DETERMINATION OF KINETIC PARAMETERS FOR THE COMBUSTION OF JATROPHA BASED BIO-DIESEL

Abstract

Laminar burning propagation of bio-diesel air mixture has been studied in a spherical bomb, using the pressure — time records. Initial pressure and temperature are varied to cover a range of I bar-4 bar and 443K-523K respectively. The range of measurements covered the equivalence ratio from 0.8 to 1.2. Pressure-time records have been used to calculate the flame velocity, burned gas fraction, flame position etc., using a simplified, two zone thermodynamic model, assuming equilibrium composition and homogenous mixture for the burned gases. It is also assumed frozen composition and isentropic compression for the unburned mixture. For each experimental run, instantaneous burning velocities were calculated in the range of 1.5P0 to 0.75 Pmax and the laminar burning velocity values between the burned mass fraction of 0.2 and 0.3 were averaged to get burning velocity value for a particular experimental run. Overall reaction order and activation energy are calculated from burning velocity at each given condition of temperature. It is found that for the bio diesel-air mixture the laminar burning velocity decreases with pressure and increases with temperature. With respect to equivalence ratio, the burning velocity is relatively small with lean mixture but this increases continuously as the mixture is made progressively richer up to stoichiometric ratio and at =1.076 for initial pressure 2 bar and initial temperature 483K, it has peak. After that it begins to drop down with increasing mixture richness. A comparison of the trends of burning velocity variation with pressure with the results of other researchers, who have worked on different fuel-air mixtures, shows reasonably good agreement. This agreement gives confidence in the result of the present study to conclude the effects of various parameters on laminar burning velocity of biodiesel — air mixture.