MODELING OF A HEAVY-DUTY TRUCK COOLING SY STEM

A transient mathematical model of a heavy duty truck cooling system wa s developped, in order to predict the fan power consumption. It is com bined to a larger computer program, which simulates the global vehicle operating on roads. The model is divided in several parts. In the wat er cooling system, a double Laplace transform is used to integrate the equation of heat and to calculate temperatures and heat transfer alon g the radiator. The heat transfer coefficient is empirically determine d. In the air cooling system, air characteristics were calculated at s everal points of the duct, taking into account the pressure drop (or r ise) of each component - calculated with semi-empirical formulations - and the heat flux of each radiator. The fan power consumption is dete rmined with an empirical correlation based on constructor performance curves. Driven by input variables of vehicle and engine dynamics (engi ne speed, fuel rate, vehicle speed), which are supplied by the vehicle computer program, the cooling system model was tested to verify its a dequation to physical reality.