Numerical Study on Combustion and Emission Characteristics of a Liquid Ammonia Direct Injection Ammonia-Diesel Engine Tsinghua University

Format:

Book

Conference/Event

Author/Creator:

Liu, Yi, author.

Contributor:

Chen, Qingchu

Qi, Yunliang

Wang, Zhi

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:

Under the guidance of carbon neutrality goals, ammonia is expected to become a promising alternative fuel for internal combustion engines. Ammonia-diesel dual-fuel combustion not only effectively reduces carbon emissions but also addresses the issue of ammonia's slow combustion speed, ensuring good engine performance. Ammonia-diesel engines with liquid ammonia direct injection have the potential to further increase the ammonia energy ratio (AER) and reduce unburned ammonia, greenhouse gas (GHG) emissions, as well as NOx emissions. Based on a numerical model of a liquid ammonia direct injection ammonia-diesel engine, this paper compares two different injection system configurations: coaxial and non-coaxial liquid ammonia direct injection, and investigates the effect of AER on combustion and emission characteristics in the non-coaxial mode. The results show that, compared to the non-coaxial mode, the coaxial mode achieves more even fuel distribution and combustion distribution, higher indicated thermal efficiency (ITE), and lower emissions of unburned ammonia and N2O. However, NOx emissions increase significantly. In the non-coaxial mode, as the AER increases from 50% to 90% or higher, the unevenness of in-cylinder fuel distribution increases significantly. When AER reaches 95% or higher, more ammonia diffuses near the cylinder walls, where it is difficult to burn due to flame quenching, and the in-cylinder combustion temperature decreases, leading to an increase in unburned ammonia and N2O emissions. NOx emissions, on the other hand, decrease as AER increases. Liquid ammonia direct injection reduces in-cylinder temperature, helping to reduce heat loss, which becomes more pronounced as AER increases. However, in the cases of AER = 95% and 98%, the deterioration of in-cylinder combustion conditions leads to an increase in unburned ammonia and a decrease in combustion efficiency, resulting in a significant drop in ITE. The highest ITE occurs at AER = 90%, reaching 49.7%

Notes:

Vendor supplied data

Publisher Number:

2025-01-7118

Access Restriction:

Restricted for use by site license