Application of the physical properties of local cowpea varieties in the development of a multi-variety cowpea cleaner

Abstract

Cowpea, an annual legume widely grown and consumed in Nigeria, has been observed to contain between 27-33% impurities when freshly harvested and threshed. This poses a threat to humans when consumed and in largescale agricultural processing. Therefore, this study is aimed at developing and evaluating the performance of a multivariety cowpea cleaner (MVCC). Using standard methods, some selected engineering properties of the cowpea varieties were examined and used in the design of the MVCC. The cowpea had a moisture content of 8-14%, depending on the locations and varieties. Other properties investigated include the length, width, thickness, sphericity, geometric mean diameter, unit volume, arithmetic mean diameter, aspect ratio, surface area, unit weight, true density, terminal velocity, and angle of repose. The MVCC comprised the hopper, winnower, cleaning unit, fan assembly, and frame. The performance of the MVCC was also evaluated. The efficiency of separating good products of honey, drum, and Sokoto White beans was 95, 91, and 84%, respectively, while separating bad products was 87, 94, and 96%, respectively.