DSpace Repository :: Browsing by Author "Koya, Olufemi A."

Browsing by Author "Koya, Olufemi A."

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Anthropometric characteristics of roadside auto-mechanics: a case study
(Leonardo Journal of Sciences, 2018-01-11) Abiola, Oluranti A.; Oke, Adekola O.; Koya, Olufemi A.
The study evaluated the relevant/corresponding anthropometric characteristics of the people involved in engine-repair activities. The study was carried out on the selected roadside auto-engine repairers along Lagos-Ibadan express way, in Nigeria. This was with a view to providing ergonomic design data for optimal working condition among this set of workforce and redesigning the mechanics inspection-pit. Material and methods: The static and the functional anthropometric characteristics of the mechanics were measured. The data obtained from 110 auto-mechanics, randomly selected, were employed to evaluate efficient design parameter for roadside workstations. Results: The results indicated that inspection-pit is about 1626 mm deep; seat height ranges between 375 mm and 405 mm; optimal work posture sitting is between 483 mm and 622 mm. Conclusions: Adopting the data presented in this paper in optimizing the auto-mechanics working conditions for effective workplace comfort and productivity among the roadside auto-mechanics in Nigeria will be of immense advantage.
Characterisation of pulverised palm kernel shell for sustainable waste diversification
(International Journal of Scientific and Engineering Research, 2013-04) Fono-Tamo, R. S.; Koya, Olufemi A.
The paper presents a report on the physico-thermal properties and elemental composition of pulverized palm kernel shell to enhance its use in engineering applications. Clean palm kernel shell were dried, milled and screened to obtain particles 0.23 mm mean diameter. Experiments were conducted to evaluate the physical and thermal properties of the pulverized palm kernel shell and its differential thermal analysis. Its elemental composition was determined by X-Ray Fluorescent analysis. Test results showed that pulverized palm kernel shell consist mainly of non-ferrous metals. Its bulk density was 560 kg/m3; specific gravity, 1.26. Its thermal properties were characterized by thermal conductivity of 0.68 W/m K; specific heat capacity, 1.98 kj/kg K, and phase change at 101.40C. The report established significant potentials in the diversification of palm kernel shell from waste to fuel in improved combustion systems and as a future element in biomaterial composites.
Computer Aided Plumbing Design
(Academic Journals Inc., USA, 2007) Ajayi, Oluseyi; Ajayi, Oluseyi; Koya, Olufemi A.; Koya, Olufemi A.
This study has been used to eliminate the rigorous activities and time consuming mathematical analysis involved in Plumbing design. The various mathematical steps employed in the design of plumbing systems has been converted into easily interpreted hand user computer program that can be used to generate automatically all the various parameters needed for full design work, when the input data such as head available, various number of fittings, actual length of pipe run and assumed pipe diameter are provided. This has been used to provide a pathway to easy plumbing design
Deformation and Dehulling of Sponge Gourd (Luffa aegyptiaca) Seeds
(Taylor & Francis Group, 2011-02-28) Koya, Olufemi A.; Ogunsina, B. S.; Opeyemi, O. O.
This work presents the compressive strength properties of sponge gourd (Luffa aegyptica) seeds to facilitate the design or adaptation of an appropriate dehuller. The sizes and shape indices of the seed and kernel, and the clearance of the kernel from the seed coat were determined. The seed samples were subjected to uni-axial quasi-static compression tests at 1.0 mm min−1 along the minor and the major axes. The fracture resistance, stiffness modulus, modulus of elasticity, toughness, and maximum elastic deformation of the seed were obtained from the force-deformation curve. The geometric mean diameters varied from 4.0 to 4.5 mm for the seed and 1.6 to 3.9 mm for the embedded kernel; while their corresponding sphericities were 0.64 and 0.62, respectively. The compressive strength of the seed varied with loading orientation. The seed exhibited larger deformation but lower stiffness along the major axis than the minor axis. The force required for rupturing the hull were 95 N along the major axis and 81 N along the minor axis; while the corresponding energy required were 95 and 40 mJ
Deformation and fracture of dika nut (Irvingia gabonensis) under uni-axial compressive loadingc
(International Agrophysics, 2008-01-01) Ogunsina, B. S.; Koya, Olufemi A.; Adeosun, O. O.
Fracture behaviour of dika nut under quasi-static loading along the longitudinal axis and the transverse axis was investigated. The fracture resistance of the nut was measured in terms of average force, deformation and toughness at nutshell fracture, and nut stiffness. Physical dimensions and shape of the nut, to provide for complementary input in design of handling equipment, were also determined. The force required to crack the nut increased with nut diameter but was not significantly different in both loading orientations. The mean cracking force was in the range of 2.06 to 3.67 kN. The compression of the nut exhibited a pronounced linearity between load and deflection. Dika nuts loaded along the transverse axis required less energy for nutshell fracture than those loaded along the longitudinal axis. Minimum toughness occurred with the small size nuts loaded along the transverse axis, thus providing base-line data in future design of an appropriate nutcracker.
Design, construction and testing of a dehuller for African breadfruit (Treculia africana) seeds
(Elsevier, 1999-11-01) Omobuwajo, T. O.; Ikegwuoha, H. C.; Koya, Olufemi A.; Ige, M. T.
The African breadfruit seed is a popular food resource in several parts of West Africa. It is presently being dehulled manually in the absence of a suitable mechanical device. A machine was designed in order to remove the drudgery involved in dehulling the seeds. The machine comprised of a roller which cracks the hull, an oscillating cam follower which removes the cracked hull through repeated shearing against a stationary wall, and an aspiration unit which sifts the hull from the endosperm. A prototype was constructed and tested. Throughput was 64 kg/h; yield, 75%; completely dehulled seeds, 85%; breakage, 1% and sifting efficiency was practically 100%.
Design, fabrication and testing of a cassava pelletizer
(Research in Agricultural Engineering, 2014-11-27) Oduntan, O. B.; Koya, Olufemi A.; Faborode, M. O.
This paper reports on the design of fabrication and testing of a machine for cottage level production of pellets from cassava mash. The pelletizer consists of a barreled screw auger which compresses cassava mash against perforated end plate, through which the pellets are pelletized. The result derived from the calculated design parameters (shaft diameter, tensile stress, torque, screw length, volumetric capacity mass flow rate and power rating) were used for the fabrication. The testing of the pelletizer was determined in terms of throughput of the machine, against the moisture content of the mash (18, 20 and 22% wb), die size (4, 6 and 8 mm) and the auger speed (90, 100 and 120 rpm). Test results showed that the pellets with the best quality attributes were obtained from cassava mash at 18% moisture content (wb) through the 4 mm die at 90 rpm and a maximum throughput of 54 kg/h.
Development and Preliminary Testing of Metering Equipment for Mechanized Yam Sett Planting
(JOURNAL OF AGRICULTURAL ENGINEERING AND TECHNOLOGY (JAET) EDITORIAL BOARD, 2005) Aluko, O. B.; Koya, Olufemi A.
This paper reports the design and laboratory testing of equipment for metering yam setts, as a precursory step in the development of a mechanical yam sett planter. The metering equipment was designed to discharge a yam sett at every 1000 mm of within-row spacing using a ground-wheel drive system. Yam setts flow by gravity from a hopper into a metering drum having an internal helical screw and lift flaps, which discharge the yam setts for planting. Laboratory tests of the prototype gave a metering efficiency of 82.2% with percentages of singles, multiples and skips being 80.5%, 0.2% and 17.7%, respectively. The theoretical field capacity is 0.2 to 0.4 ha h-1 at planting speeds of 2.7 to 5.0 km h-1. The work provides a basis for the future development of a mechanical yam sett planter.
Development of a Machine for Expressing Vernonia amygdalina Leaf Juice
(Ife Journal of Technology, 2012) Oke, A. O.; Koya, Olufemi A.; Akanbi, C. T.
Vernonia amygdalina leaf juice is known for its nutritive value and as food supplement. There is therefore, a need for a simple processing device for the leaf juice expression. This study developed a machine for producing contamination-free V. amygdalina leaf juice. The design of the machine was based on the principle of a pressure deferential applied to the incoming leaf mash compared with that applied to the discharged material. Macerated leaves were compressed through a tapered screw conveyor; whose shaft terminates as a rising but short conical kink. The maximum juice yield of 41.39% was expressed from the leaf mash at pressing pressure and residence time of 6.09 MPa and 11 min, respectively. The throughput of the machine was 9.60 kg/h and the juice extraction rate was 1.86/h at leaf to water ratio of 1: 0.8. The maximum juice expression efficiency was 15.54% at 1: 1.2 leaf to water ratio, 60 rpm constant rotational motor speed and 11.99 kg/h feeding rate. Approximately 26.38% of the inherent moisture content of the leaf was expressed by the machine. It is expected that the machine may be used to express juice from other plant leaves having comparative physical properties. The machine therefore provides a viable technique for mechanical expression of good quality V. amygdalina leaf juice.
Development of an intermittent solar dryer for cocoa beans
(Agricultural Engineering International: CIGR Journal, 2009-07-15) Fagunwa, Ayokunle O.; Koya, Olufemi A.; Faborode, Micheal O.
A solar dryer with thermal energy storage was developed for intermittent drying of cocoa beans. The prototype was built using readily available local materials. Drying mechanism was based on a combination of convective heating and direct radiation, with a provision for controlling the rate of airflow through the beans. The experimental model dehydrated cocoa beans from 53.4 to 3.6% moisture content (wb) in a 72 hours inter-mittent drying process against ambient temperature and relative humidity in the range 25-30 o C and 58-98%, respectively. Quality assessment of the dried beans showed that beans of good quality attributes: pH of 6.35, acid value of 3.40 mg/g, with mildly bitter taste were obtained under free convective drying; whilst, increase in moisture re-absorption and acidic flavour were indicated with forced convective drying. The work, thus, provides a viable system for producing cocoa beans of good quality attributes, comparable with using the traditional sun-drying, but without the associated drudgery.
Dika nut oil as base oil for lubricants—effect of processing conditions on physicochemical properties
(John Wiley & Sons, Ltd, 2013-01) Abidakun, O. A.; Koya, Olufemi A.
The paper presents a report on the effect of processing conditions of Dika nut oil on its physicochemical properties and also on the assessment of the oil for use as biodegradable lubricant. The oil was expressed mechanically from coarsely ground kernel meals at 3 and 9 wt.% moisture content (wet basis), preheated at 75, 100 and 150 °C for 10, 20 and 30 min. The plots showed that the chemical properties of the oil had quadratic and linear relationships with the heating temperature and heating time, respectively. At 95% confidence level, the free fatty acid content, the saponification, the iodine and the acid values of the oil were significantly affected by various processing conditions. The processing conditions therefore showed significant influence on the physicochemical properties of the oil and consequently on its suitability for use as lubricant. Copyright © 2012 John Wiley & Sons, Ltd.
Effect of expression conditions on the yield of Dika Nut (Irvingia Gabonesis) oil under uniaxial compression
(ICCEM, 2012) Abidakun, O. A.; Koya, Olufemi A.; Ajayi, O. O.
Efficient expression of Dika nut oil from the kernel is required for its subsequent use in producing comparatively cheap lubricant. Various factors responsible for proper oil expression include particle size, moisture content, heating temperature, heating time, pressing pressure and pressing time. Sundried Dika kernel ground to two particle sizes (fine: ≤ 1.4 mm and coarse: between 1.4 and 2.8 mm) were conditioned to moisture content of 3, 6 and 9 wt%. Considered in the study, are heating temperature ranging from 50 to 150oC in steps of 25 degrees Celsius and heating time of 5 to 25 minutes in steps of 5 minutes. Pressing pressure of 5 to 25 MPa in steps of 5 MPa and pressing time of 2 minutes interval were also considered. The maximum oil yield was then correlated with the processing conditions. Test results showed that coarse particle gave higher oil yield. Maximum oil yield of 72.2% of the available oil was obtained at 6% moisture content, heating temperature of 100oC and heating time of 10 minutes. Regression analyses of the oil yield with heating temperature, heating time, and pressing gave r2 values of 0.9678, 0.999 and 0.9128. The processing conditions therefore has significantly influence the quantity of oil obtained from Dika kernel.
Evaluation of physico-chemical properties of re-refined lubricating oils obtained from fabricated packed bed reactor
(Taylor and Francis, 2017) Adeyemi, Adebiyi F.; Adebiyi, Fatai M.; Koya, Olufemi A.
This study aimed at fabricating a packed bed reactor (PBR) and evaluating its performance on improving physico-chemical properties of used lubricating oils. The sorbent used was a composite of bentonite, limestone, diatomite, quartz, and wood charcoal in the same ratio by mass. Samples of used lubricating oils from two brands (Mobil Super SAE 20W-50 and Total Quartz 5000 SAE 20W-50) were run through the fabricated PBR. The mean values of the analyzed physico-chemical parameters (kinematic viscosity, viscosity index, flash point, pour point, acid number, base number, iodine value, ash content, density, and refractive index) of the exuded (treated) oils were compared with those of used and virgin oils of the same brand. Apart from the iodine value, the mean values obtained for the treated oil samples are close to those of virgin oil samples. Thet-test results indicated that most of the parameters showed significant difference between their mean values in the used oils indicating distinct properties and hence, good treatment effects, while a good number showed no significant difference between their mean values in the treated Mobil and treated Total oils, indicating similar properties and that the treatment had similar effects on the two brands of oils. Also, various results of cross plots hadR 2 values greater than 0.96, indicating high linear relationships of the impact of the treatment on the various oil samples. The overall results established the high effectiveness of the fabricated PBR for the treatment of used lubricating oils
Experimental Verification of a New Technique for the Dry Separation of Palm Kernel and Shell Mixture
(Innovative Systems Design and Engineering, 2013) Olasumboye, Adewale; Koya, Olufemi A.
Effective separation of the cracked palm nut mixture is an important process in the downstream utilisation of the constituent palm kernel and shell in some existing and emerging agro-economy. Whilst, the conventional wet separators are sophisticated and energy inefficient, the dry systems are at experimental stages and are inadequate for separating kernel and shell of comparable sizes. However, the difference in the path variables of particles of same size, but different shapes, in circular motion, suggests the possibility of separating the dry mixture in a rotating trammel with a co-axial spout. Based on the theory, the study investigated the dispatch angles for palm kernel and shell from a friction lining on the inner curved surface of drums of different diameters and rotating speeds. A built experimental facility allowed estimation of the dispatch angle for particles placed on the lining. The results show that palm kernels oscillate and move axially with the dispatch angle increasing with the drum diameter, but consistently less than 90o for the different diameters and speeds of the drum. The shells are dislodged at higher dispatch angles and in curvilinear trajectories away from the drum surface, causing a separation of the mixture. It is concluded that the experimental data are in good agreement with the theory and that the theory is sufficiently adequate for the determination of the design parameters of a proprietary separator.
Hydro power potentials of water distribution networks in public universities: A case study
(Leonardo Electronic Journal of Practices and Technologies, 2017-01) Koya, Olufemi A.; Oladosu, Temidayo L.
Public Universities in Southwestern Nigeria are densely populated student-resident campuses, so that provision of regular potable water and electricity are important, but power supply is not optimally available for all the necessary activities. This study assesses the hydropower potential of the water distribution networks in the Universities, with the view to augmenting the inadequate power supplies. The institutions with water distribution configuration capable of accommodating in-pipe turbine are identified; the hydropower parameters, such as the flow characteristics and the pipe geometry are determined to estimate the water power. Global positioning device is used in estimating the elevations of the distribution reservoirs and the nodal points. The hydropower potential of each location is computed incorporating Lucid® Lift-based spherical turbine in the pipeline. From the analysis, the lean and the peak water power are between 1.92–3.30 kW and 3.95–7.24 kW, respectively, for reservoir-fed distribution networks; while, a minimum of 0.72 kW is got for pipelines associated with borehole-fed overhead tanks. Possible applications of electricity generation from the water distribution networks of the public universities are recommended.
Mathematical modelling of palm nut cracking based on Hertz's theory
(Academic Press, 2005-08) Koya, Olufemi A.; Faborode, M. O.
A mathematical model based on Hertz's theory of contact stress was developed for the prediction of force required to break the palm nut. Using nuts subjected to a uniaxial compression stress, in their lateral axis between rigid parallel plates, and those propelled to impinge a rigid cylindrical seat along its lateral axis, experimental verification of the model was conducted comparing the theoretical predictions with estimates from the representations of conventional methods employed in nut cracking. Properties including size, shape and mass, required in the derived model were determined for two varieties of the palm nut. Material stiffness was obtained from the force–deformation curve. Regression analysis showed an exponential variation of the cracking force with nut deformation. Material stiffness obtained was 654 N/mm and 303 N/mm for the ‘Dura’ and ‘Tenera’ nuts, respectively. The respective ranges of geometric mean diameters were 17·07–27·68 mm and 22·32–26.51 mm. There was no significant variation of nut sphericity with size or variety. Force prediction from the Hertzian model proposed gave good prediction of cracking force that was not significantly different from that obtained from a centrifugal nutcracker driven at 1500 min−1, with a 40 cm diameter cracking chamber
Numerical analysis of lift-based in-pipe turbine for predicting hydropower harnessing potential in selected water distribution networks for waterlines optimization
(Elsevier, 2018-08-01) Oladosu, Temidayo L.; Koya, Olufemi A.
The research models and simulates in-pipe turbine hydropower harnessing possibilities in water distribution networks of the sites under investigation considering in-pipe lift-based spherical turbine. The hydrofoil profile of the turbine is generated using National Advisory Committee for Aeronautics (NACA) aerofoil generator. Consequently, a Computer-Aided Design (CAD) model of the in-line liftbased spherical turbine is then developed and simulated, based on the peak and lean period of the volumetric discharge rates using commercial computational fluid dynamics software (Autodesk Simulation CFD ). The time series of power outputs are computed from the time series of discharge variations. A liftbased spherical turbine with NACA 0020 foil cross-section appears appropriate for extraction of energy in the water distribution pipelines. Furthermore, the minimum and maximum percentage head loss due to insertion of the turbine is about 1.94% at lean flow rates and 9.70% at the peaks for 250 mm pipelines. The available power was found out to depend on the density of the turbine blades material, flow rate, and the pipe diameter. The estimated lean and the peak electric power are about 415 and 1663 W, respectively, using aluminium foil blades while stainless steel foil produces about 242 and 1080 W in the 250 mm pipe.
Palm nut cracking under repeated impact load
(J. Appl. Sci, 2006) Koya, Olufemi A.
Cracking a whole palm nut under repeated impact load, with the object of minimizing kernel breakage, was modeled and tested. The models were based on the conservation of energy impacted on the nut by a falling weight, or the kinetic energy of a moving nut and the strain energy required in fracturing the nutshell. One of the two models predicts the falling height required to crack a nut, in terms of stiffness, maximum deformation and size of the nut and the load cycles. The second model predicts the hurling speed required to crack a nut, in terms of stiffness, maximum deformation, mass and size of the nut and the load cycles. Experimental verification, which is in good agreement with the theory showed significant reduction in kernel breakage when palm nuts were subjected to low but repeated impact.
The performance evaluation of a cassava pelletizer
(Canadian Journal on Science and Industrial Research, 2012) Oduntan, O. B.; Koya, Olufemi A.; Faborode, M. O.; Oduntan, A. O.
This paper reports on the development and performance evaluation of a machine for cottage level production of pellets from cassava mash. Cassava flour was produced by peeling, grating and drying freshly harvested cassava tubers. Experiments were conducted to determine the physical properties, such as moisture content, particle size distribution and bulk density and the chemical composition of the flour. The flour was mixed with water at different blend ratios to form cassava mash of different moisture contents. A cassava pelletizer was then developed incorporating relevant properties of the flour. The pelletizer consists of a barreled screw auger, which compresses cassava mash against a perforated end plate, through which the pellets are extruded. The barrel is encased in a co-axial counter flow heat exchanger to provide cooling for the system. The performance of the pelletizer was evaluated in terms of the density, durability, crushing strength and cyanide content of the pellets, and the throughput of the machine, against the moisture content of the mash (18, 20 and 22 % w.b.), die size (4, 6 and 8 mm) and the auger speed (90, 100 and 120 rpm). Test results showed that the bulk density and the durability of pellets decreased while the moisture content increased significantly (p<0.05) and separately with increasing die size and moisture content of cassava mash. The pellets with the best quality attributes were obtained from cassava mash at 18% moisture content (w.b.) extruded through the 4 mm die at 90 rpm and a maximum throughput of 54 kg/hr. The pellets exhibited a bulk density of 635 kg/m3 , 15% moisture content (w.b.) crushing strength of 34.24 MPa and a high durability (85.7%). The machine, thus, provides a significant leverage in the utilization of cassava as pelletized animal feed.
Removal of metals from flat lubricating oils using a fabricated packed-bed reactor
(Taylor & Francis, 2018-03-19) Adebiyi, F. M.; Adeyemi, A. F.; Koya, Olufemi A.
Packed bed reactor (PBR) was fabricated and its performance in removing metals from used (flat) lubricating oils was evaluated. A blend of locally produced diatomaceous materials was employed as sorbent. Flat lubricating oils from two brands (Mobil Super SAE-20W-50 and Total Quartz 5000 SAE-20W-50) were run through the PBR. Concentrations of the analysed metals in the used and treated oils were measured using Atomic Absorption Spectrophotometer and the results compared with those of unused (virgin) oils. Zinc, Mg, Ca, Na and K were detected in virgin oils; while all the analysed metals were detected in the treated and used oils but are of higher concentrations in the used oils. Cross plots have R2 values > 0.96, indicating high linear relationships of the impact of the treatment on the used oils. T-test results indicated that most of the metals showed significant differences between the mean values of the treated and used oils, indicating good treatment effects; while most of them indicated no significant differences between the mean values of the brands of oils used, indicating similar treatment effects on the two brands of oils. These results confirmed the high efficacy of the fabricated PBR for the purpose of recycling used oils.

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