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Research of the extinguishing properties of water and hydrogel with carbon nanoparticles for liquidation burning of the petroleum products

Journal: Pozharovzryvobezopastnost/Fire and Explosion Safety (Vol.26, No. 8)

Publication Date:

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Page : 31-44

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Abstract

The use of sprayed water to extinguish fires in petroleum products is limited by the relatively low rate of vaporization due to the large average size of the droplets of the extinguishing agent. As methods to increase the efficiency of water-based fire, an electrophysical method for controlling the properties of substances at the interface is used, as well as a reagent modification - the deposition of nanomaterial with multilayered carbon nanotubes (MWCNT) into the liquid, and the use of gelling agents to stabilize the nanofluid. Raman spectroscopy revealed the presence in the nanomaterial, in addition to MWCNT, of a large number of by-products of nanotube synthesis. In the electrophysical action, characteristic peaks of nanostructures in water and hydrogel are observed, due to the predominant grouping of MWCNT in the near-surface layer of the liquid. With the help of atomic force microscopy, extended carbon nanostructures included in the composition of the extinguishing agent, as well as traces of amorphous carbon, were observed. In the course of the study, it was found that the increase in the rate of heating of the nanofluid is directly dependent on the concentration of the MWCNT nanomaterial and increases in comparison with distilled water (by 70 % - for the concentration of nanoparticles in water by 1.6 % by vol. and by 50 % - for the concentration of nanoparticles in the hydrogel 1.0 % by vol.), which can be explained by an increase in the thermal conductivity of the system due to a larger number of carbon nanotubes that are conductors of heat from the source of heating. The results obtained allow to select from the presented liquids containing the nanomaterial at a concentration of 1.0 % by vol. as the most effective for cooling the combustion of petroleum products of the combustion zone and to ensure its stability. When determining the surface tension coefficient of a nanofluid, water surface with a nanomaterial (DW + MWCNT 1.0 % by vol.) has a surface tension reduction of 20 %, for hydrogels (DW + Carbopol 0.2 % by mass) - by 58 %. When impact occurs electrophysical additional reduction of surface tension by 10 % preferably for all samples. A significant decrease in the value of the surface tension of the nanofluid, due to the introduction of MWCNT and the gelling component, leads to a decrease in the droplet size by more than 20 % in comparison with the base liquid while maintaining the parameters of the spraying of the extinguishing agent. This helps to reduce the size of droplets in the fire extinguishing substance in the near-surface layer of the burning liquid, increases the efficiency of the process of extinguishing the flame of petroleum products. During the experiments, it was found that the quenching time of water-based nanofluids with MWCNT nanomaterial 1.0 % by vol. on average 5.5 times less than the time of quenching the liquid with water. For hydrogels (DW + Carbopol 0.2 % by mass) with nanomaterial MWCNT 1 % by vol. the fire-fighting time was reduced to 10 times. The intensity of extinguishing water with nanomaterial MWCNT 1 % by vol. decreased by 2 times, and for hydrogels (DW + Carbopol 0.2 % by mass) with nanomaterial MWCNT 1 % by vol. - 3 times. In electrophysical conditions of exposure to the test is an additional nanofluids (10-15 %) reduction of the quenching time and the flow rate of the extinguishing agent. Summarizing the obtained results, it can be concluded that the increase in the fire-extinguishing efficiency of modified extinguishing agents based on atomized water is achieved due to the high thermal stability of the nanomaterial, improved thermal diffusivity of the nanoparticle with MWCNT, stabilization of nanoparticles in the liquid and reducing the rate of their agglomeration, reducing the droplet size by reducing the surface tension and increasing the fluid density.

Last modified: 2018-10-17 22:56:28