Determination of Solar Energy Absorption and Thermal Radiative Properties of some Agricultural Products

ABSTRACT THE average directional solar absorptance, hemispherical thermal emittance and collector efficiencies of flat-black paint and some agricultural products were determined experimentally by a calorimetric technique by using two similar flat-plate, air-cooled solar collectors. The solar absorption characteristics of these agricultural products was investigated with a view to designing simple crop dryers that use the products as solar energy collectors. Under identical conditions the following products were tested against solar energy absorptive capability of a standard metallic black plate collector: wheat, corn, black-eyed beans (cowpeas), brown beans, white and brown rice and in-shell peanuts. Of these agricultural products, only white rice was less than 80% as effective as a metallic black plate solar absorber. The implication of these finding is significant in drying, storing or preservation of foods, especially in developing tropical countries with hot and humid climates.