MECHANISMS OF IGNITION ENHANCEMENT IN METHANOL-DIMETHYL ETHER DIESELS

ALTHOUGH METHANOL FUELED DIESELS ARE AN ATTRACTIVE MEANS OF MEETING THE 1991 DIESEL PARTICULATE STANDARDS, THEY ARE NOT YET PRACTICAL BECAUSE THE IGNITION DELAY IS TOO LONG UNDER TYPICAL OPERATING CONDITIONS. ON BOARD PRODUCTION OF THE IGNITION ENHANCER DIMETHYL ETHER (DME) FROM METHANOL, FOLLOWED BY ASPIRATION OF THE DME INTO THE CYLINDER HAS BEEN SHOWN TO REDUCE SIGNIFICANTLY THE IGNITION DELAY. HOWEVER, NO INFORMATION IS AVAILABLE ON THE MECHANISM BY WHICH DME ENHANCES IGNITION OF THE METHANOL, AND LITTLE QUANTITATIVE DATA IS AVAILABLE ON THE EFFECT OF DME CONCENTRATION ON IGNITION DELAY. DEVELOPMENT OF DME ENHANCED, METHANOL FUELED COMPRESSION IGNITION ENGINES IS BEST CARRIED OUT WITH A FUNDAMENTAL UNDERSTANDING OF THE COMBUSTION PROCESS. TDA RESEARCH PROPOSES TO DEVELOP A MECHANISTIC MODEL OF DME COMBUSTION, VALIDATE IT AGAINST EXISTING IGNITION DELAY DATA, AND MERGE THE DME COMBUSTION MODEL WITH EXISTING MODELS OF METHANOL COMBUSTION. THE INSIGHTS AND PREDICTIONS DERIVED FROM THE MODEL WILL BE USED TO GUIDE EXPERIMENTS AIMED FIRSTAT DETERMINING THE EFFECT OF DME CONCENTRATION ON IGNITION DELAY, AND ULTIMATELY AT DETERMINING THE OPTIMAL STRATEGIES FOR DME ENHANCEMENT OF METHANOL COMBUSTION.