Experimental study on effect of surface roughness on heat transfer in boiling

A theoretical and experimental analysis of the heat transfer surface roughness effect on heat exchange has been carried out. It was theoretically proved that smaller temperature beads correspond to greater normalized roughness parameters (e.g., Rsub(max) - the greatest height of surface nonuniformities) at the same heat flux density. Experimental examination of boiling of mercury, amalgams, and water on surfaces with Rsub(max) = 0.18-32 μm has been carried out in order to arrive at more accurate recomendations. The pressures varied from 0.1 to 20x105 Pa, heat transfer surface temperature to max. 670 deg C. The results obtained offer quantitative evaluations of the roughness effect and confirm theoretical concepts