Session: 04-40: Emissions III

Paper Number: 153086

Evaluation of Combustion Models and Reaction Mechanisms to Predict NOx and CO Emissions From Densely Distributed Lean-Premixed Multi-Nozzle CH4/H2/Air Flames 

With global initiatives to reduce CO2 emissions, several new designs of gas turbine combustors that can operate with higher hydrogen content are being explored. Computational Fluid Dynamics simulation (CFD) has been an integral part of the design process of Gas Turbines. However, with an increased focus on design for fuel blends with high hydrogen content and in the absence of sufficient experimental or historical design data availability, the importance of CFD simulations is becoming increasingly critical. Predictive CFD simulations can provide significant insights into combustion behavior. The accuracy of simulations depends upon factors such as combustion models, reaction mechanisms, mesh resolution, etc. Most of the simulation methodologies developed in the past were focused on hydrocarbon fuels. Researchers have started focusing on simulation workflows for hydrogen fuels, considering lab-scale burners. Scale-up of these studies for complex industrial cases is required to develop methodologies that can be deployed for the industrial Gas Turbine design process.

This work explores the sensitivity of reaction mechanisms and combustion models to predict the flame length and emission characteristics as a function of CH4/H2 blend variations, using complex multi-nozzle combustor configuration. For the study, both RANS and LES turbulence models are explored. Test data used for the analysis is taken from work published by KAIST University, U. Jin and K.T. Kim [1] on the investigation of combustion dynamics and NOx/CO emissions from lean-premixed multinozzle CH4/H2 blended flames. The combustion domain consists of densely distributed small-scale multi-tube injectors called Micromix nozzles. This setup provides insights into the collective behavior of small-scale multi-nozzle flames and resultant emission rates. Test data for different inlet compositions, keeping a thermal power condition of 78 kW, are considered for evaluation. Results from simulations for OH* chemiluminescence, OH concentrations, NOx, and CO emissions are compared against the test data. Reduce Model Fuel Library (MFL) mechanism with relevant NOx pathways along with Flamelet Generated Manifold (FGM) model found to predict the variation of flame length and emissions concentration with change in fuel composition reasonably well, compared to detailed chemistry combustion model as well as test data. 

[1] Ukhwa Jin, Kyu Tae Kim, “Influence of radial fuel staging on combustion instabilities and exhaust emissions from lean-premixed multi-element hydrogen/methane/air flames”, Combustion and Flame, Volume 242, 2022, 112184, ISSN 0010-2180, https://doi.org/10.1016/j.combustflame.2022.112184.

Presenting Author: Sourabh Shrivastava ANSYS Inc.

Presenting Author Biography: Mr. Sourabh Shrivastava has 16 years of experience in Industrial usage of Computational Fluid Dynamics, with a focus on reacting flow and heat transfer modeling of gas-turbine combustors, IC engines, industrial furnaces and connected hot components. Sourabh has developed multiple solutions for combustion and heat transfer modeling. Some of these are part of standard features within Ansys Fluent. Based on the developed models and workflows, he has around 26 publications in international conferences like ASME, SAE, and ILASS. He earned his master's degree in Mechanical Engineering (Thermal Science) from IIT Kharagpur in 2008. Since then, he has been a part of the Ansys ACE organization.

Authors:

Sourabh Shrivastava ANSYS Inc.
Kiyoung Jung Ansys Korea
Abhijit Patil Ansys Inc.
Ukhwa Jin Korea Advanced Institute of Science & Technology (KAIST)
Pravin Nakod Ansys Inc.
Kyu Tae Kim Korea Advanced Institute of Science & Technology (KAIST)
Jeongwo Lee Ansys Korea