Rheological study of black coal-oil suspensions

The rheological study of coal-oil suspensions is very important because of their application in many industries as alternative fuels to petroleum oil. In this work, the flow behaviour of black coal-oil suspension was studied for a range of coal volume fractions from 0.0378 to 0.427. Shear stresses were measured for shear rates up to 200 s^–1 using a Weissenberg Rheogoniometer. All the suspensions behaved like non-Newtonian liquids and exhibited significant increases in apparent viscosity on storage. The flow behaviour of both freshly prepared and aged suspensions was able to be described by power-law models. A model similar to that given by Chong was used to establish relation between the relative apparent viscosity and coal volume fraction for freshly prepared as well as all aged suspensions. A correlation was also established between ageing time and maximum coal volume fraction.a constant in eq. (9) - A, B constants - K consistency index, Pa s^–n - n power-law index - S structure - t time, hrs - µ_a apparent viscosity, Pa s - µ_r relative viscosity - volume fraction - _m maximum volume fraction - shear stress, Pa - sus suspension - sol solvent - standard deviation