DEPARTMENT OF MECHANICAL ENGINEERING

The problem of electricity in Nigeria has become some sort of a nationwide pandemic that has plagued the country for years and continues to do so. With seemingly no end in sight to the electricity crisis, food storage has become very expensive as individuals as well as producers need to pay a lot of money to run generators to power refrigerators. An alternative means to this would be a more than welcomed development. This project aims to reduce the cost encountered in refrigeration by using vapor absorption refrigeration which is powered by solar energy.

The vapor absorption refrigerator uses water as its refrigerant, and zeolite is used as the absorbent. The compression system is a network of systems consisting of an absorber and a generator; aimed at compressing liquid refrigerant-absorbent mixture which requires less work to compress than vapor. The temperature of the evaporator, generator and condenser were measured and recorded periodically. The performance of the system is evaluated as the ratio of heat removed from the refrigerated space to the heat added to the system at the generator.
The refrigerator proved quite functional, achieving a COP of 0.66. This validates the functionality of the system but it was observed that it took 3 hours of heating to produce a 9°c drop (from 34.2°c to 25.2°c) in evaporator temperature. After 5 hours of heating, there was a 15°c drop (from 34.2°c to 19.2°c) in evaporator temperature. However, the atmospheric temperature was 27°c which means the cooling achieved was not appreciable. The system used in this project suffered from a lot of leakages and heat loss which directly affected the performance of the system. We recommend that further studies on techniques which would prevent heat loss and meticulous fabrication process to prevent leakages allow. Significant reduction in heat loss would greatly improve the performance of the waste solar powered VARS thereby making it more viable and suitable for domestic and commercial usage

A study was carried out based on societal use of electric power for the purpose of domestic cooking resulting in the observation that a substantial number of households do, occasional or seriously use electric power for cooking through heat generating electric stoves. An ensuing market survey around Benin City also revealed that various brands of electric cooking stoves are being sold in the markets. A close observation further revealed that virtually all the brands on sale in the markets are imported and are quite expensive. Based on these findings the idea of providing a locally fabricated alternative for these foreign brands of electric cooking stove was conceived and it led to the execution of this project. An extensive study of used and broken electric stoves as well as an extensive literature review showed that it is possible to design and fabricate from locally available materials, with the
purchase of just two of the main components, the heating element and the thermostat. With this understanding, basic engineering knowledge was then applied to design all the components of a basic electric cooking stove. The components included the Frame, the Heat Generating Compartment, the Support Ceramic for the heating element, the Heating Element, the Internal Wiring, the Thermostat and the External Wiring and Plug. The designed components were fabricated and assembled to produce the electric stove which was tested and found to operate to a very high level. The main findings from this project work shows that the unit fabricated was not only more affordable, it was more sturdy and able to support cooking pots larger than what the imported brands could support. The design was also made to generate higher temperatures that leads to faster cooking thus balancing the total cost of power usually needed to cook the same amount of food.

A study was carried out based on societal use of electric power for the purpose of domestic cooking resulting in the observation that a substantial number of households do, occasional or seriously use electric power for cooking through heat generating electric stoves. An ensuing market survey around Benin City also revealed that various brands of electric cooking stoves are being sold in the markets. A close observation further revealed that virtually all the brands on sale in the markets are imported and are quite expensive. Based on these findings the idea of providing a locally fabricated alternative for these foreign brands of electric cooking stove was conceived and it led to the execution of this project. An extensive study of used and broken electric stoves as well as an extensive literature review showed that it is possible to design and fabricate from locally available materials, with the purchase of just two of the main components, the heating element and the thermostat. With this understanding, basic engineering knowledge was then applied to design all the components of a basic electric cooking stove. The components included the Frame, the Heat Generating Compartment, the Support Ceramic for the heating element, the Heating Element, the Internal Wiring, the Thermostat and the External Wiring and Plug. The designed components were fabricated and assembled to produce the electric stove which was tested and found to operate to a very high level. The main findings from this project work shows that the unit fabricated was not only more affordable, it was more sturdy and able to support cooking pots larger than what the imported brands could support. The design was also made to generate higher temperatures that leads to faster cooking thus balancing the total cost of power usually needed to cook the same amount of food.

This report details the design and implementation of an electric-solar vehicle,
focusing on the fabrication and testing of its inverter. The inverter, a crucial
component for efficient power conversion, was developed to optimize the
integration of solar energy with an electric motor drive. This report focuses on the
practical aspects of the inverter's construction and performance evaluation.
The design considerations are outlined, followed by a detailed description of the
component selection, PCB fabrication, and assembly. Performance testing results,
demonstrating the inverter's efficiency and suitability for the vehicle, are also
included.

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.

A study was carried out based on societal use of electric power for the purpose of domestic cooking resulting in the observation that a substantial number of households do, occasional or seriously use electric power for cooking through heat generating electric stoves. An ensuing market survey around Benin City also revealed that various brands of electric cooking stoves are being sold in the markets. A close observation further revealed that virtually all the brands on sale in the markets are imported and are quite expensive. Based on these findings theideaof providing a locally fabricated alternative for these foreign brands of electric cooking stove was conceived and it led to the execution of this project. An extensive study of used and broken electric stoves as well as an extensive literature review showed that it is possible to design and fabricate from locally available materials, with the purchase of just two of the main components, the heating element and the thermostat. Withthis understanding, basic engineering knowledge was then applied to designall thecomponents of a basic electric cooking stove. The components included the Frame, the Heat Generating Compartment, the Support Ceramic for the heating element, the Heating Element, the Internal Wiring, the Thermostat and the External Wiring and Plug. The designed components were fabricated and assembled to produce the electric stove whichwas tested and found to operate to a very high level. The main findings from this project work shows that the unit fabricated was not only more affordable, it was more sturdy and able to support cooking pots larger than what the imported brands could support. The design was also made to generate higher temperatures that leads to faster cooking thus balancing the total cost of power usually needed to cook the same amount
of food.

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.

Over the years there’ve been need to transition from fossil fuel into cleaner forms of energy as a result of the detrimental effect the burning of fossil fuel has on the environment. The storage related issues of hydrogen are some of the challenges limiting its exploration as a cleaner energy source. Specifically, compressed form of hydrogen storage which is the most adopted method of storing hydrogen faces various challenges such as the hydrogen embrittlement of steel and loses of structural integrity over the course of usage.This study is aimed at addressing this issue by exploring two configurations and comparing them to the conventional all alloy steel configuration. The two configurations (HDPE, Carbon fiber configuration(H-C) and carbon fiber, HDPE, carbon fiber configuration(C-H-C)). were investigated for performances characteristics at various pressure levels and compared to the all-alloy steel configuration. At a pressure of 15Mpa, the H-c configuration had a stress value of 7.89E+07N/mm while the C-H-C configurations had a stress value of 1.05E+08N/mm. various parameters including stress, displacement, strain, and factor of safety for the two configurations were investigated and compared to the all-alloy steel configuration. The two configurations should good performance for various pressure values. However, the carbon fiber, HDPE, carbon fiber configurations should the closest performance to the all-alloy steel configurations, with the factor of safety almost equal for pressure values above 35Mpa.Suggesting that the Carbon fiber, HDPE, Carbon fiber to be a good alternative to the all-alloy steel as it address the hydrogen embrittlement issue without compromising structural integrity.

The purpose of this project is to design a small-scale biogas digester that uses household food waste as feedstock to address the financial and environmental issues that arise from food waste. The aim is to reduce dependency on fossil fuels by producingbiogas from biodegradable waste, which can be used for power generation and cooking. A review of the literature, conceptual design, meticulous manufacturing, and performance testing are among the goals. The study emphasizes how important it is to address rising food waste to improve the environment and provide financial relief. The project's goal is to make it easier for homes to adopt biogas plants by offering ideas that are simple enough for installation. The scope includes designing and building a biogas canister digester as well as producing biogas from home food waste.

The previous system which had a 3.5KVA, 48V inverter, eight(8) 12V, 220AH wet cell batteries and eight(8) 150W, 24V solar panels was disconnected. A new inverter which is a hybrid inverter of rating 7.5KVA, 48V was purchased alongside with four(4) 12V, 220AH wet cell batteries. The panels which were placed on the roof 500m from the stationary unit was cleaned up with wet rags and mild detergent, and the eight(8) old batteries were cleaned up and revamped by addition of distilled water and the batteries were arranged in three(3) frameworks (four to each). A framework containing the four(4) new 12V batteries connected in series to give a steady voltage of 48V were connected to the 7.5KVAinverter of which also had the solar panels connected to it. These connections made up Unit A while the other two framework which had the four(4) old 12V batteries connected in series each (making up 8 batteries) were connected together in parallel to make up for the steady 48V and then connected to the 3.5KVA inverter which was connected to a 48V, 50A charge controller on which the solar panels were connected to. These connections made up Unit B. Unit A was made to supply the departmental offices and the lecturer offices which carries more load while Unit B was made to supply the 400level, 500level class and other few minor devices which had less load. The integration of both Units and the separation of loads led to a more efficient and reliable PV system for the department of Mechanical engineering as the alternate source of power can now be used for longer hours without powering down.