TITLE:
Controlled End-Gas Autoignition Effect on Pollutant Emissions of Ultra-High Efficiency Heavy-Duty Natural Gas Engine
AUTHORS:
Juan Felipe Rodriguez, Nestor Y. Rojas, Bret Windom, Daniel Olsen
KEYWORDS:
Heavy-Duty Engine, Natural Gas, Auto-Ignition, Knock
JOURNAL NAME:
Journal of Power and Energy Engineering,
Vol.14 No.10,
October
29,
2026
ABSTRACT: Heavy-duty on-highway natural gas (NG) engines present a promising alternative to diesel engines for reducing greenhouse gas emissions and harmful pollutants, provided their limitations—such as knock and misfire—are addressed to achieve diesel-like efficiencies. This study examines the impact of induced controlled end-gas autoignition (C-EGAI) on pollutant emissions in a high-efficiency, stoichiometric, spark-ignited (SI) natural gas engine. C-EGAI is employed as a combustion control strategy to enhance efficiency. Experiments were conducted using a single-cylinder heavy-duty engine designed to replicate the operation of an on-highway multi-cylinder engine. Exhaust gas recirculation (EGR) tests were carried out with a custom EGR system that simulates a high-pressure EGR loop, covering rates from 0% to 35%. A newly developed high compression ratio piston design was implemented to improve brake thermal efficiency (BTE) and mitigate knock tendencies. Measurements were taken under varying EGR rates and indicated mean effective pressures (IMEP). The results demonstrate that achieving C-EGAI conditions correlates with low engine-out emissions of nitrogen oxides (NOx), total hydrocarbons (THC), volatile organic compounds (VOC), and carbon monoxide (CO). These emissions were observed during high-load operation while attaining diesel-like BTE levels up to of 46%, using an EGR rate of 29.4%, and with f-EGAI of 28.5%.