Numerical Simulation Investigation on the Optimum Air Layer Spacing between Absorber and Glass Cover in Flat Plate Solar Collectors with Small Convective Heat Loss

In this paper, Fluent is applied to predict the convective heat loss of the air cavity between absorber and glass cover of flat plate solar collector. Two-dimensional numerical models generally performed poorly to predict the heat transfer results at ¿<70° due to the intrinsic three-dimensional nature of the flow, three-dimensional modeling is applied and found to predict well the average heat transfer quantities. Results of the three-dimensional numerical simulation has been compared with literature ones, and they give a reliable agreements. The optimum air layer spacing of flat-plate solar collector was simulated with three-dimensional model and has got the result of about 50 mm at inclination of 0°, 30° and 45°and 20 mm at perpendicular case.