臺灣博碩士論文加值系統

本文在於研究水與空氣在石英管內(管徑6.7mm&管徑2.7mm)流動，在管內徑6.7mm&管內徑2.7mm時，它的曲徑比( )有3和 7，總質通量為100~700 ，模擬冷煤在熱交換器上三叉管在不同質通量(G)、不同乾度下(x)，上下管是以何種流型流動，及探討流量分佈的情形，兩項流的一些現象，像流體的逆流、塊狀流及“freezing slug”都可在本篇的 的垂直三叉彎管中觀察得到，然而這個流體的逆流和凍結塊狀流現象在小管徑 卻是很難看到的，那是因為流體慣性力和表面張力的影響。在相同的質通量及乾度下，在 時其兩相流譜從入口管到分叉管變化很小，而在D=6.7mm則流譜則有很大變化。
在流量分佈方面，在 的流入上下垂直分叉管的流量是和流型變化有直接的關係，由於重力的影響流入下管的水流量總是比上管流量多，相較之下 時在相同的質通量及乾度下，其流量分佈並沒有像 那樣上下管流量差異很大，而是呈現上下管流量比較接近的現象。

The split U-type junctions are commonly utilized in the condensers and evaporators of refrigeration systems. After splitting through a U-type junction, a maldistribution of the phases may occur when the flow resistances in both legs are not equal. Accordingly the flow pattern change is expected very complex within the U-type junction and the flow pattern in the two legs downstream will not be the same as the upstream. This study is to conduct a series air-water two-phase flow tests in two vertical U-type glass junctions to observe the pattern distribution in the presence of U-type junction subjected to different tube diameters and radiuses of curvature at different operating conditions of mass flux and quality. The flow rates at the upper and lower tubes after the junction are also measured to investigate the effects of the gravity and two-phase flow pattern to the flow rate distribution.
Four tubes with the presence of two split U-type Junctions have 6.7 mm and 2.7 mm diameters (D) with two curvature ratios (2R/D) of 3 and 7 are utilized for tests. The total mass flux (G) is ranged from 100 to 700 kg/m2�泅 and quality (x) is changed from 0.001 to 0.5. The flow rate distribution between the upper and lower tubes is found greatly related to the flow pattern (which is affected by G and x), tube diameter (since surface tension has great influence on the smaller diameter tube), and curvature radius (which is related to the gravity force due to the height)
Two- phase flow phenomenon, such as flow reversal, slug of intermittent and " freezing slug " can observe getting in vertical split u-type junction at D = 6.7mm of this study, but the flow reversal and freezing slug are very difficult to observe in the small diameter tube (D = 2.7mm), due to the influence of the flow inertia and surface tension . Under the same mass flux and the quality, two phase flow pattern of small diameter tube (D = 2.7) has few changes from the entering tube to the two dividing tubes, however, there has large flow pattern changes in the split U junction of D = 6.7mm.
For D = 6.7 mm, higher flow rate into the lower tube after the U junction and smaller flow rate into the upper tube are observed due to the higher influence of gravity. However, the flow distribution into the lower and upper tubes becomes more closed for D = 2.7 mm at the same mass flux and the quality of D = 6.7 mm because the surface tension has greater influence than the gravity force on small tube.

第一章 緒論
第二章 文獻回顧
第三章 實驗系統與分析方法
第四章 結果與討論
第五章 結論

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黃弼釤，2003，“空氣和水兩相留在垂直U型管內流譜拍攝與分析”，國立雲林科技大學 機械工程學系碩士論文