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The UK government offered a tax incentive to introduce ultra-low sulphur diesel (ULSD) fuels into the market place. This has led rapidly to the use of such a fuel with a consequent reduction in emissions, notably particulates and permits the use of some exhaust after-treatment devices that were formerly precluded. A water-blend fuel technology has been developed to substantially reduce engine out emissions relative to ULSD and is currently under market evaluation. Use of the fuel requires no engine modifications. To further evaluate the emissions performance of the technology, a trial was conducted with the Millbrook testing facility, Bedfordshire, England. The trial also considered the impact of such water-blend fuels on existing/future exhaust emission control technology. On the Millbrook London Transport Bus (MLTB) cycle, the water-blend fuels tested achieved significant reductions in nitrogen oxides (NOx) and particulates over that attained by ULSD.

Current Heavy Duty testing is performed almost exclusively on engine dynamometers. The limitations of this method to obtain detailed emission data for heavy duty vehicles operating in the field are widely known. The wide variety of vehicles into which an engine type may be fitted and the disparate operating conditions that the vehicle is then subject to, mean that the real environmental impact of heavy duty vehicles can never be established. A Variable Temperature Emissions Chamber (VTEC) has been developed and used for chassis dynamometer testing of numerous road vehicles right up to Double Decker Buses. This facility enables accurate emissions data to be measured for specific vehicles in their real operating environments. The facility is equipped to simulate ambient temperatures from -30°C to + 50°C and with a high volume, speed tracking air flow. Driving cycles have been developed for buses and trucks, both from detailed on-road data logging and from simulated operations.