Studies on Sun Drying of Raw Rough Rice (Part 4)

Drying Characteristics and Solar Radiation on a Wavy Surface Layer

Abstract

Solar drying characteristics of a rice grain layer with wavy surface was studied. The wavy surface layers were either fixed with slanting surfaces facing East-West direction or rotated every hour to follow the path of the sun. For the fixed case, the maximum solar radiation received on the surface facing East was 760W/m² before noon and the surface facing West was 800W/m² in the afternoon. These values are approximately 1.3 times the maximum of 600W/m² on the plane surface. One day's change of solar radiation on the rotated wavy surface was nearly the same as plane surface layer, but the maximum was limited to 540W/m². The plane surface had the highest integrated solar radiation, followed by the fixed wavy surface and the rotated wavy surface. The drying rates in the three cases were 0.28, 0.30 and 0.29%/h, respectively. The relationship of solar radiation and drying was also investigated when the drying constant, k, was substituted for drying rate.