1D-3D Dynamic Characteristics and Control Method of a CO₂ Heat Pump Air Conditioning System for Vehicles

A transcritical CO₂ heat-pump air-conditioning system has effective heating performance at low temperatures, and the variation of dynamic parameters during operation significantly affects the thermal comfort inside the passenger cabin. To study the comfort of the passenger compartment and the coupling law of the dynamic changes in the parameters of the transcritical CO₂ heat-pump air-conditioning system, a joint simulation model was built based on the one-dimensional simulation software GT-Suite and the three-dimensional computational fluid dynamics (CFD) software STAR-CCM+. The three-dimensional cabin model can provide accurate real-time state parameters of the supply and return air for a one-dimensional simulation system of heat-pump air conditioners. The results show that the temperature distribution of the thermal environment of the passenger compartment is relatively non-uniform, necessitating the application of the weighted predicted mean vote (PMV) to evaluate this non-uniformity. In a multi-PID control transcritical CO₂ automobile heat pump air conditioning system, a control method based on the weighted PMV comfort model can maintain the regulation and stability of the system′s target parameters. Under ambient temperature conditions of 43 ℃ in cooling mode, the control method can reduce the compressor′s power consumption by 9.4%. At an ambient temperature of -10 ℃ in heating mode, this method can reduce compressor′s the power consumption by 17.9%. This control method can reduce the power consumption of the system compressor while satisfying comfort requirements, constituting a highly efficient energy-saving strategy.