Study of Soot Generation in Hybrid Engines during Cold Start and Low-Load Conditions Using an Optical Engine SAIC GM Wuling Automobile Company, Limited

Format:

Book

Conference/Event

Author/Creator:

Liu, Changye, author.

Contributor:

Cui, Mingli

Li, Xuesong

Liang, Yuanfei

Man, Xingjia

Wang, Shangning

Conference Name:

SAE 2024 Vehicle Powertrain Diversification Technology Forum (2024-12-06 : Xi'An, China)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2025

Summary:

As regulations regarding vehicle emissions and fuel consumption become increasingly stringent, the development of hybrid power systems is accelerating, primarily due to their benefits in fuel efficiency and reduction of pollutants. Hybrid engines are specially designed to operate optimally at mid to high speeds and loads. But for low-speed low-load conditions, due to the relatively low in-cylinder tumble intensity and lower injection pressure, the fuel-air mixture tends to deteriorate, resulting in an increase in particle number. To enable the engine to reach optimal RPM and load quickly during frequent start-stop cycles, hybrid engines typically set a higher startup engine speed and establish fuel rail pressure more quickly compared to traditional engines. Yet hybrid engines still encounter challenges of soot generation during cold start conditions. Especially in urban driving conditions where the hybrid engine frequently experiences startups and idling, the soot generation problem becomes severe. Understanding the soot generation process under these specific conditions is critical for hybrid engines. This research aims to investigate soot formation process during cold-start and low-speed low-load conditions by examining the in-cylinder spray development and combustion processes. To achieve this, an optical engine has been employed, designed with a combustion system indentical to that of a cutting-edge hybrid engine. Backlit imaging method was used to capture the movement of spray droplets, which provides a clear visualization of how the fuel interacts with the piston top and in-cylinder airflow. High-speed color photography was used to record the flame propagation process and the sooty flame development from the bottom of the combustion chamber. By focusing on these processes, this research finds that for low-speed low-load conditions, the combustion of fuel film, which generates pool fire, is the main source of carbon soot. While for cold-start conditions, combustion of rich pockets in the chamber space is the primary source of soot. Insights gained from this research could inform the design of more efficient hybrid engines that minimize soot emissions, ultimately contributing to cleaner air and more sustainable transportation solutions

Notes:

Vendor supplied data

Publisher Number:

2025-01-7047

Access Restriction:

Restricted for use by site license