Diffusion flame

About: Diffusion flame is a research topic. Over the lifetime, 9266 publications have been published within this topic receiving 233522 citations.

Experimental study of the inhibition of premixed and diffusion flames by iron pentacarbonyl

Abstract: The recent ban on the production of CF3Br has motivated a search for alternate agents for fire suppression: however, a replacement agent with all of the desirable properties of CF3Br is proving difficult to find. While most of the research has concentrated on other halogenated agents, there exist agents that are much more effective than CF3Br but about whose inhibition mechanism less is known. These agents typically involve a condensed phase. This paper investigates the behavior of iron pentacarbonyl(Fe(CO)5), one of the most efficient inhibitors identified in the past, in methane/oxygen/nitrogen flames: measurments are reported for both diffusion and premixed flames. The reduction in the extinction strain rate and laminar burning velocity with addition of iron pentacarbonyl is determined over moderate ranges of fuel-air equivalence ratio and oxygen mole fraction XO2. The flame and inhibitor locations in the counterflow diffusion flame experiments are varied to control the condensed- and gas-phase species transport rates to the flames and the chemical environment for their reaction. In the premixed flames, iron pentacarbonyl at low concentration reduces the burning velocity up to 100 times more effectively than CF3Br and shows a strong dependence on both and Xo2; however, at Fe(CO)5 mole fractions above a few hundred ppm, there is no additional reduction of the burning velocity. In diffusion flames, Fe(CO)5 is again shown to be more effective at the lowest concentrations, but the inhibition effect does not level off at higher mole fractions as it does in the premixed flames. In addition, combinations of flame and inhibitor location in the counterflow flames have been found for which iron pentacarbonyl either provides negligible inhibition at any mole fraction or promotes the combustion. The possible mechanisms are discussed.

Influence of Sampling and Storage Protocol on Fractal Morphology of Soot Studied by Transmission Electron Microscopy

Abstract: The aim of this work was to compare the fractal characteristics, Df and kf, the primary particle diameter, Dpp, the gyration diameter of aggregates, Dg, and the overlap coefficient, Cov, of carbon nanoparticle aggregates produced by an ethylene diffusion flame and sampled by means of four commonly used techniques. The first method involves a thermophoretic piston probe (TPP) which inserts a TEM grid into the flame. Three other methods were applied at the outlet of a dilution device, also inserted in the flame. The first of these used a nuclepore filtration sampler (NFS), and is based on filtration of particles onto a polycarbonate membrane. The second, post dilution method, the insertion particle sampler (IPS), inserts a TEM grid, perpendicular to the aerosol flow. Similar to TPP, the last method is a thermophoretic particle sampler (TPS) sampling directly onto a TEM grid. After collection, the samples are stored in the dark either, (1) in a nitrogen filled cell at low humidity or, (2) in ambient air for ...