Enhanced evaporation heat transfer in triangular grooves covered with a thin fine porous layer

Evaporation heat transfer in a triangular groove is enhanced by a thin fine porous layer on the groove surface. This not only improves the capillary force but also extends the evaporating surface with high heat transfer performance. The enhancement mechanism is explained and an analytical model is developed to predict evaporation heat transfer performance in a triangular groove formed by trapezoidal fins covered by a thin fine porous layer. The total heat transfer coefficient decreases with increasing liquid meniscus radii, increases with increasing of the half groove angle and the half width of the fin top surface. With receding of the liquid meniscus in the groove covered by a thin porous layer, the evaporation heat transfer performance is improved significantly. A comparison between evaporation heat transfer in triangular grooves with and without a thin porous layer, at the same conditions, shows the former is much better than the latter although the latter has a small area with a heat transfer coefficient as high as 10(8) Wm(-2) K-1. In the calculation range, evaporation heat transfer in the groove covered by a thin porous layer is three to six times higher than that in the groove without a porous layer. (C) 2001 Elsevier Science Ltd. All rights reserved.