s.ahmad aboofazeli - Department of Chemical Engineering, School of Engineering, Persian Gulf University, Bushehr ۷۵۱۶۹-۱۳۷۹۸,
amir abbas izadpanah - Department of Chemical Engineering, School of Engineering, Persian Gulf University, Bushehr ۷۵۱۶۹-۱۳۷۹۸,
s.ali Mousavi-Dehghani - Upstream Software Development Plan, Research Institute of Petroleum Industry (RIPI/NIOC), P.O.Box:۱۴۷۵۷-۳۳۱۱, West End Entrance Blvd. Olympic Village Blvd. Tehran, Iran

The equation of state has been widely used to predict the thermodynamic properties and phase behavior of pure and multi-component systems in petroleum and chemical industries. However,they often fail in highly polar, hydrogen bonding and associating systems. Association equation ofstate (AEOS) can be used for the discrepancy due to the association concept. AEOS uses thephysical and chemical contributions to evaluate the phase behavior of associating fluids. In thiswork, a new Peng-Robinson based association equation of state has been developed. The new proposed AEOS is used to correlate the saturated properties of 19 associating pure compounds. In addition, the new AEOS satisfactorily extended to mixtures containing associating and nonassociatingcompounds and the VLE behavior of several important associating binary systemssuch as water/hydrocarbon, alcohol/hydrocarbon, alcohol/CO2 and the quaternary system of H2O/CH4/CO2/H2S has been represented. The results of this work are in good agreement with the other works and experimental results

association equation of state, hydrogen bonding, chemical theory, phase equilibrium