异形管束降膜流动流型及波长的分布规律
|
摘要
采用可视化方法对水的降膜流动过程进行了实验研究,考察了两异形管(蛋形管和滴形管)管间流型及其转变、降膜波长随Re数和管型的分布规律,并与圆管进行了对比分析。实验结果表明:各管的管间流型均随Re数的增大依次呈现滴状流、滴柱状流、柱状流、柱片状流和片状流;相较于圆管,两异形管的各流型更易在较低的Re数下获得,且流型较稳定。随着Re数增加和管间距S的降低,降膜波长呈减小趋势。两异形管的降膜波长较圆管的低,且蛋形管的流型转变Re数最低。
The aim of the present study is to investigate the effect of the tube type,Reynolds number and intertube spacing on the falling film modes and dimensionless wavelength for oval- and drop-shaped tube by a visualization experimental study.Then,a comparison between circular tube and the two shaped tubes was conducted.The experimental results show that the flow modes between the tubes can be observed:discrete droplets,drop-jet,liquid jet,jet-sheet,or continuous liquid sheet for all the test tubes with the increase of Reynolds number.Compared with the circular tube,the more stable flow modes of the shaped tubes can be obtain at a lower Reynolds number.Under the conditions of this study,the falling wavelength decreases with the increase of Reynolds number and the decrease of intertube spacing.The study found that the falling wavelength of the shaped tubes is smaller than that of the circular tube and the Reynolds number of mode transition of the oval-shaped tube is smallest.
The aim of the present study is to investigate the effect of the tube type,Reynolds number and intertube spacing on the falling film modes and dimensionless wavelength for oval- and drop-shaped tube by a visualization experimental study.Then,a comparison between circular tube and the two shaped tubes was conducted.The experimental results show that the flow modes between the tubes can be observed:discrete droplets,drop-jet,liquid jet,jet-sheet,or continuous liquid sheet for all the test tubes with the increase of Reynolds number.Compared with the circular tube,the more stable flow modes of the shaped tubes can be obtain at a lower Reynolds number.Under the conditions of this study,the falling wavelength decreases with the increase of Reynolds number and the decrease of intertube spacing.The study found that the falling wavelength of the shaped tubes is smaller than that of the circular tube and the Reynolds number of mode transition of the oval-shaped tube is smallest.
引文
[1]Ribatski G,Jacobi A M.Falling-Film Evaporation on Horizontal Tubes-a Critical Review[J].International Journal of Refrigeration-Revue Internationale Du Froid,2005,28(5):635-653
[2]Ghien L-H,Tsai Y-L.An Experimental Study of Pool Boiling and Falling Film Vaporization on Horizontal Tubes in R-245fa[J].Applied Thermal Engineering,2011,31(17/18):4044-4054
[3]齐春华,李炎,俞永江,等.水平管降膜蒸发海水淡化的传热试验研究[J].化学工业与工程,2011,28(5):1-5,14QI Chunhua,LI Yan,YU Yongjiang,el al.Experimental Study on Heat-Transfer Coefficients of Horizontal Tube Falling-Film Evaporation Equipment[J].Chemical Industry and Engineering,2011,28(5):1-5,14
[4]Hu X,Jacobi A M.The Intertube Falling Film Part 1:Flow Characteristics,Mode Transitions and Hysteresis[J].ASME J Heat Transfer,1996,118(3):616-625
[5]Hu X,Jacobi A M.The Intertube Falling Film Part 2:Mode Effects on Sensible Heat Transfer to a Falling Liquid Film[J].ASME J Heat Transfer,1996,118(3):626-633
[6]Mitrovic J,Influence of Tube Spacing and Flow Rate on Heat Transfer From a Horizontal Tube to a Falling Liquid Film[C]//Proceedings of the 8th International Heat Transfer Conference,1986:1949-1956
[7]Lienhard J H,Wong P T Y.The Dominant Unstable Wavelength and Minimum Heat Flux During Fillm Boiling on a Horizontal Cylinder[J].Journal of Heat Transfer,1964,86(2):220-226
[8]Mohamed AMI.Flow Behavior of Liquid Falling Film on a Horizontal Rotating Tube[J].Experimental Thermal and Fluid Science,2007,31(4):325-332
[9]Maron-Moalem D,Sideman S,Dukler A E.Dripping Characteristics in a Horizontal Tube Film Evaporator[J].Desalination,1978,27(2):117-127
[10]Armbruster R,Mitrovic J.Heat Transfer in Falling Film on a Horizontal Tube[J].ASME-PUBLICATIONS-HTD,1995,314(1):13-22
[11]罗林聪,张冠敏,田茂诚,等.异形管降膜传热与流动数值模拟研究[J].工程热物理学报,2013,34(4):710-714LUO Lincong,ZHANG Guanmin,TIAN Maocheng,el at.Numerical Simulation of Liquid Film Flow on Horizontal Circular and Shaped Cylinders for Falling Film Evaporation[J].Journal of Engineering Thermophysics,2013,34(4):710-714
[12]LUO Lincong,ZHANG Guanmin,PAN Jihong,el at.Flow and Heat Transfer Characteristics of Falling Water Film on Horizontal Circular and Non-Circular Cylinders[J].Journal of Hydrodynamics,Ser B,2013,25(3):404-414
[13]Hu X,Jacobi A M.Departure-Site Spacing for Liquid Droplets and Jets Falling Between Horizontal Circular Tubes[J].Experimental Thermal and Fluid Science,1998,16(4):322-331
[14]吕凯,王小飞,张颖,等.水平蒸发管管间相邻液柱分离间距测量[J].化工学报,2012,63(3):740-745LV Kai,WANG Xiaofei,ZHANG Ying,el at.DepartureSite Spacing for Horizontal Liquid Columns Falling Between Circular Tubes[J].CIESC Joural,2012,63(3):740-745
[2]Ghien L-H,Tsai Y-L.An Experimental Study of Pool Boiling and Falling Film Vaporization on Horizontal Tubes in R-245fa[J].Applied Thermal Engineering,2011,31(17/18):4044-4054
[3]齐春华,李炎,俞永江,等.水平管降膜蒸发海水淡化的传热试验研究[J].化学工业与工程,2011,28(5):1-5,14QI Chunhua,LI Yan,YU Yongjiang,el al.Experimental Study on Heat-Transfer Coefficients of Horizontal Tube Falling-Film Evaporation Equipment[J].Chemical Industry and Engineering,2011,28(5):1-5,14
[4]Hu X,Jacobi A M.The Intertube Falling Film Part 1:Flow Characteristics,Mode Transitions and Hysteresis[J].ASME J Heat Transfer,1996,118(3):616-625
[5]Hu X,Jacobi A M.The Intertube Falling Film Part 2:Mode Effects on Sensible Heat Transfer to a Falling Liquid Film[J].ASME J Heat Transfer,1996,118(3):626-633
[6]Mitrovic J,Influence of Tube Spacing and Flow Rate on Heat Transfer From a Horizontal Tube to a Falling Liquid Film[C]//Proceedings of the 8th International Heat Transfer Conference,1986:1949-1956
[7]Lienhard J H,Wong P T Y.The Dominant Unstable Wavelength and Minimum Heat Flux During Fillm Boiling on a Horizontal Cylinder[J].Journal of Heat Transfer,1964,86(2):220-226
[8]Mohamed AMI.Flow Behavior of Liquid Falling Film on a Horizontal Rotating Tube[J].Experimental Thermal and Fluid Science,2007,31(4):325-332
[9]Maron-Moalem D,Sideman S,Dukler A E.Dripping Characteristics in a Horizontal Tube Film Evaporator[J].Desalination,1978,27(2):117-127
[10]Armbruster R,Mitrovic J.Heat Transfer in Falling Film on a Horizontal Tube[J].ASME-PUBLICATIONS-HTD,1995,314(1):13-22
[11]罗林聪,张冠敏,田茂诚,等.异形管降膜传热与流动数值模拟研究[J].工程热物理学报,2013,34(4):710-714LUO Lincong,ZHANG Guanmin,TIAN Maocheng,el at.Numerical Simulation of Liquid Film Flow on Horizontal Circular and Shaped Cylinders for Falling Film Evaporation[J].Journal of Engineering Thermophysics,2013,34(4):710-714
[12]LUO Lincong,ZHANG Guanmin,PAN Jihong,el at.Flow and Heat Transfer Characteristics of Falling Water Film on Horizontal Circular and Non-Circular Cylinders[J].Journal of Hydrodynamics,Ser B,2013,25(3):404-414
[13]Hu X,Jacobi A M.Departure-Site Spacing for Liquid Droplets and Jets Falling Between Horizontal Circular Tubes[J].Experimental Thermal and Fluid Science,1998,16(4):322-331
[14]吕凯,王小飞,张颖,等.水平蒸发管管间相邻液柱分离间距测量[J].化工学报,2012,63(3):740-745LV Kai,WANG Xiaofei,ZHANG Ying,el at.DepartureSite Spacing for Horizontal Liquid Columns Falling Between Circular Tubes[J].CIESC Joural,2012,63(3):740-745