Objective The air conditioning/ventilation system in metro equipment rooms, such as 0.4 kV switchgear room, is prone to energy waste. The thermal environment in the equipment rooms not only directly affects the stable operation of equipment such as traction substations, but also causes the ventilation energy consumption of the secondary ventilation system in metro stations. In summer, the air conditioning system ensures the internal thermal environment of the equipment rooms. However, in winter, only ventilation is operated replacing the air conditioning, which leads to excessively low indoor temperatures during certain periods. Therefore, it is necessary to conduct on-site measurement and analysis of the winter thermal environment in 0.4 kV switchgear rooms.

Method On-site measurements of the winter thermal environment in the 0.4 kV switchgear room at Xi'an Metro North Station are conducted, and data are collected including the indoor vertical gradient temperature, supply and return air temperature, air volume, and surface temperature of electrical equipment. A numerical simulation method is adopted to analyze the problems existing in the winter thermal environment of the 0.4 kV switchgear room, and then an optimization scheme for air supply volume and the layout of supply/return air ducts is proposed. The optimization results are analyzed with parameters such as the temperature non-uniformity coefficient.

Result & Conclusion  The on-site measurement results show that there is a significant difference between the actual air volume and design value of air outlets in the 0.4 kV switchgear room, and the supply/return air paths are blocked by switchgears, resulting in unreasonable air distribution. A comparison between the optimized scheme and the original one shows that the optimized air distribution reduces heat accumulation; the temperature non-uniformity coefficient is reduced from 0.037 to 0.031, something like a decrease of 16.2%.