Effect of surface condition on boiling heat transfer from silicon chip with submicron-scale roughness

Boiling heat transfer on treated silicon surfaces was studied. Experiments were conducted to investigate the effects of submicron-scale roughness on the boiling heat transfer at a subcooled condition in FC-72 at the ambient pressure. Two-type of treated silicon surfaces were prepared for boiling surfaces using anodisation with HF (hydrofluoric acid) based electrolyte and DMF (dimethylforamide) based one. The back side of the treated surface was glued to the back side of the other silicon chip on which thin film heaters and thin film temperature sensors were fabricated using conventional MUPs processes with doped polysilicon. The treated chips with submicron-scale roughness which provide many possible nucleation sites showed considerable enhancement in the nucleate boiling heat transfer coefficients compared to the untreated silicon surface. Further, the critical heat flux (CHF) of the treated surfaces increase linearly to the increase in the effective area for boiling.