Upscaling for Adiabatic Solid–Fluid Reactions in Porous Medium Using a Volume Averaging Theory
نویسندگان
چکیده
In this paper, an upscaling study of solid–fluid combustion in porous medium with homogeneous and heterogeneous heat sources is carried out using a volume averaging theory. For the sake of simplicity, the reaction rate is assumed to be of first-order Arrhenius type and convection is not taken into account. Local thermal non-equilibrium is considered between the solid and fluid phases. During the resolution of closure problems, periodic boundary condition is utilized in order to determine the effective coefficients in the upscaled model.The obtained macroscale theory is validated against direct numerical simulation results for two typical porous medium geometries made of simple unit cells, namely unconsolidated and consolidated porous media. The comparisons between the present upscaled and microscale results are conducted for various Damköhler numbers for both homogeneous and heterogeneous reaction cases. It has been found that, for the low Damköhler number cases, the temperature profiles generated from the derived upscaled model are in accordance with that of the microscale model. For the high Damköhler number cases, however, the macroscale model fails to predict the combustion front and temperature profile, which evidently suggests that the effects of neglected terms during the upscaling process should be re-examined carefully in further investigations.
منابع مشابه
Upscaling of mass and thermal transports in porous media with heterogeneous combustion reactions
The present paper aims at an upscaled description of coupled heat and mass processes during solid–fluid combustion in porous media using volume-averaging theory (VAT). The fluid flows through the pores in a porous medium where a heterogeneous chemical reaction occurs at the fluid–solid interface. The chemical model is simplified into a single reaction step with Arrhenius kinetic law, but no ass...
متن کاملUpscaling Mass Transport with Homogeneous and Heterogeneous Reaction in Porous Media
The upscaling process of mass transport with chemical reaction in porous media is carried out using the method of volume averaging under diffusive and dispersive conditions. We study cases in which the (first-order) reaction takes place in the fluid phase that saturates the porous medium or when the reaction occurs at the solid-fluid interface. The upscaling effort leads to average transport eq...
متن کاملComparison of Thermal Dispersion Effects for Single and two Phase Analysis of Heat Transfer in Porous Media
The present work involves numerical simulation of a steady, incompressible forcedconvection fluid flow through a matrix of porous media between two parallel plates at constanttemperature. A Darcy model for the momentum equation was employed. The mathematical model forenergy transport was based on single phase equation model which assumes local thermal equilibriumbetween fluid and solid phases. ...
متن کاملDirect simulation vs volume-averaged treatment of adiabatic, premixed flame in a porous medium
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 ...
متن کاملNumerical simulation of a three-layered radiant porous heat exchanger including lattice Boltzmann simulation of fluid flow
This paper deals with the hydrodynamic and thermal analysis of a new type of porous heat exchanger (PHE). This system operates based on energy conversion between gas enthalpy and thermal radiation. The proposed PHE has one high temperature (HT) and two heat recovery (HR1 and HR2) sections. In HT section, the enthalpy of flowing high temperature gas flow that is converted to thermal radiation em...
متن کامل