Experimental Study on the Performance of the Cooling System for Outdoor Unit Electronic Module Using Air-Conditioning Condensate

Abstract

Abstract. To address the dual challenges of air-conditioning condensate recovery and high heat flux dissipation from electronic control chips in outdoor units, this study proposed two innovative cooling systems. Experimental investigations were conducted to evaluate the performance of these systems and the evaporation capacity of condensate within the outdoor unit. The first system integrates a water-cooling plate (WCP) heat sink and evaporative cooling pad, while the second adopts a heat pipe heat sink (HPHS) consisting of a base plate, copper mesh fins, and heat pipes. Key operational parameters analyzed include air conditioner operating conditions, compressor frequency, and fan speed. Experiments showed that the average chip temperature reduction of 6.6 °C was achieved at a compressor frequency of 55–90 Hz. The condensate water evaporation capacity was evaluated under ambient temperature ranging 30–42 °C and 35–95% releative humidity (RH), with maximum evaporation rates of 0.24 g/s for the heat pipe-copper mesh and 0.63 g/s for the evaporative cooling pad. Additionally, the WCP system was tested in the summer in two selected regions, yielding an average cooling capacity of 3.68 kW. The impacts of condensate impurities and the urban heat island effect on the WCP system were also examined. A long-term operation test further revealed that when the compressor frequency ranged from 70 to 88 Hz, the chip temperature remained below 50 °C, confirming the system's stability in practical applications. Moreover, complete evaporation of condensate water was achieved with the large cooling pad under outdoor conditions of 35 °C and 52% RH.