Effect of Exhaust Gas Recirculation Temperature on the Emission and Performance of a Single Cylinder Naturally Aspirated Stationary Diesel Engine

Stringent legislative emission norms demand to curb the stationary and automobile related engine pollution. Though several methods are available to control such harmful pollution, Exhaust Gas Recirculation, EGR is very popular in controlling pollution. EGR is one of the most effective means of reducing NOx emissions from diesel engines and is likely to be used in order to meet present and future strict emissions standards. The results of the experiments conducted on a single cylinder naturally aspirated stationary DI Diesel engine with two heat exchangers to vary the EGR temperatures are presented in this paper. Incorporation of two heat exchangers enabled to vary the temperature of the recirculated exhaust gas. Results are obtained for three different EGR cooling, first passing it through one heat exchanger then through two heat exchangers and finally recirculated without passing through any heat exchanger. As the test engine is meant for stationary application its speed is automatically governed. It was found that hot EGR renders significant reductions in NOx emission with minimum deterioration in UBHC, smoke and thermal efficiencies. The EGR percentage could not be extended beyond 50% as engine started running rough. A reduction in NOx up to 94% was recorded for hot EGR case. Without any remarkable drawbacks in fuel consumption, the NOx and HC emissions can be considerably reduced at low part load operation. The EGR has a beneficial effect especially at the low and medium part load range.