Multi-zone phenomenological model of combustion and emission characteristics and parametric investigations for split injections and multiple injections in common-rail direct-injection diesel engines

Abstract

This paper presents the formulation of a multi-zone zone phenomenological model for predicting the combustion and emission characteristics of split-injection and multiple-injection common-rail direct-injection diesel engines. In this model, the instantaneous combustion space is divided into two regions, namely the spray zones and the surrounding air. The model predictions for combustion and emissions for split injections and multiple injections are validated with the measured results on a wide range of injection schedules available in the literature. The comparisons reveal the good predictive ability of the model with reasonable accuracy and demonstrate the applicability of the multi-zone model to multiple-injection common-rail direct-injection engines. Hence, the model is used for parametric investigations to analyse the effect of split injections and multiple injections on the combustion and emission characteristics of common-rail direct-injection diesel engines. The parametric investigations show that an increase in the pilot fuel quantity increases the nitrogen oxide emissions and reduces the soot emissions while the dwell period has to be optimized for simultaneous reductions in the nitrogen oxide emissions and the soot emissions. Therefore the present model can be used to achieve an optimal injection schedule for given engine operating conditions.

Emission and performance characteristics of CRDI diesel engine using Quadruple injection strategy with different pilots and post injection timing

“…The post/after injection enhances the late-cycle mixing of engine combustion at low-temperature combustion (LTC) regime which helps to reduce the soot/smoke formation [7,8,14,17,22,23,26]. Furthermore, among the different quadruple (epMa) injection combinations closed to main injection or retarded pilots (both e and p) are effective in smoke reduction.…”

“…There are numerous researches take place in the domain of combustion optimization of modern diesel engine with different multiple injection strategies [2][3][4][5][6][7][8][9][10][11], injection parameter optimization (injection timing, Injection pressure, injection dwell, fuel quantity, rate shaped etc.) [12][13][14][15][16][17][18][19], alternative fuels [20,21] and EGR or high EGR-low temperature combustion (LTC) [22][23][24][25]; and predictive combustion model [26] with similar objectives. The injection parameter optimization is the sub set of multiple fuel injections.…”

“…Rajkumar et al [26] have developed a multi-zone phenomenological model for modern diesel engine to predict the emissions and combustion characteristics of Split and Multiple injections (double and Triple). They conveyed the simultaneous decrease in smoke and NOx with rise of pilot fuel quantity and an optimize dwell between the main and pilot injection.…”

A review of phenomenological spray penetration modeling for diesel engines with advanced injection strategy

“…Rajkumar and Sudarshan 100 presented a formulation of the spray under split-injection direct-injection diesel engines. The chamber domain was divided into the spray zones and the surrounding air, and the split injections were accounted by, respectively, calculating air entrainment during fuel injection of each pulse and after the respective pulse of the injection period by the momentum conservation and turbulent mixing.…”

Influence of Engine Speed on Mixing and Emission Characteristics of Multiple-Injection Common Rail Direct Injection Diesel Engine

“…It is quite difficult to conduct direct experimental investigations for measuring the mixing characteristics of an engine and relate its effect on exhaust emission. Hence, this work is aimed to study the significance of mixing rate and relate it to emission changes using a validated phenomenological model [2] at a wide range of engine speed and load conditions. In phenomenological model, empirical correlations are used to describe the various processes involved in diesel engine operation.…”