Mathematical models for prediction of rheological parameters in vinasses derived from sugar cane
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| Authors: | L. Chacua1, G. Ayala2, H. Rojas1, A. Agudelo1 1Faculty of Engineering and Administration, National University of Colombia, Palmira campus, AA 237, Colombia 2Faculty of Animal Science and Food Engineering, University of São Paulo, Av. Duque de Caxias Norte 225, 13635-000, Pirassununga, SP, Brazil |
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| Abstract : | 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 (R2 = 0.951), showing that the soluble solids content and temperature have an opposite effect on consistency coefficient values. |
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| Keywords : | ethanol industry, vinasses, pseudoplastic, rheological models | ||||||||||
| Language : | English | ||||||||||