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

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 O-2 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 H-2 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.

Automated summary

The experimental study found that adding hydrogen to CNG fuel can increase engine thermal efficiency, reduce fuel consumption, and significantly decrease emissions, especially carbon monoxide and nitrogen oxides. In the long term, hydrogen-CNG blend may be considered as a suitable engine fuel.