Numerical modelling of Ammonia Sprays

Ammonia (NH3) is a promising zero-carbon fuel for future transportation. Today transportation emits around 8.9 billion tonnes of CO2 annually. Whilst some sectors (e.g. cars) can be decarbonised using batteries, heavier transport (marine or freight) are less likely to use batteries due to their cost and energy density. Ammonia is a hydrogen carrier, and (by volume) contains 50% more hydrogen than liquid hydrogen (which alone is extremely energy intensive to liquefy and store). Ammonia has among the highest energy densities of any non-hydrocarbon (traditionally fossil) fuel. Ammonia is particularly attractive because it can be made using the well-established Haber-Bosch process, which today is used to make 230 million tonnes of ammonia per year. Ammonia production can be 100% renewable when powered by solar and wind. This means that ammonia production can be scalable and can be undertaken repurposing a large amount of existing infrastructure. A number of pilot projects are underway worldwide with Ammonia, including for energy storage, shipping and freight transportation. Many of these are in the UK, including at the Rutherford Appleton Laboratory, Cardiff University and the University of Nottingham. However, these projects typically adapt existing technology, which is designed for a different fuel (fossil fuels usually). There is a significant lack of fundamental data and models to enable the design of energy conversion systems specific to ammonia.
This project, then, aims to provide the model development to support this design. Taking fundamental data from an EPSRC funded project at the University of Oxford (Ammospray - EP/V04673X/1), this project will evaluate the CFD behaviour of ammonia sprays. Questions it aims to answer, for example, include: do standard spray-breakup and evaporation models (the KH-RT model is typical) suffice, or is a novel model or sub-model required? This will provide a step-change in capability for CFD analysis of ammonia combustion going forwards. This analysis and if needed new models will be freely and publicly available - catalysing future projects and enabling development of more advanced ammonia combustion systems. Similarly, the ability of the CFD to predict emissions of NOx and ammonia from ammonia combustion will be evaluated. For example the extended Zeldovich mechanisms, well recognised for NOx formation, may not be appropriate with the fuel-bound nitrogen and at the low temperatures found with ammonia combustion.
This will be done in collaboration with industrial partner Convergent Science Inc. Its CONVERGE CFD software is used by companies globally, and the model development undertaken in this project will be coded in its commercial modelling software (computational fluid dynamics (CFD)). This will be used to develop models for ammonia spray breakup, mixing, and emissions formation upon combustion. This will all happen in parallel with Ammospray experimental program and will ensure that the project's utility well beyond the project itself, with the models developed being available to be used by any of the global users of the software.
This project falls within the EPSRC Energy research area.