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Title: 鰭管式空氣加熱器之熱特性分析
Heat Transfer Characteristics On Fin-Tube Air Heaters
Authors: Sheng-Yao Ke
Contributors: NTOU:Department of Mechanical and Mechatronic Engineering
Keywords: 鰭管式熱交換器;鰭片;對數平均溫差法
Fin-tube heat exchanger;fin;LMTD method
Date: 2010
Issue Date: 2011-06-30T07:29:34Z
Abstract: 本研究主要係探討管側內部工作流體為熱煤油、水、水蒸氣或空氣之鰭管式空氣加熱器之熱傳特性。分別計算其雷諾數及熱對流係數,運用對數平均溫差法計算熱傳面積,以及需要的管數及壓降。 計算程式使用Microsoft Excel撰寫,程式內含相關物理性質並具查詢功能,程式在給定條件下,首先驗證能量平衡,次由使用者輸入設計參數,以進行評估或設計的工作,藉由電腦作業方式,快速準確的運算,以提升複雜、冗長的計算效率,並達減少錯誤之目的。如此ㄧ來可降低實驗作業成本,亦可節約運算過程時間,同時讓使用者簡便的在最短時間內,達到設計最佳化及最有效率的結果。 本研究所撰寫程式,可依傳熱管的尺寸及操作溫度調整傳熱管之長度、排列方式、外徑、厚度、間距、垂直管數、水平列數以及迴流數等不同條件下進行,針對鰭片之厚度、高度及鰭片排列密度,進行性能的評估,進而提供使用者所需運用參數。 關鍵字:鰭管式熱交換器、鰭片、對數平均溫差法。
The objective of this study is to investigate the thermal characteristics of fin-tube air heaters by runing Dowtherm oil, water, steam and dry air respectively inside the tube. The Reynolds number, heat transfer convection coefficients inside and outside the tube are calculated, therefore the heat transfer area and the number of tubes are obtained by LMTD method. In addition, the layout of the tubes are studied accompanied withe the pressure drop required. The computer program “Excel” developed by Microsoft was used to handle this problem. The temperature dependent physical properties are inquired from the date base sheets. First of all, the energy balance was made according to the inlet/outlet temperature and mass flow rate of the fluids. The energy transfer between the hot and cold fluid must be met each other before the execution of the program. Through the variation in the input parameters the optimization work based on the minimum heat transfer area and acceptable head loss can be accessed. Different cases with the change in diameter, length, layout, and spacing of tubes are studied. Finally, the effect of variation on thickness, height and pitch of fins are also presented. Keywords : Fin-tube heat exchanger、fin、LMTDmethod.
Appears in Collections:[Department of Mechanical and Mechatronic Engineering] Dissertations and Theses

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