Studying the Influence of Direct Injection on PCCI Combustion and Emissions at Engine Idle Condition Using Two Dimensional CFD and Stochastic Reactor Model

Abstract

A detailed chemical model was implemented in the KIVA-3V two dimensional CFD code to investigate the effects of the spray cone angle and injection timing on the PCCI combustion process and emissions in an optical research diesel engine. A detailed chemical model for Primary Reference Fuel (PRF) consisting of 157 species and 1552 reactions was used to simulate diesel fuel chemistry. The model validation shows good agreement between the predicted and measured pressure and emissions data in the selected cases with various spray angles and injection timings. If the injection is retarded to -50 • ATDC, the spray impingement at the edge of the piston corner with 100 • injection angle was shown to enhance the mixing of air and fuel. The minimum fuel loss and more widely distributed fuel vapour contribute to improving combustion efficiency and lowering uHC and CO emissions in the engine idle condition. Finally, the coupling of CFD and multi-zone Stochastic Reactor Model (SRM) was demonstrated to show improvement in CO and uHC emissions prediction.

Towards a detailed soot model for internal combustion engines

“…The Stochastic Reactor Model (SRM) engine code has been successfully employed in a number of earlier studies (not involving soot formation) such as port fuel injected HCCI combustion [19], single early direct injection HCCI [21], dual injection HCCI [22], multi-cycle transient simulation and control [23], and has been coupled to the Computational Fluid Dynamics (CFD) code KIVA [24].…”

“…As engine model we use the Stochastic Reactor Model (SRM) [18][19][20][21][22][23][24] which includes detailed chemical kinetics, and possesses sub-models for turbulent mixing and convective heat loss, thereby accounting for inhomogeneities, i.e. stratification in composition as well as temperature.…”

Predicting auto-ignition characteristics of RCCI combustion using a multi-zone model

“…As PCCI-like combustion is mainly governed by auto-ignition and not by flame propagation [4][5][6][7] multi-zone approaches are believed to be a feasible approximation for this combustion regime. The main advantage of multi-zone models over computational fluid dynamics (CFD) tools is that more detailed chemical mechanisms can be applied directly.…”

Simulating Combustion of Practical Fuels and Blends for Modern Engine Applications Using Detailed Chemical Kinetics

“…However in this work, the code has not been developed and is only used as a tool hence the model is only described briefly here. The SRM is now a well established tool for computing engine combustion events and emissions with an history of successful validation in a number of engine related applications and results published in a large number of research articles [11][12][13][14][15][16][17][18][19][20][21]. It has been successfully employed in a number of earlier studies such as port fuel injected HCCI combustion [11,12], alternative fuel blends [13,14], single early direct injection HCCI [15], dual injection HCCI [16], multi-cycle transient simulation and control [17 -19], soot formation [20], and has been coupled to the Computational Fluid Dynamics (CFD) code KIVA [21].…”