戊烷液滴群在水中汽化传热的实验研究
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摘要
采用频闪摄影的实验方法研究直接接触汽化传热过程中戊烷液滴群的行为及与传热系数的关系,在研究的基础上总结了戊烷与水直接接触汽化传热的机理。分析了戊烷进口流量、水温、测试高度对戊烷与水液液界面面积的影响,进一步分析了泡滴上升速度、测试高度、戊烷汽化率对戊烷泡滴传热系数的影响。实验结果表明:随着测试高度和水温的增加,液液传热面积逐渐减小,而戊烷的流量增加使得单位体积的传热面积增加;连续相水的剧烈湍动和液液界面的频繁更新使得传热系数增加;流体的混合强度越大,越有利于减小传热热阻,促进水主体与界面水的传热。
The experiment method of stroboscopic photography was used to study the behavior of pentane drobbles and the relationship with the heat transfer coefficient in direct contact with the heat transfer process. The mechanism of pentane-water direct contact evaporation heat transfer was summarized. The influences of pentane inlet flow velocity, water temperature, test height on the surface area of pentane-water liquid-liquid interface and the pentane drobbles rising velocity, test height,pentane vaporization rate on the heat transfer coefficient were analyzed. The results show that the heat transfer area decreases gradually with the increase of test height and water temperature. As the flow rate of pentane increased, the heat transfer area per unit volume increased. The severe turbulence of water and the frequent updating of liquid-liquid interface resulted in the increase of the heat transfer coefficient. The mixing intensity of the liquid was beneficial to reduce heat transfer resistance and promoted the heat transfer of water body and interface water.
The experiment method of stroboscopic photography was used to study the behavior of pentane drobbles and the relationship with the heat transfer coefficient in direct contact with the heat transfer process. The mechanism of pentane-water direct contact evaporation heat transfer was summarized. The influences of pentane inlet flow velocity, water temperature, test height on the surface area of pentane-water liquid-liquid interface and the pentane drobbles rising velocity, test height,pentane vaporization rate on the heat transfer coefficient were analyzed. The results show that the heat transfer area decreases gradually with the increase of test height and water temperature. As the flow rate of pentane increased, the heat transfer area per unit volume increased. The severe turbulence of water and the frequent updating of liquid-liquid interface resulted in the increase of the heat transfer coefficient. The mixing intensity of the liquid was beneficial to reduce heat transfer resistance and promoted the heat transfer of water body and interface water.
引文
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[2] SONG M,STEIFF A,WEINSPACH P M.Direct-contact heat transfer with change of phase:a population balance model[J].Chemical Engineering Science,1999,54(17):3861-3871.
[3] XU J,XIAO Q,FEI Y.Accurate estimation of mixing time in a direct contact boiling heat transfer process using statistical methods[J].International Communications in Heat and Mass Transfer,2016,75:162-168.
[4] HENNATI A,SHIRVANI M,GHAEMI A.A study of drop size distribution and mean drop size in a perforated rotating disc contactor (PRDC)[J].Chemical Engineering Research and Design,2015,96:54-62.
[5] TOCHITANI Y,NAKAGAWA T,MORI Y H.Vaporization of single liquid drops in an immiscible liquid part II:Heat transfer characteristics[J].Warmeund Stoffubertragung,1977,10:71-79.
[6] ZHANG X,DONG H,HUANG Y.Experimental study on gas holdup and bubble behavior in carbon capture systems with ionic liquid[J].Chemical Engineering Journal,2012,209:607-615.