Local void fraction distribution of gas-liquid two-phase flow in rectangular helically coiled channel

doi:10.11949/j.issn.0438-1157.20171411

Abstract

Abstract:

An electric conductivity probe was designed to study local void fraction of gas-liquid two-phase flow in a rectangular helically coiled channel. Reliability of the electric conductivity probe was verified by measuring length of Taylor bubble at various gas superficial velocity and by comparing it to visualization measurement. A suitable threshold value was determined for signal processing. Effects of liquid and gas superficial velocities on local void fraction distribution were investigated at three regimes of bubbly, slug and annular flow. The experimental results show that local void fraction distribution of gas-liquid two-phases in helically coiled channel is asymmetric parabola, which the asymmetry is dependent on flow regime and liquid superficial velocity.

Key words: rectangular helically coiled channel, gas-liquid two-phase flow, electric conductivity probe, local void fraction, bubble

摘要：

应用电导探针测量技术，对矩形截面螺旋通道内气液两相流局部含气率进行实验研究。在不同的气相折算速度下，应用电导探针测量了弹状流弹单元的长度，并与可视化方法进行对比，验证了电导探针的可靠性，并为信号处理选择合适的阈值。分别在泡状流、弹状流及环状流三种流型的条件下，分析了气相与液相折算速度对局部含气率分布的影响。实验结果发现，螺旋通道气液两相局部含气率呈非对称的抛物线形分布，这种非对称性受流型和液相折算速度的影响。

关键词: 矩形截面螺旋通道, 气液两相流, 电导探针, 局部含气率, 气泡

CLC Number:

O359

CAI Bo, XIA Guodong, JIA Yuting, ZHOU Yanzhao, ZONG Luxiang. Local void fraction distribution of gas-liquid two-phase flow in rectangular helically coiled channel[J]. CIESC Journal, 2018, 69(6): 2474-2480.

蔡博, 夏国栋, 贾玉婷, 周燕昭, 宗露香. 矩形截面螺旋通道内气液两相流局部含气率分布实验研究[J]. 化工学报, 2018, 69(6): 2474-2480.

References 30

[1]	HIBIKI T, MI Y, SITU R, et al. Interfacial area transport of vertical upward bubbly two-phase flow in an annulus[J]. Int. J. Heat Mass Tran., 2003, 46:4949-4962.
[2]	MURAI Y, INABA K, TAKEDA Y, et al. Backlight imaging tomography for slug flows in straight and helical tubes[J]. Flow Meas. Instrum., 2007, 18:223-229.
[3]	HUA C, WANG X H, GAO X, et al. Experimental research on the start-up characteristics and heat transfer performance of pulsating heat pipes with rectangular channels[J]. Appl. Therm. Eng., 2017, 126:1058-1062.
[4]	MAEDA A, FUJISAWA N, YAMAGATA T, et al. Characterization of exchange flow in vertical pipes of circular and square cross-sections under unstable density gradient[J]. Int. Commun. Heat Mass, 2017, 82:81-88.
[5]	LIU N, LI J M, SUN J, et al. Heat transfer and pressure drop during condensation of R152a in circular and square microchannels[J]. Exp. Therm. Fluid Sci., 2013, 47:60-67.
[6]	RIPPLE G R, EIDT C M. Two-phase flow in a coiled tubes[J]. Int. Eng. Chem. Proc. Des. Dev., 1996:5(1):32-39.
[7]	XIN R C, AWWAD A. An investigation and comparative study of the pressure drop in air-water two-phase flow in vertical helicoidal pipes[J]. Int. J. Heat Mass Tran., 1996, 39(4):735-743.
[8]	LIU X F, XIA G D, ZHAI Y L, et al. Numerical analysis of two-phase pressure drop and liquid distribution in single screw expander prototype[J]. Chinese Sci. Bull., 2014, 54:4388-4396.
[9]	XU L J, XU W F, CAO Z, et al. Multiple parameters' estimation in horizontal well logging using a conductance-probe array[J]. Flow Meas. Instrum., 2014, 40:192-198.
[10]	周媛. 结构化多相反应器单通道及床层尺度流动与混合特性研究[D]. 北京:北京化工大学, 2011. ZHOU Y. Hydrodynamics and liquid mixing at single channel and whole bed scales in multiphase monolithic reactor[D]. Beijing:Beijing University of Chemical Technology, 2011.
[11]	BARNEA D, ROITBERG E, SHEMER L. Spatial distribution of void fraction in the liquid slug in the whole range of pipe inclinations[J]. Int. J. Mulitiph. Flow, 2013, 52:92-101.
[12]	吕术森, 陈雪莉, 于广锁, 等. 应用电导探针测定鼓泡塔内气泡参数[J]. 化学反应工程与工艺, 2003, 4:344-351. LÜ S S, CHEN X L, YU G S, et al. Study on flow parameter in bubble column with conductivity probe[J]. Chemical Reaction Engineering and Technology, 2003, 4:344-351.
[13]	孙科霞, 陈学俊, 张鸣远, 等. 应用双头电导探针技术测量气液两相泡状流局部参数[J]. 计量学报, 1999, 4:297-303. SUN K X, CHEN X J, ZHANG M Y, et al. Measurement of local bubble flow parameter with dual-conductivity probe[J]. Acta Metrologica Sinica, 1999, 4:297-303.
[14]	韩梅, 沙作良, 伍倩, 等. 双探针电导探头测量气泡参数的信号质量[J]. 过程工程学报, 2009, 9(2):222-227. HAN M, SHA Z L, WU Q, et al. Signal quality of dual-tip electrical conductivity probe for measurement of bubble parameters[J]. The Chinese Journal of Process Engineering, 2009, 9(2):222-227.
[15]	朱姝, 包雨云, 陈雷, 等. 用电导探针测定气-液多层桨搅拌槽内气泡尺寸分布[J]. 高校化学工程学报, 2011, 6(12):977-984. ZHU S, BAO Y Y, CHEN L, et al. Study on bubble length distribution in a stirred tank using a conductivity probe[J]. Journal of Chemical Engineering of Chinese Universities, 2011, 6(12):977-984.
[16]	陈鸥, 杨献勇, 徐光捷. 气液两相流中液相局部速度测量实验[J]. 清华大学学报(自然科学版), 2005, 45(2):238-241. CHEN O, YANG X Y, XU G J. Experimental study on liquid velocity[J]. Journal of Tsinghua University, 2005, 45(2):238-241.
[17]	ZHENG D H, CHE D F. Experimental study on hydrodynamic characteristics of upward gas-liquid slug flow[J]. Int. J. Multiph. Flow, 2006, 32:1191-1218.
[18]	VAN DER WELLE R. Void fraction, bubble velocity and bubble size in two-phase flow[J]. Int. J. Multiph. Flow, 1985, 11 (3):317-345.
[19]	RÜDISÜLI M, SCHILDHAUER T J, BIOLLAZ S M A, et al. Bubble characterization in a fluidized bed by means of optical probes[J]. Int. J. Multiph. Flow, 2012, 41:56-67.
[20]	LIN T J, BANKOFF S G. Structure of air-water bubbly flow in a vertical pipe-Ⅰ, Ⅱ[J]. Int. J. Heat Mass Tran., 1993, 7(36):1049-1072.
[21]	HIBIKI T, MI Y, SITU R, et al. Interfacial area transport of vertical upward bubbly two-phase flow in an annulus[J]. Int. J. Heat Mass Tran., 2003, 46:4949-4962.
[22]	ZHAI L S, BIAN P, GAO Z K, et al. The measurement of local flow parameters for gas-liquid two-phase bubbly flows using a dual-sensor probe array[J]. Chem. Eng. Sci., 2016, 144:346-363.
[23]	TYAGI P, BUWA V V. Experimental characterization of dense gas-liquid flow in a bubble column using voidage probes[J]. Chem. Eng. J., 2017, 308:912-928.
[24]	VIEIRA R E, KESAANA N R, TORRES C F, et al. Experimental investigation of horizontal gas-liquid stratified and annular flow using wire-mesh sensor[J]. J. Fluids Eng., 2014, 136(12):121301.
[25]	WANG X, WANG T J, HE L M. Measurement of gas entrainment from stationary liquid slug in horizontal tube with double-sensor conductivity probe[J]. Flow Meas. Instrum., 2012, 27:81-91.
[26]	PJONTEK D, PARISIEN V, MACCHI A. Bubble characteristics measured using a monofibre optical probe in a bubble column and freeboard region under high gas holdup conditions[J]. Chem. Eng. Sci., 2014, 111:153-169.
[27]	EVGENIDIS S P, KARAPANTSIOS T D. Effect of bubble size on void fraction fluctuations in dispersed bubble flows[J]. Int. J. Multiph. Flow, 2015, 75:163-173.
[28]	XIA G D, LIU X F. An investigation of two-phase flow pressure drop in helical rectangular channel[J]. Int. Commun. Heat Mass, 2014, 54:33-41.
[29]	XIA G D, LIU X F, ZHAI Y L, et al. Single-phase and two phase flows through helical channels in single screw expander prototype[J]. J. Hydrodyn. Ser. B, 2014, 26:114-121.
[30]	LIU X F, XIA G D, YANG G. Experimental study on the characteristics of air-water two-phase flow in vertical helical rectangular channel[J]. Int. J. Multiph. Flow, 2015, 73:227-237.