Marcelo J. S. De-Lemos

Temperature Distribution in Radial Porous Combustors

This paper presents two-dimensional numerical simulations of combustion of an air/methane mixture in a radial porous combustor using a model that explicitly considers the intra-pore levels of turbulent kinetic energy. Transport equations are written in their time-and-volume averaged form and a volume-based statistical turbulence model is applied to simulate turbulence generation due to the porous matrix. A cylindrical porous combustor is analyzed, in which the mixture flows inside it in the axial direction, being the flue gases ejected through the lateral surface. Combustion is modeled via a simple closure. For high excess air, the flame front moves towards the lateral exit of the burner. Also, increasing the inlet flow rate for stoichiometric mixture pushes the flame out of the porous material.Copyright

Passive Heat Transfer in Porous Enclosures Using a Two-Energy Equation Model

This paper presents computations for natural convection within a porous cavity filled with a fluid saturated permeable medium. The finite volume method in a generalized coordinate system is applied. The walls are maintained at constant but different temperatures, while the horizontal walls are kept insulated. Governing equations are written in terms of primitive variables and are recast into a general form. Flow and heat transfer characteristics are investigated for two energy models and distinct solid-to-fluid thermal conductivity ratio.Copyright

Simulation of Heat Transfer in a Counterflow Porous Bed Reactor With a Thermal Non-Equilibrium Model

The objective of this work is to study the influence of physical and geometrical properties on heat transfer between solid and fluid phases in a counter-flow porous bed, for cases where the fluid moves in opposite direction with respect to the permeable matrix. For simulating the flow and heat transfer, a two-energy equation model is applied in addition to a mechanical model. Transport equations are discretized using the control-volume method. The effects of solid-to-fluid velocity ratio, permeability, porosity, ratio of solid-to-fluid thermal capacity and ratio of solid-to-fluid thermal conductivity on flow and heat transport are analyzed. Results for a counterflow, that is similar to the heat exchangers in a countercurrent, indicate that there is more heat exchange for the smaller values of the parameters analyzed resulting in more uniform heat transfer between phases along the channel.Copyright

Simulation of Combustion in Porous Media With a Two-Energy Equation Model

This work presents numerical results for two-dimensional combustion of an air/methane mixture in inert porous media using turbulence and radiation models. Distinct energy equations are considered for the porous burner and for the fuel in it. Inlet velocity and excess air-to-fuel ratio are varied in order to analyze their effects on temperature and flame front location. The macroscopic equations for mass, momentum and energy are obtained based on the volume average concept. The numerical technique employed for discretizing the governing equations was the control volume method with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm was used to handle the pressure-velocity coupling. Results indicate that for high excess air values, the gas temperature peaks are reduced. Also, for the same conditions the flame front moves towards the exit of the burner. Results also indicate that the same flame front behavior occurs as the inlet velocity increases.Copyright