Numerical modelling of conjugate heat transfer in force convective flow environment using a combined boiling model (CBM)

Abstract

Subcooled flow boiling is a crucial heat transfer mechanism in which the fluid temperature exceeds its saturation point, leading to phase change. Computational Fluid Dynamics (CFD) is a powerful tool for investigating such phenomena. However, commonly used CFD wall boiling models, such as the Rensselaer Polytechnic Institute (RPI) model, may under-predict convective heat transfer in flow boiling conditions, do not account for conjugate heat transfer (CHT), and often fail to accurately capture vapour flow behaviour after vapour detachment. This study presents a new model, named the Combined Boiling Model (CBM), which integrates CHT, wall boiling, and flow evaporation/condensation to improve predictive accuracy. Simulation results were compared against experimental data, demonstrating that the CBM accurately predicts heat transfer in channel flows with inlet velocities up to 1 m/s and heat fluxes up to 1.7 × 10⁶ W/m².

Keywords

• Boiling
• Evaporation
• Condensation
• Heat Transfer
• CHT
• CFD