Browsing by Author "Ojolo, S.J."

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    Mathematical modelling of die pressure of a screw briquetting machine
    (Journal of King Saud University - Engineering Sciences, 2020-12-01) Orisaleye, J.I.; Ojolo, S.J.; Ajiboye, J.S.
    The screw briquetting machine has problems which have been attributed to poor design. There are limited theoretical studies targeted at solving problems of biomass briquetting machines. The briquetting die determines the final shape and quality of the biomass briquettes. The performance of the screw briquet- ting machine is also dependent on the design of the briquetting die. In this paper, mathematical models were developed to study the die pressure using a plug flow theory. Effects of die entry angle, die reduction ratio, length of briquetting die, biomass compact yield strength and friction on the die pressure were investigated using the models. Increasing the die entry angle, reduction ratio, compact yield strength and friction coefficient resulted in increase in the die pressure. Increase in length of briquetting die and friction coefficient also resulted in increase in the die pressure. Optimum die entry angle was dependent on the yield strength of compacted material and the friction coefficient at the interface between the die and the compacted material. This study is useful in developing improved screw briquetting machines.
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    Plug flow analysis for the design of the compaction region of a tapered screw extruder biomas briquetting machine
    (Agricultural Engineering International: CIGR Journal, 2015-09-01) Ojolo, S.J.; Ajiboye, J.S.; Orisaleye, J.I.
    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 coefficient of the biomass material with enclosing surfaces and ranges between 2 and 4.
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    Pressure build-up and wear analysis of tapered screw extruder biomass briquetting machines
    (CIGR Journal Open access, 2019-01-01) Orisaleye, J.I; Ojolo, S.J.; Ajiboye, J.S.
    The design of efficient screw extruder biomass briquetting machines is important for the utilization of loose biomass materials from wood and agricultura l 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-up along the screw extruder biomass briquetting machine. The geometrical and operational parameters which resulted in rapid pressure build-up required shorter screw length for the briquetting machine. The wear model developed predicted the screw wear satisfactorily and showed that the screw speed and the choice of material for screw affected the screw wear. The wear volume increased exponentially towards the end of the screw where pressure is the highest. Redesigning the screw to select optimum geometry and speed with appropriate choice of material could improve the screw life and performance of the biomass briquetting machine.