Filtrational combustion of gases. Present state of affairs and prospects

Babkin, V. S.

doi:10.1351/pac199365020335

Cited by 170 publications

(51 citation statements)

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“…Babkin [21] referred to this as the 'low-velocity detonation' regime. This is a misnomer since propagation in this regime is not restricted to detonation waves.…”

Section: Discussionmentioning

confidence: 99%

“…The propagation regimes are typically categorized based on the magnitude of the combustion front velocity, e.g. low velocity, high velocity, sound velocity, lowvelocity detonation and detonation regimes [21]. The explosion front propagation mechanism for each regime is different and is governed by the relative importance of inter-phase heat-transfer, turbulence and compressibility effects.…”

Section: Combustion Wave Propagation In Porous Mediamentioning

confidence: 99%

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Explosion propagation in inert porous media

Ciccarelli

2012

Phil. Trans. R. Soc. A.

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Porous media are often used in flame arresters because of the high surface area to volume ratio that is required for flame quenching. However, if the flame is not quenched, the flow obstruction within the porous media can promote explosion escalation, which is a well-known phenomenon in obstacle-laden channels. There are many parallels between explosion propagation through porous media and obstacle-laden channels. In both cases, the obstructions play a duel role. On the one hand, the obstruction enhances explosion propagation through an early shear-driven turbulence production mechanism and then later by shock-flame interactions that occur from lead shock reflections. On the other hand, the presence of an obstruction can suppress explosion propagation through momentum and heat losses, which both impede the unburned gas flow and extract energy from the expanding combustion products. In obstacle-laden channels, there are well-defined propagation regimes that are easily distinguished by abrupt changes in velocity. In porous media, the propagation regimes are not as distinguishable. In porous media the entire flamefront is affected, and the effects of heat loss, turbulence and compressibility are smoothly blended over most of the propagation velocity range. At low subsonic propagation speeds, heat loss to the porous media dominates, whereas at higher supersonic speeds turbulence and compressibility are important. This blending of the important phenomena results in no clear transition in propagation mechanism that is characterized by an abrupt change in propagation velocity. This is especially true for propagation velocities above the speed of sound where many experiments performed with fuel-air mixtures show a smooth increase in the propagation velocity with mixture reactivity up to the theoretical detonation wave velocity.

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“…Babkin [21] referred to this as the 'low-velocity detonation' regime. This is a misnomer since propagation in this regime is not restricted to detonation waves.…”

Section: Discussionmentioning

confidence: 99%

Section: Combustion Wave Propagation In Porous Mediamentioning

confidence: 99%

Explosion propagation in inert porous media

Ciccarelli

2012

Phil. Trans. R. Soc. A.

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“…The problem of gas combustion in inert porous media has been studied intensively both theoretically and experimentally. The most important results of both research methodologies have been summarized in [8,9]. One of the most important problems of porous media burners is stabilizing the flame in a specific zone of the inert porous media.…”

Section: Introductionmentioning

confidence: 99%

Filtration Gas Combustion in a Porous Ceramic Annular Burner for Thermoelectric Power Conversion

Bubnovich

Martin

Henríquez

et al. 2018

Heat Transfer Engineering

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A numerical study of the combustion of lean methane/air mixtures in a porous media burner is performed using a novelty geometry, cylindrical annular space. The combustion process takes place in the porous annular space located between two pipes, which are filled with alumina beads of 5.6 mm diameter (Al 2 O 3 ) forming a porosity of 0.4. The outer tube diameter of 3.82 cm is isolated; meanwhile the inner tube of 2 cm in diameter is covered by a continuous set of thermoelectric elements (TEE) for transforming heat energy into electricity. To achieve and maintain the proper temperature gradient on TEE, convective heat losses are considered from the TEE. The respective heat transfer coefficient is variable and is in the range 800 < h < 1500 [W / m 2 ]. The 2D mathematical model includes the energy equations for solid and gas phases, the momentum equations, the continuity equation, the fuel mass conservation, the perfect gas law and it is solved by Means of computational simulations in COMSOL Multiphysics. Computer simulations focus on the two-dimensional temperature analysis and displacement dynamics of the combustion front inside the reactor, depending on the values of the filtration velocity (0.1 < u g0 < 1.0, m/s) and the fuel equivalence ratio (0.06 < Φ < 0. The study shows that the cylindrical annular geometry can be used for converting the energy of combustion from lean gas mixtures into electricity, with a performance similar to the specified by manufacturers of TEEs. INTRODUCTIONThe need to lower emissions and increase efficiency in fossil fuel combustion has driven the search of new combustion methods and advanced burner designs. A porous media burner can provide a good solution due to a number of advantages compared to conventional free-flame combustion, such as large power variation range, high efficiency, compact structure with very high energy concentration per unit volume, extremely low CO and NO x emissions over a wide range of thermal loads, stable combustion over a wide range of equivalence ratios, 0.4 < Φ < 0.9 [1][2][3]. All the arguments mentioned above have driven the current development of these kinds of burners, which have already found several important industrial applications [4-

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“…Stationary and transient systems are the two major design approaches commonly employed in porous combustion [2][3][4][5][6][7][8]. The first approach is widely used in radiant burners and surface combustor-heaters where the combustion zone is stabilized within the finite element of the porous matrix.…”

Section: Introductionmentioning

confidence: 99%