Prof. K.R. Ajao
@unilorin.edu.ng
Professor, Faculty of Engineering and Technology
University of Ilorin, Nigeria
Kajogbola Rasaq Ajao is a Professor of Mechanical Engineering with specialization in Energy at the University of Ilorin, Nigeria. My research interest covers Renewable Energy Systems, Energy Modeling, Energy Efficiency and Reverse Engineering.
EDUCATION
PhD, Mechanical Engineering
RESEARCH, TEACHING, or OTHER INTERESTS
Mechanical Engineering, Renewable Energy, Sustainability and the Environment
Scopus Publications
Scopus Publications
H.A. Ajimotokan, N.S. Saidu, M.A. Aladodo, K.O. Oladosu, O.D. Samuel, K.O. Abdulrahman, A. El-Suleiman, Y.S. Salihu, and K.R. Ajao
Elsevier BV
H. A. Ajimotokan, K. R. Ajao, A. B. Rabiu, T. Yahaya, A. Nasir, I. K. Adegun, and O. T. Popoola
Informa UK Limited
ABSTRACT Though the trilateral cycle (TLC) is a promising heat recovery-to-power cycle, its application has not been widely accepted or commercialised due to some thermodynamic feasibility concerns. This study examined the performance analysis and sensitivity of the system parameters on the thermodynamic performance of the TLC power generator systems for waste heat recovery-to-power generation. Thermodynamic models of the simple, recuperative, reheat and regenerative TLCs were established. Performance analysis and sensitivity of the system parameters on the cycles’ performance were conducted at the expander inlet temperature of 453 to 473 K, expander pressure of 2 to 3 MPa and expander isentropic efficiency of 50% to 100%. The expander inlet temperatures, pressures, and its isentropic efficiencies have significant effects on the thermodynamic efficiencies and net work output of the cycles. At 473 K cycle high temperature, the thermal efficiencies of the cycles increase from 20.13% to 21.97%, 23.29% to 23.91%, 20.62% to 22.07% and 20.66% to 22.9% for the simple, recuperative, reheat and regenerative TLCs, respectively. Their corresponding net power outputs varied from 131.6 to 134.1 kW, 145.9 to 152.2 kW, 113.8 to 124.1 kW and 124.9 to 130.5 kW, respectively. The cycles’ thermodynamic performance increased with an increase in expander inlet temperature, expander pressure and expander isentropic efficiencies.
Kajogbola R. Ajao, Segun E. Ibitoye, Adedire D. Adesiji, and Esther T. Akinlabi
MDPI AG
The additive manufacturing process creates objects directly by stacking layers of material on each other until the required product is obtained. The application of additive manufacturing technology for teaching and research purposes is still limited and unpopular in developing countries, due to costs and lack of accessibility. In this study, an extruding-based 3D printing additive manufacturing technology was employed to design and construct a low-cost-high-accessibility 3D printing machine to manufacture plastic objects. The machine was designed using SolidWorks 2020 version with a 10 × 10 × 10 cm3 build volume. The fabrication was carried out using locally available materials, such as PVC pipes for the frame, plywood for the bed, and Zinc Oxide plaster for the bed surface. Repetier firmware was the operating environment for devices running on the computer operating system. Cura was used as the slicing software. The fabricated machine was tested, and the printer produced 3D components with desired structural dimensions. The fabricated 3D printer was used to manufacture some plastic objects using PLA filament. The recommended distance between the nozzle tip and the bed is 0.1 mm. The constructed 3D printer is affordable and accessible, especially in developing nations where 3D printing applications are limited and unpopular.
A.A. Adeleke, J.K. Odusote, P.P. Ikubanni, O.A. Lasode, O.O. Agboola, A. Ammasi, and K.R. Ajao
Elsevier BV
Laniyi L. Ladokun, Bolaji F. Sule, Kajogbola R. Ajao, and Adeniyi G. Adeogun
Informa UK Limited
Peter Pelumi Ikubanni, Adeolu Adesoji Adediran, Adekunle Akanni Adeleke, Kajogbola Rasaq Ajao, and Olayinka Oluwole Agboola
Trans Tech Publications, Ltd.
The effect of quenching on the mechanical properties of medium carbon steels using coconut (CW) water, pap water (PW) and spent engine oil (SPE) which have been largely considered as wastes was investigated. All specimens were normalized at a temperature of 840 in order to remove residual stresses induced during machining operations. Various specimens were heated to ranges of 730-790 and soaked for the range of 30-60 minutes respectively. Brinnel hardness tester was used to obtain the hardness values while Testometric M500-50AT model machine was used for the tensile test of the specimens. The highest hardness value (609.97 BHN) was obtained from the specimen heated to 790 quenched in pap water as compared with 166.4 BHN for the normalized as-received sample. The yield (YS) and ultimate tensile (UTS) strengths of the quenched specimens were better than the normalized as-received sample. SPE-quenched samples yielded the highest YS and UTS combined. The hardness value increased while YS and UTS decreased with soaking time for different temperatures. The highest hardness value for the specimens was obtained from coconut and pap water. Rather than been considered as wastes, coconut water, pap water and spent engine oil can improve the mechanical properties of medium carbon steel when used as quenching media.
I. Ibrahim, K.R. Ajao, and S.A. Aremu
University of Zielona Góra, Poland
An industrial process such as wheat processing generates significant noise which can cause adverse effects on workers and the general public. This study assessed the noise level at a wheat processing mill in Ilorin, Nigeria. A portable digital sound level meter HD600 manufactured by Extech Inc., USA was used to determine the noise level around various machines, sections and offices in the factory at pre-determined distances. Subjective assessment was also mode using a World Health Organization (WHO) standard questionnaire to obtain information regarding noise ratings, effect of noise on personnel and noise preventive measures. The result of the study shows that the highest noise of <i>99.4</i> dBA was recorded at a pressure blower when compared to other machines. WHO Class-4 hearing protector is recommended for workers on the shop floor and room acoustics should be upgraded to absorb some sounds transmitted to offices.
K. R. Ajao, , R. M. Ambali, M. O. Mahmoud, , and
International Hellenic University
The optimal tilt angle of solar photovoltaic panel in Ilorin, Nigeria was determined. The solar panel was first mounted at 0o to the horizontal and after ten minutes, the voltage and current generated with the corresponding atmospheric temperature were recorded. The same procedure was repeated for 2o to 30o at a succession of 2o at ten minutes time interval over the entire measurement period. The result obtained shows that the average optimal tilt angle at which a solar panel will be mounted for maximum power performance at fixed position in Ilorin is 22o. This optimum angle of tilt of the solar panel and the orientation are dependent on the month of the year and the location of the site of study.
J.A. Olorunmaiye, K.R. Ajao, and I.S. Omolehin
Computers, Materials and Continua (Tech Science Press)
ABSTRACT Hourly dry-bulb temperatures for Ikeja and Ilorin were obtained from the Nigerian Metrological Services Agency, Oshodi, Lagos, for the years 1995-2008. Statistical analyses were carried out on the data to obtain the average hourly temperatures for each month, the average temperature for each month, and the average temperature for the four warmest months (along with the standard deviations for each case). The average hourly temperatures were compared with those obtained by Ariyo for the two locations for the year 1978-1992. The 1%, 2½%, and 5% design temperatures obtained from the average temperature for the four warmest months, assuming the temperature distribution follows a normal distribution pattern, were also compared with those obtained by Ariyo for 1978-1992, as well as with those obtained by Shoboyejo and Shonubi for 1951-1965. It was observed that the average hourly temperatures were higher in the Shoboyejo-Shonubi work than those obtained by Ariyo for all the months for both locations. T...
Bolaji F. Sule, Kajogbola R. Ajao, Habeeb A. Ajimotokan, and Mohammed K. Garba
Emerald
PurposeThe purpose of this study is to examine the electricity consumption trend in residential buildings using incandescent lamps and retrofitting with compact fluorescent lamps (CFLs).Design/methodology/approachQuestionnaires were administered to capture the necessary data from three randomly selected residential estates in Ilorin, Nigeria. In total, 8,840 sampled incandescent lamps were retrofitted with CFLs. The electric energy in kilowatt hour (kWh) consumed prior to replacement for three months was compared with kWh consumption after retrofitting and analyzed employing t‐tests.FindingsThe three‐month average electricity consumption of ten households for the University of Ilorin GRA quarters and Lower Niger River Basin staff quarters pre‐ and post‐installation were 20,259 and 13,010 kWh, and 46,891 and 29,588 kWh, respectively. Results show that there were significant differences between the observed and tabulated values for the pre‐ and post‐installation of CFLs, respectively, at 5 per cent confidence level. About 40 per cent reduction in electricity consumption was achieved through deployment of CFLs in the residential households.Originality/valueThis paper demonstrates how retrofitting of incandescent lamps with CFLs can bring about possible reduction in electricity consumption in residential households in Nigeria.
B.F. Sule, K.R. Ajao, and H.A. Ajimotokan
Computers, Materials and Continua (Tech Science Press)
ABSTRACT Energy utilization is substantial in the household sector because there is considerable energy loss due to the use of traditional incandescent lighting. The aim of this article is to demonstrate how successful replacement of incandescent lamps with compact fluorescent lamps (CFLs) can bring about a possible reduction in electricity consumption in residential households. Questionnaires were administered to capture the needed data from four randomly selected residential estates in Ilorin, Nigeria, and these were analyzed using statistical analysis. Results obtained show that University of Ilorin GRA Quarters (Estate A) had 66 households, with a total of 1,082 (90.09%) incandescent lamps, 73 (6.07%) fluorescent lamps, and 10 (0.83%) halogen lamps, while there were 36 (3%) CFLs. The Lower Niger River Basin (Estate B) had 156 households, with a total of 2,767 (79.99%) incandescent lamps, 173 (5.01%) fluorescent lamps, and 485 (14.02%) halogen lamps, while there were 34 (0.98%) CFLs. The Mandate I&II H...
J. A. Olorunmaiye, D. O. Ariyo, A. D. Ogunshola, and K. R. Ajao
Begell House
The climate is one of the factors on which the energy required to cool a building depends. Hourly dry-bulb temperature and relative humidity data for fifteen years (1978 – 1992) were obtained for Ilorin and Ikeja. From statistical analysis of the data, it was found that the mean dry bulb temperature and the 1, 2.5 and 5 % design dry-bulb temperature used for air-conditioning cooling load calculation were higher than the corresponding values published in 1974 from statistical analysis of weather data for the fifteen year period of 1951 – 1965. This shows that more energy will be required for cooling buildings if the trend of global warming continues. One way to reduce global warming is by using bio-fuels. A four stroke spark-ignition engine was run on pure gasoline, 5 % ethanol to 95% gasoline, 10 % ethanol to 90 % gasoline, 15 % ethanol to 85 % gasoline and 20 % ethanol to 80 % gasoline. When the engine ran on pure gasoline, it developed a maximum torque of 10.7 Nm, a brake power of 3141.6 W and a brake thermal efficiency of 25.91 %. Each of these performance parameters reduced as the percentage of ethanol increased. For the 20 % ethanol to 80 % gasoline blend the corresponding values of the performance parameters obtained were 10.2 Nm, 2827.44 W and 21.75 %. Even though the performance of the engine declined as the percentage of ethanol increased, the emission of less green house gases is enough motivation to use bio-fuels.
K. R. Ajao and I. K. Adegun
Begell House
The parameterization, installation and testing of a locally developed three-bladed horizontal-axis wind turbine was carried out. The turbine blades were fabricated from Mansonia Altissima wood because of its availability, good strength, and resistance to both fatigue and soaking, with a rotor swept area of 3.65 sq. metres and the blade angle of attack was experimentally determined to be 7. The turbine was installed on the roof top of University of Ilorin, Faculty of Engineering Central Workshop Building at a hub height of 14.9 metres from the ground level while the turbine generator was sourced locally. The direct current (d.c.) power output of the test turbine was measured at the battery bank terminal by a Power Analyzer and a direct current (d.c.) to alternating current (a.c.) inverter converts the d.c. power output to a.c. power and was measured by a digital Wattmeter. An anemometer with a data logger installed on a meteorological tower (MET) measured the wind speed and direction over the test period. The cut-in wind speed, that is, the speed at which the wind turbine starts to produce power was determined to be 3.5 m/s. One minutes averages of wind speed and power output was used to determine the power curve for the wind turbine. Measured power increase consistently with increased wind speed and the power curve obtained compared fairly well with standard power curves. [Journal of American Science 2009;5(5):71-78]. (ISSN: 15451003).
K. R. Ajao, H. A. Ajimotokan, O. T. Popoola, and H. F. Akande
Informa UK Limited
An analysis of Nigeria’s electricity supply problems and prospectsfound that the electricity demand in Nigeria far outstrips the supply,which is epileptic in nature. The acute electricity supply hinders thecountry’s development, notwithstanding the availability of vast naturalresources in the country. Nigeria is endowed with abundant renewableenergy resources, the significant ones being solar energy, biomass, wind,small and large hydropower with the potential for hydrogen fuel, geo-thermal and ocean energies. Decentralized energy is the production ofelectricity at or near the point of use, irrespective of size, fuel or technol-ogy. The adoption of renewable energy technologies in a decentralizedenergy manner, especially for rural communities and in stand-aloneapplications, will improve electricity supply and enhance the overalleconomic development.