Discussion on predicament and causes of heat rejection and ventilation systems in subway stations

The ability to control the operating thermal environment of the condensers of train air conditioning units is an important indicator to measure the performance of the heat rejection system in the rail area of subway stations, but the existing heat rejection and ventilation system objectively has problems such as poor heat rejection effect, high energy consumption, difficult air duct commissioning, long construction period, and potential safety hazards. Through the actual measurement and investigation of the operating status of the heat rejection system of different stations, it is found that the temperature control effect of the heat rejection system is not obvious, the air volume distribution is uneven, and the necessity of setting up the heat rejection system in different subway environments is different. Furthermore, CFD calculation and comparative analysis of the thermal environment and heat exhaust efficiency under the typical air volume and target air volume of the exhaust air outlets are further carried out, and the results show that the uneven distribution of the air volume of the exhaust air outlets is the main reason affecting the performance of the heat rejection system. When the corresponding exhaust air volume of each condenser reaches 2.5 m3/s, the heat exhaust efficiency exceeds 55% and the heat-air volume ratio reaches 16.7 J/m3, and the systems ability to control the thermal environment of the rail area is significantly improved.