新疆大学学报（自然科学版）
新疆大學學報（自然科學版）
신강대학학보（자연과학판）
XINJIANG UNIVERSITY JOURNAL(NATURAL SCIENCE EDITION)
2014年
3期
352-357
,共6页
水-酒精混合蒸气%凝结换热%Marangoni效应
水-酒精混閤蒸氣%凝結換熱%Marangoni效應
수-주정혼합증기%응결환열%Marangoni효응
ethanol-water mixture%condensation heat transfer%Marangoni effect
本文搭建了水平圆管管外凝结传热实验台，以水-酒精混合蒸气为工质，在不同蒸气压力和不同酒精浓度的条件下对水平圆管外凝结换热特性进行了研究，并实现了实验的可视化，分析了不同酒精浓度下造成凝结换热特性差异的原因。实验结果表明：凝结表面不同位置的传热系数不同，表面张力梯度大的位置凝结传热系数较大。在相同流速和浓度条件下，酒精浓度较低时凝结传热系数随蒸气压力的升高而升高，但在高酒精浓度下，凝结液表面张力梯度减小、扩散热阻的影晌增大，蒸气压力对于凝结传热系数的影响并不明显。酒精浓度对凝结传热系数的影响因不同横截面测温点有明显差异，在浓度为2%和5%时传热系数差异较大，而在其他浓度时横截面不同测点的凝结换热效果差异较小。
本文搭建瞭水平圓管管外凝結傳熱實驗檯，以水-酒精混閤蒸氣為工質，在不同蒸氣壓力和不同酒精濃度的條件下對水平圓管外凝結換熱特性進行瞭研究，併實現瞭實驗的可視化，分析瞭不同酒精濃度下造成凝結換熱特性差異的原因。實驗結果錶明：凝結錶麵不同位置的傳熱繫數不同，錶麵張力梯度大的位置凝結傳熱繫數較大。在相同流速和濃度條件下，酒精濃度較低時凝結傳熱繫數隨蒸氣壓力的升高而升高，但在高酒精濃度下，凝結液錶麵張力梯度減小、擴散熱阻的影晌增大，蒸氣壓力對于凝結傳熱繫數的影響併不明顯。酒精濃度對凝結傳熱繫數的影響因不同橫截麵測溫點有明顯差異，在濃度為2%和5%時傳熱繫數差異較大，而在其他濃度時橫截麵不同測點的凝結換熱效果差異較小。
본문탑건료수평원관관외응결전열실험태，이수-주정혼합증기위공질，재불동증기압력화불동주정농도적조건하대수평원관외응결환열특성진행료연구，병실현료실험적가시화，분석료불동주정농도하조성응결환열특성차이적원인。실험결과표명：응결표면불동위치적전열계수불동，표면장력제도대적위치응결전열계수교대。재상동류속화농도조건하，주정농도교저시응결전열계수수증기압력적승고이승고，단재고주정농도하，응결액표면장력제도감소、확산열조적영상증대，증기압력대우응결전열계수적영향병불명현。주정농도대응결전열계수적영향인불동횡절면측온점유명현차이，재농도위2%화5%시전열계수차이교대，이재기타농도시횡절면불동측점적응결환열효과차이교소。
In this article the effects of vapor pressure, vapor concentration on the condensation heat transfer characteristics of ethanol-water mixture vapor on horizontal tube were investigated experimentally. Visual results were showed in this experiment. In order to clarify the heat transfer characteristics of vary ethanol vapor concentrations, heat flux and vapor-to-surface temperature difference were measured. The results demonstrate that the local heat transfer coefficients at different locations on condensing surface were different, and at the local position with greater tension gradient the heat transfer coefficient was higher. On the same condition of vapor concentration and speed, heat transfer coefficients of high pressure are bigger than those of low pressure in the low-ethanol concentration range. But the effect of vapor pressure on the heat transfer coefficients is not obvious in the high -ethanol concentration range. The reason for this is that bigger diffusion resistance and the gradient of the surface tension versus the condensation mass fraction becomes smaller with the increase in vapor concentration. It has been found that different concentration of ethanol in the liquid phase has significant influence on heat transfer coefficients on different cross section thermocouples. The D-value of heat transfer coefficients are greater when ethanol composition is 2% and 5%, and lower in other composition at different position in the same circumstance.
