The Effects of Multiple Spark Discharges and Future Fuels during Hybrid SI-CAI Combustion

This study is aimed at understanding the effects of multiple spark discharges on spark-assisted Controlled Auto Ignition when used together with future renewable fuels. The general aim of the work is to overcome some of the control issues of CAI and potentially further widen the CAI operating map so as to allow practical use on future automotive spark ignition engines (used either alone or within an electric hybrid powertrain). The project will involve fundamental study of such combustion modes in both optical and thermal research engines using combinations of gasoline, hydrogen, ethanol and butanol fuels.

1. Social, Environmental & Economic Impact In terms of CO2 emissions, consider the best-case scenario where all automotive SI engines were replaced with CAI capable units, providing a CO2 reduction of ~15% over the European drive cycle. Thus, the total reduction in CO2 in the UK alone could be as high as ~0.4million metric tons per annum. These figures neglect any further reduction in CO2 from the use of gasoline-alcohol blended fuels, with potential additional source-to-wheel CO2 reductions of between 30-90% quoted in the literature depending on how renewable alcohol fuels can be produced and utilised. Such widespread adoption of CAI will also have a positive impact on urban air quality. At present, smoke emissions from diesels are managed via particulate filters but issues still remain with their efficiency. Furthermore, small nano-particulates can escape the filtration process and are of major health concern. From an economic stance, the impact of differences in engine materials and costs should also be considered. The cost of future CAI engines may be up to ~50% higher than current gasoline engines. That said, such engines should still remain cheaper than current diesels, which require a more robust architecture and sophisticated fuel injection and emissions after-treatment equipment. However, some caution is required when reviewing such facts as other issues must be considered as fully detailed within the attached Pathways to Impact document. 2. Industrial Impact The work is partly aimed at combining moderate downsizing with CAI operation either alone or as part of a hybrid electric powertrain, a successful outcome of which should offer significant value throughout the global automotive industry in the longer term. Specifically, both engine and fuel manufacturers stand to benefit from the planned dissemination of the results. This includes the industrial partner for the work, BP, gaining improved understanding of fundamental effects of potential next generation fuels, including their potential future bio-products. The strong alignment between this work and research now underway at BP is highlighted within their accompanying statement of support. Elsewhere, component suppliers will benefit from enhanced awareness of the future requirements of hardware currently being developed for downsized SI engines. Automotive manufacturers will also gain insight in to the potential fuel economy and emissions gains for future fleet-averaged projections. The preservation of three-way catalyst technology will also help car makers to maintain acceptable emissions after-treatment costs, unlike some competing technologies such as stratified charge SI engines or downsized turbo-diesels. 3. Academic Impact Already discussed in the academic beneficiaries section. 4. Dissemination and Exploitation The results would be disseminated throughout the international engine research community through publication of the results at high impact conferences, with at least one US-based journal paper (e.g. SAE journals) and another within the EU (e.g. Institute of Mechanical Engineers) targeted. The support of the EPSRC and industrial partner will be fully acknowledged. The papers would also be deposited in the University Research Archive and the results advertised on the centre's website. Standard agreements are also in place to protect previous and arising IPR. Otherwise, the results would be widely disseminated throughout the UK. This would include a technical presentation to an appropriate UnICEG meeting (a national body of engine researchers from both UK industry and academia which holds well attended broadly themed sessions throughout the year). Finally, in order to discuss potential future collaborations, the author would also offer technical presentations to specific UK-based industrial contacts of Brunel with strong interest in CAI combustion (including JLR, SAIC, Denso, Ricardo, Mahle, Lotus, Shell and Innospec).