Thermodynamics Analysis of Biodiesel Fuels

Abstract

The world energy demand continues to increase. The most feasible way to meet this growing demand is by utilizing alternative fuels. One such fuel that exhibits great potential is bio fuel, in particular, biodiesel. The major energy demand is fulfilled from the conventional energy resources like coal, petroleum and natural gas. Petroleum-based fuels are limited reserves concentrated in certain regions of the world. These sources are in the verge of getting extinct. The scarcity of known petroleum reserves will make renewable energy resources more attractive. The advantages of biodiesel as diesel fuel are liquid nature portability, ready availability, renewability, higher combustion efficiency, lower sulfur and aromatic content, higher cetane number and higher biodegradability. Thermodynamic study of the biodiesel fuels is very important. Firstly it provides an idea about optimum temperature and pressure condition for reaction. It can also throw the light on ratio of reactants to be used. The vapour liquid equilibrium data can be helpful to design separation of mixture. The study is based on the fundamentals of thermodynamic such as determination of Gibbs energy and Enthalpy, which are important to determine the favourable condition for production of biodiesel. By application of the thermodynamics fundamental we have seen the effect of temperature on reaction equilibrium constant and reaction coordinate. The work also includes finding out physical properties like critical properties, vapor pressure of different fatty acids. Estimation of phase equilibrium using equation of state requires a proper choice of cohesion factor. In the current work, we have selected some ten cohesion factor relations and compared them for the accuracy in predicating vapor pressure. We have also developed the cohesion function for fatty acids. By the help of this one can estimate the Vapor Liquid Equilibrium as well as Cloud Point of biodiesel.