DEPARTMENT OF MECHANICAL ENGINEERING

This report details the design, fabrication, and testing of a system for producing dry powdered akamu, a traditional Nigerian porridge made from fermented corn, sorghum, or millet. Akamu is an important dietary staple in Nigeria, however its high moisture content and short shelf life pose preservation challenges. Converting akamu to a dry powder form can extend its shelf life for storage and distribution. The aim of this project was to develop a process for producing preservable akamu powder. The device utilizes a vapor compression refrigeration cycle for air dehumidification coupled with electric heating to create optimal drying conditions. A control system consisting of an Arduino microcontroller which monitors and controls the operation of the device based off key operational parameters of temperature and humidity. Data on changes in said parameter was collected to evaluate its operation. Sample of akamu with a 53% moisture content (w.b) was successfully dried to 26% moisture content (w.b). Test also showed the device capability to rival available commercial dehydrators, with the device removed 3% more wet mass in its normal operation than when solely heat driven (as most commercial dehydrator). The relationship between akamu layer thickness and moisture removal rate was also experimentally determined. The project demonstrates a practical approach to converting high-moisture akamu into a stable powder through an energy-efficient drying process. Controlling air dehumidification and temperature enabled high product quality and shelf life extension. Further work is recommended to enhance efficiency, evaluate nutritional changes, and assess commercialization feasibility. Overall, the project advances preservation technologies for an important traditional Nigerian food

In Nigeria today and in the world at large, PET bottle waste has grown to become hazardous as it constitutes part of the non-biodegradable waste. Hence, recycling becomes necessary to curb its menace. This project work is centered on designing and fabricating a PET bottle crushing machine from locally sourced materials for both home and industrial use in an attempt to proffer solution to the PET waste problem in Nigeria. Preliminary tests and mechanical factors were extensively evaluated on the conceptual designs to ensure that the design that most suits the purpose was selected and detail design was carried out. Experiment to determine the power required to overcome the shear resistance of the PET bottles was carried out and it was discovered that 10hp at 450N was the power required. Finite element analysis was also performed on the cutting blade to inspect
the materials response to stresses and the corresponding deformation. Furthermore, a design study was carried out in order to ascertain the minimum and maximum loads that can be handled. Tests carried out on the machine showed its efficiency to be 82.2% which is only 6% less than the efficiency of foreign counterparts

Biogas presents a clean, renewable alternative to fossil fuels, capable of turning organic waste into a valuable energy source. However, the widespread adoption of traditional household digesters is hindered by a critical operational inefficiency: most systems operate in batches, requiring a prolonged downtime of up to 21 days for decomposition and reloading. This cycle makes them an unreliable and unsustainable energy source for daily use. This project addresses this core problem by aiming to design, fabricate, and test a mechanically optimized, easily refillable biogas digester that enables a truly continuous production system, thereby eliminating batch-processing delays. The methodology followed a systematic engineering design process, beginning with a feasibility study and the development of four distinct conceptual designs. A comprehensive conceptual design analysis, utilizing a weighted decision matrix, was carried out to evaluate these concepts against critical attributes like durability, safety, and ease of fabrication. The superior concept was selected for its robust continuous operation capability. This was followed by a detailed design analysis of the chosen concept, specifying all components, materials, and dimensions for a durable, vertical, cylindrical stainless-steel vessel. The design's key innovation is a dual-port feeding mechanism, featuring a top port for initial charging and a side-mounted manual rotary pump for continuous feeding. This design was then successfully fabricated to meet all intended specifications. Following fabrication, a hydrostatic test was successfully performed on the canister to verify its structural integrity and confirm it was completely sealed and leak-proof. With the vessel's integrity validated, the biological testing phase was initiated. The digester was charged with a buffered cow dung slurry feedstock to begin the anaerobic digestion process. The system is currently under critical observation, with the pressure gauge being continually monitored for positive readings, which indicate the successful onset of gas production within the sealed canister and validate the design as a practical, sustainable alternative.