Research Article
The Effect of Injection Timings on Performance and Emissions of Compressed Natural-Gas Direct Injection Engine
Table 2
Combustion related properties of gasoline and CNG.
| | Properties | Gasoline | CNG |
| | Motor octane number | 80–90 | 120 | | Molar mass (g/Mol) | 110 | 16.04 | | Carbon weight fraction (mass%) | 87 | 75 | | (A/F)s | 14.7 | 17.23 | | Stoichiometric mixture density (kg/m3) | 1.38 | 1.24 | | Lower heating value (MJ/kg) | 43.6 | 47.377 | | Lower heating value of stoic. mixture (MJ/kg) | 2.83 | 2.72 | | Flammability limits (Vol% in air) | 1.3–7.1 | 5–15 | | Spontaneous ignition temperature (°C) | 480–550 | 645 |
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