Re-evaluating the CPA EoS for improving critical points and derivative properties description

- A modified CPA approach, taking into account the description of the critical point is proposed and applied for alcohols.
- A constant associative energy was applied, while for associative volume a constant value was applied for most alcohols.
- While describing Tc and Pc, CPA presents accurate results for liq. density, Hvap, liq. Cp and Psat.
- Binary VLE and LLE results present similar accuracy to those obtained before with CPA.

Although the CPA EoS was initially developed 20 years ago to meet industrial solicitations, namely the need to describe mixtures of hydrocarbons and water, including the formation and dissociation of hydrates, it has only recently received a widespread use in mid-stream and downstream oil and gas processing, or in the petrochemical and chemical industries. One of the reasons for such limited use of the model in the industry is the necessity to parameterize every associating component from saturation data. This involves access to pure component databases and some advanced knowledge in thermodynamics and numerical methods, which are often behind the scope of process design engineers.This work revisits the CPA model, evaluating its strengths and weaknesses and attempting at identifying some opportunities for improvement. Using n-alkanols from C1 to C10 and their mixtures with other n-alkanols and n-alkanes, it investigates the description of the pure component critical points, saturated liquid densities as a function of temperature and some second-order derivative properties. It also explores new methodologies to regress the CPA parameters in a more systematic way, making it easier to generate parameters with less intervention from the user.

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