Measurement of Automobile Exhaust N2O by Mid-IR Laser Spectroscopy

By: Kenji HARA, Montajir RAHMAN

10 May 2013

Nitrous Oxide (N2O) emission reduction has gained large prominence recently due to its contribution to the climate change as a greenhouse gas. The United States Environment Protection Agency (EPA) together with the United States Department of Transport (DOT) has already regulated the N2O emissions from Light-Duty Vehicles (LDV). For LDV, N2O measurement should be done from sample storage bags over the light-duty FTP drive cycles. N2O emission standard of 0.10 g/bhp-hr for Heavy-Duty Engines (HDE) is also finalized. The final N2O standard becomes effective in 2017 model year for diesel engines. Usually raw or diluted exhaust is measured for HDE emission testing. Therefore, an analyzer capable of measuring N2O from bag and from diluted sample continuously is required to support both LDV and HDE regulations. In this study, comparative measurement of automobile exhaust N2O in continuous dilute and in sample storage bag has been attempted. A modern vehicle meeting 2008 Japanese emission standards has been evaluated. In this letter, it is found that the laser based exhaust gas analyzer has sufficient detection capability for bag measurement and fast response for continuous dilute measurement.

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