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Computer Simulation of Gasoline-Direct-Injected (Gdi) Extended Expansion Engine
Technical Paper
2005-26-057
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Event:
SIAT 2005
Language:
English
Abstract
This paper deals mainly with computer simulation of processes of
Gasoline Direct Injection (GDI) associated with Extended Expansion
Engine (EEE) concept applied to a four-stroke, single-cylinder SI
engine.
In the case of standard SI engines, part-load brake thermal
efficiencies are low due to higher pumping losses. The pumping
losses can be reduced by operating the engine always at full
throttle as done in extended expansion engine. In extended
expansion engine, higher Geometric Expansion Ratio (GER) compared
to Effective Compression Ratio (ECR) is responsible for better
performance at part loads. Usually, in this engine, by delaying
inlet valve closure timing along with reduced clearance volume,
extended expansion is achieved. Experimentally many researchers
have proved that variable valve timing and variable compression
ratio techniques adopted in SI engines, improves the part- load
performance greatly.
Nowadays, load control in the SI engines is also done by
Gasoline Direct Injection (GDI) of the fuel into the cylinder. In
these engines, by electronic means, it is possible to meter the
fuel accurately thereby improving the fuel economy to a great
extent. Also, stratification is possible with GDI thereby overall
lean mixtures can be used with high compression ratios, which
further increase the thermal efficiency. The other advantage of the
GDI concept is that it helps to reduce emissions, which is very
much required for today's emission norms.
In this work, an attempt has been made to develop a computer
program, which involves thermodynamic and phenomenological models
for simulating the processes of the GDI associated with Extended
Expansion Engine (hereafter called as GIEEE). Appropriate
sub-models have been chosen and used for predicting heat transfer,
friction and droplet evaporation, etc. Combustion model involves
premixed and diffusion phases, which predicts mass burning rate,
ignition delay and combustion duration, etc. Also, sub-models for
calculating flame front area, flame speed, and chemical equilibrium
composition of burned product species have been used. Exhaust
emission models are also involved in the program to predict the
unburned hydrocarbons, carbon monoxide and nitric oxide
emissions.
Firstly, some of the results obtained by predictions using the
computer code developed in this work have been validated with the
available experimental results in the literature. It seems that the
predicted results match reasonably well with the experimental
values. Secondly, the computer code has been used for further
parametric studies. Finally, it is concluded that the computer code
developed in this work can be used with confidence for optimizing
the parameters of GIEEE for the given configuration of the
engine.