High Hydrogen Content (HHC) Fuel Burning at High Pressure

Lead Research Organisation: University of Southampton
Department Name: Faculty of Engineering & the Environment

Abstract

To have a realistic chance of reducing the carbon footprint before 2020, intensive actions are required before the date by which a new international climate agreement is due to come into force. Combustion is at the heart of this challenge: fossil fuel combustion accounts for around two-thirds of greenhouse-gas emissions, as more than 80% of global energy consumption is based on fossil fuels. Worldwide, fossil fuels add more than twenty five billion tons of carbon dioxide to the atmosphere every year, along with vast quantities of other pollutants. This places enormous pressure to improve the combustion efficiency with low emissions in transportation and power generation devices while simultaneously developing more diverse fuel streams, including low carbon fuels. In moving towards cleaner combustion technologies, high hydrogen content (HHC) alternative fuel blends, especially those containing significant quantities of hydrogen are undoubtedly significant, because they are environmentally friendly and can be used as an alternative feedstock for energy resources in the clean energy generation. Unfortunately, the technical applicability of HHC fuels exhibit major challenges both fundamentally and practically due to three major reasons. Firstly, the combustion processes of HHC fuels is associated with high level of diffusivity and flame temperature which affect the flame speed, heat release rate, pollutant formations, and more importantly flame stability mechanisms. Secondly, combustion engines in power generation and transportation are generally operating at high pressure (e.g. 10-100 bar). Current chemical models for combustion consist of kinetic data of thousands of reactions. These models are validated through detailed comparisons with wide ranges of experimental observations of flame properties. However, much of the validation has been done for low pressure (e.g. 1bar), whereas combustion devices are mostly functioning at much higher pressure (e.g. 20-100 bar). Thirdly, there is less/no information available regarding the emission formations of HHC fuel burning at high pressure. As a result of the wide range of compositions found in high hydrogen fuels, strategies well suited for low emissions performance on conventional fuels such as natural gas may not necessarily work best for hydrogen containing fuels. Because of this, many existing combustors used for hydrocarbon content fuels will require new and refined techniques to achieve safe and controllable HHC fuel burning at high pressure, which is crucial for future clean combustion technology developments. Therefore, there is a clear need to investigate the combustion science of alternative clean fuels at high pressure. In order to meet the challenges posed by the HHC fuel burning at high pressure, a detailed parametric study by systematically varying the percentage of the fuel composition at different high pressure levels is highly desired. The aim of this proposal is to develop new computational experiments to fundamentally understand the burning issues of HHC fuels at high pressure conditions. The project will demonstrate how the new predictive engineering models can be used to utilise HHC fuels, highlighting the effects of high pressure on clean fuel burning, overall performance, emission distributions and finally provide an optimised industrial guidelines to design combustor performance for hydrogen-rich clean fuel burning at high pressure. The industrial guidelines will particularly address the applicability of hydrogen-rich clean fuel burning for gas turbine combustion and operability. This project will investigate the effects of high pressure on HHC fuel burning, and to generate a comprehensive computational database in order to establish industrial guidelines for burning issues of hydrogen-rich fuel at high pressures.

Planned Impact

Outside the academic community, the impact of the research will principally benefit the energy industry. The key application of the majority of research in thermal energy is clean combustion. Furthermore, improving the understanding of the combustion of high hydrogen content (HHC) fuels at high pressure will ultimately benefit the public at large by reducing the pollutant emissions and improving combustor designs for better fuel economy and safe operation. The proposed research will help to gain unique and important physical insights into the understanding of the combustion characteristics of high hydrogen content fuel burning at high pressure. High-fidelity numerical simulations have made it possible for a systematic investigation of combustion science of evolving clean fuels at high pressures. The proposed project is part of a long-term effort to keep the UK in the forefront of clean energy research and climate change mitigation. The project will deliver a fundamental science of the utilisation of high hydrogen content clean fuels, which can be derived from both renewables such as biofuels and non-renewables such shale gas. The project will highlight the effects of variable clean fuel compositions on chemical propulsion, overall performance and emission distributions at high pressures. The research outcome will be internationally leading in the areas of hydrogen as an energy career, clean combustion technology and computational combustion. In moving towards cleaner combustion technologies, high hydrogen content (HHC) fuel is undoubtedly significant because it is environmentally friendly and can be used as an alternative feedstock for energy resources in the clean energy generation. In addition, combustion engines in power generation and transportation are generally operating at high pressure (e.g. 10-100 bar). For example, combustion in spark ignition engines takes place varying pressure and combustion in stationary gas turbines takes place at elevated pressure. Considering these important factors, this project is planned to develop an in-depth understanding of high hydrogen fuel burning at high pressure with particular attention to the scientific findings of burning issues of clean fuels and emission formations at high pressure. It is anticipated that the outcome from this project will represent a significant advancement in clean combustion low emission technology. The research will have industrial impacts on combustion applications of hydrogen-enriched clean fuels. This project represents a step change in the field of computational combustion and an effort to keep the UK in the forefront of computational combustion, using state-of-the-art numerical simulation and modelling techniques. The main scientific challenge of the project is to gain a deeper understanding of the combustion science of clean fuel burning at high pressure. With the application directed towards clean fuel burning, this project can eventually benefit renewable and non-renewable fuel based clean energy industry in the world. This in turn will lead to cleaner combustion and better global environment.
 
Description The research from this project was focused on developing and applying fundamental theoretical and computational techniques to better understand and improve new cleaner energy technologies and emission concerns with particular emphasis on combustion characteristics of High Hydrogen Content synthetic fuels (syngas) at high pressure conditions similar to more practical oriented combustion engine conditions. The project developed new full-fidelity and high-fidelity computational experiments in order to fundamentally understand the burning issues of high hydrogen content syngas fuels at elevated pressures similar to engine conditions.

Three-dimensional direct numerical simulations (DNS) using detailed chemistry have been performed to investigate the burning characterises of high hydrogen content syngas fuels under low and high initial turbulence levels at high pressure conditions. We examined how pressure increment from atmospheric to high pressures affects high hydrogen content syngas flame characteristics including small and large scale flame wrinkling, the spatial variation of the local heat release rate and radical species distributions. We also examined the role of preferential diffusion (i.e. non-unity Lewis number effects) on high hydrogen content syngas flame structure and propagation under low and high initial turbulence levels at elevated pressures. We attempted to identify the flame markers for high hydrogen content syngas turbulent premixed flames burning at elevated pressures. As new combustion engine concepts progressively move towards learn burn combustion technology to take advantage of the fact that combustion processes operating under fuel lean conditions can have low emissions and high efficiency, majority of the direct numerical simulation test cases have been performed for lean premixed combustion mode at elevated pressures.

The project findings indicate that the flame front wrinkling of high hydrogen content lean premixed syngas flames develop under turbulent conditions at elevated pressures is affected by both turbulence and natural flame instabilities, depending on the initial turbulence level imposed at the beginning. The findings of the work indicate that the preferential diffusion effects play a significant role on forming small scale thermo-diffusive instability cells for high hydrogen content lean premixed syngas flames develop under low initial turbulence level at elevated pressures. In contrast, the findings also indicate that the thermo-diffusive instability is overwhelmed by turbulent mixing for high hydrogen content lean premixed syngas flames develop under high initial turbulence level at elevated pressures. The findings also show noticeable increases in the local heat release rate with increasing pressure. The findings also indicate that the high hydrogen content lean premixed syngas flame is more unstable than the stoichiometric and rich premixed syngas flames at elevated pressures. The project also identified several heat release rate markers for high hydrogen content turbulent premixed flames at elevated pressures.

The novel scientific findings of the project are published in 7 publications including 3 journal articles in International Journal of Hydrogen Energy. Overall, the project provided fundamental scientific breakthroughs for high hydrogen content alternative clean fuel burning for fuel-lean, stoichiometric and fuel-rich combustion modes at elevated pressures. The project findings can be effectively used as industrial guidelines to utilise high hydrogen content alternative fuels for next generation high efficiency and low emission stationery and motive combustion engines.
Exploitation Route The novel scientific findings of the project are published in 7 publications including 3 journal articles in International Journal of Hydrogen Energy. Overall, the project provided fundamental scientific breakthroughs for high hydrogen content alternative clean fuel burning for fuel-lean, stoichiometric and fuel-rich combustion modes at elevated pressures. The project findings can be effectively used as industrial guidelines to utilise high hydrogen content alternative fuels for next generation high efficiency and low emission stationery and motive combustion engines.

The findings of the directly integrate clean fuels into power generation and transportation, thereby mitigating the greenhouse effect. The findings of the project bring many direct and indirect social impacts, particularly with respect to low carbon fuel options. It provides much-needed technical guidance for fuel flexibility, sustainability and emission control which could help achieve the UK's long term emission targets. Economically, the finding of this study can contribute to the reduction of electricity output penalty (EOP) for greenhouse gases.
Sectors Energy,Environment

URL http://www.southampton.ac.uk/engineering/about/staff/jkk1d12.page
 
Description The project involved interdisciplinary research with close interaction between mathematics, engineering sciences, life sciences and technology. The project provided much-needed technical guidance for environmental performance, sustainability and durability improvements in hydrogen based fuel-flexible propulsion systems hence helped in achieving the UK and global short term and long term emission targets. Economically, the finding of this study contributed to the reduction of power output penalty (EOP) for greenhouse gases. New strategies and findings emanating from this multidisciplinary research ultimately benefited shaping the clean energy and green combustion engineering systems.
First Year Of Impact 2016
Sector Energy,Environment
Impact Types Economic

 
Description Centre for Doctoral Training in Next Generation Computational Modelling
Amount £60,000 (GBP)
Organisation University of Southampton 
Sector Academic/University
Country United Kingdom
Start 10/2016 
End 09/2019
 
Description EPSRC Industrial Strategy Studentship
Amount £90,000 (GBP)
Organisation University of Southampton 
Sector Academic/University
Country United Kingdom
Start 10/2017 
End 09/2021
 
Title Direct Numerical Simulation 
Description Direct Numerical Simulation is a high-resolution numerical tool in which all relevant continuum scales are resolved which can discover complex scientific and technological issues. 
Type Of Material Technology assay or reagent 
Year Produced 2015 
Provided To Others? Yes  
Impact Investigate fundamental turbulence-flame interactions 
 
Description Direct Numerical Simulation of High Hydrogen Fuel Burning at High Pressure 
Organisation Eindhoven University of Technology
Department Department of Biomedical Engineering
Country Netherlands 
Sector Academic/University 
PI Contribution Some original ideas for high-resolution numerical simulations were proposed.
Collaborator Contribution Some original ideas or hypothesis were proposed by the collaborators, for example: tabulated chemistry for high-resolution simulations,.
Impact Ranga Dinesh, K.K.J., van Oijen, J., Luo, K. and Jiang, X. (2015) Nitric oxide pollutant formation in high hydrogen content (HHC)syngas flames. International Journal of Hydrogen Energy, 40, (39), 13621-13634. (doi:10.1016/j.ijhydene.2015.08.068).
Start Year 2011
 
Description Direct Numerical Simulation of Turbulent Combustion 
Organisation The Otto-von-Guericke University Magdeburg
Country Germany 
Sector Academic/University 
PI Contribution Simulation of high hydrogen content flames at high pressure
Collaborator Contribution Development of full-fidelity direct numerical simulation code
Impact Ranga Dinesh, K.K.J, Shalaby, H, Luo, K.H, Thevenin, D. "Influence of preferential diffusion in turbulent lean premixed hydrogen-rich syngas spherical flames at elevated pressures" 7th European Combustion Meeting, Budapest, Hungary, 2015 Ranga Dinesh, K.K.J, Shalaby, H, Luo, K.H, Thevenin, D. "Flame structure analysis for turbulent lean premixed spherical flames at elevated pressures" 7th European Combustion Meeting, Budapest, Hungary, 2015 Ranga Dinesh, K.K.J, Shalaby, H, Luo, K.H, Thevenin, D. "DNS of turbulent lean premixed syngas flames at elevated pressures" ERCOFTAC Workshop Direct and Large-Eddy Simulation 10 (DLES10), Limassol, Cyprus, 2015 Ranga Dinesh, K.K.J, Shalaby, H, Luo, K.H, Thevenin, D. "Numerical investigation of turbulent lean premixed H2/CO combustion at elevated pressures" 25th International Colloquium on the Dynamics of Explosions and Reactive Systems (ICDERS2015), Leeds, UK, 2015
Start Year 2014
 
Description High Resolution Numerical Simulation 
Organisation University College London
Department Bartlett Development Planning Unit
Country United Kingdom 
Sector Academic/University 
PI Contribution Computational code optimisation to perform high resolution numerical simulation
Collaborator Contribution Allocate computational resources
Impact Ranga Dinesh, K.K.J, Shalaby, H, Luo, K.H, Thevenin, D. "Influence of preferential diffusion in turbulent lean premixed hydrogen-rich syngas spherical flames at elevated pressures" 7th European Combustion Meeting, Budapest, Hungary, 2015 Ranga Dinesh, K.K.J, Shalaby, H, Luo, K.H, Thevenin, D. "Flame structure analysis for turbulent lean premixed spherical flames at elevated pressures" 7th European Combustion Meeting, Budapest, Hungary, 2015 Ranga Dinesh, K.K.J, Shalaby, H, Luo, K.H, Thevenin, D. "DNS of turbulent lean premixed syngas flames at elevated pressures" ERCOFTAC Workshop Direct and Large-Eddy Simulation 10 (DLES10), Limassol, Cyprus, 2015 Ranga Dinesh, K.K.J, Shalaby, H, Luo, K.H, Thevenin, D. "Numerical investigation of turbulent lean premixed H2/CO combustion at elevated pressures" 25th International Colloquium on the Dynamics of Explosions and Reactive Systems (ICDERS2015), Leeds, UK, 2015 Ranga Dinesh, K.K.J., van Oijen, J., Luo, K. and Jiang, X. (2015) Nitric oxide pollutant formation in high hydrogen content (HHC)syngas flames. International Journal of Hydrogen Energy, 40, (39), 13621-13634. (doi:10.1016/j.ijhydene.2015.08.068).
Start Year 2013