Design of a Mini Rice Harvester for Rural and Small Scale Rice Farmers in Tropical and Developing Countries

Food insecurity, price volatility and under-employment of rice farmers in Liberia are key drivers for the development of rice farming machines locally. This project work aims to design and fabricate a simple, low-cost, efficient mini rice harvester powered by a solar panel by translating learnt concepts and principles of engineering into a physical and workable rice harvester. A circular blade cutter, DC motor, DC battery and solar cells are the main components deployed on a rod-plate setup. The solar cell taps solar irradiance from the sun and, with the help of a charge controller, recharges a 12V, 35Amp.hour battery. The battery supplies DC current to a DC motor that drives a circular blade cutter during harvesting. The fabricated harvester fulfilled all design objectives and was justifiable on overall financial cost (USD 194.00), ease of use, and ease of reproduction. The performance of the harvester, in terms of smoothness of cut and completion of cut area, was found to be near 100%. However, the harvester field efficiency performance was found to be 30.75% with an aggregated efficiency of % and a payback period of only 71 hours of operation, equivalent to 60,696 sq.m of harvested rice farm. Incessant clogged cutter's surface and harvested stem removal delays, slowdowns as the operator makes turns, switch failures and re-fix delays during field tests are the primary causes of the low field efficiency. With an improved spacing between the blade cutter and the secondary guard, the performance of the harvester is expected to improve significantly. An average noise level of 88.8 decibels was detected during the harvester's operation; advisably, hearing protection earmuffs may be necessary to safely operate the mini harvester on the dailies for 6 hours. Notwithstanding that the effect of moisture content of the rice stalks, as an input parameter, was not considered in the development of the power requirement for the rice cutter, the harvester can be optimized with minimal effort for commercialization and adopted as a Made-In-Liberia invention.