臺灣博碩士論文加值系統

摘要

本研究旨在探討熱交換器之熱傳特性，實驗上建立了一套量測系統，具有冷、熱□溫槽，可經由循環泵引流經過板式或殼管式熱交換器，藉由量測溫度來計算出總括熱傳係數，U值。
根據實驗中的觀察，在實驗過程中，可以得知板式熱交換器的實驗與理論之U值均隨流率增加，在低流量區域其斜率比較大，而當流量變大之後，斜率減小而漸近水平，整體數據與理論模式結果相當，最大誤差在15%以內。
針對實驗所使用之殼管式試件之尺寸及結構，以採用既有之理論模式如，Kern、Taborek及Bell-Delaware等公式加以模擬，並與實驗結果對照，初步結果顯示，U值隨流率之增加而變大，尤其在小流率區域更為顯著。
而在殼管式熱交換器實驗中，在殼側與管側皆用低流率的時候，所得到的總括熱傳係數與利用Kern Method接近，隨著流率慢慢增加，當在高流率的時候，其實驗數據與理論模擬所得到的總括熱傳係數非常接近，在平均後所得到數值高，整體而言此實驗數據所得到總括熱傳係數與Kern較接近。

關鍵字：體積流率、板式熱交換器、殼管式熱交換器、總括熱傳係數

Abstract

In this paper, the thermal characteristics of heat exchangers are studied. The test facility includes two water tanks which were well insulated and the hot and cold streams were pumped to flow through the test heat exchanger. The flow rates and the temperature at the inlet and exit of hot and cold streams are recorded to calculate the overall heat transfer coefficient.

Both of the shell-and-tube and plate heat exchangers are tested by varying flow rates at different operating temperatures. The results are made to compare with theoretical prediction. In the runs of plate heat exchanger, the overall heat transfer coefficient increases with flow rate especially in the low flow rate regime. The differences between theory and experiments are within 15%.

During the analyses of shell-and-tube heat exchanger, the theories from Kern, Taborek and Bell-Delaware are all used to validate the data. Same as before, the flow rate increases overall heat transfer coefficient when the flow rate is small. The data at small flow rate is found to match those by Kern method. Whereas they agree well with Taborek’s prediction in the high flow rate region.

Keywords： flow rate、heat exchanger、Plate、Shell-and-Tube、overall heat transfer coefficient.

目 錄

致謝辭 I
摘要 II
ABSTRACT III
目錄 IV
表目錄 VI
圖目錄 VIII
符號說明 X
第一章□熱交換器介紹 1
1-1 前言 1
1-2 文獻回顧 2
1-3 研究目的 3
第二章 殼管式熱交換器基本理論推導 4
2-1 殼管式熱交換器總括熱傳係數計算 4
2-2 對數平均溫差法 6
2-3 熱交換器熱傳薄膜係數 8
2-3-1熱交換器管側流體熱對流係數(hi)計算 8
2-3-2熱交換器殼側流體熱對流係數(ho)計算 11
第三章 板式熱交換器理論計算 15
3-1 板片之構造及板式熱交換器原理 15
3-2 板式熱交換器內部流場安排 16
3-3 板片幾何形狀樣式 17
第四章 實驗量測系統 21
4-1 實驗設備系統介紹 21
4-1-1殼管式熱交換器 29
4-1-2板式熱交換器 30
4-2 實驗方法與步驟 31
第五章 結果與討論 33
5-1 實驗數據分析方法 33
5-2 板式熱交換器 34
5-3 殼管式熱交換器 52
5-4 結果與討論 70
第六章 結論 73
參考文獻 75

參考文獻

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