高溫高壓同心圓熱交換器幾何設計與分析

本研究是以數值方法設計出溫度高達1000℃之高溫高壓同心圓熱交換器，利用ANSYS Workbench結合三維熱流與結構之熱固耦合分析。改變同心圓熱交換器熱流道內鰭片之厚度、角度、間距、長度與流道寬度，進行同心圓熱交換器整體性能分析與內流道熱對流探討。計算流體力學軟體使用ANSYS FLUENT，工作流體熱流為氦氣，冷流為熔融鹽類，冷流和熱流流動方向以逆向流進行熱交換。熱交換器流道內的流體為穩定且不可壓縮之紊流，在幾何參數範圍之選擇鰭片厚度為0.375~1.125mm、鰭片角度2.6~3.4?、鰭片間距1.7~2.1mm、鰭片長度7~11mm以及流道寬度1~8mm，經過田口法與參數分析結果得知最佳的熱傳參數分別為鰭片厚度1.125mm、鰭片角度2.6°、鰭片間距2.1mm、鰭片長度11mm和流道寬度1mm，可以提升同心圓熱交換器約12%的有效度，熱交換器之有效度提升至0.93。藉由本研究可以發現鰭片幾何改變對同心圓熱交換器有效度之影響權重，使得設計出來的熱交換器改變小幅度的幾何結構，能獲得熱交換器整體有效度明顯之提升，且對熱交換器之結構進行熱應力之探討，可使得設計出來的同心圓熱交換器兼具熱傳高和熱應力低，能使得熱交換器使用壽命更長，對於之後探討熱交換器是一大助力。

關鍵字

熱交換器；有效度； CFD ；逆向流；田口法

並列摘要

The computational fluid dynamics (CFD) approach has been used to simulate three-dimensional concentric heat exchanger in this research. In order to reduce the burden of the computational time, the concentric heat exchanger was simplified with a angular sector of 3° to represent the internal shape and geometry. The hot and cold streams working fluids with flow oppositely are helium and molten salt, respectively. This study mainly focuses on the distribution of field for the two layers of concentric heat exchanger. The width, the length, the pitch, the thickness and the fin angle of the flow channel have been parametrically analyzed by using the effectiveness-NTU (ε-NTU) method. The individually parametric studies and the optimal combination results showed that the best combination for fin thickness, angle, space, length, and flow channel for heat transfer are 1.125mm, 2.6°, 2.1mm, 11mm, and 1mm in sequence. The result indicates about 70% of effort in experiments or simulations could be saved. The research has found that appropriate modification in geometry can significantly improve the performance in both heat transfer and thermal stress.

並列關鍵字

Heat exchanger ； CFD ； counter flow ； ε-NTU ； Taguchi method

參考文獻

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國際替代計量

高溫高壓同心圓熱交換器幾何設計與分析

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