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NOx

About: NOx is a research topic. Over the lifetime, 26367 publications have been published within this topic receiving 496555 citations.


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Journal ArticleDOI
TL;DR: In this article, a chemical mechanism was developed to predict O3 formation in mixtures of isoprene, α-pinene and NOx in air, and the mechanism was tested against 17 outdoor smog chamber data sets from the University of North Carolina chamber and was shown to predict maximum O3 concentrations within ±20%.

130 citations

Journal ArticleDOI
TL;DR: The peculiar mixed-phase structure of TiO(2), evidenced from Raman, x-ray diffractometry (XRD), and UV-vis spectroscopy, was inferred to be an important factor for visible- light absorption and NO(x) removal activity under a wide range of visible-light illumination.
Abstract: Ultraviolet- and visible-light-responsive titania-based photocatalysts were synthesized and employed in the photocatalytic oxidation of NOx. Sol–gel processes using tetrabutyl orthotitanate and ethanol under acid catalyzed condition and controlled calcination were performed to synthesize titanium dioxide with a mixed crystal lattice of anatase, brookite and rutile phases. The TiO2 prepared under calcination at 200 °C exhibited high photocatalytic activity for degradation of NOx under both ultraviolet (UV) and visible-light illumination. The experimental results showed that up to 70% removal of NOx could be obtained in a continuous flow type reaction system under irradiation with visible light. The calcination temperature has an important influence on the particle size and lattice structure of TiO2. It is also found that the peculiar mixed-phase structure of TiO2, evidenced from Raman, x-ray diffractometry (XRD), and UV–vis spectroscopy, was inferred to be an important factor for visible-light absorption and NOx removal activity under a wide range of visible-light illumination.

130 citations

Patent
02 Oct 1992
TL;DR: In this paper, the authors describe a system in which NOx absorbent (18) absorbs NOx when an air-fuel ratio of exhaust gas flowing into said absorbent is lean and discharges NOx having been absorbed therein.
Abstract: NOx absorbent (18) is disposed in the exhaust gas path in the internal combustion engine and exhaust gas is adapted to flow constantly through said absorbent (18) during the operation of said engine. NOx absorbent (18) absorbs NOx when an air-fuel ratio of exhaust gas flowing into said absorbent (18) is lean and, when an air-fuel ratio of exhaust gas becomes equal to the theoretical air-fuel ratio or rich, it discharges NOx having been absorbed therein. Over almost the entire range of operation of the engine, lean mixed gas is burnt in the combustion chamber (3) and NOx generated at this time is absorbed by said absorbent (18). An air-fuel ratio of exhaust gas flowing into the NOx absorbent (18) is periodically made equal to the theoretical one or rich and NOx having been absorbed by the absorbent (18) is discharged and reduced at the same time.

130 citations

Proceedings ArticleDOI
16 Oct 2000
TL;DR: In this paper, the effects of in-cylinder water injection on a direct injection (DI) Diesel engine were studied using a computational fluid dynamics (CFD) program based on the Kiva-3v code.
Abstract: The effects of in-cylinder water injection on a direct injection (DI) Diesel engine were studied using a computational fluid dynamics (CFD) program based on the Kiva-3v code. The spray model is validated against experimental bomb data with good agreement for vapor penetration as a function of time. It was found that liquid penetration increased approximately 35% with 23% of the fuel volume replaced by water, due mostly to the increase in latent heat of vaporization. Engine calculations were compared to experimental results and showed very good agreement with pressure, ignition delay and fuel consumption. Trends for emissions were accurately predicted for both 44% and 86% load conditions. Engine simulations showed that the vaporization of liquid water as well as a local increase in specific heat of the gas around the flame resulted in lower Nitrogen Oxide emissions (NOx) and soot formation rates. Using stratified fuel-water injection increases soot at 86% loads due in part to late injection. Because NOx decreased at all loads, the injection timing can be advanced to minimize fuel consumption and soot.

130 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive test of nocturnal nitrogen oxide chemistry, concentrations of O3, NO, NO 2, NO2, NO3, N2O5, HNO3 and other relevant compounds, aerosol abundance and composition, and meteorological conditions were measured in the marine boundary layer from the NOAA research vessel Ronald H. Brown off the East Coast of the United States as part of the New England Air Quality Study (NEAQS) during the summer of 2002.
Abstract: [1] The nitrate radical, NO3, and dinitrogen pentoxide, N2O5, are two important components of nitrogen oxides that occur predominantly at night in the lower troposphere. Because a large fraction of NO2 reacts to form NO3 and N2O5 during the course of a night, their fate is an important determining factor to the overall fate of NOx (=NO and NO2). As a comprehensive test of nocturnal nitrogen oxide chemistry, concentrations of O3, NO, NO2, NO3, N2O5, HNO3 and a host of other relevant compounds, aerosol abundance and composition, and meteorological conditions were measured in the marine boundary layer from the NOAA research vessel Ronald H. Brown off the East Coast of the United States as part of the New England Air Quality Study (NEAQS) during the summer of 2002. The results confirm the prominent role of NO3 and N2O5 in converting NOx to HNO3 at night with an efficiency on par with daytime photochemical conversion. The findings demonstrate the large role of nighttime chemistry in determining the NOx budget and consequent production of ozone.

130 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20231,699
20223,249
20211,405
20201,353
20191,367