Theoretical investigation on microstructured hybrid surface heat transfer characteristics with Marangoni convection effect
Hamid Saffari, Mohammad Kamali, Ehsan Vatanjoo, Ehsan Aminian
Abstract
The vapor condenses on the surface as a liquid film or distinct droplets, depending on the surface and fluid properties and the environmental conditions. The maximum droplet radius, micro-structure geometry, and Marangoni convection have proved to have a significant impact on the heat transfer characteristics. This paper investigates and compares the effects of different parameters on the heat transfer characteristics of three distinct hybrid surface models. The Marangoni convention effects originating from the temperature gradient are considered in all calculations. The results showed that an optimum maximum droplet radius exists in all three models in which the maximum hybrid heat flux can be obtained. The maximum hybrid heat flux is 133.94 (kW/m2) for the smooth model, 102.34 (kW/m2) for the Wenzel model, and 93.05 (kW/m2) for the Cassie-Baxter model. The results indicated that shorter micropillar heights result in higher complete dropwise and hybrid heat fluxes in the Cassie-Baxter and Wenzel models. The increase in the solid fraction is observed to increase the complete dropwise and hybrid heat fluxes as well.