Heat exchanger and refrigeration cycle apparatus including the same

Abstract

A heat exchanger includes at least one flat tube configured to allow a refrigerant mixture inclusive of HFO1123, R32, and HFO1234yf to flow therethrough as a heat medium. The flat tube includes a plurality of flow paths for the heat medium. Each of the plurality of flow paths has a round rectangular shape in cross section, the round rectangular shape being defined by a pair of longitudinal line segments opposed to each other, a pair of lateral line segments opposed to each other, and a set of four rounded corners, each of the rounded corners being a segment of a circumference of a circle. The pair of longitudinal line segments are intersects with the pair of lateral line segments at the rounded corners. The round rectangular shape is configured to satisfy 0.005≦r/d≦0.8 where r is a radius of the circle, and d is a distance between the pair of longitudinal line segments opposed to each other.

1 . A heat exchanger comprising:
 a flat tube configured to allow a refrigerant mixture inclusive of HFO1123, R32, and HFO1234yf to flow therethrough as a heat medium,   the flat tube having a plurality of flow paths for the heat medium, and   each of the plurality of flow paths having a rectangular shape in cross section, the rectangular shape being defined by a pair of longitudinal line segments opposed to each other, a pair of lateral line segments opposed to each other, and a set of four rounded corners, each of the rounded corners being a segment of a circumference of a circle, the pair of longitudinal line segments being intersects with the pair of lateral line segments at the rounded corners,   the rectangular shape being configured to satisfy
   0.005≦r/d≦0.8
 
   
       where r is a radius of the circle, and d is a distance between the pair of longitudinal line segments opposed to each other. 
     
     
         2 . The heat exchanger of  claim 1 , wherein a mixture ratio of HFO1234yf in the refrigerant mixture ranges from 50% to 90% by weight. 
     
     
         3 . The heat exchanger of  claim 1 , wherein the longitudinal line segments have a protrusion extending in a longitudinal direction of the flat tube. 
     
     
         4 . The heat exchanger of  claim 1 , wherein the flat tube is formed by extrusion. 
     
     
         5 . A refrigeration cycle apparatus comprising the heat exchanger of  claim 1 .