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Topic Name: a laser measuring device capable of recording levels of carbon dioxide, carbon monoxide and methane
Category: Optoelectronics
Research persons: Y. Gérard, R. J. Holdsworth, and P. A. Martin
Location: The University of Manchester, Sackville Street Building, Sackville Street, Manchester, M60 1QD, UK, United Kingdom
Details
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.
Once optimised, 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 an MOT 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 say 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 team measured the emissions produced by a Rover K-series car engine
mounted on a test bed – but they have also taken the process outside the
laboratory and measured exhaust emissions in passing vehicles.
“Components handling the high sensitivity and robustness required to apply
this approach in the real world are only now becoming available,” added Dr
Martin. “We have already constructed a battery-powered roadside unit using the
same technology, employing rugged and robust telecommunications components.”
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.
Abstract
A multispecies near-infrared diode laser spectrometer has been constructed for
measurements of carbon monoxide, carbon dioxide, and methane directly in the
exhaust of a static internal combustion engine. A wavelength modulation-division
multiplexing scheme was implemented for the two distributed feedback diode
lasers. Gas concentration variations were observed for changes in operating
conditions such as increasing and decreasing the throttle, adjusting the
air-fuel ratio, and engine start-up.
About Researcher:
Philip A .Martin
Dr Martin, who is a co-founder of University spin-out company TDL Sensors,
says the technology could also potentially be used in roadside congestion
charging systems, with less polluting vehicles being charged less.
School/Division : School of Chemical Engineering & Analytical Science
Section : School of Chemical Engineering & Analytical Science
Role : Senior Lecturer
Email : Philip.Martin@manchester.ac.uk
Funded:
The work was partly funded by the
European Framework 5 project Advanced Laser
Sensor Systems for Leading Edge Manufacturing.
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