Heat transfer performance of pulsating heat pipe with water-ethanol mixed working fluid.

The heat transfer performance of a closed-loop pulsating heat pipe (PHP) with water-ethanol mixtures was studied by experiments. The heat transfer performance with water-ethanol volume ratio of 13:1, 2:1, 1:1, 1:2, 1:13 were compared with pure water and ethanol working fluids at the same filling ratio of 45% to 70% and heat inputs of 10W to 100W. Experimental results indicated that, at lower filling ratio, the thermal resistance of water-ethanol PHP is smaller than pure water and ethanol PHPs; and at higher filling ratio, the heat transfer performance is generally better, and the heat transfer performance of water-ethanol PHP is almost the same as ethanol PHP. It can be deduced that, the heat transfer performance of water-ethanol PHP depended on the filling ratio and the volume ratio, which may be related to vapour-liquid balance, physical properties and the concentration gradient in both gas and liquid phases.