Calculation model for convective heat transfer of supercritical fluids by low Reynolds number k-ε model

Based on the boundary layer theory, a new simple numerical model is proposed by taking into account the effect of variable physical properties. Numerical simulations are carried out to investigate the turbulent convective heat transfer of water in tubes at the supercritical pressure(SCP). The comparison of the simulation with experiment data shows that the proposed model gives correct results about the effects of pressure, mass flux and wall heat flux on the heat transfer for variable-property flow at the SCP and saves considerable computation time. Two low Reynolds number k-ε turbulence models by Jones and Launder (JL) to predict heat transfer of water at the SCP are evaluated. The JL1 model (c₁=1.55)agrees well with the constant-property flow but greatly underestimates the heat transfer coefficient under the SCP condition. The JL2 model (c₁=1.45)significantly overestimates the heat transfer coefficient for the constant-property flow, but it exhibits a good prediction in a wide range of parameters under the SCP condition.