Hocine Ben Moussa

Heat and mass transfer in a cylindrical grain silo submitted to a periodical wall heat flux

Abstract A grain silo is submitted to periodic and meteorologic influences: solar radiation, air temperature, wind. The heat transfer from the wall provokes a natural convective air flow and the grain out of equilibrium releases water. We consider heat and mass transfer in a cylindrical silo submitted to a uniform and periodic wall heat flux. The space under and above the bulk grain in the silo is free. A physical scaling of the problem leads us to build a dimensionless system of equations with three unusual numbers. An experimental study is carried out on a reduced silo filled with moistened mineral grain. The temperature and air moisture fields are investigated with thermocouples and sensors. Integration of equations allows us to evaluate natural convective velocity and quantity of water removed. Two flowing configurations are deduced: during the first half period, when the heat flux is high, the main part of the heat and mass transfer takes place in a boundary layer at the wall and this layer is fed with fresh air from the bottom and from the top through a central aspiration. During the second half period, when the heat flow is low, the stored heat provides a convective flux of a chimney type.

Inlet Methane Temperature Effect at a Planar SOFC Thermal Field Under Direct Internal Reforming Condition

In this work, an Anode Supported Planar Solid Oxide Fuel Cell (ASP_SOFC) is applied. The thermal fields are shown for a standard SOFC: yttria stabilized zirconia for the electrolyte, nickel/zirconia cermet for the anode, and doped lanthanum manganite (LSM) for the cathode. It is operating under direct internal reforming condition of methane gas.

Thermal field in SOFC fed by CH4: Molar fractions effect

Abstract In the present work, the anode supported solid oxide fuel cell (AS_SOFC) is fed by air and fuel at cathode and at anode channels respectively. The fuel is a mixture of five components: methane (CH4), hydrogen (H2), carbon dioxide (CO2), carbon monoxide (CO) and steam (H2O), where a reforming phenomenon; an external or an internal one appears. At the SOFC anode side, an indirect or direct reforming phenomenon happens.

Three-Dimensional Numerical Study of the Heat Transfer on The Planar Solid Oxide Fuel Cell: Joules Effect

The aim of this work is to analyze the three-dimensional temperature fields in a planar solid oxide fuel cell (SOFC) single cell with different geometric configurations: supported anode, electrolyte, or cathode (SA, SE, and SC). The temperature distribution is determined by taking into account only the largest heat source due to ohmic overpotential loss resulting from the Joule effect. The temperature values are obtained using a program in FORTRAN language which is based on the method of three-dimensional finite difference. The three-dimensional numerical study result analysis shows the localization of the highest temperature value at the SOFC component’s specific area: cathode (C), electrolyte (E), anode (A), and interconnector.

Three-dimensional numerical study of SOFC temperature field: Polarization heat source effect

This study represents the fields and the temperature profiles in a single cell of an anode supported planar a SOFC fuel cell under the influence of various polarization resistance sources; The Ohm polarization resistance type is at the anode, electrolyte, cathode and interconnector. The activation polarization resistance type at the electrodes (anode and cathode). The study is done at 3-D. The numerical simulation is performed by a FORTRAN program. The results are shown in the vertical plane passing through the channel center and parallel to the gas flow direction.

Thermal fields of a planar SOFC fed by methane: Steam reforming and water gas shift reaction effect

This paper presents an analysis of the heat source effect on the thermal fields of an anode supported planar Solid Oxide Fuel Cell (SOFC). Heat sources are: i) heat source due to the endothermic steam reforming reaction and ii) heat source due to the exothermic water gas shift reaction. This study is studied by a 2-D numerical simulation, in the plane perpendicular to the gases flow, and requires a coupling of transport phenomena of energy and mass species. The law of flow is governed by Darcys law. The gases are air and fuel. The inlet fuel is composed by a mixture of methane CH4, hydrogen H2, carbon monoxide CO, carbon dioxide CO2 and steam H2O. Results are obtained by developing a program in FORTRAN language using the finite difference method. The results show the inlet gases temperature effect on the SOFC thermal fields.