Device Could Allow Drivers to Monitor Emissions

In future drivers may only have to glance at the dashboard to see the pollution spewing out of their vehicle's exhausts.

A team from The University of Manchester has constructed a laser measuring device capable of recording levels of carbon dioxide, carbon monoxide and methane from directly inside an exhaust system, according to an Aug. 5 announcement by the university.

Once optimized, the process could be incorporated into onboard diagnostic systems that would monitor emissions as vehicles drive along -- and potentially help people reduce their emissions by adjusting their driving style.

Reporting in the Optical Society of America's journal Applied Optics, academics claim this approach is faster and more sensitive than the extractive techniques normally used to monitor emissions.

In a test, for example, exhaust emissions are extracted into a box while the engine is idling and the gases present are then measured.

The University of Manchester team employed a device known as a "near-IR diode laser sensor" to measure the variation in gas concentration during changes in the operating conditions of a Rover engine, such as increasing and decreasing the throttle, adjusting the air to fuel ratio, and start-up.

"This is the first instance of this type of near-IR diode laser sensor being used directly in the exhaust of a static internal combustion engine to measure emissions," said Dr. Philip Martin, one of the paper's authors.

The team stated that the components for the device are readily available and the near-IR technology allows highly accurate readings to be taken and also cuts out interference.

In the studies reported in Applied Optics, the near-IR device used two diode lasers operating at different frequencies; one detecting carbon monoxide and carbon dioxide and the other detecting methane.

The next steps will be to fully quantify the technique and add additional lasers for other key emissions such as nitrogen oxide, nitrogen dioxide and specific hydrocarbons.

Philip Martin: http://www.ceas.manchester.ac.uk/aboutus/staff (scroll down for link to his contact information)

This article originally appeared in the 08/01/2007 issue of Environmental Protection.

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