超临界压力下基于径向热物性分布的碳氢燃料流动换热特性研究

Aiming at the coupling mechanism between the radial thermoproperties distribution of hydrocarbon fuel and the convective heat transfer in the supercritical heated tube, a two-dimensional cooling channel model was established， and the numerical simulation of hydrocarbon fuel flow heat transfer was carried out under the conditions of fuel inlet temperature of 300~400 K and heat flux of 0.60~0.75 MW/m². The results show that the various heat transfer phenomena occurring within the heated tube are closely associated with the radial distribution of the cross-section fluid’s thermoproperties. The maximum value of the non-uniformity coefficient of the radial thermal properties of the fluid appears in the heat transfer deterioration zone at the inlet. The phenomenon of heat transfer enhancement is mainly due to the uniform distribution of the specific heat capacity at constant pressure and the thermal conductivity of the mixture, which increases the heat absorption and accelerates the radial heat transfer. When the radial non-uniform coefficient of the cross-section fluid thermal conductivity is 0, that is, when the direction of the radial variation gradient of the thermal conductivity changes, the heat transfer along the radial direction decreases and the wall temperature begins to increase. At the same time, when the radial non-uniformity coefficient of specific heat capacity at constant pressure is 0, the growth rate of wall temperature slows down. Fuel inlet temperature and wall heat flux have significant effects on the thermoproperties of the mixture in the mainstream zone with low temperature and near the heated wall with high temperature, respectively. Increasing the fuel inlet temperature and heat flux can reduce the extent of heat transfer enhancement and expand the influence of axial flow on heat transfer.