雙螺旋殼圈式熱交換器之性能模擬分析

Simulation of Shell and Double Helical Coiled Heat Exchanger

張桓銘(Huan-Ming Chang)

指導教授 ： 簡良翰

國立臺北科技大學/機電學院/能源與冷凍空調工程系碩士班/碩士(2012年)

https://doi.org/10.6841/NTUT.2012.00539

摘要

本研究分析雙螺旋殼圈式水對水熱交換器之熱傳現象，並利用水為工作流體，固定入口溫度，再經由改變壁面溫度(296~321K)、入口流速(0.5~5 m/s)、曲率直徑(96mm、142mm)和間距(21、31.08mm)，以計算殼圈式熱交換器之螺旋管管內熱傳與壓損。利用固定管側溫度與入口流量，改變殼側入口溫度(323~333 K)與流速(2~4 m/s)，探討殼側熱傳性能。並參考文獻中各種參數範圍之壓損與熱傳經驗公式，而求得本研究之壓損與熱傳經驗公式。結果指出在有限的體積下，殼側與管側流量分別為1.18、0.95 kg/s與入口溫度分別為288、333 K的條件下，比較單、雙螺旋管之差異，雙螺旋管雖然在增加其熱交換面積的同時會造成熱傳係數的下降，但是卻能有效提升整體熱交換率，而且並不會造成殼側壓損的增加，且螺旋管內壓損會因為兩根螺旋管而平均分配，可使殼圈式熱交換器壽命延長，並減少維修費用。螺旋管管內壓損會因為曲率直徑的大小而變，當曲率直徑越小時，螺旋管內壓損會越大；流速越大時，壓損也會越大。本研究並分別提出螺旋管內摩擦係數經驗公式，及管內與殼側熱傳經驗公式。

關鍵字

計算流體力學 ； 螺旋管 ； 殼圈式熱交換器

並列摘要

In the present study, numerical investigation of mixed convection and pressure drop in a shell and double helical coiled heat exchanger is reported. Water is the working fluid and inlet temperature is fixed at 288K. Changing wall temperature (296~321K), inlet velocity (0.5~5 m/s), coil diameter (96mm, 142mm), and coil pitch (21, 31.08mm) to determined heat transfer and pressure drop inside helical tubes. In addition, shell side heat transfer and overall heat transfer coefficient are investigated with various shell side inlet temperature and velocity and fixed tube side inlet temperature and flow rate. For fixed shell side and tube side mass flow rate of 1.18, 0.95, respectively, fixed inlet temperature at 288, 333 K, respectively. Single and double helical tubes are compared. The results of the present numerical study indicate that double helical tubes yields lager greater heat exchange rate as a result of larger heat transfer surface area, although it also results in a smaller heat transfer coefficient. The tube side pressure drop is significantly decreased as a result of the split of liquid flow, while only minor influence of shell side pressure drop is found. The helical tube pressure drop increases with decreasing curvature radius, and increasing fluid velocity. This study was asked the empirical formula of the coefficient of friction within the coil, and the tube and shell side heat transfer empirical formula. Based on the results of numerical simulation for various parameters, empirical correlations of pressure drop and heat transfer of both tube side and shell side of a shell and double coil heat exchanger are proposed.

並列關鍵字

Computational Fluid Dynamics ； Helical tubes ； Shell and Coil Heat Exchanger

參考文獻

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