Investigation into the Performance of an Ultra-fast Response NO Analyser Equipped with a NO2 to NO Converter for Gasoline and Diesel Exhaust NOx Measurements
Date Published: 2000-10-16
Paper Number:2000-01-2954
DOI: 10.4271/2000-01-2954
Citation:
Collier, T., Gregory, D., Rushton, M., and Hands, T., "Investigation into the Performance of an Ultra-fast Response NO Analyser Equipped with a NO2 to NO Converter for Gasoline and Diesel Exhaust NOx Measurements," SAE Technical Paper 2000-01-2954, 2000, doi:10.4271/2000-01-2954.
The development and optimisation of an ultra-fast response chemiluminescence NO
x
analyser, equipped with a high temperature stainless steel, nitrogen dioxide (NO
2
) to nitric oxide (NO) converter, for the transient measurement of the NO
x
(NO + NO
2
) content of automotive emissions is described. Conventional analysers routinely used to measure NO
x
in automotive exhaust utilise chemiluminescence detection (CLD). Ultra-fast time-scale analysis using CLD, however, has traditionally been hindered by the slow conversion of NO
2
to NO. The converter and technology used in the instrument described herein enables a 10-90% response time of less than 10 ms.
Following optimisation in the laboratory, the fast response CLD NO
x
analyser was evaluated for raw exhaust sampling of port fuel injected (PFI) gasoline and diesel vehicles. Conventional CLD and on-line speciation systems, such as chemical ionisation mass spectrometry (CIMS), were used to assess the effectiveness of the fast response CLD NO
x
analyser under different exhaust composition regimes.
The performance of the ultra-fast response CLD NO
x
analyser under most operating conditions was found to be excellent. An exception is the lean-burn PFI gasoline engine equipped with a close-coupled three-way catalyst (TWC) and underfloor lean NO
x
trap (LNT) where, under periodic rich purge regenerations, the ultra-fast CLD NO
x
analyser exhibits a response to interfering components associated with the NO
x
converter.
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