A Pathway to Exceed 50% Indicated Thermal Efficiency for Gasoline Engines with Active Pre-Chamber Tongji University

Format:

Book

Conference/Event

Author/Creator:

Deng, Jun, author.

Lee, Hau Leung, author.

Miao, Xinke, author.

Xu, Bingxin, author.

Zhang, Jianqi, author.

Li, Liguang, author.

Conference Name:

WCX SAE World Congress Experience (2026-04-14 : Detroit, Michigan, United States)

Language:

English

Subjects (All):

Lean burn engines.

Combustion and combustion processes.

Nitrogen oxides.

Emissions control.

Engines.

Pressure.

Gasoline.

Emissions.

Logistics.

Local Subjects:

Lean burn engines.

Combustion and combustion processes.

Nitrogen oxides.

Emissions control.

Engines.

Pressure.

Gasoline.

Emissions.

Logistics.

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2026

Summary:

Research on high efficiency and low emission control strategies are crucial for addressing energy security and pollution challenges for combustion engines of vehicles. This paper investigates the effects of increasing the compression ratio and excess air coefficient (λ) in naturally aspirated engines via active pre-chamber technology, and further enhancing λ through the synergy of active pre-chamber with intake boosting and Miller cycle technology, on combustion efficiency and pollutant emissions. Experiments were conducted on a high-compression-ratio (up to 16.6) single-cylinder gasoline engine. Under natural aspiration, the effective compression ratio was raised via valve timing, while λ was increased using integrated passive and active pre-chamber systems. Under boosted conditions, intake flow was controlled via a flow meter, and λ was controlled via an active pre-chamber to analyze the λ distribution and thermal efficiency at high-efficiency operating points. Results indicate that under natural aspiration, increasing the effective compression ratio to 15.8 and λ to 1.4 improved the indicated thermal efficiency (ITE) to 40.3%. Further deployment of an active pre-chamber enabling ultra-lean combustion (λ=2.0) achieved an ITE of 43.3% while reducing NOx emissions to 5310-6. Under boosted intake pressure with Miller cycle, elevating intake pressure to 282kPa and achieving ultra-lean combustion (λ=2.02.2) resulted in ITE over 50%, with NOx emissions consistently below 5010-6 (ppm - parts per million)

Notes:

Vendor supplied data

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