Some Moisture-Dependent Physical and Thermal Properties of Bambara Groundnut

Abstract

This study was carried out to investigate the effect of the moisture content on some physical and thermal properties of bambara groundnut (BBG) seeds. The properties were evaluated at five levels of moisture from11. 23 % to 28.11 % (wet basis). The average length, width and thickness were 12.10, 10.71 and 11.36 mm, at a moisture content of 11.23 %w.b., respectively. In the moisture range from 11.23% to 28.11% w.b., studies on rewetted BBG seeds showed that the unit seed mass increased from 1.115 to 1.634 g, the bulk density decreased from 795.25 to 781.87 kg/m 3 , the true density increased from 1193.00 to1226.11 kg/m 3 and the porosity from 34.53 to 43.07 %. The geometric mean diameter increased from 11.37 to 13.35 mm, the sphericity decreased from 0.97 to 0.93 % and surface area increased from 407.25 to 562.10 mm 2. The coefficient of friction on mild steel, plywood and aluminum sheet surfaces increased from 0.087 to 0.277, 0.09 to 0.0.407 and 0.078 to 0.384, respectively; the emptying angle of repose from 19.98 to 29.12, 23.00 to 32.89 and 24.39 to 39.29, respectively. The specific heat, thermal diffusivity and thermal conductivity increased from 1.70 to 2.17 kJ/kgK, 0.19 to 0.205 x 10-7 m2/s and .253 to 0.31 W/mK, respectively with increase in moisture content from11. 23 % to 28.11 % (wet basis). Empirical models were developed for all the parameters measured and their respective high correlation coefficients indicate that they can be used to simulate these parameters within the moisture domain investigated.