Characterization of the viscosity of bio-oil produced by fast pyrolysis of the wheat straw

The aim of this work is to evaluate the role of viscosity of the organic condensate obtained from fast pyrolysis of wheat straw. Based on the experimental data, a model has been developed that is able to adequately describe the viscosity as a function of relevant process parameters. The developed model is helpful to investigate the reduction of heat transfer in the heat exchangers of the organic condensate cycle when glycol is replaced by an organic condensate. Temperature, solid contents, and water contents play a significant role and affect the viscosity of bio-oil. As temperature increases, the viscosity of oil reduces rapidly. Viscosity-temperature profile follows an Arrhenius-type-relationship, where the viscosity of the bio-oil decreases exponentially with increasing temperature. As solid content increases, exponential increase of viscosity takes place. However, the increase in water content results in decrease of viscosity on logarithmic scale. The range of water addition in organic condensate is possible up to a certain limit, after certain limit it starts to separate out in two phases. Investigation of reduction of heat transfer in heat exchanger shows that Nusselt number decreases with the increase of viscosity. Therefore, the overall heat transfer coefficient will decrease in case of organic condensate as compared to glycol.