Numerical investigation on the evaporation of droplets depositing on heated surfaces at low Weber numbers |
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| Authors: | George Strotos Manolis Gavaises Andreas Theodorakakos George Bergeles |
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| Affiliation: | 1. Department of Mechanical Engineering, National Technical University of Athens, 5 Heroon Polytechniou, Zografos, 15710 Athens, Greece;2. School of Engineering and Mathematical Sciences, The City University, Northampton Square, EC1V 0HB London, UK;3. Fluid Research Company, Laskareos 49, 11472 Athens, Greece;1. Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China;2. School of Civil Engineering, Dalian University of Technology, Dalian 116024, China;1. University of Toulouse, The Institute of Fluid Mechanics (IMFT), Toulouse, 2, allée du professeur Camille Soula, 31400 Toulouse, France;2. University of Toulouse, France;3. LEMTA, UMR 7563, Université de Lorraine, France;4. LEMTA, UMR 7563, CNRS, France;1. Institute of Thermophysics Siberian Branch, Russian Academy of Sciences, Lavrentiev Ave. 1, Novosibirsk 630090, Russia;2. National Research Tomsk Polytechnic University, pr. Lenina 30, Tomsk 634050, Russia;1. Institute of Technical Thermodynamics, Technische Universität Darmstadt, Petersenstr. 17, 64287 Darmstadt, Germany;2. Center of Smart Interfaces, Technische Universität Darmstadt, Petersenstr. 17, 64287 Darmstadt, Germany |
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| Abstract: | The evaporation of water droplets, impinging with low Weber number and gently depositing on heated surfaces of stainless steel is studied numerically using a combination of fluid flow and heat transfer models. The coupled problem of heat transfer between the surrounding air, the droplet and the wall together with the liquid vaporisation from the droplet’s free surface is predicted using a modified VOF methodology accounting for phase-change and variable liquid properties. The surface cooling during droplet’s evaporation is predicted by solving simultaneously with the fluid flow and heat transfer equations, the heat conduction equation within the solid wall. The droplet’s evaporation rate is predicted using a model from the kinetic theory of gases coupled with the Spalding mass transfer model, for different initial contact angles and substrate’s temperatures, which have been varied between 20–90° and 60–100 °C, respectively. Additionally, results from a simplified and computationally less demanding simulation methodology, accounting only for the heat transfer and vaporisation processes using a time-dependent but pre-described droplet shape while neglecting fluid flow are compared with those from the full solution. The numerical results are compared against experiments for the droplet volume regression, life time and droplet shape change, showing a good agreement. |
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