本文採用數值模擬與實驗量測的方式，探討進口溫度對氧化鋁-水奈米流體於一等熱通量加熱圓管內層流強制對流特性與效益之影響。文中所採熱發展對流數學模式，係將管壁熱傳導效應列入考慮。數值模擬所考慮相關參數及其範圍包括：奈米流體之氧化鋁微粒體積分率，np = 2 ~ 10 vol.%；雷諾數，Ref = 55 ~ 1800；無因次進口溫度，in =10.02 ~ 26.75；無因次加熱段長度，lh= 0.1；及無因次管壁厚度，tw = 0.17。數值模擬結果顯示藉提高進口溫度可有效提高奈米流體之對流冷卻性能增益，且降低其對流熵增，致使可用能性能提升。另外，本研究之強制對流熱傳遞實驗係使用圓銅管測試迴路，其內外徑分別為3.4 mm與4 mm，測試參數及其範圍計有：奈米流體之氧化鋁微粒質量分率，np = 2 ~ 10 wt.%；雷諾數，Ref = 168~2031；進口溫度，Tin = 25℃與50℃；加熱段外壁熱通量，qo" = 3979 ~ 7957W/m2。本研究所得對流熱傳遞實驗數據與對應之數值模擬預測結果比較頗為相符; 因此，證實氧化鋁-水奈米流體相較於純水之層流強制對流冷卻效益可藉提高其進口溫度而更為有效提升高達1.11，且能有效降低其流動摩擦因子，致使其冷卻效能指標明顯上升為1.07。

In the study, the cooling effectiveness and exergetic performance of Al2O3-water nanofluid in laminar forced convection flow in an iso-flux heated circular tube are explored by combined numerical and experimental approach, focusing particularly on the effect of inlet temperature. Numerical simulations based on a conjugate heat transfer model have been undertaken for the pertinent parameters in the following ranges: the nanoparticle volume fraction, np = 2 ~ 10 vol.%; the Reynolds number, Ref = 55 ~ 1800; and the dimensionless inlet temperature, in =10.02 ~ 26.75. The numerical results show that increasing inlet temperature further gives rise to significant benefits on the cooling effectiveness of the nanofluid flows and reduces with lower entropy production rate, also increases available exergy. On the other hand, experiments have been performed using a copper tube of inner and outer radii of 3.4 mm and 4 mm for the relevant parameters in the following ranges: the mass fraction of nanoparticles, np = 2 ~ 10 wt.%; the Reynolds number, Ref = 168 ~ 2031; the inlet temperature, Tin = 25℃ and 50℃, and the imposed heat flux, qo" = 3979 ~ 7957W/m2. The experimental results clearly exhibit a good agreement with the corresponding numerical simulations, further confirming that for the parameters ranges considered, the laminar cooling effectiveness of the nanofluid flow can be further enhanced up to 1.11 by increasing the inlet temperature, which meanwhile induces significantly lower pressure drop and thus the friction factor. As a results, the maximum value of up to 1.07 for the figure of merit of using the nanofluid to replace the water as the cooling fluid can be achieved as the inlet temperature is raised to 50 C.

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