A Sequential Chemical Kinetics-CFD-Chemical Kinetics Methodology to Predict HCCI Combustion and Main Emissions 2012-01-1119
This study presents the development of a new HCCI simulation
methodology. The proposed method is based on the sequential
coupling of CFD analysis prior to autoignition, followed by
multi-zone chemical kinetics analysis of the combustion process
during the closed valve period. The methodology is divided into
three steps: 1) a 1-zone chemical kinetic model (Chemkin Pro) is
used to determine either the intake conditions at IVC to achieve a
desired ignition timing or the ignition timing corresponding with
given IVC conditions, 2) the ignition timing and IVC conditions are
used as input parameters in a CFD model (Fluent 6.3) to calculate
the charge temperature profile and mass distribution prior to
autoignition, and 3) the temperature profile and mass distribution
are fed into a multi-zone chemical kinetic model (Chemkin Pro) to
determine the main combustion characteristics.
Different numbers of zones have been tested in the multi-zone
step to determine the effectiveness of the general methodology. 40
zones are needed to achieve acceptable thermal stratification
resolution to accurately predict peak heat release rates, peak
pressures rise rates and ringing intensity. However, a simplified
12-zone reduced model is developed and validated to study
combustion variables. Simulation results for the main combustion
variables and emissions are compared with experimental results from
a multi-cylinder HCCI engine fueled with biogas (60% CH₄ + 40%
CO₂), and operating at different intake conditions. Comparisons
between the proposed numerical methodology and experimental results
show good agreement for power output (measured as IMEPg), indicated
efficiency, burn duration, peak pressure, individual ringing
intensity, and HC and NOx emissions. CO emissions are
very sensitive to the input parameters of the 12-zone reduced
model. However, when the peak temperature after ignition of
boundary layer zones is properly handled; CO emissions are
reasonably well predicted. According to the results, the
methodology can successfully predict combustion parameters and
emissions for HCCI engines in which the fuel and air are well mixed
prior to ignition. Compared with previous sequential methodologies,
the method proposed here allows for reduced number of zones, more
uniform temperature profiles prior to ignition, more accurate
estimation of mass located in each zone, reduced computing time and
more accurate predictions of peak heat release rates, peak pressure
rise rates, and ringing intensity.
Citation: Bedoya, I., Cadavid, F., Saxena, S., Dibble, R. et al., "A Sequential Chemical Kinetics-CFD-Chemical Kinetics Methodology to Predict HCCI Combustion and Main Emissions," SAE Technical Paper 2012-01-1119, 2012, https://doi.org/10.4271/2012-01-1119. Download Citation
Author(s):
Ivan Dario Bedoya, Francisco Cadavid, Samveg Saxena, Robert Dibble, Salvador Aceves, Daniel Flowers
Affiliated:
University of Antioquia, Lawrence Berkeley National Laboratory, University of California, Berkeley, Lawrence Livermore National Lab
Pages: 17
Event:
SAE 2012 World Congress & Exhibition
ISSN:
0148-7191
e-ISSN:
2688-3627
Also in:
Kinetically Controlled IC Combustion, 2012-SP-2332
Related Topics:
HCCI engines
Ignition timing
Carbon monoxide
Combustion and combustion processes
Computational fluid dynamics
Emissions
Simulation and modeling
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