Abstract
In this study, an experiment on the evaporation of nanofluid sessile droplet on a heated surface was conducted. A nanofluid of 0.5% volumetric concentration mixed with 80-nm-sized CuO powder and pure water were used for experiment. Droplet was applied to the heated surface, and images of the evaporation process were obtained. The recorded images were analyzed to find the volume, diameter, and contact angle of the droplet. In addition, the evaporative heat transfer coefficient was calculated from experimental result. The results of this study are summarized as follows: the base diameter of the droplet was maintained stably during the evaporation. The measured temperature of the droplet was increased rapidly for a very short time, then maintained constantly. The nanofluid droplet was evaporated faster than the pure water droplet under the experimental conditions of the same initial volume and temperature, and the average evaporative heat transfer coefficient of the nanofluid droplet was higher than that of pure water. We can consider the effects of the initial contact angle and thermal conductivity of nanofluid as the reason for this experimental result. However, the effect of surface roughness on the evaporative heat transfer of nanofluid droplet appeared unclear.
Highlights
The boiling and evaporation of droplet are very important phenomena for industrial applications using atomized liquids such as fuel spray, spray cooling, and spray painting.[1,2,3] Baumeister and Simon[4] studied the evaporation of droplets on a hot surface and reported a prediction technique for the Leidenfrost temperature
In prior studies by the author, the contact angle of nanofluid droplet was experimentally researched as a basic approach to the phase change heat transfer of nanofluid.[16]
The result of this study showed that the initial contact angle of the droplet increased with the surface roughness and that the Department of Mechanical & Automotive Engineering, Andong National University, Andong, South Korea
Summary
The boiling and evaporation of droplet are very important phenomena for industrial applications using atomized liquids such as fuel spray, spray cooling, and spray painting.[1,2,3] Baumeister and Simon[4] studied the evaporation of droplets on a hot surface and reported a prediction technique for the Leidenfrost temperature. Choi and colleagues[11,12] reported that the thermal conductivity of nanofluid could be enhanced compared to pure liquid, and studies on the application of nanofluid in phase change heat transfer (boiling, evaporation, etc.) have been conducted.[13,14,15] In prior studies by the author, the contact angle of nanofluid droplet was experimentally researched as a basic approach to the phase change heat transfer of nanofluid.[16] The result of this study showed that the initial contact angle of the droplet increased with the surface roughness and that the Department of Mechanical & Automotive Engineering, Andong National University, Andong, South Korea
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