Exhaust Gas Fuel Reforming for Diesel Engines - A Way to Reduce Smoke and NOX Emissions Simultaneously

This paper describes the results of an experimental investigation of the exhaust gas assisted fuel reforming process as a means of achieving reduction of both smoke and NO_x diesel engine emissions. Using a reforming mini-reactor with exhaust gas from a single-cylinder DI diesel engine, diesel fuel was reformed and a hydrogen-rich gas was produced. The effects of the reforming process on the engine operation were studied by adding simulated reformer product gas to the engine inlet. In this way, the engine was operated as if a reformer would have been incorporated in the exhaust gas recirculation system (EGR) system providing the engine with ‘reformed EGR’ (REGR). Lower levels of REGR resulted in simultaneous reduction of smoke and NO_x while increased REGR reduced smoke further but tended to increase NO_x. With appropriate adjustment of the injection timing the adverse effects on NO_x were overcome while smoke was still kept at low levels and the engine fuel consumption and efficiency were improved. The effects of REGR on cylinder pressure, heat release, emissions and fuel economy are presented and discussed.