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Experimental assessment of nitrogen oxides transformations while sampling combustion products. Interim scientific report

Technical Report ·
OSTI ID:5166287
Analysis of combustion products is performed by conveying the exhaust effluents to instrumentation by means of a sample probe and sampling line. Frequently, the selection of sampling materials does not consider potential chemical transformations that can occur in the sample line and probe. Nitrogen oxides are combustion products that are especially vulnerable to transformations. Nitric oxide (NO) and nitrogen dioxide (NO2) are the primary components of NOx. The ratio of NO/NO2 emissions from combustion sources is not well established (due to the potential reduction of NO2 to NO in sample probes and sample lines) and the total emission of NOx is subject to uncertainty in some cases (due to potential removal of NOx in sample probes and sample lines). The objective of the present study is to investigate the extent of transformations of NOx in the presence of oxidizing and reducing species. Stainless steel and silica were the two sampling tube materials used in this investigation. Simulated combustion products of 500 ppm NO, 75 ppm NO2, 12% CO2 bal N2 at 25 C were common to all tests. The oxidizing species and concentrations considered included 1 and 5% O2. Various concentrations of carbon monoxide, hydrogen, and hydrocarbons were used for the reducing species. Temperature and pressure effects were evaluated in this particular study. The reults indicated that transformation was more pronounced in stainless steel than silica.
Research Organization:
California Univ., Irvine (USA). Combustion Lab.
OSTI ID:
5166287
Report Number(s):
AD-A-078090
Country of Publication:
United States
Language:
English