Numerical simulation and spray model development of liquid ammonia injection under diesel-engine conditions

• Published in: Energy (Oxford) 2024-05, Vol.294, p.130833, Article 130833
• Main Authors: Zhang, Junqing, Chen, Danan, Lai, Shini, Li, Jun, Huang, Hongyu, Kobayashi, Noriyuki
• Format: Article
• Language: English
• Subjects: 0D spray model; alternative fuels; ambient pressure; ambient temperature; ammonia; carbon; combustion efficiency; Diesel engine; energy; internal combustion engines; Large eddy simulation; Liquid ammonia injection; liquids; mathematical models; phase transition; prediction; Spray characteristics; vapors
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2024.130833

Ammonia is regarded as a promising alternative fuel in internal combustion engine for its potential to reduce carbon emissions. Injection process of liquid ammonia will affect air-fuel mixture distribution and therefore combustion efficiency and NOx emissions. However, the experimental studies of liquid ammonia injection under engine conditions are limited, and the key impact factors of spray evolution are still unclear. This study aims to evaluate the applicability of numerical models for liquid ammonia spray, and numerically investigate spray characteristics under diesel-engine conditions (ambient temperature > 800K, ambient pressure > 2 MPa). Large eddy simulation coupled with Lagrangian particle tracking method were conducted, and the results show that the non equilibrium - Frössling phase change model coupled with Schiller-Naumann drag model can provide a good prediction of spray penetration. Liquid penetration increases with ambient pressure decreasing; vapor penetration increases with ambient density decreasing, but insensitive to ambient temperature. Temperature - mixture fraction distribution is sensitive to ambient temperature and superheat degree. Besides, a three-stage 0D model of spray tip penetration under diesel-engine conditions is developed firstly, which can reflect the key impact factors of ammonia spray evolution and provide theoretical support to optimize fuel injection strategy of liquid ammonia-fueled engines. •Liquid ammonia spray characteristics were numerically investigated using LES-LPT.•Non equilibrium - Frössling phase change model predicted spray penetration well.•A quadratic function of temperature - mixture fraction distribution was established.•Ammonia spray evolution under diesel-engine conditions was divided into three stages.•0D model of ammonia spray penetration under diesel-engine conditions was developed.