Ratio analysis of two mechanisms of static droplet evaporation driven by pressure difference

  • Fulong Zhao
  • Qianfeng Liu
  • Lin Yu
  • Ruibo Lu
  • Hanliang Bo
  • Sichao TanEmail author
Research Article


When droplet moving in the steam-water separator, the gas pressure will decrease due to flow resistance and the liquid-vapor equilibrium at the droplet surface will be broken. The droplet evaporates continuously as a result. The fast evaporation mechanism and thermal balance evaporation mechanism are presented for the droplet evaporation at cases of pressure variation. The droplet phase change model due to pressure variation is formulated. Subsequently, the effects of pressure difference on the droplet evaporation characteristics are analyzed. The ratio analysis of the two mechanisms is conducted. The droplet evaporation map over the ratio of two mechanisms is drawn. The numerical results indicate that the pressure difference significantly influences the droplet evaporation characteristics. Under most conditions, the droplet evaporation characteristics are dominated by the combined action of two mechanisms. For large pressure difference and small droplets, the fast evaporation mechanism dominates the evaporation process, and vice versa. With increasing pressure difference between the droplet and the surrounding environment, the droplet evaporates faster and the percentage of fast evaporation mechanism decreases gradually. The present work can lay the foundation for further investigation on the moving droplet evaporation.


droplet evaporation map pressure difference ratio analysis fast evaporation mechanism thermal balance evaporation mechanism 



The authors are grateful for the support of this research by the National Key R&D Program of China (No. 2017YFE0106200), Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education (ARES-2018-02), and Science and Technology on Reactor System Design Technology Laboratory (HT-KFKT-09-2018004).


  1. Abramzon, B., Sirignano, W. A. 1989. Droplet vaporization model for spray combustion calculations. Int J Heat Mass Transfer, 32: 1605–1618.CrossRefGoogle Scholar
  2. Cai, B., Tuo, X. B., Song, Z. C., Zheng, Y. L., Gu, H. F., Wang, H. J. 2018. Modeling of spray flash evaporation based on droplet analysis. Appl Therm Eng, 130: 1044–1051.CrossRefGoogle Scholar
  3. Gao, W., Shi, Y., Han, X., Zhang, X., Cheng, Y. 2012. Droplet flash evaporation of mixed dehumidification solutions. CIESC Journal, 63: 3453–3459.Google Scholar
  4. Grant, G., Brenton, J., Drysdale, D. 2000. Fire suppression by water sprays. Prog Energ Combust, 26: 79–130.CrossRefGoogle Scholar
  5. Kataoka, H., Shinkai, Y., Hosokawa, S., Tomiyama, A. 2009. Swirling annular flow in a steam separator. J Eng Gas Turb Power, 131: 032904.CrossRefGoogle Scholar
  6. Kong, L. 2007. Engineering Fluid Mechanics. Beijing: China Electric Power Press.Google Scholar
  7. Kryukov, A. P., Levashov, V. Y., Sazhin, S. S. 2004. Evaporation of diesel fuel droplets: Kinetic versus hydrodynamic models. Int J Heat Mass Transfer, 47: 2541–2549.CrossRefGoogle Scholar
  8. Lewis, E. R. 2006. The effect of surface tension (Kelvin effect) on the equilibrium radius of a hygroscopic aqueous aerosol particle. J Aerosol Sci, 37: 1605–1617.CrossRefGoogle Scholar
  9. Liu, L., Bai, B. F. 2016. Scaling laws for gas-liquid flow in swirl vane separators. Nucl Eng Des, 298: 229–239.CrossRefGoogle Scholar
  10. Liu, L., Bi, Q. C., Li, H. X. 2009. Experimental investigation on flash evaporation of saltwater droplets released into vacuum. Microgravity Sci Tec, 21: 255–260.CrossRefGoogle Scholar
  11. Liu, L., Bi, Q. C., Liu, W. M., Qi, F. C., Bi, X. G. 2011. Experimental and theoretical investigation on rapid evaporation of ethanol droplets and kerosene droplets during depressurization. Microgravity Sci Tec, 23: 89–97.CrossRefGoogle Scholar
  12. Marek, R., Straub, J. 2001. Analysis of the evaporation coefficient and the condensation coefficient of water. Int J Heat Mass Transfer, 44: 39–53.CrossRefGoogle Scholar
  13. Nakao, T., Nagase, M., Aoyama, G., Murase, M. 1999. Development of simplified wave-type vane in BWR steam dryer and assessment of vane droplet removal characteristics. J Nucl Sci Technol, 36: 424–432.CrossRefGoogle Scholar
  14. Poling, B. E., Prausnitz, J. M., O’Connell, J. P. 2001. The Properties of Gases and Liquids, 5th edn. New York: Mcgraw-hill.Google Scholar
  15. Rahman, M. M., Tanaka, N., Yokobori, S., Hirai, S. 2013. Three dimensional numerical analysis of two phase flow separation using swirling fluidics. Energy and Power Engineering, 5: 301–306.CrossRefGoogle Scholar
  16. Satoh, I., Fushinobu, K., Hashimoto, Y. 2002. Freezing of a water droplet due to evaporation—heat transfer dominating the evaporation-freezing phenomena and the effect of boiling on freezing characteristics. Int J Refrig, 25: 226–234.CrossRefGoogle Scholar
  17. Wang, C., Xu, R. N., Song, Y., Jiang, P. X. 2017. Study on water droplet flash evaporation in vacuum spray cooling. Int J Heat Mass Transfer, 112: 279–288.CrossRefGoogle Scholar
  18. Xiong, Z. Q., Lu, M. C., Li, Y. Z., Gu, H. Y., Cheng, X. 2013. Effects of the slots on the performance of swirl-vane separator. Nucl Eng Des, 265: 13–18.CrossRefGoogle Scholar
  19. Xiong, Z. Q., Lu, M. C., Wang, M. L., Gu, H. Y., Cheng, X. 2014. Study on flow pattern and separation performance of air-water swirl-vane separator. Ann Nucl Energy, 63: 138–145.CrossRefGoogle Scholar
  20. Xu, W. W., Li, Q., Wang, J. J., Jin, Y. H. 2016. Performance evaluation of a new cyclone separator Part II simulation results. Sep Purif Technol, 160: 112–116.CrossRefGoogle Scholar
  21. Xu, X., Mao, J., Cao, R., Cheng, C. 1990. Combustion Theory and Combustion Equipment. Beijing: China Machine Press, 142–150.Google Scholar
  22. Yang, S., Tao, W. 2006. Heat Transfer, 4th edn. Beijing: Higher Education Press, 25–35.Google Scholar
  23. Zhang, H., Liu, Q. F., Qin, B. K., Bo, H. L. 2015. Modeling droplet-laden flows in moisture separators using k-d trees. Ann Nucl Energy, 75: 452–461.CrossRefGoogle Scholar
  24. Zhang, H., Liu, Q. F., Qin, B. K., Bo, H. L., Chen, F. 2016. Study on working mechanism of AP1000 moisture separator by numerical modeling. Ann Nucl Energy, 92: 345–354.CrossRefGoogle Scholar
  25. Zhang, T. 2011. Study on surface tension and evaporation rate of human saliva, saline, and water droplets. Master Dissertation. West Virginia University.Google Scholar
  26. Zhang, Y. S., Wang, J. S., Liu, J. P., Chong, D. T., Zhang, W., Yan, J. J. 2013. Experimental study on heat transfer characteristics of circulatory flash evaporation. Int J Heat Mass Transfer, 67: 836–842.CrossRefGoogle Scholar
  27. Zhao, F. L., Liu, Q. F., Bo, H. L. 2016a. Parameter analysis of the static droplets phase transformation under the pressure variation condition. In: Proceedings of the 24th International Conference on Nuclear Engineering, Volume 3: Thermal-Hydraulics, Paper No. ICONE24-60028.Google Scholar
  28. Zhao, F. L., Zhao, C. R., Bo, H. L. 2018. Droplet phase change model and its application in wave-type vanes of steam generator. Ann Nucl Energy, 111: 176–187.CrossRefGoogle Scholar
  29. Zhao, F., Bo, H., Liu, Q. 2016b. Static droplet phase transformation model for variable pressure conditions. Journal of Tsinghua University (Science and Technology), 56: 759–764, 771. (in Chinese)Google Scholar

Copyright information

© Tsinghua University Press 2019

Authors and Affiliations

  • Fulong Zhao
    • 1
  • Qianfeng Liu
    • 2
    • 3
  • Lin Yu
    • 1
  • Ruibo Lu
    • 1
  • Hanliang Bo
    • 2
  • Sichao Tan
    • 1
    Email author
  1. 1.Fundamental Science on Nuclear Safety and Simulation Technology LaboratoryHarbin Engineering UniversityHarbinChina
  2. 2.Institute of Nuclear and New Energy TechnologyTsinghua UniversityBeijingChina
  3. 3.Key Laboratory of Advanced Reactor Engineering and Safety, Ministry of EducationTsinghua UniversityBeijingChina

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