Numerical simulation of virus inactivation in under-train air duct of high speed train air conditioning systems

Taking SARS-CoV-2 as the target of inactivation, ultraviolet lamps are arranged in the under-train air duct of the CRH2 electric multiple unit air conditioning system. Based on computational fluid dynamics (CFD)， a numerical calculation model of coupled air flow, lamp heating, ultraviolet radiation and particulate radiation dose is developed, and the virus inactivation effects under different lamp arrangements are compared. The results show that the arrangement of ultraviolet lamps can increase the average flow time of particles in the under-train air duct. At the same time, changing the arrangement of the lamps in the under-train air duct can effectively improve the distribution of the radiation field and increase the radiation dose received by particles. Among the four types of lamp arrangements studied, the radiation field in the under-train air duct with wavy distribution (type-D) is more uniform, and the radiation dose received by particles increases significantly, which is much higher than the D90 inactivation standard of the SARS-CoV-2.