Transmission and forward scattering of insolation through plastic (transparent and semi-transparent) materials

Characterization of solar radiation transmission through plastic shading nets

“…Specifically, s was 0.02 for the black net and 0.14 for the green net, which are in good agreement with previously reported values for these colors [12]. The value of F R depended on the combined effect of color and porosity (e) of the net, which increased with increase in net brightness and decrease in e [ Fig.…”

“…This means that a fraction s of the transmitted beam (B t ) is diffused. The fraction s (called the scattering coefficient) is defined as the ratio of the beam radiation scattered diffusively during transmission to the total beam transmitted [12]. So, the measured diffuse transmitted radiation (D tot ) will include this portion (see Fig.…”

“…Transmission of solar radiation through nets is different from the transmission through transparent homogeneous covering materials such as plastic films, glass and rigid plastic sheets. The forward scattering and diffusion characteristic of solar radiation transmitting through homogeneous covering materials have been studied [12][13][14]. However, studies to examine these characteristics for plastic nets are not available.…”

“…Previous studies [12][13][14] assumed that a portion of the beam radiation transmitted through a transparent covering material scatters forward diffusively (diffused beams) and the remaining portion is transmitted directly (unscattered beams). This idea can be applied to homogeneous translucent materials.…”

Industrial and Agricultural Applications of Solar Heat

“…Although most plastic films have transmittances to visible light greater than 0.85, they exhibit very wide variations in transmittance to infrared from 0.01 for polymethyl methacrylate to 0.77 for polyethylene compared to 0.01 for glass. Some plastic materials exhibit translucent diffusion of incident direct-component insolation [15]. The major limitations of plastics are their poor physical stability at high water heating collector operating temperatures and their limited long-term durability primarily due to degradation under ultraviolet radiation.…”