Journal of ILASS-Korea (한국분무공학회지)

Institute for Liquid Atomization and Spray Systems-Korea (한국분무공학회)
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Effects of Droplet Temperature on Heat Transfer During Collision on a Heated Wall Above the Leidenfrost Temperature

Leidenfrost 온도 이상의 가열 벽면과 충돌 시 열전달에 대한 액적 온도의 영향

  • Received : 2016.03.15
  • Accepted : 2016.05.23
  • Published : 2016.06.30
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Abstract

This study experimentally investigated the effects of droplet temperature on the heat transfer characteristics during collision of a single droplet on a heated wall above the Leidenfrost temperature. Experiments were performed by varying temperature from 40 to $100^{\circ}C$ while the collision velocity and wall temperature were maintained constant at 0.7 m/s at $500^{\circ}C$, respectively. Evolution of temperature distribution at the droplet-wall interface as well as collision dynamics of the droplet were simultaneously recorded using synchronized high-speed video and infrared cameras. The local heat flux distribution at the collision surface was deduced using the measured temperature distribution data. Various physical parameters, including residence time, local heat flux distribution, heat transfer rate, heat transfer effectiveness and vapor film thickness, were measured from the visualization data. The results showed that increase in droplet temperature reduces the residence time and increases the vapor film thickness. This ultimately results in reduction in the total heat transfer by conduction through the vapor film during droplet-wall collision.

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References

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