Thermal Management during Hot Shutdown in Off Road Vehicles

Thermal management in off road vehicles is critical because it directly or indirectly affects engine performance, fuel economy, safety, and emission. With the introduction of stringent exhaust emission norms such as the EU stage V and EPA Final Tier 4, modern engines use a Diesel Particulate Filter (DPF) to trap the soot particles present in the exhaust gases. These soot particles are burned using a process called regeneration where skin temperature of DPF increases beyond 400 °C. Situation becomes more worst when the vehicle is shutdown just after the regeneration, where the coolant fan is off and there is no active airflow. Hot air gets trapped and start increasing under hood temperature, affecting the performance of other sub systems like air intake, electrical components, aftertreatment sensors etc. There are several ways to manage this heat load. Normally the heat built up in the under-hood compartment escape to the environment by two paths - convection and radiation. This convective and radiated heat load must be guided smartly to allow it escape and safeguard all the critical components. This paper proposes different techniques to do so and effectively manage thermal load during vehicle hot shutdown condition. The work described in this paper are outcomes and learnings captured during various ongoing live projects. All the necessary testings were conducted in house.