Surface effects on the pool boiling CHF

The influence of the surface of horizontally and vertically oriented ribbon heaters made of Stainless Steel 302 or Steel 1010 on pool boiling CHF in FC-72 or H2O was analysed. The ribbon was 50 mm long, 5 mm high and 76.4 mum thick. Surface treatment was performed with different sandpapers and etching in diluted acid. In the central line average R-a range from 0.02 mum to 1.5 mum, the pool boiling CHF on Stainless Steel 302 ribbon heaters in FC-72 increased from 87.6 to 115.4 kW/m(2) and in H2O it increased from 410.8 to 499.7 kW/m(2), while for Steel 1010 ribbon heaters the CHF incresed in H2O from 309.7 to 443.9 kW/m(2). On an etched heater surface, pool boiling CHF in H2O on both Stainless Steel 302 and Steel 1010 increased by 51 % with respect to a sanded surface with the same R-a. It appears that a multiparametric heating surface characteristic and the surface chemistry parameters need to be included in the study.