迴流效應於管壁正弦熱通量之逆流型套管熱交換器的研究

機構典藏 > College of Engineering > Graduate Institute & Department of Chemical and Materials Engineering > Thesis > Item 987654321/34834

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Title:	迴流效應於管壁正弦熱通量之逆流型套管熱交換器的研究
Other Titles:	The recycle effects on heat transfer in laminar counterflow concentric-tube heat exchangers with sinusoidal wall fluxes
Authors:	楊贄銘;Yang, Chih-ming
Contributors:	淡江大學化學工程與材料工程學系碩士班何啟東;Ho, Chii-dong
Keywords:	共軛格拉茲問題;迴流;圓管型;正弦熱通量;Conjugated Graetz problem;External recycle;Concentric tube;Sinusoidal wall fluxes;Frobenius method
Date:	2006
Issue Date:	2010-01-11 05:40:13 (UTC+8)
Abstract:	本研究是設計圓形管加裝一可忽略熱阻之隔板，使之成為一組外管壁熱通量為正弦函數且具有迴流裝置之逆流型套管熱交換器，此系統所推導出的數學模型將產生一組共軛偏微分方程式，是屬於共軛格拉茲問題(conjugated Graetz problem)，本研究以近似解(approximation method)並利用弗賓納斯法(Frobenius method)來求解，可獲得其管內溫度分佈及納塞數(Nusselt number)，並探討迴流效應對雙套管間的熱傳效率之影響，再將其結果與單行程無隔板系統其熱量傳送作比較，以驗証二行程系統的熱傳效率提升。預混效應及流體流速是影響二行程熱傳效率的兩個因素，本研究討論兩者對系統的影響。結果顯示，本系統在格拉茲數大時，其效率提昇率有明顯改善，而不同的隔板位置對系統之間的效率亦有顯著影響。同時在本文中，迴流系統因隔板裝置及不同的迴流比值而增加的能源消耗率也將與單行程系統作比較，以探討雙套管之加熱系統在低能源消耗率時，熱傳效率改善之最佳操作設計。 Abstract : The new device of double-pass concentric-tube heat exchangers with sinusoidal wall fluxes and external recycle has been developed theoretically in the present study. The approximation solutions to the resultant mathematical formulations for such conjugated Graetz problems were achieved by using the orthogonal principle and Frobenius method. The theoretical results of the temperature distribution and heat transfer efficiency are represented graphically and compared with those in single-pass devices (without an inner tube inserted) of the same working dimensions. The results show that introducing recycle operation can enhance the heat-transfer efficiency in designing double-pass concentric-tube heat exchangers with sinusoidal wall heat fluxes. The influences of the inner tube location and Graetz number on the heat-transfer enhancement and power consumption increment have also been discussed.
Appears in Collections:	[Graduate Institute & Department of Chemical and Materials Engineering] Thesis

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