螺旋管熱交換器殼側熱傳特性研究

螺旋管熱交換器結構簡單、製作容易，其原理係利用螺旋曲率造成離心力作用產生二次流效應，增強其對流熱傳效果。目前廣泛應用於熱水熱交換器。其熱傳特性與螺旋圈徑、螺旋管圈節距、管圈數、曲率比等參數有關。文獻當中大多數為討論螺旋管熱交換器在固定高度下所變化的圈數、雷諾數(Reynolds Number)或螺旋管節距與不同的散熱面積下的螺旋管熱交換器之熱傳特性研究。在固定熱傳面積下，探討熱傳特性與上述相關參數的關係，則鮮少相關研究。因此，本文針對螺旋管熱交換器在固定熱傳面積下改變其螺旋圈徑、圈數、螺旋管節距與不同高度，進行其熱傳特性研究。在實驗過程中使用威爾森繪圖法計算殼側熱傳對流係數，經不準確定性分析計算其螺旋管熱交換器之誤差值δℎ표표在20.351 %以內。實驗結果顯示，螺旋管熱交換器之特傳特性與眾多參數相關，其中螺旋圈徑、曲率比、螺旋管節距等參數都將對螺旋管熱交換器之特傳特性具有重大之影響。例如增加其螺旋圈徑時，會導致離心力與壓降降低，使得熱傳特性降低。而增加曲率比、螺旋管圈節距時，會導致二次流效應的增強和增加螺旋管之散熱區域，使得熱傳熱傳性能較佳。

關鍵字

螺旋管式熱交換器；迪恩數；威爾森繪圖法；熱泵熱水器；雷諾數；對數平均溫差

並列摘要

Helical-coil heat exchanger has many features on its applications, such as simple construction, easy manufacturing, and so on. Owing to its higher heat transfer performance than straight tube, caused by second-flow effect through curvature motion, helical-coil heat exchanger, recently, has been widely used in water heating purpose, like heat pump water heater. Many researches have been found to focus on the heat transfer performance related to coil number, Reynolds number, and coil pitch, under fixed coil height. There is rare study to investigate those relationships mentioned above under fixed heat transfer area. In the fixed heat transfer area to explore the relationship between the heat transfer characteristics associated with the above parameters, rarely related research.In additions, the over-all heat transfer performance will have been leaned to be dominated by the coil outside conditions since the main heat transfer resistance exists on shell-side. Therefore, this thesisis interested in focusing on the shell-side heat transfer performance study by experimental method under various coil diameters, coil numbers, coil pitches, and coil heights while restricting on the same heat transfer area. In the experiment, the Wilson-plot method was employed to estimate the shell-side heat transfer coefficient,oh. The uncertainty of the measured oh was also estimated around %351.20less than. The results show that the shell-side heat transfer coefficient,oh, is strongly related to coil diameter, coil pitch, coil curvature, and the Reynolds number.For example, its helical coil diameter increases, the centrifugal force will lead to lower pressure drop, making the heat transfer characteristics is reduced. Increased curvature than when Spiral pitch, will lead the region to enhance and increase the cooling coil of the secondary flow effects, so that the heat transfer performance of heat better.

並列關鍵字

Helical heat exchangers ； Dean Number ； Wilson-plot Method ； Heat Pump Water Heater ； Reynolds Number ； LMTD

參考文獻

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國際替代計量

螺旋管熱交換器殼側熱傳特性研究

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