Cabin modelling approach in 1D simulation for studying the impact of partial recirculation in warmup for BEV at extreme cold ambient conditions

The inclusion of the cabin in HVAC simulations gained more importance with the introduction of BEV’s. Thermal management and efficiency being in the forefront, exploration for the possible opportunities to reduce the energy consumption for meeting the comfort of passengers gained importance. The energy consumed by the Electric coolant or air heaters for heating the cabin at extreme cold ambient temperatures to deliver similar comfort to that of an ICE version is 2 to 3 times that of the energy required for cooling the cabin in a high ambient condition. Even during the sizing of HVAC system, if traditional method of ambient or fresh air conditions is considered for calculating the requirements, the result is we would require a product which will have unrealistic performance demand. Hence to explore different possibilities for studying the system, usage of recirculation air was considered as one of the options. This paper talks about the approach followed in creating the cabin model in 1D simulation using AMESIM and using it effectively for studying the impact in the performance of the system at various recirculation conditions. The cabin model is discretized into various rows, and the floor part of the model is considered as a separate volume. The model is optimized for both the recirculation air temperature and the cabin air temperature. The recirculation air is then mixed with fresh air according to the required percentage using an air mixture before using it as the inlet condition of the heater core. The model performance is also verified with multiple vehicle test data, proving the robustness in the modelling approach and accuracy in prediction.