Experimental investigation on temperature oscillation of loop heat pipes

The phenomenon of temperature oscillation in loop heat pipes was described and explained. Test results indicate that temperature oscillation frequently occurred at very low and very high heat loads. At low start-up heat loads evaporation inside the primary wick was easy to occur when the evaporator, including vapor grooves and evaporator core, were flooded with liquid. Evaporation inside the wick will lead to the temperature oscillation at the condenser inlet. Start-ups with temperature oscillation at the condenser inlet will shift the steady state operating temperatures higher than normal. While at high heat loads, vapor can not be condensed absolutely in condenser for its limit ability to reject heat and temperature oscillation will occur at the condenser outlet, which can be avoided by increasing the working fluid charge mass.