Ferahta Fatima

In order to study the effect of convection-radiation coupling occurring in the air gap of a solar thermal collector, numerical simulations were conducted for various thicknesses of the air gap with and without radiation. The studied geometry is a closed cavity which represents the confined space between the absorber and the glass. The cavity is inclined at an angle equal to 45 ° and is uniformly heated from below. The flow is three-dimensional and in unsteady state. First, the simulations were conducted considering only convection in the air gap, in this case the radiation is neglected and in a second time, the coupling between convection and radiation was taken onto account. In the first case the results show that the increase of the air-gap thickness leads to an intensification of the natural convection which develops from laminar, chaotic to turbulent regime. When the radiation is taken into account, the results show that the flow regimes are substantially modified, the convectio...

An experimental study was carried out to investigate the intensification of the efficiency of a flat solar collector. To achieve this aim, we investigated the effect of the thickness of the air gap between the glazing cover and the plate absorber and the effect of presence of transparent partitions in the air gap. Indeed, when the thickness of the air gap is increased, the natural convection is intensified, which induces high thermal losses on the front part of the collector. The result of this study highlights that thicknesses larger than the reference one, given by the manufacturer, decrease the efficiency, while thicknesses smaller than the reference one increase the efficiency. The presence of transparent partitions in the air gap leads to the weakening of the natural convection and thus to the enhancement of the solar collector efficiency. Two situations were studied. In the first one, only transverse partitions were placed in the air gap; in the second one, longitudinal partit...

An experimental study was carried out to investigate the intensification of the efficiency of a flat solar collector. To achieve this aim, we investigated the effect of the thickness of the air gap between the glazing cover and the plate absorber and the effect of presence of transparent partitions in the air gap. Indeed, when the thickness of the air gap is increased, the natural convection is intensified, which induces high thermal losses on the front part of the collector. The result of this study highlights that thicknesses larger than the reference one, given by the manufacturer, decrease the efficiency, while thicknesses smaller than the reference one increase the efficiency. The presence of transparent partitions in the air gap leads to the weakening of the natural convection and thus to the enhancement of the solar collector efficiency. Two situations were studied. In the first one, only transverse partitions were placed in the air gap; in the second one, longitudinal partit...