Coalescence, Spreading, and Rebound of Two Water Droplets with Different Temperatures on a Superhydrophobic Surface

Hao Xu; Chao Chang; Nan Yi; Peng Tao; Chengyi Song; Jianbo Wu; Tao Deng; Wen Shang

doi:10.1021/acsomega.9b01181

Coalescence, Spreading, and Rebound of Two Water Droplets with Different Temperatures on a Superhydrophobic Surface

ACS Omega. 2019 Oct 14;4(18):17615-17622. doi: 10.1021/acsomega.9b01181. eCollection 2019 Oct 29.

Authors

Hao Xu¹, Chao Chang^{1

2}, Nan Yi¹, Peng Tao¹, Chengyi Song¹, Jianbo Wu¹, Tao Deng¹, Wen Shang¹

Affiliations

¹ State Key Laboratory of Metal Matrix Composites, Advanced Energy Materials and Technology Center, School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
² Institute of Marine Engineering and Thermal Science, Marine Engineering College, Dalian Maritime University, Dalian 116026, P. R. China.

Abstract

This paper studied the coalescence, spreading, and rebound of two droplets with different temperatures on a superhydrophobic surface. When the temperature of the impacting droplet was the same as that of the stationary droplet, there was a large deformation of both droplets before the coalescence and the energy dissipation was also large. The coalescence happened at the time close to the maximum spreading. When the temperature of the impacting droplet increased, the deformation of both droplets became smaller before the coalescence and the coalescence happened at or even before the droplets started to spread. The energy dissipation and loss in the later situation is less than those in the previous case. The rebounding characteristics of the merged droplets were also found to be dependent on the temperature. There is an optimum temperature at which the merged droplets can rebound for more times due to the balance of energy loss and also the interaction of the merged droplets with the underlying superhydrophobic substrate. These findings may help further the fundamental understanding of droplet collision on a superhydrophobic surfaces and also offer an alternative strategy to remove droplets from the underlying surfaces for different industrial applications, including condensation heat transfer in steam power plants and phase-change-based thermal management systems.