진동형 히트파이프의 증발관 형상에 따른 이중 진공관 태양열 집열기의 성능 특성에 대한 연구

Abstract

Solar heat energy, one of the typical renewable energy absorbs radiation energy from the sun and converts it into heat energy. Since it is sustainable and eco-friendly, it can be a good alternative to solve the problem of the depletion of fossil fuels. But it has low density. So, solar collector is very important to use more efficiently. From the viewpoint of low cost as well as short construction schedule for the manufacturing of heat exchanger, flexibility, and high performance, Pulsating Heat Pipe (PHP) draws special attention. Therefore, we use PHP for increasing efficiency of solar collector. We made evaporating section of PHP by using a ‘U’ shape to prevent flooding which is the problem of conventional ‘I’ type heat pipe of solar collector. Condensing section of PHP was double tube which has the circular finned water tube inside for increasing heat transfer area. In this study, we applied three type PHPs to solar collectors. All PHPs have same condensing section shape, but evaporating section is different. Collector Ⅰ has Double U type which installed two 'U' tube in the evaporating section for increase heat transfer area. Collector Ⅱ, Ⅲ have U type PHP which installed one 'U' tube of different diameters and has more simple shape than Collector Ⅰ. All PHPs were charged R-141b about 100% of evaporating section volume. We compare the solar collector efficiency according to the evaporating section shape of the PHP on standard water flow rate. Also, we calculate flooding limit of PHP for theoretical verification of experimental results. Consequently, theoretical results and experimental results had shown identical trend. Collector Ⅲ has the best performance and it works reliably on the standard water flow rate.