A 2.0 litre Diesel Engine with Low Pressure Exhaust Gas Recirculation and Advanced Cooling Systems

摘要

Engine testing is performed on a 2.0 litre diesel engine comparing high and low pressure EGR architectures. With low pressure EGR, six operating points chosen from the NEDC cycle achieved lower NO{sub}x emissions by 5 to 64% for similar fuel consumption and PM emissions compared to high pressure EGR. The lower intake manifold gas temperature and the improved homogeneity of the mixture of EGR and fresh air are among the advantages of low pressure EGR. However, one of the challenges of low pressure EGR is the formation of condensates in the EGR cooler and charge air cooler. This condensation is observed at coolant temperatures below 35°C, in quantities that can reach 1.5 l/h at 20°C. The condensate pH is observed as low as 2.6 and is found to contain strong acids, sulphur, organic acids, Al{sup}(3+) and traces of other metals.