Numerical Simulation of Vapor Dropwise Condensation Process and Droplet Growth Mode

Yali Guo, Run Wang, Denghui Zhao, Luyuan Gong () and Shengqiang Shen
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Yali Guo: National Joint Engineering Research Center for Thermal Energy Integration, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China
Run Wang: National Joint Engineering Research Center for Thermal Energy Integration, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China
Denghui Zhao: National Joint Engineering Research Center for Thermal Energy Integration, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China
Luyuan Gong: National Joint Engineering Research Center for Thermal Energy Integration, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China
Shengqiang Shen: National Joint Engineering Research Center for Thermal Energy Integration, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China

Energies, 2023, vol. 16, issue 5, 1-22

Abstract: Compared with film condensation, dropwise condensation based on droplet growth can significantly improve the condensing equipment’s water collection and thermal efficiency in the vapor condensate system. Therefore, as a critical behavior affecting the evolution of dropwise condensation, research on droplet growth is of great significance to further understanding the evolutionary characteristics and heat transfer mechanism of dropwise condensation. In this paper, a model for simulating the entire evolution process of dropwise condensation is improved and constructed, and the evolution process of dropwise condensation with different condensation nucleus densities on the vertical wall is simulated based on certain assumptions. Moreover, parameters such as evolution rate and size contribution are proposed to measure droplet growth’s influence on the evolution process of dropwise condensation. In the simulation, the Cassie model was used to describe the condensation growth of droplets. The neighbor finding algorithm and conservation law are coupled to simulate the coalescence growth process of droplets. Through the comparison of the theoretical model and experimental results, it is indicated that the simulation method in this paper is highly reliable. The simulation results demonstrate that more than 95% of the maximum droplet size of dropwise condensation is derived from coalescence growth, and its growth rate can characterize the evolution rate of dropwise condensation. The evolution rate reveals a linear growth trend with the increase of condensate nucleus density, and the average heat flux shows an increasing trend followed by a decreasing trend, reaching the peak, q average = 30.5 kW·m −2 , at the N S = 5 × 10 9 m −2 . The surfaces with a high coalescence frequency can increase the contribution of the coalescence growth to the maximum droplet size more effectively and, conversely, the contribution of condensation growth is weakened, which is less than 1% at the N S = 7.5 × 10 9 m −2 .

Keywords: dropwise condensation; evolution rate; growth mode; size contribution; contribution proportion (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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