Thermal Modeling of Electronics Inside a Truck Cabin

Abstract

Electronic Control Units(ECUs) are critical components in trucks, which are required to be operated within specific temperature ranges to minimize its failure rates. Some of the ECUs have integrated safety functions, and failure of these could result in the breakdown of the vehicle. These are often mounted underneath the Instrumentation Panel(IP), a confined space that also houses other heat sources, complicating their thermal management. Therefore, to understand the thermal behavior of ECUs under various conditions, Computational Fluid Dynamics(CFD) was used. The CFD model was used to study the effects of factors such as ambient temperature, recirculation, and vehicle velocity on the ECU’s thermal performance. A Proportional-Integral(PI) controller was modeled to regulate the air temperature through the HVAC(Heating, Ventilation, and Air Conditioning) ducts to maintain the cabin temperature at 22◦C. To prevent oscillations while solving, the temperature of air through the HVAC was updated every 50 iterations. Recirculation, which enhances the mixing of air inside the IP, was shown to decrease the temperature of the ECU. The extent of this temperature reduction was found to be influenced by the ambient temperature. Based on the understanding of the operation of the HVAC system, it was concluded that the cooling performance of the ECU is critical in cold ambient conditions. It was observed that at an ambient temperature of 0◦C, increasing the recirculation fraction from 0 to 0.8 reduced the ECU’s maximum temperature by approximately 7◦C. Based on the study’s findings, several cooling strategies were proposed to improve the thermal management of ECUs. Utilizing the existing fan of the ECU to enhance the mixing of air within the IP was shown to reduce the ECU’s temperature by around 5 ◦C. While, incorporating an additional fan provided an even greater reduction, lowering the temperature by approximately 8◦C.