Emission reduction in small displacement diesel engines using cooled exhaust gas recirculation

A reduced-order dynamic model is presented and experimentally validated to demonstrate the use of cooled exhaust gas recirculation to alleviate the tradeoff between nitric oxide reduction and performance preservation in a small displacement diesel engine. Exhaust gas recirculation (EGR) is an effective method for internal combustion engine oxides of nitrogen (NOx) reduction, but its thermal throttling diminishes power efficiency. The capacity to cool exhaust gases prior to merging with intake air may achieve the desired pollutant effect while minimizing engine performance losses.; Simulation and experimental results revealed significant NOx reductions throughout all testing scenarios using EGR, but also experienced a loss in engine torque. However, the use of cooled EGR realized a larger NOx reduction during most operating conditions while maintaining a smaller performance compromise. The concurrence between simulated and experimental trends establishes the simplified model as a predictive tool for diesel engine performance and emission studies.