Fire suppression by low-volatile chemically active fire suppressants using aerosol technology

The motion of a manifold of liquid droplets in the counterflow of high-temperature (above 1000 K) gases has been experimentally studied for variable initial size (0.01–0.05 mm) and velocity (0.1–0.5 m/s) of droplets and the gas flow velocity (0.1–2 m/s). The properties of gas-vapor-droplet mixtures were monitored by optical diagnostic techniques. Conditions under which the trajectories and velocities of droplets moving in a high-temperature gas counterflow exhibit significant changes are determined.

The motion of a manifold of finely dispersed liquid droplets in the counterflow of high-temperature gases

Results of laboratory experiments were verified by full-scale tests in which two types of model fire sources were extinguished by salt-solution aerosols. The tests showed that short-term action of an aerosol cloud of an aqueous solution of potassium ferricyanide K3[Fe(CN)6] on the flame front of a surface forest fire led to suppression of the gas-phase combustion, and in the case of a model fire source of class A (burning wood) to its complete extinction. The minimum extinguishing mass concentration of K3[Fe(CN)6] in these experiments — 4.5 g/m3 — is close to that measured earlier in laboratory experiments. It was found that, in fire suppression by an aerosol of the aqueous solution of K3[Fe(CN)6], the volumetric flow rate of this fire suppressant was 30 times lower than the standard flow rate of pure water from a fire hose.

Fire suppression by aerosols of aqueous solutions of salts

Consequences of collisions between two water droplets upon their motion in high-temperature (about 1100 K) gases are analyzed statistically. The initial radii and motion velocities of the droplets varied within 0.1–0.25 mm and 0.5–5 m/s, respectively. The velocity of the counterflowing gas was 1.5 m/s. Using panoramic methods and tools of high-speed and cross-correlation video recording, conditions corresponding to different consequences (coagulation, decomposition, or breakup) of collisions between droplets are determined.

Statistical analysis of consequences of collisions between two water droplets upon their motion in a high-temperature gas flow

In this paper, we present the results of experimental studies of vaporization and fragmentation of droplets of fire-extinguishing compounds using suspensions and emulsions as examples. It was shown (using rapeseed oil as an example) that, when a combustible liquid of plant origin is added to their composition, micro-explosion or puffing, which are modes of secondary atomization of droplets, can take place. The ranges of changes in the lifetimes of droplets at different heating temperatures and component concentrations are established.

https://link.springer.com/content/pdf/10.1134/S1063785020020029.pdf

Intensification of Vaporization and Secondary Atomization of Droplets of Fire-Extinguishing Liquid Composition

The electric explosion of a wire in a thin-walled cylindrical glass ampule filled with water results in the formation of a disperse water (DW) cloud having a ring shape, which expands rapidly in the radial direction and slowly in the axial direction. Interaction of the DW with a flame produces fire quenching in the interaction zone. Experimental results are used for estimating the requirements and consumptions for creating DW clouds capable of quenching large-scale fires.

Interaction of dispersed water with flame

This paper describes a laboratory method for studying flame suppression by a dispersed water cloud produced by an electrically exploded wire in a thin-wall cylindrical glass capsule filled with water. Experimental results are simulated numerically.

V. I. Dudin

Papers

Interaction of dispersed water with flame

Method for Studying the Interaction of Dispersed Water with Flame