Heat Transfer in a Supercritical-Pressure Liquid Under Pulse Heating: Model for a Wide Range of Pressures and Temperatures

This study is devoted to extending our insights into peculiarities of the heat conduction of supercritical (SC) fluids in the course of rapid (due to the high heat generation power in the wire probe) transition of compressed fluid to the SC state along the isobar. The comparison is performed with respect to the thermal picture known from quasi-static experiments, where molecular thermal conductivity is usually masked by convection. The task was to construct a physical model explaining the experimental feature discovered in short-term experiments, namely, the threshold increases in the thermal resistance of the fluid boundary layer when crossing the vicinity of the critical/pseudocritical temperature. Its novelty is based on covering the range of significant deviations of the SC-parameters, namely, pressure (in statics, up to 6 p/p_c) and temperature (in pulse, up to 1.4 T/T_c), from the corresponding critical values (p_c, T_c). The model is verified by comparing its results with the data of a pulse experiment using two essentially different trajectories of penetration into the region of SC-temperatures. The developed model draws attention to potential hazards accompanying heat transfer to SC-fluids in processes with powerful heat generation, typical of a number of modern devices.