JFET_V3_N3_RP4 C. Kannan P. Tamil Porai Journal on Future Engineering and Technology 2230 – 7184 3 3 29 40 Combustion, Porous media, Biodiesel blend At present, the emissions of internal combustion engine can only be improved by catalytic treatments of the exhaust gases. However, such treatments result in high cost and relatively low conversion efficiency [1]. Out of the pollutants from diesel engines, the Nitric Oxide (NOx) emission seriously threatens the environment. The vehicle manufacturers are trying various combinations of technologies such as EGR (homogeneous & stratified), water-diesel fuel emulsion injection, charge stratification, high pressure injection, pilot injection, variable compression ratio etc. to reduce or control the NOx emission [1]. The usage of biodiesel blends in Direct Injection (DI) diesel engine shows its potential to reduce the exhaust emissions. But still, the NOx emissions from those engines are found to be higher with a subsequent reduction in thermal efficiency [2]. This necessitates a further improvement either in the combustion process or post-combustion processes of those engines fuelled with biodiesel blends. This paper suggests a new combustion technique called Porous Medium (PM) combustion, which could be used to reduce the NOx emissions with a remarkable improvement in the thermal efficiency of a diesel engine operated on biodiesel blends. February - April 2008 Copyright © 2008 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=646