Effects of moisture content and grain variety on frictional properties and specific heat capacity of ACHA (Fonio) Grains

Abstract

There are many varieties of acha, but the most prominent two are white acha (Digitaria exilis) and brown acha (Digitaria iburua). This study was undertaken to determine the static coefficient of friction, kinetic coefficient of friction and specific heat of the grain as influenced by moisture content. The moisture content levels considered in the study were 5, 11, 23 and 28% db for the white variety and 5, 9, 21 and 30% db. The study revealed that increase in moisture content resulted to increase in the value of the properties considered for both varieties, with the white acha showing the highest values. Static coefficient of friction was increased linearly with moisture content and had maximum value on steel sheet (0.49 - 0.62) with its minimum on glass for the brown variety and (0.52-0.66) for the white variety with minimum on glass. Kinetic coefficient of friction increased  linearly with moisture content and the highest value was obtained on  hessian bag material (0.62-0.66) with the least being on steel sheet  (0.58-0.64). The study further revealed that, specific heat capacity of acha grains increased with increase in moisture content from 2.93 – 11.29 KJ/kgK (5 – 28% db) for the white variety and from 2.33 – 13.88 KJ/kgK (5 – 30% db) for brown variety. This study concludes that variety and changes in moisture content significantly affected the determined properties of acha.

Keywords: Acha, moisture content, coefficient of friction and specific heat capacity