螺紋殼多管式熱交換器之熱傳增益

Heat transfer enhancement in a multi-tube heat exchanger with threaded shell

唐匯驊(HUI-HUA TONG)

指導教授 ： 翁輝竹

中原大學/工學院/機械工程學系/碩士(2022年)

https://doi.org/10.6840/cycu202201364

摘要

本論文完成螺紋殼多管式熱交換器在不同的螺紋高度跟形狀及螺紋的相對位置來進行研究，考量參數為無因次殼管螺紋高低跟無因次螺距(管件螺紋與殼管螺紋相對位置)，並且對螺紋殼多管式熱交換器進行模擬分析。使用ANSYS Fluent並採用k-epsilon standard標準模型模擬分析，在不同的雷諾數下(8800、10900、16600、27500、55300及82900)，進而探討努賽爾數、摩擦係數及PEC值(性能增強係數)。在第一階段進行不同的螺紋形狀，於無因次殼管螺紋高低之所探討結果中選出最佳努賽爾數之螺紋形狀及高度，在選出適當的高度之後，進行第二階段的無因次螺距之探討，並找出具最佳努賽爾數之螺距模擬之結果。
本研究結果發現，在所探討之參數範圍內，在第一階段的模擬結果奴賽爾數會隨著雷諾數增加，所探討的圓弧形、長方形、三角形中，最為理想的形狀為圓弧形，圓弧形努賽爾數為最高，PEC值也都大於1，長方形及三角形無因次化螺紋的性能皆不如圓弧形，第二階段模擬是在模擬無因次螺距(管件螺紋至殼管螺紋相對位置) ，在這階段的模擬，努賽爾數最好的位置卻不是中間的位置，中間偏前面一點的位置才是最好的，其他位置效果都不如預期的好。

關鍵字：多管式熱交換器、螺紋殼、性能增強係數、摩擦係數

關鍵字

多管式熱交換器 ； 螺紋殼 ； 性能增強係數 ； 摩擦係數

並列摘要

In this paper, the threaded shell multi-tube heat exchanger has been studied at different thread heights, shapes, and relative positions. The parameters of discussion are the dimensionless shell height and dimensionless thread pitch (the relative position between tubular threads and shell threads). Simulation analysis of this study was performed using ANSYS Fluent with the k-epsilon standard model to simulate and analyze under different Reynolds numbers (8800, 10900, 16600, 27500, 55300, and 82900). The resulting Nusselt number, friction coefficient, and PEC value (performance enhancement coefficient) are then discussed.
During the first stage of the simulation, different thread shapes and dimensionless thread heights were compared respectively. After the thread shapes and the thread heights with the best Nusselt number were chosen, the second stage of the simulation was then conducted. This stage focuses on finding the dimensionless thread pitch with the best Nusselt number.
It was concluded that within the range of parameters discussed, the Nusselt number discussed in the first stage of the simulation increased with the Reynolds number. Among the arc, rectangle, and triangle shapes discussed, the most ideal shape was the arc. The Nusselt number of the arc-shaped tube is the highest, and the PEC value is also greater than 1. The rectangular and triangular dimensionless shell and tube threads did not perform as well as the arc shape. According to the results from the second stage of the simulation, the position of the thread pitch with the best performing Nusselt number is not the middle position; rather, the position that is closer to the front yields a better result. The results of all the other positions did not perform as well as expected.

Keywords: Multi-tube heat exchanger; Threaded shell; Performance enhancement factor; Coefficient of friction

並列關鍵字

Multi-tube heat exchanger ； Threaded shell ； Performance enhancement factor ； Coefficient of friction

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