Mathematical models for prediction of rheological parameters in vinasses derived from sugar cane

Abstract

A b s t r a c t. The rheological behaviour of vinasses derived from sugar cane was studied as a function of time (0 and 600 s), soluble solids content (44 and 60 °Brix), temperature (10 and 50°C), and shear rate (0.33 and 1.0 s -1 ). The results indicated that vinasses were time-independent at 25°C, where shear stress values ranged between 0.01 and 0.08 Pa. Flow curves showed a shear-thinning rheological behaviour in vinasses with a flow behaviour index between 0.69 and 0.89, for temperature between 10 and 20°C. With increasing temperature, the flow behaviour index was modified, reaching values close to 1.0. The Arrhenius model described well the thermal activation of shear stress and the consistency coefficient as a function of temperature. Activation energy from the Arrhenius model ranged between 31 and 45 kJ mol -1 . Finally, the consistency coefficient as a function of the soluble solids content and temperature was well fitted using an exponential model (R 2 = 0.951), showing that the soluble solids content and temperature have an opposite effect on consistency coefficient values.

A Review on the Rheological Behavior of Organic Waste for CFD Modeling of Flows in Anaerobic Reactors

“…The power-law model parameters (consistency index and power-law index) are presented in the Table 3. In contrast to the previous study [35], the consistency index and the power-law index increase with the increase of temperature [53]. At 40°C, the temperature closest to the mesophilic regime, the power-law index is 1.01, characterizing Newtonian behavior.…”

“…In a study conducted by Chacua et al (2016), it has been shown that vinasse has a pseudoplastic behavior for temperatures between 10 and 20 °C [53]. Indeed, when the temperature is superior to 30 °C, the power-law index is close to 1, indicating an approach to the Newtonian model [53].…”