Overview of fuel-efficient, low-emission internal combustion engines.
Despite the projected future dominance of electric vehicles in many areas of the market, liquid hydrocarbon fuels will continue to be an important part of the energy supply for road transport, in particular for high-mileage applications. Current estimates suggest that internal combustion engine (ICE) vehicles will account for approximately 50% of the total 2050 road transportation energy usage. It is therefore essential that ICE research and development is maintained, and that it is focussed on technological measures to simultaneously increase fuel economy and reduce emissions.
Flow Metering Challenges
Modern ICE vehicles (whether gasoline or diesel powered) routinely use high-pressure, fuel injection systems and complex and varied fuel injection strategies. For maximum benefit, these strategies should be applied to the engine on a cycle-by-cycle, cylinder-by-cylinder basis. However, it is not currently possible to measure the fuel flow rate in an individual injection event ( ~ 1 ms duration), either in real time or on an engine nor is it possible to detect or correct for the on-engine effects of injector-to-injector variability. Poor or degraded injector performance in one cylinder, due to manufacturing tolerances, ageing, or internal fouling, is likely to dominate the total vehicle emissions.
Modern Coriolis flow meters offer the potential for direct mass metering, but engine manifolds are a very challenging environment. There will be vibrations, electrical noise, pulsating flows and very high transient pressures (up to 3,000 bar). In addition, measurement update rates must be increased from typically 10 Hz to 50 kHz. Advanced data processing techniques, such as the PRISM filtering method developed by Professor Henry and his team at the University of Oxford, will be required, as well as appropriate flow measurement calibration systems.
The aim of this project, supported by BEIS through the Flow Programme, is to develop high-pressure, low-flow calibration infrastructure necessary to undertake the research on Coriolis meters. It is also very likely that additional infrastructure and techniques may be required to provide information on the effects of very high pressure on fluid properties, for example, to detect the onset of pressure-induced freezing.
In the first phase of the project, the User Requirement Specification (URS) for traceable calibration of Coriolis flow meters for transient, low-flow rate, high-pressure applications were determined. Professor Henry and his team are now working to identify a number of possible concepts capable of meeting the requirements given in the URS. From these, a preferred design will be recommended and detailed planning and costing will commence.
For more on the subject, please contact Principle Investigator Dr Norman Glen here.
Find out more about the work being carried out by University of Oxford here.