사각채널 내 난류촉진체 형상조건에 따른 전열성능 향상에 관한 수치해석 연구

Abstract

The rapid increase in the use of fossil fuels since the industrial revolution has been accompanied by the conventional usse of fossil fuels, as well as the depletion of conventional fossil fuels, as well as environmental problems, mineralization of resources in resource-rich countries, and waste. In order to cope with these resource and environmental problems, the necessity and urgency for the development of alternative energy such as renewable energy will be even greater. The research on solar and photovoltaic systems using dual solar energy has been actively carried out. In the case of photovoltaic modules, the power generation efficiency is decreased due to the temperature rise due to the solar radiation input. In order to solve the problem that occurs lower than the autumn, when the heat transfer to the air channel through which the air flows from the back surface of the solar cell is caused, only a simple air channel is installed, so that both the solar heat air and the air solar / Heat efficiency is shown. Therefore, it is necessary to improve the heat transfer performance from the absorption plate or the solar module into the air channel. One of these methods is to install a turbulence promoter in the air channel to increase the local velocity between the upper heat transfer portion and the flow air and to change the air flow by the turbulence promoter in the air channel that can make heat transfer performance becomes higher. Thus, in this study, numerical analysis for confirming heat transfer and pressure drop according to the shape of turbulent promoter was conducted. The purpose of this study is to find suitable shapes for the system. The turbulence promoter was installed in a heat transfer section in a rectangular channel for triangular, pin type, quadrant and square shapes. Heat flux of 1000W/m2 was applied to the upper side surface as a heat source. Heat transfer performance was evaluated according to the shape of the turbulence promoter. As a result, it was found that heat transfer performance was improved from 1.29 times to 1.45 times when the square shape turbulence promoter was installed than the heat transfer in smooth duct. Also results show that the heat transfer performance increases significantly in the order of triangle, pin type, and quadrant. In case of friction factor representing pressure drop have a large value in the order of pin type, triangle, square, and quadrant. It is also found that the value increases from 5.41 times to 11.4 times. In addition, it was confirmed that the increase of the pressure drop was accompanied by the increase of the heat transfer performance due to the installation of the turbulence promoter in the square channel. Therefore, performance factor considering both the improvement of the heat transfer performance and the increase of the pressure drop was also confirmed and higher value was shown in order of square, triangle, quadrant, and pin type turbulence promoter. Thus, it is considered that the rectangular shaped turbulence promoter is suitable for practical application in the future. However, in case of square shape, the performance varies depending on the installation interval, height and length in the square channel. So, it is need to be carry out an additional examination of heat transfer and pressure drop with change of installation conditions for finding optimal installation conditions of this turbulence promoter.