Mechanical Engineering

The absence of slurry agitation mechanism in some conventional biodigesters has led to the malfunctioning of a given number of biogas plants installed for biogas production. Inadequate or lack of mixing of slurry in biodigesters limits gas production and renders the biogas plant economically unfeasible. This paper presents a detailed and novel approach for the construction and operation of a simple biogas plant that can be used in farms, homes, schools, etc for the production of biogas and organic fertilizer. A version of Floating Drum Biogas Digester is considered and a small tool referred to as agitator stick was introduced to help for a periodic agitation of the slurry in the digester. For its operation, the creation of an anaerobic environment in the digester is advised. This will help for the enhancement of the activities of anaerobic bacteria acting on the organic waste. The expulsion of air from the biogas holder while the digester is being loaded at the initial phase is also recommended for safety reasons. .

Nigeria as a developing country is witnessing population growth and rapid urbanization. Consequently, the demand for electric power supply and other infrastructures to support the growth is on the increase. In response, many thermal power plants (TPP) that run on liquid and gaseous fossil fuels are widely used in the country. However, the effects of the emissions from these power plants on human health and the environment have become matters of serious concern. High concentrations of various air pollutants have been reported across the country, and evidences of air pollution related morbidities abound. This paper presents the major types of Air pollutants and Greenhouse gases emitted by these units and their adverse impacts on the environment and health of the citizenry. Abatement techniques for some of the major emissions are also highlighted. The monitoring of the level of emissions and their control systems at these thermal power plants is strongly suggested so as to ensure their strict compliance to appropriate Ambient Air Quality Standards. There is urgent need to put in place legislations to enforce air quality standards in Nigeria as well as reduce the indiscriminate use of diesel and petrol generators through adequate public power supply. These will guarantee the health of the citizenry and the safety of the environment.

This paper presents the energy parameters of corn drying in a convective crop dryer powered by exhaust gas waste heat. The empirical study was applied for drying 1,500 g batch size of an indigenous variety of maize grains (corn kernels). The study considered the impact of the drying air temperature and velocity on the energy indices (total and specific energy consumption, electric and thermal energy demand), drying rate, of the crop dryer, and the moisture diffusion coefficient of the studied samples. Tests were run at varying drying air temperatures (50, 55, and 60 °C) and air velocities (1.0, 1.5, and 2.0 m/s). Results obtained show that the drying parameters had a noticeable influence on the rates of heat transfer and moisture diffusion in the maize samples. The average drying rates varied between 0.83 and 1.4 g/min, whereas drying duration ranged from 305 to 515 min. The thermal efficiency of the drying process ranged from 4.23% to 8.07%. Its values had a direct relationship with the drying air temperature and an inverse relationship with the drying air velocity. The specific energy consumption, which varied between 129.95 and 227.63 kWh/kg increased with increasing air temperature and velocity. Drying air temperature had an inverse effect on the values of the electric energy consumption of the dryer system at constant air velocity. The maximum and minimum thermal energy values were obtained as 97.12 and 55.4 kWhr, respectively. The activation energy and moisture diffusion coefficient values were in the range of 31.75 to 41.05 kJ/mol and 5.77 ×10 − 11 to 1.11 ×10 − 10 m 2 /s, respectively for the studied drying conditions. Prospects for commercial applications as well as recommendations for additional studies were stated.

Evaluation of the energy consumption during the thin-layer drying of yam slices in an exhaust gas waste heat recovery dryer is presented. The study took cognizance of some energy parameters such as the electric power consumption, thermal energy consumption and specific energy consumption during the drying process. Blanched white yam samples of different thicknesses were subjected to varying conditions of drying air temperatures and velocities of 55, 65, and 75°C; and 1.0, 1.5, and 2.0 m/s. The minimum value of electric power consumption (44.63 W-hr) was achieved at the drying air temperature and velocity of 75 ℃ and 1.0 m/s, and slice thickness of 1.0 cm; whereas a maximum value of 157.70 W-hr was obtained at the drying air temperature and velocity of 55 ℃, 2.0 m/s, and 1.0 cm slice thickness, respectively. The specific energy consumption values were in the range of 40.25 to 97.80, 52.33 to 108.79 and 58.77 to 124.16 kW-hr/kg, respectively for 1.0, 1.5 and 2.0 cm slice thicknesses. The results obtained revealed that the drying air temperature and velocity had an appreciable influence on the values of the energy consumption parameters of the dryer for the yam slice drying. It was observed that for all the experimental treatments, the higher the slice thickness of the yam samples, the higher the obtained energy consumption values.

This paper represents the Performance operating characteristics of single cylinder diesel engine using blend of chicken fat based Biodiesel at various loading conditions at constant speed. We compare the performance characteristics and smoke intensity of petroleum diesel with various blends of chicken fat based biodiesel with petroleum diesel.

The activities of industries such as those of bleaching, mining, printing, electroplating and metallurgical industries, textile and dye producing industries are among the major industries that have a problem of water contamination [1]. Unlike the biological or organic pollutants which are biodegradable , heavy metals like Nickel (Ni) and Chromium (Cr) are non-biodegradable [2]. This makes them a source of great concern. Heavy metals accumulate in living organism to a level that causes toxicological effect. Human health and the entire ecosystem are at great risk, unless the water and land systems are effectively managed. For example, the dye industry is one of the known largest industries that consume water. And the effluent coming out of the dye industries is known to contain various metallic compounds, chemical compounds and colouring compounds, which require adequate treatment before discharge into any available water body [3]. However, dye-laden effluents are very difficult to treat to a satisfactory extent because they are highly varying in composition, unlike other industrial wastewaters that can be treated easily because they are just contaminated in some ways, by either anthropogenic, industrial or commercial activities prior to their release into the environment, or its reuse [4]. Though most industries produce some form of wet wastes, the recent trends in developed technologies would be either to minimize such production, or recycle the waste within the production process. However, many of the ABSTRACT: Watermelon seed chaff was used to treat industrial wastewater from a paint industry. The packed bed filtration method was adopted, as the effect of the bed height, together with the adsorbent particle size were monitored. Adsorbent particle sizes of 1.18mm, 0.60mm and 0.125mm were used to pack the glass column at varying heights of 4cm, 6cm, 8cm and 10cm, while 100mls of the wastewater was filtered through the packed bed for each of the twelve cases. The time taken for the filtration, the volume of the treated water recovered, and the volumetric flow rates were all recorded. In the end, the analysis of the water quality test parameters show that the filtration through the smallest adsorbent particle size of 0.125mm packed to the highest height of 10cm had the greatest effect on the wastewater purification by bringing most of the test parameters closer to the permissible limits; giving pH value of 7.00 which is within the Federal Environmental Protection Agency (FEPA) permissible limit of 6.9; Temperature value of 25.3 0 C within the limit of 20-30 0 C; Turbidity result of 201NTU as against the FEPA limit of 250NTU; Conductivity value of 52µs/cm against the specified value of 200µs/cm; TDS and TSS values of 33.8mg/L and 200mg/L against the specified limits of 50mg/L and 250mg/L respectively; and Calcium, Iron and Zinc values of 0.40ppm, 0.07ppm and 23.07ppm which are all within the specified limits of 0.75ppm, 0.3ppm and 50ppm respectively. It is inferred that filtration of wastewater through a packed bed of watermelon seed chaff is a good method of wastewater purification and can be adopted on an industrial scale.

The fracture resistance of food grains is an essential piece of information required for the optimum design and development of agricultural post-harvest machinery. In this study, the strength properties of two varieties of Bambara kernels (TVSU-1395 and TVSU-1353) were examined in terms of the mean rupture force, absorbed energy, and deformation as affected by the moisture content and kernel size. To achieve this, a quasi-compressive force was applied on the two varieties of Bambara kernels of varying moisture contents (5.43%, 7.24%, 9.01%, 11.54%, and 13.62% wb) and kernel sizes (small, medium, and large) in between the loading compartments of a universal Testometric device at a 20 mm/min loading rate. The experiments take ten treatments with 20 replications subjected factorially to a completely randomised design (CRD) into consideration. The results revealed that the force needed to initiate the kernel fracture increased with an increase in the kernel size and moisture content fro...

The demand for freshwater has continued to soar amidst an increasing population, industrialization, and environmental pollution. The continuous shrinkage of this important resource has necessitated the need for a concerted effort on seawater desalination. Solar-powered desalination occupies a strategic position in the water-energy nexus and offers an alternative to taking off pressure from the already stressed freshwater sources. A numerical study with experimental validation of a single-slope double-effect solar still integrated with paraffin wax is thus presented. A transient mathematical model considering the humid air media in the upper and lower chambers was developed. Previous works in this area ignored the thermal analysis of the humid air medium, and as such, adopted the evaporation theory in the estimation of the freshwater yield. However, this study considers the thermal resistance offered by the humid air in the computation of the yield using the condensation theory. The energy-balance equations were discretized using the finite element method and solved with the aid of version 7.12 of the FlexPDE numerical solver. The model was validated with data from the experimental study. The correlation coefficients between the predicted and experimental data showed good agreement with values in the range of 0. 97 ≤ ≤ 0. 99 , and values of root mean square percent deviation of 3. 2% ≤ ≤ 16. 8%. The system achieved its best performance in November with a daily yield of 4.06 kg/m 2 and a mean efficiency of 33.7%. The upper basin contributed an average of 52% of the total yield with a greater percentage of its yield occurring during the nocturnal phase. The effects of the upper basin and the PCM on the diurnal performance of the system were evaluated.

This paper presents an analysis in the variation of sampling time of a synchronous motor drive that is self-controlled. The benefits of the synchronous motors are replacing classical induction and direct current (DC) motor drives. It is anticipated that they may be more significant in the imminent future. Because permanent magnet synchronous motors drives are preferred to perform vital tasks in most applications such as in the automotive industry and aerospace, the system reliability is usually an important consideration. Owing to these reasons, the sampling time of the drives have to be taken into consideration regarding how strong the impact of variation in sampling time can affect the drive performance. The drive is fed with three phase power and is utilized in speed regulation. Proportional integral (PI) regulatory approach is studied and is implemented in a PI-based speed regulatory system is presented. Simulation results of the motor current speed, and torque signals from the synchronous machine dynamics of the field flux are given. It was shown that an increase in sampling time results in the elimination of high frequency signal components.

The Design Analysis of a Pneumatic Vehicle aims to investigate and evaluate the performance and efficiency of a three-wheeled vehicle powered by pneumatic technology. The vehicle utilizes two cylinder tanks for air storage and employs a pneumatic cylinder with specific dimensions of 50mm bore, 20mm rod, and 138mm stroke. The primary objective of this project is to comprehensively analyse the design aspects of the pneumatic vehicle and assess its potential applications and benefits. This research involves a detailed examination of the vehicle's overall design, including its structural components, pneumatic system, and power transmission mechanisms. The performance of the vehicle, such as speed, acceleration, and manoeuvrability is assessed through practical experiments. It is being constructed with light material, simple way of working, low manufacturing and maintenance cost, it does not produce exhaust emission. The outcome contributes valuable insights into the potential applications of pneumatic vehicles, particularly those with three-wheel configurations. By evaluating the design and performance of the vehicle, the research shed light on the feasibility and advantages of adopting pneumatic technology in transportation systems. The research findings also provide useful guidelines for further improvements and optimization of the pneumatic vehicle design. Review of the availability and the impact of the fossil fuels and the cost increment in the present and future generation led us to construct a vehicle, which runs on air, as a renewable energy source. This report is a detailed description of the design, construction, working and testing of the pneumatic vehicle. In this report, operating pressure of 0.5Mpa is used, force produced by cylinder is 1864.6N, vehicle torque 93.23N-m and efficiency of the vehicle is 78%. This research also aims to explore potential applications of the pneumatic vehicle in various domains,

This paper presents an analysis in the variation of sampling time of a synchronous motor drive that is self-controlled. The benefits of the synchronous motors are replacing classical induction and direct current (DC) motor drives. It is anticipated that they may be more significant in the imminent future. Because permanent magnet synchronous motors drives are preferred to perform vital tasks in most applications such as in the automotive industry and aerospace, the system reliability is usually an important consideration. Owing to these reasons, the sampling time of the drives have to be taken into consideration regarding how strong the impact of variation in sampling time can affect the drive performance. The drive is fed with three phase power and is utilized in speed regulation. Proportional integral (PI) regulatory approach is studied and is implemented in a PI-based speed regulatory system is presented. Simulation results of the motor current speed, and torque signals from the ...

This paper presents an analysis in the variation of sampling time of a synchronous motor drive that is self-controlled. The benefits of the synchronous motors are replacing classical induction and direct current (DC) motor drives. It is anticipated that they may be more significant in the imminent future. Because permanent magnet synchronous motors drives are preferred to perform vital tasks in most applications such as in the automotive industry and aerospace, the system reliability is usually an important consideration. Owing to these reasons, the sampling time of the drives have to be taken into consideration regarding how strong the impact of variation in sampling time can affect the drive performance. The drive is fed with three phase power and is utilized in speed regulation. Proportional integral (PI) regulatory approach is studied and is implemented in a PI-based speed regulatory system is presented. Simulation results of the motor current speed, and torque signals from the ...

Extraction of virgin coconut oil from coconut kernel is a major influential step for their commercialization. There are many extraction processes among which cold and hot extraction are conventional extraction processes. This paper focused on the design, construction and testing of a coconut extractor using fresh-dry process based on the low pressure oil extraction method production of virgin coconut oil to reduce the settling time of oil. Additionally, tests carried out on the machine were the oil quality test, yield comparison with conventional oil extractors and user experience. The drying motor of 1500hp was used for grinding and a 12V Dc motor converted to an AC drive was used for conveying to the extraction chamber. A heating element of 3KW was incorporated in the extraction chamber which was properly lagged to avoid heat losses. Results obtained showed that it takes 800 seconds of heating time at 70 o C to actually extract oil from dried coconut under different parameter such as drying temperature, extraction time and moisture content. The production efficiency of machine was calculated to 69.5% and the machine performance was certified good. Oil quality was recorded at 0.46% free fatty acid. The designed extractor yielded approximately 20.7% of oil against 14.1% as recorded from traditional methods. User experience was rated an average of 8.47 on a maximum scale of 10 with ratings obtained from experts (7.5) experienced users (8.7) and non-experienced users (9.2). The production machine is novel for easier, safer and more economical extraction of virgin coconut oil over the traditional and conventional methods.

The provision of energy infrastructure is essential for economic growth, social cohesion, and environmental sustainability. This paper served to evaluate the challenges associated with energy development and transition across the African continent and proffer opportunities for sustainable transition. Extensive use of documents, official data and statistics on different aspects of the African society was employed for this study. Exploratory documentary research materials, extant literature, publications, journals and articles on the current status of energy generation and delivery in Africa, the concept of renewable energy pathways, the need for energy transitions and the major strategies in place in Africa and around the world were important study areas for this work. Exploratory research method and systematic review approach were used to study the energy transition techniques, challenges and opportunities across Africa. Important research points were the concept of renewable energy pathways, the need for energy transitions, the major strategies in place in Africa and around the world to meet with the zero-carbon emission strategies of 2050, the future directions in energy provision—renewable energy development, economic diversification and energy-efficiency in Africa and the effects of energy transition on the social, political, economic and cultural spheres across Africa. Results obtained showed that energy transition in Africa is rapidly growing, though differently across the region, following huge investments made into the renewable energy sector, legislations and policies on the fossil fuel usage and carbon emission and introduction of better and more efficient systems. Nevertheless, the challenges reported in this studying plaguing the African energy transition come in five spheres: social, political, economic, technological and cultural. These challenges seem to be ancient, ubiquitous and multidimensional. Harnessing the opportunities in renewable energy will surely boost the economy of the different case study countries. A willing socio-political disposition towards renewable energy sources, increased investment plan for cleaner energy, reduced emphasis on fossil fuels and private-public sector collaboration will surely be giant steps to tapping into the numerous benefits of renewable energy sources. Energy transition in African countries can only be achieved under the auspices of a strong political will, social drive, cultural motivation and technological inclination towards a sustainable transition to cleaner renewable energy sources and less focus on fossil fuels.

The work involved the need to, in the interim, improve on the quality of electric supply in the country by compensating the existing 28 bus Nigerian network using Static Var Compensators. This is in contrast to the long term measures of increasing the power generation capacity and expanding our transmission and distribution networks. Electrical energy is a product and like any other product, should satisfy the proper quality requirements. Nigeria as a developing country needs quality electric supply to satisfy the social, economic and technical needs of the country. But the quality of electric supply generation to satisfy these needs leaves much to be desired. This paper examined the quality of electric supply in Nigeria and proffered modern methods to improve on the quality using FACTS devices.