<紀要論文>
内面螺旋溝付管内単相流の熱伝達および圧力損失

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概要 Experiments on single phase heat transfer and pressure drop inside three kinds of internally grooved tubes and a smooth tube were carried out using water and HCFC22 vapor as test fluids. For the case ...of water, the average heat transfer coefficient over the 1000mm long test section heated electrically and the static pressure drop through the 1400mm long test section were measured in the range of mass velocities of 230 to 1420kg/(m^2s), Reynolds numbers of 8×10^2 to 1.6×10^4 and heat flux of 10 to 47kW/m^2. For the case of HCFC22 vapor, the average heat transfer coefficient over the 800mm long test section, which was heated by water flowing in a surrounding annulus, was measured in the range of mass velocities of 110 to 220kg/(m^2s), Reynolds numbers of 7×10^4 to 2×10^5, vapor pressures of 0.4 to 0.65MPa and heat flux of 5 to 35kW/m^2. For the smooth tube, the measured friction factors agree well with a theoretical equation for fully developed laminar flow inside a smooth tube in the range Re ≲ 2×10^3 and the Colburn equation in the range Re ≳ 3×10^3. The measured heat transfer coefficients in the range 3×10^3 ≲ Re ≲ 7×10^3 are in better agreement with the values predicted by the Gnielinski equation using the Blasius equation than those using the Colburn equation. For the internally grooved tubes, the measured friction factors are about 20% higher than the theoretical equation for a smooth tube in the range Re ≲ 2×10^3 and about 5 to 9% higher than the Blasius equation in the range 3×10^3 ≲ Re ≲ 7×10^3. In the range Re ≳ 7×10^3, the measured values increase with the increase of Reynolds number, having a different tendency from empirical equations for a smooth tube. The measured heat transfer coefficients for the grooved tubes agree well with those for the smooth tube in the range 3×10^3 ≲ Re ≲ 7×10^3, while the former values are higher than the latter ones in the range Re ≳ 7×10^3. An empirical equation for heat transfer coefficients of the grooved tubes is also obtained in the range 10^4 ≲ Re ≲ 2×10^5.続きを見る

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登録日 2009.04.22
更新日 2017.03.28