The Influence of K4[Fe(CN)6] Aerosol on the Flame Speed of Methane-air Flame

AbstractThe influence of 1% aerosol of the water solution of potassium ferrocyanide K4[Fe(CN)6] on the flame speed of stoichoimetric methane- air flame, stabilized over the Mache-Hebra burner, has been studied experimentally and by computer simulation. The flame speed was measured at atmospheric pressure and the temperature 93°C. Addition of the aerosol of the water solution of potassium ferrocyanide results in significantly greater reduction of the flame speed of stoichiometric methane-air flame, compared to aerosol addition without the salt. Modeling the flame speed with the mechanism GRI-Mech 3.0 shows this effect to be caused by the presence of potassium atoms in the composition of this salt. The results obtained account for effectiveness of applying fine aerosol of the water solution of K4[Fe(CN)6] in extinguishing fires

Combustion Chemistry and Decomposition Kinetics of Forest Fuels

AbstractA brief review is given of the studies in combustion chemistry and decomposition kinetics of forest fuels (FF). The methods used in the study to investigate the FF pyrolysis kinetics and the combustion of the Siberian forests are described. The experiments on FF pyrolysis were conducted at high heating rates (150K/s) in a flow reactor by the method of differential mass-spectrometric thermal analysis (DMSTA) in situ using probe molecular-beam mass spectrometry, and at low heating rates (0.17K/s) by the thermogravimetric method. The kinetic parameters of Siberian FF pyrolysis have been determined for oxidative and inert media and simulation of FF pyrolysis has been conducted using the multi-component devolatilization mechanism. The flame structure of a pine branch has been studied by probe molecular-beam mass spectrometry. Species have been identified in the dark and luminous flame zones; the width of the flame zone has been measured

Study of the Efficiency of Two Antipyrenes for the Creation of Fireproof Polymeric Composite Materials

Most of polymeric materials, when exposed to high temperatures, heat flows or an open flame, are capable of exothermic oxidation reactions – combustion. That is why polymeric materials are fire hazardous. The studies on creating a non-flammable polymer materials are crucial, as such products can make our everyday life a lot more safe. Studies have been carried out to assess the effectiveness of the action of two types of fire retardants (graphene and an organic phosphorus-containing compound DOPO-THPO), introduced into an epoxy resin. Evaluation of the effectiveness of the fire-retardant action was carried out by the methods of oxygen index (OI) and flammability according to UL 94. For the investigated compositions, it was found that there is no direct correlation between the value of the oxygen index and the ability of the samples to maintain self-combustion. For these compositions, the total duration of residual combustion in vertical tests and the speed of flame propagation in horizontal tests are naturally correlated. It was found that if the total duration of combustion of five samples during vertical tests is 500 seconds or less, then these compositions during horizontal tests will fade, that is, formally, their flame propagation speed will be equal to zero

Fuel-Rich Premixed n-Heptane/Toluene Flame: A Molecular Beam Mass Spectrometry and Chemical Kinetic Study

The mole fraction profiles of major flame species and intermediates including PAH precursors are measured in an atmospheric premixed burner-stabilized fuel-rich (φ = 1.75) n-heptane/toluene/O2/Ar flame (n-heptane/toluene ratio is 7:3 by liquid volume). These data are simulated with a detailed, extensively validated chemical kinetic reaction mechanism for combustion of n-heptane/toluene mixture, involving the reactions of PAH formation. The mechanism is extended with cross reactions for n-heptane and toluene derivatives. A satisfactory agreement between the new experimental data on the structure of n-heptane/toluene flame and the numerical simulations is observed. The mechanism reported can be successfully used in the models of practical fuel surrogates for reproducing the formation of soot precursors. The analysis of the reaction pathways shows that in the flame of the n-heptane/toluene blend (7:3 liquid volume ratio) the reactions dominant for the formation of the first aromatic ring (benzene and phenyl) are as those typical for pure toluene flames. The discrepancies between the measured and calculated species mole fractions are detected as well. The steps for the mechanism improvements are determined on the basis of the sensitivity analysis performed. To our knowledge, the measurements of mole fraction profiles of PAH and intermediates reported here, are the first of its kind and represent an unique data set extremely important for validation of chemical kinetic mechanisms for combustion of practical fuels

The effect of methyl pentanoate addition on the structure of a non-premixed counterflow n‑heptane/O2 flame

The influence of methyl pentanoate (MP) addition to n-heptane on the species pool in a nonpremixed counterflow flame fueled with n-heptane at atmospheric pressure has been investigated experimentally and numerically. Two non-premixed flames in counterflow configuration have been examined: (1) n-heptane/Ar (5.3%/94.7%) vs O2/Ar (24.1%/75.9%) and (2) n-heptane/MP/Ar (2.5%/2.5%/95%) vs O2/Ar (19.6%/80.4%). Both flames had similar strain rates and stoichiometric mixture fractions to allow an adequate comparison of their structures. The mole fraction profiles of the reactants, major products, and intermediates in both flames were measured using flame sampling molecular beam mass spectrometry. These experimental data were used for validation of a detailed chemical kinetic mechanism, which was proposed earlier for prediction of combustion characteristics of n-heptane/iso-octane/toluene/MP mixtures. The addition of MP to n-heptane reduced the flame temperature and the peak mole fractions of many flame intermediates, responsible for the formation of polycyclic aromatic hydrocarbons, specifically, of benzene, cyclopentadienyl, acetylene, propargyl, and vinylacetylene. Significant discrepancies between the calculated and measured mole fractions of cyclopentadienyl and benzene were found. A kinetic analysis of the reaction pathways resulting in formation of these intermediates in both flames and a sensitivity analysis of cyclopentadienyl and benzene were carried out to understand the origins of the observed discrepancies. The peak mole fractions of the major flame radicals (H, O, OH, CH3) were found to decrease with MP addition. The influence of MP addition on the relative contributions of the primary stages of n-heptane consumption is discussed

Influence of Triphenyl Phosphate on Degradation Kinetics of Ultrahigh-molecular-weight Polyethylene in Inert and Oxidative Media

AbstractThe kinetics and the mechanism of thermal decomposition of ultrahigh-molecular-weight polyethylene without additive and with TPP additives in oxidative and inert media has been studied using the method of differential mass-spectrometric thermal analysis at a high heating rate and the method of thermogravimetric analysis at a low heating rate, aimed at understanding the mechanism of reducing combustibility of UHMWPE with TPP additives. The results of the study may testify to the fact that not the thermal polymer degradation reactions but the gas-phase reactions in the UHMWPE flame with TPP participation are responsible for flame retardancy of UHMWPE