Habeeb A. AJIMOTOKAN
@unilorin.edu.ng
Associate Professor, Faculty of Engineering and Technology
Others
University of Ilorin
RESEARCH, TEACHING, or OTHER INTERESTS
Energy Engineering and Power Technology, Renewable Energy, Sustainability and the Environment
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Satish Geeri, Aditya Kolakoti, Olusegun David Samuel, Mohamed Abbas, Peter Alenoghena Aigba, Habeeb A. Ajimotokan, Christopher C. Enweremadu, Noureddine Elboughdiri, and M.A. Mujtaba
Elsevier BV
Temitayo Samson Ogedengbe, Sunday Adeniran Afolalu, Omolayo Michael Ikumapayi, Sulaiman Abdulkareem, Habeeb Ajimotokan, and Moses Eterigho Emetere
EDP Sciences
Machining is an indispensable part of production technology with cutting tool. with cutting tool playing key roles in its operations. The demand for more efficient cutting tool increases continuously with technology. Most of the cutting tools in use are imported and the cost of replacement is high. This problem had resulted in series of studies into the development of cutting tools from indigenous materials, particularly agrowastes. This study was a review of the various tool development approaches using various agrowaste types. The challenges and recorded successes as well as gaps in knowledge have also been identified. Summarily, the use of cutting tools developed from steel types that have been case-hardened by agro wastes is a viable alternative that can be explored for use in machining technology.
K.O. Oladosu, S.A. Babalola, M.W. Kareem, H.A. Ajimotokan, M.Y. Kolawole, W.A. Issa, A.S. Olawore, and E.A. Ponle
Elsevier BV
A. A. Samuel, A. Sulaiman, H. A. Ajimotokan, S. E. Ibitoye, T. K. Ajiboye, T. S. Ogedengbe, and I. O. Alabi
African Journals Online (AJOL)
This study examined the morphology and microstructural evolution of resin-bonded palm kernel and coconut shell grain-based abrasive grinding wheels and their physico-mechanical and tribological properties. Raw palm kernel shell (PKS) and coconut shell (CNS) samples were obtained, sorted, sun- and oven-dried, pulverised, and screened into fines of 250, 500 and 850 μm grain sizes, and blended at PKS to CNS mixing ratios of 1:0, 0:1, 1:2, 1:1 and 2:1, respectively. The blended grains, on a weight basis of the total aggregates, were bonded with 25 wt.% polyester resin and hardened and catalysed with 1.5 wt.% cobalt compound and methyl-ethyl ketone peroxide. The aggregates were moulded and compressed at a constant pressure of 18 MPa, ejected, and room-cured before being oven-cured to produce the wheels. The microstructural, water absorption, impact, flexural, hardness, and wear rate properties of the produced samples were evaluated. The properties studied were significantly influenced by grain sizes and mixing ratios of the PKS and CNS in the wheels. The least hardness value, 6.42 HRB, and wear rate, 0.44 mg/m were found in wheels produced from aggregates with pure PKS content with 850 and 250 μm grain sizes, respectively. The wheels' durability qualities suggest they could be used as abrasive grinding wheels, in particular, for wood cutting and finishing processes.
Habeeb Adewale Ajimotokan
Springer International Publishing
Habeeb Adewale Ajimotokan
Springer International Publishing
Habeeb Adewale Ajimotokan
Springer International Publishing
Habeeb Adewale Ajimotokan
Springer International Publishing
Habeeb Adewale Ajimotokan
Springer International Publishing
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.
Habeeb A. AJIMOTOKAN, Isiaka AYUBA, and Hassan K. IBRAHIM
Journal of Thermal Engineering
The trilateral cycle (TLC), a promising alternative waste heat recovery-to-power cycle, is receiving increasing attention due to feats such as the high thermal match between the exergy of the heat source temperature profiles and its working fluid. Although the TLC has neither been broadly applied nor commercialised because of its thermo-economic feasibility considerations. This study examined the thermo-economic analysis of different TLC power generator configurations; i.e., the saturated subcritical simple (non-recuperative) and recuperative cycles using n-pentane as the working fluid for low-grade waste heat recovery-to-power generation. Based on the thermodynamic and economic analyses, the feasibility analysis models of the cycles were established using Aspen Plus, considering efficiency, cost, and expected operating and capacity factors. Furthermore, the capacity factor, specific investment cost (SIC), and payback period (PBP), among other, were used to evaluate the cycle design configurations and sizes. The SICs of the simple and recuperative TLCs were 3,683.88 $/kW and 4,220.41 $/kW, and their PBPs were 8.43 years and 8.55 years, respectively. The simple TLC had a lower investment ratio of 0.24 compared to an investment ratio of 0.28 for the recuperative TLC. These economic values suggest that the simple TLC is more cost-effective when compared with the recuperative TLC because the recuperation process does not recompense the associated cost, making it unattractive.
H. A. Ajimotokan, A. A. Samuel, T. K. Ajiboye, T. S. Ogedengbe, and I. O. Alabi
African Journals Online (AJOL)
Due to the challenges associated with using crude oil-derived phenolic- or thermoplastics-based materials, agro-based composites have been used as alternative abrasive grains for abrasive tool manufacturing. This paper examines the morphology and physico-mechanical properties of resin-bonded palm kernel shell (PKS) and coconut shell (CNS) grain-based sandpaper composites and their wear performance. The PKS and CNS were collected, pulverised and screened into 250 and 500 μm grainsizes and mixed at ratios of 1:1, 1:2 and 2:1, respectively. Methyl-ethyl-ketone-peroxide and cobalt naphthalene of 1.5 wt. % each were utilised as hardener and catalyst, respectively for proper bonding of the aggregates with unsaturated polyester resin of compositions 12, 15, 18, 21 and 24 wt. %, respectively. To produce the sandpaper samples, the aggregates were compacted at a pressure of 15 MPa and the samples were cured and their morphology, mechanical, and wear properties were investigated.The shatter index, hardness, and compressive strength varied from 66.36% to 95.76%, 6.52 to 11.3 HRB, and 4.41 to 7.24 MPa, respectively. The wear resistance varied from 0.94 to 1.54 mg/m at 50 oC, and 1.02 to 2.09 mg/m at 150 oC. The properties of the aggregates made from PKS and CNS were found to have much influence on the performance parameters of sandpaper composites.
H. A. Ajimotokan, S. E. Ibitoye, J. K. Odusote, O. A. Adesoye, and P. O. Omoniyi
IOP Publishing
Abstract Densification of agricultural residues such as husks, shells and cobs into fuel briquettes is an alternative renewable feedstock for producing solid fuels because it improves their physico-mechanical, storage and combustion properties. This paper presents the physico-mechanical characterisation of fuel briquettes made from blends of corncob and rice husk. The raw samples of corncob and rice husk were collected, sorted and pulverised. The pulverised samples were screened to 0.25, 1.0 and 1.75 mm particle sizes, blended at mixing ratios of 80:20, 70:30, 60:40, and 50:50, and afterwards, briquette samples were produced at 25, 50, and 65 kPa compaction pressures respectively with starch as the binder. The variations in the particle size, mixing ratio and compaction pressure have significantly influenced the investigated physico-mechanical properties of the produced briquettes. The briquette made from 80:20 mixing ratio of corncob to rice husk, 0.25 mm particle size and 65 kPa compaction pressure had the highest compressive strength of 111 kN/m2 and the least compressive strength of 39 kN/m2 from briquette with 50:50 ratio of corncob to rice husk, 1.75 mm particle size and 25 kPa compaction pressure. The briquette made from 50:50 mixing ratio of corncob to rice husk, 0.25 mm particle size and 65 kPa compaction pressure spent the longest time to collapse when immersed in water; taking up to 972 seconds and the least time of 480 seconds from briquette with 80:20 mixing ratio corncob to rice husk, 1.75 mm particle size and 25 kPa compaction pressure.
H.A. Ajimotokan, A.O. Ehindero, K.S. Ajao, A.A. Adeleke, P.P. Ikubanni, and Y.L. Shuaib-Babata
Elsevier BV
H. A. Ajimotokan, S. E. Ibitoye, J. Odusote, O. Adesoye and P. Omoniyi
Densification of agricultural residues into briquettes as the alternative renewable feedstock can improve their physico-mechanical and storage properties as solid fuels. This paper presents the physico-mechanical properties of the composite briquettes made from corncob and rice husk. Raw samples of corncob and rice husk were collected, sorted and pulverised into fines of 0.25, 1.00 and 1.75 mm particle sizes. The fines were blended at mixing ratios of 80:20, 70:30, 60:40, and 50:50, bonded with 5% starch on weight percentage basis and compressed at compaction pressures of 25, 50, and 65 kPa to produce the briquette samples. The briquette made from 80:20 ratio of corncob to rice husk, 0.25 mm particle size and 65 kPa pressure exhibited the highest compressive strength of 111 kN/m2 and the least of 39 kN/m2 from briquette with 50:50 ratio of corncob to rice husk, 1.75 mm particle size and 25 kPa pressure. The briquette made from 50:50 ratio of corncob to rice husk, 0.25 mm particle size and 65 kPa pressure had the highest water resistance capacity, and the least from briquette of 80:20 ratio of corncob to rice husk, 1.75 mm particle size and 25 kPa pressure. The resulting physico-mechanical qualities of the produced corncob and rice husk briquettes suggested that they could be used as the solid fuels for domestic and industrial applications.
Habeeb A. Ajimotokan
Springer Science and Business Media LLC
H.A. Ajimotokan and I. Sher
Elsevier BV
Habeeb A. Ajimotokan, Ilai Sher, Chechet Biliyok, and Hoi Yeung
Elsevier
Habeeb Adewale Ajimotokan
Emerald
Purpose – The purpose of this paper is to employ a system dynamics approach to develop a mathematical model for managing magnitude and risk factors of injuries in a manufacturing industry. This is to provide the decision makers with a systemic‐strategy to capture the transition of industries, especially manufacturing, into world‐class safe workplaces.Design/methodology/approach – An accident investigation register was administered to capture needed data to estimate the model parameters and identify risk factors of injuries. The principle of system dynamics (SD) was employed to identify the relevant safety‐related components and their interrelationships. Applying the concept of causality analysis, causal loop and SD flow diagrams indicating how prevention activities may eliminate hazardous conditions were delineated and a mathematical model to predict the main variables involved in manufacturing safety programme was formulated.Findings – The validity of the model was demonstrated using the observed data fr...
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...
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.