Flow properties of African yam bean (Sphenostylis stenocarpa) as affected by accession and moisture content

Flow properties such as normal stress, shear stress, and initial shear stress, and hopper flow characteristics of two yam bean accessions (TSs 137 and TSs 138) were studied at four moisture content levels (4%, 8%, 12%, and 16% wet basis) to provide data for the design of handling and storage equipment. Two experimental designs were used: Randomized complete block design (RCBD) with one observation per cell, and split plot in RCBD. The initial shear stress increased with moisture content from 1.31 to 2.91 g/cm2 for TSs 137, while it increased from 1.58 to 3.09 g/cm2 for TSs 138. The hopper side wall slope for the two accessions increased with moisture content from 60.21° to 64.06°. The hopper opening size required increased with moisture content and more than doubled at the highest value of moisture content studied, while the coefficient of mobility decreased with moisture content from 0.33 to 0.24. The accessions were found not to be statistically different in terms of shear stress, coefficient of mobility, and side wall slope, but were statistically different in terms of normal stress, initial shear stress, and hopper opening dimensions. The methods of calculation of coefficient of mobility were observed not to be statistically different, and the effect of normal loads and type of hopper opening was highly significant. There was also a highly significant effect of moisture content on all the flow properties (p &le 0.05).