Modelling, Simulation, and Experimental Validation of a Thermal Cabin Model of an Electric Minibus

In response to the urgent need for decarbonising the transport sector, this paper analyses the thermal performance of a battery electric minibus under cold ambient conditions. Thermal simulation models of the vehicle cabin and its electric heating circuits for both driver and passenger areas were developed using Modelica and validated with measurement data at -7 degrees C and 0 degrees C. The model showed good agreement with the measurements, with cabin temperature deviations within +/- 1.6 K and heating power deviations below 6%. Results show that the existing electric-only heating system is, in the automatic heating mode selected, insufficient to reach the target cabin temperature of 23 degrees C, as the optional fuel-powered heater was omitted to ensure fully zero-emission operation. To address this, an extended heating system with an additional heat exchanger was implemented in the simulation, which improved the overall cabin temperature level and also its spatial variation. However, it also increased the heating power demand by 43% at -7 degrees C (from 4.8 kW to 6.8 kW) and by 17% at 0 degrees C (from 4.8 kW to 5.6 kW). An additional heat loss analysis revealed that approx. 65-75% of all thermal losses occur through the window areas. Future improvements should therefore focus on optimising the heating strategy and enhancing cabin and heating system insulation to reduce energy demand while maintaining or even improving passenger comfort.