CFD-Assisted Design of an NH3/H2 Combustion Chamber Based on the Rich–Quench–Lean Concept

Abstract

Ammonia (NH3) and hydrogen (H2) are considered promising fuels for the power sector’s decarbonization. Their combustion is capable of producing energy with zero direct CO2 emissions, and ammonia can act as a stable energy H2 carrier. This study numerically investigates the design and implementation of staged combustion of a mixture of NH3/H2 by means of CFD simulations. The investigation employed the single-phase flow RANS governing equations and the eddy dissipation concept (EDC) combustion model, with the incorporation of a detailed kinetic mechanism. The combustion chamber operates under the RQL (rich–quench–lean) combustion regime. The first stage operates under rich conditions, firing mixtures of ammonia in air, enriched by hydrogen (H2) to enhance combustion properties in a swirl and bluff-body stabilized burner. The secondary stage injects additional air and hydrogen to mitigate unburnt ammonia and NOx emissions. Simulations of the first stage were performed for a thermal input ranging from 4 kW to 8 kW and flames with an equivalence ratio of 1.2. In the second stage, additional hydrogen is injected with a thermal input of either 1 kW or 2 KW, and air is added to adjust the global equivalence ratio to 0.6.