CI ENGINE MODELING AND EXPERIMENTAL STUDIES FOR LOWER EXHAUST EMISSIONS

Year 2016, Issue: 4, 4 - 13, 01.12.2016

Mehmet Zafer Gul Mustafa Yılmaz Hasan Köten İsmail Hakki Savcı

Abstract

In recent years, automotive companies and research centers have utilized different techniques to ensure tightened
emission rules. These studies generally are divided into two main categories: in-cylinder and after-treatment
applications. In the first stage, harmful exhaust emissions were decreased by optimizing engine parameters.
After-treatment applications come into play after exhaust port for irreducible emissions. In the studies, done at
Marmara University, three important works examined to get ultra-low emission for a single cylinder diesel
engine. In the first study, engine parameters such as compression ratio (CR), intake and exhaust valve timings,
mass flow rate were optimized for a range of engine speed. Then for the same engine injection parameters such
as start of injection (SOI), injector cone angle, and split injection structures were examined to get optimum
parameters for the diesel engine. In CR studies different combustion chambers were tested according to injector
cone angles and fuel-wall interaction. In the second study, in addition to the above studies, dual fuel compressed
biogas (CBG) and diesel combustion were analyzed under different engine loads both experimentally and
computationally. Optimized single fuel diesel cases were compared with CBG + Diesel dual fuel cases which
employed port injection for CBG fuel. In dual fuel engine applications, CBG fuel and air mixture is induced
from intake port and this air-fuel mixture is ignited by pilot diesel fuel near top dead center (TDC). In dual fuel
engine mode, exhaust emissions reduced considerably especially in NOx and particulate matter (PM) because of
methane (CH4) rate and optimized engine parameters. The third study is focused on aftertreatment systems to
minimize residual exhaust emissions. In this study, computational fluid dynamic (CFD) methodology was
developed with conjugate heat transfer, spray, deposit and chemical reaction modeling then emission prediction
tool was developed based on the CFD results with deposit prediction mechanism. CFD and deposit results were
correlated with image processing tool in flow test bench.

Keywords

CFD, CI engine, emission, optimization, aftertreatment, SCR, NOX