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International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

CHARACTERIZATION OF SURFACE TEMPERATURE OF EVAPORATING SESSILE WATER DROPLETS

Dinghua Hu
MIIT Key Laboratory of Thermal Control of Electronic Equipment, Nanjing University of Science and Technology, Nanjing, 210094, China

Xuemei Chen
MIIT Key Laboratory of Thermal Control of Electronic Equipment, School of Energy and Power Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China; Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong 999077, China

Qiang Li
MIIT Key Laboratory of Thermal Control of Electronic Equipment, School of Energy and Power Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China

DOI: 10.1615/IHTC16.bae.024122
pages 1007-1015


KEY WORDS: Boiling and evaporation, Thermal management, surface temperature, evaporating sessile droplet

Abstract

The surface temperature of sessile droplets can significantly affect its evaporation rate and inside flow field. Empirical expression for the surface temperature in the literature usually was derived from the one-sided model, which neglect the effect of temperature drop of droplet surface on evaporation rate. Numerical simulation and infrared experiment are carried out to investigate the characteristic of surface temperature of evaporating sessile water droplets in this study. The two-sided model coupled with the interaction between mass evaporation and heat transfer at liquid-gas interface is numerically solved by finite element method. An infrared thermography combined with a CCD camera is used to capture the surface temperature distributions of droplets under different contact angles. The results show that the one-sided model is not applicable for predicting the surface temperature of droplet with large contact angle due to the overestimated evaporation rate. Compared to the experimental result, the previous empirical expression can overestimate the maximum temperature drop of droplet surface by 45%, while the predicted deviation of present model is 9.1%. The numerical and experimental results also show that the surface temperature drop of droplet is dominated by the contact angle rather than the contact radius, which is validated by the experimental results.

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