Reflectance, Transmittance and Absorptance of HDPE, LDPE, Glass and Sand Layer Used in a SAH

Abstract

Abstract:The total Infra-red (IR) transmission of polymer films is a very important property in engineering, which determines their suitability for a specific application at a given temperature level. Aiming to investigate the percentage IR transmission of two polymer material films and glass of a particular thickness, an analysis is developed for the comparative evaluation of this very important physical property. Sand is a solid and a poor conductor of heat. That means that when sunlight hits sand, all the energy of the sunlight is absorbed in the first millimeter or so of the sand, the heat stays there or spreads only a few millimeters down. So those few millimeters get quite hot. High transmittance and absorptance of top cover and absorber plate are among the factors that contribute to the high efficiency of a SAH. Transmission and reflection spectra were obtained from the Spectro 320 Optical Spectrum Analyzer. IR Radiation (IR) was obtained from a lamp and measurements made at room temperature and relative humidity of 21°C and 25%RH respectively. The study shows that the transmittance of clear HDPE, LDPE and glass are 0.84, 0.72 and 0.72 respectively at wavelengths 791.90, 735 .02 and 820.89nm. The absorptance of sand layers was found to be 56% and 59% for grey and brown sand respectively.

Effect of Thermal Nanocomposite NiO/C to Scale up the Absorption of Solar Energy on Flat Plate Collector

“…The relation illustrates the transmittance start from the UV region as a 0.18 value and when it arrived at the visible region descended to zero value; this confirms that there is no transmittance in the Nanocomposite that utilized as a coating on the flat plate collectors and regard really as opaque materials. This Nanocomposite when precipitated on the substrate doesn't permit the electromagnetic wavelengths as a solar energy to transmitted through it [30,31].…”

Experimental Transmittance of Eva and Po Film Mulches

“…But the transmission properties of plastic films are different at different wavelengths. About the transmission of plastic films, a lot of researches have been carried out (Al-Mahdouri et al, 2013;Liang et al, 2020;Njoroge et al, 2014;Lozano et al, 2019;Baloccoa et al, 2018;Adelhafidia et al, 2015;Zhang et al, 2021;Jones et al, 2021;Al-Mahdouri et al, 2014). Njoroge et al (2014) measured the transmission and reflection coefficients of several PE films and glasses.…”