A METHOD FOR MEASURING THERMAL-RADIATION PROPERTIES OF SEMITRANSPARENT MATERIALS

Films that are semi-transparent in the infrared are extensively used i n solar energy applications and agriculture. For analysing the perform ance of such systems, it is important to know the thermal radiation pr operties of these films. Whereas transmissivity can be determined easi ly, measurement of emissivity poses a problem. The intensity usually c onsists of radiation emitted from the film and transmitted background radiation. In this paper a method for determining the hemispherical to tal emittance, reflectance and transmittance of semi-transparent films simultaneously is presented. It has the distinctive features of simpl icity and high precision. The results for some transparent films are p resented.