Numerical Study on a Diesel–Hydrogen Dual‐Fuel Engine with Water Injection and Variable Compression Ratio

Abstract

In the near future, using engines for practical experimentation will likely not be a viable option for testing and research. During the previous trials, it was witnessed that increased knocking and appearance of NOx are problems in a diesel–hydrogen dual‐fuel engine. With hydrogen and diesel in dual‐fuel mode, combustion and performance are optimized, and the engine's fuel consumption is reduced. However, as a result, the flame propagates at a very high rate and the lean mixture operating limits remain extended, which allow for the reduced emission of NOx over conventional pilot fuel. To get rid of this scenario and completely understand the combustion process, a computational fluid dynamics model (sector model) is developed and simulated. The introduction of water injection (WI), and reducing the compression ratio, decreases the in‐cylinder temperature. The reduction of knocking is achieved by varying the compression ratio from 16.5 to 15.5:1 all at full‐load conditions. Results predict rise in in‐cylinder temperature at 8% hydrogen addition, which also increases knocking and NOx emissions. The higher cylinder temperature as well as its effects are reduced by the debut of WI and also by reducing the compression ratio in parallel.