Design and performance optimization of microchannel condensers for electric vehicles

Conventional air conditioning systems for electric vehicle have insufficient performance. Therefore, the structures on both sides of microchannel condensers must be optimized to improve their thermal hydraulic performance and enhance the COP of the air-conditioning system in electric vehicles. Through numerical calculations and experiments, the thermal hydraulic performance of microchannel condensers were evaluated to determine the optimal values of the microchannels number, flat-tube hole aspect ratio, flow passes, and fin pitch. The results obtained using established numerical calculation models have certain reliability with errors within +/- 5.6%. The results reveal that the heat exchange performance of the microchannel condensers could be enhanced by appropriately reducing the fin pitch at certain frontal air velocities. Additionally, this causes a rapid increase in air flow resistance. When the flat-tube hole aspect ratio is 1.15 and the number of flat-tube channels is 10, the microchannel heat exchanger demonstrates optimum thermal hydraulic performance. Experimental results show that the heat exchange capacity of the three- and four-pass microchannel condenser are very close which is 36.5% greater than that of the two-pass microchannel condenser. Meanwhile, the three-pass condenser refrigerant flow resistance is 8.3% lower than that of the four-pass condenser. Therefore, the microchannel condenser with three passes demonstrates the best thermal hydraulic performance.