Heat exchanger and air conditioner

Abstract

A heat exchanger for an air conditioner for which a zeotropic refrigerant mixture is used is obtained, and the heat exchanger, when used as an evaporator, enables reduction of the amount of required refrigerant without deteriorating the heat transfer performance. The heat exchanger includes: a plurality of fins stacked together at predetermined intervals therebetween; first heat transfer pipes which extend through the plurality of fins, in which a heat medium flows, and which have a plurality of grooves in the inner surface of the pipes; and second heat transfer pipes extending through the plurality of fins, having one end connected to one end of the first heat transfer pipes to form one heat medium flow path, being smaller in pipe diameter than the first heat transfer pipes, and having an inner surface shape providing a pressure loss per unit length smaller than that of the first heat transfer pipes.

1 . A heat exchanger comprising:
 a first heat transfer pipe in which a heat medium flows and which has a plurality of grooves formed in an inner surface of the first heat transfer pipe; and   a second heat transfer pipe having one end connected to one end of the first heat transfer pipe to form one heat medium flow path, the second heat transfer pipe being smaller in pipe diameter than the first heat transfer pipe, and having an inner surface shape providing a pressure loss per unit length smaller than that of the first heat transfer pipe.   
     
     
         2 . The heat exchanger according to  claim 1 , wherein
 when the heat exchanger acts as an evaporator, another end of the second heat transfer pipe is an entrance for the heat medium, and   when the heat exchanger acts as a condenser, another end of the first heat transfer pipe is an entrance for the heat medium.   
     
     
         3 . The heat exchanger according to  claim 2 , wherein the heat medium is a zeotropic refrigerant mixture. 
     
     
         4 . The heat exchanger according to  claim 3 , wherein the second heat transfer pipe has a length of less than or equal to 25% of a length of the heat medium flow path. 
     
     
         5 . The heat exchanger according to  claim 1 , comprising a first heat exchanger portion formed by the first heat transfer pipe, and a second heat exchanger portion formed by the second heat transfer pipe and separate from the first heat exchanger portion. 
     
     
         6 . An air conditioner comprising the heat exchanger according to  claim 1 , the heat exchanger being used either as an outdoor heat exchanger or an indoor heat exchanger.