Frictional behaviour of wheat straw-water suspensions in vertical upward flows

The use of biofuels helps mitigate greenhouse gas emissions. Earlier studies have shown that transporting biomass in horizontal pipelines in the form of water-based slurries significantly reduces transportation costs. The frictional behaviour of water-based chopped wheat straw slurry in a vertical pipeline has not been studied and this is the focus of this study. In situ concentrations of water-based conventional solids of medium sand, glass beads, and fine sand and straw slurry flows were determined by measuring their delivered concentrations in pseudo-homogeneous regimes for prepared concentrations of 1-6% (dry volume of conventional solids) and 5-25% (saturated mass of straw), respectively. Two grades of sand and glass beads with mean particle diameters of 0.103, 0.447, and 0.5 mm, respectively, and straw with a nominal particle length of 19.2 mm were utilised. The delivered concentrations for the straw slurries and fine sand were close to their corresponding prepared concentrations and were homogeneous. There was a large discrepancy between prepared and delivered concentrations for the medium-sized sand and glass beads slurries. The pressure drop of straw slurries over the range of velocities of 0.5-4.2 m s(-1) and mass concentrations of 5-25% through the vertical pipe showed a maximum drag reduction of 19% at a concentration of 25% (mass) and at a 3.5 m s(-1) velocity. For concentrations of 5-20% (mass), the straw slurries showed drag-reducing capabilities in the mixed and turbulent flow regions for various velocities that were different from horizontal flows. (C) 2021 IAgrE. Published by Elsevier Ltd. All rights reserved.

Automated summary

The use of biofuels can help reduce greenhouse gas emissions, and studies have shown that transporting biomass in the form of water-based slurries through horizontal pipelines can significantly lower transportation costs. This study focuses on the frictional behavior of water-based chopped wheat straw slurry in a vertical pipeline, and found that the delivered concentrations for straw slurries and fine sand were close to their prepared concentrations, while there was a large discrepancy for medium-sized sand and glass beads slurries. Additionally, straw slurries showed drag-reducing capabilities in the mixed and turbulent flow regions at different velocities compared to horizontal flows.