Lower carbon to Hydrogen ratio of CNG makes it a cleaner fuel, due to this CNG is gaining popularity as an Internal Combustion (IC) engine fuel in transport sector. Hydrogen fuel for IC engines is also being considered as a future fuel due to its simple carbonless structure. But several obstacles have to overcome before commercialization of H2 as an IC engine fuel for transport sector.
Hydrogen & CNG blends may be considered as an automotive fuel without any major modification in the existing SI engines. The Present work is undertaken to demonstrate the viability of HCNG as an automotive fuel. A passenger car fitted with a 4 cylinder, 1.3 liter, SI engine has been used in the present investigation. A sequential gas injection system has been developed to avoid the risk of back firing. The effect of gas pressure and gas temperature on the duration gas injection has been considered in the control strategy. In the first phase the duration of injection, ignition timing were optimized using CNG, subsequently 18% Hydrogen by volume was mixed in CNG and used in the present investigation.
Different parameters like injector pulse width and ignition timing were optimized under idling and different load conditions. Detailed testing has been conducted on idling operation to analyse the idle stability and emission. Subsequently vehicle mass emission tests were conducted on chassis dynamometer with CNG and HCNG fuel.
Test results indicate that COV in engine idle speed has been reduced from 1.1% to 0.5% with HCNG fuel as compared to CNG. CO emission has been reduced from 198 ppm to 15 ppm with HCNG as compared to Gasoline operation. HC emission has been also reduced from 67 ppm to 25 ppm with HCNG fuel as compared to gasoline. With HCNG mode NOx has increased significantly as compared to CNG mode. However, NOx was reduced by retarding the ignition timing by 30 crank angle with HCNG as compared to CNG operation during idling. CO2 is reduced by 19.47% with CNG as compared to gasoline and 31.74 % with HCNG as compared to gasoline during idling operation. During mass emission test CO, CO2 and HC were reduced with HCNG operation with respect to CNG operation The driveability with HCNG fuel was observed to be fairly good.