Session: Student Poster Competition

Submission Number: 186354

Multispecies Measurements and Chemical Kinetic Modeling of Ammonia–natural Gas Fuel Blends at Gas Turbine Operating Conditions 

Fossil fuel combustion has powered the global economy for over a century, with natural gas (NG) gradually replacing coal as a cleaner-burning alternative. Despite its advantages, NG combustion still produces carbon dioxide (CO₂), prompting interest in low-carbon fuels such as ammonia (NH₃). Ammonia offers carbon-free combustion and compatibility with existing infrastructure, making it a promising candidate for sustainable energy systems. However, its poor combustion characteristics and low flame speed hinder standalone use in combustion applications. Blending NH₃ with NG improves ignition and flame stability, enabling its use in gas turbines and internal combustion engines. NH₃ also shows potential in dual-fuel strategies with reactive fuels like hydrogen, enhancing flame stability and reducing emissions. Despite its promise, ammonia combustion presents challenges including blowout, incomplete burning, and NO_x formation. Furthermore, prior investigations have been confined to lower pressure regimes.

In response to these deficiencies, the current work applies laser absorption spectroscopy (LAS) in conjunction with shock tube experiments to probe the chemical kinetics and species evolution of NH₃/NG mixtures under conditions of elevated temperature and pressure. Through time-resolved diagnostics, the principal oxidation and decomposition pathways are elucidated, thereby informing the rational design and optimization of advanced low-carbon combustion systems.

Experiments were conducted in the University of Central Florida's High Pressure Extreme Range Shock Tube for Advanced Research (HiPER-STAR) facility. Fuel mixtures, calculated from stoichiometric mole fractions and diluted with argon, were uniformly premixed in a magnetically stirred high-pressure tank. Experiments examined stoichiometric ratio (φ = 1.2) mixtures at temperatures of 1660–1800 K and 5 bar. Time-resolved laser absorption spectroscopy (LAS) monitored key species (NH₃, H₂O, CO, NO, and CO₂) using five Quantum Cascade Lasers (QCLs) targeting mid-infrared absorption lines, while a Helium-Neon laser detected CH₄. These measurements yielded sub-microsecond temporal resolution and species-specific concentration profiles under precisely controlled temperature and pressure conditions, enabling accurate kinetic modeling.

The mechanism demonstrates strong predictive capability for global reactivity and major stable products, accurately capturing final H₂O and CO₂ concentrations and the temperature-dependent consumption of CH₄ and NH₃. However, it consistently overestimates CO formation by approximately 50–60% across all conditions, indicating the need for refinement of CO-related pathways. Overall, the model provides a reliable foundation for kinetic analysis but requires targeted improvements to enhance accuracy in intermediate species prediction.

Presenting Author: Bright Katey University of Central Florida

Presenting Author Biography: Graduate Research Assistant at Vasu Labs, University of Central Florida
I specialize in combustion science and laser diagnostics, with a focus on shock tube experiments and laser absorption spectroscopy (LAS) for speciation analysis. My work advances understanding of high-temperature chemical kinetics and supports the development of cleaner, more efficient energy solutions.
Passionate about leveraging optical diagnostic techniques to validate chemical mechanisms, I aim to drive innovation in sustainable combustion technologies. With expertise in experimental design, data analysis, and modeling, I strive to bridge experimental insights with computational approaches to improve predictive models for energy and propulsion systems.

Authors:

Bright Katey University of Central Florida
Zachary Morris University of Central Florida
Louis Vest University of Central Florida
Diego Pena University of Central Florida
Lucas Pitts University of Central Florida
Jonathan Mcgaunn University of Central Florida
Esteban Rodriguez University of Central Florida
Farhan Arafin University of Central Florida
Michael Pierro University of Central Florida
Justin Urso University of Central Florida
Ramees K. Rahman University of Central Florida
Subith Vasu University of Central Florida
Gregory Vogel PSM - Power Systems Mfg.