Ammonia Dispersion in Port Environments: A Comparative Study of LES-CFD and Integral Models

Abstract

Ammonia is a promising carbon-free fuel for maritime decarbonization. However, its inherent toxicity means accidental leaks during port operations can lead to severe consequences. Accurately assessing its dispersion behavior following accidental leaks is crucial. The complex port layouts significantly influence ammonia dispersion, posing a challenge for the accurate prediction by integral models. Furthermore, high-accuracy CFD studies based on the LES method for ammonia- fueled vessel leaks in port layouts are limited. Therefore, this study systematically evaluates the performance of LES-based CFD and integral models in predicting ammonia dispersion within port layouts. Firstly, the models were validated against three INERIS experimental trials using statistical metrics such as factor-of-two (FAC2), geometric mean bias (MG), and geometric variance (VG). Secondly, the validated CFD method was applied to simulate ammonia leakage from a vessel in a realistic port layout (Gamcheon Port, Busan) under two typical wind directions (140° and 250°). Finally, the predictive differences between integral models and CFD in the realistic port layout were systematically compared. Results showed that port buildings significantly altered dispersion patterns; compared to the 140° wind condition, the 250° downwind building cluster caused greater lateral spread and irregular concentration distributions. Integral models consistently overestimated concentrations downwind of the building cluster. Therefore, for scenarios with dense obstacles, integral models may require coupled analysis with CFD.