Multifidelity Simulation of Underhood Thermal System for a Bus Engine

This study performs a combined 0-dimensional/3-dimensional modelling ap-
proach to investigate the fluid flow and heat transfer characteristics of a bus
thermal management systems. The 3-dimensional model is deployed to de-
velop new correlations for the heat transfer coefficient (Colburn-j factor) and
the friction factor (Fanning-f factor) at the air-side of the multi-louver ra-
diator and charge-air cooler. The effect of the fan operation is also taken
into account. The existing correlations in the literature developed for cars
where the radiator and charge-air cooler are placed in the front section of
the vehicle exposed to a uniform incoming air flow. While in buses, these
components are placed at the vehicle rear section and in contact with a turbu-
lent and non-uniform air flow, highlighting the need for development of new
Colburn-j factor and the Fanning-f factor for air flow within the louvered fins
in these two components The coefficients developed are incorporated into the
0-dimensional model to predict the thermal characteristics of the bus under-
hood for a range of operating conditions. The 0-dimensional model simulates
the heat interaction of the multiple thermodynamic systems. Thus, a better
understanding of the thermal management is achieved by investigating the energy distribution within the engine compartment and describing the per-
formance of the thermal systems. The 0-dimensional/3-dimensional model is
examined under the peak brake power condition. A coolant mass flow rate of
3.74 kg/s and fans speed of 4000rpm are the most optimum results since the
coolant’s temperature is decreased by 5◦C and the parasitic losses are kept
at minimum.