CHF Simulation using a Non-Heating Experimental Method

In this paper, the authors propose the non-heating experimental methodology in order to simulate CHF situation, which is hard to establish because of its harsh condition through the heat transfer experiment. The authors employed sulfuric solution copper electroplating system, which generates hydrogen vapor at the surface. When potential is applied, the hydrogen ions dissolved in the solution reduce at the cathode surface as current flows. In order to verify our newly introduced methodology, the measured Critical Mass Flux (CMF) and observation results were compared with CHF results of the previous heat transfer studies. CHF phenomena is simulated by hydrogen gas using copper electroplating system. Vapor behavior on present work experiment was visualized using high speed camera, and it was similar to that of on the heat transfer. CMF value was measured by hydrogen gas with high current value. Thus, this measured CMF value was transformed to the CHF value using isovolumetric concept. However, the transformed CHF from this work was 25 times smaller than that of the previous heat transfer results with identical geometry condition. The departure bubble diameters of hydrogen were measured. The average departure hydrogen bubble diameter was 0.124 mm. Meanwhile, previous heat transfer results for water were from 2 mm to 3 mm. The authors insisted that the certain interaction between solid surface-to-hydrogen gas such as electro-chemical reaction may cause this results. The authors also suspect that this result was dependent on small departure bubble diameter of hydrogen. It is concluded that consideration for these discrepancies need additional parametric analysis: two phase and two component system, surface wettability, electro-chemical reaction, etc.