High-Speed Multiplexed Spatiotemporally Resolved Measurements of Exhaust Gas Recirculation Dynamics in a...

Area of Science:

• Internal Combustion Engine Technology
• Environmental Engineering
• Optical Diagnostics

Background:

• Reducing emissions and improving fuel efficiency in internal combustion (IC) engines is critical for transportation.
• Exhaust gas recirculation (EGR) is a key technology for lowering nitrogen oxide (NOx) emissions.
• Charge-gas non-uniformities in multi-cylinder engines hinder optimal EGR implementation, affecting performance and efficiency.

Purpose of the Study:

• To develop and demonstrate a real-time laser diagnostic system for analyzing spatiotemporal charge-gas distributions in IC engine intake manifolds.
• To precisely measure exhaust gas recirculation (EGR) fraction and non-uniformities.
• To provide data for optimizing EGR systems in advanced engine concepts like reactivity controlled compression ignition (RCCI).

Main Methods:

• An absorption-based laser diagnostic system was developed, tuned to a carbon dioxide (CO2) absorption band near 2.7 µm.
• The system simultaneously probed four locations within the intake manifold.
• EGR fraction was analyzed independently at speeds of 5 kHz (1.2 crank angle degree at 1k RPM) with high accuracy.

Main Results:

• The laser diagnostic successfully studied spatiotemporal EGR non-uniformities in real-time.
• High-speed, multi-point measurements of EGR distribution were achieved.
• Accurate quantification of EGR fraction at various engine operating conditions was demonstrated.

Conclusions:

• The developed laser diagnostic provides crucial insights into EGR non-uniformities within IC engine intake manifolds.
• This technology facilitates the fine control and optimization of EGR systems.
• It supports the development of more efficient, higher-performing, and environmentally friendly next-generation IC engines.