Influence of heat-transfer surface morphology on boiling-heat-transfer performance

In order to explore boiling-heat-transfer performances for different surface morphologies, a boiling model was established via the volume-of-fluid (VOF) method. Four kinds of micron-scale pit and protrusion heat-transfer surfaces were designed, and these surfaces on boiling-heat-transfer performance were explored. Additionally, the temperature, heat-transfer coefficient, phase-volume fraction, and flow-velocity distribution of each heat-exchange surface were used to find an optimal structure. When the heat-transfer surface temperature was lower than 378 K, the truncated-cone-pit and cylindrical-pit structures exhibited the best heat transfer capacity due to shorter nucleation time. With an increase of heat-exchange surface temperature in the cylindrical-pit structure, film boiling occurs because of the small space between the microstructures, and the heat-transfer capacity decreases sharply. The film boiling that occurs in the truncated-cone-pit structure is due to the narrow outlet. When the heat-transfer surface temperature is higher than 378 K, the truncated-cone-protrusion structure shows the highest heat-transfer coefficient and, correspondingly, the lowest heat-transfer surface temperature.