apour pressure data of substances were analyzed and studied in the paper. Antoineequation was considered to be most suitable change law of saturated vapour presstire andsaturated temperature. But the constants in Antoine equation were determined by regressionof measured vapour pressure data. The calculated method was presented about constantsof Antoine equation in the paper.The method was examined by a lot of substances, givingsatisfactory results.
Based on the analysis for the cubic equations of state, this paper proposes the improving equation of state-Exp-RK equation. Polar substances, associated substances and supercritrical working substances have been calculated by this equation, giving satisfactory results.
