Evaluation of Different Glazing Materials, Strategies, and Configurations in Flat Plate Collectors Using Glass and Acrylic Covers: An Experimental Assessment

Abstract

hail. transmissivity shortwaves but transmission thermal spectrum. The current study represents an experimental assessment of different covering strategies, including single acrylic-cover, single glass-cover, double glass- acrylic cover, and double glass-cover. Two solar air heaters (SAHs) prototypes were constructed for this study. The acquired experimental runs illustrated that the single glass-covered SAH represents higher thermal performance than the single acrylic-covered SAH due to the lower transmissivity of glass plates in long wavelengths. The double-covered SAHs have higher performance than the similar single-covered SAHs. In the double-covered SAHs, the convective-radiant heat loss is reduced. However, increasing the cover number improves the radiant resistance to solar irradiation and reduces the collector performance when solar irradiation is insufficient and the absorber temperature is low, especially at the beginning of daytime hours. The SAH using a double-glass cover is preferable; however, the heat dynamics of the double glass- acrylic-covered SAH are so close to the double glass-covered one, and the acrylic plate is more resistant to harsh ambient conditions.