Using Thermoelectric Converters for Loop Heat Pipe Operating Temperature Control

Abstract

This paper describes an experimental study to investigate the effectiveness of using thermoelectric converters (TECs) to control the loop heat pipe (LHP) operating temperature. Tests are conducted on an LHP having two evaporators and two condensers. Each evaporator has its own integral compensation chamber (CC). One TEC is used for each CC. One side of the TEC is attached to the CC, and the other side is connected to the evaporator through a copper thermal strap. A bi-polar power supply is used to provide the power for the operation of each TEC. The bipolar supply automatically changes the direction of the current to the TEC, depending on whether the CC requires heating or cooling, to maintain the CC temperature at the desired set point. When the TEC is cooling the CC, the heat absorbed by the TEC plus the power needed to operate the TEC is dissipated to the evaporator, and is ultimately transmitted to the condenser. When the TEC is heating the CC, the TEC can draw heat from the evaporator to supplement the required control heater power. Test results show that the TEC can control the LHP operating temperature within ±1K of the set point temperature. The control heater power required to heat the CC using TECs is also much less than that of using electrical heaters.