Supplemental information for "Experimental Study on Two-Phase (Solid-Liquid) Flows of Ground Wheat Straw in Inclined Pipes"

Long-distance pipeline hydro-transport of lignocellulosic biomass for industrial-scale biofuel production at levels comparable to conventional oil refineries presents an economically and logistically viable alternative to fossil fuels. There is very limited understanding on the behavior of the transportation of agricultural biomass slurries in an inclined pipeline. This research is focused on a laboratory-scale investigation of 6.4 mm nominal particle length ( = 4.85 mm) knife-milled wheat straw-water suspensions' uphill and downhill flows for a range of pipe inclination and saturated mass concentrations. The range of pipe inclination and saturated mass concentration was -7 degrees to +21 degrees and 5%-30%, respectively. The inclined test section was 29 m long with a 50 mm inside diameter of a closed pipeline loop. The accuracy of the measurements was verified by calibrating the inclined pipe section with fine sand-aqueous slurries and comparing the results with established correlations. Most wheat straw-aqueous suspensions in the inclined flows showed the characteristics of the plug flow and the transition flow regions together for saturated mass concentration of 5%-30% and the entire flow range (0.5-4.7 m/s) with a clear dependence of both onset velocity of drag reduction and drag reduction (%DR) on the pipe inclination as well as slurry concentration and the critical concentration of maximum drag reduction on a specific range of suspension velocity. Because of the accelerating effect of gravity, downhill slurry flows had the lowest onset velocity of drag reduction and the highest %DR at every and pipe inclination. Uphill flows demonstrated some nonmonotonic changes in onset velocity of drag reduction and %DR, which need more experimental data for us to reach a firm conclusion. The research outcomes could help design and operate a long-distance integrated pipeline network for biomass transportation to produce biofuels on large scale.