Visual Observations of Flow and Phase Phenomena in Loop Heat Pipes

Abstract

The Canadian Space Agency is developing loop heat pipe hardware aimed at understanding the thermal performance of two‐phase heat transfer devices and in developing numerical simulation techniques using thermohydraulic mathematical models, to enable development of novel thermal control technologies. This loop heat pipe consists of a cylindrical evaporator, compensation chamber, condenser along with vapor and liquid lines, which can be easily assembled/disassembled for test purposes. This laboratory setup is especially designed to enable the visualization of fluid flow and phase change phenomena. There are transparent windows in the compensation chamber and transparent lines for vapor line, liquid returning line, and sections of condenser that enable the monitoring of the fluid phase and flowing characteristics along the loop. The setup demonstrated typical loop heat pipe performance. Three working fluids (water, acetone and methanol) were used in the characterization of the loop heat pipe. Visual observations have been made at the compensation chamber, vapor line, liquid line, and the condenser.