RHEOLOGICAL PROPERTIES OF SLURRY FUELS

The rheological properties of four slurry fuels were studied and a variety of complex flow phenomena was observed. The slurry fuels contained ca. 50% by weight carbon black particles with an average particle size of 0. 1 mu m. Most of slurries had a yield stress ranging from 2 to 110 dyn/cm**2. For the slurries which had a large yield stress, stress overshoot was observed. The stress overshoot increased with increasing shear rate. The maximum stress overshoot occurred at lower shear strains, the higher the shear rate. A preliminary analysis was developed by using a modification of our kinetic-elastic theory to describe the pseudoplastic and thixotropic behaviors of materials that exhibit a yield stress. The temperature effect on viscosity was also analyzed in terms of this model.