Convective heat transfer in the motion of a medium under the conditions of supercritical pressures

Abstract

located at the distance x = 60d from the inlet to the tube. Clearly, the character of change in the curve on the section AB is the same as in normal convective heat transfer. At the point B, the temperature of the cooled surface of the tube wall approaches the pseudocritical temperature t m (corresponding to the maximum specific heat C P ) of the considered liquid and here additional sound effects originate — heat transfer involves oscillations of the pressure P and the temperature t w . Probably, on condition that t w t m , a sharp change in thermophysical parameters (especially in C P and P) of the liquid in the near-wall region gives rise to additional effects and enhances heat exchange on the section BC of this dependence. After the point C, with increase in q, t w rises by a linear law, resulting in the formation of the section CD. In our opinion, the rise in the temperature t w and, correspondingly, its constancy or a certain decrease in the heat-transfer coefficient are also linked with the decrease in C P on condition that t w > t m . At large values of q and t w , this temperature initially sharply decreases and thereafter slowly increases as the