竖直槽道内蒸气向上流动凝结换热的实验研究
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摘要
通过高速摄影仪拍摄手段,观察了制冷剂R410A蒸气在水力直径为14.34mm、长度为160mm的竖直矩形槽道内垂直向上流动凝结过程中壁面液膜的流动特征.实验结果表明:在饱和温度为28℃和质量流速范围为1.8~23kg·m~(-2)·s~(-1)实验条件下,随着质量流速的增大,壁面出现假滴状流动和层流波状流动,并且随着质量流速的增大凝结液膜逐渐增厚,液膜表面波动亦更加明显;槽道内的平均凝结换热系数随质量流速的增大出现先增大后减小的趋势.实验得到了槽道壁面测温点分割出的四段壁面的各段的平均凝结换热系数的沿槽道轴向的变化情况.
The liquid film flowing characteristics of new refrigerant R410 A flowing upward condensation in a vertical rectangular channel were observed by high speed camera. The saturation temperature of refrigerant R410 A vapor is 28℃. The hydraulic diameter of the rectangular channel is 14. 34 mm and the length is 160 mm. The test was conducted at mass fluxes 1. 8 ~ 23kg·m~(-2)·s~(-1).It is shown that tadpole flow and laminar wave flow occurred with the increase of mass flux.The thickness of the liquid film and the wave frequency were found to be increased and enhanced with increasing mass flux. The average condensation heat transfer coefficient increases at first,and then decreases with mass flux.Also,the variation of the average condensation heat transfer coefficients of the different segments divided by the temperature measuring points with the different segments of the channel were obtained.
The liquid film flowing characteristics of new refrigerant R410 A flowing upward condensation in a vertical rectangular channel were observed by high speed camera. The saturation temperature of refrigerant R410 A vapor is 28℃. The hydraulic diameter of the rectangular channel is 14. 34 mm and the length is 160 mm. The test was conducted at mass fluxes 1. 8 ~ 23kg·m~(-2)·s~(-1).It is shown that tadpole flow and laminar wave flow occurred with the increase of mass flux.The thickness of the liquid film and the wave frequency were found to be increased and enhanced with increasing mass flux. The average condensation heat transfer coefficient increases at first,and then decreases with mass flux.Also,the variation of the average condensation heat transfer coefficients of the different segments divided by the temperature measuring points with the different segments of the channel were obtained.
引文
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[14]胡申华,严俊杰,王进仕.Marangoni凝结形态的影响因素[J].化工学报,2011,62(11):3053-3059Hu Shenhua,Yan Junjie,Wang Jinshi.Affecting factors of Marangoni condensation mode[J].Journal of Chemical Industry and Engineering,2011,62(11):3053-3059
[15]Miyara A.Numerical analysis on flow dynamics and heat transfer of falling liquid films with interfacial waves[J].Heat and Mass Transfer,1999,35(4):298-306
[16]李斌,赵建福,周芳德,等.环形窄通道内流动沸腾换热及两相流型研究[J].应用基础与工程科学学报,2003,11(1):59-64Li Bin,Zhao Jianfu,Zhou Fangde,et al.Study of flow boiling and two-phase flow patterns in narrow-gap annular tube[J].Journal of Basic Science and Engineering,2003,11(1):59-64
[2]Xu Wenyun,Jia Li.Visualization on flow patterns during condensation of 410A in a vertical rectangular channel[J].Journal of Thermal Science,2014,23(3):269-274
[3]杜小泽,王补宣.蒸气在倾斜细小直径圆管内的流动凝结换热特性[J].工程热物理学报,2001,6(22):713-716Du Xiaoze,Wang Buxuan.Condensation heat transfer characteristics for vapor flow inside along small/min-diameter tubes[J].Journal of Engineering Thermophysics,2001,6(22):713-716
[4]李扬,严俊杰,乔磊,等.水-酒精混合物的管外凝结[J].化工学报,2007,58(12):2986-2993Li Yang,Yan Junjie,Qiao Lei,et al.Condensation of water-ethanol mixture on vertical tubes[J].Journal of Chemical Industry and Engineering,2007,58(12):2986-2993
[5]张俊霞,王立,李运刚,等.界面剪切力对蒸汽垂直下流膜状凝结传热的影响分析[J].化工学报,2011,62(10):2733-2739Zhang Junxia,Wang Li,Li Yungang,et al.Analysis of interfacial shear stress effect on vapor downward condensation heat transfer[J].Journal of Chemical Industry and Engineering,2011,62(10):2733-2739
[6]王补宣,杜小泽.细竖管内流动凝结液膜的稳定性分析[J].化工学报,2000,51(1):7-10Wang Buxuan,Du Xiaoze.Stability analysis of film during flow condensation in vertical small diameter tube[J].Journal of Chemical Industry and Engineering,2000,51(1):7-10
[7]Mouza A A,Paras S V,Karabelas A J.Visual observations of flooding in inclined small diameter tubes[C].Proceedings of 3rd European Thermal Sciences Conference.Heidelberg,Germany,2000:1041-1046
[8]李希川,孙中宁.竖直窄矩形流道液泛研究[J].哈尔滨工程大学学报,2012,1(33):42-46Li Xichuan,Sun Zhongning.Study of flooding in vertical narrow rectangular channels[J].Journal of Harbin Engineering University,2012,1(33):42-46
[9]袁达忠,马学虎,房正.两相闭式热虹吸管的流动与传热特性研究[J].高校化学工程学报,2008,22(4):557-562Yuan Dazhong,Ma Xuehu,Fang Zheng.Fluid flow and heat transfer characteristics of a two-phase closed thermosyphon[J].Journal of Chemical Engineering of Chinese Universities,2008,22(4):557-562
[10]Gross U,Philipp C.Conjugated shear stress and Prandtl number effects on reflux condensation heat transfer inside a vertical tube[J].International Journal of Heat and Mass Transfer,2006,49(6):144-153
[11]Gross U,Storch Th,Philipp C,et al.Wave frequency of falling liquid films and the effect on reflux condensation in vertical tubes[J].International Journal of Multiphase Flow,2009,35:398-409
[12]Thumm S,Philipp Ch.U Film condensation of water in a vertical tube with countercurrent vapor[J].International Journal of Heat and Mass Transfer,2001,44:4245-4256
[13]廖强,顾扬彪,朱恂,等.梯度表面能材料表面上滴状凝结换热[J].化工学报,2007,58(3):567-573Liao Qiang,Gu Yangbiao,Zhu Xun,et al.Dropwise condensation heat transfer on surface with gradient surface energy[J].Journal of Chemical Industry and Engineering,2007,58(3):567-573
[14]胡申华,严俊杰,王进仕.Marangoni凝结形态的影响因素[J].化工学报,2011,62(11):3053-3059Hu Shenhua,Yan Junjie,Wang Jinshi.Affecting factors of Marangoni condensation mode[J].Journal of Chemical Industry and Engineering,2011,62(11):3053-3059
[15]Miyara A.Numerical analysis on flow dynamics and heat transfer of falling liquid films with interfacial waves[J].Heat and Mass Transfer,1999,35(4):298-306
[16]李斌,赵建福,周芳德,等.环形窄通道内流动沸腾换热及两相流型研究[J].应用基础与工程科学学报,2003,11(1):59-64Li Bin,Zhao Jianfu,Zhou Fangde,et al.Study of flow boiling and two-phase flow patterns in narrow-gap annular tube[J].Journal of Basic Science and Engineering,2003,11(1):59-64