Arid Zone Journal of Engineering, Technology and Environment (AZOJETE)
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Design Analysis of Microcontroler Based Automatic Power Management in Photovoltaic Systems
Get PDFThis work considered the design analysis of an energy management system to control the state of battery discharge of a solar power system without any form of load discrimination, thus preventing a sudden system shut down. The state of discharge of the storage battery is monitored by the voltage level sensor. In particular, four voltage levels were used in this work namely: 11.5V (for less critical), 11.0V, 10.5V and 10.0V (for most critical load). The outputs of the sensors are then connected to a microcontroller which is programmed to isolate the loads in the order of priority. Tests result showed that at different voltage levels, specific load was disconnected from the desired voltage thus, stored energy was efficiently conserved. Accordingly, this prototype design ensures efficient energy management in photovoltaic systems
Performance Improvement of an Indirect Solar Dryer with Single Axis Manual Tracking System and Angular Simulation of the Flat Plate Collector Reflectors
Get PDFThe need of food preservation cannot be over-emphasised. Crops need to be processed and preserved in times of their abundance to ensure for life and specie sustainability in times of scarcity. Flat plate collectors (FPCs) are often made fixed and the positions of reflectors used on them are not normally specified; in this paper, a report of an experimental test of an indirect solar dryer whose FPC is operated manually in a single axis to track the sun is presented. To avoid incurring extra cost on the existing design, the FPC was rather made to be operated manually instead of the automation process. Using the Engineering Equation Solver (EES) and the TRNSYS 16 softwares, the angular positions of reflectors placed east and west on the FPC were simulated for the first quarter months of the year of the experiment – this included the month of the test. This is to ascertain the best positions for the reflectors in other to achieve maximum insolation. For the month of the test, March, the angular positions of the reflectors placed east and west of the FPC were found to be 40° and 80° respectively relative to the horizontal plane. The performance of the solar dryer in terms of the percentage moisture loss, drying rate, collector efficiency and drying efficiency was evaluated when the FPC was fixed and when it was made to track the sun and the results obtained there from were compared. In comparison, it was found that the dryer tested by manually tracking the sun increased the total percentage moisture loss by 5.11%; the total drying rate by 2.10×10-5 kg/s; the average collector efficiency by 3.92% and the overall drying efficiency by 2.0% as compare to when the FPC was fixed, i.e. not tracking the sun. The indirect solar dryer with the ability to manually track the sun in a single axis using the meteorological conditions of Zaria, Nigeria was therefore found to have increased the performance of the system dryer as compare to when tracking of the sun was not done
Assessment of Calcium Carbide Waste and Calcined Clay as Stabilizer in Flexible Pavement Construction
Get PDFStabilization techniques have often been used globally to enhance properties of weak subgrade materials for flexible pavement construction. This study assessed the blend of calcium carbide waste (CCW) and calcined clay (CC) to serve as an effective stabilizer of Subgrade material (S) sourced from a section along Ota-Idiroko road. Subgrade material was initially modified with CCW in different percentage replacements by weight (0, 4, 8, 12, 16 and 20%) and the resulting blends were subjected to Atterberg’s limits test to determine the blend with optimum plasticity index reduction which would be tagged optimum subgrade lime blend (OSLB). The blend of S + 8% CCW was tagged OSLB because it exhibited optimum plasticity index reduction. The OSLB was thereafter blended by weight with CC in the following percentage replacements 3, 6, 9, 12, 15 and 18% in order to activate the pozzolanic potentials of CC for strength enhancement. The resulting blends were subjected to Atterberg’s limits, Compaction, California bearing ratio (CBR) and Unconfined compressive strength (UCS) tests with the strength specimens cured for 0, 3, 7, 28, 56 and 90 days. The results showed that OSLB-CC blends reduced the Plasticity index from14.8 to 8.4 %, Maximum dry density from 1.82 to 1.54 Mg/m3, Optimum moisture content, 23.7 to 17.9 % and increased soaked CBR, 0 to 418.2% and UCS, 201.59 to 5660.84 kPa of natural subgrade respectively. Furthermore, the blends showed great improvement with reduction in PI less than standard value of 10% and increment in standard CBR and UCS values of 180% and 1700 kPa respectively for base course material. Therefore, stabilized blends at 7 days curing period could improve the natural subgrade to subbase and base for pavement construction
The Challenges and Panaceas to Power Distribution Losses in Nigeria
Get PDFEnergy losses in the distribution network and its subsystems have been issues of great concerns in Nigeria’s power sector. For decades, several studies have been conducted on the challenges facing the power sector in Nigeria with most focus directed on the distribution subsystems. The major challenge in the distribution system is the high energy losses which are detrimental to the techno-economic benefits of the power systems. However, details of the distribution system challenges and the probable solutions have not been efficiently presented. In this study, some of these challenges are presented and the potential solutions are proposed. The features of the Nigeria distribution network, the technical and non-technical sources of losses as well as the identified challenges are presented before discussing the potential solutions. The panaceas so provided were from the understanding of some published works and other related materials as well as the in-depth understanding of the authors. This article can serve as a guide for the utilities and stakeholders in the power sector for efficient management operations and improved customer service delivery
Modification of Thermal Hydraulic Transient Models for the Miniature Neutron Source Reactor
Get PDFA modified Miniature Neutron Source Reactor (MNSR) model dealing with transient thermal hydraulic problem is presented. The model based on lumped parameter method is adopted in this work to numerically solve a system of coupled algebraic and differential equations governing heat transfer in MNSR, using MATLAB solver for variable order method in stiff differential equations and Differential-Algebraic equations, coupled with Maple soft. The simulated results obtained from the model were generally in agreement when compared with reactor operation data recorded from 0 to 270 minutes during experiments. Radiating energy of Fuel and clad and heat transferred at the gap or clearance were taken in to account. Fuel and clad temperatures as well as various temperatures at different sections of the reactor were predicted with the model, in addition to the effect of the installed chiller on the reactor coolant
Evaluating the Potential of Microorganisms in Bioremediation of Lead Polluted Soil
Get PDFThis study evaluated and compared the abilities of indigenous Bacillus sp. and Micrococcus sp. for treating lead polluted soil. The organisms were inoculated into the contaminated soil samples prepared with the optimum values of screened determinant factors and experimented on 8, 16, 24, 32, 40, 48, and 56 days respectively for lead ion residual concentration using Atomic Absorption Spectrophotometer. Bacillus sp. showed greater remediation strength than Micrococcus sp. The results show that Bacillus sp. attenuated the Pb initial concentration from 150.74 mg/kg to control level in 40 days while Micrococcus sp. achieved that in 48 days. The 56th day residual concentrations and removal efficiencies were 81.43 mg/kg and 46% for Bacillus sp., and 86.91 mg/kg and 42.34% for Micrococcus sp. The removal rate was higher for Bacillus sp. (-0.0715 d-1) than for Micrococcus sp. (-0.0744d-1); and the remediation process was transport controlled. This information will be useful for remediation programs; and it will serve as a reference material for future research
Corrosion inhibition of mild steel determined using blended bitter leaf (Vernonnia amygdalina) extract and honey in dilute H2SO4 and HCl acid solutions
Get PDFThe inhibitive effect of bitter leaf extract (Veronia amygdalina) and honey hybrid on the corrosion of mild steel in dilute H2SO4 and HCl solutions was investigated using weight loss method. Various concentrations of the leaf extract and honey (5 to 25ml), and immersion times (96 to 240hrs) were recorded at room temperature (32°C), which were used to calculate the corrosion rates and inhibition effects. Inhibition was found to increase with increase in the inhibitor concentration. The inhibitive effect of honey as inhibitor on the corrosion of mild steel in dilute hydrochloric acid (HCl) solution with 54% efficiency and dilute H2SO4 acid solution with 48.03% inhibition efficiency were not as effective as that of hybrid with 72.48% inhibition efficiency. The results obtained indicated that both bitter leaf extract and honey could serve as an effective inhibitor for the corrosion of mild steel in dilute H2SO4 acid and dilute HCl solution
Mechanical and Structural Responses of Low Carbon Steel to Cold Rolling and Stress Relief Anneal Treatments
Get PDFThis study investigated the effect of deformation by cold rolling and stress relief anneal on the mechanical and structural properties of low carbon steel. The as-received steel samples were cold rolled at 20% – 40 % degrees of deformation using Buhler rolling machine in Metallurgical and Materials engineering department University of Lagos, Nigeria. Additionally, some of the cold rolled samples were annealed at a temperature of 650° C and soaked for 1 hour in a muffle furnace. The results revealed that the ultimate tensile strength (UTS), percent elongation, hardness and impact strength of the cold rolled low carbon steel improved significantly after stress relief anneal due to the elimination of induced strain hardening caused by cold rolling. The micrographs show that cold rolled + stress relief anneal caused significant recrystallization of ferrite-austenite phase to refine martensite with reduction of dislocations. Therefore, the low carbon steel can be used effectively for structural purposes in machines and equipment
Real-Time Detection of Abandoned Object using Centroid Difference Method
Get PDFAn abandoned object is one that remains stationary for an extended period. Such object might contain explosives and if left on purpose could cause death and injuries to people especially in crowded places. Abandoned objects need to be detected on time to prevent what might endanger people’s lives and health. Various methods have been developed to detect abandoned objects. The most reliable one is the vision-based method which automatically detects the abandoned object using image processing. The efficiency of the method was tested and evaluated on the customized datasets as well as the i-Lids advanced video surveillance system database. The Self -organizing Background Subtraction (SOBS) method overrides other methods in terms of its detection accuracy and simplicity of implementation, but fails for dynamic background scenarios. This work presents a real time vision-based object detection method using the centroid difference to improve on the accuracy of the detection and to tackle challenges of dynamic background of the SOBS method. Matlab Image processing toolbox was used to achieve this goal. The strategy is basically decomposed into two; foreground detection and stationary foreground object (SFO) detection. Gaussian Mixture Model is used for detecting the presence of newly introduced object into a scene (foreground detection), while the blob tracking approach based on frame counting is used to determine whether the detected foreground object is static/ abandoned or not. The results show that the detection accuracy of 83% was obtained which outperform the SOBS method with 67% accuracy. Future research should focus on tracking the person that abandoned the object for onward prosecution
Kinetics of Anaerobic Co-Digestion of Paunch Manure and Sugarcane Peels using Cow Dung as Inoculum
Get PDFAnaerobic co-digestion offers a prospective medium for transforming organic solid wastes into fuel, thereby providing an extra source of energy. This study investigates the kinetics of anaerobic co-digestion of paunch manure and sugarcane peels using cow dung as inoculum for biogas production. Anaerobic assay setup was in 3 digesters of 4 replicates with a total of 12 replicate batch digesters under mesophilic temperature range (30-35°C) for a retention time of 30 days. Cumulative biogas production for all digesters were measured and fitted to some selected models. The modified Gompertz equation was tested for its fitness. The kinetic parameters viz., biogas yield potential (P), maximum biogas production rate (Rm) and the duration of lag phase (λ) were recorded for each case as the digester with 0g sugarcane peels (control) produced maximum biogas of (83.14 (mL/g VS)) and the kinetic parameters P, Rm and λ were 89.0018 ml (g VS-1), 4.7089 ml (g VS d)-1, 0.8734 days respectively. It was observed that biogas production potential was inversely proportional to the substrate concentration of sugarcane peels in the digesters, the highest concentration of sugarcane peels (1.8g SP) recorded the lowest quantity of biogas with 37.9075 mL/g VS, 1.4547 g VS-1, 1.0891 days. Therefore, sugarcane peels should be co-digested with other substrates. The experimental kinetic data in-line with the Gompertz Model, Modified Gompertz Model Equation