Prediction of Vapor Pressure of Fatty Acid Methyl Esters using Cubic Equation of State

Abstract

Fossil fuels are depleting at a rapid rate, due to their ever increasing demand and so there is a need for alternative and sustainable fuel. Biodiesel can be a promising alternative for petroleum based diesel fuels. Biodiesel is a mixture of fatty acid alkyl esters produced by the transesterification of vegetable oils/animal fats with alcohol in the presence of catalyst. Vapour pressure of biodiesel (FAME’s) is a very important property because combustion characteristics, volatility, safety and stability of fuel depend on it. In the present work ,prediction of vapour pressure of nine fatty acid methyl esters (FAME’s) was done using Peng-Robinson Cubic Equation of State (PR-CEOS) at zero pressure fugacity condition. The estimation of critical properties like critical temperature (Tc) and critical pressure (Pc) was also done as they are used as input for the prediction of vapour pressure using PR-CEOS at zero pressure fugacity condition. Eight cohesion factor models were used in PR CEOS for the prediction of vapour pressure. The estimated values of vapor pressure were compared with the experimental values (244 data points) of vapor pressure obtained from literature. In this work, Heyen1 and SRK type cohesion factor models are being proposed for the prediction of vapour pressure of FAME’s by PR-CEOS.