Heat exchanger and air-conditioning apparatus

Abstract

A heat exchanger satisfies Expression (1) below, where the number of the main heat transfer tubes is represented as N 1 , and the number of the sub-heat transfer tubes is represented as N 2 . In this heat exchanger, the main heat exchanger satisfies Expressions (2) and (3) below, while the sub-heat exchanger satisfies Expressions (4) and (5) below. 0.1< N 2 ( N 1 +N 2 )<0.4  (1) 0.03< Ta 1 /Ha 1 <0.3  (2) 0.03< Ta 2 /Ha 2 <0.3  (3) AT 1 <Gr 1 /( G×D 1 (ρ L 1 −ρG 1 )) (1/2) ×( X 1 (1/2) ×ρG 1 (−1/4) +(1− X 1 ) (1/2) ×ρL 1 (−1/4) ) 2   (4) AT 2 <Gr 2 /( G×D 2 (ρ L 2 −ρG 2 )) (1/2) ×( X 2 (1/2) ×ρG 2 (−1/4) +(1− X 2 ) (1/2) ×ρL 2 (−1/4) ) 2   (5)

1 . A heat exchanger comprising:
 a main heat exchanger; and   a sub-heat exchanger connected to the main heat exchanger,   the main heat exchanger including   a plurality of main heat transfer tubes extending in an up-down direction, each of the plurality of main heat transfer tubes having a flow passage inside which refrigerant flows,   a first main header into which one end portion of each of the plurality of main heat transfer tubes is inserted,   main fins provided to the plurality of main heat transfer tubes and helping heat exchange between air and refrigerant flowing inside the plurality of main heat transfer tubes, and   a second main header into which an other end portion of each of the plurality of main heat transfer tubes is inserted, the second main header being opposite to the first main header,   the sub-heat exchanger including   a plurality of sub-heat transfer tubes extending in an up-down direction, each of the plurality of sub-heat transfer tubes having a flow passage inside which refrigerant flows,   sub-fins provided to the plurality of sub-heat transfer tubes and helping heat exchange between air and refrigerant flowing inside the plurality of sub-heat transfer tubes,   a first sub-header into which one end portion of each of the plurality of sub-heat transfer tubes is inserted, and   a second sub-header into which an other end portion of each of the plurality of sub-heat transfer tubes is inserted, the second sub-header being opposite to the first sub-header,   the heat exchanger satisfying Expression (1) below, where   the number of the plurality of main heat transfer tubes is represented as N 1 , and   the number of the plurality of sub-heat transfer tubes is represented as N 2 ,   the heat exchanger satisfying Expressions (2) and (3) below, where   a cross-sectional area of the flow passage of each of the plurality of main heat transfer tubes is represented as Ta 1 ,   a cross-sectional area of the flow passage of each of the plurality of sub-heat transfer tubes is represented as Ta 2 ,   a cross-sectional area of the first main header per each of the plurality of main heat transfer tubes is represented as Ha 1 , and   a cross-sectional area of the first sub-header per each of the plurality of sub-heat transfer tubes is represented as Has,   the heat exchanger satisfying Expressions (4) and (5) below, where   a sum total of cross-sectional areas of the flow passages of the plurality of main heat transfer tubes is represented as AT 2 ,   a sum total of cross-sectional areas of the flow passages of the plurality of sub-heat transfer tubes is represented as AT 2 ,   a flow rate [kG/h] of all refrigerant flowing through the main heat exchanger is represented as Gr 1 ,   a flow rate [kG/h] of all refrigerant flowing through the sub-heat exchanger is represented as Gr 2 ,   a gravitational acceleration [m/s 2 ] is represented as G,   an equivalent diameter [m] of a cross-section of the flow passage of each of the plurality of main heat transfer tubes is represented as D 1 ,   an equivalent diameter [m] of a cross-section of the flow passage of each of the plurality of sub-heat transfer tubes is represented as D 2 ,   a density [kG/m 3 ] of liquid refrigerant flowing in the plurality of main heat transfer tubes is represented as ρL 1 ,   a density [kG/m 3 ] of liquid refrigerant flowing in the plurality of sub-heat transfer tubes is represented as ρL 2 ,   a density [kG/m 3 ] of gas refrigerant flowing in the plurality of main heat transfer tubes is represented as ρG 1 ,   a density [kG/m 3 ] of gas refrigerant flowing in the plurality of sub-heat transfer tubes is represented as ρG 2 ,   a quality [−] of refrigerant flowing in the main heat exchanger is represented as X 1 , and   a quality [−] of refrigerant flowing in the sub-heat exchanger is represented as X 2 .
   [Expression 1] 
   0.1< N   2 ( N   1   +N   2 )<0.4  (1)
 
   [Expression 2] 
   0.03< Ta   1   /Ha   1 <0.3  (2)
 
   [Expression 3] 
   0.03< Ta   2   /Ha   2 <0.3  (3)
 
   [Expression 4] 
     AT   1   <Gr   1 /( G×D   1 (ρ L   1   −ρG   1 )) (1/2) ×( X   1   (1/2)   ×ρG   1   (−1/4) +(1− X   1 ) (1/2)   ×ρL   1   (−1/4) ) 2   (4)
 
   [Expression 5] 
     AT   2   <Gr   2 /( G×D   2 (ρ L   2   −ρG   2 )) (1/2) ×( X   2   (1/2)   ×ρG   2   (−1/4) +(1− X   2 ) (1/2)   ×ρL   2   (−1/4) ) 2   (5)
 
   
     
     
         2 . An air-conditioning apparatus comprising:
 a compressor configured to compress refrigerant;   the heat exchanger of  claim 1 ;   an expansion unit configured to expand refrigerant; and   a heat exchanger configured to operate as a condenser when the heat exchanger of  claim 1  operates as an evaporator, and configured to operate as an evaporator when the heat exchanger of  claim 1  operates as a condenser.