Abstract:
Hydrogen is a clean potential alternative fuel for internal combustion engines and
completely eliminates the carbon based engine emissions (CO, CO2 and unburned hydrocarbons).
Homogenous charge compression ignition (HCCI) is a low temperature combustion
mode with higher thermal efficiency and ultralow NOx emission. Hydrogen HCCI
engine can combine potential benefit of fuel and combustion characteristics. In HCCI engine,
combustion is governed by the chemical kinetics of the oxidation reactions. In-order
to find a suitable reaction mechanism to numerically predict the combustion characteristics
of hydrogen HCCI engine, 15 recent hydrogen combustion mechanisms are compared
and analyzed. All mechanisms were simulated using a stochastic reactor model (SRM) to
evaluate the combustion parameters for HCCI engine. Simulations were performed by
varying inlet temperature (400e440 K), intake pressure (1.0e3.0 bar), engine speed (1000
e3000 rpm) and relative air-fuel ratio (l ¼ 2 to 8) for all the mechanisms. Ignition delay
predicted from different mechanism was compared with experimental data and ignition
delay was also compared at engine like condition using all the test mechanisms. Error in
prediction of different combustion parameters such as start of combustion (CA10),
maximum cylinder pressure (Pmax) and maximum heat release rate (HRRmax) were
evaluated using different hydrogen combustion mechanisms. It was found that a recently
developed hydrogen mechanism (Maurya-2017) shows the closet resemblance with the
experimental cylinder pressure data. The Oconaire-2004 mechanism was able to accurately
predict the characteristics of hydrogen HCCI combustion. It was also found that
NUIG-NGM-2010 and CRECK-2014 mechanisms were able to estimate the HCCI combustion
characteristics under higher combustion temperature
