Theses and Dissertation collection from the Faculty of Engineering and Technology


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Now showing 1 - 8 of 8
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    Nigeria is blessed with over 2.7 billion tonnes of coal and several hectares of forest reserves. However, millions of tonnes of coal slack and wood residues (biomass) generated from coal mining and wood processing respectively, are often discarded as wastes because of near absence of processing. These wastes have enormous potentials as energy sources for both domestic and industrial applications if well processed. Therefore, the aim of this study was to develop and characterise Hybrid Fuel Briquettes (HFB) from lean grade coal fines and torrefied woody biomass using pitch, molasses and starch as binders. The objectives were to: (i) characterise coal fines and woody biomass from Teak (Tectona grandis) and Melina (Gmelina aborea); (ii) optimise and determine the effect of torrefaction conditions on the combustion properties of the woody biomass; (iii) produce HFB from coal fines and torrefied woody biomass; and (iv) evaluate the mechanical and combustion properties of the HFB. Teak and Melina woody biomass from Benin, Edo state, and coal from Okaba mine, Kogi state were used in this study. Thermal decomposition studies were carried out on the woody biomass and Okaba coal fines in a STA7300 Thermobalance system. Each of the woody biomass samples of particle sizes 2 and 6 mm, were torrefied at temperature of 240 and 300 , for 30 and 60 min residence time and then characterised for their combustion properties. The HFB were produced from the coal fines and torrefied biomass aggregates using the organic binders in a hydraulic press at 14-55 MPa. The briquettes were cured in an inert environment at 200-300 for 60-120 min. Mechanical and combustion properties of the HFB were evaluated to determine its strength and energy contents, respectively. Phase identification and chemical composition were determined using Fourier Transform Infrared Spectrophotometry, X-ray Diffractometry and X-ray Fluorescence spectrometry. Microstructural and elemental studies were also carried out using Scanning Electron Microscopy and Electron Probe Microanalysis. The findings of the study were that: (i) the woody biomass (Teak and Melina) had Fixed carbon (FC), Volatile Matter (VM), ash, Higher Heating Value (HHV) in the range of 8.92 - 11.73%, 79.26 - 81.42%, 1.73 - 2.15%, 18.39 - 18.72 MJ/kg, respectively, while coal had 66.92% FC, 13.77% VM and HHV of 23.13 MJ/kg; (ii) optimised torrefaction conditions of the woody biomass were: particle size, 2 mm; temperature, 260 ; and residence time, 60 min, which resulted in higher FC (41-42%), lower VM (54%) and greater HHV (23 MJ/kg); (iii) the best formulation ratio for the HFB (coal and torrefied biomass) production was 97:3 using blend of 8% pitch and 7% molasses under 28 MPa compared with other formulations; and (iv) mechanical strength such as drop to fracture (200 times/2m) and cold crushing strength (11 MPa) as well as energy content (24 MJ/kg) of the HFB were higher compared with standards. The study concluded that the HFB developed has sufficient mechanical strength with desirable combustion properties and thus can be used for energy generation. Therefore, this HFB is recommended for domestic and industrial applications.
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    Reliability Assessment of the flexural Behavior of Reinforced Concrete Beam with embedded PVC Pipes
    Beams are major structural elements in structures against flexural failure. Increasing the span of building, increases the risk of deflection leading to increase in structural member thickness. Structural elements failures, due to the presence of electrical wire installation, are minimized by conducting them through the hollow polyvinyl chloride (PVC) pipes. In the tensile zone below the neutral axis, some concrete and reinforcing steel are eliminated by the presence of PVC pipes; hence, paving way for effective materials utilization. Therefore, the aim of this study was to investigate the reliability of the flexural strength of reinforced concrete beam with embedded PVC pipes below the neutral axis by experiment and modelling using ANSYS Pro 15.0. The objectives were to: (i) determine the compressive strength of concrete cubes with and without embedded PVC pipes and their stress-strain relationship; (ii) investigate the flexural behaviour of the beams with and without PVC pipes and their relationship with compressive strength; and (iii) evaluate the reliability of the beam with and without PVC pipes using the First Order Reliability Method (FORM). Finite Element Method (FEM) was used and adopted for designing and modelling the beams (1000 x 150 x 150 mm) using a FORTRAN subroutine created and linked with the reliability software (FORM5). Experimental tests were carried out on conventional reinforced concrete beams with and without PVC pipes (diameter; 50 mm, density; 1.41g/cm3, thickness; 3 mm) below the neutral axis. Flexural strength tests were carried out using ASTM C 293 standard method. Stress, modulus of elasticity, peak and ultimate strain were measured and an improved analytical model was developed for the study of the flexural behaviour of reinforced concrete beams with and without PVC pipes using BioStat Pro and MS-Excel respectively. Finite Element Analysis and validation of experimental results of flexural strength were carried out using ANSYS Pro 15.0. The findings of the study were that: (i) average compressive strength of all the non-embedded PVC concrete increased with curing age and ranges between 2-14% higher than specimen with embedded PVC pipes; (ii) flexural modulus of rupture (MoR) for beams without embedded PVC pipes were higher than PVC beams by 2.9% with similar failure pattern; (iii) proposed models using regression analysis at 5% level of significance for all beam specimens were in close agreement (within the range of 98%) with experimental data; (iv) finite element modeling and simulation show close agreement (within the range of 96%) with experimental results for all the specimens when subjected to the same test conditions; and (v) reliability analysis using the first order reliability method (FORM) for PVC beams revealed a safety index, within the range (3.7 ≤ β ≤ 4.7) specified by ASTM C 293 with volume reduction between 6.1-9.9% compared to the non-embedded PVC beams. The study concluded that beams with embedded PVC pipes below the neutral axis are economical and reliable. Therefore, it is recommended for same application with the conventional beam since their capacities recorded by experiment are in agreement with theoretical and simulation values.
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    (UNIVERSITY OF ILORIN, 2018-01) AWOLOLA, Olalekan Obadele
    The global increase in ambient temperature is partly responsible for increase in energy consumption of cooling systems. Therefore, there is a need to optimise systems designs which require design codes based on current meteorological data. The aim of this study was to develop models from weather data that will provide useful information for developing new design codes for air-conditioning and refrigeration systems in Nigeria.The objectives were to: (i) evaluate the 1%, 2½% and 5% design conditions for dry bulb temperature (TDB) and the coincident relative humidity (CRH) of the four warmest months (FWMs); (ii) develop the probability density function (PDF) and cumulative distribution functions (CDF) by evaluating TDB and relative humidity (RH) bins and develop models for degree-days; (iii) evaluate the two-dimensional (2D) bin of TDB and RH to establish number of hours per year in the comfort zone per location; and (iv) investigate the effect of TDB on the energy consumption of refrigerators and air-conditioners. From the hourly data of eighteen stations of Nigerian Meteorological Services Agency, outdoor 1%, 2½%, and 5% design conditions for TDB of FWMs were determined using Gaussian distribution table with their corresponding CRH. Thereafter 0.4%, 1.0% and 2.0% upper percentiles were determined from the CDF curves and the CRH was obtained for the percentiles per location. Models were developed by averaging PDFs and CDFs of TDB. The degree-days models were obtained from CDF models. The numbers of hours that TDB and RH pairs are within the comfort zones and appreciable evaporative cooling can be experienced were estimated per location from 2D bin data. The accuracy of the models waschecked using Mean Forecasting Error (MFE), Mean Absolute Deviation (MAD) and Mean Absolute Percentage Error (MAPE). The effect of TDB on energy consumption was investigated in four ambient temperature conditions for refrigeration systems, and 15days for air conditioning systems. Results showed that the: (i) 2½% design conditions for human comfort for TDB were42.7°C for Maiduguri and 32.6°C for Jos being the maximum and minimum,with their corresponding CRH of 14.7% and 17.4% respectively; (ii) maximum errors obtained for CDF were 0.04, 0.03 and 4.14% for MAD, MFE and MAPE respectively and annual degree-days were below 10% for MAPE for most of the base temperatures when the results from modelsand the weather data were compared; (iii) highest hours of TDB and RH pair in the comfort and appreciable-evaporative-cooling zones occurred for Kano (2042 hours) and Sokoto (2400 hours) respectively; and (iv) highest energy consumed by refrigerators (rated 110 W) was 326.5Wh for 3hours at 37.1°C average TDBnear bakery-oven and for AC (of 3.52 - 3.57 kW cooling capacity) was 12.39kWh at 26.5°C outside and 22.0°C inside TDB. The study concluded that the models and the new design codes were good in predicting energy consumption for refrigeration and air-conditioning systems.Hence, the outside design conditions computed are useful for revising the design code for comfort air conditioning system for various locations in Nigeria.
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    Energy requirement of tillage operations depends on soil properties, tool and operating parameters. Effects of these factors on energy requirement to reduce cost of production, during tillage operations are yet to be thoroughly investigated. This study was aimed at determining parameters affecting energy requirement during tillage. The objectives of the study were to: (i) determine the engineering properties of the soil; (ii) determine soil draught of an inclined narrow model chisel blades in the laboratory soil bin; and (iii) develop empirical model equations for predicting draught and validate them with experimental data. A modified soil bin measuring was used for the experiment. Soil samples collected from 36 representative locations in Kwara State were analyzed and mixed thoroughly before loading. Tool and soil processing carriages and model chisel blades were designed and constructed. The system was instrumented to log the draught in XYZ directions with respect to distance and time. Soil preparation for data collection involved soil pulverization, leveling and compaction. Soil penetration resistance and bulk density were determined at several locations along and across the soil bin. Effects of operating depth (20, 40, 60, 80, and 100 mm); forward speed (0.25, 0.50, 0.75, 1.00 and 1.25 m/s); tool cutting edge width (10, 20, 30, 40 and 50 mm); and tool angle of lift (20, 30, 40, 50 and 60°), on draught were studied. Soil moisture content range was maintained at 10 to 12% (dry basis) throughout the experiment. A 45 factorial statistical design in a completely randomized block was used. Regression equations were developed based on the contribution of each factor and combination of all factors to draught of tillage tool. The model equations developed were validated using parameters obtained from the soil bin experiment. The findings of the study were that: (i) engineering properties of the soil were 1.50 g/cm3, 26.6°, 29.8° and 16.67 kPa for bulk density, angle of internal friction, soil-metal friction angle and cohesion, respectively; (ii) draught of inclined narrow model chisel was affected by width of cutting edge, depth, operating speed and angle of lift. The effects of interactions of these parameters were also significant (p ≤ 0.05); and (iii) regression equations showed linear relationship between draught and speed (R² = 0.85), width of cutting edge (R² = 0.99), and depth of operation (R² = 0.91) while the relationship between draught and tool angle of lift was quadratic (R² = 0.94). The study concluded that tool width, lift angle, depth, speed of operation and soil type are parameters that affect energy requirement of an inclined narrow model chisel blade. It is therefore recommended that the effects of these parameters must be considered in the design of an inclined narrow model chisel blade to enhance effective tillage operations and minimize energy requirement.
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    Knowledge of energy in crop production is essential for enhancing food production for the rapidly increasing population. Adequate attention has not been given to the analysis of energy inputs in crop production in Nigeria. Consequently, it is difficultto determine viable energy inputs in the production processesand plan for conservation. Therefore, there is a need for evaluation of energy consumption in cassava production in Kwara State, Nigeria.The aim of this study was to determine energy requirement in cassava production in the State, and hence develop model equations for predicting yield under different farming practices. Thespecificobjectives of the study were to:i) investigate energy inputs and output per hectare in cassava production; ii) determine energy use efficiency in cassava production; iii) investigate the effects of energy inputs on cassava productivity; and iv) investigate the relationship between cassava yield and different energy input sources. Data from 175 farms were collected through site visits and physical measurements for 3 consecutive cropping seasons (2013 - 2016). The farms were classified into 3 groups based on size of farm and level of mechanization: small scale (1 to 5 ha), medium scale (6 to 15 ha) and large scale (16 to 50 ha). There were 92 farms in the small scale group while medium and large scale farms were 54 and 29 farms, respectively. Inputs used in cassava production (cassava setts, chemicals, diesel fuel, fertilizers, human labour and machinery) and output (cassava yield) were determined per hectare and then multiplied by the coefficient of energy equivalents. The data generated were statistically analyzed using R software. Cobb-Douglas production function and multiple linear regression analysis were applied to analyze the relationship between energy inputs and cassava yieldto develop yield predictive models. The findings of the study were that: i) cassava production consumed a total energy of 4904.87 MJ/ha, 36352.04 MJ/ha and 96 257.93MJ/ha while average energy output were 107,632 MJ/ha, 604,800 MJ/ha and 2,016, 000 MJ/ha, respectively in small, medium and large scale farms respectively; ii) energy use efficiency for cassava production was 16.13, 16.69 and 20.94% for small, medium and large scale farms, respectively; iii) average values of net energy used and energy productivity were respectively 100, 959 MJ/ha and 2.88 for small scale farms, 568, 560 MJ/ha and 2.98 for medium scale farms, and 1, 919, 742 MJ/ha and 3.74 for large scale farms; and iv) indirect and non- renewable energies had higher impacts on cassava yield than direct and renewable energies in medium and large-scale farms. Reverse was the case in small scale farms; The study concluded that input variables in cassava production are independent of each other. Three parametric models were developed in this study to predict cassava yield. Model I with the highest R2 value and no autocorrelation at 5% significance levelis recommended to scientists in order to boost cassava yield.Results of this study would be useful to cassava farmers in Kwara State and elsewhere with similar soil characteristics and operating conditions.
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    Modelling and Optimal Control of the Cascaded Kainji and Jebba Hydroelectric Power System in Nigeria
    (UNIVERSITY OF ILORIN, 2018-04) OGUNBIYI, Olalekan
    The cascaded hydroelectric power stations at Kainji and Jebba on the River Niger play a vital role in the Nigerian electricity supply that has been in a state of crisis for over four decades. Sustainable solutions to this problem require strategic solutions like the Roadmap for Power Sector Reform of 2010 and tactical components that address knotty issues of operations and management that have so far been either outsourced or completely omitted. The latter devolves into addressing the nearly intractable problem of determining control strategies that optimize suitable performance indices constrained by the dynamical equations describing the reservoirs. The aim of this research is to develop dynamical models and control strategies for optimal power generation at Kainji and Jebba hydroelectric power stations. The objectives were to: (i) develop a mathematical model (incorporating reservoir characteristics, inputs such as inflows with outflows due to power generation, flood-control discharges and evaporation); (ii) numerically solve the resulting equations and determine the parameters using measured data; and (iii) compute control laws for optimal operation of the system. A nonlinear dynamical model derived using energy conservation and flow continuity conditions was solved numerically employing an Adams-Moulton-Bashforth predictor-corrector integrator with a Runge-Kutta starter (AMBPCRKS). Reservoir parameters were then estimated using information obtained from a database created using National Control Centre (NCC) data and observations of evaporation and power generation during the study period. The optimal control problem, formulated as the minimisation of a quadratic cost functional subject to the system’s dynamical equations, was then solved by direct and indirect methods. The indirect method, which is based on Pontryagin’s Minimum Principle (PMP), resulted in a two-point boundary value problem (TPBVP) which was subsequently solved by an innovated multiple shooting technique referred to as the Progressive Domain Extension Method (PDEM) and a conjugate gradient algorithm. The findings from the study were that: i. integrating model equations using the AMBPCRKS in an EXCEL-VBA® environment achieved an accuracy of the fifth order; ii. the calibrated model using reservoir parameters with actual inflows and outflows were within 2% of observed values, thus making it a dependable tool for planning, operations and training; iii. approximate finite-dimensional optimal controls computed by the steepest descent and conjugate gradient approaches converged to nearly identical values although the latter technique took fewer iterations; and iv. PMP-based controls extracted through the TPBVP can be solved using PDEM and conjugate gradient approaches with a stop criterion of 10-6, with the results being almost identical and practically realisable. In conclusion, the research successfully addressed an extant frustrating difficulty confronting the operators of the cascaded power stations by solving an optimal control problem using available information and innovative computational methods realized on the ubiquitous EXCEL-VBA® platform. It is recommended that the ownership of the stations and government be encouraged to adopt the results for planning, operations, training of engineers and management as well as to support further work to complete the control process.
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    (UNIVERSITY OF ILORIN, 2019-12) OYELEKE, Joseph Kehinde
    Earthquake with its damaging occurrence along fault line causes failure of buildings. This could be reduced by introducing materials that can withstand seismicity as against large sections used in conventional frame building (CFB). Conventional method of anti-seismic technique increases the stiffness of structures by enlarging structural elements, which accommodates seismic load because of the added mass to structures, this increase the weight of building while the safety level is little improved. The aim of this study was to investigate Cold-formed steel Concrete (CSC) frame building with Strawbale infill panels (SIP) under seismic loadings. The objectives were to: (i) assess a 4 storey CSC frame symmetric building with strawbale infill panel; (ii) perform numerical modeling and analysis of theCSC frame building with SIP; (iii) determine the building response to seismic loadings; and (iv) compare the behaviour of CSC frame building model with SIP to the behaviour of CFB model with sandcrete block masonry infill panels. The 4 storey CSC frame building model with SIP was assessed by identifying capabilities of its material properties to resist seismic loading activities.The building geometry, location of soil conditions, location of building with respect to seismicity and ductility parameters and applied loads were considered in the modeling of the building.Numerical modeling of CSC frame building with SIP was done and subjected to seismic load using Response Spectrum Analysis (RSA) and 5 Time History (TH) data. Data obtained from Haiti earthquake of 2010 was used for the RSA in accordance withEurocode8, while the 5 TH data were obtained from Elcentro, Petrolia, Northridge, Lucerne and Slymarff earthquakes.ETABS 2016 software was employed for the modeling and analysis of the building and the results of both analyses were subjected to safety verification in accordance with Eurocode 8.A similar CFB was then modelled and compared to theCSC building with SIP. The findings of the study were that: (i) the CSC frame building with SIP offered 25.3% more of resistance to external forces; (ii) building model showed a total weight of 16067.11KN and modal analysis of first 6 modes ranged between 0.644 to 0.117 periods; xiv (iii) response of building model under RSA revealed that maximum displacement of 127.85mm occurred at the top of the building while the maximum drift of 0.016 occurred on the first storey. (iv) five THanalysis showed that the maximum displacement occurred at the top level for all five earthquake data used, with Petrolia earthquake data having the highest displacement value of 50.35 mm, and a maximum storey drift value of 0.0068; and (v) CSC frame building with SIP under seismic load has a storey drift of 0.0068 compared to CFB with drift value of 0.00912. The study concluded that the maximum displacement and drift of CSC frame building with strawbale infill panel under seismic load occurred at the top of the building. The study recommended that CSC building with SIP be incorporated in building standard, as this composition is more stable under earthquake than CFB.
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    Water is a renewable resource which should be preserved and protected. Untreated wastewater from aquaculture such as catfish farming most times end up in water bodies which could be sources of water supply downstream. Such water, if untreated before use or discharge into water bodies could result in eutrophication and human diseases. Untreated effluent from catfish farming can thus have these consequences. Therefore, there is a need to examine how the effluent from aquaculture can be treated before discharge. The aim of this study was to investigate the suitability of sawdust waste as a medium for aquaculture effluent treatment. The objectives of the study were to: (i). investigate current practice of Catfish Farming Effluent CFE disposal; (ii). assess quality of CFE; (iii). examine the adsorption abilities of sawdust, Activated Sawdust (AS), and Commercial Activated Carbon (CAC); and (iv). investigate the efficiency of AS in the treatment of CFE. The methodology employed involved treatment of CFE using adsorption via a batch process in the laboratory and conversion of two different types of sawdust: homogenous (Isoberlina doka wood specie) and heterogeneous mix (Daniella ogea, Anogesus olivera, Isoberlina doka, Afzelia bipinensis and Gmelina arborea). Wastewater was collected from different catfish farms within Ilorin, the study area. Sawdust was converted into AS using orthophosphoric acid as the activating agent based on a 3-factorial design. The factors considered were molarity of acid, temperature and activation period. Treatment of CFE was investigated using the following physicochemical parameters: Total Dissolved Solids (TDS), Biochemical Oxygen Demand (BOD), nitrite, nitrate and phosphorus. The CFE was also treated with CAC. The laboratory analysis was conducted using Standard Methods. The findings of the study were that: (i). CFE is currently discharged untreated through pipes from ponds into open drains; (ii). untreated effluent has TDS, BOD, nitrite, nitrate and phosphorus values of 520 mg/l, 17.4 mg/l, 0.42 mg/l, 150.45 mg/l and 2.48 mg/l, respectively while the discharge limits are 2000 mg/l; 6.0 mg/l; 0.08 mg/l; 40 mg/l; and 3.5 mg/l, respectively; (iii). after treatment with sawdust, AS and CAC, TDS reduced from 520 mg/l to 150 mg/l, 210 mg/l and 260 mg/l; BOD from 17.4 mg/l with no change with sawdust, 9.8 mg/l and 9.9 mg/l; nitrite from 0.42 mg/l to 0.32 mg/l, 0.07 mg/l and 0.31 mg/l; phosphorus from 2.48 mg/l to 2.2 mg/l, 2.12 mg/l and 2.19 mg/l. However, nitrate increased in value from 150.45 mg/l to 175.8 mg/l, 156.1 mg/l and 200 mg/l; and (iv). the efficiency of AS treatment for phosphorus, BOD, TDS and nitrite were 12 %, 44 %, 60 %, and 83 %, respectively. The study concluded that activated sawdust has the potential as an adsorbent for treatment of aquaculture wastewater which simultaneously solves the problem of indiscriminate sawdust disposal. The study recommended that AS should be adopted for the treatment of CFE prior to discharge into water bodies.