There is growing demand for energy utilization due to stricter environmental emission norms to reduce greenhouse gases and other threats posed due to the emissions are major motivation factors for researchers to adopt on strategic plans to decrease the usage of energy and reduce the carbon contents of fuels, the usage of hydrogen or blend of hydrogen with CNG as a fuel in internal combustion engines is the best option. As hydrogen has lower volumetric energy density and higher combustion temperature, pure hydrogen-fueled engines produce lower power output and much higher NOx emissions than gasoline-fueled engine at stoichiometric air-fuel ratio. Blending of hydrogen with CNG provides a blended gas termed as hydrogen-enriched natural gas (hCNG). hCNG stands for hydrogen enriched compressed natural gas and it combines the advantages of both hydrogen and methane. The addition of Hydrogen to CNG has potential to even lower the CNG emissions and is the first step towards promotion of a Hydrogen economy. hCNG allows customers early hydrogen deployment with nearly commercial technology. Spark ignition Engines can be calibrated for lower NOx and greenhouse gas emissions. Spark ignition engine is compatible to run on hCNG with minimum modifications.
In the present study 395cc water cooled spark ignition engine with port fuel injection system was used to explore CNG and hCNG fuel with 18% Hydrogen in CNG for comparing engine performance and effective way to reduce emissions. A series of experiments were carried out on engine test dynamometer also on vehicle chassis dynamometer on 3-wheeler vehicles with different ignition timing, operating lambda. Hydrogen with CNG as a fuel in SI engines has shown significant positive impact on efficiency with lean lambda limits.
With 18% Hydrogen in CNG make it possible to run the engine leaner, resulting in lower emission for CO2, CO, HC however with higher NOx emissions. To reduce NOx emission on engine, novel water injection technology added on engine to reduce NOx emission by 43%. Experimental study on vehicle infers emission reduction on Indian driving cycle, also reduction in CO2 emission has shown improvement in fuel consumption of vehicle on driving cycle with lean lambda, retarded ignition timing with 18% percentage of Hydrogen blended with CNG.
Spark ignition engine with 18% Hydrogen in CNG fuel on three-wheel vehicle met Bharat Stage 6 emission norms. Emission result infers 41% margin in CO, 15% margin in NOx, 45% margin in HC+NOx and 9% improvement in CO2 emission which resulted in 10% improvement in fuel economy with hCNG when compare with CNG fuel. Finally, it has been said that hCNG fuels is next alternate fuel with the use of hydrogen in future vehicle fuel.