(279c) Thirty Years With Association Models – What Have We Learnt ?

Kontogeorgis, G., Center for Energy Resources Engineering (CERE), Technical University of Denmark

Demanding applications in the oil & gas and chemical industries require advanced models – better than the cubic equations of state. Some of the most successful such models are the so-called association theories, which account explicitly for hydrogen bonding and other complex interactions.

Many such models have been developed over the last 30 years based on chemical, lattice and perturbation theories. Most are expressed in the form of equations of state. They have been used extensively for describing a wide range of complex systems, including associating fluids, polymers, electrolytes and biomolecules. Thus, they have been applied to petroleum, chemical and pharmaceutical industries. Recent books [1-4] have summarized many of these models.

In this presentation, we will present capabilities and limitations of some of these association theories based on our research with the CPA, PC-SAFT and NRHB equations of state. We will present similarities and differences in their performances and emphasize applications in some of the following fields:

  • Petroleum industry especially oil – water – gas hydrate inhibitor chemicals
  • CO2 capture and storage
  • Chemical industry especially mixtures with organic acids and biofuels
  • Electrolytes
  • Derivative properties
  • Polymers and pharmaceuticals

We will clarify where today association theories perform better than the state of the art models of the previous generation and we will also illustrate what is still challenging almost 30 years after the first systematic applications of association models.


[1] G.M. Kontogeorgis, G.K. Folas. Thermodynamic models for industrial applications. From Classical and Advanced mixing rules to association theories, Wiley, 2010.

[2] A.R.H. Goodwin, J. V. Sengers, C.J. Peters Eds, Applied Thermodynamics of Fluids. RSC Publishing, 2010.

[3] J-Ch. de Hemptinne, J-M. Ledanois, P. Mougin, A. Barreau, Select Thermodynamic models for process simulation. A practical guide using a three steps methodology. Editions Technip, 2012.

[4] J.M.  Prausnitz, R.N. Lichtenthaler, E.G. de Azevedo. Molecular Thermodynamics of Fluid-Phase Equilibria (3rd edition). Prentice Hall Int., 1999.