Numerical investigation on diesel combustion and emissions with a standard combustion model and detailed chemistry

Rafał Pyszczek,Andrzej Teodorczyk,Carsten Schmalhorst

doi:10.19206/ce-116862

Abstract

The aim of this study was to determine possibilities of the soot and NOx emissions reduction from an existing heavy-duty compression-ignition (CI) engine based only on in-cylinder techniques. To that end numerical simulations of such processes as a multiphase fuel flow through injector nozzles, a liquid fuel jet breakup and evaporation, combustion and emissions formation were performed in AVL Fire 3D CFD software. The combustion process was calculated with the ECFM-3Z model and with the detailed n-heptane oxidation scheme that consisted of 76 species and 349 reactions. Both approaches of combustion modeling were validated against experimental data from the existing engine working under 75% and 100% loads. As for the reduction of the NOx emission an introduction of exhaust gas recirculation (EGR) was investigated. As for the soot concentration reduction such measures as an increased rail pressure, application of a post-injection and an increased injector nozzles conicity were investigated. Finally the ECFM-3Z model with emissions models, as well as the n-heptane mechanism predicted that it is possible to reach specified emissions limits with application of EGR, post-injection and increased nozzles conicity.

Highlights

The development of the industrial sector became the reason of the emissions growth
Model validation The numerical model needed to be validated against experimental data, in order to recognize that results obtained with simulations were trustworthy. Such results as IMEP, pressure trace, soot emission and NOx emission for 100% and 75% loads with 0% and 20% of exhaust gas recirculation (EGR) were validated against measurements for MIO cases with K0 nozzle and 1500 bar rail pressure
In this study 3D CFD numerical simulations of combustion were performed in order to investigate the possibilities of NOx and soot emissions reduction in heavy-duty CI engine

Summary

Introduction

The development of the industrial sector became the reason of the emissions growth. According to [1] transport is the source of 13% of the global greenhouse gas emissions. Apart from CO2, during combustion process in the internal combustion engines NOx, CO, unburned hydrocarbons (UHC) and particulate matter (mostly soot) are generated. These pollutants are harmful for the environment and for the humans. In the United States emission standards are managed on a national level by the Environmental Protection Agency (EPA) and currently Phase 3A is in force (2010-2016). As for the marine application engines emission standards are introduced by International Maritime Organization (IMO) which is the United Nations specialized agency with responsibility for the safety and security of shipping and the prevention of marine pollution by ships. The new standards Tier III that will be introduced in 2016 require reduction of NOx by 80% in regard to the current regulations in the Emission Control Areas [2]

Objectives

Results

Conclusion