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Experimental study on evaporation-capillary pumping flow in capillary wick and working fluid system

ABSTRACT
The evaporation-capillary pumping flow of the capillary wick and the working fluid system was experimentally studied in this paper. The capillary wick used in the experiment was fiber, and the working fluid contained water, ethanol and ethanol aqueous solution with water content of 25wt.%, 50wt.% and 75wt.%. The results show that the capillary pumping rate with ethanol as working fluid is between 210.0kg/m2sand 1812.5kg/m2swhen there is no heat load added. When the heating flux is 10616W/m2, 15924W/m2, 21231W/m2, 26539W/m2, the evaporation-capillary pumping rate is102.5kg/m2s, 247.5kg/m2s, 390.0kg/m2s and 530.0kg/m2s, respectively. The higher the heat load power, the greater the evaporation-capillary pumping rate and the higher the final stable temperature. With the increase of heat load power, the time required to reach temperature balance becomes shorter and the temperature fluctuations after reaching temperature equilibrium become larger. The obvious temperature fluctuation has occurred when the heat flux is 26539W/m2. The evaporation capillary pumping rate corresponding to the four different concentrations of ethanol solution in the experiment gradually decreases with the increase of water content. The temperature change processes and the final equilibrium temperatures of the four working fluids are nearly the same. The differences in boiling point of the working fluids do not have much influence here.
KEYWORDS
PAPER SUBMITTED: 2018-09-18
PAPER REVISED: 2019-09-29
PAPER ACCEPTED: 2019-10-26
PUBLISHED ONLINE: 2019-11-17
DOI REFERENCE: https://doi.org/10.2298/TSCI180918413L
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