Table 1.
Compositions of Different Fuels Used in This Studya
| Compound | unit | CNG | RNG 1 | RNG 2 |
|---|---|---|---|---|
| Methane | % | 91.2% ± 0.8% | 93.5% ± 1.3% | 93.3% ± 0.6% |
| Ethane | % | 5.41% ± 0.18% | 1.50% ± 0.05% | 0.42% ± 0.01% |
| Propane | % | 0.33% ± 0.06% | 0.09% ± 0.02% | 0.03% ± 0.00% |
| Carbon dioxide | % | 0.82% ± 0.09% | 1.85% ± 0.39% | 4.28% ± 0.18% |
| Nitrogen | % | 1.83% ± 0.65% | 2.64% ± 1.01% | 1.77% ± 0.48% |
| Oxygen | % | 0.42% ± 0.30% | 0.42% ± 0.11% | 0.18% ± 0.04% |
| Aromatic hydrocarbons | ppm | 1.84 ± 0.24 | 1.73 ± 0.07 | 1.27 ± 0.12 |
| Other hydrocarbons | ppm | 7.04 ± 0.59 | 9.44 ± 2.23 | 5.11 ± 1.07 |
| Sulfur-containing compounds | ppm | 1.11 ± 0.18 | 1.95 ± 0.55 | 1.96 ± 0.36 |
| Higher heating value | MJ·m−3 | 38.27 ± 0.34 | 36.31 ± 0.47 | 35.46 ± 0.22 |
| Stoichiometric air/fuel ratio | kg/kg | 16.21 ± 0.15 | 15.67 ± 0.22 | 14.94 ± 0.10 |
a
Concentration of methane, ethane, propane, carbon dioxide, nitrogen, and oxygen are reported in percentage (with 1 standard deviation). Concentration of different hydrocarbons and sulfur-containing compounds are reported in ppm by volume (with 1 standard deviation). Fuel higher heating value and stoichiometric air/fuel ratios are calculated based on the measured major compounds (%) listed in this table.