H2O Gas Mixture Research Articles

Sound absorption in N2−H2O gas mixtures at elevated temperatures

Sound absorption measurements were conducted in N2−H2O gas mixtures at 297°, 343°, and 387°K to determine the location of the vibrational relaxation peak of N2 on the frequency/pressure (f/P) axis as a function of humidity and temperature. At low humidities, the best fit of the reported data to a linear relationship between (f/P)max and humidity h yields, within experimental error, the same slope (2.00 × 104 Hz/atm mole fraction) at all three temperatures. The slope is lower than the value of 2.6 × 104 reported by Chang, Shields, and Bass at higher humidities [J. Acoust. Soc. Am. 63, 577–581 (1977)], but the two sets of data are shown to be mutually consistent by means of a model in which V-V transfer is assumed to provide the dominant relaxation path. The relationship between (f/P)max and h written into ANSI Standard S1.26/ASA23-1978 contains an excessively large slope, does not account for the observed transition between the low-humidity and high-humidity slopes, and specifies an erroneous temperature dependence. [Work supported by NASA Grant NSG 1324.]

Effect of Residual CO on Combustion-Type CO2-Gas Dynamic Laser Performance

The CO2-Gas Dynamic Laser (GDL) has been developed as a high-power laser. The combustion-type CO2-GDL has the particular merit of a readily obtainable high input energy, because it can use chemical reaction energy. In this type of GDL, however, impurities such as CO and O2 which result from imperfect combustion are present in the laser medium. This paper presents experimental studies of the influence of these impurities on CO2-GDL performance. CO and CH4 fuel is burned with air and N2 is added to form high temperature (1500 K) CO2–N2–H2O gas mixtures. All the observed impurities were CO and O2. Both gain and power decreased monotonically with the increase of CO mole fraction up to 10%. The mole fraction of O2 was always approximately 0.5%, and higher levels of O2 fraction led to unstable combustion.

A One-Dimensional Model Describing Aerosol Formation and Evolution in the Stratosphere: I. Physical Processes and Mathematical Analogs

Abstract We have developed a time-dependent one-dimensional model of the stratospheric sulfate aerosol layer. In constructing the model, we have incorporated a wide range of basic physical and chemical processes in order to avoid predetermining or biasing the model predictions. The simulation, which extends from the surface to an altitude of 58 km, includes the troposphere as a source of gases and condensation nuclei and as a sink for aerosol droplets; however, tropospheric aerosol physics and chemistry are not fully analyzed in the present model. The size distribution of aerosol particles is resolved into 25 discrete size categories covering a range of particle radii from 0.01–2.56 µm with particle volume doubling between categories. In the model, sulfur gases reaching the stratosphere are oxidized by a series of photochemical reactions into sulfuric acid vapor. At certain heights this results in a supersaturated H2SO4–H2O gas mixture with the consequent deposition of aqueous sulfuric acid solution on th...

Effect of nonequilibrium processes in the infrasonic and ultrasonic regions of a nozzle on population inversion in flow of CO2 - N - O2 - H2O gas mixtures

The processes of oscillatory relaxation in flow through nozzles of CO2, N2, O2, H2O gas mixtures are studied. The effect of various oscillatory-oscillatory and osciallatory-translational exchange channels between mixture components and CO2 intermode energy-exchange Channels on population inversion is examined. The importance of considering nonequilibrium processes in the infrasonic region of the nozzle is noted. The effect of inclined shock waves on flow characteristics in the supersonic nozzle region and population inversion is studied.

Water Cluster Ions: Formation and Decomposition of Cluster Ions in the Oxygen-Water System

Drift-tube techniques have been employed to determine rate constants in the reaction sequence leading to formation of the hydronium ion hydrates H3O+(H2O)n starting from O2+ ions in O2–H2O gas mixtures at 310°K. Total pressures used ranged from 0.5 to 2 torr with water partial pressures from 0.15 to 1.2%. Measured three-body clustering rate constants declined in all cases as E/P0 increased in the range 5–30 V cm−1· torr−1. Thermal rate constants were deduced from the low E/Po data. Mobilities for O2+ and H3O+(H2O)n in oxygen are given as a function of E/Po in the range 5–60 V cm−1· torr−1 and for O2+ and H3O+ in argon from 4 to 20 V cm−1· torr−1. In oxygen, quasiequilibrium studies were conducted in which a cluster ion H3O+(H2O)n loses one or more water molecules during drift, successive ions from n=3 to 0 becoming dominant as E/Po increased from 5 to 60 V cm−1· torr−1. A simple analytical model for treating sequential reactions in drift experiments is presented.

Ion–Molecule Reactions in NO–NH3 Gas Mixtures

Stationary afterglow techniques have been employed to produce and observe ions reacting in NO–NH3 gas mixtures. The precursor ion, NO+, is found to cluster with NH3 and then reacts further to yield NH4+. Arguments are presented for the formation of ONNH2 as a byproduct of the latter reaction. The NH4+ ion undergoes successive clustering with NH3 to produce NH4+·nNH3, n = 1, 2, 3. The NH3 clustering reactions are similar to those observed for H2O in NO–H2O and O2–H2O gas mixtures. Rate constants for all forward and all observed reverse reactions have been measured at 296°K.

Production of H3O+·nH2O from NO+ Precursor in NO–H2O Gas Mixtures

Stationary afterglow techniques have been employed to determine reaction rate constants for ions reacting in NO–H2O gas mixtures. Krypton resonance radiation at 123.6 and 116.5 nm is used to ionize only the NO molecules. The NO+ ion is the precursor to a chain of reactions which result in NO+·nNO(n = 1,2), NO+·nH2O(n = 1,2,3), and H3O+·nH2O(n = 2,3,4) being formed. Rate constants and/or equilibrium constants are provided for all forward and all reverse reactions at 296°K.

High-Temperature Spectral Emissivities of H_2O–CO_2 Mixtures in the 27-μ Region

Spectral emissivities in the 2.7-μ band were obtained for hot gas mixtures of CO2 and H2O between 1000°K and 2200°K for various (CO2/H2O) sample ratios. The emission measurements were made at the exit of a small tripropellant rocket burner which produced the variable (CO2/H2O) mixtures by burning hydrogen, oxygen, and carbon monoxide. The spectral emissivities were determined from a calibrated emission spectrum and a spectroscopic determination of the temperature of the hot gas. The composition was evaluated from a semiempirical fit to a thermochemical flow calculation. The hot CO2–H2O mixtures were observed at a total pressure of 1 atm in the optically thin absorption region with a constant geometric pathlength. The variations of the spectral emissivities as a function of temperature are given for constant density of CO2 and H2O in the optical path. The experimental results agree with semitheoretically derived predictions. The characteristic area ratios of the integrated emissivities or integrated radiances within portions of the 2.7-μ band were derived and given as a function of temperature and (CO2/H2O) sample ratio. These area ratios can be used to determine the (CO2/H2O) concentration in hot gas samples.

The Equilibrium between the Sn-Pb Liquid Solution and the H2–H2O Gaseous Mixture

Abstract Equilibrium in Sn (in liquid alloy)-H2O–SnO2–H2 system has been determined from 750 to 800°C by measuring the ratio of pressures between H2O and H2 gas mixtures. From this the activity of tin liquid tin-lead solutions has been calculated, and the following equation has been derived at 775 °C. \barGSne=2330(1−xSn)2−600(1−xSn)3 cal./mol. The temperature dependence of \barGSne could not be determined. However, if this value is calculated by combining Kleppa’s value for the excess heat, calorimetrically determined, with that of Elliott and Chipman for the excess entropy, the agreement between the value thus obtained and that of the present investigation is quite reasoable, taking into consideration the accuracies of these experiments. Theoretical considerations have been given for the excess functions of this system. It shonld be emphasized that the electrochemical effect of charge transfer is very small or may be regarded as zero in the lead-tin system and that the size factor is important.

製鋼の基礎反応に関する統計熱力学的研究（第1報）熔鉄と混合気体H2O, H2及びCO, CO2との平衡関係式の理論的導出

Stoichiometric chemical equations have been used to show the equilibrium relation between gas phases and liquid or solid phases in the field of chemical metallurgy, or of especially the physico-chemical studies of fundamental reactions concerning steel-making. But in those procedures the equations means are physically ambiguous, so that the equilibrium constants, namely, the relations between partial pressures of gas phases and concentrations of solute molecules in molten or solid phses, founded on such equations are only satisfied approximately in the case of very low concentration or in the case of energies of mutual interaction between solute atoms being very small as compared with kT. Therefore, we must avoid the use of the stoichiometric chemical equations in treating these problems. Free energies of gas phases and condensed phases dissolving the gas atoms were calculated on the basis of statistical mechanics, and theoretical formulas were obtained to show the relations between the partial pressures of gas phases, concentrations of dissolved atoms and temperature from the general principle that the chemical equilibrium between gas phases and condensed phases are satisfied when the total sum of their free energies has a minimun value.In this paper, as an example, the following problems were treated accorbing to the method described above, [i)] chemical equilibrium between the molten iron and gas-mixtures of H2 and H2O [ii)] equilibrium relations between the molten iron and gas-mixtures of CO2 and CO.