Application of a mini-dilution tube in the study of fuel effects on stratified charge engine emissions and combustion

A mini-dilution tube to measure particulate emissions is described and results obtained in an application are presented. The application selected is a study of fuel effects on stratified charge engine emission and combustion characteristics. The mini-dilution tube was developed to provide a capability for particulate measurements with dynamometer engines. The device has been demonstrated to yield particulate mass results agreeing to within 10 percent of those with a full scale tunnel in steady state tests with diesel powered vehicles. A PROCO engine modified by incorporation of Torch Ignition was used in the study. Fuels were a wide cut gasoline, methanol and Indolene Clear gasoline. The engine was operated at a speed of 1250 rpm with an indicated mean effective pressure of 390 kPa. Spark timing, injection timing, EGR and equivalence ratio were varied. Gaseous and particulate emissions and combustion characteristics of the wide cut gasoline and Indolene Clear were found to be nearly identical. with methanol the HC, NOx and particulate emissions were lower than with the gasolines but CO was higher. Combustion rates with methanol were higher than with the gasolines.