Session: 17-01 Industrial & Cogeneration

Paper Number: 151297

Exploration of Exhaust Gas Recirculation for Improved Carbon Capture System Performance on a 3.5 MWe Liquid-Fueled Gas Turbine 

As part of its Climate Action 2030 plan, the Navy has set ambitious carbon emission reduction goals that require the decarbonization of its vessel propulsion systems. Liquid-fueled gas turbines are the core of power generation for propulsion and auxiliary systems for much of the Navy’s fleet, due to their propensity for mission readiness, unlike modern alternative fuel systems. It is for this reason that the Navy has begun to pursue onboard carbon capture strategies (CCS) that would ordinarily be size-prohibitive, if not paired with high-fraction exhaust gas recirculation (EGR) systems. EGR systems for gas-turbine engines work by reintroducing a controlled amount of cooled, dried exhaust gas (primarily consisting of N2, O2 and CO2) back into the engine intake, displacing a portion of the incoming air. EGR increases the carbon concentration in the exhaust (e.g., 50% EGR doubles the exhaust CO2 concentration), thus enhancing the carbon extraction efficiency of the onboard CCS and reducing its power and footprint requirements.  
This work discusses the design and deployment implications of an EGR system on a 3.5 MWe Solar Turbines Centaur 40 gas-turbine. System requirements and design considerations of a gas-turbine EGR system are presented, along with detailed analysis of (1) a proposed EGR/intake air mixer and (2) a reduced-cost bottled gas manifold that will serve as a surrogate to an EGR system on Colorado State University’s full-size Centaur 40 engine. 
To maximize mixing performance of the intake air and the recirculated exhaust gases, several mixer designs were developed and assessed using Computational Fluid Dynamics (CFD) simulations. Mixing performance in the simulations was evaluated using the spatially resolved Coefficient of Variance (COV) of CO2 concentration in the engine intake. Results indicated that the method of EGR injection is equally as important as the physical geometry of an in-duct static mixer. While minor geometric adjustments had minimal impact on mixing effectiveness, the quantity and placement of injectors had the most significant impact. 
The envisioned EGR system and lab-based surrogate gas manifold was designed and evaluated using Flownex: a flow and heat transfer simulation software. Simulation results informed component sizing and the estimated power consumption for both a complete EGR and surrogate EGR system. The surrogate EGR apparatus was designed with vaporization, mixing, and flow control capabilities to imitate a true exhaust gas composition prior to injection into engine intake. This research enables improved decarbonization technologies without sacrificing current gas-turbine infrastructure. Successful EGR implementation will allow for retrofitting of existing systems to improve CCS performance and lower emissions. This preliminary analysis informs future full scale EGR testing on gas-turbines.

Presenting Author: Bianca Jeremiah Colorado State University

Presenting Author Biography: Bianca Jeremiah is a second-year master’s student studying mechanical engineering at Colorado State University, specializing in decarbonization and clean energy technologies. She earned her bachelor’s degree in mechanical engineering from Rowan University, where she also minored in physics and music and received a certificate in automotive engineering. During her undergraduate career, Bianca played a key leadership role in Rowan University’s Society of Automotive Engineers (SAE) chapter and attended the Baja SAE competition series as the transmission system lead. At CSU, she continues to engage with the academic community as the president of the Mechanical Engineering Graduate Association. Her current research focuses on Exhaust Gas Recirculation (EGR) applications for gas-turbines, aiming to contribute to cleaner, more efficient energy systems.

Andrew Harrod is a graduate student researcher at Colorado State University. He conducts research at the Powerhouse Energy Institute, focusing on advancing clean energy solutions at a global scale. He earned his undergraduate degree from CSU and transitioned into the university’s accelerated master's program. During his undergraduate studies, Andrew actively contributed to several research projects at the Powerhouse Energy Institute and served as vice president of the American Institute of Aeronautics and Astronautics' design build fly team. His current research focuses on reducing the carbon emissions of combustion engines as part of broader efforts to decarbonize the energy sector.

Authors:

Bianca Jeremiah Colorado State University
Andrew Harrod Colorado State University
Andrew Zdanowicz Colorado State University
Toluwalase Fosudo Colorado State University
Bret Windom Colorado State University