The viscosity of four aged bio-oil samples was measured experimentally at various shear rates and temperatures using a rotational viscometer. The experimental bio-oils were derived from fast pyrolysis of beech wood at 450, 500, and 550 °C and Miscanthus at 500 °C (in this work, they were named as BW1, BW2, BW3, and MXG) in a bubbling fluidized bed reactor. The viscosity of all bio-oils was kept constant at various shear rates at the same temperature, which indicated that they were Newtonian fluids. The viscosity of bio-oils was strongly dependent upon the temperature, and with the increase of the temperature from 30 to 80 °C, the viscosity of BW1, BW2, BW3, and MXG decreased by 90.7, 93.3, 92.6, and 90.2%, respectively. The Arrhenius viscosity model, which has been commonly used to represent the temperature dependence of the viscosity of many fluids, did not fit the viscosity-temperature experimental data of all bio-oils very well, especially in the low- and high-temperature regions. For comparison, the Williams-Landel-Ferry (WLF) model was also used. The results showed that the WLF model gave a very good description of the viscosity-temperature relationship of each bio-oil with very small residuals and the BW3 bio-oil had the strongest viscosity-temperature dependence.
Bibliographical noteThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy and Fuels, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.energyfuels.6b00640
Funding: International Research Staff Exchange Scheme (IRSES) ECOFUEL programme (FP7-PEOPLE-2009-IRSES Grant 246772). Scott W. Banks and Tony Bridgwater acknowledge the collaboration and funding through the Engineering and Physical Sciences Research Council (EPSRC) Grant (EP/K036548/1)“ Development of Fast Pyrolysis Based Advanced Biofuel Technologies for Biofuels”