2009 Volume 40 Issue 5 Pages 1229-1234
EGR combustion system is one of the pormising ways of NOx reduction in diesel engine. In EGR system, hot exhaust gas is recirculated from the exhaust side of engine to the intake side. To ensure the high ratio of EGR and high volumetric efficiency of it, hot exhaust gas should be cooled down with EGR cooler. Then EGR cooler with high cooling performance is required for high efficiency and ultra low emission diesel engine. To improve the performance of EGR cooler, exhaust gas deposits in it should be eliminated, because heat transfer performance is deteriorated with the deposits. In this study, new evaluation method of deposits in EGR cooler was proposed as teh first step of EGR cooler improvement. Deposits in EGR cooler were oxidized in a special designed furnace and soot and hydrocarbon in the deposits were estimated with gas analysis of O2 and CO2 in the furnace. Total deposits mass obtained from gas analysis showed good agreement with the deposits mass obtained by a gravimetric method. The gas analysis showed that 80% of deposits mass was carbon. Further, heat transfer performance of the EGR cooler was evaluated and its relationship with deposits was discussed.
