H.O Egware

As global engineering practice increasingly prioritizes the elimination of greenhouse gas emissions and environmental pollution, the development of renewable energy-powered equipment represents a critical pathway toward sustainable industrial operations. This project focuses on the design and fabrication of a solar-powered grain grinding machine that harnesses photovoltaic technology to provide an off-grid, zero-emission solution for agricultural processing in rural areas where conventional electricity supply is unreliable and diesel-powered alternatives contribute significantly to carbon emissions and operational costs. The system employs a 350W brushless DC (BLDC) motor operating at 24V and 1500 RPM, powered by a 200W monocrystalline solar panel with battery backup comprising two 12V lead- acid batteries connected in series. A pulse width modulation charge controller regulates the charging process while providing comprehensive battery protection. The mechanical subsystem features a food-grade stainless steel hopper feeding into a burr-type grinding mechanism with 80mm diameter hardened steel grinding plates, enabling adjustable fineness control for various grain types. Power transmission from the motor to the grinding shaft is achieved through a universal joint coupling, with the complete assembly mounted on a fabricated mild steel frame. System performance analysis reveals a comprehensive energy conversion pathway from solar input to mechanical grinding output. The electrical subsystem demonstrates strong efficiency with the PWM charge controller achieving approximately 78% efficiency and the BLDC motor operating at 85-90% electrical-to-mechanical conversion efficiency. The mechanical drivetrain, comprising the universal joint, bearings, and shaft assembly, maintains approximately 85% transmission efficiency. These results in a net system operational efficiency of approximately 58% from battery DC output to mechanical grinding power. Under typical operating conditions, the system delivers approximately 315-320W of net mechanical grinding power from the 350W motor rating, accounting for motor efficiency and mechanical losses. Performance testing validated a grinding throughput of 5.0-10.0kg/hr for various grain types including tomatoes, pepper, millet etc with an estimated Specific Energy Consumption (SEC) of approximately 42Wh/kg. Environmental benefits include zero operational carbon emissions, elimination of air and reduced noise pollution, and contribution to sustainable rural development. The system eliminates recurring fuel costs associated with diesel generators, reduces monthly operating expenses for minimal maintenance, and provides payback periods of 1-3 months for small-scale commercial users.

Cavitation is a phenomenon that significantly impacts the performance, efficiency, and longevity of ship propellers, often leading to issues such as vibration, noise, erosion, and a reduction in propulsive efficiency. The motivation behind this study stems from the need to better understand the dynamics of cavitation bubbles and their effects on propeller performance to design more efficient and durable marine propulsion systems. As cavitation can cause damage to propeller blades and reduce fuel efficiency, addressing this issue is crucial for the advancement of ship design, particularly in terms of material selection, propeller geometry, and operational strategies. The purpose of this research is to analyze the effect of cavitation-induced bubbles on ship propellers using advanced computational tools, thereby providing insights that could guide future propeller designs and enhance maritime operational efficiency. To achieve this, the study employs ANSYS simulation tools, specifically its Computational Fluid Dynamics (CFD) module, to model and simulate the behavior of cavitation bubbles in proximity to the propeller. The simulations use a multiphase flow model that includes both the liquid and vapor phases, allowing for the simulation of bubble formation, growth, and collapse under various operating conditions using the vp1304 as the propeller model. The study examines different parameters such as propeller rotational speed, fluid velocity, water temperature, and turbulence levels. The simulation environment is built on realistic physical conditions, using detailed mesh generation to accurately capture the complex flow behavior round the propeller blades. ANSYS Fluent's cavitation model is used to simulate bubble dynamics, with a focus on evaluating pressure distributions, vortex shedding, and velocity gradients. The results of the simulations reveal that cavitation has a profound effect on the hydrodynamic performance of the propeller. Areas of the propeller subjected to low-pressure conditions were found to experience intense cavitation, leading to significant performance degradation, including thrust loss, decrease in torque, decrease in the overall efficiency of the model. Additionally, the simulations suggest that optimizing propeller blade shape and operating conditions could mitigate the detrimental effects of cavitation. The findings highlight the importance of considering cavitation dynamics during the design phase and provide a roadmap for improving propeller efficiency, reducing cavitation damage, and enhancing the overall performance of marine propulsion systems.

A significant problem in Nigeria is limited access to electricity, particularly in rural areas, which creates an over dependence on fossil fuel generators as alternatives which is environmentally damaging. A cleaner alternative is hydropower, and Nigeria has potential for developing it, as the country has multiple water sources necessary for hydropower. One of these sources which has not been exploited is rain water runoff from roofs. However, majority of these sources only possess low- flow, moderate-head conditions, which do not fit the requirements for the largescale nature that existing hydroelectric projects are already designed for. Hence, the motivation for this project is the need to explore an alternative to fossil fuel power generation, that exploits these low-flow, moderate-head conditions, thus solving the problem of unreliable, high-cost power. Therefore, this study is aimed at designing, fabricating, and testing a micro-scale Pelton wheel turbine system, that can operate by roof runoff, using locally sources materials. The system was based on an experimentally determined design runoff flow rate of 0.4167 L/s, that was gotten from a selected suitable building, and simulated using an 80L drum at a 2.0 m head which was provided by a wooden stand. The system was fabricated using locally soured materials including a steel frame, thermoformed plastic buckets, a 3W 6V hub motor, a rectifier, a display unit, current and voltage sensors, and a bulb among other. The system’s display unit
was calibrated with flowrate readings, and that in collaboration with its power reading by the voltage and current sensors, were key to the system’s testing procedure.

Enhancing the thermal performance of building envelopes is crucial for improving energy efficiency and indoor comfort. This study examines how different material combinations influence heat transfer through composite walls. To achieve this, we conducted both theoretical calculations and ANSYS simulations, analyzing various wall configurations. The study focused on steady-state heat transfer, considering conduction and convection while neglecting the first convective resistance. We tested multiple material setups, including Dense and Medium Dense Hollow Concrete Blocks, Fiber Glass Insulation, Rock Wool, Polystyrene Foam, Air Cavity, Agba Wood, and Mahogany. The analysis was carried out under controlled conditions, with an outer surface temperature of 35°C, an inner fluid temperature of 25°C, and a convective heat transfer coefficient of 25 W/m²·K at the inner surface. Our findings offer valuable insights into selecting materials that can optimize building envelopes, reduce heat transfer, and enhance indoor thermal comfort. This research contributes to the development of more energy-efficient and sustainable building designs