Simulation of the influence of design and meteorological factors on the efficiency of a solar plate collector
A mathematical model of heat transfer between the components of a solar collector and the surroundings is proposed. The model consists of the equations of heat balance for glass-covers, absorber and the rear side of a collector, as well as the heat transfer from the absorber to the heat carrying medium inside the collector. The heat balance equations take into consideration solar radiation, conduction, convection and infrared radiation between the components of the collector and its surroundings. Heat flow is calculated for solar collectors with two-glass and single-glass covers and the case where there is no cover. The subject of the investigation was to analyse the influence of different design characteristics (physical properties of materials, thickness of particular elements, distances between them) and parameters of surroundings on the efficiency of the collector. The optimal values of thickness of insulation and distances between the glass covers and the absorber, as well as other parameters were specified. The best conditions for using a collector with a double glass cover, with one glass cover and without any transparent cover were analysed. A solar collector performs better with a two-glass cover than with only a single-glass cover if the collector does not have a selective coating or if the temperature of the heat-carrier is high enough. This difference in performance, however, is not significant.
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