Keywords

Hydrogen, Autoignition, Turbomachinery, Hydrogen enriched natural gas

Abstract

The successful transition to global clean energy is contingent upon meeting the increasing worldwide energy demand for power while simultaneously curbing greenhouse gas emissions. This study delves into the complexities of transitioning to cleaner energy sources and the challenges posed by utilizing hydrogen and hydrogen/natural gas mixtures as a potential fuel source alternative to traditional carbon-based combustion cycles. By addressing the technical intricacies and conducting thorough testing, researchers aim to enhance our understanding of auto-ignition behavior in different fuel-air mixtures under varying conditions, ultimately contributing to the development of safer and more efficient energy solutions in the pursuit of clean and sustainable power generation.

This study outlines the test methodology employed to assess conditions leading to auto-ignition for various fuel-air mixtures operating at different pressures (1 - 30 atm) and temperatures. The testing encompassed 100% H2 and multiple H2/NG blends at stoichiometric conditions. Similar testing was conducted for 100% NG to validate the test procedures and data collection methods referenced in previous literature. Under atmospheric conditions, 0-1 ATM, H2 exhibits a broader flammability range of EQs where ignition is more likely to occur compared to methane. H2's flammability ranges from 4% to 75% molar (volume) fuel concentration, corresponding to an EQ range of 0.137 - 2.57, while methane's flammability limit spans from 5% to 15% molar (volume) or an EQ between 0.53 – 1.58. Previous studies have explored the effect of longer hydrocarbons present in natural gas mixtures, with ethane (C2H6) and propane (C3H8) shown to decrease the ignition temperature (AIT) of natural gas, particularly at elevated pressures. These longer hydrocarbons are inclined to promote ignition in richer conditions, whereas methane tends to ignite more readily in slightly lean conditions. Besides pressure, fuel, and EQ, numerous variables such as chamber volume size, chamber materials, presence of diluents, and other factors can influence the AIT. The results revealed that, at atmospheric pressures, an increase in H2 concentration led to a reduced AIT. However, at 30 atm, a higher presence of H2 increased the AIT. At pressures exceeding 10 atm, an increased equivalence ratio resulted in a decreased AIT for all mixtures, with NG, exhibiting the greatest sensitivity to equivalence ratio variations.

Completion Date

2024

Semester

Summer

Committee Chair

Vasu, Subith

Degree

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

College

College of Engineering and Computer Science

Department

Engineering

Degree Program

Aerospace Engineering

Format

application/pdf

Identifier

DP0028615

URL

https://purls.library.ucf.edu/go/DP0028615

Language

English

Rights

In copyright

Release Date

August 2025

Length of Campus-only Access

1 year

Access Status

Masters Thesis (Campus-only Access)

Campus Location

Orlando (Main) Campus

Accessibility Status

Meets minimum standards for ETDs/HUTs

Download

Restricted to the UCF community until August 2025; it will then be open access.

Share

COinS