TY - JOUR
T1 - Numerical investigation of diesel spray combustion characteristics in the ammonia/air atmosphere
AU - Wang, Xiaochen
AU - Bu, Han
AU - Chen, Hao
AU - Liu, Jinlong
AU - Chen, Zhenbin
AU - Gao, Jianbing
N1 - Publisher Copyright:
© 2024 Energy Institute
PY - 2024/10
Y1 - 2024/10
N2 - Ammonia/diesel dual-fuel combustion mode is a promising strategy for decarbonizing internal combustion engines. However, the impact of a premixed ammonia/air atmosphere on diesel spray combustion characteristics is not fully understood. This study analyzes the effects of premixed ammonia/air atmosphere, including premixed equivalence ratio, the cooling effect of liquid ammonia vaporization, and ambient oxygen concentration on the ignition and combustion characteristics and soot yield potential of diesel spray. Numerical simulations using n-heptane as a single-component diesel surrogate reveal that increasing the premixed ammonia equivalence ratio and lowering ambient oxygen concentration extend the ignition delay times and flame lift-off length of n-heptane spray. Liquid ammonia vaporization further prolongs the ignition delay by lowering the ambient temperature during n-heptane auto-ignition. Moreover, there is a trade-off between ignition delay and soot yield potential as longer ignition delays allow more thorough mixing of diesel and premixed gas, reducing soot formation. Given the substantial extension of ignition delay in ammonia/air atmospheres, it is recommended that ammonia/diesel dual-fuel engines operate with higher charged gas temperatures to ensure stable and repeatable ignition events. The negative effects of increased soot yield could be mitigated by using ammonia to reduce soot precursors. Overall, these results underline the need for further fundamental studies on ammonia/diesel co-combustion to facilitate the commercial adoption of ammonia/diesel dual-fuel engines.
AB - Ammonia/diesel dual-fuel combustion mode is a promising strategy for decarbonizing internal combustion engines. However, the impact of a premixed ammonia/air atmosphere on diesel spray combustion characteristics is not fully understood. This study analyzes the effects of premixed ammonia/air atmosphere, including premixed equivalence ratio, the cooling effect of liquid ammonia vaporization, and ambient oxygen concentration on the ignition and combustion characteristics and soot yield potential of diesel spray. Numerical simulations using n-heptane as a single-component diesel surrogate reveal that increasing the premixed ammonia equivalence ratio and lowering ambient oxygen concentration extend the ignition delay times and flame lift-off length of n-heptane spray. Liquid ammonia vaporization further prolongs the ignition delay by lowering the ambient temperature during n-heptane auto-ignition. Moreover, there is a trade-off between ignition delay and soot yield potential as longer ignition delays allow more thorough mixing of diesel and premixed gas, reducing soot formation. Given the substantial extension of ignition delay in ammonia/air atmospheres, it is recommended that ammonia/diesel dual-fuel engines operate with higher charged gas temperatures to ensure stable and repeatable ignition events. The negative effects of increased soot yield could be mitigated by using ammonia to reduce soot precursors. Overall, these results underline the need for further fundamental studies on ammonia/diesel co-combustion to facilitate the commercial adoption of ammonia/diesel dual-fuel engines.
KW - Ammonia/air environment
KW - Boundary conditions
KW - Combustion characteristics
KW - Diesel spray
KW - Numerical simulation
UR - http://www.scopus.com/inward/record.url?scp=85197495239&partnerID=8YFLogxK
U2 - 10.1016/j.joei.2024.101718
DO - 10.1016/j.joei.2024.101718
M3 - Article
AN - SCOPUS:85197495239
SN - 1743-9671
VL - 116
JO - Journal of the Energy Institute
JF - Journal of the Energy Institute
M1 - 101718
ER -