Reduction of the Pollutant Emissions from a Diesel Engine by the Application of Dimethyl Ether (DME) and the Control of the Intake Oxygen Flow Rate

Abstract

The aim of this study was to investigate the effects of varying the global equivalence ratio and intake oxygen flow-rate on the combustion and exhaust emission characteristics of dimethyl ether (DME)-fueled combustion engine. This study dealt with the reduction characteristics of HC and CO emissions, as well as a simultaneous decrease of NOx and soot in a DME-fueled single-cylinder combustion engine. Our findings demonstrate that increasing the global equivalence ratio while holding the intake oxygen flow-rate constant caused the premixed combustion duration (CA10-CA50) to increase. Additionally, it was observed that decreasing the intake oxygen flow-rate while holding the injection quantity constant shortens the duration of CA10-CA50. In this investigation, simultaneous reduction of soot and indicated specific (IS)-NOx emissions from a diesel engine can be achieved by fueling with DME and setting a high EGR rate (low intake oxygen flow-rate). Further, applying high equivalence ratio together with a high EGR rate resulted in a near zero level of soot and IS-NOx emissions in DME combustion. In addition, DME combustion yielded lower IS-CO and IS-HC emissions than diesel combustion, even with a low intake oxygen flow-rate.