Dirty work

Particulate sensors that allow automatic cleaning of filters in diesel exhaust emission control systems have been developed in an EU-backed research project — the IMITEC initiative.

Diesel vehicles are increasingly becoming a major force in Europe’s automotive market, representing more than 50 per cent of the car fleet in several EU countries. They are more efficient than equivalent petrol versions but produce higher emissions of particulates, mainly carbon and nitrogen oxides.

To control this, diesel vehicles can be fitted with a particulate filter. As the filter becomes clogged by the particulate it collects, it needs to be cleaned by oxidation of the accumulated soot to remain functioning — a process known as regeneration. To do this, the exhaust temperature must be raised.

However, diesel engines are very efficient so the normal exhaust temperature is too low to oxidise soot. Without a sensor it can be hard to judge when a filter needs to regenerate, as more or less particulates can be produced depending on driving conditions.

The IMITEC sensor platform automatically judges when the filter starts to become clogged, and activates regeneration, potentially leading to fuel savings and increased reliability of the emission control system.

When IMITEC is fitted, sensors measure the values of particulates, as well as the temperature and pressure levels in the exhaust. The software component of the system uses measurements from these and then calculates values depending on the readings. The results are used by the Engine Control Unit to adaptively and efficiently manage the emission control system.

A demonstrator has been fitted into a Fiat Ducato, and should meet the anticipated Euro V emission standards — expected to be finalised by the end of this year.

According to IMITEC’s developers, the sensors could enable a multi-billion European market in emission control systems by 2010, and will help Europe meet its Kyoto Protocol CO2 obligations.

The IMITEC team may also use the technology to develop a portable unit for use in garages to aid repairs and system monitoring.

‘By 2010 almost all diesel passenger cars sold in Europe will have a type of IMITEC-like emission control system,’ claimed Dr Athanasios Konstandopoulos, director of the Aerosol and Particle Technology Laboratory at CERTH/CPERI in Thessaloniki, Greece, and coordinator of the IMITEC project.

‘In the short to medium term, hybrids cost too much and I cannot see how people will buy them. Hydrogen-powered vehicles still have a long and uphill way ahead of them; fuel cell technology problems, hydrogen transport/storage and of course where will the hydrogen come from, without CO2 emissions?’

The £2.6m project received around £1.2m from the EU under its Fifth Framework programme. The remainder came from industry partners including Fiat, UK catalyst specialist Johnson Matthey, AVL and Bosch.