Experimental assessment of the carbon dioxide and hydrocarbon emissions on a downsized spark ignition engine using 100% hydrogen fuel

Adopting zero-carbon fuels is a great solution for the environment. Still, it presents significant challenges in existing Internal Combustion Engine (ICE) platforms due to variations in operational regions and engine tunability. Hydrogen is an excellent substitute for existing Spark Ignition (SI) and Compression Ignition (CI) engines due to its wide range of operations and combustion properties. However, hydrogen as the main and only supply fuel poses some challenges, particularly in understanding the emissions, specifically the carbon dioxide (CO2) and hydrocarbon (HC) emissions that can still be generated due to lubricant introduced in the combustion chamber.

The study aimed to test the emissions of CO2 and HC using a fast emissions analyser that can capture a sample per 0.25 crank degree and correlate pressure with exhaust pressure to identify the delay time. The assessment includes load and air-to-fuel (AFR) ratio sweeps in both time and crank domains and a full evaluation of spike emissions over 200 cycles.

The study's main findings show that the average emissions of CO2 and HC do not exhibit any significant emissions at low and high loads, regardless of the operational AFR. The time analysis showed one to two HC emission spikes over 200 cycles, with an average value of 80 ppm. Finally, the study presents emissions standard deviations with the peak in-cylinder to correlate the engine's various emissions generation with the engine's performance.