Surface wettability effect of plain and plasma-sprayed copper-coated surfaces on CHF enhancement during saturated pool boiling of FC-72

摘要

In the current scenario, CHF study is essential for the safe operation of electronics equipment comprising a two-phase heat transfer process. Therefore, the present experimental investigation involves saturated pool boiling and CHF study of FC 72 over a plain stainless steel surface (SS) and microporous copper-coated SS surfaces under atmospheric conditions. Accordingly, three different plasma-sprayed copper-coated surfaces with coating thicknesses of 65 mu m, 105 mu m, and 145 mu m prepared using micro copper particles of size 25-45 mu m. The analysis of the results shows that with an increase in heat flux values, the boiling heat transfer coefficient increases over plain as well as coated surfaces. The plasma-spayed copper-coated surfaces with a coating thickness of 65 mu m and 105 mu m exhibit a higher boiling heat transfer coefficient as than the plain surface. On the other hand, a 145 mu m thick coated surface resulted in a comparable boiling heat transfer coefficient with the plain SS surface. Among the three porous-coated surfaces, the boiling heat transfer coefficient decreases continuously from 65 mu m to 145 mu m of the coated surface. On the contrary, to the observed nucleate boiling behavior, all the porous-coated surfaces show a higher value of CHF than the plain surface, and the CHF value is found to increase continuously from 65 mu m to 145 mu m of the coated surfaces. The enhancement of CHF values was found to be 66.29%, 69.17%, and 77.75% for a coating thickness of 65 mu m, 105 mu m, and 145 mu m, respectively, compared with the plain surface. The porous coating thickness of 65 mu m shows a greater value of heat transfer coefficient than 105 mu m and 145 mu m whereas 145 mu m exhibits a higher value of CHF as than 65 mu m and 105 mu m.