Design and construction of a motorized multi-grain cleaner.

Abstract

Grains contribute an important element in food industry and food security in Uganda. They tire consumed in homes schools, hospitals among the armed forces, rehabilitation centers, refugee camps institutions, health centers clue to the large quantity of carbohydrates, proteins. Vitamins and fats contained in the kernels. According to FAO 10% grain losses occur due to poor post-harvest handling. Harvested grains have straw, chaffs and rocks, dust, damaged seeds stones cobs husks and many others. The foreign matter in grains adversely affects subsequent storage and processing conditions affecting the nutritional and market value. Cleaning by traditional winnowing technology leaves the grain contaminated with foreign matter posing a reduction in farmer's income. Small holder farmers in Uganda use traditional post-harvest handling methods that expose grain to contamination by foreign matter. Manually grain cleaning methods are in efficient, labor intensive and depend on natural wind which leaves the grain contaminated. To overcome this problem this study chose as its main objective to design and construct a multigrain cleaner as well as testing of the constructed machine find the economic evaluation of the multigrain cleaner. It is aimed to enable the small holder farmers to enhance the quality and quantity of their consumable grain and enhancing the nutritional and market value, with significant reduction in the quantitative post-harvest losses thus enhancing the country's food security status. The grains considered in this study were rice, sorghum and maize. Various components of multigrain cleaner were designed using basic engineering principles and some physical properties of grains such as size, density (760kg/m3,); moisture content (7.6% dry basis), angle of repose, (29.5°) and weight of the grain. The trays, sieves perforations were obtained to be 12mm and 4.0mm for first and second sieves respectively. The performance of the multigrain cleaner was evaluated in terms of machine output, cleaning efficiency, cleaning loss and mechanical damage for machine output. The machine was found to be viable after the economics analysts with a projection of three years. Addition of a cyclone for preventive collection of chaff during cleaning was recommended to prevent pollution of the environment.