Demonstration of the Benefits of DPF/FBC Systems on London Black Cabs

Future emissions limits are pushing vehicle manufacturers towards the fitting of Diesel Particulate Filters (DPFs) as original equipment. However due to the replacement rate of the vehicle fleet, there is a delay before the full benefit of these measures are fully realised. To overcome this problem, in areas with a particular problem such as heavily congested city centres, retrospective legislation has been, and may be introduced. Legislation mandating the retrofitting of DPFs obviously has an immediate effect on particulate emissions. In some countries including the UK there are also fiscal incentives to fit DPFs.

Due to its duty cycle the London taxi or Black Cab is one of the more challenging areas of application for the DPF. Previous work has shown that the use of a fuel borne catalyst (FBC) can extend the operating range of DPF systems providing the possibility of a viable system for such applications. To assess the benefits of a DPF/FBC system and to demonstrate its viability on London Black Cabs a programme was undertaken using four vehicles representative of the older, “dirtier” vehicles in service. Four cars were fitted with a DPF, an on-board dosing system to meter the FBC into the fuel and a data logger to monitor the DPF performance. Emissions measurements were taken before and after fitting the DPF. The cars were then run on the road conducting normal taxi duties. After approximately 20000 km the cars were brought back for a further set of emissions measurements to be performed with the DPF fitted and again with the DPF removed.

This paper summarises two earlier papers detailing the regulated and non-regulated emissions benefits at the start of the programme and then goes on to present data from the in-service performance of the systems.