Research Projects

As a carbon-free energy carrier, ammonia (NH₃) has emerged as a promising alternative for power generation, offering high hydrogen density, zero carbon emissions during combustion, and compatibility with existing infrastructure. Ammonia is also relatively easy to store and handle, remaining liquid at moderate pressures (about 8 bar) and providing around 30% higher volumetric energy density than hydrogen. ammonia combustion faces several intrinsic challenges. These include low laminar flame speed (about 7 cm/s), high auto-ignition temperature (around 930 K), narrow flammability limits (16–25% vol. in air), and a high minimum ignition energy. These properties severely hinder flame propagation, ignition reliability, and combustion stability—especially in ultra-lean environments typical of modern gas turbines. Additionally, the presence of nitrogen in fuel molecule contributes to elevated NOₓ emissions and unburned NH₃ slip, raising both regulatory and operational concerns. The MILD (Moderate or Intense Low-oxygen Dilution) combustion regime offers a promising solution by enabling distributed, low-temperature combustion, which can mitigate thermal NOₓ formation and improve flame stability. However, the application of ammonia in such regimes remains insufficiently understood and requires detailed investigation under controlled conditions. This project will begin with the design and development of a lab-scale, non-premixed gas turbine combustor operating in the MILD regime. The power rating of the combustor will be up to 100 kW and it will be operated at moderate pressures up to 5 bar. The combustor will have geometrical features to create intense internal recirculation of the combustion products, leading to creation of highly-diluted and preheated environment in the combustor. Further, provisions for air preheating through recuperative heating will be provided. This will help attain MILD combustion for pure ammonia-air combustion at gas turbine relevant conditions. This test rig will serve as the experimental platform for analysing ammonia–air combustion stability and pollutant formation. The experimental study will be supported by high-fidelity computational fluid dynamics (CFD) simulations. Unsteady Reynolds-Averaged Navier–Stokes (URANS) modeling will be implemented using the Eddy Dissipation Concept (EDC) framework in ANSYS Fluent, coupled with detailed ammonia chemical kinetics (e.g., the Stagni mechanism) to resolve the turbulence–chemistry interactions, which has a significant role in determining the flame behaviour and pollutant formation. Design and development of the MILD combustor will be carried out through validation of numerical results against experimental measurements, in particular instability frequencies, temperature profiles, and NOₓ emissions. Through this integrated approach in this project, we will be able to understand better the pure ammonia-air combustion in MILD regimes for gas turbines operating conditions.