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The purpose of this research is to study and investigate the evaporation lifetime and boiling curve on hemispherical heated surface. The selected material was stainless steel (304). A nearly perfect and smooth hemispherical surface was developed by using EDM die sinker. For the test liquid, distilled water was used during the experimental work. The average droplet temperature was 31.36 °C corresponding to liquid subcooling ΔT sub = 68.64K. Based on the theoretical calculation, the diameter of the water droplet was approximately 5.00 mm. Meanwhile, the impact height was approximately 65.0 mm corresponding to the theoretical impact velocity of 1.129 m/s. The material was heated using a digital hot plate which was able to give an accurate reading and stable temperature fluctuation during the heating process. The temperature ranged from a low temperature of T w = 100 °C to a high temperature of T w = 300 °C. As a result, the boiling curve showed a similar pattern of other experimental work that consists of two (2) important points which are Critical Heat Flux(CHF) and Leidenfrost temperature.

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The objective of this study is to clarify physical mechanisms involved in the evaporation of small (a few microliters) sessile drops. We aim to understand the relation between local thermal information at the solid-liquid interface and overall evaporation. An infrared (IR) camera and a CCD camera were used to determine the temperature and heat flux distribution at the solid-liquid interface and the profile of the evaporating drop, respectively. The temperature distribution at the solid-liquid interface was determined using a multilayer substrate consisting of a silicon wafer coated with a thin thermal insulator that is partially transparent to IR. The liquids used were water and FC-72. The evaporation rate of water drops was found to occur mostly at the contact line. However, the heat transfer distribution at the liquid-solid interface was relatively uniform, indicating the heat transferred from the wall must be transported within the drop to the contact line. The mechanisms by which this occurs have yet to be determined. In contrast, the evaporation rate of FC-72 drops where hydrothermal waves were present were found to be proportional to the liquid-vapor interface area rather than the circumference of the drop, indicating a more uniform distribution of evaporation.