Exhaust Gas Recirculation System

It is today undoubted that humans have to reduce their impacton the environment. Internal combustion engines, being the major power source in the transportation sector as well as inindividual transport, play an important role in the man-made emissions. While the mobility in the world is growing, it is important to reduce the emissions that result from transportation. The diesel engine provides a high efficiency and hence it canhelp to reduce CO2 emissions, which are believed to be themain cause of global warming. Diesel exhaust also contains toxic gases, mainly nitrogen oxides (NOX) and soot particles. These emissions are therefore limited by the authorities in most countries. A way to reduce the nitrogen oxide emissions of a diesel engine is the use of exhaust gas recirculation, EGR. Here, a part of the exhaust gases is rerouted into the combustion chamber.  This leads to a lower peak combustion temperature which in turn reduces the formation of NOX. In modern turbocharged engines it can be problematic to provide the amount of EGR that is needed to reach the emission limits. Other concerns can be the transient response of both the EGR-system and the engine. This work provides a simulative comparison of different EGRsystems,such as long-route EGR, short-route EGR, hybrid EGR, a system with a reed valve and a system with an EGR pump. Both the steady-state performance and transient performance are compared. In steady-state the focus is the fuel efficiency. In transient conditions both the reaction on changed EGR-demands and the torque response are analyzed.