A comparative study on ammonia-air and ammonia-oxygen combustion in a gas turbine combustor: Flow/flame interactions and NOx emissions
Mohammed El-Adawy, Mohamed S. Hamdy, Medhat A. Nemitallah
Abstract
In this study, ammonia combustion was numerically investigated within a gas turbine combustor model to explore its potential for ammonia-based energy applications. The research specifically examined the impact of oxygen-enriched conditions, utilizing an oxidizer composed of 100 % oxygen, on flame behavior, temperature distribution, and NOx emission profiles across a range of equivalence ratios ( ϕ = 0.71.3). The results from both combustion environments of ammonia-oxygen (NH 3 /O 2 ) and ammonia-air (NH 3 /Air) were systematically compared in terms of combustion characteristics and NOx emissions. NH 3 /O 2 combustion demonstrated a markedly higher peak flame temperature of 2860 K compared to 2059 K for NH 3 /air combustion at ϕ = 1.0. NOx emissions are a major concern in both ammonia combustion systems, especially in ammonia oxy-combustion. In NH 3 /air combustion, the maximum NOx decreases from 4188 ppm at lean ( ϕ = 0.7) to 3015 ppm at ϕ = 1.0, and further to 1502 ppm under rich conditions ( ϕ = 1.3). In comparison, NH 3 /O 2 combustion yields much higher NOx levels, starting at 14054 ppm, over three times higher, then dropping to 8095 ppm and 2728 ppm at the same ϕ . These findings provide valuable insights into the combustion of ammonia, offering critical guidance for optimizing ammonia-fueled systems in future low-carbon energy applications.