Moisture-Dependent Physical and Aerodynamics Properties of Cowpea Seeds

Abstract

This study focuses on the significant impact of moisture content on the engineering properties of cowpea seeds, which is vital for designing effective agricultural tools, equipment, and machines. We specifically examined two cowpea seed varieties, SAMPEA-16 and SAMPEA-14, across different moisture levels (10, 15, 20, 25, and 30% wb). Our findings show distinct variations in the physical characteristics of these seeds as the moisture content changes. For both SAMPEA-16 and SAMPEA-14, we observed changes in average length, width, and thickness at each moisture level. At moisture contents ranging from 10% to 30% wb, the dimensions for SAMPEA-16 were 11.20 mm by 9.10 mm by 8.61 mm, gradually changing to 10.60 mm by 8.80 mm by 8.50 mm, and for SAMPEA-14, they ranged from 8.30 mm by 6.50 mm by 6.50 mm to 8.40 mm by 6.50 mm by 6.40 mm. Significantly, the 1000 seed mass for SAMPEA-16 increased from 302.30 g to 404.80 g within the 15% to 30% moisture range, while the sphericity varied from 0.849 to 0.877. For SAMPEA-14, similar trends were observed with the sphericity shifting from 0.848 to 0.852. Additionally, the true density for SAMPEA-14 and SAMPEA-16 changed from 1034.12 kg m-³ to 1074.40 kg m-³ and 1089.61 kg m-³ to 1116.87 kg m-3, respectively. Another notable finding is the increase in the angle of repose with moisture content. For SAMPEA-16, it rose from 22.40˚ to 30.23˚, and for SAMPEA-14, from 23.22˚ to 34.28˚, as moisture content increased from 10% to 30%. Furthermore, the terminal velocity for both varieties increased with moisture, with SAMPEA-14 ranging from 4.92 to 5.25, and SAMPEA-16 from 5.72 to 6.16, at 10% to 25% moisture content. The insights from this study are crucial for the design of agricultural machinery, processing units, and storage facilities, aiming to enhance the quality and quantity of cowpea produce.