Design, construction and testing of a banana juice extractor

Abstract

A banana juice extractor was designed, constructed and evaluated for performance using bananas (kayinja cultivar) and an extraction-aid-material; spear grass. The machine was designed to operate on the principle of compressive and shear squeezing force exerted through an impeller and tank with a half baffled configuration. The extractor consisted of the machine frame, motor housing, stainless steel impeller, stainless steel drum/tank, an AC single phase geared motor, and features responsible for the tilt feature of the machine. The design analysis of the components provided the data that was used in the sizing, fabrication and assembling of the machine. Performance tests were carried out using spear grass and peeled banana pulps that were introduced into the machine in different mixing ratios. The machine also had different tank configurations which were compared with the mixing ratios during the performance evaluation. The performance indicators considered were percentage juice yield (%) and extraction capacity (kgh-1). Results of performance analysis showed that differences in tank configurations and mixing ratios significantly influenced the performance indices at 5 % level of significance. The highest juice yield was 37.6% resulting from a half baffled tank configuration and a mixing ratio of 1:1 (palm/handfuls). Cut pieces of spear grass were used during the performance test and the size that was used to get to the yield 37.6% was approximately 0.1m. The extraction time for this yield was 0.25 hours hence an extraction capacity of 8.69kgh-1. To further improve the performance of the extractor, it was recommended to use baffles in a horizontal arrangement relative to the tank to increase the shear action as well as limit the swirling of contents.