Abstract:
xvii
DESIGN, MANUFACTURING AND PERFORMANCE EVALUATION
OF ENGINE DRIVEN BARLEY DEHULLER
ABSTRACT
The conventional method of dehulling barley grains involves the use of milling machines or
pounding in a mortar with pestles, which can be costly and time consuming. To address this
issue, a batch type engine driven barley dehuller was designed and manufactured to efficiently
dehull barley grains. This machine operates on the principle of abrasion to remove the hulls of
the grains. Dehulling occurs through rubbing and friction generated by machine with a
rotating flat iron beater inside a dehulling chamber, combined with the friction between the
grains themselves as they move. The design and fabrication utilized locally sourced available
materials and technology, aiming to design, manufactures, test and evaluate the performance
of the barley dehuller. The study focused on the physical characteristics of barley grains and
assessed how independent variables like operational speed of the beater and hopper loading
affected dependent variables like dehulling efficiency, dehulling capacity, percentage of
damage and cleaning efficiency. The findings revealed that increased the operational speed of
beater from 900.00 to 1100.00 rpm and hopper loading from 5.00 to 11.00 kg/min
significantly enhanced dehulling efficiency, achieving maximum rates of 97.22 and 98.05%,
respectively. The higher centrifugal force at increased beater speed improved the separation
of bran from the grains, while greater hopper loading facilitated better grain flow. The
prototype dehuller demonstrated a dehulling capacity of 191.41 kg/hr. at the highest hopper
loading and beater speed of 11.00 kg/min and 1100.00 rpm respectively. However, it was
noted that higher beater speed led to a greater percentage of damaged grains, whereas
increased hopper loadings reduced grain damage. The maximum cleaning efficiency recorded
was 98.52% at 1100.00 rpm beater speed and a hopper loading of 11.00 kg/min. The dehuller
was designed to handle a maximum feed rate of grains that was 0.18 kilogram per second.
