DEVELOPMENT OF A TIGERNUT SEEDS CLEANING AND SORTING MACHINE

Abstract

This study is about the development of a machine for cleaning and sorting of tiger nut seeds. Some selected physical properties of the tiger nut seeds such as size and shape, volume and density, surface area, weight, spherecity, coefficient of friction, angle of repose, as well as terminal velocity were also determined and used in the design of the machine. The average values obtained from the physical properties at 17 % moisture content are: surface area (206.12 mm2), geometric mean diameter (7.29 mm), spherecity (74.39 %), coefficient of friction (0.26) and angle of repose (25.40°) and terminal velocity of 17.60 mm/s of the tiger nut seed at moisture content of 17 % (wb). Based on the properties of the seed, a cleaning and sorting machine was developed that cleans and sorts the crop into size groups 12, 8, and 6 mm diameter. The machine was evaluated using the brown type tiger nut. The results of the ANOVA indicate that the sorting differs significantly with the three sieve diameters. The analysis also shows that the machine performed better at 12 mm diameter sieve compared to the other two sieve diameters. The developed machine has a throughput capacity and cleaning efficiency of 1.1 kg/min and 94.7 % respectively as against the manual cleaning of 0.22 kg/min and 18.94 % respectively.