Emission Aftertreatment Systems for Ammonia-fuelled Engines
Nygård, Mathias (2023)
Nygård, Mathias
2023
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2023050541395
https://urn.fi/URN:NBN:fi-fe2023050541395
Tiivistelmä
With the decarbonisation of the marine industry, the use of hydrogen-based fuels such as ammonia introduces a need for development of the emission aftertreatment systems, for internal combustion engines. The main components being nitrous oxides, such as NO, NO2 and N2O formed in the combustion process, as well as ammonia that passes through the engine unburned. These products, alongside the altered emission profiles, pose a significant challenge for the emission aftertreatment, with focus placed mainly on the development of the SCR system. The need for new catalyst types, and combinations of these, along with the increased understanding for the process of N2O-removal, is the driving factor for this thesis. The available catalyst types are studied and compared alongside testing and modelling, to aid in the creation of an emission aftertreatment for ammonia-fuelled engines.
A large part of the research has been aimed at the removal of N2O from the exhaust gas, as this component is the most challenging for minimising emissions, having the largest relative environmental impacts of all the emissions from ammonia combustion. The studies have been aimed at gaining understanding of the factors that impact formation and removal of N2O in the aftertreatment system. Modelling of the experimental data has been done using a semi-empirical linear regression model, as well as a mechanistic model based on the surface reactions. The models were validated using the test data from catalyst screening in lab reactors and compared to the data from a full-scale installation.
A large part of the research has been aimed at the removal of N2O from the exhaust gas, as this component is the most challenging for minimising emissions, having the largest relative environmental impacts of all the emissions from ammonia combustion. The studies have been aimed at gaining understanding of the factors that impact formation and removal of N2O in the aftertreatment system. Modelling of the experimental data has been done using a semi-empirical linear regression model, as well as a mechanistic model based on the surface reactions. The models were validated using the test data from catalyst screening in lab reactors and compared to the data from a full-scale installation.