Numerical and Experimental Research of Heat and Mass Transfer at the Heterogeneous System Ignition by Local Energy Source with Limited Heat Content

Abstract

Numerical and experimental investigations were executed for determination of macroscopic regularities of heat and mass transfer processes under the conditions of the phase transformations and chemical reaction at the ignition of vapors coming from fabrics impregnated by combustible liquid into oxidant area at the local power supply. It was established that initial temperatureΘp>1of local energy source and volume fractionφ>30%of combustible liquid vapors in fabric are necessary for realization of ignition conditions in a system “fabric—combustible liquid—oxidant.”. Thus three ignition modes are possible for such system. The most widespread mode is an arrangement of ignition zone near the lateral side of local energy source. Also we obtained approximating expressions of ignition delay time on initial temperature and characteristic size of a local energy source for fabrics impregnated by some kinds of combustible liquids (gasoline, kerosene, and diesel fuel). Its dependences may be useful at engineering calculations of fire danger for processes of single hot particles interaction with liquid combustible substances.

Water droplet deformation in gas stream: Impact of temperature difference between liquid and gas

“…The obtained results are important to improve the present understanding of liquid droplet motions through gas streams and can be used to improve and to develop technologies such as cooling towers and high-temperature water purification, and also the important needs to improve the polydisperse vapor-water fire extinguishing technologies [43][44][45][46][47][48] because of the extremely important financial consequences of these natural and technogenical issues caused by uncontrollable natural phenomena as well as to the use of bigger and bigger amount of highly flammable substances [49][50][51][52].…”

A Hot Spots Ignition Probability Model for Low-Velocity Impacted Explosive Particles Based on the Particle Size and Distribution

“…Jankowski's model investigated the heterogeneous mixture combustion of liquid fuels and researched processes of spraying and combustion [16]. Numerical and experimental investigations were executed for determination of macroscopic regularities of heat and mass transfer processes under the conditions of the phase transformations and chemical reactions [17]. The physical and forecasting mathematical models about heat and mass transfer with phase transformations and chemical reactions under heating and following ignition of typical liquid fuel were developed [18].…”

“…Firstly, supposing that the samples are composed of the mean size particles, we use (1)-(3), (7)-(10), (14), and (18) to get ℎ, , , , V , and load . We assume that the force exerted on the each particles is equal; then we use (2)-(6) and (9)- (17) During the impact process, the contact areas between particles and between the particles and the surface will form potential "hot spots" due to plastic work and frictional heat. We suppose that potential hot spots are independent and small compared with the impacting drop weight surface.…”

Experimental Analysis of the Feasibility of Polydisperse Droplet Water Flow Using at Fire Extinguishing

“…Currently water mist sprayers are actively produced. Results of researches [3][4][5] which show that the sprayed phlegmatizators of burning can localize rather effectively a flame (and to liquidate the ignition center as a whole) are published. Thus, one of the main tasks which faces to the scientists by the development of such technology is the achievement of conditions of full extinguishing liquid evaporation in a flame zone.…”