Improved driving-scenario-based inventories for real world tailpipe emissions from contemporary vehicles

Air pollution is a major problem globally, with ambient (outdoor) air pollution estimated by the World Health Organisation to cause 4.2 million premature deaths per year. In urban areas vehicle emissions are a or the major source of air pollution, and strategies for reducing traffic and promoting appropriate technologies are needed, but these strategies require robust data on current and future vehicle emissions.

Despite improvements in vehicle engine technology, traffic exhaust emissions have large uncertainties, due in large part to the differences between laboratory and real world performance of vehicles. In 2017, new European regulations required every new vehicle undergo the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) in the laboratory, and by 2019, all new vehicles will additionally be required to undergo Real Driving Emissions (RDE) tests as well, with Portable Emissions Measurement System (PEMS) monitors tracking emissions over 90 miles of different driving conditions.

While these tests will provide major improvements, the emissions at the end of the day will be specified by a single average number for each pollutant (for example g/km). Therefore there are likely to remain to be large uncertainties in urban emissions inventories that can only be reduced by understanding how emissions production depends for example on traffic flow, topography, and hybrid engine operation mode. Figure 1. shows an example of how nitrogen oxides (NOx) emissions vary profoundly along an urban driving route.

This PhD will develop a fleet emissions model toolkit, underpinned by experimental validation that can be used to produce improved urban emissions inventories by integrating location specific information on roads and traffic patterns with knowledge on engine mode-dependence on emissions and NOx/PM ratio for contemporary hybrid and ICE vehicles. This model toolkit will make it possible for policymakers and local authorities to have a much clearer understanding of how traffic flow regulation and fleet change incentive strategies can reduce environmental and human health impacts of urban air pollution. Additionally, this model toolkit will be able to evaluate which vehicle types are most appropriate for which journey types in an urban landscape to minimize environmental impact and human exposure to air pollution.

A real-world emissions measurement experiment conducted in partnership with industry will provide critical understanding for the student to be used in modelling. These results will be compared with the Ricardo WAVE combustion and emissions model outputs for the same vehicles. A modelling toolkit will be developed to incorporate WAVE-type calculations with local information on traffic composition and flows. Emissions will be modelled in selected small (e.g. 1km) busy urban areas for NOx and particulate matter 2.5 microns and smaller (PM2.5) for a realistic fleet composed using the average emissions rates per km for the vehicles and traffic data provided by Leicestershire County Council. This will be compared with the tailpipe emissions inventory for the area. Importantly, the research will be conducted with the aim of providing evidence policymakers and automotive manufactures can use to consider trade-offs between fuel efficiency and air pollution emissions in densely populated urban environments.

Horiba-MIRA, Nuneaton, is the proposed CASE partner, providing access to and expertise in the use of their new 8 Million GBP Advanced Emissions Test Centre which includes both WLTP and RDE emissions testing capability. Additionally the PI proposes to extend an existing partnership with Leicester City Council and Leicestershire County Council on transport, working with them to incorporate traffic data.

A unique approach for this PhD is the joint supervision from Loughborough University, which will ensure the student delivers to the NERC science based the best emission information and approaches from automotive emissions perspective.

Entry requirements
Applicants are required to hold/or expect to obtain a UK Bachelor Degree 2:1 or better in a relevant subject. The University of Leicester English language requirements apply where applicable.

How to apply
Please refer to the CENTA Studentship application information on our website for details of how to apply.

As part of the application process you will need to:
• Complete a CENTA Funding form – to be uploaded to your PhD application
• Complete and submit your PhD application online. Indicate project CENTA2-PHY6-VAND in the funding section.
• Complete an online project selection form Apply for CENTA2-PHY6-VAND