Subcooled Flow Boiling in High Power Density Internal Combustion Engines II: Numerical Modeling

Results from a thermal survey measurement campaign on a four-cylinder Volvo engine was presented in Part I of this article. The focus was predominantly on heat transfer in the engine coolant jacket. This part presents numerical modeling focused specifically on the coolant flow and associated heat transfer in the coolant jacket using computational fluid dynamics (CFD), as a part of a high-resolution complete engine 3D conjugate heat transfer (CHT) model. With local nucleate boiling being an indispensable phenomenon in high power density engines, a dedicated boiling model is essential and is to be used in conjunction with CFD while analyzing heat transfer in the coolant jacket. This article validates a new boiling model with data obtained from the extensive thermal survey measurements, presented in Part I. The new model includes a parameter, based on vapor bubble interactions, that serves as an indication of the transition from beneficial nucleate boiling to high-risk transition and film boiling regimes. This parameter might be used to assess the robustness of new engine designs. The advantages and limitations of the new boiling model are presented and are discussed in detail.