Keywords

Turbine Cooling, Ammonia, Decarbonization, Cycle Modeling, Heat Exchanger, TMATS

Abstract

Ammonia has emerged as a promising aviation fuel due to its carbon-free emissions, well-established production methods, and transportation infrastructure. However, challenges with its slow chemical kinetics and low flame speed necessitate the partial cracking of Ammonia to introduce hydrogen as a combustion promoter. This study addresses these challenges by designing and optimizing a tube bank heat exchanger to transfer heat from the Cooled Cooling Air (CCA) of the High-Pressure Compressor (HPC) to the Ammonia stream, facilitating the necessary cracking. Preliminary heat transfer calculations indicate insufficient heat in the CCA to achieve cracking temperatures, prompting an alternative approach: splitting the Ammonia flow into two streams, with one undergoing cracking and the other bypassing the exchanger. This flow-splitting method minimizes the energy with the flow fraction being a catalyst dependent parameter. The heat exchanger design is optimized using entropy-based and energy-based approaches, with the entropy method showing the most promise. Results demonstrate a significant reduction in the remaining heat needed for cracking (73%) and a decrease in heat exchanger mass (84%) when comparing the best design to a baseline. Additionally, the study integrates the heat exchanger into an Ammonia-powered turbofan model using the TMATS library and Cantera in SIMULINK, analyzing key performance metrics such as thrust, specific energy consumption, and thermal efficiency. Three engine configurations— kerosene-powered, Ammonia-powered, and Ammonia-powered with Cooled Cooling Air—are compared, revealing the impact of Ammonia cracking on turbine cooling flow and overall engine performance. A Ru- K/CaO catalyst is considered for high-pressure Ammonia decomposition to further optimize the cracking process.

Completion Date

2025

Semester

Fall

Committee Chair

Kapat, Jayanta

Degree

Master of Science in Aerospace Engineering (M.S.A.E.)

College

College of Engineering and Computer Science

Department

Department of Mechanical and Aerospace Engineering

Format

PDF

Identifier

DP0029815

Document Type

Thesis

Campus Location

Orlando (Main) Campus

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