CFD Homogeneous Mixing Flow Modelling to Simulate Subcooled Nucleate Boiling Flow

The homogeneous mixing flow modelling approach has been incorporated in a CFD framework to study subcooled nucleate boiling heat transfer that may occur in IC engine cooling passages. The approach is based on the assumption that vapour bubbles are small and perfectly mixed with the liquid phase (bubbly boiling flow pattern). A void faction equation has been introduced into the single phase CFD solver to describe the concentration of the vapour phase. Superheated wall heat transfer, fluid evaporation and condensation mass transfer are described by sub-models. Primary validations of the method have been conducted using channel boiling flow data from the literature over a range of flow speed, liquid subcooling and wall superheat conditions. The predicted wall heat flux and vapour concentration distributions are in satisfactory agreement with the experimental measurements. The engineering application is demonstrated by the CFD analysis of an engine cooling passage flow involving local boiling.