Fundamental combustion chemistry of hydrogen and ammonia fuel blends

Given concerns on the combustion of fossil fuels and the associated greenhouse gas emissions, their
elimination is actively being sought.

In some cases, however, there is a continuing need for combustion in industries where onsite combustion is essential, such as steel manufacture. In these cases, hydrogen has positioned itself as the ideal fuel to phase out carbon emissions given its zero emissions and high heating value.

However, despite these advantages, hydrogen has significant barriers in the form of safety, storage, and ease of transportation. Therefore, chemical hydrogen carriers have been identified as an alternative to the direct use of hydrogen. Transforming hydrogen into ammonia at the point of synthesis would reduce the pressure and temperature requirement whilst improving safety. The current drawback to this is the energy cost of the dehydrogenation step and that the conversion of ammonia is only partial, leading to some ammonia and a certain amount of nitrogen remaining in the fuel.

This project aims to improve the understanding of the burning of hydrogen/ammonia/nitrogen blends by the use of a high-pressure shock tube facility to measure the ignition delay time as a function of temperature and pressure of various fuel mixtures. These will be complemented by experiments using an opposed flow diffusion flame in which temperature and species profiles (OH and potentially NH and NH2) through the diffusion flame can be determined using a planar laser-induced fluorescence technique.

These experiments will provide data to enable the validation and enhancement of chemical kinetic models of ammonia/hydrogen blend combustion, to be implemented in ANSYS Chemkin-Pro. The outcome will be better chemical kinetic models to give an enhanced understanding of the actual combustion behaviour of hydrogen/ammonia/nitrogen fuel mixes.

For further information contact Professor Derek B Ingham
(d.ingham@sheffield.ac.uk).