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1.
Five and six-temperature models for the CO2–N2–He system are used to describe the process of the dynamic emission in the TEA CO2 laser. All physical constants and relaxation rates related to these models are examined to estimate the output pulse parameters as a function of the input parameters. The two pumping processes implemented; empirical function and differential equation show a good agreement with the experimental data. 相似文献
2.
Tanh Le Cong 《Proceedings of the Combustion Institute》2009,32(1):427-435
An experimental investigation of the oxidation of hydrogen diluted by nitrogen in presence of CO2 was performed in a fused silica jet-stirred reactor (JSR) over the temperature range 800-1050 K, from fuel-lean to fuel-rich conditions and at atmospheric pressure. The mean residence time was kept constant in the experiments: 120 ms at 1 atm and 250 ms at 10 atm. The effect of variable initial concentrations of hydrogen on the combustion of methane and methane/carbon dioxide mixtures diluted by nitrogen was also experimentally studied. Concentration profiles for O2, H2, H2O, CO, CO2, CH2O, CH4, C2H6, C2H4, and C2H2 were measured by sonic probe sampling followed by chemical analyses (FT-IR, gas chromatography). A detailed chemical kinetic modeling of the present experiments and of the literature data (flame speed and ignition delays) was performed using a recently proposed kinetic scheme showing good agreement between the data and this modeling, and providing further validation of the kinetic model (128 species and 924 reversible reactions). Sensitivity and reaction paths analyses were used to delineate the important reactions influencing the kinetic of oxidation of the fuels in absence and in presence of additives (CO2 and H2). The kinetic reaction scheme proposed helps understanding the inhibiting effect of CO2 on the oxidation of hydrogen and methane and should be useful for gas turbine modeling. 相似文献
3.
Jijiang Xie Qikun Pan Ruhai GuoLaiming Zhang Peng Ruan Dianjun LiGuilong Yang Chuansheng ZhangJin Guo 《Optics and Lasers in Engineering》2012,50(2):159-164
A compacted size high power CO2 laser has been developed using an acousto-optically (AO) Q-switch. Performance characteristics have been investigated as a function of output mirror transmittance. The theory of six-temperature model for CO2 lasers has firstly been utilized to analyze the dynamical process in the AO Q-switched CO2 laser. This theory perfectly explains the behavior of energy transfer between different molecules in laser gain medium, and describes the shape of pulse laser. The calculated pulse waveforms are in good agreement with the experimental result. Both the experimental and theoretical results present that the optimal value of output mirror transmittance is 39%. Under this condition, the measured peak power is 4750 W and pulsed width is 160 ns, which is consistent with the calculations. Six-temperature model is a perfect theory for CO2 laser kinetics, which will lay a theoretical foundation for the laser optimum design. 相似文献
4.
Ethan S. Hecht Christopher R. Shaddix Alejandro Molina Brian S. Haynes 《Proceedings of the Combustion Institute》2011,33(2):1699-1706
For oxy-combustion with flue gas recirculation, as is commonly employed, it is recognized that elevated CO2 levels affect radiant transport, the heat capacity of the gas, and other gas transport properties. A topic of widespread speculation has concerned the effect of the CO2 gasification reaction with coal char on the char burning rate. To give clarity to the likely impact of this reaction on the oxy-fuel combustion of pulverized coal char, the Surface Kinetics in Porous Particles (SKIPPY) code was employed for a range of potential CO2 reaction rates for a high-volatile bituminous coal char particle (130 μm diameter) reacting in several O2 concentration environments. The effects of boundary layer chemistry are also examined in this analysis. Under oxygen-enriched conditions, boundary layer reactions (converting CO to CO2, with concomitant heat release) are shown to increase the char particle temperature and burning rate, while decreasing the O2 concentration at the particle surface. The CO2 gasification reaction acts to reduce the char particle temperature (because of the reaction endothermicity) and thereby reduces the rate of char oxidation. Interestingly, the presence of the CO2 gasification reaction increases the char conversion rate for combustion at low O2 concentrations, but decreases char conversion for combustion at high O2 concentrations. These calculations give new insight into the complexity of the effects from the CO2 gasification reaction and should help improve the understanding of experimentally measured oxy-fuel char combustion and burnout trends in the literature. 相似文献
5.
L. Wang V.I. Perevalov S.A. Tashkun A.-W. Liu S.-M. Hu 《Journal of Molecular Spectroscopy》2005,233(2):297-300
The absolute line intensities of the Fermi triad 2003i-00001 (i = 1, 2, 3) of 12C16O2 and 13C16O2 isotopic species of carbon dioxide were retrieved from Fourier-transform spectra recorded at Doppler limited resolution in the region 9200-9700 cm−1. The accuracy of the line intensity determination is estimated to be better than 15% for most lines. The vibrational transition dipole moments squared and Herman-Wallis coefficients have been determined. The global fittings of the observed line intensities within the framework of the effective operators method have been performed. The fitting results reproduce the data within experimental uncertainty. 相似文献
6.
The solid neon matrix isolated spectrum of CO2 are recorded in the 2–5 μm region. Natural and 13C or 18O enriched CO2 samples were used and the nν1 + ν3 (n = 0, 1, 2) series bands of different CO2 isotopologues have been observed. The solid neon matrix shift due to Fermi-resonance of bands within the same vibrational polyad is analyzed. 相似文献
7.
A laser spectrometer based on a continuous-wave thermoelectrically-cooled distributed feedback quantum cascade laser at ∼2308 cm−1 has been evaluated for measurement of 13CO2/12CO2 isotopic ratio (δ13C) changes in exhaled breath samples and in CO2 gas flows in the concentration range 1-5%. Mid-infrared CO2 absorption spectra were measured in a 54.2-cm long optical cell using balanced detection whereby the beam passing through the cell was ratioed against a reference beam split-off from the main beam before the cell. Signal-to-noise ratios (SNR) were estimated for CO2 concentration measurements determined from either absorption peak amplitude or absorption peak area. The highest SNR were achieved in the measurements based upon a fitted absorption peak area. Typical short-term δ13C precisions of 1.10/00 (1-s integration time) and 0.50/00 (8-12-s integration time) were estimated from the two-sample (Allan) variance plots of data recorded in the optical cell at a pressure of 20 Torr and with no active temperature stabilization of the cell and gas flow. The best precision of 0.120/00 was achieved for averaging 80 successive 1-s integration time measurements. 相似文献
8.
A mathematical model describing the dynamic emission of a single mode TE CO2 laser with saturable absorber has been adapted. A six-temperature model has been used to describe the amplifying medium, while a four-coupled energy level is used to describe the selective absorbing medium. The suggested mathematical model allows the investigation of the effects of the intracavity absorber on the mode characteristics of the TE CO2 laser and, moreover, the study of the effect of the laser input parameters on the output laser pulse. The model simulates the passive Q-switch in both low- and high-pressure cases in the absorbing medium.
In addition, numerical solutions of a non-linear rate equation system of the suggested model are quantitatively discussed. The solutions describe the photon number density, the population inversion and the energy transfer processes of amplifying and absorbing media. 相似文献
9.
Ryutaro Souda 《Surface science》2004,551(3):171-178
On the basis of the matrix effect of secondary-ion mass spectrometry (SIMS), the intermolecular interactions between D2O and hydrophobic molecules have been investigated at temperature of 15 K. The D+ yield is found to be enhanced markedly relative to the D3O+ yield when the D2O molecule forms a complex with the CO or CO2 molecules on the surface. The CO molecules are incorporated in the inner pores of amorphous solid water and then cover the outermost surface facing to the vacuum, which is followed by the 3D-island growth on it. A similar result is obtained for the adsorption of the CO2 molecule but the filling of the inner pores is not complete due to the lower mobility of the CO2 molecule. The D2O film grows on the CO2 layer, but a pure D2O film is hardly formed on the CO layer due to the occurrence of intermixing. 相似文献
10.
As more efficient and reliable torches for thermal plasma generation have become available in recent years, the use of thermal plasma as an energy source for pyrolysis/gasification has attracted much interest, and special attention has been paid to waste treatment for resource and energy recovery. Plasma pyrolysis/gasification systems have unique features such as the extremely high reaction temperature and ultra-fast reaction velocity compared to traditional pyrolysis/gasification systems. Plasma pyrolysis/gasification is therefore acknowledged as a novel pyrolysis/gasification technology with great potential in solid waste disposal. This paper gives a comprehensive review on the development of fundamental researches on plasma pyrolysis/gasification systems including direct current (DC) arc plasma system and radio frequency (RF) plasma system with an emphasis on reactor design such as plasma fixed/moving bed reactor system, plasma entrained-flow bed reactor system and plasma spout-fluid bed reactor system. 相似文献
11.
电催化CO2还原反应可以产生HCOOH和CO,目前该反应是将可再生电力转化为化学能存储在燃料中的最有前景的方法之一. SnO2作为将CO2转换为HCOOH和CO的良好催化剂,其反应发生的晶面可以是不同的. 其中(110)面的SnO2非常稳定,易于合成. 通过改变SnO2(110)的Sn:O原子比例,得到了两种典型的SnO2薄膜:完全氧化型(符合化学计量)和部分还原型. 本文研究了不同金属(Fe、Co、Ni、Cu、Ru、Rh、Pd、Ag、Os、Ir、Pt和Au)掺杂的SnO2(110),发现在CO2还原反应中这些材料的催化活性和选择性是不同的. 所有这些变化都可以通过调控(110)表面中Sn:O原子的比例来控制. 结果表明,化学计量型和部分还原型Cu/Ag掺杂的SnO2(110)对CO2还原反应具有不同的选择性. 具体而言,化学计量型的Cu/Ag掺杂的SnO2(110)倾向于产生CO(g),而部分还原型的表面倾向于产生HCOOH(g). 此外,本文还考虑了CO2还原的竞争析氢反应. 其中Ru、Rh、Pd、Os、Ir和Pt掺杂的SnO2(110)催化剂对析氢反应具有较高的活性,其他催化剂对CO2还原反应具有良好的催化作用. 相似文献
12.
A. Lucchesini S. Gozzini 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,103(1):74-82
Absorption lines of 12C16O2 have been examined by using a tunable diode laser spectrometer in the region around (790 nm). The spectrometer sources are commercially available double heterostructure InGaAlAs tunable diode lasers (TDLs) operating in the “free-running” mode, which allowed the detection of the line positions within . The observed carbon dioxide absorption lines belong to the combination overtone 2ν2+5ν3 ro-vibrational band with intensities ranging around . 相似文献
13.
Line positions and strengths of 12C16O2 were measured between 4550 and 7000 cm−1 using near infrared absorption spectra recorded at 0.01-0.013 cm−1 resolution with the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory at Kitt Peak, Arizona. These were retrieved from 42 laboratory spectra obtained at room temperature with five absorption cells having various optical path lengths (from 0.1 to 409 m) filled with natural and enriched samples of CO2 at pressures ranging from 2 to 581 Torr. In all, band strengths and Herman-Wallis-like F-factor coefficients were determined for 58 vibration-rotation bands from the least-squares fits of over 2100 unblended line strengths; strengths of 34 of these bands had not been previously reported. Band strengths in natural abundance generally ranged from 3.30 × 10−20 to 2.8 × 10−25 cm−1/molecule cm−2 at 296 K. It was found that the high J transitions (J′ ? 61) of the 20012 ← 00001 band centered at 4977.8347 cm−1 are perturbed, affecting both measured positions and strengths. Two other interacting bands, 21113e ← 01101e and 40002e ← 01101e, were also analyzed using degenerate perturbation theory. Comparisons with corresponding values from the literature indicate that absolute accuracies better than 1% and precisions of 0.5% were achieved for the strongest bands. 相似文献
14.
A. Lucchesini S. Gozzini 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,96(2):289-299
Overtone absorption lines of 12C16O2 have been examined by using a tunable diode laser (TDL) spectrometer in the region around . The spectrometer sources are commercially available double heterostructure InGaAlAs TDLs operating in the “free-running” mode, which allowed the detection of the line positions within . The observed carbon dioxide absorption lines belong to the ν1+5ν3 ro-vibrational band with rotational quantum number J up to 48. The minimum absorbance detected by the spectrometer (?5×10-6) permitted to observe the weakest lines having the absorption cross section of the order of . 相似文献
15.
A.-M Vasserot B Gauthier-Roy H Chabbi L Abouaf-Marguin 《Journal of Molecular Spectroscopy》2003,220(2):201-208
Low temperature (5 K) high resolution (0.15 and 0.03 cm−1) absorption spectra of 13CO2 have been recorded in neon, argon, krypton, and xenon matrices, in the ν3 and ν2 regions. Diffusion experiments have been performed in krypton and xenon in order to identify vibrational traps which could be responsible for the decrease and shortening of the emission observed after laser excitation: high-frequency structures in the ν3 region are assigned to dimers and a doubling of the monomer line is due to a site effect. In neon, only a double substitutional site, with a splitting of the degenerate ν2 vibration, is observed. In argon, as previously reported, a single and a double site are characterized. In krypton and xenon, where ν2 is not split, only single sites would be predicted. As one of them exhibits a ν3 line highly sensitive to temperature, we expect a large coupling with the lattice and a fast vibrational relaxation. This site is very likely the vibrational trap we are looking for. 相似文献
16.
利用脉冲激光溅射-超声分子束载带方法制备了气相Ti+(CO2)2Ar和Ti+(CO2)n(n=3-7)络合物离子.采用红外光解离光谱研究了这些选定的质量离子的振动光谱. 对于每一种络合物离子, 在CO伸缩振动频率范围都观察到了振动峰,表明这些离子具有插入的OTi+CO(CO2)n-1结构. 对于n≦5的OTi+CO(CO2)n-1离子,其CO振动和CO2的反对称伸缩振动频率都比自由的CO和CO2的频率要高,表明CO和CO2配体与中心金属离子之间主要是静电相互作用.实验结果还表明TiO+可以直接络合五个配体(1个CO和4个CO2分子).对于n=2络合物体系,除了插入的OTi+CO(CO2)结构以外,还观察到了具有弯曲结构的OCO-Ti+-OCO异构体的存在 相似文献
17.
Le Kuai Vijay Natraj Charles Miller 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(9):1296-1304
A major challenge in retrieving CO2 concentrations from thermal infrared remote sensing comes from the fact that measurements in the 4.3 and 15 μm absorption bands (AIRS or TES) are sensitive to both temperature and CO2 variations. This complicates the selection of absorption channels with maximum CO2 concentration information content. In contrast, retrievals using near infrared (NIR) CO2 absorption bands are relatively insensitive to temperature and are most sensitive to changes of CO2 near the surface, where the sources and sinks are located. The Orbiting Carbon Observatory (OCO) was built to measure reflected sunlight in three NIR spectral regions (the 0.76 μm O2 A-band and two CO2 bands at 1.61 and 2.06 μm). In an effort to significantly increase the speed of accurate CO2 retrieval algorithms for OCO, we performed an information content analysis to identify the 20 best channels from each CO2 spectral region to use in OCO retrievals. Retrievals using these 40 channels provide as much as 75% of the total CO2 information content compared to retrievals using all 1016 channels in each spectral region. The CO2 retrievals using our selected channels have a precision better than 0.1 ppm. This technique can be applied to the retrieval of other geophysical variables (e.g., temperature or CH4), or modified for other instruments, such as AIRS or TES. 相似文献
18.
Adsorption of pure CO2 on SBA-15 impregnated with branched polyethyleneimine (PEI) has been studied. Materials were prepared by impregnating the pore surface of SBA-15 mesoporous silica with different amounts of branched PEI (10, 30, 50 and 70 wt%). Textural properties, elemental analysis and low angle XRD measurements of the prepared samples showed a progressive pore filling of SBA-15 as PEI loading was increased. Pure CO2 adsorption isotherms on these modified SBA-15 materials were obtained at 45 °C, showing high adsorption efficiency for CO2 removal at 1 bar. Chemisorption of CO2 on amino sites of the modified SBA-15 seems to be the main adsorption mechanism. PEI content of impregnated SBA-15 influences the adsorption capacity of the material, being a relevant variable for CO2 removal by adsorption. Temperature effect on adsorption was also studied in the range 25-75 °C, showing that temperature strongly influences CO2 adsorption capacity. Adsorption capacity was also tested after regeneration of the PEI-impregnated SBA-15 materials. Our results show that these branched PEI-impregnated materials are very efficient even at low pressure and after several adsorption-regeneration cycles. 相似文献
19.
The CO2-broadened water coefficients (half-widths, line shifts, and temperature dependence of the widths) are predicted using a fully complex Robert-Bonamy formulation for the 937 allowed and forbidden perpendicular type transitions of (000)-(000) between 200 and 900 cm−1 in order to facilitate atmospheric remote sensing of Mars and Venus. In addition, empirical Lorentz line widths and pressure-induced frequency-shifts of CO2-broadened H216O are obtained at room temperature for 257 perpendicular transitions of the (010)-(000) fundamental. For this, calibrated spectra recorded at 0.0054 cm−1 resolution are measured assuming Voigt line shapes. For transitions between 1287 and 1988 cm−1 with rotational quanta up to J = 13 and Ka = 6, the widths vary from 0.045 to 0.212 cm−1 atm−1 at 300 K; the pressure-shifts are quite large and range from −0.0386 to +0.0436 cm−1 atm−1. For the (010)-(000) band, the RMS and mean observed and calculated differences for CO2-broadened H2O half-widths are 12% and −1.9%, respectively, while the RMS and mean ratios of the observed and calculated pressure-induced shift coefficients are 1.6 and 0.79, respectively. For pairs of transitions involving Ka = 0 and 1, such as 20 2 ← 31 3 and 31 3 ← 20 2, both the calculated and observed pressure induced shifts in positions are opposite in sign and often similar in magnitude. The data are too limited to characterize vibrational dependencies of the widths, however. 相似文献
20.
The absorption spectrum of the 18O enriched carbon dioxide has been recorded at Doppler limited resolution with a Fourier transform spectrometer in the spectral range 3800-8500 cm−1. Seventeen cold bands (14Σ-Σ and 3Σ-Π) and nine hot bands (9Π-Π) of 12C18O2, nineteen cold bands (18Σ-Σ and 1Σ-Π) and eighteen hot bands (6Σ-Σ, 9Π-Π and 3Δ-Δ) of 16O12C18O have been observed. Among them, 14 12C18O2 bands and 12 16O12C18O bands are observed for the first time. The spectroscopic parameters Gv, Bv, and centrifugal distortion constants, have been determined for all observed bands. Effective Hamiltonian parameters for the 12C18O2 isotopic species are retrieved from the global fitting of the observed line positions presented in this paper and collected from the literature. As the result, 65 obtained effective Hamiltonian parameters reproduce 5443 observed line positions of 73 12C18O2 bands with RMS = 0.00145 cm−1. 相似文献