Session: 03-02 Ammonia as Fuel and Hydrogen Carrier – Combustion, Storage, and Safety II

Submission Number: 175617

Thermal Fluid Performance Analysis of Lattice Structures in an Ammonia Powered Turbofan Engine 

The need for decarbonization in the aviation industry has given rise to the use of cleaner fuels onboard, such as ammonia-hydrogen blend. This study proposes integrating a supercritical CO₂ Brayton cycle at the exhaust of a turbofan engine to recover waste heat for ammonia preconditioning, heating it to the cracking temperature required to produce hydrogen onboard. This novel idea of integrating ammonia cracking into a high-bypass, two-shaft turbofan engine, such as the one used in the Boeing 737 Max, solves the hydrogen storage issue while improving ammonia's combustion characteristics and minimizing NOx generation. 

This paper focuses on the design of a counterflow heat exchanger featuring a triply periodic minimal surface (TPMS) core for heat transfer between supercritical CO₂ and NH₃. TPMS geometries — characterized by high surface-area-to-volume ratios — exhibit excellent thermal performance. 

Computational simulations were conducted to investigate flow characteristics and evaluate heat transfer performance using experimental-scale flow rates for both fluids. The Computational Fluid Dynamics (CFD) analysis was split into two parts: core analysis and header maldistribution. This approach reduced the computational cost of the conjugate heat transfer (CHT) model, which couples CFD analysis of the hot and cold fluid domains with solid-domain heat conduction through the TPMS core and shell. The final optimized design will be additively manufactured for future experimental validation.

Presenting Author: Mairah Ahmed UCF

Presenting Author Biography: I am a second-year PhD student of Mechanical Engineering at the University of Central Florida. As a graduate research assistant at the Center for Advanced Turbomachinery and Energy Research (CATER) lab, I work on developing process designs that enable decarbonisation in aviation. My current research involves exploring ammonia as an alternative fuel in aviation and investigating techniques to integrate ammonia into existing aircraft engines using simulation software for process optimization.

Authors:

Mairah Ahmed UCF
Tariq Mohd M Fadel University of Central Florida
Abhilash Prasad University of Central Florida
Maria Julia Paz Navarro University of Central Florida
Shinjan Ghosh University of Central Florida
Erik Fernandez University of Central Florida
Marcel Otto University of Central Florida
Jayanta Kapat University of Central Florida