Minimum film-boiling quench temperature increase by CuO porous-microstructure coating

Abstract

Increase in the minimum film-boiling quench temperature, T MFB , is achieved with microstructured CuO particles, and attributed to local cooling (fin effect) by the microstructure causing liquid-solid contact. A periodic structure is obtained using electrochemical deposition of 1 lm diameter particles on brass sphere diameter 15 mm forming unit-cell porous cones of average height L ¼ 100 lm and base diameter D ¼ 20 lm. Fin analysis predicts the cone tip cooling to the homogeneous nucleation temperature of water ($330 C), while the base temperature is at 600 C. This causes liquid-solid contact during quenching, and analysis suggests the fin effective thermal conductivity hki and fin characteristic length L 2 /D are key to this liquid-solid contact that influences T MFB .