Experimental Study On Heat Transfer Properties Of Aqueous Methanol Pulsating Heat Pipe

In this paper，a looped pulsating heat pipe was investigated on an experimentalsetup systematically with four working fluids：water,30%aqueous methanol,50%aqueous methanol and anhydrous methanol, and different wall temperature, thermalresistance and their varying trends with different heat loads, inclination angles and fillratios of the pulsating heat pipe were measured．This paper analyzed the heat transferproperties at the start-up stage and stable operating stage.In the start-up stage of aqueous methanol pulsating heat pipe, at50%filling rate,30W heating load and45°inclination angle, the water pulsating heat pipe start-up typeis the temperature smooth transition, while anhydrous methanol and aqueousmethanol are the temperature gradient. But at90°angle, the setup type of water is thetemperature mutant startup mode, while anhydrous methanol and aqueous methanolare still the temperature gradient mode;50%aqueous methanol heat pipe can start upwithin a shortest time and start-up ability is superior to the other three kinds ofworking fluids.At the stable operating stage of aqueous methanol pulsating heat pipe, with20%and50%charging rate, the heating section temperature increase with the increase ofheat loads, and the thermal resistance of four kinds of working fluids first decreaseand then increase with the increase of heat loads.With50%filling rate, the thermal resistance of the four working fluids firstdecrease and then increase with the increasing of the inclination angle; when theinclination angle is45°and90°,at low heating power，the heat transfer performance of50%aqueous methanol pulsating heat pipe is better than the other three workingfluids. At50%charging rate,30W heating load and45°inclination angle, the operatingtemperature and temperature pulsation amplitude of50%aqueous methanol is alwaysinterposed between the absolute alcohol and water, heat transfer stability is better thanwater and the pulsating frequent is lower than anhydrous methanol; but at90°inclination angle, temperature pulsation amplitude of50%aqueous methanol is higherthan water and methanol, while operating temperature is interposed between the methanol and water.