Effect of zone of chemical transformation on combustion rate of a condensed system

The problem of determining in practice the effect of a zone of chemical transformation on the combustion rate is discussed. Working relations are presented and their effectiveness is demonstrated on specific examples.     

Simulation of chemical transformation wave propagation through a flow reactor with a microbubble medium

A numerical simulation is carried out of the exothermal heterogeneous reaction of cumene oxidation on the basis of a homogeneous model of bubble liquid. The thermal properties of the bubble medium are determined according to the proposed model. The influence of different factors is investigated on an oxidation level with a volume gas content value of more than 0.5.     

Specific features of the behavior of synthetic diamond in a self-propagating high-temperature synthesis (SHS) combustion wave

The behavior of synthetic diamond powder in an SHS combustion wave is considered by using the model Ti-B-diamond system as an example. The results presented show that the diamond can retain its properties when exposed to the extreme thermal conditions realized in an SHS combustion wave.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 5, pp. 577–582, November, 1992.     

Some specific features of the combustion of silicon in nitrogen in the presence of organic additives

We have carried out an experimental study of the combustion of Si powders of different particle sizes in nitrogen in the presence of organic additives. The additives have been shown to initiate combustion, activate silicon transfer to the vapor phase, and contribute to the formation of a protective coating on the Si particles, which prevents them from coagulation when the temperature increases.     

Structure of the combustion wave in the combustion synthesis of titanium carbides

From the recorded images of combustion wave propagation during the combustion synthesis of titanium carbide, real time combustion velocities have been determined with increase of density of the compact. Results demonstrate that the combustion velocity exhibits a maximum with increase of density of the compact, and the wave propagates in a steady-state manner. Real time temperature profiles suggest that adiabatic conditions exist during the steady-state propagation of the combustion wave. Analysis of the images for the propagation of the combustion wave suggest that density plays a major role in the nature of propagation and whether the combustion wave propagates or not. Pore structural analysis of the carbides indicate collapse of the original porosity of the carbons, and the collapse of porosity is attributable to an exothermic diffusional reaction occurring between liquid titanium and carbon forming a titanium carbide product layer.     

Porous radiators with surface combustion in the filtration of a fuel-oxidant mixture

A method is proposed for calculating porous radiators with the injection of fueloxidant mixture, taking the influence of all the basic parameters into account.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 3, pp. 461–465, March, 1982.     

Laser-supported combustion wave in the field of gravity

Numerical simulation is used for studying the propagation of slow laser-supported combustion waves (LCW) in atmospheric air. The gasdynamic structure is investigated of the flow field which accompanies the movement of laser-supported combustion wave. A special feature of the problem being solved is the inclusion of gravity; this results in the emergence of convective motions in the thermal wake of LCW. It is demonstrated that different modes of thermal gravitational convection are observed depending on the conditions of LCW movement. A two-dimensional radiation-gasdynamic model is given, which includes the continuity and Navier-Stokes equations, the energy equation, and the equations of laser and thermal radiation transport in a multi-group approximation. The real thermal and spectral optical properties of air in the temperature range from 300 to 20 000 K are taken into account.     

Heat and mass transfer in the steady wall combustion of a filtrated gas mixture

The influence of external and internal heat and mass transfer on the temperature distribution in the solid and gas phases and on the stability of the combustion zone in standing-wave conditions is investigated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 51, No. 6, pp. 924–931, December, 1986.     

Relaxation combustion of gas mixture in a tube: Paradox piston motion

The pattern of the propagation of the propane-air flame front and a piston from a closed tube end to an open end that is investigated experimentally. It is shown that the tube length and the coefficient of the tube being filled up by a combustible mixture are determining conditions for generation of oscillations of the piston and the flame front. It is found that the velocities of the piston and the flame front are directed oppositely to each other in definite phases of oscillations. Gas oscillations in the tube trigger a relaxation combustion mode at which the velocity of the flame front effects a variation in the amplitude-frequency characteristics. The time dependences of a periodic variation in coordinates of the piston and the flame front are represented. A physical explanation of the phenomenon of mutual approaching of the flame front and the piston is proposed.     

Nonsteady-state interaction of a combustion wave with a dust cloud

A mathematical model of inhibition of gas flames by inert powders is studied.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 2, pp. 236–243, August, 1988.     

Heat and mass transfer in fluidized-bed furnaces in combustion of a coal-water mixture

The possibility in principle of burning highly ballasted fuel, including irrigated fuel, is considered. The permissible limits of the ash content and the moisture content are determined. The process of the thermal interaction between a drop of a coal-water mixture (CWM) and a fluidized bed is analyzed. Calculations of the distribution of volatiles and moisture in the fluidized bed in one-sided introduction of CWM are performed. The combustion of a CWM in a boiler furnace confirmed the practical possibility and expediency of recovering irrigated fuel waste of coal cleaning by this method. Ural State Technical University, Ekaterinburg, Russia. Translated from Inzhenerno-Fizicheski Zhurnal, Vol. 69, No. 6, pp. 993–999, November–December, 1996.     

Specific features of the gas-liquid mixture filtration

Summary The problem of an isothermic filtration of a gas-liquid mixture under pressure, exceeding the saturation pressure in a porous medium, is presented in the paper. Experimental results of the influence of the surface effect on the behaviour of the mentioned gas-liquid systems in the pre-critical area are also described here. It is demonstrated that increasing the wetting of the surface of the porous medium capillaries leads to the removal of the flow rate anomaly near the saturation pressure. Models to explain the observed effects occurring during the period of the gas-liquid mixture filtration when the pressure is higher than the saturation pressure have been offered.Notation P Static pressure - P _s Saturation pressure - P ₂,P ₁ Pressures of the inlet and outlet of the column with the porous medium - P _m Average pressure - P Pressure drop - P/l Pressure gradient - Q Flow rate of liquid - Q ₀ Liquid flow rate of Poiseulle-flow or flow rate by Darcy - Q/Q ₀ Relative flow rate of liquid - Q _m Maximum relative flow rate of liquid - Q ₁ Flow rate of the central layer of liquid - q Flow rate of liquid when flow is with slippage - Rate of fluid - ₀ Rate of filtration with slippage - Fluid viscosity - _C Apparent viscosity - l Length of the specimen of the porous medium - F Cross-sectional area of the specimen of the porous medium - m Porosity - K Permeability - R Capillary radius - R _C Average radius of pore channels - D Diameter of the porous medium particles - Gas-liquid mixture density atP - ₀ Gas-liquid mixture density atP _S - ₂, ₁ Density, according to gas-liquid mixture at the inlet and outlet of the porous medium - ₁, ₂ Minimum and maximum of the compressibility coefficient - V Volume of the sample - V Change of the sample volume - Dimensionless thickness of near wall layer - Ratios between the viscosities of the fluid layer in the central and at the walls of the capillary - C Surfactant concentration - C ₀ Nucleus concentration - b Slip coefficient - E _S Work of the heterogeneous formation of the gas phase nucleus - W Work of the homogenous formation of the gas phase nucleus - Contact angle between the liquid and the solid surface - f() Function of the contact angle - k Boltzmanns constant - T Absolute temperature - , , a _i , c _i Constant coefficients     

Some ground-state properties of a binary boson mixture

The optimal Jastrow wave function in the hypernetted-chain scheme is shown to generate numerically suitable expressions for the pressure and the compressibility of a binary boson mixture. In the single-component case, spin-polarized tritium is shown to be unstable for densities below 0.0044 Å^–3.     

Peculiarity of the effect of preheating the mixture on the pressure during combustion in a semiopen tube

Data are presented on the effect of the mixture temperature on the propagation of a flame in a semiopen tube. It is found that preheating of the mixture can increase or decrease the combustion intensity depending on the coordinate of the ignition source.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 31, No. 6, pp. 1097–1099, December, 1976.     

Concerning self-excited oscillations in frontal combustion of a fuel mixture in a resonator with lumped parameters

The conditions needed to stimulate harmonic self-excited oscillations in frontal combustion of a fuel mixture in the throat or cavity of a Helmhholtz resonator are considered. It is shown that they depend on the properties of the fuel mixture and the position and orientation of the front of the flame and can be satisfied only in the presence in the zone of combustion of a surface of discontinuity of the parameters that determine the rate of combustion. It is noted that the results of analysis do not come into conflict with the facts and dependences that are observed in combustion of fuel mixtures in tunnel burners, piston carburetors, and rocket engines.     

Thermal conductivity of a multicomponent gas mixture in the presence of equilibrium chemical reactions

Using methods of the thermodynamics of irreversible processes, an expression is obtained for the thermal conductivity of multicomponent gas mixtures.     

Controlling the position of a stabilized detonation wave in a supersonic gas mixture flow in a plane channel

Technical Physics Letters - Stabilization of a detonation wave in a stoichiometric hydrogen–air mixture flowing at a supersonic velocity into a plane symmetric channel with constriction has...     

Rapid degradation of metamitron and highly complex mixture of pollutants using MIL-53(Al) integrated combustion synthesized TiO2

In the present work, we report a new approach for the synthesis of TiO₂-MIL-53(Al) (MIL: Matériaux de l′Institut Lavoisier) nano-composite. The integration of microwave synthesized metal organic framework (MOF) with combustion synthesized metal oxide is reported for the first time. The synthesized materials were characterized using an X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscope, energy dispersive X-ray spectroscope, energy dispersive X-ray fluorescence, porosimeter, and UV–visible diffuse reflectance spectroscope. The diffraction pattern of the composite indicated the presence of TiO₂ as well as MIL-53(Al). Furthermore, the presence of anatase–rutile mixed phase of TiO₂ in the synthesized material was observed. The Fourier transform infrared spectrum was in support of XRD observations. A significantly low surface area and porosity of the composite material, compared to its parent components, was observed. The surface micrograph image of the composite depicted its nano-sheet type morphology. The energy dispersive X-ray analysis confirmed the presence of Ti, Al, C and O in the composite material. The composite material exhibited a narrow band-gap compared to the pristine MIL and TiO₂.As an application, the photocatalytic activity of synthesized material was determined by the degradation of metamitron. The application part is also one of the novelties of the present work. The effect of catalyst loading, initial concentration of metamitron and presence of inorganic ions on the photocatalytic degradation was investigated. The reusability of the composite material was evaluated. A plausible mechanism of photocatalytic degradation is proposed based on radical scavenging experiments. To the best of our knowledge, to date, there is no study on the application of TiO₂-MOF composite for the photocatalytic degradation of herbicide. Further, the synthesized material was successfully used for the photocatalytic degradation of a complex mixture of pollutants comprising metamitron, methylene blue, rhodamine B and 2, 4-dichlorophenol. This is a first of its kind study to demonstrate the application of TiO₂-MOF composite for photocatalytic degradation of a highly complex mixed pollutant.