Loop thermosyphons with porous coatings

Abstract

Abstract The aim of this work is to experimentally evaluate the heat exchange of evaporation and condensation inside a new annular thermosyphon with horizontally located zones of evaporation and condensation, which are interconnected by a vapor line and a condensate line. The mini-tube of the liquid line is introduced coaxially into the cylindrical evaporator with a porous coating, thus an annular channel is formed between the tube and the porous coating of the evaporator. The purpose of this study is to determine the thermal resistance of the device and its components, as well as the temperature field along the thermosyphon. The considered thermosyphon guarantees a shorter start-up time, lowers the temperature of the evaporator walls, has a small temperature hysteresis with an increase/decrease in the transferred heat flux, and suppresses temperature pulsations inside an evaporator. The 130 mm long evaporator is made of copper tube (d out = 12 mm, d in = 10 mm). The wick is obtained by sintering copper powder. The working fluids R245fa and R600 were used. The thermal resistance of thermosyphon does not exceed 0.5 K/W, and of the evaporator 0.1–0.05 K/W).