The Effect of EGR on Knock Suppression, Efficiency, and Emissions in a Stoichiometric, Spark Ignited, Natural Gas Engine

Conference · Tue Oct 15 04:00:00 EDT 2019

OSTI ID:1778113

Bayliff, Scott ^[1]; Marchese, Anthony; Windom, Bret; Olsen, Daniel

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1. Colorado State University

Exhaust gas recirculation (EGR) is widely employed on internal combustion engines for NOx reduction and knock suppression. In this study a comprehensive analysis was performed to determine the effect of EGR on efficiency, emissions, and knock suppression of stoichiometric, spark ignited, natural gas engines. Tests were conducted using a single cylinder, variable compression ratio, cooperative fuel research (CFR) engine at 900 RPM, engine load of 800 kPa indicated mean effective pressure (IMEP), and stoichiometric conditions. The tests were performed using a custom EGR system capable of providing a range of EGR displacement rates from 0% to 40% of the intake charge at engine power levels between 1.5 and 3.5 kW. The experimental measurements included the variance of EGR rate, compression ratio, boost pressure, and location of 50% mass fraction burned (CA50). CA50 was controlled with ignition timing using a Woodward Large Engine Control Module. The use of EGR was found to expand the knock limit, while reducing NOx emissions and increasing engine efficiency as much as 4.5% through increased compression ratio and power density. The highest EGR rate that demonstrated beneficial gains on the CFR engine was 23%; the optimal EGR rate was found to be 19%.

• Research Organization: Colorado State University
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Vehicle Technologies Office
• DOE Contract Number: EE0008331
• OSTI ID: 1778113
• Country of Publication: United States
• Language: English

Related Subjects

Cooperative Fuel Research Engine
Exhaust Gas Recirculation
Stoichiometric Natural Gas
Knocking Threshold