Owing to the limited amount of test data available for flow coefficient correlation fitting, there is a large deviation when applying the correlation formula to the flow coefficient calculation of valves with different diameters. To solve this problem, the flow characteristics of an electronic expansion valve were studied experimentally. The experimental results indicated that the valve diameter, valve opening, and subcooling were the main factors affecting the flow coefficient of the electronic expansion valve. The flow coefficient decreased with an increase in the valve opening. The flow coefficient of a valve with a large diameter (DPF2.0) was greater than that of a valve with a small diameter (DPF1.65) under the same opening degree, and the flow coefficient increased with the subcooling degree. A correlation formula for the flow coefficient that considered subcooling degree T_sub and flow area A was fitted using the experimental data, and the relative deviation was calculated to be within ±5% when using this fitting correlation formula.

This study investigated a liquid-cooled charging-cable cooling system for the high-power DC fast charger of electric vehicles. This system utilized perfluoro as the liquid coolant and a serpentine microchannel heat exchanger as the radiator. A mathematical model of the microchannel heat exchanger of this liquid-cooled charging-cable cooling system was established using the ε-NTU and distributed parameter methods. This model was validated through experiments, which demonstrated good consistency between the calculated values and experimental results. By optimizing the flows on both sides of the heat exchanger, along with its structure and configuration, the heat exchange performance was effectively improved while reducing the power consumption. The system employed a parallel arrangement of 28 rows of tubes, which resulted in a temperature reduction of 1.81-2.49 ℃ for the coolant at the gun head and a maximum temperature decrease of 3.51-6.44 ℃ for the charging cable. The results of this study provide valuable insight into the design of the heat exchangers used in liquid-cooled charging-cable cooling systems.