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.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Abramzon, B., Sirignano, W. A. 1989. Droplet vaporization model for spray combustion calculations. Int J Heat Mass Transfer, 32: 1605–1618.
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.
Gao, W., Shi, Y., Han, X., Zhang, X., Cheng, Y. 2012. Droplet flash evaporation of mixed dehumidification solutions. CIESC Journal, 63: 3453–3459.
Grant, G., Brenton, J., Drysdale, D. 2000. Fire suppression by water sprays. Prog Energ Combust, 26: 79–130.
Kataoka, H., Shinkai, Y., Hosokawa, S., Tomiyama, A. 2009. Swirling annular flow in a steam separator. J Eng Gas Turb Power, 131: 032904.
Kong, L. 2007. Engineering Fluid Mechanics. Beijing: China Electric Power Press.
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.
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.
Liu, L., Bai, B. F. 2016. Scaling laws for gas-liquid flow in swirl vane separators. Nucl Eng Des, 298: 229–239.
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.
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.
Marek, R., Straub, J. 2001. Analysis of the evaporation coefficient and the condensation coefficient of water. Int J Heat Mass Transfer, 44: 39–53.
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.
Poling, B. E., Prausnitz, J. M., O’Connell, J. P. 2001. The Properties of Gases and Liquids, 5th edn. New York: Mcgraw-hill.
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.
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.
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.
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.
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.
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.
Xu, X., Mao, J., Cao, R., Cheng, C. 1990. Combustion Theory and Combustion Equipment. Beijing: China Machine Press, 142–150.
Yang, S., Tao, W. 2006. Heat Transfer, 4th edn. Beijing: Higher Education Press, 25–35.
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.
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.
Zhang, T. 2011. Study on surface tension and evaporation rate of human saliva, saline, and water droplets. Master Dissertation. West Virginia University.
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.
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.
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.
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)
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).
About this article
Cite this article
Zhao, F., Liu, Q., Yu, L. et al. Ratio analysis of two mechanisms of static droplet evaporation driven by pressure difference. Exp. Comput. Multiph. Flow 1, 116–129 (2019). https://doi.org/10.1007/s42757-019-0011-4
- droplet evaporation map
- pressure difference
- ratio analysis
- fast evaporation mechanism
- thermal balance evaporation mechanism