Computational Investigation of Low Load Operation in a Light-Duty Gasoline Direct Injection Compression Ignition [GDICI] Engine Using Single-Injection Strategy 2014-01-1297

The use of gasoline in a compression ignition engine has been a research focus lately due to the ability of gasoline to provide more premixing, resulting in controlled emissions of the nitrogen oxides [NOx] and particulate matter. The present study assesses the reactivity of 93 RON [87AKI] gasoline in a GM 1.9L 4-cylinder diesel engine, to extend the low load limit. A single injection strategy was used in available experiments where the injection timing was varied from −42 to −9 deg ATDC, with a step-size of 3 deg. The minimum fueling level was defined in the experiments such that the coefficient of variance [COV] of indicated mean effective pressure [IMEP] was less than 3%. The study revealed that injection at −27 deg ATDC allowed a minimum load of 2 bar BMEP. Also, advancement in the start of injection [SOI] timing in the experiments caused an earlier CA50, which became retarded with further advancement in SOI timing. To help explain these behaviors, simulations were carried out using the KIVA3V CFD code coupled with a Jacobian chemistry solver, SpeedChem. Six experimental data points were considered in order to explain the CA50 trend. The results showed that at low load conditions, the IVC temperature has a significant effect on combustion phasing control. Additional computational investigations were carried out by varying the injected fuel amount, SOI timing, swirl and nozzle hole diameter to study their effects on load minimization.