Self-propelled dropwise condensation on a gradient surface. (November 2017)

• Record Type: Journal Article
• Authors: Deng, Zilong; Zhang, Chengbin; Shen, Chaoqun; Cao, Jianguang; Chen, Yongping
• Is Part Of: International journal of heat and mass transfer. Volume 114(2017)
• Page Start: 419
• Page End: 429
• Publication Date: 2017-11
• Subjects: Condensation -- Droplet -- Simulation -- Surface -- Lattice Boltzmann model; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2017.06.065
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: A model of vapor condensation on a gradient surface is developed and verified. Lattice Boltzmann simulation is used to investigate the condensation behaviors. Simulation reproduces self-propelled dropwise condensation on a gradient surface. Vapor condenses into a thin film firstly and then fractures into droplet nucleation. Abstract: A model of vapor condensation on a solid surface is developed and numerically analyzed using the free-energy lattice Boltzmann method. Based on the model, the condensation phase change on hydrophobic, hydrophilic and gradient surfaces are simulated with a particular focus on the condensation on a gradient surface. The droplet nucleation, growth, deformation, coalescence and motion during the condensation on a gradient surface are investigated. The present simulation reproduces the self-propelled dropwise condensation on a gradient surface, the film condensation on a hydrophilic surface and the conventional dropwise condensation on a hydrophobic surface. The results indicate that the condensed droplets on a gradient surface can be swept in time to provide a favorable condition for the subsequent condensation. On a smooth gradient surface, owing to the unbalanced wetting force, the vapor condenses into a thin film firstly and then fractures into droplet nucleation as the condensation process goes on. The larger wettability gradient results in a larger amplitude oscillation of condensation rate and a slighter variation of surface coverage.