The interest in fuel savings and pollution control by internal combustion engines has been a central issue for more than three decades. A great deal of attention has been focused on engine design and almost every aspect of fuel combustion processes. In this research, fuel injection and atomization is one field of major interest. To promote a more efficient and cleaner burning, the fuel has to be conveyed to the combustion chamber in smaller droplets to be evaporated and mixed with air. This could be achieved by different methods such as higher injection pressures, and multi-fuel injections. A new concept to improve engine performance and reduce emissions in diesel engine by trying to reduce the need for such a high pressure, is to achieve smaller droplet size by bubbling CO2 through fuel before injection due to the fact that droplet size of fuel containing CO2 is much more uniform and smaller than that of pure diesel spray. In this research, three experimental stages to study theeffect of diesel enrichment with CO2 are performed. In addition a theoretical study on diesel enrichment with exhaust gases is attempted.