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Truck underhood thermal management has become a critical design parameter to meet the increasingly stringent U.S. federal EPA (Environmental Protection Agency) diesel emissions standards. Both heat exchanger modules and vehicle design details have significant impact on the cooling performance. This paper introduces an integrated numerical modeling approach utilizing one way coupled solution combining 3-dimensional finite volume computational fluid dynamics (CFD) method and 1-dimensional simplified system model to simulate full complicated airflow and heat transfer activities. The results are validated against experimental data based on some selected actual vehicle operating conditions for two designs configurations including a new and improved cooling module design.

Due to the stopping distance disparity between heavy trucks and passenger cars, a proposed amendment to FMVSS 121 (Federal Motor Vehicle Safety Standards) will require heavy truck manufacturers to reduce truck-tractor stopping distances. A typical FMVSS 121 stopping distance test takes two to three weeks to complete. It is not practical or cost effective to test all brake, tire, wheel base, and suspension combinations. The ABS (anti-lock brake system) controller also contributes greatly to the complexities of the brake system. A new method has been developed by Navistar, Inc. utilizing extensive computer simulation to study the parameters that affect stopping distance. The simulation model utilizes both real-time HIL (hardware-in-the-loop) and SIL (software-in-the-loop) simulation technologies. The ABS ECU (Electronic Control Unit) was coupled in the simulation through HIL.