A computer simulation model to predict the thermal responses of an on-highway heavy duty diesel truck in transient operation was used to study several important cooling system design and operating variables. The truck used in this study was an International Harvester COF-9670 cab-over-chassis vehicle equipped with a McCord radiator, Cummins NTC-350 diesel engine, Kysor fan-clutch and shutter system, aftercooler, and standard cab heater and cooling system components.
Input data from several portions of a Columbus to Bloomington, Indiana route were used from the Vehicle Mission Simulation (VMS) program to determine engine and vehicle operating conditions for the computer simulation model.
The thermostat-fan, thermostat-shutter-fan, and thermostat-winterfront-fan systems were studied. Investigations were conducted for ambient temperatures of -10, 32, 85, and 100°F, full- and half-vehicle load (72,000 and 36,000 lbm Gross Vehicle Weight (GVW)), and alternate routes of operation utilizing recent improvements in the model.
The results show that the thermostat-shutter-fan system provides the best cooling system performance in terms of coolant temperature control, minimization of fan and thermostat operation, and provides adequate cab comfort over the range of vehicle operation and ambient temperatures.