Vapor injection technology for heat-pump air conditioner of electric bus in an extreme environment

In order to solve the problems of a heat pump air conditioner for an electric bus under extreme conditions, such as the large compression ratio, the high discharge temperature, the reduced system performance, the frequent shutdown of the compressor due to the overheat protection, this paper proposes a vapor injection technology with an economizer, and carries out a theoretical analysis of the process to reveal the effect of the vapor injection technology on the performance of the air conditioner. The results show that at ultra-low temperature heating operating conditions, when the compressor speed increases from 2000 rpm to 5000 rpm, the heating capacity of the vapor injection system increases from 16.2% to 22.7%, and the heating performance coefficient increases from 2.8% to 14.2%