A Comparison Between Different EGR Systems for HD Diesel Engines and Their Effect on Performance, Fuel Consumption and Emissions

An effective way of meeting future emission legislation with a heavy-duty diesel engine is to equip the engine with an EGR-system combined with a particulate trap. In this study the work was concentrated on the EGR-system. The goal of the investigation was to find an EGR-system that could deliver enough air and exhaust gases to the engine to meet the Euro IV emission levels with minimum penalty on engine performance and fuel consumption, starting from a Euro 0 engine. The tests showed that it was possible to significantly improve emissions with all the tested EGR-systems in combination with a particulate trap, but notable differences with respect to fuel consumption were found.

For all EGR systems under study, the main factors influencing engine performance and fuel consumption were found to be.

• Pumping losses.
• Residual gases.
• Temperature of the recirculated exhaust gases.
• Distribution of the recirculated exhaust gases between the cylinders