Raw Emissions Determination and Calculations for Blended Fuel – HCNG

HCNG is hydrogen enrichment in Natural Gas and is stored in the pressurized form. The proportion of hydrogen typically varies from 5-30 of hydrogen in natural gas by volume percentage. Hydrogen is considered an imminent fuel due to the enormous potential of having a high energy yield (LHV – approx. 120 MJ/kg) and wide flammability range. HCNG can bridge the gap between Compressed Natural Gas (CNG) and hydrogen to enhance the usage of hydrogen by taking advantage of existing CNG infrastructure. This particular paper is written to vitrine the typical emission calculation for the HCNG-fueled engines. Further to this study, the stoichiometric combustion equation for HCNG and ugas constant is also determined. To check whether the engine emissions comply with the standard emissions regulations, the emissions gas Analyser readings (in ppm) are essential to convert into mass-specific emissions (g/kWh). Here, for the conversion calculations, the ‘Ratio between densities of gas component and exhaust gas’ (ugas) plays a vital role. This is a unique value which changes according to the fuel composition. ISO 8178 part 4 has provided the ugas coefficient for various conventional fuels. However, for specific emissions calculations of HCNG blends, this coefficient is not readily available. In this paper, we have calculated the ugas coefficients for various HCNG blends for emissions determination and provided a sample calculation to showcase the same. Keywords: HCNG, Raw Emission, Hydrogen, ugas Coefficient, Natural Gas