The Nigerian Universities rely on weak and unreliable fossil-based electric grids with diesel engine generators (DEG) as a backup. However, there is a potential to light up the campuses using power systems derived from primary renewable power systems (RPS) like wind turbine (WT) and solar photovoltaic (PV), that can be on or off-grid to improve the energy mix and duration reliably. This study presents the comparative analysis of the optimal hybrid grid and off-grid systems (OGS & OOGS) for serving the demand load of university buildings in four climatic regions of Nigeria. HOMER Pro is used to design and select the systems based on minimal net present cost (NPC) and cost of electricity (COE). The impact of a minimal renewable fraction of 95% on the optimal system architecture (OSA) and COE is studied for both grid and off-grid modes. Also, sensitivity analysis of the impact of key variables on performance for the sites is carried out. It is found that the OGS in the four regions is PV/Converter (Conv), while for the OOGS, it is PV/WT/DEG/battery (BB)/Conv except in Port Harcourt (PH), where it is PV/DEG/BB/Conv. The COE for the OGS in the Savana and monsoon climes of Enugu and PH are 10 and 19% more than that in the warm-semi arid climate zones of Maiduguri and Kano, which is approximately 0.09 $/kWh. The COE ($/kWh) for the OOGS is 0.21 in Maiduguri, 0.245 in Kano, 0.275 in Enugu and 0.338 in PH. An obligatory 95% RF changes the architecture and increases COE in all the locations except Maiduguri, with a slightly improved COE but higher NPC like other locations. It is established that the suggested hybrid system is beneficial and feasible for supplying more reliable and clean energy to educational buildings in different Nigerian locations.
This research is focused on the propulsion of aircraft using electricity. More electric aircraft approach has allowed the older power subsystems to be replaced by electrical systems within modern aircraft. The result of the lift power requirement should be a boost for battery companies to develop FWA. The result of the current study inferred that the Flying Wing Aircraft is more aerodynamic and would improve aircraft efficiency and emit less emission.The gas turbine-based propulsion systems were responsible for the emission of pollutants that damage the ecosphere. Commercial aviation represented a large portion of carbon emissions within the aviation industry, so this study focused on novel aircraft propulsion systems for large commercial aircraft. Electric propulsion was considered to be an alternative to conventional propulsion systems. Therefore, this report analyzed the various electric aircraft concepts within the aerospace industry to see whether they have environmental benefits. A flying wing aircraft was compared to a conventional tube-and-wing aircraft using Computational Fluid Dynamics to determine which aircraft requires more power.The lift forces acting on the conventional aircraft and flying wing at cruise speed were 269,110 N and 10681 N, while the drag forces acting on the conventional aircraft and Flying Wing Aircraft at cruise speed were 260,940N and 7679N, respectively. More electric aircraft approach has allowed the older power subsystems to be replaced by electrical systems within modern aircrafts such as the Boeings, airbus, etc. This has increased fuel efficiency. The result of the lift power requirement should be a boost for battery companies to develop FWA. Conclusively, the result inferred that the Flying Wing Aircraft is more aerodynamic and, therefore, would improve aircraft efficiency and emit less emission.
Many researches had attempted characterization of biodiesel to determine its appropriateness as fuel for internal combustion engine. The paper aimed at evaluating the performance of vegetable –based waste cooking oil biodiesel as alternative diesel engine fuel. The methodology of the study was experimental. The waste oil was transesterified and chemical analyses performed to establish physico-chemical properties of diesel, ‘pure’ biodiesel and blends. The test fuels were evaluated for brake specific fuel consumption and brake thermal efficiency (ηth) at varying brake power on test rig consisting of Mazda engine coupled with a power take off propeller inserted in the power take off shape to Froude hydraulic dynamometer. The results were that at all brake power, the BSFC decreased as strength of diesel increased in the blend. At brake power of 15KW, BSFC (kg/KWh) for BD25, BD50, and BD75 were 0.41, 0.40 and 0.38 respectively while automobile gas oil and pure biodiesel recorded 21.5 and 23.8 in that order. The brake thermal efficiency had a contrary trend with BSFC. However, as the load increased, brake thermal efficiency (ηth) increased for all the test fuels utilized. In conclusion, biodiesel has demonstrated features of lean fuel, but exhibited high performance in IC engine. The technology could support agricultural value chain and boost socioeconomic development of Africa. Keywords: Biodiesel, Brake Fuel Consumption, Efficiency, Test Rig, Blends, Dynamometer
Studies on the effects of laser glazed and unglazed sample surfaces on the pitting corrosion resistance of nickel alloy 718 have been carried out. Both sample surfaces of nickel alloy 718 were cut to different dimensions for pitting corrosion tests using potentiostatic polarization process. The alloy samples used for electrochemical testing were connected to a flexible wire joined by spot weld process. The alloy samples were coated with low viscous polymeric wax leaving the surface areas to be tested exposed to seawater and one mole concentration of hydrochloric acid environments. These samples which are working electrodes have electrical connection between reference electrode and counter electrode and the entire system were connected to computer with PSTrace software that stands as potentiostat. Pre and post morphological examination of the sample surfaces were done using confocal laser scanning microscopy and scanning electron microscopy respectively. The results of pitting corrosion tests showed that the glazed and unglazed alloy sample surfaces immersed in seawater environment suffered from pitting corrosion as a result of the presence of pit initiation sites developed during surface laser treatment and also the presence of some aggressive anions like Cl -, SO 4 etc in the environment which migrated into the pits due to electrostatic balance and escalated pitting corrosion; while the samples of both surfaces immersed in 1MHCl suffered more from general corrosion. Post pitting corrosion examinations revealed that corrosion oxide films formed on the sample surfaces in acidic and alkaline environments were not protective as they flaked and exposed the sample surfaces to more corrosion attack.
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