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1.
Experiments in dc supplied corona discharge in natural gas + air mixture and in combustion exhaust of natural gas + air mixture were realized. The influence of discharge on CO, CO2, NO
x
and other minority components was studied using IR absorption spectrometry. Production of NCO radicals in gas and consequent formation of NCO containing surface layers on a plate electrode was detected. In natural gas + air mixture after about 1 min oxygen poor combustion exhaust was produced due to slow combustion by corona discharge. Occurrence of various pulses in discharge current was typical. 相似文献
2.
R. Evertsen A. Staicu N. Dam A. van Vliet J.J. ter Meulen 《Applied physics. B, Lasers and optics》2002,74(4-5):465-468
The application of pulsed cavity ring-down spectroscopy has been demonstrated for the in situ quantitative determination
of NO and NO2 in the exhaust of a diesel engine. NO absorption has been monitored at the transition from the Χ2Π ground state to the A2Σ+ state at 226 nm. For NO2, absorption bands in the spectral region from 438 nm to 450 nm were used. At the selected engine conditions, concentrations
of 212±22 ppm and 29±4 ppm have been measured for NO and NO2, respectively, in good agreement with separate chemical exhaust gas analysis. The method is sensitive enough to meet the
European Euro V standard directive on NOx emissions. This communication discusses the relatively simple setup needed for this type of measurement, the problems encountered,
as well as the prospects for single-stroke, simultaneous measurements of both NO and NO2 at the sub-ppm level.
Received: 30 November 2001 / Revised version: 18 February 2002 / Published online: 14 March 2002 相似文献
3.
Christopher R. Shaddix Alejandro Molina 《Proceedings of the Combustion Institute》2011,33(2):1723-1730
NOx formation was measured during combustion of pulverized coals and pulverized coal char in N2 and CO2 environments under isothermal and nearly constant oxygen conditions (i.e. using dilute coal loading). Three different oxygen concentrations (12% O2, 24% O2, and 36% O2) and two representative US coals were investigated, at a gas temperature of 1050 °C. To investigate the importance of NO reburn reactions, experiments were also performed with an elevated concentration (550 ppm) of NO in the gases into which the coal was introduced. For low levels of background NO, the fractional fuel-nitrogen conversion to NOx increases dramatically with increasing bath gas oxygen content, for both N2 and CO2 environments, though the fuel conversion is generally lower in CO2 environments. Char N conversion is lower than volatile N conversion, especially for elevated O2 concentrations. These results highlight the importance of the volatile flame and char combustion temperatures on NOx formation. For the high background NOx condition, net NOx production is only observed in the 36% O2 environment. Under these dilute loading conditions, NO reburn is found to be between 20% and 40%, depending on the type of coal, the use of N2 or CO2 diluent, the bulk O2 concentration, and whether or not one considers reburn of volatile-NOx. This dataset provides a unique opportunity to understand and differentiate the different sources and sinks of NOx under oxy-fuel combustion conditions. 相似文献
4.
I. Ventrillard-Courtillot E. Sciamma O’Brien S. Kassi G. Méjean D. Romanini 《Applied physics. B, Lasers and optics》2010,101(3):661-669
In the past decade, due to a growing awareness of the importance of air quality and air pollution control, many diagnostic
tools and techniques have been developed to detect and quantify the concentration of pollutants such as NO
x
, SO
x
, CO, and CO2. We present here an Incoherent Broad-Band Cavity-Enhanced Spectroscopy (IBB-CEAS) set-up which uses a LED emitting around
625 nm for the simultaneous detection of NO2 and NO3. The LED light transmitted through a high-finesse optical cavity filled with a gas sample is detected by a low resolution
spectrometer. After calibration of the spectrometer with a NO2 reference sample, a linear multicomponent fit analysis of the absorption spectra allows for simultaneous measurements of
NO2 and NO3 concentrations in a flow of ambient air. The optimal averaging time is found to be on the order of 400 s and appears to be
limited by the drift of the spectrometer. At this averaging time the smallest detectable absorption is 2×10−10 cm−1, which corresponds to detection limits of 600 pptv for NO2 and 2 pptv for NO3. This compact and low cost instrument is a promising diagnostic tool for air quality control in urban environments. 相似文献
5.
We investigate the removal of air pollutants containing nanoparticles with a wet-type plasma reactor that generates a gas-liquid interfacial nonthermal plasma. To evaluate the performance of this reactor, we prepare a simulated exhaust gas using polystyrene latex particles, as well as gas cylinders of synthesized air and mixed gas of nitric oxide (NO) and sulfur dioxide (SO2). We achieve a partial collection efficiency of more than 99% for nanoparticles. Moreover, we obtain removal efficiencies exceeding 99% and 81% for SO2 and NOx, respectively. We confirm that the proposed reactor is useful for the simultaneous removal of nanoparticles, NOx, and SOx. 相似文献
6.
Oliver Diemel Rene Honza Carl-Philipp Ding Benjamin Böhm Steven Wagner 《Proceedings of the Combustion Institute》2019,37(2):1453-1460
We present a multi-species mole fraction and temperature sensor for in situ exhaust gas diagnostic of internal combustion (IC) engines. The sensor is based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) and incorporates four optical channels - two miniature White cells and two double-traversal cells - with base lengths of 6?cm. It has been demonstrated at a hot air test stand and in the exhaust manifold of a single-cylinder research engine, with measured temperatures of up to 1000?K. Stable operation was achieved with absorption lengths of up to 192?cm (test stand) and 97?cm (engine). Employing time-division multiplexed detection, six species were measured simultaneously in the engine exhaust, at wavelengths ranging from 1.4?µm to 5.2 µm: water vapor (H2O), carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), nitrogen dioxide (NO2) and nitric oxide (NO). The effective measurement rate was as high as 1?kHz, and cycle-to-cycle variations were clearly detected. We show the correlation of the air-fuel equivalence ratio with the spectroscopically measured mole fraction of each species. At a cycle-resolved rate, detection limits for the legally regulated species NO and NO2 were 1?ppm and 4?ppm, respectively. The sensor is intended to help improve the understanding of IC engine emission behavior during fast transients. 相似文献
7.
R. Barron-Jimenez J.A. Caton T.N. Anderson R.P. Lucht T. Walther S. Roy M.S. Brown J.R. Gord 《Applied physics. B, Lasers and optics》2006,85(2-3):185-197
An all-solid-state continuous-wave (cw) laser system for mid-infrared absorption measurements of the carbon monoxide (CO) molecule has been developed and demonstrated. The single-mode, tunable output of an external-cavity diode laser (ECDL) is difference-frequency mixed with the output of a 550-mW diode-pumped cw Nd:YAG laser in a periodically poled lithium niobate (PPLN) crystal to generate tunable cw radiation in the mid-infrared region. The wavelength of the 860-nm ECDL can be coarse tuned from 860.782 to 872.826 nm, allowing the sensor to be operated in the spectral region 4.4–4.8 μm. CO-concentration measurements were performed in CO/CO2/N2 mixtures in a room-temperature gas cell, in the exhaust stream of a well-stirred reactor (WSR) at Wright-Patterson Air Force Base and in a near-adiabatic hydrogen/air CO2-doped flame. The noise equivalent detection limits were estimated to be 1.1 and 2.5 ppm per meter for the gas cell and flame experiments, respectively. These limits were computed for combustion gas at 1000 K and atmospheric pressure assuming a signal-to-noise ratio of 1. The sensor uncertainty was estimated to be 2% for the gas-cell measurements and 10% for the flame measurements based on the repeatability of the peak absorption. PACS 07.07.Df; 42.62.Fi; 42.65.Ky; 42.72.Ai 相似文献
8.
Stabilized zirconia-based electrochemical devices for which the sensing electrode was provided with a single-metal oxide were
tested for NO and NO2 sensing properties at high temperature. Among the many single-metal oxides examined, WO3 was found to give the best sensing properties to NO and NO2 at 500–700°C. The EMF response of the WO3-attached device was linear to the logarithm of NO or NO2 concentration. The response and recovery kinetics were speedy. The device gave very small cross-sensitivities to H2, CO, CH4, CO2 and water vapor. The sensing mechanism involving mixed-potential was confirmed from the measurements of polarization curves. 相似文献
9.
An experimental study on the production of NOx as a function of dissipated energy in laser-produced plasma in air is presented. A plasma was produced by focusing a (60–180) mJ, 5 ns, 532 nm pulse from a Q-switched Nd:YAG laser. The results show that for laser energy in the range of 13–99 mJ the laser plasma generates 6.7×1016 NOx molecules per joule and 4.6×1016 NO molecules per joule. An order of magnitude estimate of the NO and NOx production per unit volume of heated gas based on a simple model show that the NOx and NO production efficiency in air are about 3×1022 and 2×1022 molecules J−1 m−3. 相似文献
10.
Selective catalytic reduction (SCR) of NOx is one of the important strategies in regulating NOx emissions. In the past several decades, the reactions of NOx (mainly NO) with H2, CO, NH3 and hydrocarbons have been extensively investigated under ambient conditions and have been summarized in numerous reviews. Nonetheless, many questions appear to be difficult to answer under ambient conditions, e.g., the pathways through which the reactions proceed. The introduction and development of modern surface science technology has played an indispensable role and is widely employed in the studies of the SCR of NOx, greatly helping to elucidate the mechanisms of the reactions with CO, H2, and NH3. However, so far, there are few review papers systematically summarizing the progress of such studies.Recently, systematic surface science studies have been conducted on the mechanisms of SCR of NO with organic molecules including ethylene, benzene, and ethanol, which are much more complicated than those with H2, CO and NH3 and have drawn much less attention before. It is confirmed that these reactions can be reliably and most importantly, reproducibly probed by surface science technology, but a great deal of work remains to be done.Since Delmon et al. have provided a very thorough review of the researches on catalytic removal of NO (reactions with H2, CO and NH3) up to 1998, in which the reactions conducted both under ambient and UHV conditions were included, this review mainly concentrates on the progress made since 1998. 相似文献
11.
Y. Yamamoto H. Sumizawa H. Yamada K. Tonokura 《Applied physics. B, Lasers and optics》2011,105(4):923-931
The application of pulsed cavity ring-down spectroscopy (CRDS) was demonstrated for the measurement of nitrogen dioxide (NO2) in automotive exhaust gas. The transition of the ν
3 vibrational band assigned to the antisymmetric stretching mode of NO2 was probed with a thermoelectrically cooled, pulsed, mid-infrared, distributed feedback, quantum cascade laser (QCL) at 6.13 μm.
The measurement of NO2 in the exhaust gas from two diesel vehicles equipped with different aftertreatment devices was demonstrated using a CRDS-based
NO2 sensor, which employs a HEPA filter and a membrane gas dryer to remove interference from water as well as particulates in
the exhaust gas. Stable and sensitive measurement of NO2 in the exhaust gas was achieved for more than 30 minutes with a time resolution of 1 s. 相似文献
12.
R.K. Hanson J.P. Monat C.H. Kruger 《Journal of Quantitative Spectroscopy & Radiative Transfer》1976,16(8):705-713
Absorption of CO i.r. laser radiation by NO has been studied over the temperature range 300°–4000°K using a grating-tunable CO laser in conjunction with a room-temperature absorption cell and a shock tube. The CO laser line with strongest absorption at elevated temperatures was determined to be the V = 7 → 6, J = 12 → 13 line at 1935.4817 cm-1, which is nearly coincident with the 2ΠV = 0 → 1, J = 37/2 → 39/2 transition in NO. The absorption cell measurements (300°K) were used to infer the position of the NO absorption line (a Λ-doublet at 1935.492 and 1935.497 cm-1) as well as collision-broadening parameters in pure NO and NO dilute in foreign gases: 2γ° (collision-broadened full width at half maximum in cm-1 atm-1 at 300°K) = 0.110, NO-NO; 0.072, NO in Ar; 0.069, NO in Kr; 0.109, NO in N2. Calculations of the NO absorption coefficient at 1935.4817 cm-1 are presented for a range of conditions applicable to current studies in combustion and NOx kinetics. Shock tube measurements (630°–4000°K) supporting these calculations are also reported. 相似文献
13.
I. A. Zubrilin S. G. Matveev A. Marrone D. G. Pastrone 《Bulletin of the Lebedev Physics Institute》2018,45(10):308-310
The results of simulation of the NOx and CO formation in a small-sized gas turbine engine are presented. A comparison of the results of CFD calculations with experimental data showed that calculations in standard three-dimensional formulation in combination with partitioning into a network of reactors can be used to simulate NOx and CO formation. When using the JetSurf 2.0 chemical reaction mechanism, satisfactory agreement between calculated and experimental data is achieved with a number of elementary reactors above several hundreds. 相似文献
14.
N. Savastenko H.-R. Volpp O. Gerlach W. Strehlau 《Journal of nanoparticle research》2008,10(2):277-287
Monometallic Pt and Rh and bimetallic PtRh catalysts with a highly dispersed noble metal weight loading of ca. 1 wt% were
produced via the direct deposition of nanoparticles on different SiO2 supports by means of pulsed ultra-violet (248 nm) excimer laser ablation of Pt, Rh bulk metal and PtRh alloy targets. Backscattered
electron microscopy (BSE), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were employed
to characterize the deposited nanoparticles, which were found to exhibit narrow size distribution centred around 2.5 nm. The
catalytic activities for lean NO
x
reduction of the monometallic and bimetallic catalyst samples were investigated in a flow reactor setup in the temperature
range 100–400°C using a test gas mixture representative of oxygen rich diesel engine exhaust gas. For comparison a Rh/SiO2 reference catalyst prepared by a conventional impregnation method was also tested. Further experiments were performed in
which PtRh nanoparticles were deposited on a Rh/SiO2 reference catalyst sample to study the possibility for controlled modification of its activity. The catalytic activity measurements
revealed that among the samples solely prepared by laser deposition the PtRh–SiO2 nanoparticle catalyst showed the highest activity for NO
x
reduction at low temperatures 100–300°C. In addition, it could be demonstrated that the initially low NO
x
reduction activity and the N2 selectivity of the Rh/SiO2 reference catalyst sample for temperatures below 250°C can be enhanced by post laser deposition of PtRh nanoparticles. 相似文献
15.
The object of this experimental investigation was the influence of temperature and humidity on the efficiency of removal of
NO
x
by a pulsed corona discharge from a mixture N2 : O2 : CO2 : H2O : NO simulating a combustion flue gas. The pulsed corona discharge was generated in a wire-to-cylinder reactor. It was found
that removal of NO
x
was most efficient when H2O concentration corresponded with the saturated vapour pressure. In the case of the operating gas containing constant H2O concentration removal of NO
x
decreased with increasing temperature of the operating gas.
Dedicated to Prof. Jan Janča on the occasion of his 60th birthday.
This work is devoted to the 60th birthday of Professor Jan Janca, our good colleague, merited teacher, researcher and famous physicist, discussion with whom
stimulated this and other our work during years. 相似文献
16.
S. V. Ivanov 《Physics of Wave Phenomena》2007,15(1):57-65
Using the technique of limiting information-metric scales, the potential of laser IR absorption spectroscopy for detecting
small gas components of aircraft wake was quantitatively analyzed. Formulas for minimum distinguishable and minimum detectable
gas concentrations were derived. Calculation was carried out for SO2, NO, and NO2 under typical conditions near the Boeing 707 aircraft engine nozzle at altitude H = 12.2 km. Alternative IR laser spectroscopy methods for detecting various gas components in the near wake were considered.
Two possibilities to improve the concentration measurement sensitivity were analyzed: (i) a decrease in the background absorption
of CO2 and H2O and (ii) an increase in the absorption cross section of detected gas. 相似文献
17.
Cross-interference correction and simultaneous multi-gas analysis based on infrared absorption
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In this paper, we present simultaneous multiple pollutant gases (CO 2 , CO, and NO) measurements by using the non-dispersive infrared (NDIR) technique. A cross-correlation correction method is proposed and used to correct the cross-interferences among the target gases. The calculation of calibration curves is based on least-square fittings with third-order polynomials, and the interference functions are approximated by linear curves. The pure absorbance of each gas is obtained by solving three simultaneous equations using the fitted interference functions. Through the interference correction, the signal created at each filter channel only depends on the absorption of the intended gas. Gas mixture samples with different concentrations of CO 2 , CO, and NO are pumped into the sample cell for analysis. The results show that the measurement error of each gas is less than 4.5%. 相似文献
18.
Infrared reflection absorption spectroscopy together with mass spectrometry has been used to investigate the interaction of NO and CO on Pt{1 0 0}, initially prepared in the reconstructed ‘hex’ phase, under ambient pressures of these gases, in the temperature range 300-500 K. The results allow the local and total coverages of adsorbed CO and NO to be related to the rate of reaction to produce gas phase CO2, and provide insight into the species present on the surface during the so-called low temperature oscillatory reaction regime of this process. At temperatures below that at which NO dissociation occurs (approximately 390-400 K) adsorption is controlled by the non-reactive displacement of NO by CO and results in a CO-poisoned surface. Above 400 K when significant CO2 production occurs, the NO coverage increases to produce a surface with NO and CO fully intermixed; the increase in NO coverage is attributed to the higher rate of NO arrival from the gas phase (with a partial pressure ratio of PNO:PCO>1) at free surface sites created by NO dissociation and subsequent reaction with CO. The competition between these two processes of non-reactive NO displacement by CO and reactive displacement of CO by NO is proposed to determine the parameter space of the low temperature oscillatory regime. Rapid equilibration between bridged and atop CO species leads to them appearing to exhibit identical reaction behaviour. Particularly at the lowest reaction temperatures (around 400 K), islands of pure CO may coexist on the surface but not participate in the reaction. Under conditions corresponding to the high temperature oscillatory regime, small quantities of absorbed CO, but no NO, are seen on the surface. 相似文献
19.
S. Aravind R.K. Gohiya R.S. Prakash R. Sadanandan 《Proceedings of the Combustion Institute》2021,38(4):5209-5217
The effect of CO2 dilution on the flame characteristics and pollutant emission of a partially premixed CH4-air flame in a confined bluff body and swirl influenced flowfield is investigated using optical and laser diagnostic methods. The non-premixed burner produced a converging-diverging flowfield at the burner exit and a lifted flame is produced at all test cases, with an upstream movement of the flame with decreasing global equivalence ratios (?g). Based on variations in ?g, two flame stabilization modes – bluff body influenced and swirl stabilized – with a transition mode in-between is observed for the cases with (flame FB) and without dilution (flame FM). The characteristics of the heat release zone are influenced by dilution, with the FB flames being longer and also less intense when compared to FM flames. Pollutant measurement at 30 mm downstream from the combustor exit highlighted the ultra-low NOx capability of the IIST-GS2 burner. CO2 dilution leads to a reduction in NOx emission due to both thermal and chemical effects. For ?g ≥ 0.7 extreme low levels of CO and unburned hydrocarbons (UHC) are observed for both cases. For ?g ≤ 0.6 the dramatic increase of both CO and UHC maybe due to the lower flame temperatures and shorter flame zone residence times, respectively. 相似文献
20.
The adsorption behaviours of seven molecules (CO, CO2, N2, NO, O2, N2O and NO2) on Rh3X (X?=Sc-Zn, Y-Cd) clusters are systematically investigated by density-functional calculations. Rh3X clusters exhibit physical adsorption when interacting with CO2, CO, N2 and NO. The adsorption energies (Eads) can be ranked as follows: NO?>?CO?>?CO2?≥?N2. Compared with pure Rh4 cluster, the adsorption capacity changes with the doping element. Chemical adsorption can be obtained for Rh3X when adsorbing O2, N2O and NO2. Eads shows an order of Eads(O2)?>?Eads(NO2)?>?Eads(N2O). When O2 is adsorbed, energy barrier with doping Tc or Cr atom is substantially reduced, which indicates that chemical reactivity of O2 on Rh4 can be significantly enhanced. The doped rhodium clusters can be viewed as good candidates in the discrimination between different gas molecules. 相似文献