Heat transfer tests under forced convection conditions with high wettable heater surface

Under forced convection and atmospheric pressure conditions, heat transfer tests were performed using the annulus channel of a heater rod with highly wettable surface. Improvement of boiling heat transfer requires that the cooling liquid can contact the heating surface, or a high-wettability heating surface, even if a vapor bubble layer is generated on the surface. From this point of view, high-wettable heating surface was studied. As oxide semiconductor-coated materials are highly-wettable, we made a TiO2 coated heater rod. TiO2 coated surface has a high-wettability, in terms of contact angle and Leidenfrost temperature. The boiling curve was measured with and without TiO coated surface. The results showed difference between with and without TiO2 coating. TiO2 coating rod showed lower boiling onset heat flux, wider nucleate boiling region and higher critical heat flux than without coating. In summary, high wettablity heater surface produced higher boiling heat transfer characteristics under forced convection conditions. (author)