A methodology for indoor testing of solar radiation impact on vehicle cabin temperature

Abstract

Air conditioning systems for automotive applications are always striving to attain optimal and effective solutions in order to fulfil diverse needs. Yet, to thoroughly evaluate their system performance, it is essential to account for the influence of solar irradiance on the overall thermal dynamic within vehicle cabin. This study presents an approach to simulate the impact of solar radiation on vehicle cabin thermal behaviour using electric blankets as a practical and cost-effective means to replicate solar effects. The methodology combines controlled experimental tests in a climatic chamber with outdoor tests under natural solar irradiance and ambient conditions. A thermal model of the cabin is calibrated and validated using the climatic chamber experiments, demonstrating maximum errors not exceeding 3.5 °C and mean absolute errors (MAEs) below 1.86 °C, showcasing the model's high precision. Based on the results obtained from the model, an exponential function was derived that links the vehicle cabin temperature to solar irradiance. Finally, a heating function is defined, which allows estimating the temperature profile of the electric blankets based on the irradiance values, obtaining results very similar to those of the model, with a coefficient of determination of 0.9486. This will allow to accurately predict and control the internal temperature of a vehicle cabin under varying solar irradiance levels.