Heat exchanger and vehicle air-conditioning system

Abstract

The invention concerns a heat exchanger with an arrangement of parallel-guided flat tubes (1a, 1b) which are intended to conduct coolant which evaporates. Fins (2) are arranged between the tubes which form air guide slots in the direction perpendicular to the course of the tubes, and thus define the flow direction of air to be cooled. The tubes form at least two assemblies (11) which are arranged behind each other in the air flow direction (3). The assemblies (11, 12) differ in the free inner cross-section area (W1, W2) of the tubes (1a, 1b) for the coolant.

1 . A heat exchanger comprising:
 a coolant inlet;   a coolant outlet;   parallel-guided flat tubes configured to conduct a coolant which evaporates; and   fins arranged between the tubes which form air guide slots in the direction perpendicular to the course of the tubes, thereby defining a flow direction of air flowing through,   wherein the parallel-guided flat tubes form at least two assemblies through which coolant flows successively and which are arranged behind each other in the air flow direction, and   wherein the assemblies differ in a size of an inner cross-section area of the respective tubes of the assemblies, and the tubes adjacent to the coolant outlet have a larger cross-section area than the tubes adjacent to the coolant inlet.   
     
     
         2 . The heat exchanger according to  claim 1 , further comprising an upper and a lower collector between which the parallel-guided flat tubes run, wherein tubes with parallel flow form a pass and coolant flows through the passes successively, wherein the coolant inlet and the coolant outlet are arranged on one of the upper and lower collectors. 
     
     
         3 . The heat exchanger according to  claim 2 , wherein the upper and lower collectors have openings in which the ends of the tubes are tightly welded. 
     
     
         4 . The heat exchanger according to  claim 2 , wherein each of the two collectors forms a chamber or several chambers separated from each other by partition walls, such that the tubes form at least two passes through which coolant flows successively. 
     
     
         5 . The heat exchanger according to  claim 2 , wherein the passes differ in the number of tubes and/or in the crosssection of the tubes through which coolant flows, wherein, in the pass adjacent to the coolant outlet, a sum of the crosssection areas of the tubes which contribute to this pass has a greater value than in the pass adjacent to the coolant inlet by 1.2 to 1.6 times. 
     
     
         6 . The heat exchanger according to  claim 3 , wherein the number of tubes arranged behind each other in the air flow direction is different in the first and in the second assembly. 
     
     
         7 . The heat exchanger according to  claim 1 , wherein tubes form precisely two passes through which coolant flows successively, with a first pass having tubes with smaller cross-section area and a second pass having tubes with a larger cross-section area. 
     
     
         8 . The heat exchanger according to  claim 1 , wherein the tubes form more than two passes through which coolant flows successively, and in the coolant flow direction, sums of the cross-section areas of the respective passes form a monotonously rising sequence. 
     
     
         9 . The heat exchanger according to  claim 1 , wherein the tubes of one of the at least two assemblies have the same cross-section areas. 
     
     
         10 . The heat exchanger according to  claim 1 , wherein one of the at least two assemblies has a plurality of passes with successive flow, and successive passes have more tubes than preceding passes, so that a sum of the cross-section areas of the tubes increases. 
     
     
         11 . The heat exchanger according to  claim 1 , wherein several tubes are joined together into a plurality of structural units, wherein the structural units in cross-section have an oblong form and the fins are arranged between adjacent units. 
     
     
         12 . A vehicle air-conditioning system with a heat exchanger according to  claim 1 , wherein air and coolant are in co-flow and the side of the heat exchanger facing the coolant inlet is arranged facing the air inlet. 
     
     
         13 . A vehicle air-conditioning system with a heat exchanger according to  claim 1 , wherein and coolant are in contra-flow, and the side of the heat exchanger facing the coolant outlet is arranged facing the air inlet.