Effective scaled heat loss coefficient for translucent coatings of flat plate water-heating solar collectors

Abstract

We study how heat losses through translucent coatings are affected by the partial absorption and heat transformation of the total solar radiation passing through the transluscent coatings of flat plate water-heating solar collectors; the radiation is incident on the frontal surfaces of the translucent coatings of their casings and is reflected from the antireflective surfaces of the heat-exchange panels of diffuse solar radiation collectors; the radiation is incident on the rear surfaces of the considered translucent walls. To allow for this factor in thermal engineering calculations for the “antireflective heat-exchange panel-translucent coating” system of the considered type of flat plate solar collectors, we introduce the effective coefficient of heat loss from the antireflective surface of a heat-exhange panel via the given translucent coating. We propose a calculation technique and the corresponding formula for determining the effective heat loss coefficient through the transluscent walls of flat plate water-heating solar collectors and present a practical calculation example for determining its value.