Thermodynamic study on cloud point of biodiesel with its fatty acid composition

A thermodynamic study was made for binary mixture of various fatty acid methyl esters to establish a prediction model for the cloud point of actual biodiesel fuel from various feedstocks. When considering a eutectic system for ester mixture, measured values of cloud point were fitted well with a theoretical curve according to solid–liquid equilibria, even though an ideal solution was assumed. A simple model to agree with experimental results was, thus, proposed for predicting the cloud point of actual biodiesel. Through this study, it was found that cloud point of biodiesel could be determined only by the amount of saturated fatty acid methyl esters regardless of composition of unsaturated esters.