Design & construction of a biomass powered onion curer.

Abstract

Onion (Allium cepa) is one of the most popular vegetable that make up daily diet. It is valued for its distinct pungent flavor and is an essential ingredient for cooking in many regions The onion curing machine was designed and fabricated consisting of four major functional units which included; combustion chamber, heat exchanger, suction unit, and drying chamber, with the components being connected. together by circular pipes for air delivery. The combustion chamber was a biomass filled cuboid container with conical head from where heat energy was generated. The heat exchanger conserved and preserved the heated air before being transferred to the drying chamber. The suction unit conveyed the heated air to the drying chamber: as the heated air passed Over the onions on the drying trays, drying was taking place by heat and mass transfer and the residual/exhaust air was exit through the chimney. The onion conditioner was evaluated based on its performance during no load and load tests. The source of energy was charcoal the average temperatures of the dryer and ambient were 3817 c c: and 26.5 0C respectively under no load. This shows a temperature increases above ambient providing a suitable onion curing conditions. During load tests, fresh Onions with an average initial moisture content of 86.0%wb was dried to average moisture content ranging from 74% to 77%wb within 4-5 hours. The performance of the dryer was evaluated in terms of its efficiency and the drying rate. Results obtained from the tests showed that conditioner efficiency was 21%. The drying rate was also found to be 0.16kg / hr.