Multifidelity simulation of underhood thermal system for a bus engine

This study performs a combined 0-dimensional/3-dimensional modelling approach to investigate the fluid flow and heat transfer characteristics of bus thermal management systems. The 3-dimensional model is deployed to develop 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 radiator 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 turbulent and non-uniform air flow, highlighting the need for development of new Colburn-j factor and 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 underhood 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 performance 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 4000 rpm are the most optimum results since the coolant's temperature is decreased by 5 degrees C and the parasitic losses are kept at minimum.

Automated summary

This study uses a combined 0-dimensional/3-dimensional modelling approach to investigate the fluid flow and heat transfer characteristics of bus thermal management systems and develops new correlations for heat transfer coefficient and friction factor. The necessity of developing new correlations for air flow within the components in buses is highlighted, compared to existing correlations developed for cars.