絕熱與臨界熱傳問題之研究和共軛梯度逆向分析法在管流與衝擊流熱傳問題的應用

The study of heat transfer problems related to insulation, critical phenomena and applications of conjugate inverse method on pipe and impinging jet

李昂

指導教授 ： 黃景良

共同指導教授 ： 陳文立

崑山科技大學/工程學院/機械與能源工程研究所/博士(2010年)

https://doi.org/10.6828/KSU.2010.00074

摘要

本論文將共軛梯度逆向運算法應用在兩個重要的熱傳問題：(1)用管壁溫度估算圓管管壁積垢層的厚度，(2)估算衝擊流冷卻問題中噴流出口的溫度。在第一個問題中，經由直接問題計算所獲得的溫度被當做實驗量測溫度(又稱模擬溫度)代入逆向運算中；而結果顯示本論文對二維與三維的圓管均可準確地估算出其管壁積垢層的厚度分佈。在第二個問題中，只要給定平板上需要冷卻的範圍與此範圍內可容許的最高溫度，逆向運算法即可計算出達成這兩項要求的噴流出口溫度。將此方法用在兩個衝擊流冷卻問題中，以逆向運算法計算的噴流出口溫度代入直接問題中所得的平板上最高溫度與給定的最高溫度相差不到1%。本論文所發展的方法可做為在超音波積垢層測量法之外的另一選擇，它可簡單且準確地估計出積垢層厚度以做為排定管路維護計畫時的重要參考數據。另外，當它應用在衝擊流冷卻問題時所穫得的資訊可做為設計冷卻系統時的依據。在工業上這兩者均有極高的應用價值。

關鍵字

絕熱 ； 臨界熱傳 ； 逆向運算法 ； 積垢層 ； 圓管管路 ； 共軛梯度 ； 衝擊流 ； 噴流出口溫度

並列摘要

In this study, a conjugate gradient method based inverse algorithm is applied to estimate the unknown three-dimensional fouling-layer profiles on the inner wall of a piping system using simulated temperature measurements taken on the pipe wall and the inlet jet temperature in an impinging jet cooling problem. For the piping system the temperature data obtained from the direct problem are used to simulate the exact temperature measurements. Results show that an excellent estimation on the fouling-layer profiles can be obtained for the cases investigated in this study. In the impinging jet cooling problem, given the maximum allowable plate temperature and the extent of the area on plate where temperature needs to be controlled, the jet temperature required to meet the two demands can be determined. The tests in two scenarios show that very accurate inlet jet temperatures were returned, resulting in a maximum temperature less than 1% difference with the specified temperature within the specified area. For the pipe fouling problem, the techniques presented here can be used as an alternative to ultrasonic waves fouling detection techniques to provide crucial information for the optimization of cleaning schedule for piping systems; and for the impinging jet problem, the method can be a great assist to engineers to design adequate thermal management systems for devices or processes requiring jet impingement cooling.

並列關鍵字

Insulation ； critical heat transfer ； inverse problem ； fouling layer ； pipe system ； conjugate gradient method ； impinging jet cooling ； inlet jet temperature

參考文獻

[2]. M. Markowski and K. Urbaniec, Optimal Cleaning Schedule for Heat Exchangers in a Heat Exchanger Network, Appl. Thermal Eng., vol. 25, pp. 1019-1032, 2005.

[3]. S. Sanaye and B. Niroomand, Simulation of Heat Exchanger Network (HEN) and Planning the Optimum Cleaning Schedule, Energy Conv. Manag., vol. 48, pp. 1450-1461, 2007.

[4]. B. Bansal, H. Muller-Steinhagen, and X. D. Chen, Comparison of Crystallization Fouling in Plate and Double-pipe Heat Exchanger, Heat Transfer Eng., vol. 22, pp. 13-25, 2001.

[5]. K. R. Lohr and J. L. Rose, Ultrasonic Guided Wave and Acoustic Impact Methods for Pipe Fouling Detection, J. Food Eng., vol. 56, pp. 315-324, 2003.

[6]. T. R. Hay and J. L. Rose, Fouling Detection in Food Industry Using Ultrasonic Guided Waves, Food Control, vol. 14, pp. 481-488, 2003.