A numerical study of heat transfer for a turbulent flow of supercritical helium

A finite difference method is applied to numerically model heat transfer to turbulent supercritical helium. Three models of turbulence are considered: the mixing length model, the k-model, and the k-epsilon model, and the results obtained with each are compared with available experimental data covering three different cryogenic inflow temperatures and two mass inflow rates. The equations are solved with a marching procedure, and attention is focused on effects near the critical point. The existence of a pseudocritical point, where the specific heat peaks at a specific supercritical pressure, is found to correlate with a peak heat transfer coefficient for low heat flux values. The wall temperature exhibits an abrupt drop at larger heat fluxes in cases when the bulk temperature achieves the pseudocritical value, yielding a sudden rise in the heat transfer coefficient.