Study of thermal radiative properties of antireflection glass for flat-plate solar collector covers

An analytical study is presented to evaluate thermal radiative properties of soda-lime sheet glasses covered with 0·087 μ m thick MgF₂ coatings. Glass specimens analyzed in the work consist of single and double layers of glass with either coated or uncoated surfaces. Equations for bulk and system properties are given which are used in conjunction with the measured absorption coefficient to determine glass spectral properties. Glass system properties are evaluated for five combinations of glass consisting of double layers of coated or uncoated glass plates. The evaluated spectral properties are integrated to yield total solar properties at different incidence angles. Analytical results show clearly there are advantages in using coated glass as solar collector covers; not only is the transmitted energy to the collector increased at normal incidence condition, but also the energy loss by reflection at large incidence angles is substantially reduced. This characteristic might be worthy of consideration in the future design of the flat-plate solar energy collector.