化工学报 ›› 2020, Vol. 71 ›› Issue (7): 3071-3079.doi: 10.11949/0438-1157.20191605

• 流体力学与传递现象 • 上一篇    下一篇

基于分子运动学的水汽在细颗粒表面异质核化的数值模拟

余廷芳1(),高巨1,熊桂龙2,3(),李水清3,姚强3   

  1. 1.南昌大学机电工程学院,江西 南昌 330031
    2.南昌大学资源环境与化工学院,江西 南昌 330031
    3.清华大学热科学与动力工程教育部重点实验室,北京 100084
  • 收稿日期:2020-01-02 修回日期:2020-04-09 出版日期:2020-07-05 发布日期:2020-07-09
  • 通讯作者: 熊桂龙 E-mail:yutingfang@ncu.edu.cn;jcijxcn@163.com
  • 作者简介:余廷芳(1974—),男,博士,教授,yutingfang@ncu.edu.cn
  • 基金资助:
    国家自然科学基金项目(51666011);江西省自然科学基金项目(20171ACB21008)

Numerical simulation of heterogeneous nucleation of water vapor on surface of fine particles based on molecular kinetics

Tingfang YU1(),Ju GAO1,Guilong XIONG2,3(),Shuiqing LI3,Qiang YAO3   

  1. 1.School of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, Jiangxi, China
    2.School of Resources Environmental and Chemical Engineering,Nanchang University, Nanchang 330031, Jiangxi, China
    3.Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Tsinghua University, Beijing 100084, China
  • Received:2020-01-02 Revised:2020-04-09 Online:2020-07-05 Published:2020-07-09
  • Contact: Guilong XIONG E-mail:yutingfang@ncu.edu.cn;jcijxcn@163.com

摘要:

为研究过饱和水汽在细颗粒表面异质核化特性,准确预测成核参数,基于分子运动学异质核化理论建立了过饱和水汽在燃煤细颗粒表面异质核化的运动学模型。数值分析了液滴晶核长大过程中水汽分子和水分子两种扩散凝结机制对晶核长大的促进作用及其相对重要性,数值预测了水汽过饱和度和宏观接触角对成核速率的影响;数值计算了不同温度和宏观接触角下细颗粒的临界过饱和度。结果表明:当液滴晶核尺寸小于临界晶核半径时,颗粒表面吸附水分子扩散凝结速率与水蒸气分子直接扩散凝结速率的比值大于100,颗粒表面吸附水分子的扩散凝结机制对晶核长大起主导作用。提高水汽过饱和度或减小宏观接触角均可显著提高液滴晶核的成核速率;成核速率随水汽过饱和度增大呈指数型增长。提高气相主体中水汽温度或减小细颗粒物的宏观接触角均可显著降低异质成核的临界过饱和度;对于粒径小于0.1 μm的细颗粒物,随着细颗粒粒径的增大,异质核化的临界过饱和度显著减小。

关键词: 细颗粒物, 水汽, 异质凝结, 核化, 数值模拟

Abstract:

To investigate the heterogeneous nucleation characteristics of supersaturated water vapor on the surface of fine particles, and accurately predict the nucleation parameters, a molecular kinetic model of heterogeneous nucleation of supersaturated water vapor on the surface of coal-fired fine particles was established based on the theory of molecular kinetic heterogeneous nucleation. The promotion effects and relative importance of two diffusion condensation mechanisms of water and vapor molecules to accelerate embryo growth and the influences of supersaturation and macroscopic contact angle on nucleation rate are systemically analyzed. Furthermore, the critical supersaturation for fine particles under different temperature and macroscopic contact angles are also predicted. The results show that when the radius of embryo is less than critical embryo radius, the ratio of diffusion condensation rate of water molecules absorbed on particle surface to direct vapor deposition condensation rate is always above 100, it indicates that the surface diffusion mechanism of absorbed water molecules plays a dominated role in embryo growth. The nucleation rate is remarkable increased with the increase of supersaturation or the decrease of macroscopic contact angle. Additionally, the nucleation rate increases exponentially with the increase of supersaturation. Increase the vapor temperature or decrease macroscopic contact angle can lead to a lower critical supersaturation. For fine particles with a particle size of less than 0.1 μm, as the fine particle size increases, the critical supersaturation of heterogeneous nucleation decreases significantly.

Key words: fine particles, water vapor, heterogeneous condensation, nucleation, numerical simulation

中图分类号: 

  • X 513

图1

凝结水分子和水汽分子横向、纵向扩散运动促进成核过程原理"

图2

水汽分子在细颗粒表面异相凝结分子运动学"

图3

模型预测结果与实验结果的比较"

图4

RTO随晶核液滴半径和粒径的变化"

图5

Lcvs/Scv随晶核液滴半径和粒径的变化"

图6

成核速率随过饱和度的变化"

图7

成核速率随粒径的变化"

图8

临界过饱和度随粒径和宏观接触角的变化"

图9

临界过饱和度随颗粒粒径和气相主体温度的变化"

1 Atkinson R W, Cohen A, Mehta S, et al. Systematic review and meta-analysis of epidemiological time-series studies on outdoor air pollution and health in Asia[J]. Air Quality, Atmosphere and Health, 2012, 5(4): 383-391.
2 Bentayeb M, Simoni M, Baiz N, et al. Adverse respiratory effects of outdoor air pollution in the elderly[J]. International Journal of Tuberculosis & Lung Disease: the Official Journal of the International Union Against Tuberculosis and Lung Disease, 2012, 16(9):1149-1161.
3 李晓航, 刘红刚, 路建洲, 等. 煤粉炉和循环流化床锅炉飞灰吸附汞动力学及其吸附机制[J]. 化工学报, 2019, 70(11): 4397-4409.
Li X H, Liu H G, Lu J Z, et al. Kinetics and mechanism of mercury adsorption on fly ashes from pulverized coal boiler and circulating fluidized bed boiler[J]. CIESC Journal, 2019, 70(11): 4397-4409.
4 周栋梁, 李水清, 靳星, 等. 电场、流场耦合作用下脱除细颗粒物的实验和数值模拟[J]. 中国电机工程学报, 2016, 36(2): 453-458.
Zhou D L, Li S Q, Jin X, et al. Experiments and numerical simulations of the removal of fine particles in the coupling field of electrostatic precipitators[J]. Proceedings of the CSEE, 2016, 36(2): 453-458.
5 Fan F X, Zhang S H, Peng Z B, et al. Numerical investigation of heterogeneous nucleation of water vapor on PM10 for particulate abatement[J]. The Canadian Journal of Chemical Engineering, 2019, 97: 930-939.
6 Heidenreich S, Ebert F. Condensational droplet growth as a preconditioning technique for the separation of submicron particles from gases[J]. Chemical Engineering & Processing, 1995, 34(3): 235-244.
7 Paiva J, Salcedo R, Araujo P. Impact of particle agglomeration in cyclones[J]. Chemical Engineering Journal, 2010, 162(3): 861-876.
8 熊桂龙, 李水清, 陈晟, 等. 增强 PM 2.5 脱除的新型电除尘技术的发展[J]. 中国电机工程学报, 2015, 35(9): 2217-2223.
Xiong G L, Li S Q, Chen S, et al. Development of advanced electrostatic precipitation technologies for reducing PM 2.5 emissions from coal-fired power plants[J]. Proceedings of the CSEE, 2015, 35(9): 2217-2223.
9 Bogodage S G, Leung A Y T. Improvements of the cyclone separator performance by down-comer tubes[J]. Journal of Hazardous Materials, 2016, 311: 100-114.
10 Yan J P, Chen L Q, Yang L J. Combined effect of acoustic agglomeration and vapor condensation on fine particles removal[J]. Chemical Engineering Journal, 2016, 290: 319-327.
11 Bin H, Yang Y, Cai L, et al. Experimental study on particles agglomeration by chemical and turbulent agglomeration before electrostatic precipitators[J]. Powder Technology, 2018, 335: 186-194.
12 Fan Y, Qin F H, Luo X S, et al. Heterogeneous condensation on insoluble spherical particles: modeling and parametric study[J]. Chemical Engineering Science, 2013, 102: 387-396.
13 孙宗康, 张笑丹, 杨林军, 等. 化学与湍流团聚耦合促进燃煤细颗粒物团聚与脱除[J]. 化工学报, 2020, 71(3): 1317-1325.
Sun Z K, Zhang X D, Yang L J, et al. Promoting the agglomeration and removal of coal-fired fine particles by coupling of chemical and turbulent agglomeration [J]. CIESC Journal, 2020, 71(3): 1317-1325.
14 周璐璐.燃煤细颗粒水汽相变长大特性实验研究[D].南京: 东南大学, 2015.
Zhou L L. Experimental research on the characteristics of growth by vapor condensation of coal ash particles[D]. Nanjing: Southeast University, 2015.
15 Tammaro M, Natale D F, Salluzzo A, et al. Heterogeneous condensation of submicron particles in a growth tube[J]. Chemical Engineering Science, 2012, 74(22): 124-134.
16 Xu J C, Yu Y Zhang J, et al. Heterogeneous condensation of water vapor on particles at high concentration[J]. Powder Technology, 2017, 305: 71-77.
17 Wu H, Pan D P, Huang R T, et al. Abatement of fine particle emission by heterogeneous vapor condensation during wet limestone-gypsum flue gas desulfurization[J]. Energy & Fuels, 2016, 30(7): 6103-6109.
18 李林, 凡凤仙. 可溶与不可溶混合PM2.5的蒸汽相变凝结增长[J]. 动力工程学报, 2015, 35(7): 581-587.
Li L, Fan F X. Growth of soluble and insoluble mixed PM2.5 by vapor heterogeneous condensation[J]. Journal of Chinese Society of Power Engineering, 2015, 35(7): 581-587.
19 Wu H, Pan D P, Xiong G L, et al. The abatement of fine particles from desulfurized flue gas by heterogeneous vapor condensation coupling two impinging steams [J]. Chemical Engineering and Processing, 2016, 108: 174-180.
20 温高森, 凡凤仙. 蒸汽凝结促进多分散不可熔PM2.5增长的数值模拟[J]. 高校化学工程学报, 2015, 29(3): 736-742.
Wen G S, Fan F X. Numerical analysis on growth of insoluble PM2.5 by vapor heterogeneous condensation[J]. Journal of Chemical Engineering of Chinese Universities, 2015, 29(3): 736-742.
21 Fletcher H N. Size effect in heterogeneous nucleation[J]. The Journal of Chemical Physics, 1958, 29: 572-576.
22 Padilla K, Talanquer V. Heterogeneous nucleation on aerosol particles[J]. Journal of Chemical Physics, 2001, 114(3): 1319-1325.
23 Lee Y H, Chou W S, Chen L H. The adsorption and nucleation of water vapor on an insoluble spherical solid particle[J]. Surface Science, 1998, 414: 363-373.
24 凡凤仙, 杨林军, 袁竹林, 等. 水汽在燃煤PM2.5表面异质核化特性数值预测[J].化工学报,2007,58(10): 2561-2566.
Fan F X, Yang L J, Yuan Z L, et al. Numerical prediction of water vapor nucleation behavior on PM2.5 from coal combustion[J]. Journal of Chemical Industry and Engineering (China), 2007, 58(10): 2561-2566.
25 Chen C C, Tao C J. Condensation of supersaturated water vapor on submicrometer particles of SiO2 and TiO2[J]. Journal of Chemical Physics, 2000, 112(22): 9967-9977.
26 Singha S K, Das P K, Maiti B. Inclusion of line tension effect in classical nucleation theory for the heterogeneous nucleation: a rigorous thermodynamic formulation and some unique conclusions[J]. The Journal of Chemical Physics, 2015, 142(10):104706.
27 Chen C C, Guo M S, Tsai Y J, et al. Heterogeneous nucleation of water vapor on submicrometer particles of SiC, SiO2 and naphthalene[J]. Journal of Colloid and Interface Science, 1998, 198(2): 354-367.
28 Hienola A I, Winkler P M, Wagner P E, et al. Estimation of line tension and contact angle from heterogeneous nucleation experimental data[J]. The Journal of Chemical Physics, 2007, 126(9): 094705.
29 Luo X S, Fan Y, Qin F H, et al. A kinetic model for heterogeneous condensation of vapor on an insoluble spherical particle[J]. The Journal of Chemical Physics, 2014, 140(2): 024708.
30 Fan Y, Qin F H, Luo X S, et al. A modified expression for the steady-state heterogeneous nucleation rate[J]. Journal of Aerosol Science, 2015, 87: 17-27.
31 徐俊超, 于燕, 张军, 等. 液滴在燃煤细颗粒表面凝结长大的运动学特性[J]. 东南大学学报(自然科学版), 2017, 47(3): 506-512.
Xu J C, Yu Y, Zhang J, et al. Kinetics study of droplet growth on surface of coal-fired fine particles[J]. Journal of Southeast University (Natural Science Edition), 2017, 47(3): 506-512.
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