High-pressure viscosities of fatty acid esters and biodiesels from a new thermodynamic model

Document Type : Research Article


1 3Department of Chemistry, Shiraz University of Technology, Shiraz, Iran

2 Chemistry department, Shiraz University of technology, Shiraz, Iran


This work deals with the modeling of dynamic viscosities of several fatty acid esters (FAEs) and biodiesels based on the friction theory (FT) along with a perturbed hard-dimer-chain equation of state (PHDC EOS). The model used three molecular parameters (e, s, m) and liquid density as well, all of which were estimated from the PHDC EOS. The PHDC EOS could predict the density and isothermal compressibility coefficients in 278.15-393.15 K range and pressures up to 210 MPa with the average absolute relative deviations (AARDs) of 0.52% and 4.77%, respectively. Then, the proposed FT-based model has been employed for predicting the dynamic viscosities of several FAEs and biodiesels in 293.15-393.15 K and pressures up to 200 MPa. The model predicted 892 experimental data points for dynamic viscosities of 10 FAEs and 3 biodiesels with the AARD of 1.70%. Further, the degree of accuracy of proposed model has also been compared with some semi-theoretical and empirical approaches. Our comparison results revealed the superiority of the proposed model against the literature approaches.


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