| Summary: | 碩士 === 國立臺南大學 === 機電系統工程研究所 === 102 === This thesis experimental carbon dioxide for heat transfer performance at supercritical in vertical stainless steel circle tube with outside diameter 12.7 mm and inside diameter 10.0 mm and length 1.8 m, in order to simulation supercritical carbon dioxide flow into reservoir, the silica-based porous media is added and to analysis effect of different particle diameter.
The system pressure was set at 7.5, 10, or 14 MPa; the flow rate was set at 10, 30, 40, or 50 mL/min; and the initial wall temperature was set at 150 or 200 ºC to determine the behavior of supercritical carbon dioxide and compare with/without porous media. The results showed that carbon dioxide property changes very dramatically at pseudo-critical point, heat transfer of supercritical carbon dioxide depend on temperature affect, after far from pseudo-critical point the heat transfer coefficient was changes very smooth, and then can found pressure insignificantly affected; 10.3 MPa is optimal operating pressure, because of thermal equilibrium temperature is close to 46.85 ºC at 10 MPa. The results showed that, compare with/without porous media, that effect of heat transfer is enhanced when porous media is added, the reason is the contact area increases between the working fluid and porous media, moreover, heat transfer increased with particle diameter decrease result from the flow velocity increased can carry more heat when supercritical carbon dioxide flow through porous media. This study will provide the effective data for regarding the operating conditions of the enhanced geothermal system.
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