The application of microchannel heat exchanger is becoming more and more widely. The application of microchannel heat exchanger (MCHX) on domestic air conditioning system was investigated experimentally. The results show that: (1) when only the indoor heat exchanger was changed into the microchannel heat exchanger

the system had the best performance when the fin pitch of the indoor MCHX was 1.4mm. The charge of refrigerant for the system reduced 15.9%. Meanwhile

the cooling capacity of the new system was 1% lower than the original system while the COP was 2.2% higher; when it worked in heating mode

the heating capacity of the new system was 3.9% higher than the original one while the COP was 11.2% higher than the original one; (2)when all the heat exchangers were changed into the microchannel heat exchangers

the charge of refrigerant for the system was reduced 54%. Meanwhile

the cooling capacity of the new system was 0.8% higher while the COP was 5.2% higher than the original one in refrigerating mode; when the refrigerant was changed into R290

the best refrigerant charge for the new system was 500 g.