Director of Research
Academic Division: Energy, Fluid Mechanics and Turbomachinery
Research group: Energy (Head of Group)
My major research theme has been related to high frequency response emission sampling systems. The context for this research was the realization in the 1970’s that air quality was being significantly affected by vehicle emissions, resulting in legislation forcing a completely new research activity for the automotive industry. By the mid-eighties, the required reductions in emissions levels had become very severe, and the component of the emissions related to engine transients became a prime focus. In 1985, my group demonstrated the first high-speed flame ionization detector system on an engine, which gave millisecond resolution of transient unburnt hydrocarbons – this was at the time the most difficult pollutant to control, especially during cold starts. I set up a company, Cambustion Ltd, which commercialized the technique, and a series of further instruments (for NOx, CO, CO2 and particulates) were developed, via a succession of PhD projects. All of these instruments were further developed by Cambustion Ltd for market, and in production form these instruments are used routinely by the automotive industry and academic research groups worldwide.
Closely associated with this topic has been my work with engines and emissions aftertreatment systems themselves. Based on a close liaison with Ford, funding was obtained for a succession of projects, initially entirely related to gasoline engines. In the early nineties, we discovered a very effective way of nearly eliminating cold start emissions, by afterburning, in front of a catalyst, rich combustion products from the engine. At the time, this was the only proven method of meeting the legislated emission levels required. Though this system did not reach production, it had a significant impact in driving other competitive technologies.
Another major theme has been engine control itself. Via collaboration with Professor Keith Glover, a series of projects have been pursued, where the theme has been the synergism of advanced control techniques (partly developed by Glover) and advanced measurement techniques. Many of the problems of engine control concern transient operation, and involve situations where pleasing the driver and the environment are nearly always mutually contradictory. Though the industry is perhaps somewhat slow in embracing some of the concepts that have been worked on, useful contributions have been made in this area. One recent “spin off” from this work has been the development of simple high speed gas sampling valves, that has enabled us to look at the cylinder contents cycle by cycle, and determine the success of an air path controller optimized for emissions reduction.
More in the present, my work on the measurement of ultra-fine particles, especially related to IC engine emissions led to a PhD project that has just finished. This was an investigation into a device that measured particle number but only solid particles (as required by recently enacted EU legislation for road vehicles). The concept was for a new type of condensation particle counter (CPC). The diameter of combustion-generated particles is well below the wavelength of visible light, which makes them very difficult to detect. The CPC grows these particles by exposing them to a super-saturated vapour environment, causing them to grow to a size that can be detected by optical light scattering. Unfortunately the standard CPC (which operates at near to room temperature) also detects volatile particles (typically consisting of sulfuric acid and unburnt hydrocarbons). Via an examination of the properties of a series of candidate high-temperature fluids, and their incorporation into a heat/mass transfer model, a prototype CPC able to operate at over 300 °C was built and successfully tested.
Finally, I have a continuing interest in the development and use of fast oxygen sensors for IC engine applications. These sensors, based on UEGO technology, can give a response time of ~ 10ms, which makes them suitable for cycle by cycle engine measurements. One immediate application to NOx emissions control, as the inlet oxygen concentration scales closely with this pollutant. My co-workers and I have also published work describing the operation of UEGO sensors.
Energy, transport and urban infrastructure
Pollution from IC Engines, fuel economy, IC engine sensors.
- Control of Engine/turbocharger interaction for best transient behaviour
- High Temperature Condensation Particle Counters
- Experimental Investigation of gas flows in Engine Induction Systems
Thermodynamics, Heat Transfer, IC Engines
I am unable to take Research Students, as I am nearing retirement.
- Head of Division A: Energy, Fluid Mechanics and Turbomachinery
- Champion for the Energy @ Cambridge strategic initiative