Effects of gas-solid nonequilibrium in filtration combustion

Wahle, Christopher; Matkowsky, B. J.; Aldushin, A. P.

doi:10.1080/00102200302357

Cited by 45 publications

(29 citation statements)

References 15 publications

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“…8-10 require modification by introducing separate energy equations for each phase. The model we use is an extension of that in [11], without some of its simplifying assumptions (in particular, we do not assume that the diffusion of heat in the gas phase is negligible): 3 Gas density, pressure and velocity profiles corresponding to Fig. 2.…”

Section: Heterogeneous Results: H Modelmentioning

confidence: 99%

“…It is important to note the following assumptions and comments about the model (11)- (14) (also see [11]):…”

Section: Heterogeneous Results: H Modelmentioning

confidence: 99%

“…(2) In our numerical examples the wave speed appears to be significantly increased by the production and movement of hot gas through the porous solid, which supplements the conductive preheating by both convection and the greater diffusivity of the gas. This, and other aspects of the wave propagation have been rigorously investigated in [11]. (3) The single temperature and dual temperature models give different predictions of the ignition time, with equality only in the limit μ → ∞ (infinite rate of heat exchange).…”

Section: Discussionmentioning

confidence: 99%

“…The results of that section will allow us to draw conclusions about the effectiveness of the PH model. (3) As in [3,4,[10][11][12][13][14][15][16][17][18] we neglect structural defects of the porous solid in our model. This allows us to focus on the effects of the gas movement, gas production and inter-phase heat transfer that leads up to the ignition event, after which structural deformation could occur.…”

Section: Model and Equations For A Single Temperaturementioning

confidence: 99%

“…Other related applications of FC include important processes such as smouldering and self-propagating high-temperature synthesis (see [10] and [11] for a review). Although much of the literature is concerned with the propagation of such waves, initiation problems have also received attention, [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Gas-phase and heat-exchange effects on the ignition of high- and low-exothermicity porous solids subject to constant heating

Shah

Brindley

McIntosh³

et al. 2006

J Eng Math

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This article investigates the ignition of low-exothermicity reactive porous solids exposed to a maintained source of heat (hotspot), without oxygen limitation. The gas flow within the solid, particularly in response to pressure gradients (Darcy's law), is accounted for. Numerical experiments related to the ignition of low-exothermicity porous materials are presented. Gas and solid products of reaction are included. The first stage of the paper examines the (pseudo-homogeneous) assumption of a single temperature for both phases, amounting to an infinite rate of heat exchange between the two. Isolating the effect of gas production and flow in this manner, the effect of each on the ignition time is studied. In such cases, ignition is conveniently defined by the birth of a self-sustained combustion wave. It is found that gas production decreases the ignition time, compared to equivalent systems in which the gas-dynamic problem is effectively neglected. The reason for this is quite simple; the smaller heat capacity of the gas allows the overall temperature to attain a higher value in a similar time, and so speeds up the ignition process. Next, numerical results using a two-temperature (heterogeneous) model, allowing for local heat exchange between the phases, are presented. The pseudo-homogeneous results are recovered in the limit of infinite heat exchange. For a finite value of heat exchange, the ignition time is lower when compared to the single-temperature limit, decreasing as the rate of heat exchange decreases. However, the decrease is only mild, of the order of a few percent, indicating that the pseudo-homogeneous model is in fact a rather good approximation, at least for a constant heat-exchange rate. The relationships between the ignition time and a number of physico-chemical parameters of the system are also investigated.

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Section: Heterogeneous Results: H Modelmentioning

confidence: 99%

“…It is important to note the following assumptions and comments about the model (11)- (14) (also see [11]):…”

Section: Heterogeneous Results: H Modelmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Model and Equations For A Single Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Gas-phase and heat-exchange effects on the ignition of high- and low-exothermicity porous solids subject to constant heating

Shah

Brindley

McIntosh³

et al. 2006

J Eng Math

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Asymptotic approximation of long-time solution for low-temperature filtration combustion

et al. 2012

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There is a renewed interest in using combustion for the recovery of medium viscosity oil. We consider the combustion process when air is injected into the porous medium containing some fuel and inert gas. Commonly the reaction rate is negligible at low temperatures, hence the possibility of oxygen breakthrough. In this case, the oxygen gets in contact with the fuel in the downstream zone leading to slow reaction. We focus on the case when the reaction is active for all temperatures, but heat losses are negligible. For a combustion model that includes heat and mass balance equations, we develop a method for calculating the wave profile in the form of an asymptotic expansion and derive its zero-and first-order approximations. This wave profile appears to be different from wave profiles analyzed in other papers, where only the reaction at the highest temperatures was taken into account. The combustion wave has a long decaying tail. This tail is hard to observe in the laboratory because heat losses must be very small for the long tail to form. Numerical simulations were performed in order to validate our asymptotic formulae.

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Pulsating linear in situ combustion: why do we often observe oscillatory behavior?

Bazargan

Kovscek

2018

Comput Geosci

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Effects of gas-solid nonequilibrium in filtration combustion

Cited by 45 publications

References 15 publications

Gas-phase and heat-exchange effects on the ignition of high- and low-exothermicity porous solids subject to constant heating

Gas-phase and heat-exchange effects on the ignition of high- and low-exothermicity porous solids subject to constant heating

Asymptotic approximation of long-time solution for low-temperature filtration combustion

Pulsating linear in situ combustion: why do we often observe oscillatory behavior?

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