Dropwise condensation heat transfer process optimisation on superhydrophobic surfaces using a multi-disciplinary approach

Khatir, Zinedine and Kubiak, K.J. and Jimack, P.K. and Mathia, T.G. (2016) Dropwise condensation heat transfer process optimisation on superhydrophobic surfaces using a multi-disciplinary approach. Applied Thermal Engineering, 106 (5/8/16). pp. 1337-1344. ISSN 1359-4311

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Abstract

Dropwise condensation has superior heat transfer efficiency than filmwise condensation; however condensate evacuation from the surface still remains a significant technological challenge. The process of droplets jumping, against adhesive forces, from a solid surface upon coalescence has been studied using both experimental and Computational Fluid Dynamics (CFD) analysis. Both Lattice Boltzmann (LBM) and Volume of Fluid (VOF) methods have been used to evaluate different kinematic conditions of coalescence inducing a jump velocity. In this paper, an optimisation framework for superhydrophobic surface designs is presented which uses experimentally verified high fidelity CFD analyses to identify optimal combinations of design features which maximise desirable characteristics such as the vertical velocity of the merged jumping droplet from the surface and energy efficiency. A Radial Basis Function (RBF)-based surrogate modelling approach using Design of Experiment (DOE) technique was used to establish near-optimal initial process parameters around which to focus the study. This multidisciplinary approach allows us to evaluate the jumping phenomenon for superhydrophobic surfaces for which several input parameters may be varied, so as to improve the heat transfer exchange rate on the surface during condensation. Reliable conditions were found to occur for droplets within initial radius range of r = 20–40 μm and static contact angle θs ∼ 160°. Moreover, the jumping phenomenon was observed for droplets with initial radius of up to 500 μm. Lastly, our study also reveals that a critical contact angle for droplets to jump upon coalescence is θc ∼ 140°.

Item Type: Article
Identification Number: https://doi.org/10.1016/j.applthermaleng.2016.06.128
Date: 21 June 2016
Uncontrolled Keywords: Condensation heat transfer;Super-hydrophobic surface;Jumping droplets velocity;Multi-disciplinary optimisation
Subjects: F900 Others in Physical Sciences
H100 General Engineering
H300 Mechanical Engineering
Divisions: Faculty of Computing, Engineering and the Built Environment
Depositing User: Zinedine Khatir
Date Deposited: 28 May 2020 09:12
Last Modified: 28 May 2020 09:12
URI: http://www.open-access.bcu.ac.uk/id/eprint/9272

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