Mathematical modelling of stalk biomass shredding process
2019
Nulle, I., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Kakitis, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Smits, M., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Vronskis, O., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
In Latvia, approximately 14.6 % of unfarmed agricultural land can be used for herbaceous energy crop growing. Herbaceous energy crops would be the main basis for solid biofuel production in the agricultural ecosystem in future. There is a possibility to utilize for bioenergy production natural biomass of common reeds (Phragmites australis), overgrowing the shorelines of Latvian more than 2000 lakes. Common reed stalk material ultimate tensile strength average value was stated 330 ± 29 N⋅mmE−2. This value testifies that common reeds are the strongest material among other energy crop stalk materials. The main conditioning operation before preparation of herbaceous biomass compositions for solid biofuel production is shredding. In the previous experiments it was stated that cutting energy depends on the cutting knife angles against the shear bar, layer thickness of the material and the shape of the knives. It is important to designate the significance of these parameters to biomass shredder design. In the article a mathematical model of the stalk biomass cutting process is described, which evaluates the energy consumption dependence on the angle between the knife and the shear bar, distance of the knife from the rotor centre and thickness of the cutting layer. The model includes the peculiarities of the shredder rotor design, which determines the regularity of the angle of the knife angle relative to the counter cutter, depending on the rotor rotation angle. The obtained results will allow to determine the most suitable positioning of the knives on the rotor, ensuring smooth torque in the cutting process.
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