Performance Evaluation Of A Crossflow Column Drying System With A Biomass Burner Heat Source

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Grain drying is an important unit operation due to the vital role it plays in reducing grain loss and improving storability of grains. It is therefore, necessary to provide drying options which can easily be adopted by small-scale farmers in Ghana and other parts of sub-Saharan Africa. In view of that, this study assessed the technical and economic performance of a 500 kg capacity crossflow column dryer with a biomass burner heat source. The study applied the method of Analytical Hierarchy Process in the selection of an appropriate biomass burner which was incorporated into the drying system. System Thinking Approach was adopted in the development of a mathematical model to simulate the performance of the biomass burner. The model was validated with experimental results, which revealed an under prediction of burner efficiency by 4.06 %. 250 kg of maize at an initial moisture content of 22.30 % was used to assess the complete drying system and, its economic viability was appraised using Net Present Value (NPV), Internal Rate of Return (IRR), Payback Period (PBP) and Benefit Cost Ratio (BCR). The results of the study showed that per every 0.1 m increase in the length of heat exchanger, burner efficiency would have the capability to be increased by 20.4 % ± 1.34. Per the operating conditions presented in the study, drying rate and drying efficiency of 1.81 % and 64.65 % were achieved, respectively. The economic performance of the drying system also showed that for an operation period of 10 years, which represents the lifespan of the column dryer, NPV, IRR, PBP and BCR of GH¢ 8,094, 67 %, 1.48 yrs and 2.55 are anticipated to be achieved, respectively. From the results of the study, it can be inferred that the drying system could be adopted as a viable drying option by smallholder maize farmers in farming communities in Ghana.
A thesis submitted to The Department of Agricultural and Biosystems Engineering, Kwame Nkrumah University of Science and Technology, Kumasi in partial fulfilment of the requirement for the degree of MASTER OF PHILOSOPHY IN FOOD AND POSTHARVEST ENGINEERING