Felix Leach DPhil (Oxon) MEng CEng MIMechE FHEA

Felix Leach is an Associate Professor of Engineering Science, and Fellow and Tutor in Engineering Science at Keble. Felix is a Chartered Engineer (MIMechE), a Fellow of the Higher Education Academy, and a Member of the Society of Automotive Engineers.

His research interests are in thermal propulsion systems and air quality. He runs projects on green-ammonia for propulsion (Ammospray - funded by EPSRC), air (NO2 and PM) and noise pollution in Oxford (OxAria - funded by NIHR and NERC), and hybrid propulsion systems (an EPSRC Prosperity Partnership with Jaguar Land Rover, Siemens, and the University of Bath). 

Felix’s previous projects have included a long collaboration with JLR in two centres of excellence using world-leading measurement capabilities to develop high-efficiency, low-emission engines. He has also worked on advanced measurement techniques for engine diagnostics and influences of fuels on emissions. He is working on . Felix has a significant engagement with public policy on emissions and air quality. He has run projects with Oxford City Council, Oxfordshire County Council, and the Oxford Bus Company, and is frequently consulted on the link between policy and air quality.

Felix is an associate editor of the ASME Journal of Engineering for Gas Turbines and Power, a member of the SAE Fuels and Lubricants committee.  He is the author, with Kelly Senecal, of the prize-winning book Racing Toward Zero: The Untold Story of Driving Green.

Felix won the 2014 Richard Way memorial prize, the 2018 and 2019 SAE Excellence in Oral Presentation awards, the 2021 ASME ICED Most Valuable Technical Paper Award, the 2022 Independent Press Award (Environment category), and the 2022 SAE Forest R. McFarland Award.

Proudly, he won a 2021 Department of Engineering Science Bronze Teaching Award.

My research is in thermal propulsion and air quality. Specifically, I am running projects in the following areas at the moment:

Green Ammonia for Propulsion

Ammonia (NH3) is a promising zero-carbon fuel for future transportation. Today transportation emits around 8.9 billion tonnes of CO2 annually. Whilst some sectors (e.g. cars) can be decarbonised using batteries, heavier transport (marine or freight) are less likely to use batteries due to their cost and energy density.

Ammonia is a hydrogen carrier, and (by volume) contains 50% more hydrogen than liquid hydrogen (which alone is extremely energy intensive to liquefy and store). Ammonia has among the highest energy densities of any non-hydrocarbon (traditionally fossil) fuel. Ammonia is particularly attractive because it can be made using the well-established Haber-Bosch process, which today is used to make 230 million tonnes of ammonia per year. Ammonia production can be 100% renewable when powered by solar and wind. This means that ammonia production can be scalable and can be undertaken repurposing a large amount of existing infrastructure.

A number of pilot projects are underway worldwide with Ammonia, including for energy storage, shipping and freight transportation. Many of these are in the UK, including at the Rutherford Appleton Laboratory, Cardiff University and the University of Nottingham. There is a significant lack of fundamental data to enable the design of energy conversion systems specific to ammonia.

This project, AmmoSpray, aims to fill this gap. AmmoSpray will provide, for the first time, fundamental data on ammonia sprays into air. Ammonia can be sprayed into air either as a liquid or as a gas, and both will be investigated in this project. The fundamental data obtained will include spray break-up (how liquid ammonia breaks up and evaporates upon injection) and how ammonia and air mix under realistic conditions.

These studies will be undertaken on three different pieces of test equipment:

1. An ambient conditions spray rig

2. A Cold Driven Shock Tube (CDST)

3. An optical access thermal propulsion system (TPS)

The spray rig is fast and cheap to run, and will enable the development of the experimental systems required for this project, the testing of large numbers of spray test conditions, and will be used to undertake a scoping exercise to identify project boundaries.

The CDST is a unique facility in the UK, able to replicate conditions found during combustion (150 bar pressure, 1500 K temperature) without turbulence, and with space for test equipment. This will enable for the first time imaging and break-up studies of ammonia sprays at conditions that will be seen in-use - key fundamental data.

The optical TPS tests are the logical next step, adding turbulence, and replicating as closely as possible 'real' conditions, whilst still allowing access for imaging and test equipment. The key tests here will be on mixing, using a laser-based technique (PLIF) to obtain ammonia:air ratio measurements throughout the combustion volume. This will link the sprays information developed earlier to their combustion characteristics. The tests on the optical access TPS will also enable studies of how these different spray and mixing methodologies influence emissions formation for ammonia combustion, with NH3 and NOx the key emissions which will be measured.

This step-by-step nature is perfectly suited for improving existing models. The data obtained will be coded into commercial modelling software (computational fluid dynamics (CFD)) provided by project partner, Convergent Science. Its CONVERGE CFD software is used by companies globally. The data obtained will be used to develop models for ammonia spray break-up, mixing, and emissions formation upon combustion. This will all happen in parallel with the experimental program and will ensure that the project's utility well beyond the project itself, with the models developed being available to be used by any of the global users of the software.

Air quality

Emergency public health measures were implemented across the UK in early 2020 to suppress COVID-19 transmission; with major implications for ambient air quality (AQ). Well publicised satellite data have indicated associated reductions in air pollutant (AP) concentrations with potential benefits for human health; however ground-based measurements suggest more complex trends in UK cities. These events present a unique natural experimental opportunity to better understand environmental consequences arising from these measures and to apply this learning to future AQ intervention scenarios. Our research focus is Oxford (population ~155,000). Oxford has significant AQ and health inequity challenges, with the equivalent of 1 in 20 early deaths attributed to AP exposure. The City and County Councils plan to introduce a Zero Emissions Zone and enhanced Low Emission Zone from 2022 and to achieve carbon neutral status by 2030. Oxford is also a focal point for existing research activity, including NIHR, Defra, Highways England and Research England funded studies supporting a broad range of environmental and transport monitoring capabilities and existing research infrastructure, with a network of 16 air pollution (NO2, PM, Ozone, and NO) sensors deployed in the city. The OxAria project enabled a robust evaluation of the positive and negative impacts of introduction, maintenance and removal of COVID-19 measures in Oxford City. The data assimilated generated a series of AQ control scenarios and predicted health benefits, thereby informing and redefining council-led AQ policy and climate strategy.

Hybrid propulsion systems

The scale of the investment (in power generation, transmission and charging infrastructure) that is required to support the widespread adoption of Electric Vehicles (EVs) is massive. This, combined with natural delays associated with fleet turnover and consumer acceptance and adoption of new technology, suggests that the transition to a predominantly grid-supplied EV fleet will be gradual and often infrastructure-limited.

An EPSRC Prosperity Partnership between Oxford, Siemens, Jaguar Land Rover, and Bath proposes a new and faster route to full fleet electrification. We propose to develop a Thermal Propulsion System (TPS) that, combined with a matched hybrid energy recovery system, will be capable of powering an EV from an energy dense liquid fuel at the same or lower economic and environmental cost than would be incurred by importing electricity to the vehicle from the grid.

By utilising a globally established refuelling network of proven capacity, the TPS technology that will be delivered by this partnership will enable the widespread adoption of zero-emissions capable, electrically driven, vehicles ahead of the required infrastructure developments of the grid-dependent Battery Electric Vehicle (BEV) and the hydrogen Fuel Cell Electric Vehicle (FCEV). This will lighten the burden on the UK's electricity generating capacity and distribution network as BEV and FCEV usage increases, allowing valuable time for the required development of grid and charging infrastructures while simultaneously providing an option for low carbon transport at times of low renewable input to the grid.

This work is of substantial national importance to the UK's manufacturing sector. The research will protect the role of the TPS, and the UK's well-established engine manufacturing expertise, within the rapidly growing low-emission vehicle sector of the automotive market. The UK government predict that the global market for these low-emissions vehicles could be worth £1.0-2.0 trillion per year by 2030, and £3.6-7.6 trillion per year by 2050. The UK's automotive supply chain as a whole would benefit from the world leading technology that this Partnership seeks to provide.

This Partnership combines the industry knowledge, design and manufacturing resources of Jaguar Land Rover (JLR), with the academic expertise of two of the UK's leading TPS research groups. The University of Oxford are world-leaders in the development of optical diagnostics and the study of in-cylinder phenomena: sprays, combustion and emissions. The University of Bath are similarly expert in the study of air handling, waste heat recovery and the systems-level analysis and modelling of vehicle powertrain.

The research is divided into interrelated "Grand Challenges". Jaguar Land Rover will lead the TPS concept design and evaluation. The University of Oxford will perform fundamental experimental studies on mixing, ignition, combustion and emissions formation under extreme lean-burn and highly dilute conditions relevant to hybrid-focused TPS operation. The data from these experiments will be used at Oxford to develop and validate new predictive models that, in turn, will feed back into concept design process at JLR and systems models at the University of Bath. Oxford will also develop new and improved measurement tools and methods for the experiments. The University of Bath will investigate low-grade and high-grade heat recovery, air-handling and boosting systems--demonstrating and evaluating concepts on a prototype multi-cylinder TPS and feeding back in to JLR's concept design process. Bath will also perform extensive systems and vehicle modelling of the TPS system (using models validated against Oxford's data) in a hybrid powertrain to optimise system-level energy balance and demonstrate the target systems-level energy recovery in a virtual environment.

• Ammospray Fundamental ammonia spray data and model development for zero-carbon propulsion
• Centre of Excellence for Hybrid Thermal Propulsion Systems Working alongside Jaguar Land Rover, Siemens and Bath in reducing emissions and increasing efficiency in hybrid engines.
• OxAria Measurement of air and noise pollution across Oxford using a network of low-cost sensors
• Indoor air quality Careful measurements of air pollution (particularly NO2 and PM) in the indoor environment
• Machine learning tools for emissions prediction Using different, but importantly physically interpretable machine learning techniques applied to all my other projects
• Public Policy Engagement with the public and media influencing the discourse on future mobility

I am always interested to hear from people interested in doing a DPhil. Projects would be in the general area of thermal propulsion, ammonia, and air quality / noise pollution, but please get in touch to discuss specific projects and ideas.