Numerical investigation of performance, combustion, and emission characteristics of spark-ignition engine fuelled with compressed natural gas and hydrogen

The combustion of gasoline engines running on blends of compressed natural gas and hydrogen fuels was investigated using the quasi-dimensional and two-zone model. This model could investigate and predict the combustion characteristics, emissions, and performance parameters of petrol engines using MATLAB software. The impact of hydrogen inclusion to compressed natural gas on the cylinder temperature, pressure, cumulative work done, and heat transfer related to compressed natural gas was investigated. The engine's thermal efficiency and output power were increased while specific fuel consumption was decreased when hydrogen was blended up to 20%. The highest decline in specific fuel consumption of 20% hydrogen was 25.1% for compressed natural gas. The torque values are 4.25, 4.34, 4.42, 4.51, and 4.60 N.m for compressed natural gas, hydrogen with compressed natural gas HCNG 5%, HCNG 10%, HCNG 15%, and HCNG 20%, respectively, at rated speed of 2500 r/min. The peak decreases in peak cylinder temperature and pressure for HCNG 20% compared to compressed natural gas are 5.9% and 5.2%, respectively. For HCNG 20%, the greatest cylinder pressure, temperature, and cumulative work done were 7.9 MPa, 2309.97 K, and 190.88 J, respectively. NOx emissions were increased for hydrogen-compressed natural gas blends but hydrocarbon emissions were decreased. In comparison to compressed natural gas, the highest hydrocarbon emission reduction is up to 2.64% for HCNG 20%. The model's validity was examined in comparison to the findings from the literature and the Diesel RK program. The results show that the MATLAB code is appropriate. Several alternative fuels can be used using this mathematical model.