The physical properties of red gram were measured with respect to four moisture contents 10.08, 16.71, 21.37, and 25.59% d.b) of the grains. These properties are essential for design and development of post-harvest processing and storage equipment's such as harvesters, grain handling and conveyors, and storage bins etc. In the studied moisture range (10.08 to 25.59% d.b), the physical dimensions suchas length, width, thickness, and geometric mean diameter varied from 6.1 to 6.9 mm, 5.3 to 5.9 mm, 3.8 to 4.9 mm and 4.9 to 5.8 mm, respectively. The sphericity was not greatly affected by moisture content, while the surface area and seed volume increased from 77.47 to 107.38 mm2 and 79.25 to 109.9 mm3 respectively with increase in moisture content from 10.08 to 25.59% (d.b). The bulk density and true density decreased from 847.9 to 760.7 kgm−3 and 1301.7 to 1237.2 kgm−3 respectively, while the porosity increased from 34.85 to 38.51% with an increase in moisture content from 10.08 to 25.59% d.b. The terminal velocity increased from 7.58 to 11.13 ms−1 and emptying angles of repose also increased from 19.26° to 27.57° with an increase in moisture content. The coefficient of static friction of the redgram was highest against plywood surface (0.26–0.42) followed by galvanized iron surface (0.22–0.36) and stainless steel surface (0.18–0.31).
Physical properties, mechanical properties, red gram, moisture content, bulk density
