S. A. Zhdanok

Engineering calculation of the characteristics of a filtration-combustion wave based on a one-dimensional two-temperature model

The authors present a method for determining the characteristics of a filtration-combustion wave that uses physically substantiated simplifications of a one-dimensional two-temperature model of filtration flow with Arrhenius kinetics. Explicit, physically transparent dependences for the ignition temperature, wave velocity, and maximum skeleton temperature are obtained. A brief review of and a comparison with other one-dimensional methods and with a numerical calculation are given. This method is shown to be superior to more cumbersome analytical two-temperature methods in accuracy.

OBTAINING SUPERADIABATIC TEMPERATURES IN COMBUSTION OF GASEOUS FUEL IN A SYSTEM OF TWO POROUS PLATES WITH A PERIODIC CHANGE OF THE DIRECTION OF PUMPING

A mechanism of obtaining superadiabatic temperatures in a system of two porous plates is theoretically investigated. Data on the optimum pumping periods and on the value of the produced superadiabatic effect are presented.

Cleaning of air of ethyl acetate impurity with the aid of a pulsed corona discharge

The study presents experimental data for cleaning of gas—air mixtures containing ethyl acetate (EA) impurities with the aid of a pulsed corona discharge. A test laboratory bench for investigating cleaning of flue gases is described. Dependences of EA conversion on the discharge parameters and on the temperature of the initial gas—air mixture and the content of water vapor in it are given.

Transition from the regime of low rates of filtration combustion of gases to the regime of high rates with a pressure increase

Regularities of the transition from the regime of low rates (RLR) of filtration combustion (FC) of gases to the regime of high rates (RHR) with a pressure increase are investigated. It is shown that allowance for gas-phase transfer is important for description of FC, at least when the size of the skeleton pores d>1.5–2.0 mm and the calorific power of the fuel exceeds the limit of propagation of the flame. With an increase of 1–2 atm in the working pressure as compared to atmospheric pressure the critical pore size decreases by a factor of 2.0–2.5. A theoretical model that makes it possible to evaluate the velocities and temperatures of FC stationary waves under conditions of the transition from RLR to RHR and to establish realization limits for these regimes is proposed. It is shown that a more adequate description of the transient regime and the regime of high rates is achieved when the turbulent character of the combustion is allowed for.

An approximate analytical solution of the problem of propagation of a filtration combustion wave in a porous medium

Within the one-dimensional single-temperature model, approximate analytical expressions are obtained for determination of the heat wave propagation velocity and the maximum temperature at the combustion front. The present results are compared with the results of the Zel’dovich - Frank-Kamenetskii asymptotic theory.

Simulation of the oxidation kinetics of NOx in a gas discharge

We investigate the mechanisms of the oxidation of NO in a gas discharge. We consider the influence of admixed water on the efficiency of removal of nitrogen oxides. Power expenditures are evaluated and optimal values for the temperature of a mixture and lifetime of particles in a reactor are found.

Possibility of methane decomposition in a gas discharge

The possibility of using a gas discharge such as a corona discharge or a barrier discharge for decomposition of methane in different gaseous mixtures is investigated theoretically. The effect of preheating of the gas to a temperature of 1200 K on the degree of methane conversion in the discharge is studied. A kinetic model that describes the processes of methane decomposition and oxidation in CH4/CO2, CH4/H2O, and CH4/O2 mixtures is developed. The effect of the discharge parameters and gas additives on the efficiency of methane decomposition is investigated. The optimum temperature of the mixture, particle lifetime, and initial concentration of oxygen for the production of hydrogen molecules are found.

Effect of the transparency of the skeleton on parameters of an axisymmetric cylindrical filtration combustion heater

Numerical simulation with a differential approximation of radiation transfer was carried out to study the effect of the partial transparency of the porous skeleton on the radiant efficiency, the maximum temperature, and the localization of the combustion front in an cylindrical axisymmetric filtration combustion heater. It is shown that the partial transparency of amorphous quartz grains for radiation provides a 2–5% increase in the radiant efficiency in comparison with nontransparent materials under the simulated conditions. It is shown that use of transparent fillings can both decrease and increase the skeleton temperature, depending on the size of the system and other parameters. Optical characteristics of porous fillings and models of radiation transfer in isotropic porous media are discussed.