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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/13882

Title: 超臨界水之熱交換器系統設計
Heat Exchangers System Design Powered by Supercritical H2O
Authors: Sin-Wei Kao
Contributors: NTOU:Department of Mechanical and Mechatronic Engineering
Keywords: 套管式熱交換器;壓力容器;超臨界水
double pipe;pressure vessel;supercritical
Date: 2010
Issue Date: 2011-06-30T07:29:32Z
Abstract: 中文摘要 本文中透過溫度與壓力區分超臨界及亞臨界水,以臨界點374℃壓力22MPa為界線。由於達超臨界狀態時,能有效提升負載率,但缺點即是材料承受高溫高壓及沖蝕現象。因此,必須首先對熱交換器胴體做安全性計算,而在本文中,強度與熱傳的取捨下,必需視強度為優先。 於安全性計算方面,必須符合國家標準規範(CNS),依照規範要求,在本熱交換器系統中,使用的SUS316L與Inconel-718兩種材料的材料容許拉應力,計算出胴體所需要的最小厚度。接著熱傳方面,採用LMTD方法來計算,並且分段求得總括熱傳係數與總熱傳面積,以估算熱交換器熱管之總長度。 在設計過程中,為方便計算,建立了一套Excel計算書,並且藉由不斷調整參數數值,以求得最佳化設計。總括熱傳係數中,由於內外管皆為純水,因此省略掉污垢係數後可分為三項熱阻力,分別為Ri、Rwall以及Ro,本文針對這三項阻力,利用調整鰭片長度、寬度與熱管厚薄度,以促使阻力趨向最小達到最大熱傳的目標。 關鍵字:套管式熱交換器,超臨界水,壓力容器,鰭片
Abstract The purpose of this thesis is the demarcation between supercritical and subcritical water is based on the critical point of water at 374℃ and 22MPa. While the critical point is accessed, the coexistence of liquid and vapor phases accompanied with high pressure and temperature which results in a higher thermal efficiency state. However, the strength of the structural material should be addressed. As to the strength calculation, the CNS standard was followed. The allowable stresses of SUS316L and Inconel-718 used in the heat exchangers design are found and thus the minimum thickness of pipe can be obtained. LMTD method is used to analyze the required heat transfer area, and the overall length of the heat exchanger is estimated. A computer code written in Excel is developed to handle this problem. By varying the input parameters, an optimal design is recommended. In the thermal analysis, the fouling factors have been ignored due to the usage of distilled water. The summation of the remaining three-term resistance Ri, Rwall and Ro is to be minimized and a higher heat transfer rate is achieved. Key word: Double pipe, supercritical, pressure vessel, fin
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M97720036
Appears in Collections:[機械與機電工程學系] 博碩士論文

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