8/12/2019 Munggo Sheller

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MUNGGO SHELLER: FOR SMALL SCALE MUNGGO PRODUCTION IN ROMBLON

By: Engr. Virne B. Dalisay, et. al

Faculty, Romblon State University

Chairman, Mechanical Engineering Department, RSU

Machine Technical Description

The Sheller is powered by a 1 horsepower electric motor as a given parameter since it is a

prototype and intended for small capacity. This was based also on design considerations of cost and

portability. The selection of different dimensions of the components and machine elements was based on

the given power capacity of the prime mover, 1-hp motor. The motors power is transmitted through a

belt and pulley transmission system to the shelling and cleaning units of the Sheller.

The shelling unit is composed and made of 9-mm square bar steel teeth welded on a frame

encircling the 1-in. diameter shaft. The 32 pieces, 3-inch teeth length are uniformly welded in a 3-inchdistance at right angle position. The teeth and shelling cover has a 5-mm clearance, slightly lower than the

average pod diameter. The cylinder cover is made up of a semi-circular 18-gage G.I sheet having a radius

of 7.5 inches perpendicular with the horizontal.

The cleaning unit is composed of an oscillating screen and blower assembly. The screen was

selected such that its holes are slightly larger than the munggo kernels. Actual measurement of the kernels

prompted the use of a screen with a inch diameter holes. This screen is attached to a tray where the

kernels and the shells are separated by the reciprocating motion of the tray. The oscillation of the tray was

achieved by attaching the tray in a cam mechanism machined in the shaft which is belt connected with the

shelling cylinder. A blower was included to address the presence of light impurities in the kernels during

the shelling operation. The initial setting for the blower speed was determined by observing the behaviorof the shells, kernels, and light impurities when air passes through them. To modify the air velocity

coming from the blower, the pulley attached to the blower shaft was iteratively chosen such that the

scattering and blower losses are minimized.

Performance Evaluation

The performance parameters determined during the tests include shelling efficiency, shelling

capacity, shelling recovery, input capacity, and total kernel loss. The total kernel loss consists of blower,

separation, unshelled and scattering losses.

The average shelling efficiency of the two trials of the machine based on the losses is 96.97%. It

measures the capacity of the machine to remove the kernels from the shell. On the other hand, the average

shelling recovery of the machine is 88.98%. It measures the efficiency of the machine when it comes to

the ratio of the cleaned kernel collected from the kernel outlet to the total kernel input of the Sheller.

The average input capacity of the Sheller machine is 113.6 kg/hr, or an equivalent 5 kg dried

munggo shelled in 2.6 minutes. For 1-hectare munggo farm production yielding almost 1100 kgs (1.1 tons

of munggo) can be shelled in at least 9.6 hr of continuous operation of the machine. Payback period is 2.5

years.