Boiling Curve and Droplet Evaporation Lifetime on Hot Hemispherical Copper Surface

Abstract

The objective of this paper is to investigate the droplet evaporation lifetime and boiling curve on hot copper surface using ethanol liquid. We focus our study to find the Critical Heat Flux (CHF) and Leidenfrost temperature in the boiling curve. Copper material which has a high thermal conductivity, k was chosen as a test material. The copper material dimension was approximately 28.0 mm in height and 50.0 mm in diameter. The copper surface was modified into hemispherical surface in order to maximize the evaporation lifetime. The hemispherical surface was constructed using Electrical Discharge Machining (EDM). After completing the EDM process, the dimension of the hemispherical surface area was approximately 15.0 mm in depth and 30.0 mm in diameter. Meanwhile, ethanol liquid which has a low boiling point of 78 °C was chosen as a test fluid. The droplet diameter was approximately 3.628 mm. The impact height was set to be around 4.0 mm corresponding to drop impact velocity of 0.886 m/s. As a result, it was found that the critical heat flux (CHF) and Leidenfrost temperature range on hemispherical copper surface was approximately TCHF = 100.4-117.7 °C and TL = 170.0-175.8 °C, respectively.