Bariza Zitouni

Experimental study of the energy balance of unheated greenhouse under hot and arid climates: Study for the night period of winter season

Abstract In regions with warm and hot climates as is the case of several countries of the Mediterranean basin, it is interesting to study the energy balance inside a greenhouse and to quantify the heat transfers along the building components (roof, walls and ground) in winter and during night time. The present experimental work was conducted in an unheated glasshouse without crop in the region of Batna, Algeria. Three types of measurements were done from January to March: the first one is at a cloudy night; the second one at a windy night and the third one at a cloudless night. The results indicate that the greenhouse ground is considered as a significant heat source which can compensate the energy losses through the walls especially during a night preceded by a significant diurnal insulation. In addition, the convection heat transfer coefficients inside and outside the greenhouse were estimated and analysed. A good agreement with the models reported in the literature was found.

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.

Numerical Simulation of Cavity with an Upper Free Surface

In this paper, 3D numerical study of Benard-Marangoni instabilities in a horizontal liquid layer for a Rayleigh number Ra = 0 and aspect ratio A = 20. The layer is heated from below and cooled from above (vertical temperature gradient). The upper surface is assumed to be free and non-deformable. The surface tension at the free surface is linearly dependent on the temperature. Silicon oil with Prandtl number (Pr = 880) has been used as a working liquid. A parametric study has been carried out by considering the following parameters: the thermal Marangoni number (Ma), the Biot number (Bi). The governing equations were discretized by the finite volume method. The resolution of the coupling (pressure-velocity) was done with the projection method. A code has been elaborated with FORTRAN 6.6. Velocity vectors and temperature fields on the upper free surface are obtained.

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.