4349 水平平滑管内CO_2蒸発熱伝達率への質量速度と熱流束の影響に関する実験的研究(S58 高効率ヒートポンプの要素技術とその応用,S58 高効率ヒートポンプの要素技術とその応用)

概要

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The CO_2 heat pump water heater has a high potential for energy conservation and greenhouse abatement. To encourage the broader use of the heat pump water heater, it is necessary to develop space saving and high efficient equipment. The most important element is always the evaporator. Experimental studies have been conducted to measure the pure CO_2 (99.999% purity, without oil) flow boiling heat transfer coefficient in a horizontal smooth tube (outer diameter 6mm, thickness 0.4mm). In our previous report, the mean heat transfer coefficient had a peak value at a certain mass velocity or a heat flux, but which influence strongly affected the result was not understood. In this report, to distinguish the influence of mass velocity and that of heat flux to the heat transfer coefficient, the tube length is varied to 3.0m, 4.0m and 5.0m. The test conditions were: CO_2 mass velocity from about 150 to about 700kg/(m^2s), saturation temperature of CO_2 are about 0, 5 and 10℃, quality at inlet of test section is fixed to be 0.17 and CO_2 super heat at outlet of test section is fixed to be 5K. As a result, it has been understood that heat flux has a greater influence on the heat transfer coefficient.
一般社団法人日本機械学会の論文
2006-09-15