| 摘要 |
The present invention is a method and apparatus for measuring the total NO<SUB>x </SUB>concentration in a gas stream utilizing the principles of a NO<SUB>x </SUB>sensor, i.e., mixed potential sensor. The exhaust gas is first conditioned by a catalyst assembly that converts the various species of nitrogen oxide gases present to a fixed steady state concentration ratio of NO<SUB>2</SUB>/NO, where NO<SUB>2 </SUB>is approximately 0-10% of the total NO<SUB>x </SUB>concentration present in the gas exhaust, thereby enabling the NO<SUB>x </SUB>sensor to generate a meaningful and reproducible determination of the concentration of total NO<SUB>x </SUB>present in the gas being measured. The catalyst assembly also functions to oxidize any unburned combustibles such as CH<SUB>4</SUB>, CO, etc., and remove potential contaminants such as SO<SUB>2</SUB>.
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