Theoretical and experimental investigations into chemical kinetics models for supercritical CO2 oxidation

High-pressure combustion is a possible route to clean power generation. Combustion under high pressure (>7.3773 MPa), oxygen-rich conditions would produce a mixture of supercritical carbon dioxide (sCO2) and water vapour. Separation of sCO2 would be facile via condensation of water vapour, giving high purity sCO2 which could easily be transported for storage or repurposing. A further advantage of high-pressure combustion is the requirement for a smaller reaction chamber to give the same energy output as a reactor undergoing combustion at a lower pressure. This would lead to a smaller combustion plant and reduce capital costs.

This project aims to theoretically and experimentally study the chemical kinetic mechanism for the production of sCO2 at pressures exceeding 80 bar. A better understanding of the chemical kinetic model of sCO2 production would lead to more detailed and accurate model calculations to be used in the construction of high-pressure power plants by aiding in design optimization. Furthermore, an accurate chemical mechanism is required to ensure control over combustion at pressures exceeding 80 bar. The project will initially involve looking at past research to determine which mechanisms have been previously studied, the accuracy of any rate coefficients determined and if they can be used as a starting point for modelling the high-pressure combustion reaction.

Current combustion schemes have been developed for systems at atmospheric pressure, using experimental data collected at pressures much lower than the critical point for sCO2. The experimental rate coefficients determined from these experiments cannot be accurately extrapolated and used to model combustion at pressures exceeding 80 bar, leading to inaccuracies when applying current models to high-temperature combustion. The inaccuracy arises as these models may have missed reactions which become important at high pressures or just give an incorrect rate coefficient when extrapolated so far from the experimental data.

For this project, the combustion kinetics will be modelled using ANSYS Chemkin. Sensitivity analysis will be applied on ANSYS Chemkin to identify reactions which are important in the combustion mechanism at high pressures. The reactions identified will be studied experimentally using a shock tube. Part of this project also involves assisting in the construction of the shock tube which is set to begin construction in autumn 2020. The shock tube will be used to experimentally determine the rate coefficients of the reactions believed to be important at high pressures. The rate coefficients will then be input into the ANSYS Chemkin model to produce an accurate chemical kinetic model for sCO2 production upon completion of the project.

The proposed Centre will benefit the following groups

1. Students - develop their professional skills, a broad technical and societal knowledge of the sector and a wider appreciation of the role decarbonised fuel systems will play in the UK and internationally. They will develop a strong network of peers who they can draw on in their professional careers. We will continue to offer our training to other Research Council PhD students and cross-fertilise our training with that offered under other CDT programmes, and similar initiatives where that develops mutual benefit. We will further enhance this offering by encouraging industrialists to undertake some of our training as Professional Development ensuring a broadening of the training cohort beyond academe. Students will be very employable due to their knowledge, skills and broad industrial understanding.
2. Industrial partners - Companies identify research priorities that underpin their long-term business goals and can access state of the art facilities within the HEIs involved to support that research. They do not need to pre-define the scope of their work at the outset, so that the Centre can remain responsive to their developing research needs. They may develop new products, services or models and have access to a potential employee cohort, with an advanced skill base. We have already established a track record in our predecessor CDTs, with graduates now acting as research managers and project supervisors within industry
3. Academic partners - accelerating research within the Energy research community in each HEI. We will develop the next generation of researchers and research leaders with a broader perspective than traditional PhD research and create a bedrock of research expertise within each HEI, developing supervisory skills across a broad range of topics and faculties and supporting HEIs' goals of high quality publications leading to research impacts and an informed group of educators within each HEI. .
4. Government and regulators - we will liaise with national and regional regulators and policy makers. We will conduct research directly aligned with the Government's Clean Growth Strategy, Mission Innovation and with the Industrial Strategy Challenge Fund's theme Prosper from the Energy Revolution, to help meet emission, energy security and affordability targets and we will seek to inform developing energy policy through new findings and impartial scientific advice. We will help to provide the skills base and future innovators to enable growth in the decarbonised energy sector.
5. Wider society and the publics - developing technologies to reduce carbon emissions and reduce the cost of a transition to a low carbon economy. Need to ascertain the publics' views on the proposed new technologies to ensure we are aligned with their views and that there will be general acceptance of the new technologies. Public engagement will be a two-way conversation where researchers will listen to the views of different publics, acknowledging that there are many publics and not just one uniform group. We will actively engage with public from including schools, our local communities and the 'interested' public, seeking to be honest providers of unbiased technical information in a way that is correct yet accessible.