In-situ Diagnostics and Modeling of Ammonia spray Physics and Combustion Behavior at Elevated Pressure

With the global trend of decarbonization and growing interests in sustainable transportation and propulsion, it becomes increasingly important to understand the combustion performance and emission characteristics of carbon-free fuels under practical operation conditions. Ammonia has attracted extensive research interests as a carbon-free fuel and an effective hydrogen carrier, due to its relatively high volumetric energy density, low cost, convenience to store and deliver, and mature production infrastructure from renewable resources.

A major obstacle yet to be resolved is the emission of nitric oxide and unburnt ammonia during combustion, both of which are strongly coupled with the spray and mixing process. This proposal focuses on the understanding the characteristics of high-pressure liquid ammonia spray and combustion, with pressures up to 80 bar, to inform future carbon-free transportation and propulsion systems.

The proposed efforts will also broaden participation in research and integrate research with teaching to enhance student learning. The proposed work will not only impact on the fundamental spray dynamics and combustion kinetics, but also be transformative for the development of carbon-free transportation and propulsion systems.

The goal of this research is to combine comprehensive in-situ laser diagnostics and numerical simulation to provide in-depth understanding of ammonia sprays under non-vaporizing, vaporizing, and reacting conditions. This fills a substantial knowledge gap and requires a combination of expertise in advanced laser diagnostics and high-fidelity numerical simulations.

Advanced laser diagnostics will include 2D Raman, PLIF and rainbow reflectometry to acquire flow, key reaction intermediates and droplet size distribution. These experimental measurements will provide unprecedented details about the performance and emission characteristics of high-pressure ammonia combustion as a carbon-free fuel. Information of the flow, temperature, droplet and chemical intermediate distribution will also provide valuable targets to validate simulations using both open source CFD code and commercial software to enhance modeling and prediction capability for future clean combustion systems.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.