Chemical Energy Converters

Analytical Approach to Characterize the Effect of Engine Control Parameters and Fuel Properties on ACI Operation in a GDI Engine

Cohort: Cohort 3
Date: 01 01 2020

Advanced compression ignition (ACI) operation in gasoline direct injection (GDI) engines is a promising concept to reduce fuel consumption and emissions at part load conditions. However, combustion phasing control and the limited operating range in ACI mode are a perennial challenge. In this study the combined impact of fuel properties and engine control strategies in ACI operation are investigated. A DOE was implemented to determine the sensitivity of engine control parameters on the engine load, combustion noise and stability under low load ACI operation for three RON 98 gasoline fuels, each exhibiting disparate chemical composition. Furthermore, the thermodynamic state of the compression histories was studied with the aid of the pressure-temperature framework. Due to the compression ratio constraints imposed by knock limited SI operation, considerable intake temperature heating was required and ACI operation resulted in the intermediate to high temperature autoignition regime. The olefin containing fuel was found to be most sensitive to intake air heating, thereby enhancing its potential suitability for ACI operation, while still enabling high load SI operation. This work was conducted during Johannes’s employment Argonne National Laboratory.

Digital Systems, Optimisation and Integration

Blade Surface Pressure Measurements on a Low Pressure Rise Axial Flow Fan

Proceedings of the ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. Volume 1: Aircraft Engine; Fans and Blowers
Cohort: Cohort 3
Date: 25 09 2020

Fan performance characteristic tests of axial flow fans provide information on the global flow field, based on stable inlet flow field distribution. More information is often required on the local flow distribution existing in the vicinity of the fan blades. In this study, a numerical and experimental investigation of a large diameter axial flow fan is conducted to investigate its local pressure distribution and performance. Two specially constructed M-Fan blades with thirty-five pressure taps at five radial locations are manufactured to conduct blade surface pressure measurements on the blades. The experimental M-Fan results are compared against results from a periodic numerical CFD model of a fan blade modelled in an ISO 5801, Type A test facility configuration. The experimental tests and numerical model correlate well with each other and details of the fan blade performance are provided in the paper. This work was conducted during Johannes’s Master of Mechanical Engineering (MEng) at the University of Stellenbosch.

Digital Systems, Optimisation and Integration

A Case for Technology - Forcing Transformative Changes in the Formula 1 Power Unit

SAE International
Cohort: Cohort 2
Date: 06 04 2021

A key chapter from Abdu's Master's thesis at Oxford Brookes University exploring Supervised Neural Network based Machine Learning Algorithms to Predict and Reduce Emissions in Internal Combustion Engines for Racing Applications was accepted for publication by SAE International 

The paper is titled "A Case for Technology - Forcing Transformative Changes in the Formula 1 Power Unit". Following a systematic methodology, it analytically examines area-specific emissions in F1 race events at different track stadia and proposes new targets for F1 power units in conjunction with current World Health Organization (WHO) and European Commission published exposure ug/m³ standards.

Propulsion Electrification

Is Elevated Operational Temperature a Barrier to Solid-State Battery Adoption?

Climate Exp0
Student: Ryan Hughes
Cohort: Cohort 2
Date: 17 05 2021

Ryan presented the work from his MSc dissertation on solid-state battery at the Climate Exp0 conference in the Mitigation Solutions theme. With his supervisor Dr Christopher Vagg, he found that by utilising waste heat from the electrical power train, there is enough energy to heat thermally isolated solid-state battery modules in time for them to provide tractive power for a passenger vehicle. This is important as currently available solid-state batteries require an operational temperature of 60°C.

Chemical Energy Converters

Turbocompounding the Opposed-Piston 2-Stroke Engine

SAE 2021 World Congress
Student: Alex Young
Cohort: Cohort 1
Date: 22 09 2021

For Alex's MRes summer project, he studied the effects of “Turbocompounding the Opposed-Piston 2-Stroke (OP2S) Engine” with a focus on quantifying the expected Brake Specific Fuel Consumption (BSFC) improvement. In order to achieve this, Alex needed to first create a model of an OP2S engine within GT Power, an engine simulation software package. After the MRes year was finished, Alex was able to turn the summer research project report into a conference paper which was published as part of the SAE WCX World Congress Experience Digital Summit in 2021.

Chemical Energy Converters

The Effect of Crankshaft Phasing and Port Timing Asymmetry on Opposed-Piston Engine Thermal Efficiency

Student: Alex Young
Cohort: Cohort 1
Date: 15 10 2021

Opposed-piston two-stroke engines reveal degrees of freedom that make them excellent candidates for next generation, highly efficient internal combustion engines for hybrid electric vehicles and power systems. The effect of crankshaft phasing and intake and exhaust port height-to-stroke ratios on a range of scavenging performance parameters and other effects are explored in depth in his latest article in Energies: “The Effect of Crankshaft Phasing and Port Timing Asymmetry on Opposed-Piston Engine Thermal Efficiency”, where it has been shown that lean operation favours port timing asymmetry, whereas, under stoichiometric conditions, best efficiencies are found during symmetrical port timing. 

Propulsion Electrification

Assessing the Feasibility of a Cold Start Procedure for Solid State Batteries in Automotive Applications

Student: Ryan Hughes
Cohort: Cohort 2
Date: 05 02 2022

Originating from his Master's thesis, Ryan and his supervisor Dr Chris Vagg have published their findings in a new journal article seeking to address the feasibility of a cold start procedure for solid state batteries in automotive applications. The proposed solution involves dividing the battery into sub-packs and heating them sequentially to the required 60°C, primarily using waste heat from the electric powertrain. This could allow high energy density solid state cells to be used despite their temperature constraints.

Propulsion Electrification

Effect of Internal AC Heating on the Temperature Homogeneity of Different Size Battery Cells

Cohort: Cohort 2
Date: 12 02 2022

Howard's MRes Summer Project investigated the effect that AC internal heating had on the spatial temperature homogeneity of Lithium-ion cells. With his supervisor Dr Christopher Vagg, he found that the cylindrical MoliCel and DTP Pouch cells both demonstrated significant temperature gradients when heated from sub-zero temperatures. These gradients increased in magnitude with the size of the cell and for the pouch cells were affected further by the current gradients caused by tabs located at the same end of the battery.

Chemical Energy Converters

Investigations into EGR dilution tolerance in a pre-chamber ignited GDI engine

Cohort: Cohort 3
Date: 01 03 2022

EGR is a useful means to improve fuel economy in spark-ignited gasoline engines, while also reducing NOx emissions due to the lower peak cylinder temperatures. However, the ability of conventional spark ignition systems to reliably ignite dilute mixtures limits the dilution tolerance due to the onset of combustion instability.  In this study, an active pre-chamber system was simulated and experimentally tested with various EGR rates to provide insight into its operation and performance metrics. This included an assessment of the thermodynamic states and composition over different pre-chamber operating conditions. The active pre-chamber extended the EGR dilution limit from 20% for conventional SI to above 30%, with a higher pre-chamber flow rate (more scavenging) resulting in increased combustion stability. A trade-off between the jet momentum and spark timing was observed when analysing the simulations and the pre-chamber jet momentum was found to decrease with increasing EGR rate. This work was conducted during Johannes’s employment Argonne National Laboratory.

Chemical Energy Converters

Investigation of Naphtha-Type Biofuel from a Novel Refinery Proces

WCX SAE World Congress Experience
Cohort: Cohort 1
Date: 29 03 2022

In order to reduce the carbon footprint of the Internal Combustion Engine (ICE), biofuels have been in use for a number of years. One of the problems with first-generation (1G) biofuels however is their competition with food production. In search of second-generation (2G) biofuels, that are not in competition with food agriculture, a novel biorefinery process has been developed to produce biofuel from woody biomass sources. This novel technique, part of the Belgian federal government funded Ad-Libio project, uses a catalytic process that operates at low temperature and is able to convert 2G feedstock into a stable light naphtha. The bulk of the yield consists out of hydrocarbons containing five to six carbon atoms, along with a fraction of oxygenates and aromatics. The oxygen content and the aromaticity of the hydrocarbons can be varied, both of which have a significant influence on the fuel’s combustion and emission characteristics when used in Internal Combustion Engines. When used as a blend component, this novel 2G biofuel could help increase the sustainability of vehicle fuels. But, while exhaustive experimental and, although lesser in number, numerical investigations on combustion behavior have been performed for 1G biofuels, less information is available for 2G biofuels and especially this novel naphtha-like fuel. An extensive fuel compound property database and a fuel blend property calculator is readily available in literature, but their validity has not been tested for the novel 2G biofuel components. This article provides a first screening of the usability of these light naphtha components as blend components for gasoline and diesel drop-in fuels, by means of a freely available fuel component database and fuel blend calculator, concluding with an initial assessment of achievable blends and pointing out where further work is needed.

Sustainability and Low Carbon Transition

Mobility As a Service: Why and How?

City Changers
Cohort: Cohort 2
Date: 04 04 2022

Originating from her PhD research on Mobility as a Service (MaaS), Rita wrote a short article for the City Changers website on balancing the benefits and challenges of implementing MaaS in an urban context, providing a few practical steps towards a MaaS implementation.

Digital Systems, Optimisation and Integration

Freevalve: Control and Optimization of Fully Variable Valvetrain-enabled Combustion Strategies for High Performance Hybrid Vehicles

SAE Technical Papers
Cohort: Cohort 2
Date: 13 08 2022

With ever stricter legislative requirements for CO2 and other exhaust emissions, significant effort by Original Equipment Manufacturers (OEMs) have launched a number of different technological strategies to meet these challenges such as Battery Electric Vehicles (BEVs). However, a multiple technology approach is needed to deliver a broad portfolio of products since battery costs and supply constraints are considerable concerns hindering mass uptake of BEVs. Therefore, further investment in IC engine technologies to meet these targets are being considered, such as lean burn gasoline technologies and other high efficiency concepts such as dedicated hybrid engines. Hence, it becomes of sound reason to further embrace diversity and develop complementary technologies to assist in rapid conclusions in the transition to the next generation hybrid powertrains. One such approach is to provide increased valvetrain flexibility to afford new degrees of freedom in engine operating strategies. Freevalve is an electronically controlled, pneumatic spring-based, valve actuation system enabling independent control of ICE valves conceptualized by Koenigsegg’s Freevalve AB. Developed primarily in line with increasingly strict emissions legislations, preliminary findings have demonstrated that the cam-less engine technology withholds significant potential, offering up to 10% decreased fuel consumption and 60% less cold start emissions on an average drive cycle. This paper aims to demonstrate the most recent valve operating strategies enabled by the cam-less engine technology using a simplified 3-cylinder hybrid 1D engine model in GT-Suite.

Propulsion Electrification

Carbon Fibre Lattice Strain Mapping Via Microfocus Synchrotron X-Ray Diffraction of a Reinforced Composite

Journal: Carbon
Student: Rob Gray
Cohort: Cohort 1
Date: 11 08 2022

Thomas and Rob aided a Synchrotron X-Ray diffraction (SXRD) strain analysis experiment on Carbon Fibre Reinforced Polymers (CFRPs), at Diamond Lightsource. This was the first micro-scale quantification of micro-scale lattice strain in carbon fibre. This work determines the effect of load has on the axial and longitudinal strain of turbostratic atomic structure of the composite material.

Transport, Behaviour and Society

Climate anxiety: What predicts it and how is it related to climate action?

Journal of Environmental Psychology
Student: Lois Player
Cohort: Cohort 2
Date: 02 09 2022

Lois Player, AAPS CDT student, co-authors a study that finds that whilst climate anxiety is low amongst the UK public, it may be an important driver of climate action such as cutting down on waste.

The study published in the Journal of Environmental Psychology coincides with a new briefing paper from the Centre for Climate Change & Social Transformations focused on UK public preferences for low-carbon lifestyles. Its analysis suggests that lifestyle changes (for example, reducing car use or eating less meat), are increasingly seen as both feasible and desirable.

In the paper, the authors emphasise the importance of the media as a motivating force for the lifestyle changes required as we decarbonise. They suggest that the media and public discourse about climate anxiety has the power to create a positive vision for a greener, cleaner future which is significantly less dependent on fossil fuels.

Lois explained: “Our results suggest that the media could play an important role in creating positive pro-environmental behaviour change, but only if they carefully communicate the reality of climate change without inducing a sense of hopelessness.”

© Copyright 2021 AAPS CDT, Centre for Doctoral Training in Advanced Automotive Propulsion Systems at the University of Bath