connecting the plurality of first tubes, and second heat connecting portions thermally connecting the plurality of first tubes and the plurality of the second tubes,   the plurality of first tubes is divided into a plurality of groups,   the plurality of groups of the plurality of first tube are paths through which the first fluids distributed from a same space flow in a same direction,   the plurality of first tubes include most downstream first tubes which constitute a part of a final path that is a most downstream path in a flowing direction of the first fluid,   the heat exchange portion includes a first core portion including the most downstream first tubes, and   the first heat connecting portions are larger in number than the second heat connecting portions in the first core portion.   
     
     
         2 . The heat exchanger according to  claim 1 , wherein
 the first core portion includes the most downstream first tubes and at least one of the plurality of second tubes, and   the first core portion is provided with a heat-shielding portion located at a position corresponding to the second heat connecting portion of the outer fin the heat-shielding portion limiting heat transfer between the first fluid flowing in the most downstream first tubes and the second fluid flowing in the plurality of second tubes.   
     
     
         3 . The heat exchanger according to  claim 2 , wherein the heat-shielding portion includes a slit hole penetrating through the outer fin. 
     
     
         4 . The heat exchanger according to  claim 1 , wherein
 the first fluid is a refrigerant for a vapor compression refrigeration cycle, and   the heat exchange portion causes the refrigerant to concentrate.   
     
     
         5 . The heat exchanger according to  claim 1 , wherein
 the plurality of first tubes include second-most downstream first tubes that constitute a part of a path immediately before the final path in the flowing direction of the first fluid, and   the second-most downstream first tubes, through which the first fluid flows, and the plurality of second tubes, through which the second fluid flows, are arranged adjacent to each other such that the first fluid and the second fluid are same in flowing direction.   
     
     
         6 . The heat exchanger according to  claim 1 , wherein the plurality of first tubes and the plurality of second tubes are arranged alternately in a stacked manner except for the final path. 
     
     
         7 . The heat exchanger according to  claim 1 , wherein
 the heat exchange portion includes an upstream heat exchanging portion and a downstream heat exchanging portion arranged on a downstream side of the upstream heat exchanging portion in a flowing direction of the third fluid,   the most downstream first tubes constitute a part of the downstream heat exchanging portion, and   the first tubes and the second tubes in the upstream heat exchanging portion are arranged alternately in a stacked manner.   
     
     
         8 . The heat exchanger according to  claim 1 , wherein
 the heat exchange portion further includes a second core portion having the plurality of second tubes and the plurality of first tubes other than the most downstream first tubes, and   the plurality of first tubes and the plurality of second tubes in the second core portion are arranged alternately in a stacked manner.   
     
     
         9 . The heat exchanger according to  claim 1 , further comprising a dummy tube in which both the first fluid and the second fluid do not flow, the dummy tube being arranged between the most downstream first tubes and the plurality of second tubes. 
     
     
         10 . The heat exchanger according to  claim 1 , wherein
 the plurality of first tubes include second-most downstream first tubes which constitute a part of a path immediately before the final path in the flowing direction of the first fluid, and   a flow-channel total sectional area of the most downstream first tubes constituting the part of the final path is smaller than a flow-channel total sectional area of the second-most downstream first tubes.   
     
     
         11 . The heat exchanger according to  claim 1 , wherein
 the heat exchange portion includes an upstream heat exchanging portion and a downstream heat exchanging portion arranged on the downstream side of the upstream heat exchanging portion in the flowing direction of the third fluid,   the upstream heat exchanging portion includes a part of the most downstream first tubes of the first core portion,   the downstream heat exchanging portion includes a part of the most downstream first tubes of the first core portion), and   the part of the most downstream first tubes of the downstream heat exchanging portion is connected to the part of the most downstream first tubes of the upstream heat exchanging portion such that the first fluid flows from the downstream heat exchanging portion to the upstream heat exchanging portion in the most downstream first tubes.   
     
     
         12 . The heat exchanger according to  claim 1 , wherein
 the number of the second heat connecting portion is zero in the first core portion, and   the first core portion includes only the most downstream first tubes.