本文使用Fortran compiler無因次化模擬奈米相變化乳液與Al2O3奈米流體以同方向分別流於外壁等熱通量加熱之水平同心圓管外環與內管層流強制對流熱傳遞效應。從物理面來看，高熱傳導係數的奈米流體和相變化過程中能發揮潛熱效應的奈米乳液則在下述這些參數的變化過程中扮演影響溫度場的重要角色：無因次外管半徑 、外內管平均速度比 、奈米流體體積分率 、奈米相變化乳液之質量分率 、修正的史蒂芬數 與次冷參數 。此外，熱傳遞效益與考慮等效壓降的FOM則被使用來評估各種不同流體組合的雙管速度完全發展共軛流之熱傳遞增益，比較的對象則是內外管都以水為工作流體的雙管或是以水為工作流體的單管。結果顯示，當外管的奈米乳液可以充分在整個加熱段表現出它的潛熱優勢，並且有不錯的對流強度和潛熱量時，最高的熱傳遞效應與FOM可以分別達到10.1和3.71，如此好的熱傳增益已經超過過去使用機能性流體在單管內的相關研究。而結果也近一步發現，內管無論是純水或是奈米流體，對於抑制外管壁溫的上升並沒有太顯著的效果，主要原因來自於內管和外管外壁仍然不是直接的接觸，因此影響的效果相當有限。

In present study, conjugate laminar forced convection heat transfer characteristics of separated nano-PCM suspension in the annulus space and nanofluid in the inner tube by a horizontal concentric double-pipe duct are investigated under the constant heat flux over the external surface of the annular tube through the dimensionless numerical simulation with Fortran compiler. The parameters including dimensionless outer tube radius , the bulk velocity ratio of outer tube over inner tube , volumetric concentration of nanofluid , mass concentration , Stefan number and subcooling factor of nano-PCM suspension are used to explore the temperature profile distribution concerned with the high thermal conductivity of nanofluid complementary with the latent heat mechanism from nano-PCM emulsion during the melting process. Furthermore, the heat transfer effectiveness and FOM, which incorporates the effective pressure drop, are introduced to evaluate the overall heat transfer enhancement of the hydrodynamically fully developed concurrent parallel flows for various fluids combination in the annulus and inner tube compared with the condition of double tube or single tube employing pure water as working fluid. The results show the highest heat transfer effectiveness and FOM at the end of heated section could reach up to 10.1 and 3.71 as the melting nano-PCM emulsion with the great fluid convection and quantity of latent heat covers the whole heated section in the outer tube. Such a great enhancement has exceeded previous single tube study. Moreover, the results also indicate the inner tube flow could not play a crucial role in the outer tube wall suppression due to the non-direct contact of the two tubes whether the fluid is pure water or nanofluid.

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