COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF NOx REDUCTION BY AMMONIA INJECTION IN THE MAN B&W 7S50MC MARINE ENGINE

Abstract

Taking into account the importance of NOx (nitrogen oxides) emissions from marine engines and the current increasingly restrictive legislation, this work aims to develop a numerical model to study NOx reduction. To this end, direct injection of NH3 (ammonia) into the combustion chamber was proposed in the MAN B&W 7S50MC marine engine. The numerical model was employed to analyze several injection temperatures, injection timings and ammonia to fuel ratios, obtaining NOx reductions of almost 60%. Besides, a comparison between ammonia injection and water injection was done. The results showed that ammonia is more efficient than water to reduce NOx with a negligible influence on other pollutants such as CO (carbon monoxide) and HC (hydrocarbons). Nevertheless, ammonia is efficient in a very restrictive temperature and injection timing range. This numerical model was compared with experimental measurements, obtaining satisfactory results which validate the work.