Effect of temperature difference on condensation heat transfer and droplet distribution on hydrophilic and hydrophobic surfaces

Document Type : Research Article

Authors

School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran

Abstract

The research examined the influence of temperature difference between surfaces and humid air on heat transfer and droplet distribution. A testing apparatus controlled environmental conditions and facilitated condensation on hydrophilic and hydrophobic surfaces. The relative humidity and speed of humid airflow were kept constant at 88% and 5 m/s, respectively, and the temperature difference considered was 4, 7, and 10 degrees Celsius. The varying heat transfer overtime during the 60 minutes has shown that it takes time to start the condensation process; the more the temperature difference and the amount of surface energy, the shorter this time is and the higher the average heat transfer is. The photography of the experiments has also shown that with the increase in temperature difference and surface energy, the time required for the first drop to fall is shorter, and the hydraulic diameter of the dropped drop is bigger. The distribution of the droplets in the 20th minute after the start of each experiment, in which no droplets have left the test surfaces yet, shows that with the increase in the temperature difference, the number of larger droplets is more due to the increase in the condensation rate. The number of the smallest droplets is higher on hydrophobic surfaces than on hydrophilic ones.

Keywords

References

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Amirkabir Journal of Mechanical Engineering
Volume 56, Issue 6
September 2024
Pages 811-832

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