蒸发热水塔内固体颗粒对气泡运动的影响
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摘要
以蒸发热水塔为研究对象进行可视化实验,借助高速摄像机以及图像处理软件研究热水塔内单孔筛孔塔板上方单个气泡的运动周期及运动特性,孔径为3 mm,在蒸汽中加入不凝性气体N2和N2/固体颗粒的混合物,研究固体颗粒对气泡生成、破碎与过程的影响。实验结果表明:气泡整个生长周期包括生成区、上升区、破碎区。气泡长径比在生成区由大变小,在上升区先增大后减小,在破碎区增大趋势明显;气泡的等效半径在整个运动周期中一直增大,其中在生成区的增大速度最快;生成区气泡的Y向运动速率呈现增大趋势,上升区以及破碎区气泡的上升速率平稳波动。当N2带入煤粉颗粒后,发现气泡的上升区时间比例大大降低,破碎区的占比增加明显,有利于塔内的热质传递。
The evaporative hot water tower was used as the research object for visualization experiments. The high-speed camera and image processing software were used to study the motion period and characteristics of a single bubble above the single-hole sieve tray in the hot water tower. The aperture was 3 mm. In the experiment process,non-condensable properties were added to the steam. A mixture of gaseous N2 and N2/solid particles was used to study the effect of solid particles on bubble formation, fragmentation and processes. The results show that the entire growth cycle of the bubble includes the formation zone, the rising zone and the crushing zone. The ratio of the bubble length to diameter decreases from large to small in the formation zone, increases first and then decreases inthe rising zone, and increases in the crushing zone. The equivalent radius of the bubble increases throughout theentire cycle of motion, with the highest growth rate in the formation zone. The Y-movement rate of bubbles in theformation zone shows an increasing trend, and the rising rate of bubbles in the rising zone and the crushing zone fluctuates smoothly. When N2 was introduced into the pulverized coal particles, it was found that the proportion of the rise time of the bubbles was greatly reduced, and the proportion of the crushing zone increased significantly,which was conducive to the transfer of heat within the tower.
The evaporative hot water tower was used as the research object for visualization experiments. The high-speed camera and image processing software were used to study the motion period and characteristics of a single bubble above the single-hole sieve tray in the hot water tower. The aperture was 3 mm. In the experiment process,non-condensable properties were added to the steam. A mixture of gaseous N2 and N2/solid particles was used to study the effect of solid particles on bubble formation, fragmentation and processes. The results show that the entire growth cycle of the bubble includes the formation zone, the rising zone and the crushing zone. The ratio of the bubble length to diameter decreases from large to small in the formation zone, increases first and then decreases inthe rising zone, and increases in the crushing zone. The equivalent radius of the bubble increases throughout theentire cycle of motion, with the highest growth rate in the formation zone. The Y-movement rate of bubbles in theformation zone shows an increasing trend, and the rising rate of bubbles in the rising zone and the crushing zone fluctuates smoothly. When N2 was introduced into the pulverized coal particles, it was found that the proportion of the rise time of the bubbles was greatly reduced, and the proportion of the crushing zone increased significantly,which was conducive to the transfer of heat within the tower.
引文
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[19] Cheng P, Wang G, Quan X. Recent work on boiling and condensation in microchannels[J]. Journal of Heat Transfer, 2009,131(4):569-574.
[20] Clerx N, van der Geld C W M. Experimental and analytical study of intermittency in direct contact condensation of steam in a crossflow of water[C]//Proceedings of ECI International Conference on Boiling Heat Transfer. Florianopolis, Brazil. 2009:1-8.
[21] Gulawani S S, Joshi J B, Shah M S, et al. CFD analysis of flow pattern and heat transfer in direct contact steam condensation[J].Chemical Engineering Science, 2006, 61(16):5204-5220.
[22] Pan L, Tan Z, Chen D, et al. Numerical investigation of vapor bubble condensation characteristics of subcooled flow boiling in vertical rectangular channel[J]. Nuclear Engineering and Design,2012, 248(1):126-136.
[23] Sachin K, Dahikar S K, Sathe M J, et al. Investigation of flow and temperature patterns in direct contact condensation using PIV,PLIF and CFD[J]. Chemical Engineering Science, 2010, 65(16):4606-4620.
[24] Jiang B, Liu P, Zhang L, et al. Hydrodynamics and mass-transfer analysis of a distillation ripple tray by computational fluid dynamics simulation[J]. Industrial&Engineering Chemistry Research, 2013, 52(49):17618-17626.
[25] Tian W, Ishiwatari Y, Ikejiri S, et al. Numerical simulation on direct contact condensation of single bubble in subcooled water using MPS method[C]//International Symposium on Multiphase Flow Heat Mass Transfer and Energy Conversion,2010, 1207(1):933-938.
[26] Zeng Q, Cai J. Three-dimension simulation of bubble behavior under nonlinear oscillation[J]. Annals of Nuclear Energy, 2014, 63(1):680-690.
[27] Chen Y M, Mayinger F. Measurement of heat transfer at the phase interface of condensing bubbles[J]. International Journal of Multiphase Flow, 1992, 18(6):877-890.
[28] Warrier G R, Basu N, Dhir V K. Interfacial heat transfer during subcooled flow boiling[J]. International Journal of Heat and Mass Transfer, 2002, 45(19):3947-3959.
[29] Pan L, Tan Z, Chen D, et al. Numerical investigation of vapor bubble condensation characteristics of subcooled flow boiling in vertical rectangular channel[J]. Nuclear Engineering and Design,2012, 248(1):126-136.
[30]马亮.浮选过程中含钙矿物颗粒与气泡的相互作用研究[D].长沙:中南大学, 2011.Ma L. Study on the interaction between calcium-containing mineral particles and bubbles during flotation[D]. Changsha:Central South University, 2011.
[2]于广锁,牛苗任,王亦飞,等.气流床煤气化的技术现状和发展趋势[J].现代化工, 2004, 24(5):23-26.Yu G S, Niu M R, Wang Y F, et al. Application status and development tendency of coal entrained-bed gasification[J].Modern Chemical Industry, 2004, 24(5):23-26.
[3]金建国,任吉堂,陈连生,等.引入固体颗粒强化膜态沸腾换热的机理分析[J].工程热物理学报, 2006, 27(5):820-822.Jing J G, Ren J T, Chen L S, et al. Mechanism analysis of enhanced boiling heat transfer by solid particles[J]. Journal of Engineering Thermophysics, 2006, 27(5):820-822.
[4]屈晓航,田茂诚,张冠敏,等.含不凝气体蒸汽泡直接接触冷凝[J].化工学报, 2014, 65(12):4749-4754.Qu X H, Tian M C, Zhang G M, et al. Direct contact condensation of steam bubbles with non-condensable gas[J]. CIESC Journal,2014, 65(12):4749-4754.
[5] Mochizuki T, Sato H, Mori Y H. Multi-angle observation scheme for bubbles and droplets[J]. Journal of Visualization, 2012, 15(2):125-137.
[6] Robin T T, Snyder N W. Theoretical analysis of bubble dynamics for an artificially produced vapor bubble in a turbulent stream[J].International Journal of Heat and Mass Transfer, 1970, 13(3):523-536.
[7]刘军云,王辉涛,王华,等.直接接触换热器中分散相单个气泡的传热机理研究[J].昆明理工大学学报(自然科学版), 2012,(2):55-59.Liu J Y, Wang H T, Wang H, et al. Heat transfer mechanism of a single dispersed phase of bubbles in direct contact heat transfer[J]. Journal of Kunming University of Science and Technology(Natural Science Edition), 2012,(2):55-59.
[8] Kamei S, Hirata M. Condensing phenomena of a single vapor bubble into subcooled water[J]. Experimental Heat Transfer,1987, 3(2):173-182.
[9] Harada T, Nagakura H, Okawa T. Dependence of bubble behavior in subcooled boiling on surface wettability[J]. Nuclear Engineering and Design, 2010, 240(12):3949-3955.
[10]马超,薄涵亮.单气泡破裂产生膜液滴空间分布实验研究[J].原子能科学技术, 2015, 49(10):1766-1771.Ma C, Bo H L. Experimental study on the spatial distribution of droplets produced by single bubble rupture[J]. Atomic Energy Science and Technology, 2015, 49(10):1766-1771.
[11] Hsieh C C, Wang S B, Pan C. Dynamic visualization of two-phase flow patterns in a natural circulation loop[J]. International Journal of Multiphase Flow, 1997, 23(6):1147-1169.
[12] Morita K, Matsumoto T, Fukuda K, et al. Experimental verification of the fast reactor safety analysis code SIMMER-Ⅲfor transient bubble behavior with condensation[J]. Nuclear Engineering and Design, 2008, 238(1):49-56.
[13] Suzuki T, Tobita Y, Yamano H, et al. Development of multicomponent vaporization/condensation model for a reactor safety analysis code SIMMER-Ⅲ:extended verification using multi-bubble condensation experiment[J]. Nuclear Engineering and Design, 2003, 220(3):240-254.
[14] Deandres M C, Hoo E, Zangrando F. Performance of directcontact heat and mass exchangers with steam-gas mixtures at subatmospheric pressures[J]. International Journal of Heat and Mass Transfer, 1996, 39(5):965-973.
[15]李少白.非牛顿流体中气泡运动及传质的研究[D].天津:天津大学, 2011.Li S B. Study on bubble motion and mass transfer in nonNewtonian fluids[D]. Tianjin:Tianjin University, 2011.
[16] Genid S B. Direct-contact condensation heat transfer on downcommerless trays for steam-water system[J]. International Journal of Heat and Mass Transfer, 2006, 49(7):1225-1230.
[17] Genid S B, Jadimovic B M, Vladic L A. Heat transfer rate of direct-contact condensation on baffle trays[J]. International Journal of Heat and Mass Transfer, 2008, 51(25/26):5772-5776.
[18]袁惠新,鲁娣,等.气泡与颗粒在流场中的碰撞聚集和破碎[J].过滤与分离, 2008, 3(4):12-15.Yuan H X, Lu D, et al. Collision and aggregation of air bubbles and particles in the flow field[J]. Journal of Filtration&Separation, 2008, 3(4):12-15.
[19] Cheng P, Wang G, Quan X. Recent work on boiling and condensation in microchannels[J]. Journal of Heat Transfer, 2009,131(4):569-574.
[20] Clerx N, van der Geld C W M. Experimental and analytical study of intermittency in direct contact condensation of steam in a crossflow of water[C]//Proceedings of ECI International Conference on Boiling Heat Transfer. Florianopolis, Brazil. 2009:1-8.
[21] Gulawani S S, Joshi J B, Shah M S, et al. CFD analysis of flow pattern and heat transfer in direct contact steam condensation[J].Chemical Engineering Science, 2006, 61(16):5204-5220.
[22] Pan L, Tan Z, Chen D, et al. Numerical investigation of vapor bubble condensation characteristics of subcooled flow boiling in vertical rectangular channel[J]. Nuclear Engineering and Design,2012, 248(1):126-136.
[23] Sachin K, Dahikar S K, Sathe M J, et al. Investigation of flow and temperature patterns in direct contact condensation using PIV,PLIF and CFD[J]. Chemical Engineering Science, 2010, 65(16):4606-4620.
[24] Jiang B, Liu P, Zhang L, et al. Hydrodynamics and mass-transfer analysis of a distillation ripple tray by computational fluid dynamics simulation[J]. Industrial&Engineering Chemistry Research, 2013, 52(49):17618-17626.
[25] Tian W, Ishiwatari Y, Ikejiri S, et al. Numerical simulation on direct contact condensation of single bubble in subcooled water using MPS method[C]//International Symposium on Multiphase Flow Heat Mass Transfer and Energy Conversion,2010, 1207(1):933-938.
[26] Zeng Q, Cai J. Three-dimension simulation of bubble behavior under nonlinear oscillation[J]. Annals of Nuclear Energy, 2014, 63(1):680-690.
[27] Chen Y M, Mayinger F. Measurement of heat transfer at the phase interface of condensing bubbles[J]. International Journal of Multiphase Flow, 1992, 18(6):877-890.
[28] Warrier G R, Basu N, Dhir V K. Interfacial heat transfer during subcooled flow boiling[J]. International Journal of Heat and Mass Transfer, 2002, 45(19):3947-3959.
[29] Pan L, Tan Z, Chen D, et al. Numerical investigation of vapor bubble condensation characteristics of subcooled flow boiling in vertical rectangular channel[J]. Nuclear Engineering and Design,2012, 248(1):126-136.
[30]马亮.浮选过程中含钙矿物颗粒与气泡的相互作用研究[D].长沙:中南大学, 2011.Ma L. Study on the interaction between calcium-containing mineral particles and bubbles during flotation[D]. Changsha:Central South University, 2011.