Heat exchanger and air-conditioning apparatus

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 N1, and
• the number of the plurality of sub-heat transfer tubes is represented as N2,
• 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 Ta1,
• a cross-sectional area of the flow passage of each of the plurality of sub-heat transfer tubes is represented as Ta2,
• a cross-sectional area of the first main header per each of the plurality of main heat transfer tubes is represented as Ha1, 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 AT2,
• a sum total of cross-sectional areas of the flow passages of the plurality of sub-heat transfer tubes is represented as AT2,
• a flow rate [kG/h] of all refrigerant flowing through the main heat exchanger is represented as Gr1,
• a flow rate [kG/h] of all refrigerant flowing through the sub-heat exchanger is represented as Gr2,
• a gravitational acceleration [m/s2] 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 D1,
• 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 D2,
• a density [kG/m3] of liquid refrigerant flowing in the plurality of main heat transfer tubes is represented as ρL1,
• a density [kG/m3] of liquid refrigerant flowing in the plurality of sub-heat transfer tubes is represented as ρL2,
• a density [kG/m3] of gas refrigerant flowing in the plurality of main heat transfer tubes is represented as ρG1,
• a density [kG/m3] of gas refrigerant flowing in the plurality of sub-heat transfer tubes is represented as ρG2,
• a quality [−] of refrigerant flowing in the main heat exchanger is represented as X1, and
• a quality [−] of refrigerant flowing in the sub-heat exchanger is represented as X2.
• [Expression 1]
• 0.1<N2(N1+N2)<0.4 (1)
• [Expression 2]
• 0.03<Ta1/Ha1<0.3 (2)
• [Expression 3]
• 0.03<Ta2/Ha2<0.3 (3)
• [Expression 4]
• AT1<Gr1/(G×D1(ρL1−ρG1))(1/2)×(X1(1/2)×ρG1(−1/4)+(1−X1)(1/2)×ρL1(−1/4))2 (4)
• [Expression 5]
• AT2<Gr2/(G×D2(ρL2−ρG2))(1/2)×(X2(1/2)×ρG2(−1/4)+(1−X2)(1/2)×ρL2(−1/4))2 (5)