Influence of small amount of hydrogen fuel on spark-ignition engine characteristics through H-CNG fuel blend and its comparative study

ABSTRACT An experimental study was performed on single-cylinder, four-stroke, and spark ignition engines to understand the impact of a small quantity of hydrogen fractions in CNG fuel on an engine’s performance and emission characteristics. The two blends of H-CNG in which hydrogen fuel was used were 0.20 kg/hr and 0.25 kg/hr mass flow rate at varying engine rpm. The hydrogen enrichment increases the BTE by 3.54% and 4.94%, for HCNG (0.20 kg/hr) and HCNG (0.25 kg/hr), relative to CNG operation. Similarly, the hydrogen enrichment reduces the BSFC with higher margin due to its increment in calorific value compared to CNG operation. The H-CNG fuel blend has shown severe decrement in HC, CO, CO2, and O2 emissions compared to gasoline and CNG fuel. However, NOx emissions were a concern in CNG-fueled engine. The CNG-fueled engine has produced almost 32% of higher NOx emissions than gasoline. However, adding H2 fuel to CNG decreased NOx emissions and brought it nearly equal to the gasoline-fueled engine emissions at overall engine rpm. Overall, from a future perspective, the H-CNG mode of operation with optimum proportion of Hydrogen-CNG can be considered a suitable fuel blend to control engine emissions without compromising engine performance of conventional SI engines.