Department of Mechanical Engineering

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Browsing Department of Mechanical Engineering by Subject "Biomass densification"

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    Open Access
    Mathematical modelling of pressure distribution along the die of a biomass briquetting machine
    (Inderscience Enterprises Ltd., 2019-12-15) Ojolo, S.; Orisaleye, J.
    The screw extruder briquetting die is critical to determining the quality of biomass briquettes. In this study, mathematical models were developed to study pressure distribution along the briquetting die using the hot extrusion scheme and assuming a plug flow. Parametric analysis to determine the effects of design variables on die pressure distribution was carried out by simulation using developed mathematical models. Results showed that pressure along the die entry decreases rapidly with high yield strength of compacted biomass and with increased friction coefficient at the briquetting die interface. As friction coefficient at the die interface increases, there is rapid decrease in pressure along the length of the die. Parameters resulting in rapid pressure decrease along the briquetting die length would result in increased die pressure at the end of the screw extruder. The developed mathematical models and the results obtained could significantly contribute to design of briquetting dies.
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    Parametric analysis and design of straight screw extruder for solids compaction
    (Elsevier B.V., 2017-03-30) Orisaleye, J.I.; Ojolo, S.J.
    Screw extruders are commonly used in the food and polymer industries. Scientifically designed screw extruders for biomass compaction equipment are required to limit the existing problems faced in the industry. In this study, models based on the plug flow theory were developed and used to analyse the screw extruder for biomass compaction. The approach for development of the plug flow model involves a traction-and-retardation based mechanism utilizing force balances only, in contrast to the force and torque balance of previous models. The pressure developed along the length of the screw extruder was exponential and affected by the friction coefficients at biomass material interfaces between the screw and barrel, the channel depth and helix angle. The movement of material in the compaction region is drag-induced and the screw speed, channel depth and helix angle determine the flow rate through the screw channel. The approach utilized in this study for the development of models could be extended to study other types of screw extruders with relative ease compared to earlier approaches based on the plug flow theory.