The Effect of Injection Timings on Performance and Emissions of Compressed Natural-Gas Direct Injection Engine

Table 3

Typical composition (Vol.%) of CNG (source: PETRONAS Research & Scientific Services).

Component	Symbol	Volumetric%
Methane	CH4	94.42
Ethane	C2H6	2.29
Propane	C3H8	0.03
Butane	C4H10	0.25
Carbon dioxide	CO2	0.57
Nitrogen	N2	0.44
Others	()	2.0