Influence of glazing on the performance of flat plate solar collector

Abstract

Although flat plate solar collectors are widely used, the effects of multiple glazing layers and varying glazing thicknesses on their thermal performance remain poorly understood. This study uses computational fluid dynamics (CFD) through ANSYS Fluent to determine the optimal glazing configuration that maximizes solar energy absorption while minimizing heat loss. The analysis is conducted in two stages: first by varying the number of glazing layers, and then by adjusting glazing thickness, focusing on absorber plate temperature, top heat loss coefficient, and useful heat gain. The configurations studied for the number of glazing layers are 1, 2, 3 and 4 layers. The parameters such as the area of the collector, the gap spacing between the absorber, glazing and successive glazing, and the boundary condition of each components of collectors are maintained consistently throughout the study. The configuration with 2 glazing layers yields the highest temperature absorber plate, while having the second highest top heat loss coefficient and rate of useful heat gain among the configurations studied. The configuration with 2 glazing layers is selected for further study of glazing thickness. The configurations studied for glazing thickness are 2 mm, 3 mm, 4 mm, and 5 mm. The 4 mm glazing thickness for the two-glazing-layer solar collector configuration yields the highest absorber plate temperature, matching the temperature observed in the two-glazing-layer configuration from the glazing number study, as both used the same 4 mm glazing thickness. The configuration of collectors with double glazing with 4 mm glazing thickness can be considered the most balanced configuration that allows for efficient thermal performance, in term of solar radiation transmittance between glazing and heat retention within the air gap. This highlights the importance of a well-balanced configuration in the flat plate solar collector’s glazing, where a high absorber plate temperature can be achieved through trade-offs between thermal retention and energy output.