Numerical assessment of emergency ammonia underwater discharge from a platform supply vessel

Abstract For reaching the target of clean fuels in the Maritime sector, the use of ammonia as shipping fuel is a potential candidate as it is a zero-carbon fuel. In view of this, the necessity of a thorough study with respect to the emergency release of fuel ammonia on a ship is eminent, as there is a scarcity of research on emergency ammonia release underwater. Computational Fluid Dynamics (CFD) is a powerful tool for numerical prediction of the diffusion of a substance in the vicinity or greater area of the release, and is also able to handle multiphase flows. In this work CFD is used to simulate the time dependent 3D spatial distribution and concentration of ammonia when released underwater from a platform supply vessel considering parameters such as the positioning and size of the underwater vent, the ammonia mass transfer rate, the ammonia mean bubble diameter, the direction and intensity of the seawater current. Results show that if the ship maintains its steering maneuvering capability in case of an emergency scenario, then it is feasible to maintain a safe side in the opposite direction of the discharge location with minimum effect of toxic ammonia presence by positioning the ship axis parallel to the seawater current.