Study of convective heat transfer at supercritical pressures

Abstract

The article presents the results of studies of the nature of changes in the graph of the wall temperature dependence on the heat flux density, which established that regardless of the position of the pipe and the direction of fluid flow at supercritical pressures and tc ~ tm, a mode with improved heat transfer occurs. The onset of improved heat exchange when the temperature of the inner wall surface reaches the pseudocritical temperature of the studied liquid (n-heptane) undoubtedly indicates the influence of changes in thermophysical parameters on the heat transfer process. Under these conditions, all thermophysical properties, changing sharply, obtain their extreme values. Moreover, with distance from the critical pressure, as shown by the results of studies of thermophysical properties, and in the pseudocritical tempera­ture region, the rate of change of physical parameters noticeably weakens, which should have a certain effect on heat transfer.