using close-packed lattice models,a continuous thermodynamic framework is presented forphase-equilibrium calculations for binary solutions with a polydisperse polymer solute.An expressionfor the Helmholtz function of mixing is based on the revised Freed model developed previously.Asize parameter c_r and an energy parameter ε are used;the former can be temperature dependent,while the latter can depend on both temperature and chain-length of the polymer.The discretemulticomponent approach is adopted to derive expressions for chemical potentials,spinodals and criti-cal points.The continuous distribution function is then used in calculations of moments occurring inthose expressions.Computation programs are established for cloud-point-curve,shadow-curve,spinodal and critical-point calculations for polymer solutions with standard distribution or arbitrarydistribution of polymer.In the latter case,the derivative method developed previously is applied.lllustrations for phase-equilibrium calculations are shown using close-packed lattice models, a continuous thermodynamic framework is presented forphase-equilibrium calculations for binary solutions with a polydisperse polymer solute. An expression for the Helmholtz function of mixing is based on the revised Freed model developed previously. As parameter c_r and an energy parameter ε are used; the former can be temperature dependent, while the latter can depend on both temperature and chain-length of the polymer approach. The discreetultomponent approach is adopted to derive expressions for chemical potentials, spinodals and criti-cal points.The continuous distribution function is then used in calculations of moments occurring in those expressions. Computational programs are established for cloud-point-curve, shadow-curve, spinodal and critical-point calculations for polymer solutions with standard distribution or arbitrarydistribution of polymer. In the latter case, the derivative method developed previously is applied .lllustrations for phase-equilibrium calcu lations are shown