Sunday Ojolo

University Of Lagos Akoka, Mechanical Engineering, Faculty Member

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I am an Associate Professor of Machinery Design and Manufacturing Engineering at Department of Mechanical Engineering, University of Lagos, Nigeria.

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Papers by Sunday Ojolo

Development of an inverted downdraft biomass gasifier cookstove

Journal of Emerging Trends in Engineering and Applied Sciences, 2012

About eighty percent of Nigerians and sixty percent of Africans live in rural communities most of... more About eighty percent of Nigerians and sixty percent of Africans live in rural communities most of who utilize biomass for cooking. The benefits of improved cookstoves coupled with the perennial fuel crisis have led to intensified research into the development of the biomass cookstoves. This work aims to develop a biomass cookstove for use in developing countries. The biomass cookstove working with an inverted downdraft gasifier was developed and evaluated at Lagos State University, Nigeria. The biomass used was wood shavings with bulk density of about 0.05 g/cm3 and with a moisture content of about 19.2% on dry basis and 16.2% on wet basis. The fuel conversion rate is 1.89 kg/h and it has a thermal effeciency of about 10.6%. The heating rate of the biomass cookstove was higher than the kerosene stove but less than the electric stove. While further work on the cookstove is recommended and proposed, the present and subsequent works can be adapted to suit rural applications where bioma...

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Ergonomic evaluation of cashew nut shelling machine

Agricultural Engineering International: The CIGR Journal, 2016

This paper presents the ergonomic evaluation of a manually operated village-level cashew nut shel... more This paper presents the ergonomic evaluation of a manually operated village-level cashew nut shelling machine. A manually operated cashew nut cracking machine was evaluated. Fifty subjects took part in the study, with physiological, postural, and subjective measurements being taken. Comfort Questionnaire for cashew nut cracking machine (CQC) was also evaluated. Using the machine resulted in postural discomfort. The perception of the subjects as per the efficiency of the machine was neutral; 50% accepted that the machine is efficient, while the other 50% were unsatisfied. Following a participatory ergonomic process and using appropriate anthropometric measurements, an improved, adjustable prototype was developed. The lever arm was designed based on 5th percentile of the subjects; blades were welded into the cracking lid to reduce the amount of impact force used for cracking, so as to reduce crushing of the nuts. Also the ergonomic seat and worktable allow posture change from sitting ...

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Investigation on Induced-Residual Stress During End Milling Operation Using Analytical Modelling

Design and development of waste sorting machine

Journal of Emerging Trends in Engineering and Applied Sciences, 2011

Nigeria is yet to develop a comprehensive scheme which is required to solve the current and persi... more Nigeria is yet to develop a comprehensive scheme which is required to solve the current and persisting problem of waste management in the country. Whereas the crude methods of sorting wastes practiced may be efficient, it wastes useful time; hence the need for a mechanized sorting machine. An attempt has been made to develop a waste sorting machine, which is conceptualized to sort wastes into light materials, ferrous metals and other heavy materials. The machine is designed with the major components being the fan, the belt conveyor and the magnet. Tests carried out on the machine successfully classified wastes into light materials and heavy materials with inability to sort ferrous metals. Samples of wastes tested weighed 1.15kg and 3.53kg. The wastes consisted of an average of 32% of light materials and the time to sort the waste was 65 minutes per unit mass. This machine separates light materials such as paper, nylon, textile and heavy materials similar to nylon, ferrous and non fe...

Design of a Jathropha oil expelling machine

Journal of Emerging Trends in Engineering and Applied Sciences, 2012

Biodiesel is a fuel type that has already been proven suitable for use in diesel engines. The non... more Biodiesel is a fuel type that has already been proven suitable for use in diesel engines. The non-edible vegetable oil of Jatropha curcas, which grows in tropical and subtropical climates across the developing world, promises a commercially viable alternative to diesel. Jatropha oil is renewable, environmental friendly and can be easily produced in rural areas. This paper presents the design of an efficient Jatropha oil expelling machine carried out at the University of Lagos, Nigeria. The design of this Jatropha oil expelling machine will enhance the production of biodiesel from Jatropha seeds. The designs of the crushing system and pre-heating systems before pressing will enable the machine operate at efficiency greater than 90%. This machine is easy to maintain and economic for commercial uses. The Jatropha oil expelling machine has been designed to a capacity of 1000 kg/hr and can expel oil at the rate of 2.2 m 3 /hr. The machine is powered using electric motor of 40kW to be operated for 8 working hours. This machine is an improvement over existing machine and presupposes appropriate technology for manufacture, operation and maintenance. __________________________________________________________________________________________

Plug Flow Analysis for the Design of the Compaction Region of a Tapered Screw Extruder Biomass Briquetting Machine

Agricultural Engineering International: The CIGR Journal, 2015

The study of compaction or solids conveying in a screw extruder has been carried out majorly on t... more The study of compaction or solids conveying in a screw extruder has been carried out majorly on the straight screws using the plug flow analysis. Despite this, the analysis of the straight screw appears to be complex as contained in existing literatures based on the force and torque balance. The tapered screw, which is considered to be an effective option for biomass compaction, introduces greater complications because the geometry is constantly changing. In this study, a method based on the traction and retardation mechanism of friction is developed for a fully unwound screw channel utilizing only the force balances. The procedure has been used to carry out a parametric analysis of the tapered screw extruder for a screw press biomass briquetting machine. The taper angle was considered to significantly increase the pressure developed in the extruder depending on the length of the compaction zone. The optimum taper angle has also been found to be dependent on the frictional coefficie...

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Theoretical Determination of Temperature Field in Orthogonal Machining

International Journal of Engineering and Technology Innovation, 2013

In this work, mathematical models were developed to simulate the thermal behaviour of a cutting t... more In this work, mathematical models were developed to simulate the thermal behaviour of a cutting tool insert in three-dimensional dry machining. Models to determine the temperature rise at the shear plane and tool insert in orthogonal cutting were developed, simulated and validated. The effects of various machining parameters/variables such as specific heat of material of 4400J/kg, Depth of cut (t) of 0.0003m, Density of 7870kg/m3, Width of cut (b) of 0.005m, Chip thickness ratio (rt) of 0.42, Tool rake angle of 100, Cutting Velocity (V) of 35m/min and Shear force (Fs) of 1257.6N on temperature rise were well analyzed.

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Development of a Variable Size Nut Cracker

In this work, a variable size nut cracking machine has been designed and constructed to improve t... more In this work, a variable size nut cracking machine has been designed and constructed to improve the efficiency of shelling operation of quite a number of nuts. The machine is designed to be adaptable to the cracking requirements of some number of nuts, whose shell can be processed to brittleness. The machine performs two operation s , shelling of the nut and separation of the shell from the nut. The machine comprises of a hopper, rectangular box housing the cracking drum and compression plate, and a two stage agitated separating tray (to sort the nut from the shell), all supported by a frame. The cracking drum, which is driven by a v-belt connected to an electric motor, also provide the agitation to the separating tray via a v-belt connected a cam mounted shaft that helps push the tray against stationary springs to return the tray to its initial position upon the dwell of the cam. The continual return and compression of the tray against the spring subjects the tray to a vibration ne...

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Design and Fabrication of a Yam Peeling Machine

The Journal of Engineering Research, 2017

Yam, Dioscorea sp., is an important root crop in the tropics which can be processed into a wide v... more Yam, Dioscorea sp., is an important root crop in the tropics which can be processed into a wide variety of forms for consumption as food. However, peeling is an important process which increases the value of processed food. Yam peeling machines need to be developed for this purpose which had been carried out manually with the use of knives and on a domestic scale. A yam peeling machine which has a dual operation was developed in this study. The machine utilizes spring-loaded peeling knives and power screw mechanics during peeling operations. The machine was evaluated for performance and the peeling efficiency ranged between 71.2 and 100%. The peeling rate was 11.15 mm/s during motorized operation and 3.45 mm/s during manual operation. The peeling loss ranged from 3.67 to 14.29% during motorized operation and from 3.91 to 16.96% when the machine was operated manually. The machine can be developed for small scale food industries at reasonable cost and minimal maintenance. Keywords: Ya...

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Design of an office table solar-DC powered fan

A table fan is a small, portable type of fan that is used in various rooms of a home or office. I... more A table fan is a small, portable type of fan that is used in various rooms of a home or office. It is more convenient compared to other types, like kitchen exhaust, window, and pedestal fans because of its portability. It serves a number of functions for home owners and office workers such as conservation of energy compared to using air conditioners, removal of heat and unwanted fumes from indoor areas, cooling a room and generation of mechanical noise that helps to distract a person's attention from undesirable background noise so he could focus on his task. The idea of a solar fan has been proven to be a very good especially for a country like Nigeria that enjoys an average of 8 hours of sunlight daily. The same sun that causes heat is made to power an object of thermal comfort at a low level of sophistication. In this design, a 3-blade table fan of 25 watt capacity capable of 6 hours of continuous operation was powered with just 1.0 Photo-voltaic (PV) module of 80 watt power ...

Design and Development of a Laboratory Scale Biomass Gasifier

A laboratory scale downdraft biomass gasifier was designed to deliver a mechanical power of 4 kW ... more A laboratory scale downdraft biomass gasifier was designed to deliver a mechanical power of 4 kW and thermal power of about 15 kW. The gasifier was manufactured as a single piece having a water seal and cover. The gasifier was tested in natural downdraft and forced downdraft mode. Ignition of the fuel beneath the grate, during natural downdraft mode, using wood shavings as fuel, produced gas which burned with a blue flame for 15 minutes. Ignition at the throat, using either palm kernel shells or wood shavings, during the natural downdraft mode, the gasifier did not produce syngas. During the forced downdraft mode, fuel was ignited at the throat. Gasification was successful with the palm kernel shells, during forced downdraft, which produced gas which burned steadily with luminous flame for 15 minutes per kilogram of biomass fed. However, wood shavings experienced some bridging problems during the forced downdraft mode of operation. The fuel conversion rate of the gasifier, when usin...

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Mathematical Modelling of Leachate Production from Waste Contained Site

In this work, mathematical models of leachate production from Waste Contained Site (WCS) was deve... more In this work, mathematical models of leachate production from Waste Contained Site (WCS) was developed and validated using the existing experimental data with aid of MATLAB, 2007a. When the leachate generation potentials (Lo) were 100m3, 80m3 and 50m3, the maximum amount of leachate generated were about 2920m3, 2338m3 and 1461m3 for about 130 days respectively. It was noted that as the leachate percolates through a selected distance, the concentration keeps decreasing for one dimensional flow in all the cases considered. Decreasing in concentration continues until a point was reached when the concentration was almost zero and later constant. The effects of diffusivity, amount of organic content present within the waste and gravity, as cases, were also considered in various occasions during the percolation. Comparison of their effects was also taken into account. In case of gravity at constant diffusivity, decrease in concentration was not rapid but gradually while much organic conte...

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Pressure build-up and wear analysis of tapered screw extruder biomass briquetting machines

Agricultural Engineering International: The CIGR Journal, 2019

The design of efficient screw extruder biomass briquetting machines is important for the utilizat... more The design of efficient screw extruder biomass briquetting machines is important for the utilization of loose biomass materials from wood and agricultural wastes for the production of solid fuel. In this study, the effects of geometrical parameters (channel depth and helix angle) and operational parameters (friction coefficient, mass flow rate and speed) on the performance and design of the briquetting machine were investigated using a pressure model based on the plug flow theory. An analytical model, which utilizes the pressure model, was also developed from Archard’s wear law to investigate screw wear of biomass briquetting machines. The study on the pressure model showed that a shallow screw channel and small helix angle resulted in rapid pressure build-up along the screw extruder biomass briquetting machine. High friction at the barrel-material interface, low friction at the screw-material interface, high screw speed and high mass flow rate also resulted in rapid pressure build-...

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Design and Development of an Improved Palm Kernel Shelling Machine and Separator

Physical Science International Journal, 2017

A palm kernel processing (Cracking and Separating) unit was developed to crack effectively variou... more A palm kernel processing (Cracking and Separating) unit was developed to crack effectively various sizes/diameters of palm kernel as well as to separate the palm kernel from the shell with the aim of reducing the challenges encountered during the production of palm kernel Oil. This machine was fabricated and designed with locally available materials for the ease of maintenance and it was designed the the aims of easing the pain, stress involved, intensive labour, time consuming, unduly cost and cumbersome operation encountered in the traditional/existing process of manually cracking and separating palm kernel from the nut. After the fabrication of this machine, the machine was tested to ascertain its performance and efficiency. The efficiency of the machine was discovered to be 98% with a processing rate of 95 nuts per second. This is an improvement over existing ordinary palm kernel machine that has an efficiency of 90% with a processing rate of 87 nuts per second wiithout separation. A 5 hp Prime mover was selcted based on the power that was needed to effectively operate the machine. This project has catered for the various challenges encountered in the manual process of shelling palm kernel and separating the kernel from the shell.

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Kinetic Modeling and Simulation of Pyrolysis of Shrinking BiomassParticle in Fixed Bed Gasifier

iranica journal of energy and environment, 2016

Shrinking biomass particle Pyrolysis kinetics Isothermal condition Non-isothermal heating

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A survey on the effects of vehicle emissions on human health in Nigeria

Vehicular emissions generally include oxides of nitrogen, sulphur, carbon hydrocarbon, mercury an... more Vehicular emissions generally include oxides of nitrogen, sulphur, carbon hydrocarbon, mercury and leads. The effects of vehicular emissions on human health, vegetations, and environments were investigated in three locations of Lagos (Oshodi, Mushin and Apapa), Nigeria while a fourth location (Fola Agoro) was used as a control since it has low levels of pollution. The investigation was carried out with the use of questionnaires and laboratory experiments. Experiments were conducted on rainwater collected from each location to determine the level of acidity, pH, and the presence of dissolved substances such as NO3, SO4 and CO2 in them. Physical effects on vegetations, buildings and structures were also observed. The results obtained from questionnaire show that on the average, 28.3%, 16.6%, 23.3%, 18.3%, 13.3% were respectively affected by sleeplessness, running nose, heavy eyes, asthmatic attack, and headache respectively. The location (distance from the coast type of fuel, availabi...

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Study of rake face action on cutting using palm-kernel oil as lubricant

The work investigates the effect of cutting speed, feed rate, depth of cut, and rake angle on mai... more The work investigates the effect of cutting speed, feed rate, depth of cut, and rake angle on main cutting force during the cylindrical turning of mild steel, brass, and aluminum rod, using high speed steel cutting tool and palm-kernel oil as cutting fluid. The impact of lubrication on the coefficient of friction between the chip and rake face during turning operation, assuming a negligible friction between the flank and cut surface is measured. Experimental results show that aluminum at cutting speed of 4.15m/s and rake angle 9 o gave a 33.3% reduction in coefficient of friction while brass and mild steel under the same cutting condition gave7.9 and 13.8% increase in coefficient of friction respectively. Findings at cutting speed of 4.15m/s and depth of cut 1.5mm gave 9.79% reduction, 46.7 and 20.8% increase in coefficient of friction for brass, aluminum and mild steel respectively while cutting speed of 4.15m/s and feed 1.8mm/rev gave a 9.2% reduction, 30.4 and 14.5% increase in coefficient of friction for brass, aluminum and mild steel respectively. Similar trend was observed by varying the cutting conditions on the workparts through different selected values. The effect of palm-kernel oil as a metal cutting lubricant is more pronounced on aluminum than brass and mild steel. __________________________________________________________________________________________ Keywords: cutting speed, feed rate, depth of cut, palm-kernel oil, lubricant __________________________________________________________________________________________ I TRODUCTIO Metal cutting or machining produces desired shape, size, and surface finish through the removal of chip from a rough block of material . Since chip formation is the heart of metal cutting, adequate understanding of the chip-forming process is needed if improvement and better utilization of machining is to be achieved. Cutting is accomplished through a joint action of cutting force and normal force and since there is no movement in the normal direction, the entire power is consumed by the cutting force to overcome frictions and to break down metal bonds. The work piece is deformed plastically in shear zone during metal cutting, and it is removed from the region as chips. The energy required for the deformation is converted into heat which is usually dissipated away through the workpiece, cutting tool, chips and the cutting fluid. According to , approximately 60% heat is generated in the shear region of the workpiece and 80% of this heat goes into the chips, hence a properly applied cutting fluid at the cutting zone absorbs the heat away, hence, temperature in machining depends upon the balance between the rate at which heat is generated and the rate it is dissipated .

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Computer Aided Analysis of Thermal and Mechanical Design of Shell and Tube Heat Exchangers

Advanced Materials Research, 2011

Most of the attempts made at designing shell and tube heat exchangers have been limited to therma... more Most of the attempts made at designing shell and tube heat exchangers have been limited to thermal hydraulic design. This study however, considers both the thermal and mechanical design of the E-type shell and tube heat exchanger with the aid of computer programming. It involves developing a simple user-friendly computer programme for the heat transfer calculations and ensures that the computational time is kept minimal. The algorithm is designed such that after the conditions for the thermal analysis are satisfied, the programme automatically proceeds to the mechanical design. The programme written in Visual Basic was tested using a model and the simulated result presented.

Comparative Study of Biogas Production from Five Substrates

Advanced Materials Research, 2007

In this work, a comparative study of biogas production from poultry droppings, cattle dung, kitch... more In this work, a comparative study of biogas production from poultry droppings, cattle dung, kitchen waste, fruit waste and vegetable waste was done under the same operating conditions. 3kg of each waste was mixed with 9kg of water and loaded into the 5 constructed digesters. Biogas production was measured using water displacement method for a period of 40 days and at an average temperature of 30.5oC. Results indicated that poultry droppings produced 0.0332dm3/day, cow dung produced 0.0238dm3/day, Kitchen waste produced 0.0080dm3/day, vegetable waste produced 0.0066dm3/day and fruit waste with 0.0022dm3/day. It is concluded that poultry droppings produced more biogas because it contains more nutrients and nitrogen compared with plant and other animal waste

Experimental determination of the effect of some straight biological oils on cutting force during cylindrical turning

Matéria (Rio de Janeiro), 2008

Cutting fluids of various types are usually employed to control the heat generated in machining. ... more Cutting fluids of various types are usually employed to control the heat generated in machining. The continued application of conventional petroleum based metal working fluids is being challenged by the need to reduce overall volume of fluids, minimize health risks and bio-contamination. Bio-oils assisted machining is an environmental bio-compatible technology for desirable control of temperature. This paper investigates the effect of some vegetable based oils on cutting force during cylindrical machining of mild steel, aluminium and copper. The results indicated that bio oils are suitable for metal working fluids but the effects of the bio-oils on cutting force are material dependent. Groundnut oil exhibited the highest reduction in cutting force when aluminium was being turned at a speed of 8.25m/min and feeds of 0.10, 0.15 and 0.20mm/rev, respectively. Palm kernel oil had the best result when copper was turned at feeds lower than 0.15 mm/rev. However, at higher feeds, groundnut oil had the best result for copper. Coconut oil recorded the highest cutting force in all the three materials machined followed by shear butter and as such are very mild in reducing cutting force during cylindrical machining. It is concluded that groundnut and palm kernel oils are effective in reducing cutting force during cylindrical turning. Though, the lubricating and cooling action is material dependent, groundnut oil is the best among the four bio-oils investigated.

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