Ignitability Study of a Spark-ignited Heavy-duty Engine, fueled with Natural Gas (CNG)

Forskningsoutput: AvhandlingMasteruppsats

Sammanfattning

In-order to meet today’s stringent emission regulations of the European Union, the use of low-carbon fuels in ICE, for instance, Natural Gas (CNG)1 is on the limelight. Due to the high knock-resisting properties of methane (high octane rating), the SI (Spark-Ignition) combustion process is the best match with CNG1. A major disadvantage with an SI engine is its low thermal efficiency mainly due to the engine, being throttled. Hence, in-order to increase its efficiency, diluted air (by means of EGR) can be a promising solution.

However, with the addition of EGR, combustion stability degrades, hence indicating a potential need for high Ignitability. A robust ignition system can be a solution to achieve high combustion stability by discharging high spark current and duration at the spark-plug gap, therefore, an excessive waste of spark energy in the combustion chamber. As an impact, it will lead to increase in wear in the spark plug electrodes, which is not desirable. Therefore, an experimental research is performed in a heavy-duty SI-ICE fueled with Natural Gas, in-order to study the ignitability requirements of the engine to attain robust combustion, even with high dilution/EGR level.

Three different ignition systems are considered in the experiment: a conventional Inductive Discharge Ignition (IDI) system, a Standard Capacitive Discharge Ignition (CDI) system, and an optimized CDI system using FlexiSparkTM Ignition Control Module (ICM), developed by SEM AB. The experiments are performed at different engine operating conditions to review the ignitability requirements with the change in engine load and RPM while adding dilution (by means of EGR). After comparing multiple spark discharge parameters of the ignition systems with respect to engine performances, it is found that the most influential parameter that governs the ignitability capability of an ignition system is “Spark Power”. By effectively varying spark power, the engine can still achieve stable combustion with minimal spark duration. Therefore, a significant amount of spark energy can be saved from being wasted by optimizing the spark discharge parameters, hence keeping the spark plug electrodes wear to a minimum.

Finally, a best suitable spark design strategy is proposed for the ignition systems tested at different engine operating conditions while assuring minimal waste of both spark power and energy in the combustion chamber and maintaining a stable engine operation with high EGR/dilution level.
Originalspråkengelska
KvalifikationMaster
Tilldelande institution
  • HAN University of applied sciences
  • Förbränningsmotorer
Handledare
  • Lundgren, Marcus, handledare
  • Ängeby, Jakob, handledare, Extern person
  • Merts, Menno, handledare
Tilldelningsdatum2021 juli 7
StatusPublished - 2021 juli 7

Ämnesklassifikation (UKÄ)

  • Energiteknik
  • Annan maskinteknik

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