Condensation heat transfer characteristic and flow pattern of steam in rectangular tube with different aspect ratio

doi:10.11949/j.issn.0438-1157.20180253

Abstract

Abstract:

An investigation on single side condensation of vapor inside a horizontal rectangular tube was performed. The influences of tube aspect ratio on flow pattern, heat transfer coefficient and pressure drop were analyzed. Annular flow, annular-wave flow, wave flow, slug flow, plug flow and bubbly flow are observed. Flow pattern appearing in larger aspect ratio tube was more comprehensive than in small one. The area occupied by the annular flow increased with the decrease of the aspect ratio, but the difference gradually decreases with the increase of mass flow rates. Heat transfer coefficient and pressure drop increased with aspect ratio decreased while mass flow rate was small. With the mass flow rate increased, the difference for heat transfer coefficient decreased while for pressure drop increased.

Key words: rectangular tube, aspect ratio, flow pattern, condensation, heat transfer

摘要：

通过可视化流型观测及实验测量，研究了单边换热矩形小通道的高宽比对两相流型、平均冷凝传热系数及两相流动阻力的影响，采用高速摄像机拍摄了环状流、环波状流、波状流、弹状流、塞状流及泡状流6种典型流型。研究表明，高宽比为1：2及1：3的通道内出现流型种类较为全面，而在高宽比为1：5通道内基本无弹状流、塞状流及泡状流。1：5通道内环状流所占区域较1：2及1：3通道大，随入口蒸汽质量流速的增加，差值逐步减小。随着通道高宽比的减小，平均冷凝传热系数逐渐增大；不同高宽比通道中平均冷凝传热系数间的差值随入口蒸汽质量流速的增加而减小；蒸汽质量流速足够高时，高宽比对传热系数基本无影响。通道内两相流压降随通道高宽比的减小而增大；随着入口蒸汽质量流速的增加，不同比例通道内的两相流动压降差距逐渐增大。

关键词: 矩形通道, 高宽比, 流型, 凝结, 传热

CLC Number:

TS734
TK124

YAN Yan, DONG Jixian. Condensation heat transfer characteristic and flow pattern of steam in rectangular tube with different aspect ratio[J]. CIESC Journal, 2018, 69(9): 3851-3858.

严彦, 董继先. 高宽比对矩形通道内蒸汽冷凝传热特性及流型影响的研究[J]. 化工学报, 2018, 69(9): 3851-3858.

References 30

[1]	STENSTRÖM S, SVANQUIST T. A general model for calculating pressure drop in siphons and siphon riser tubes(Ⅰ):Principles and theoretical model[J]. Tappi Journal, 1991, 14(2):46-53.
[2]	STENSTRÖM S, SVANQUIST T. A general model for calculating pressure drop in siphons and siphon riser tubes(Ⅱ):Experimental results[J]. Tappi Journal, 1991, 15(1):23-31.
[3]	CHOI S U S, YU W, FRANCE D M, et al. A novel multiport cylinder dryer[J]. Tappi Journal, 2001, 84(2):73-79.
[4]	WANG J C Y, QIU L J, WANG S F. Enhanced condensation inside a horizontal rotating drum-dryer[J]. Drying Technology, 1990, 8(4):829-843.
[5]	HALL D B, MONROE J F, TIMM G L. Application of stationary and rotary siphons[J]. Tappi Journal, 1993, 76(8):97-105.
[6]	MEYER F, MEYERHOFMEISTER E. Accretion disk evaporation by a coronal siphon flow[J]. Astronomy & Astrophysics, 1994, 288(1):175-182.
[7]	CALKINS D L. The effects of syphon clearance on dryer performance:Johnson technical papers[R]. Three Rivers, MI:The Johnson Corp., 1992.
[8]	APPEL D W, HONG S H. Optimizing heat-transfer using bars in dryers[J]. Paper Technology and Industry, 1975, 16(4):264-269.
[9]	HERRO H, BRUSCATO R. Failure of zinc-plated self-tapping screws and belleville washers used to install spoiler bars in cast iron dryers[J]. Nature Communications, 1999, 4(3):134-143.
[10]	Gregory L Wedel, 单翔年. 扰流棒在提高热传导性能和冷凝水排出过程中的作用[J]. 中华纸业, 2009, 30(10):105-108. WEDEL G L, SHAN X N. The effect of turbulence bar in increasing heat conduction performance and condensate discharge[J]. China Pulp & Paper Industry, 2009, 30(10):105-108.
[11]	YU W, CHOI S U S, FRANCE D M, et al. Single-sided steam condensing inside a rectangular horizontal channel[J]. International Journal of Heat and Mass Transfer, 2002, 45(1):3715-3724.
[12]	CHOI S U. Multiport cylinder dryer with low thermal resistance and high heat transfer:US 6397489B1[P]. 2002-08-12.
[13]	LABORATORY A N, KADANT J. Multiport dryer technology breakthrough dryer technology will greatly improve papermaking efficiency[R]. Washington:Department of Energy Efficiency and Renewable Energy Industrial Technologies Program, 2006.
[14]	PARK K J, JUNG D S, SEO T. Flow condensation heat transfer characteristics of hydrocarbon refrigerants and dimethyl ether inside a horizontal plain tube[J]. International Journal of Multiphase Flow, 2008, 34(7):628-635.
[15]	邢玉雷. 真空水平管内蒸汽凝结换热实验研究[D]. 大连:大连理工大学, 2008. XING Y L. Experimental study of condensation and heat transfer in vacuum horizontal tubes[D]. Dalian:Dalian University of Technology, 2008.
[16]	顾红芳, 陈听宽, 孙丹. 煤油和空气的混合物水平管内冷凝换热[J]. 化工学报, 2002, 53(3):313-316. GU H F, CHEN T K, SUN D. Investigation of condensation heat transfer of kerosene-air mixtures in horizontal tube[J]. Journal of Chemical Industry and Engineering (China), 2002, 53(3):313-316.
[17]	CHINNOV E A, RONSHIN F V, KABOV O A. Two-phase flow patterns in short horizontal rectangular microchannels[J]. International Journal of Multiphase Flow, 2015, 80:57-68.
[18]	徐慧强, 孙中宁, 谷海峰, 等. 水平管内纯饱和蒸汽强制对流冷凝局部换热特性[J]. 化工学报, 2015, 66(1):92-98. XU H Q, SUN Z N, GU H F, et al. Local heat transfer characteristics of saturated steam forced convection condensation inside horizontal tube[J]. CIESC Journal, 2015, 66 (1):92-98.
[19]	WANG Y, MU X, SHEN S, et al. Heat transfer characteristics of steam condensation flow in vacuum horizontal tube[J]. International Journal of Heat and Mass Transfer, 2017, 108(2):128-135.
[20]	CHEN Y, WU R, SHI M, et al. Visualization study of steam condensation in triangular microchannels[J]. International Journal of Heat & Mass Transfer, 2009, 52(21):5122-5129.
[21]	CAVALLINI A, CENSI G, DEL COLA D, et al. Experimental investigation on condensation heat transfer and pressure drop of new HFC refrigerants (R134a, R125, R32, R410A, R236ea) in a horizontal smooth tube[J]. International Journal of Refrigeration, 2001, 24(1):73-87.
[22]	JUNG D S, SONG K H, CHO Y G, et al. Flow condensation heat transfer coefficients of pure refrigerants[J]. International Journal of Refrigeration, 2003, 26(1):4-11.
[23]	APREA C, GRECO A, VANOLI G P. Condensation heat transfer coefficients for R22 and R407C in gravity flow regime within a smooth horizontal tube[J]. International Journal of Refrigeration, 2003, 26(4):393-401.
[24]	马志先, 张吉礼, 孙德兴. HFC245fa水平光管与强化管管束外冷凝换热[J]. 化工学报, 2010, 61(5):1097-1106. MA Z X, ZHANG J L, SUN D X. Condensation heat transfer coefficient of H FC245fa on horizontal smooth and enhanced tube bundles[J]. CIESC Journal, 2010, 61(5):1097-1106.
[25]	杨英英, 李敏霞, 马一太. 水平光滑细管内R32冷凝换热的流型特性[J]. 化工学报, 2014, 65(2):445-452. YANG Y Y, LI M X, MA Y T. Characteristics of flow pattern for condensation heat transfer of R32 in horizontal small tube[J]. CIESC Journal, 2014, 65 (2):445-452.
[26]	SARMADIAN A, SHAFAEE M, MASHOUF H, et al. Condensation heat transfer and pressure drop characteristics of r-600a in horizontal smooth and helically dimpled tubes[J]. Experimental Thermal & Fluid Science, 2017, 86(4):54-62.
[27]	CHOI S U S, YU W, WAMBSGANSS M W, et al. Design and demonstration of multiport cylinder dryer:final report on the multiport dryer project in phase 1[R]. US:Office of Scientific & Technical Information Technical Reports, 2001.
[28]	SHIN J H, HWANG K S, JANG S P, et al. Flow and thermal characteristics of condensing steam in a single horizontal mini-channel of a multiport cylinder dryer[J]. Drying Technology, 2010, 29(1):47-54.
[29]	YAN Y, DONG J X, TANG W. Visualization study of steam condensation in rectangular channel of multichannel cylinder dryer[J]. Journal of Heat Transfer, 2017, 139(5):197-202.
[30]	KEW P A, CORNWELL K. Correlations for the prediction of boiling heat transfer in small-diameter channels[J]. Applied Thermal Engineering, 1997, 17(8/9/10):705-715.