Simulation of mobile air-conditioning energy in electrified and conventional vehicles

The vehicle's heating, ventilation, and air-conditioning systems (or Mobile Air-Conditioning systems, MAC), are the most power-consuming auxiliaries, affecting the vehicle's power consumption in all powertrains. MAC power consumption reduces the electric range in electrified vehicles and increases the CO 2 emissions in internal combustion engine vehicles. The MAC consumption assessment is crucial for the decarbonisation of the transport sector. Prediction of MAC energy using simulation models optimizes this assessment, reducing the testing burden, and allowing further analysis of varying exterior conditions and component efficiencies. This paper proposes a thermal model for a vehicle MAC system to estimate the cabin temperature and MAC energy consumption during a WLTC. The A/C compressor power demand is simulated through the refrigerant's semi-Ideal Vapour-Compression Cycle. The model considered a Proportional-Integral-Derivative (PID) controller to regulate the refrigerant mass flow rate. A stepwise validation was done with literature, wind tunnel tests, and chassis-dyno WLTP tests in a climatic cell. Theoretical heat transfer coefficients are obtained. The model accurately predicted the MAC energy. For an external temperature of 35 °C, MAC consumed around 950 Wh for BEVs, 790 Wh for the ICEV, and 760 Wh and 260 for the tested PHEVs in CD and CS modes, respectively, to reach a comfort temperature during a WLTC. The corresponding CO 2 equivalent emissions for cooling are around 9.7, 36, 7.8, and 13.9, gCO 2 eq/km, respectively. Apart from the external temperature, the initial cabin temperature was an influencing parameter for MAC energy, as well as the seats masses and the PID controller gains. Cabin size showed negligible changes in MAC consumption.