The assessment of extinction mechanisms involving water mist applied to combustible liquids

Introduction. A number of problems accompany the development of new extinction methods applicable on the premises of buildings and structures and the use of advanced fire extinguishing agents. Subject-specific studies are needed to solve these problems. They include the identification of general principles of fire extinguishing efficiency and further development of the optimal mode of application of firefighting agents. The purpose of this work is the theoretical assessment of fire extinction mechanisms involving the water mist applied to combustible liquids. The objectives to be accomplished include the equations based on the mass/energy conservation laws and derived for flame zones with account taken of the water mist applied; the assessment of the water flow rate for different combustion mechanisms; comparison of assessment results with experimental data obtained in the process of extinguishing model fire seats that have burning combustible fluids.

Methods of analysis. The calculations involve the equations based on the mass/energy conservation laws and derived for flame zones above the surface of combustibles.

Research results. The author analyzes two fire extinguishing mechanisms that contribute to the suppression of burning in the flame zone: 1) the attainment of the value of mass concentration of water vapour that reaches the lower concentration limit of combustion of the combustible mixed gas (oxygen reduction); 2) cooling combustible mixed gas in the flame zone by evaporating water until the flash point temperature of combustible vapour is reached.

Conclusions: Equations based on mass/energy conservation laws were derived for flame zones, formed in the course of combustion of flammable liquids, with account taken of a jet of water mist. Water flow rates needed for the implementation of various extinguishing mechanisms were analyzed using the proposed equations. Theoretical results were compared with the experimental data obtained in the process of using water mist to extinguish model fire seats that contain combustible fluids.

1. Aleshkov M.V., Gusev I.A. Ensuring technology of fire extinguishing in the closed power engineering facilities. Security Systems : Materials of the 26th International Scientific and Practical Conference. Moscow, Academy of State Fire Service of Emercom of Russia, 2017; 176-179. URL: https://www.elibrary.ru/item.asp?id=32292947 (rus).

2. Kopylov N.P., Khasanov I.R., Kuznetsov A.E., Fedotkin D.V., Moskvilin E.A., Strizhak P.A., Karpov V.N. Parameters of water dumping by airplanes during forest fire suppression. Fire Safety. 2015; 2:49-55. (rus).

3. Gergel V.I., Meshalkin E.A. Fire extinguishing by finely-dispersed water of high pressure. Pozharovzryvobezopasnost/Fire and Explosion Safety. 2017; 26(3):45-49. DOI: 10.18322/PVB.2017.26.03.45-49 (rus).

4. Kozhinov S. Extinguishing electrical equipment under voltage with water mist. Safety. Credibility. Information. 2008; 79:46-47. (rus).

5. Gergel V.I., Meshalkin E.A. Fire extinguishing with water mist. Materials of the XXIX International Scientific and Practical Conference dedicated to the 80th anniversary of the Federal State-Financed Establishment All-Russian Research Institute for Fire Protection of Ministry of Russian Federation for Civil Defense, Emergencies and Elimination of Consequences of Natural Disasters. Part 2. Combustion and problems of extinguishing fires. Moscow, VNIIPO Publ., 2017; 369-372. URL: https://www.elibrary.ru/item.asp?id=29942838 (rus).

6. Meshman L.M. Special issues on design water AFEI. Pozharovzryvobezopasnost/Fire and Explosion Safety. 2019; 28(1):80-88. URL: https://www.fire-smi.ru/jour/article/view/741 (rus.)

7. Voytkov I.S., Volkov R.S., Vysokomornaya O.V., Chernova G.A., Fadeev A.V. Experimental study of temperature traces of water droplets, water flow masses and aerosol flows moving through high-temperature combustion products. Pozharovzryvobezopasnost/Fire and Explosion Safety. 2016; 25(8):17-26. DOI: 10.18322/PVB.2016.25.08.17-26 (rus).

8. Volkov R.S., Kuznetsov G.V., Legros J.C., Strizhak P.A. Experimental investigation of consecutive water droplets falling down through high-temperature gas zone. International Journal of Heat and Mass Transfer. 2016; 95:184-197. DOI: 10.1016/j.ijheatmasstransfer.2015.12.001

9. Zhang Qinglin, Wang Lu, Bi Yixing, Xu Dajun, Zhi Huiqiang, Qiu Peifang. Experimental investigation of foam spread and extinguishment of the large-scale methanol pool fire. Journal of Hazardous Materials. 2015; 287:87-92. DOI: 10.1016/j.jhazmat.2015.01.017

10. Blinov V.I., Khudyakov G.N. Diffusion burning of liquids. Moscow, Russian Academy of Sciences Publ., 1961; 208. (rus).

11. Sharovarnikov S.A., Korolchenko D.A. Extinguishing of combustible liquid by atomized water. Pozharovzryvobezopasnost/Fire and Explosion Safety. 2013; 22(11):70-74. URL: https://www.elibrary.ru/item.asp?id=20655296 (rus).

12. Korolchenko D.A., Degaev E.N., Sharovarnikov A.F. Combustion of heptane in a model tank. Pozharovzryvobezopasnost/Fire and Explosion Safety. 2015; 24(2):67-70. URL: https://www.firesmi.ru/jour/article/view/363 (rus).

13. Snegirev A.Yu., Sazhin S.S., Talalov V.A., Snegirev A.Yu., Sazhin S.S., Talalov V.A. Model and algorithm of estimate of heat transfer and evaporation of dispersed liquid’s drops. St. Petersburg State Polytechnical University Journal. Physics and Mathematics, 2011; 1:44-55. URL: https://cyberleninka.ru/article/n/model-i-algoritm-rascheta-teploobmena-i-ispareniya-kapel-dispergirovannoy-zhidkosti (rus).

14. Korolchenko D.A., Gromovoy V.U., Vorogushin O.O. Fire extinguishing in tall buildings by using water mist systems. Vestnik MGSU. 2011; 1-2:331-335. (rus).

15. Puzach S.V. Methods for calculating heat and mass transfer during a fire at the premises and their application in solving practical fire and explosion safety problems. Moscow, Academy of State Fire Service of Emercom of Russia Publ., 2005; 336. (rus).

16. NFPA 92B. 1990 NFPA Technical Committee Reports –– Technical Guide for Smoke Management Systems in Malls, Atria and Large Areas. Quincy, MA, National Fire Protection Association, 1990.

17. Emeljanov A.L., Platunov E.S. Vaporization kinetics of drops in cooling system of instrument component under high density of heat flow. Journal of Instrument Engineering. 2011; 54(1):84-88. URL: http://pribor.ifmo.ru/ru/article/5552/kinetika_ispareniya_kapelv_sistemah_ohlazhdeniyateplonagruzhennyh_elementov_priborov.htm (rus).

18. Yoshida A., Kashiwa K., Hashizume S., Naito H. Inhibition of counterflow methane/air diffusion flame by water mist with varying mist diameter. Fire Safety Journal. 2015; 71:217-225. DOI: 10.1016/j.firesaf.2014.11.030

19. Laufer J. The structure of turbulence in fully developed pipe flow. NACA Report 1174. 1954; 417-434. URL: http://naca.central.cranfield.ac.uk/reports/1954/naca-report-1174.pdf

20. Guildenbecher D.R., Sojka P.E. Experimental investigation of aerodynamic fragmentation of liquid drops modified by electrostatic surface charge. Atomization and Sprays. 2011; 21(2):139-147. DOI: 10.1615/AtomizSpr.2011003299

21. Kennedy M.J., Conroy M.W., Dougherty J.A., Otto N., Williams B.A., Ananth R., Fleming J.W. Bubble coarsening dynamics in fluorinated and non-fluorinated firefighting foams. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2015; 470: 268-279. DOI: 10.1016/j.colsurfa.2015.01.062

22. Korolchenko D.A., Sharovarnikov A.F. Universality of mechanisms of fire suppression by various extinguishing agents. Pozharovzryvobezopasnost/Fire and Explosion Safety. 2014; 23(11):84-88. URL: https://cyberleninka.ru/article/n/universalnost-mehanizmov-tusheniya-plameni-razlichnymiognetushaschimi-veschestvami (rus).

23. Korolchenko D.A., Sharovarnikov A.F. Analysis of the dual fire suppression mechanism. Pozharovzryvobezopasnost/Fire and Explosion Safety. 2014; 23(12):59-68. URL: https://cyberleninka.ru/article/n/analiz-dvoystvennogo-mehanizma-tusheniya-plameni (rus).