Analysis of combustion and emission characteristics of a diesel engine fueled with alternative fuel by thermodynamic modeling

Abstract

With depletion of conventional fuel source at tremendous rate and increasing environment pollution has motivated extensive research in alternative fuel and engine design. Biodiesel being environmental friendly, usually lower exhaust emission and better lubrication properties can be suitable alternative. However the use of biodiesel fuel in diesel engines has associated with some of the drawbacks like higher nitric oxide (NO) emissions, poor cold flow properties and oxidation stability. Several measures have been taken to overcome these demerits for better utilization of biodiesel in diesel engines. In this work an attempt has been made to reduce the NO emissions of biodiesel by emulsifying Wood Pyrolysis Oil (WPO) in lower percentages with Jatropha Methyl Ester (JME). The experiment was performed on a single cylinder, air cooled, direct injection diesel engine for this purpose. The experimental results are validated with a two zone model program developed using a MATLAB software. One zone consists of pure air called non burning zone and the other zone consists of fuel and combustion products called burning zone. The first law of thermodynamics and equations of state are applied in each of the two zones to get the temperature and pressure inside the combustion chamber. Using the two zone combustion model the combustion parameters and the chemical equilibrium composition of all the species were determined theoretically. The extended Zeldovich mechanism is used for predicting the NO emissions and soot density is calculated using a semi-empirical model. The comparisons of experimental and theoretical results are presented in this paper.