A new development of equation of state for square-well chain-like molecules with variable width 1.1≤λ≤3

Equation of state for square-well chain molecules with variable range. I: Application for pure substances

“…The predicted compressibility factor and vapor-liquid coexistence curves for pure model fluids and their mixtures were in good agreement with the computer simulation data. It was also found that SWCF-VR EOS can give good correlations of pVT and VLE for several illustrative pure real substances and their mixtures [18]. For the refrigerants system, the calculated VLE are also in good agreement with the experimental data [21].…”

“…According to our previous work [18], for a square-well chain fluid with molecules composed of r square-well sphere segments with a diameter of , the compressibility factor of a system can be expressed as…”

“…K HS represents the isothermal compressibility of hard-sphere monomers and the expression is the same as one in our previous work [18]. Á = s 3 /6 is the reduced segment density, s = r is the number density of segments, is the number density of chain molecules.…”

“…In our previous work [18], an EOS for square-well chain molecules with variable rang (SWCF-VR) was developed based on statistical mechanics for chemical association. In this EOS, two modifications have been made.…”

Accurate statistical associating fluid theory for chain molecules formed from Mie segments

“…The earlier versions of the SAFT EOS were based on a reference system of hard spheres. In morerecent versions of the theory, reference fluids represented with the square-well, [56][57][58][59][60] 71 and SAFT-VR (the latter implemented for both the SW 56 and LJ 65 potentials) has been reported, [72][73][74] and it was demonstrated that EOSs based on a hard-core or LJ pair potential do not generally provide one with an adequate representation of thermodynamic second-derivative properties such as the isothermal compressibility or the speed of sound in the compressed liquid phase; the description of these properties is found to be no better than that obtained with EOSs of the conventional van der Waals form such as the Peng-Robinson 75 (PR) or Soave-Redlich-Kwong 76 (SRK) cubic relations. In order to overcome these limitations a generic description of the interactions can be introduced, 72 using the Mie potential to describe the monomer-monomer interactions between the segments making up the molecules.…”