Abstract
Exhaust gases recirculation is becoming a popular strategy to address two issues that arise in heavily downsized turbocharged gasoline engines at full load operation: knocking at low engine speeds and fuel enrichment for turbine protection at high engine speeds. EGR cooler behaviour is a key aspect to ensure a proper operation of the EGR strategy. Fouling phenomenon affects the pressure loss in the EGR cooler and reduces the heat transfer from the exhaust gases to the coolant fluid. Additionally, when the engine starts and coolant temperature is reduced, water condensation appears in the exhaust gases. In this work both phenomena, fouling and condensation, have been explored in two different EGR loop configurations: LP (downstream the catalyst to upstream the compressor) and mixed (upstream the turbine to upstream the compressor). Fouling assessment was performed by tracking the pressure loss and thermal efficiency in an engine test cell with the engine running conditions similar to real-life driving conditions. Condensates were extracted at the EGR cooler outlet in five steady operation points and a chemical analysis was done. The effect of the sulfur content in the gasoline was analyzed in the condensates composition with three different levels: conventional EU, 2000 and 4000 ppm.
