FACULTY OF TECHNOLOGY
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Item Multi-functional concrete with recycled aggregate(2023) Yidong X.U.; Ruoyu J.Item Use of Efficient and Affordable Technologies in Checkmating the Existence of Hazardous Waste(2010) Wahab A.A.; Issa F.O.; Dahiru B.; Ajagbe W.O.One of the major problems impeding achieving environmentally sound management of hazardous waste (domestic, agricultural or industrial) in African countries is that there are no efficient and affordable technologies that can be adhered to. Human activities, either for production or processing lead to the production of wastes (solid, liquid or gas) which must be minimized because of their harmful effect on health of the living being and their destruction of environmental aestheticism. The technologies like rotary kiln, chemical disinfection etc, are efficient but they have not yielded the needed result. The reason is that they are not affordable. The affordable ones like brick or drum incinerator, waste burning and others result to massive emission of black smoke, fly ash and repulsive odours. All these eventually have negative effects on climate. This paper aims at promoting efficient and affordable technologies to manage hazardous waste in Ibadan, Nigeria. It provides information on the locations, types and sources of hazardous waste generated in this area and use this information to choose appropriate technologies that are affordable by the people. It is recommended that waste recycling and reuse, safe bury, waste minimization, composting and landfill technologies should be encouraged. Government at all levels should work in hand with the NGOs, community-based organizations, women, youth and public interest group programmes, in collaboration with local municipal authorities, to mobilize community support for waste reuse and recycling through focused community-level campaigns. Also, these technologies should be publicized through workshops, local meetings, and mass media to the populace for the benefit of the community and the country as a whole.Item Pretreatment of recycle aggregates(2023) Olonade K.A.; Akindahunsi A.A.; Ajagbe W.O.; Adebanjo A.U.; Tijani M.AItem Multi-functional concrete with recycled aggregate(2022) Yidong X.U.|| Ruoyu J.Pervious Concrete (PC) pavement is one of the most prevalent Sustainable Urban Drainage Systems (SUDS) used to decrease the risk of flooding, allow the natural disposal of water through infiltration and reduce the pollution of watercourses. The use of agricultural waste and collapsed buildings rubbles are reported to improve the properties of conventional concrete. However, their use in PC has not been fully explored. This study was designed to investigate the effect of Sorghum Husk Ash (SHA) on the properties of Recycled Concrete Aggregates (RCA) PC. Sorghum husk was incinerated at 700°C for three hours to produce SHA. The chemical composition of SHA was determined using an X- ray fluorescence analyzer. Rubbles of collapsed buildings were crushed to smaller sizes for physical and mechanical tests [specific gravity, water absorption, bulk density, void ratio, aggregate crushing value (ACV), and aggregate impact value (AIV)] and sieved to between 9.50 and 4.75 mm for PC production. Mix proportioning was done following ACI specifications. Mixtures of PC were prepared at various replacement levels (0, 5, 10, 15, 20, and 25%) of cement with SHA using 100% RCA. These were molded into 100 mm (height) x 200 mm (diameter) cylindrical samples. The prepared samples’ density, compressive strength, porosity, and permeability was determined at 28-day of curing using ACI standards. The properties were correlated using regression equations in Microsoft Excel Software 2013. The adequacy of adopted equations was determined using the coefficient of determination (R2). The sum of percentages (77.3%) of silica, alumina, and ferric oxide was obtained for SHA, which is over 70% requirement of a pozzolan. Suitable result was obtained for physical and mechanical [specific gravity (2.53), water absorption (2.8%), bulk density (1301 kg/m3), void ratio (48.58%), ACV (26.96%), and AIV (24.02%)] properties of RCA. The density and compressive strength of RCA-PC respectively reduces from 1748 - 1715 kg/m3 and 7.78 - 4.05 N/mm2 while the porosity and permeability increase from 24.06 - 28.11% and 8.71 - 13.86 mm/s as the percentage replacement of SHA increases from 5 - 25%. The recorded compressive strength for all the mixtures was within the ACI acceptable specification (2-28 N/mm2). Increasing the contents of SHA significantly enhanced the porosity and permeability of PC, while the optimum compressive strength was obtained at 5%. The R2 of regression equations (0.90-0.99) indicates good correlations among the PC properties. It is concluded that SHA pozzolan and RCA are suitable for the production of PC for SUDS.Item Numerical investigation of forces and acceleration for air-sea unmanned aerial vehicle in transition(2023) Chukwuemeka, E. C.; Ames, F.; Kazeem, R. A.; Petinrin, M. O.; Ikumapayi, O. M.; Akinlabi, E. T.The air-sea UAV is made to be able to fly, change from land to water, and navigate through submerged water. However, as it moves from the air to the water, it experiences a significant impact force. The UAV’s structure and components run the risk of being harmed by this strong impact force. The accelerations and forces involved in the transition process must therefore be understood through quantitative research. The method was created using computational fluid dynamics (CFD), which can manage the process of water entry. The simulation and calculations were carried out using the Fluent software suite from ANSYS Inc. The research examined the UAV’s wing and center bodies independently and separately. 3-D models were used for the analyses of the center body, while 2-D models were used for the wing-body analyses. The transition flow and submerged methods were taken into consideration in obtaining the impact load that a body experiences when transitioning into water. Because it was substantiated using experimental results from prior studies, the transient-time analysis-based transition techniquewas shown to be reliable. The steady-state analysis of the submerged flowmethod can be used to quickly comprehend the pressure and velocity distribution over a body immersed in or entering the water. However, because it fails to account for the water’s initial acceleration upon entry, the steady-state simulation underestimates the drag force. The submerged flow method’s findings indicate that a sharp nose centre body diminishes drag more successfully. The transition method evaluations for the UAV slender body reveal controllable drag and impact forces. Furthermore, the study demonstrates that wedge-shaped leading edges for the wing-body reduce impact but may not be optimal when considering airlift. As a result, this research provides useful data for air-sea UAV structural design and movement conditions.Item Forced convection heat transfer in micro heat sinks with square and circular configuration(2023-06) Godi, N. Y.; Zhengwuvi, L. B.; Petinrin, M. O.This paper reports the results of three-dimensional numerical optimisation of microchannel heat exchanger with square and circular cooling channels. The objective of the optimisation is to maximise the global thermal conductance or minimise global thermal resistance. Response surface optimisation methodology (RSM) is used in the numerical optimisation. A high-density heat flux (2.5×106𝑊/𝑚2) is imposed at the bottom surface of the unit cell microchannel and numerical simulation carried out using ANSYS Fluent commercial software package. The elemental volume and axial length 𝑁=10 𝑚𝑚 of the microchannel were all fixed, while the width was free to morph. The cooling technique employs single-phase water which flows through the rectangular block microchannel heat sink to remove the heat at the bottom of the microchannels in a forced convection laminar flow regime. The velocity of the fluid pumped across the microchannel axial length is the range 400≤𝑅𝑒𝑤≤500. Finite volume method (FVM) is used to descretised the computational domain and computational fluid dynamic (CFD) code employed to solve a series of governing equations. The effect of channel hydraulic diameter and Reynolds number of water-flow on peak wall temperature and minimised temperature are investigated and reported. The numerical results show that the microchannel with square cooling channel has the highest maximised global thermal conductance than the micro heat sink with circular configuration. The result of the numerical study agrees with what is in the open literature.Item Heat transfer analysis in constructal designed microchannels with perforated micro fins(The Institution of Engineers (India), 2023-04) Godi, N. Y.; Petinrin, M. O.This paper documents 3-D numerical optimisation of combined microchannel heat sink with solid and perforated rectangular fins. Constructal design technique is deployed to construct a geometry with reduced material substrate and the effect on the heat transfer is examined. The goal of the study is to minimise the peak temperature or maximise global thermal performance. The axial length and volume of the microchannel are fixed, while the width is allowed to morph. The microelectronic device placed at the bottom of the combined heat sink emits heat flux q″ and the heat deposited at the bottom is removed using a single-phase fluid (water) of Reynolds number Re w in a forced convection laminar regime. The computational domain is descretised and the mathematical equations that govern the fluid flow and heat transfer are solved using the CFD code. Three unique cases were considered in this study. The influence of design parameters (channel width, external shape, and velocity of fluid applied) on the performance of the combined microchannel heat sink is discussed. The study revealed that the solid material substrates used in the manufacturing of the combined microchannel heat sink can be reduced without necessarily compromising the heat transfer at certain applied Re w . The global thermal conductance of the combined microchannel with no perforation on fins increases by 1.1% higher than the microchannel with 1-rectangular perforation on fins and 0.8% above the heat sink with 2-rectangular perforations on fins. The numerical results validation agrees with what is in the open literature.Item Flow and heat transfer characteristics in channels with piriform dimples and protrusions(Global Digital Central, 2023) Oyewola, O. M.; Petinrin, M. O.; Sanusi, H. O.The flow and heat transfer behaviour of channels with dimples and protrusions of spherical and piriform shapes was numerically explored by solving the Navier-Stokes and energy equations with a CFD software, the ANSYS Fluent 19.3, in the range of Reynolds numbers from 8,500 to 59,000. The values of the Nusselt number and friction factors were estimated and the non-dimensional Performance Evaluation Criterion (PEC) was determined to measure the thermal-hydraulic performance. The results reveal that the piriform protruded channel demonstrated a higher thermal performance with Nusselt number values of 36%, 15%, 23%, and 9% than the smooth, spherical dimpled, piriform dimpled, and spherical protruded channels, respectively. This indicates that heat transfer is enhanced by the turbulent mixing caused by the roughened surfaces of the channels. Nevertheless, the smooth channel had the lowest pressure drop with the friction factor of 20%, 7%, 21% and 27% less than that of spherical dimpled, piriform dimpled, spherical protruded, and piriform protruded channels, respectively. In the Reynolds number range, lower Nusselt number ratios and friction factor ratios were observed in the piriform dimpled channel compared to other enhanced-surface channels. The overall performance based on the thermal-hydraulic analysis indicated that the channel with piriform protrusions performed better with the highest PEC value of 3.77 times higher than the smooth-surface channel.Item Climate change mitigation with carbon capture: an overview(2023) Towoju, O. A.; Petinrin, M. O.The world is at the verge of catastrophe occasioned by the effect of climate change. Drastic action needs to be taken to reverse this ugly trend. Some of the proffered solutions to global warming is the adoption of renewable energy usage and a stop of fossil fuels combustion. However, the low capacity factor and energy return has been the bane on the usage of some renewable energy sources. A leeway however, exists in the technology of removal of greenhouse gases referred to as Carbon Capture. The widely adopted method being at point source because of its high concentration favouring easier processes of removal. This technology has received increased attention over the years as evident from data for the past five years. However, this technology alone cannot guarantee atmospheric CO2 levels required to maintain global temperature rise below the 1.50C mark. Negative emission technology processes of which the Direct Air Capture (DAC) is one needs to be developed. The infancy of the DAC technology and the uncertainties that surrounds its cost still pose as challenges. The cost of removing a tonne of CO2 with DAC technology can be as high as $600, this is unsustainable and has to be drastically reduced. While it is projected that DAC technology can take out 980 Metric Tonne (MT) CO2/annum by 2050, current figures stand at 0.008 MT. It is our view that the development of solid adsorbents and the harnessing of the thermal energy inherent in the sun can be a game changer.