In this study

a heat pump air conditioning system with waste heat recovery was developed based on vapor injection

and the performance was investigated experimentally. The study aimed to address the problem of heating capacity attenuation of heat pump air conditioning systems at low temperatures in winter

through the optimization of heat exchanger design. The experimental results show that the quasi two-stage compression heat pump air conditioner for electric buses exhibits good heating performance at low temperatures. Compared with the same working conditions without waste heat recovery

the heating capacity and coefficient of performance (COP) of the system are improved by 33.15% and 9.94%

respectively

where the ambient temperature is -20 °C

the interior temperature is 20 °C

and the residual heat is 1.8 kW. Compared with the single-stage compression system without battery cooling

the cooling capacity and COP of the optimized electric bus heat pump air conditioning system are increased by 4.58% and 3.72%

respectively

where the ambient temperature is 35 °C

the interior temperature is 27 °C

and the cooling capacity of the battery is 2.0 kW.