Thermal management in automotive applications

With advances in automobiles -- particularly in the electronics fostering more functionality -- the heat dissipation is increasing at a rapid rate and hence thermal management is becoming more of a driving force than ever. Thermal management issues for trucks are even more daunting than for cars. While automobiles tend to be largely mass-produced, large trucks are typically custom designed.

In fact, successive trucks leaving an assembly line typically will have different engines and different cooling system requirements, making design and optimization of truck thermal management systems even more difficult. Engine manufacturers, truck manufacturers and equipment suppliers each have a role to play. Given that there are so many components in a car or truck today, an increasing number of studies are underway to boost their performance.

Such activities involve fan systems, particularly in heavy trucks. Fan power requirements in large trucks can be 35 to 50 kW. This high energy consumption can have a dramatic effect on fuel consumption. In these circumstances, axial fans are directly driven by the engine and an optimized fan shroud is used with a viscous clutch and a thermostat to control the fan. The under-hood air flow management is of utmost importance, because all the heat generated in the automobile components has to be removed by the motion of air in the compartment.

The automotive engine control module (ECM) is one component in the car that is exposed to extreme temperatures around 105°C to 125°C. The power dissipation of these modules is typically around 10-30 watts. The components on the ECM are generally designed to withstand 105°C. The case to ambient thermal resistance of some of these components is approximately 1-3°C/W.

The design of more-aerodynamic body shapes results in less available grilled area and under-hood space. This lack of space for airflow requires that the fan system create more pressure and that the overall system include more efficient heat exchangers. With a reduction of external aerodynamic drag, the contribution of under hood air flow has been shown to be significant.

This article, written by the engineers at Advanced Thermal Solutions, Inc., Norwood, MA, explores this topic further and looks at some thermal modeling techniques and approaches. (ATS is an engineering and manufacturing company supplying complete thermal and mechanical solutions, from analysis and testing to final production.)

To read the article, click here.