전기도금계를 활용한 Enclosure내 자연대류 열전달에 관한 연구

Abstract

As a promising future energy source, the concern of hydrogen is increased due to the rising oil prices and environmental pollution. Hydrogen is a non-petroleum-based, non-toxic, renewable and clean burning energy source. One of the promising production methods of hydrogen is to use the heat from an HTGR(High Temperature Gas-cooled Reactor), a next generation nuclear reactor for a safe and reliable operation as well as for efficient and economic generation of energy. The knowledge of detailed heat transfer phenomena in gaseous phase emerges as an important factor for HTGR, where buoyancy effect plays a significant role. Large and expensive test facilities are to be constructed to assess the detailed mixed convection phenomena. However, using analogy concept, heat transfer system can be transformed to mass transfer system and vice versa. If a simple mass transfer system could be devised, and the experimental solution from that system could be obtained, then this could theoretically lead to a solution for a similar heat transfer system. In this study, a copper electroplating system was selected as the mass transfer system. A copper electroplating system with limiting current technique has a good advantage to simulate heat transfer system as mass transfer coefficient, analogous with heat transfer coefficient, can be directly obtained from the information of the bulk concentration and electric current between electrodes. This study simulated the natural convective heat transfer phenomena in enclosure using copper electroplating system. According to the various change in Rayleigh number and aspect ratio, mass transfer experiments were conducted by limiting current technique. In the result of tests, the length between electrodes has no effect on the mass transfer rate in boundary layer regime. However, the mass transfer rate was affected by the height of electrodes and Rayleigh number. In addition to, these results were in good agreement with the well-known heat transfer empirical correlations. This means that the analogy experimental methodology introduced in this study is very valid and encouraged. Consequently, analogy experimental methodology is expected to be a useful tool for heat transfer studies for HTGR as well as the systems with high buoyancy condition, as the electroplating method not only provides useful information regarding heat transfer but also has a cost-effective advantage over any other comparable experimental method.