Our objective is to characterize gravity effects on the structure of laminar methane–air partially premixed flames through detailed simulations. We examine the heat loss due to radiation from similar flames that are established at various gravitational accelerations and coflow velocities. Radiation is modeled using the optically thin assumption that provides a limiting value for the radiation h...

In this study, the dependence of minimum ignition energies (MIE) on geometry, source radius and mixture composition is investigated numerically for methane/air iso-octane/air mixtures. Methane iso-octane are both important hydrocarbon fuels, but differ strongly with respect to their Lewis numbers. Lean air mixtures have particularly large The results show that within flammability limits, MIE st...

This paper reports on a combined experimental and modeling investigation of NOx formation in nitrogen-diluted laminar methane diffusion flames seeded with ammonia. The methane-ammonia mixture is a surrogate for biomass fuels which contain significant fuel-bound nitrogen. The experiments use flue-gas sampling to measure the concentration of stable species in the exhaust gas, including NO, O2, CO...

We investigated whether methane, ethylene and ethane gas can be detected in gas emanating from human skin, which is called skin gas. Skin gas was collected with a homemade stainless-steel trap system, which was cooled with liquid nitrogen, and analyzed with a gas chromatograph fitted with a flame ionization detector (FID). Skin-gas samples were obtained by covering a hand for 30 min with a poly...

One of the well-known properties of turbulent, premixed flames is that their speed of propagtion is correlated to the intensity of the turbulence they encounter. A simple consequence is that these types of flames are inherently unstable. Given a source of turbulence, if the flame is propagating faster than the mean flow, it will drift upstream and encounter increased turbulent intensities that ...

A theoretical–numerical analysis based on the second law of thermodynamics is used to examine the propagation of laminar H2-enriched CH4–air flames. The analysis is based on computing the various entropy generation terms in a transient reacting flow field. A comprehensive, time-dependent computational model, which employs a detailed description of chemistry and transport, is used to simulate th...

Soot concentration distribution is investigated both numerically and experimentally in methane-air diffusion flame. The experimental work is conducted with a cylindrical swirl stabilized combustor. Filter paper technique is used to measure soot volume fraction inside the combustor. The numerical simulation is based on the solution of the fully-coupled conservation equations for swirling turbule...

The flame propagation through a coal dust-air mixture in a spherical vessel was studied by means of a one-dimensional, Arrhenius-type kinetics and quasi-steady model. The model includes the evaporation of the volatile matter of dust particles into a known gaseous fuel (methane) and the single-stage reaction of the gas-phase combustion. Effect of venting devices as safety idea and the radiation ...

The oxidation of methyl formate (CH3OCHO), the simplest methyl ester, is studied in a series of burnerstabilized laminar flames at pressures of 22–30 Torr and equivalence ratios (U) from 1.0 to 1.8 for flame conditions of 25–35% fuel. Flame structures are determined by quantitative measurements of species mole fractions with flame-sampling molecular-beam synchrotron photoionization mass spectro...

For the case of flame thickness being of the order of the pore linear dimension, the flame structure and speed in adiabatic, premixed methane-air combustion in porous media are examined. The local, volume-averaged conservation equations that assume a local thermal equilibrium between the solid and the gas phases (i.e. the single-medium treatment) or allow for a thermal nonequilibrium (i.e. the ...