Numerical Analysis of Thermal Systems of a Bus Engine

Vehicle thermal management systems have been a critical part of improving vehicle fuel economy, as more than 50% of fuel energy is going to heat. Thermal systems are very complex in terms of thermo-fluid analysis due to the different shaped and size of the components, which make experimental testing challenging. Thus, computer aided engineering (CAE) tools are extensively used to accurately and efficiently predict the performance of thermal systems. Both low-order modelling and 3-dimensional computational fluid dynamics (CFD) simulation methods have been used to analyse the thermal management systems. However, the first method has low accuracy and the latter one has a significant time cost. Creating an integrated low-order/3D model can keep the benefits of both approaches. The aim of this study is the development of a multi-fidelity model, which investigates the details of the heat transfer characteristics and analyses the energy flow in a bus engine. A MATLAB based low-order (0D) model and 3D CFD models using FLUENT have been developed. The 0D model considers heat transfer aspects and thermodynamic laws of all the under-hood thermal systems. As the engine is placed at the rear of the bus, the heat and fluid flow features is difficult to be estimated using 0D model. Through the CFD simulations the heat transfer coefficient of radiator and charge-air cooler is calculated and fed to the low-order model.