Impact of Exhaust Gas Recirculation (EGR) on the Emission of the Dual-Fuel Diesel Engine with Hydrogen as a Secondary Fuel

Hydrogen is one of the best alternatives for conventional fuels because it is free from carbon. Hydrogen has its own benefits and limitations in its use as a conventional fuel in automotive engine system. However, hydrogen increases the performance along with NOx formation. One of the methods to reduce NOx without comprising its performance is addition of exhaust gas recirculation (EGR). In the present investigation, the formation of carbon monoxide (CO), carbon dioxide (CO2), un-burnt hydrocarbon (HC) and oxides of nitrogen (NOx) was measured on four-cylinder water-cooled turbocharged direct ignition (DI) compression ignition diesel engine with diesel as a base fuel and hydrogen as a gaseous fuel (0–5%) by using EGR technique (5–10%) at various load conditions. The formation of NOx gets decreased by 37.82, 48.29 and 75.95% by using 5%, 10% and 15% EGR, respectively, at 40% load conditions as compared with pure diesel operation. Similarly, as the engine runs on dual-fuel modes with 5% substitutions of diesel fuel with hydrogen fuel (H2), the formation of NOx gets decreased by 21.16 and 29.90%, at 40% load conditions by using 5 and 10% EGR, respectively, as compared to pure diesel operation. Further, the formation of CO, CO2 and HC also gets decreased by the addition of 5% EGR in the gaseous–air mixture, while it increases beyond 5% EGR in dual-fuel mode conditions. The maximum quantity of the hydrogen and EGR substitution is limited due to knock in the engine. © 2021, The Institution of Engineers (India).