Thermodynamic properties of methanol,water and ammonia predicted using CPA EOS+renormalization group theory

Alcohols,water and ammonia have many applications in industry.However,the hydrogen-bonding(association) interactions make descriptions of their thermodynamic properties by classical equations of state difficult,especially near the critical point where the true thermodynamic behavior is a consequence of long-range density fluctuations.The cubic plus association(CPA) equation of state with the Helmholtz energy modification given by renormalization group theory which accounts for the density fluctuations was used to predict the thermodynamic properties of methanol,water and ammonia near to and far from the critical point.The results show significant improvement in the representation of the critical properties and the phase equilibrium in the near critical point region.Good results were also obtained in the single-phase region.Thus,this method can describe the thermodynamic properties of various associating fluids.