FACULTY OF TECHNOLOGY
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Item Production and characterisation of Al-Mg-Cr alloy for machine tool applications(2020-08) Ajide, O. O.; Ogochkwu, C. D.; Akande, I. G.; Petinrin, M. O.; Ismail, O. S.; Oluwole, O. O.; Oyewola, O. M.Industrialisation and technological advancement are immensely influenced by materials development and innovation. Recent studies have shown that the use of some specialised alloying elements can be explored for enhancing properties of monolithic alloys. This study focuses on the production and characterisation of Al-Mg-Cr alloy suitable for machine tool applications. Al-Mg-Cr alloy was developed using sand mould and two-step stir-casting method. Chromium was added to Al-Mg alloy at varying contents of 0.5, 1.0, 1.5 and 2.0 %. Tensile tests were carried out in accordance with ASTM E8 to determine ultimate tensile strength (UTS), percentage elongation and modulus of elasticity at varying chromium contents. The evolved microstructures were examined using an optical microscope (OPM). The study revealed that the alloy containing 1.5% chromium exhibited maximum ultimate tensile strength of 135.15 MPa and percentage elongation of 3.76 %. However, Al-Mg-Cr alloy containing 1.0% chromium exhibited best combination of UTS (123.98 MPa), percentage elongation (3.32%), modulus of elasticity (12.11 GPa) and microstructural features. Five samples of Al-Mg-1.0Cr alloy were thereafter heat treated at different temperatures from 250 ˚C to 450 ˚C. The heat treated samples were also subjected to tensile tests and optical microscopy. The results were compared with the as-cast Al-Mg-1.0Cr alloy. The results showed that heat treatment of Al-Mg-Cr alloy had adverse effect on their mechanical and microstructural properties. The outcome of this study has shown that chromium as alloying element has potentials for enhancing tensile and microstructural characteristics of Al-Mg based alloys, and the benefit can be explored for machine tool applications.Item Numerical modelling of thermal distribution control in a furnace(2018) Petinrin, M. O.; Ajide, O. O.; Dare, A. A.; Oyewola, O. M.; Ismail, O. S.Application of control to heat treatment processes helps to achieve the desired mechanical properties of materials but improper controller design is a major problem causing short lifespan of components of locally made furnaces. In this study, the numerical control of the temperature distribution within a furnace cavity was carried out using COMSOL Multiphysics and Simulink. Six sensor points within the furnace cavity (with and without specimen) were selected and each point was consecutively used to observe the time response of the sensor to the desired temperature. The results from the time response analysis indicated uneven temperature distribution within the furnace with points located at the corners of the furnace recording the highest temperature rise while points at the centre of the furnace or within the specimen having the lowest temperature. Thus, the best position for a sensor is at any corner of the furnace to protect the components of the furnace from damage.Item Control modelling of coupled shell and tube heat exchangers using combined neural network and fuzzy logic(2022) Petinrin, M. O.; Oke, O. S.; Adebayo, A. S.; Towoju, O. A.; Ismail, O. S.Control of the temperature of the outlet fluid in heat exchanger network is very important to maintain safety of equipment and meet the optimal process requirement. Conventional PID controllers have the limitations of meeting up with wide range of precision temperature control requirements, and then the predictive controllers have recently emerged as promising alternatives for advanced process control in heat exchanger systems and other industrial applications. This paper focuses on the control of output temperature of coupled shell and tube heat exchanger by combining fuzzy logic and Neural Network control system. To achieve effective control, transfer functions from the energy balance equations of the heat exchanger unit and other components were obtained. Simulation of the control process was carried out using Simulink interface of MATLAB. The time response analysis in comparison with variants of conventional PID controllers shows that combination of Neural Network and fuzzy logic controllers can efficiently improve the performance of the shell and tube heat exchanger system while in with 0.505% overshoot and less settling time of 12.74 s, and in parallel with the same overshoot of 0.505% and settling time of 11.37 s. The demonstration of the lower error indices of the neuro-fuzzy controlled system also indicated its better performance.Item Minimisation of exergetic cost of steam pipeline insulation(2020-04) Petinrin, M. O.; Osisanya, F. O.; Adebayo, J. K.; Ajide, O. O.; Dare, A. A.; Ismail, O. S.This paper presents the optimization study of steam pipeline insulation with three insulation materials: EPS, XPS and rockwool. The steam pipelines considered were single straight pipe, two-branch and three-branch networks with effects of pipe length and multilayered insulation on exergy loss, thickness and its attendant cost of insulation. Scaled exergetic cost model was developed and minimized to determine the optimum insulation thickness for pipeline carrying steam at inlet temperature of 200°C. For the same thickness of layer in composite insulation, preliminary analysis indicated that the best order of arrangement from the pipe outside surface is XPS-EPS-Rockwool. The optimum thickness of insulation and associated cost decreased with increase in flow rate of the steam but they increased with the pipe length. For different pipe lengths, the multilayer composite gave fairly smaller optimum insulation thicknesses and costs as compared with monolithic insulation of pipe with each of the insulation materials. The study also showed that each pipe in the multiple pipe networks had its own peculiar optimum thickness for each insulation layer in the multilayered composite to ensure pipe-end thermal quality of the steam pipeline.Item Optimal parameter in theeconomic pipeline distribution of jatropha oil(Society for Interdisciplinary Research, 2011-06) Durowoju, M. O.; Ismail, O. S.; Oladosu, K. O.Due to gradual depletion of world petroleum reserves and the environmental pollution of increasing exhaust emissions, there is an urgent need to develop alternative energy resources, such as biodiesel fuel. One way of reducing the biodiesel production costs is to use the less expensive feedstock containing fatty acids such as inedible oils, animal fats, waste food oil and by products of the refining vegetables oils. The fact that Jatropha oil cannot be used for nutritional purposes without detoxification makes its use as energy or fuel source very attractive as biodiesel. Due to its high flash point, Jatropha oil has certain advantages like greater safety during storage, handling, and transport. However, this may create problems during starting. The viscosity of Jatropha oil is less as compared with other vegetable oils but it is higher than diesel. To lower the viscosity and density of Jatropha oil, preheating is necessary prior to pumping. However, additional costs are incurred through heating and heating cost increases with temperature. This suggests the existence of an optimum temperature to which the fluid can be heated at minimum cost. This work is therefore, a study carried out to determine the optimum heating temperature for a given pipe diameter. The study of fluid flow was carried out and modified to incorporate cost concept to produce a mathematical model that predicts the economic heating temperature. The effect of pipe diameter on these temperatures was investigated via a computer code developed in Matlab 7.3 programming language. The result obtained showed that as the pipe diameter increased from 0.042m to 0.062m, the optimum heating temperature is maintained at 30°C. Results of this nature can be utilized in industries where pumping of Jatropha oil as an alternative fuel is sine-qua-non.Item Assessment of large-scale motion in turbulent boundary layer subjected to a short roughness strip(Begell House, Inc, 2011) Oyewola, M. O; Ismail, O. S.; Adaramola, M. S.Measurements have been made in a turbulent boundary layer which is subjected to a short roughness strip, with the view to examine the influence of short roughness strip on the large scale motion. This is quantified through the analysis of autocorrelation of the fluctuating velocities in the streamwise and wall-normal downstream of a roughness strip. Also, distributions of cross correlation functions are presented. The results indicate that, reference to the smooth wall, there are noticeable changes in the distributions of autocorrelation and cross correlation functions, suggesting that the large scale motion is altered as a result of the modification of the structure near the wall in the presence of the roughness element. This change extends to significant portion of the boundary layer.Item Effects of pipes corrugated shapes on the friction factor(2012-07) Ismail, O. S.; Tairu, O.OCorrugated pipes are pipes with walls of rough surfaces consisting of discrete grooves periodically disposed along the flow direction and commonly use in engineering application such as irrigation, delivery devices to main distribution ducts as in transport of Liquid Natural Gas from ships to the mainland distribution network and heat exchanger in heating, ventilation, air-conditioning etc. The simulation of turbulent, incompressible, isothermal and single-phase flow is considered for five geometric configurations of corrugated surfaces with the different groove heights, length and spacing were evaluated in order to compare their influence on the friction factor. The numerical analysis was carried out using computational fluid dynamics, and the two-equation turbulence models was used to compute the friction factors and Reynolds number for comparison. The results shows that the friction factor is not solely depend on the roughness height but also on the thickness ofthe roughness and space between successive roughness.Item Aircraft Disasters- roles of materials(2009) Asafa, T. B.; Durowoju, M. O.; Ismail, O. S.Aircraft disaster has been in existence since air was conquered by man as a means of transportation. 487.5 million and 874.4 millions of cumulative departures and flight hours respectively have been estimated since 1959. Analysis of aircraft failure based on 5,149 on-board fatalities recorded shows that 13% of total aircraft accident was caused by mechanical failure while loss of control was responsible for over 31% of onboard fatalities. Aircraft accident is known to be most fatal during take-off and landing phase contributing about 49% while onboard fatality during cruise is about 19%. In this work, reviews of aircraft disasters were made via Fractographic examination, SEM and finite element modeling. It must be stated that few of aircraft failures which are not material related are not considered in this review. The review focused on material related failure which have been analyzed, accepted and published in reputable journals.Item Dynamic modelling of a vapour compression air conditioner system(2009) Ajabge, I. O.; Ismail, O. S.Modelling is a very important tool for understanding complex problems. A model plays a fundamental role in the analysis, design and development of complex systems, especially when physical testing and experimentation are not feasible - or not possible at all. Modelling technology holds tremendous promise for reducing costs, improving quality, and shortening the time-to-market for manufactured goods. Unfortunately, this technology still remains largely underutilized by industries today, especially in Nigeria. Analyzing vapour compression air conditioners for their capability of achieving a desired performance level is a difficult and essential task that must be undertaken by the specifying engineer. This involves an understanding of what is required for the particular air conditioning application as well as what the particular grouping of equipment components into the system are or, more importantly, are not capable of doing. A detailed dynamic model of a vapour compression air conditioner system is therefore developed. The Model components are mathematically described, considering energy balances within the system. Ambient wet and dry bulb temperature and solar radiation are the few required inputs. Output measures of performance of the system such as system temperatures, energy flows, and coefficient of performance can be predicted. Simultaneously, a software package, "AJBSIM' has been developed to simulate the steady state performance of the equipment, ease and hasten the calculation expedience involved as well as enable parametric studies to be conducted.Item Performance evaluation and environmental impact assessment of systems with waste exergy emissions(IJSER, 2012-07) Ismail, O. S.; Adewole, O.SThe transformation and utilization of non-renewable energies involves irreversibility which makes our system less efficient. The environmental impact potential is equivalent to the work potential of the emissions.The irreversibility of inefficient systems has Global Warming Potential or environmental impact potential as wasted exergy is not always in equilibrium with the environment. Most literatures have either considered the optimization of thermodynamic systems for better efficiency or environmental effect of the transformation and utilization of energy separately. Focusing more on systems with waste emissions, the exergy lost to the environment through their waste emissions have environmental impact potential. This work reviews literatures on exergy analysis done for systems with waste emissions (heat and gaseous) and some literatures on environmental impact of human activities like gas flaring. The work further proposes more research into the development of a system that would integrate the environmental impact Potential into the calculation of exergetic efficiency of any thermodynamic system. This is to put researchers on their feet to come up with systems that will be exergy efficient and environmentally friendly. Exergy analysis being a good Environmental Impact Indicator can be used to both optimize our systems and also reduce the pollution of our environment.