Influence of surface roughness on pool boiling heat transfer

Experimental study of pool boiling heat transfer from the rough surface at pressure 1 bar, 5 bar and 10 bar is presented. Experiments are carried on 20 mm diameter copper sample at saturated condition of distilled water. Unidirectional scratches are made by different grit sandpaper. The surface roughness value R_a is varied from 0.106 μm to 4.03 μm. The effect of R_a on heat transfer at different pressure is reported. The variation in heat transfer coefficient with the heat flux for samples of different R_a is also examined. The predicted critical heat flux (CHF) by Kim's model is found to in good agreement with present experimental values with mean absolute error of 12.06%. (paper)