A comparative study between Helmholtz and entropy scaling approaches for viscosity of natural gas mixtures based on the GERG-2008 equation of state

THERAN-BECERRA, OSCAR I.; BENELLI, FEDERICO E.; CISMONDI-DUARTE, MARTÍN

FLUID PHASE EQUILIBRIA

ELSEVIER SCIENCE BV

Año: 2023 vol. 574

0378-3812

This study scaling approach, the residual entropy scaling approach, andthe modified entropy scaling approach proposed by Bell for predicting theviscosities of pure n-alkanes, as well as other light compounds, and naturalgas mixtures at different pressure and temperature conditions.The modified entropy scalingapproach showed the lowest global average absolute deviation (AAD) for purecomponents, with a value of 2.37%. In comparison, the Helmholtz scaling approachhad a slightly higher value of 2.70%, while the entropy scaling approachproduced the highest value at 4.02%. The predictive performance of different mixingrules was evaluated for a strongly asymmetric binary system(methane + n-decane), across a broad range of compositions, pressures, andtemperatures. For all-natural gas mixtures, excellentresults were achieved with similar AAD values obtained for entropy andHelmholtz scaling approaches, at 2.73% and 2.72%, respectively. The modifiedentropy scaling approach presented an AAD value of 3.12%.  The results obtained with each ofthe binary and multicomponent mixtures allowed us to confirm the accuracy ofthe Helmholtz scaling, entropy scaling, and modified entropy scaling approachusing GERG 2008 in the prediction of natural gas viscosities when appropriatemixing rules were selected for each approach.