buletinul institutului politehnic din iaşi - Universitatea Tehnică ...

Bul. Inst. Polit. Iaşi, t. LVIII (LXII), f. 4, 2012 83
Zetec 2.0 L, I4 engine fuelled with hydrogen dedicatedly (Stockhausen et al.,
2002), (Tang et al., 2002).
Table 1
Hydrogen and gasoline properties
Property Hydrogen Gasoline
Molecular mass, kg/kmol 2.016 114
Density, kg/m 3 0.089 750
Theoretical air-fuel ratio, kg/kg comb 34.32 14.5
Flame velocity in air, m/s 2.37 0.12
Octane number >130 90…98
Auto-ignition temperature, K 850 750
Lower heating value, KJ/kg 119600 42690
Minimum ignition energy, mJ 0.018 0.25
Flammability limits in air, % 4…75 1…7.6
Laminar burning velocity in air, m/s 2…2.3 0.37…0.43
Normal boiling point temperature, K 20 310…478
Stoichiometric composition in air, % 29.5 1.65
Adiabatic flame temperature, K 2384 2270
Although fuel cells have better efficiency than hydrogen engines, the cost
of a hydrogen internal combustion engine is much less than a fuel cell and the
power system of a vehicle. To use hydrogen in an internal combustion engine,
some modifications have to be made but the working process is basically the
same. Some difficulties should be overcome before the engines go into a
common use, such as detonation, backfire and abnormal combustion (Jorach,
1997). By using a suitable mathematical model the performance of a hydrogen
engine can be simulated therefore it is possible to determine a beneficial
working range for optimizing and predicting the engine’s performance (Jie et
al., 2003).
Nowadays, the development of an internal combustion engine is based on
a close link between experimental engine testing and numerical simulation.
Multi-dimensional and one dimensional thermo-fluid dynamic models are
commonly used to optimize the engine design through the prediction of the
unsteady flows in the intake and exhaust systems (Onorati et al., 2007),
(Winterbone & Pearson, 2000), (Morel et al., 2003), (Montenegro et al., 2005),
(Onorati et al., 2004 a), (Onorati et al., 2004 b), and of the combustion and
emission formation processes in the cylinder (D’Errico et al., 2002), (D’Errico
& Lucchini, 2005), (D’Errico et al., 2008).
2. Processes Modelling
There are many numerical simulation models used and because it is less
expensive than experimental engine testing it is widely used in academic and