http://hdl.handle.net/20.500.12283/346 Sat, 04 Apr 2026 00:28:33 GMT 2026-04-04T00:28:33Z http://hdl.handle.net/20.500.12283/4658 Design and fabrication a cold press avocado oil extractor Muyanja, Nicholas; Otim, Joshua The growing global demand for cold-pressed avocado oil—a premium product valued for its nutritional and cosmetic applications—offers a significant opportunity for smallholder farmers in Uganda. However, these farmers face considerable challenges, including high post-harvest losses (30–50%) and limited access to affordable and efficient processing equipment. This project addresses these issues by designing and fabricating a small-scale, energy-efficient cold press avocado oil extraction machine tailored to rural settings. The Design features a cylindrical malaxing chamber with modified paddles, a variable-speed motor for controlled mixing (15–30 RPM), and an optional heating jacket to maintain optimal processing temperatures (35–45°C). It also includes a screw press and an oil separation mechanism to enhance extraction efficiency while preserving oil quality. The methodology involves the design and fabrication of core components such as the pressing cage, gearbox, and feeding system, followed by prototype testing based on parameters like oil yield, energy consumption, and durability. This innovation aims to reduce post-harvest losses, improve value addition, and support the livelihoods of smallholder farmers. Furthermore, it contributes to Uganda’s Sustainable Development Goals by promoting poverty reduction, rural industrialization, and sustainable agribusiness development. Dissertation Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/20.500.12283/4658 2025-01-01T00:00:00Z http://hdl.handle.net/20.500.12283/4636 Design and modelling of an air conditioning system for Kayoola electric buses. Masede, Job The study aimed to design and model an air conditioning system for the 12 m Kayoola Electric Vehicle Solution (EVS) bus operating under Uganda’s tropical climatic conditions. The main objective was to develop, simulate, and validate an optimized AC system that enhances energy efficiency, passenger comfort, and driving range. The specific objectives were: (i) to design the AC system; (ii) to model and simulate the system thermodynamically to obtain optimum performance parameters; (iii) to evaluate field performance in terms of thermal comfort and energy consumption; and (iv) to assess the system’s financial viability. The research applied the HBM to compute the total cooling load, yielding 46.245 kW, with motor heat, radiation, and metabolic load contributing the largest share of cabin heat gains. The system was then modelled and simulated in Engineering Equation Solver (EES) software to analyse the vapour compression cycle performance, resulting in an optimum cooling capacity of 41.79 kW at an evaporator temperature of 11 °C. A multi-criteria decision analysis (MCDA) guided the selection of a variable-speed scroll compressor, brushless fans, an electronic expansion valve, and R134a refrigerant, which were integrated into a roof-mounted commercial variable-frequency AC unit. Field tests conducted under sunny and rainy conditions showed that the proposed system reduced specific energy consumption to 0.926 kWh/km, compared to 1.2916 kWh/km for the existing system, extending the driving range from 232 km to 382 km per charge. Cabin temperatures averaged 22.6 °C, maintaining comfort within ISO 7730 standards, with 96% passenger satisfaction recorded. Financial evaluation using the Federal Energy Management Program (FEMP) life cycle cost model revealed long-term savings of USD 18,929.25 over 20 years despite a slightly higher initial cost. The results confirm that a variable-capacity AC system, optimized for local climatic conditions, can significantly improve energy efficiency, passenger comfort, and operational economy of electric buses, supporting the advancement of sustainable urban mobility in Sub-Saharan Africa. Dissertation Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/20.500.12283/4636 2025-01-01T00:00:00Z http://hdl.handle.net/20.500.12283/4609 Feasibility study on densification of rice straw for briquette production Nambuya, Birah This study focused on the design, fabrication, and performance evaluation of rice-straw briquettes using locally available materials in Pallisa District, Uganda. The research aimed to develop a low cost, sustainable fuel alternative to charcoal and firewood by utilizing agricultural residues. The study followed an experimental research design where carbonized rice straw was combined with a composite binder made of cassava starch, clay, and molasses in ratios of 10%, 15%, And 20%. Briquettes Were produced using a hand-operated mold and compacted at forces of 0.16 kN, 0.22kN, and 0.31 kN. Mechanical and combustion properties including durability, compressive strength, bulk density, ignition time, burning rate, and calorific value were determined using standard procedures. Data were analyzed using mean ± standard deviation and graphical comparisons to assess performance differences among treatments. The economic analysis was conducted to determine production cost, market competitiveness, and potential charcoal substitution value based on the calorific value (14.74 MJ/kg) of the best-performing briquette batch. Results showed that increasing binder ratio and compaction force improved briquette strength, density, and energy value. The total production cost was estimated at UGX 500 per kg, while the selling price ranged from UGX 1,500–2,500 per kg, confirming profitability. Energy equivalence analysis indicated that 1 tonne of briquettes substitutes approximately 491 kg of charcoal, showing significant potential for reducing deforestation and improving rural energy access. Dissertation Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/20.500.12283/4609 2025-01-01T00:00:00Z http://hdl.handle.net/20.500.12283/4585 A solar powered food and crops drying system for utilization of refrigeration waste heat Namatovu, Ramizah; Ochwo, Kenneth; Kyomugisha, Jamie One of the main goals of the majority of cold chain operations is to decrease perishable post-harvest losses. Another useful technique for lowering post -harvest loss is drying. Nevertheless, the commercial drying methods currently in use require a lot of energy. High levels of greenhouse gasses are released during operation. Drying applications could make use of low-grade waste heat recovered from the refrigeration system's condenser. The technique involves the efficient use of heat that is intermittently produced by a refrigeration system's condensing unit with an external energy source of a solar collector that was used for drying during day as a source of heat to the condenser heat. The system was tested using cassava and tomatoes under various loading conditions, with performance assessed through temperature monitoring in both chambers, moisture content of cassava, and economic evaluation. An average temperature of 130C was maintained in the cooling chamber and for the drying chamber, a temperature of 32.0°C was used for the drying process at night and a 50.3°C during day time with combined heat from the solar collector and condenser heat. Results showed effective drying and cooling performance, reduced energy demand, and promising economic indicators, including a favourable net present value and internal rate of return. This proved to be a viable alternative to the comparatively more energy-intensive industrial drying technologies in use today. Dissertation Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/20.500.12283/4585 2025-01-01T00:00:00Z