9th International Engine Congress 2022 9th International Engine Congress Ignitability Study of a Spark-ignited Heavy-duty Engine, fueled with Natural Gas (CNG). :397-414

Engineering and Technology, Mechanical Engineering, Vehicle and Aerospace Engineering, Teknik, Maskinteknik, Farkost och rymdteknik, Energy Engineering, Energiteknik

The impact of different spark designs on the ignition and combustion stability is studied using a 13-liter CNG fueled heavy duty spark ignited engine to search for the “optimal” spark design. Experimental results show that robust ignition can be achieved using a significantly shorter spark duration and lower energy than expected. A capacitive discharge ignition (CDI) system enabled to separately control the available spark voltage, current and duration (FlexiSpark® CDI) was compared to a standard CDI system without spark control and an inductive discharge (IDI) ignition system. Typically, a robust ignition can be provided using only 5% of the spark duration and 17% of the spark energy compared to that required by an IDI system to accomplish an equivalent ignition and combustion stability. By applying control of the spark, a robust ignition can be provided which is optimized for the fuel, the engine design, the engine operating condition, and the condition of the spark plugs. This offers a potentialto significantly reduce the spark-plug wear and the total cost of ownership without compromising engine performance. The results are especially interesting in the view of Hydrogen fueled SI-ICE, where the required available spark voltage is high, but the required spark energy is low. It is desirable to use a spark design with just enough voltage and power to initiate a sustainable combustion, but with minimal energy not to excessively wear and heat the spark plug electrodes to avoid pre-ignition.