Abstract:
Research in the utilization of hydrogen and syngas
has significantly increased due to their cleanburning
properties and the prospect of production
from several renewable resources. Homogeneous charge
compression ignition (HCCI) engine is low-temperature
combustion (LTC) concept which combines the best
features of conventional spark-ignition (SI) and compression-
ignition (CI) engines. HCCI combustion engine has
shown the potential for higher efficiency and ultralow NOx
and soot emissions. In this study, syngas fueled HCCI
combustion is simulated using stochastic reactor model
(SRM) with a detailed chemical kinetic mechanism (32
species and 173 reactions). Detailed syngas oxidation mechanism
included NOx reactions also. In SRM models physical
parameters are described by a probability density
function (PDF). These parameters does not vary within the
combustion chamber, and thus the spatial distribution (due
to local inhomogeneity’s) of the charge is represented in
terms of a PDF. The SRM based approach simplifies many
aspects of CFD processes while retaining the predictive
capability similar to 3-D CFD codes. Simulations are
conducted for different engine operating conditions by
varying intake temperature, engine load, and speed at
compression ratio 19:1 for an engine of 0.435 L swept
volume. The simulation shows good conformity with experimental
engine data. Start of combustion and cylinder pressures
are predicted with sufficient accuracy. Sensitivity
analysis is conducted to determine the influential reactions
in syngas oxidation. Combustion characteristics and efficiency
of an engine operating on varying blends of synthesis
gas in HCCI mode are also investigated.
