关于CJ/T 197-2010《燃气用具连接用不锈钢波纹软管》标准中螺纹要求的解析

针对CJ/T 197-2010《燃气用具连接用不锈钢波纹软管》标准中GB/T 7306. 1-2000和GB/T 7306. 2-2000与GB/T 7307-2001管螺纹标准之间异同点进行辩析,为使用者提供参考。针对燃气用具连接用不锈钢波纹软管对螺纹要求,及其与螺纹标准的对应关系进行解析,提出标准中存在的问题,及燃气用具连接用不锈钢波纹软管标准关于螺纹要求修改的意见和建议,完善燃气用具连接用不锈钢波纹软管标准,利于燃气用具连接用不锈钢波纹软管标准的推广使用。     

标准煤气表仪表系数测量不确定度分析

本文简略介绍了标准煤气表的测量方法，并依据JJG267-1996标准煤气表检定规程和JJF1059-1999测量不确定度评定与表示，对标准煤气表仪表系数测量结果进行不确定度的评定。具体分述各个不确定度分量（包括标准煤气表示值、气体流量标准装置通过的气体体积、装置内压力、标准煤气表前压力、装置内气温、标准煤气表前气温、装置内的饱和蒸汽压、标准煤气有处的饱和蒸汽压、装置内气体相对湿度、标准煤气表处的气体相对湿度）的产生，并合成标准不确定度及给出有效自由度。     

Detection of Moisture and Methanol Gas Using a Single Electrospun Tin Oxide Nanofiber

This letter reports the fabrication of a gas sensor based on a single tin oxide nanofiber made from dimethyldineodecanoate tin using electrospinning and metallorganics decomposition techniques. The fabricated sensor has been used to detect moisture and methanol gas. It showed high sensitivity to both gases and the response times of the complete testing system are in the range of 108-150 s for moisture, and 10-38 s for methanol gas, respectively.     

Thermal accommodation coefficient of gases on controlled solid surfaces: Argon-tungsten system

The knowledge of the thermal accommodation coefficient for gases on well-controlled surfaces as a function of temperature is imperative to understanding the mechanism of interphase heat transfer on the microscopic level. With this goal in view, a heat transfer column instrument is designed, fabricated, assembled, and tested for the specific case a argon—tungsten system. With 99.9999%, pure argon, six sets of data are taken in the rarefied gas region in the maximum temperature range of 500–1500 K. Four sets of these measurements are in the temperature-jump region and are analyzed by the constant-power method to compute the thermal accommodation coefficient of argon on a controlled tungsten surface. The other two sets are taken under free-molecular flow conditions and are interpreted in accordance with the man-free-path kinetic theory for the low-pressure regime. These data are compared and discussed in the context of reported data in the literature and interpreted in the light of the surface condition and finish of the tungsten wire.Nomenclature A area of the solid surface - C _j constants in Eq. (3); j=0, 1, 2, 3, and 4 - E _i incident energy flux - E _r reflected energy flux - E _s reflected energy flux when the interaction between the gas and the solid atoms is complete - g temperature-jump distance - L half-length of the metal wire - M molecular weight of the gas - P gas pressure - Q _H total thermal energy conducted by the gas per unit time from the hot surface - Q_KT total thermal energy conducted by the gas per unit time if the striking gas molecules were to attain thermal equilibrium with the hot surface - R molar gas constant - r radial coordinate - r _f radius of the hot wire - S sticking coefficient - S_o initial sticking coefficient - T temperature - T _e linearly extrapolated gas temperature on the hot-wire surface - T _g temperature of the impinging gas molecules - T _H temperature of the hot surface - T _i temperature of the incident gas stream - T _r temperature of the gas molecules receding after collision with the solid surface - T _s temperature of the solid surface Greek Symbols thermal accommodation coefficient for the gas—solid surface - resistivity of the metal wire - gas coverage on the solid surface For an explanation of symbols, see Nomenclature.     

环境监测用空气中二氧化碳标准气体的研制

介绍了环境监测用空气中二氧化碳标准气体的制备方法。该标准气体的均匀性和稳定性通过气相色谱法进行了考察,并用比对误差确认了其称量法配制值的准确性。配制的标准气体的浓度为（10～1000）×10^-6（mol／mol）,定值不确定度小于2％。     

Working standard of the unit of gas flow in a vacuum VÉT 49-2-2006

The working standard for the unit of gas flow in a vacuum VéT 49-2-2006 is described. The composition of the standard and metrological characteristics are provided. A local verification scheme is given for the measurement provisions of gas flow in a vacuum. __________ Translated From Izmeritel’naya Tekhnika, No. 3. pp. 45–48, March, 2007.     

Change in the hydrophysical and hydrochemical characteristics of natural waters with magnetohydrodynamic activation

It is shown that the effects which arise in natural waters when they flow through nonuniform magnetic fields are governed by an increase in the free gas concentration and hydrodynamic characteristics of these waters.Notation c_fr.g concentration of free gas in the liquid (in micro- and macrobubbles) - c_r.g concentration of molecular-dissolved gas - Re Reynolds number - p_atm atmospheric pressure - W amount of gas removed from the liquid by evacuation - n multiplication factor of evacuation - V liquid flow velocity, m/sec Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 1, pp. 64–69, July, 1980.     

中空纤维膜氢回收系统在制氢装置的应用

简述了中空纤维膜分离原理、开车步骤，分析了中空纤维膜氢回收系统标定数据，指出存在的问题，并进一步对比分析了加氢干气直接作为制氢原料和用中空纤维膜氢回收系统的非渗透气作为制氢原料的优缺点．     

双头涡旋齿涡旋压缩机气体力分析

详细分析了整数圈数双头涡旋齿涡旋盘所受的切向力气体力、法向气体力、轴向气体力,提出了在任意曲轴转角下的各种气体力及各个工作腔容积的计算公式。通过对相同排气量的单、双头涡旋齿涡旋盘气体力比较得出：双头涡旋齿涡旋盘所产生的气体力大,是单头涡旋齿涡旋盘所受气体力的1．1—1．5倍;双头涡旋齿涡旋盘所受气体力的波动小,是单头涡旋齿涡旋盘气体力的波动的1/3-1/5。所以双头涡旋齿结构更适合排气量大的场合。通过分析整数圈数及非整数圈数的双头涡旋齿涡旋盘的几何关系,提出了非整数圈数双头涡旋齿涡旋盘的气体力模型。研究结果可在双头涡旋齿涡旋压缩机的设计和研究中直接应用。     

Radon exposures from the use of natural gas in buildings

Low levels of natural radioactivity in the ground produce radon-222 and its decay products which can be entrained with gas streams and become distributed with gas supplies to commercial and domestic users. Levels of radon in blended gas received by most users are comparable with the levels that are present naturally in buildings as a result of ingress from the ground and this is further diluted during the combustion process. For typical rates of gas usage with an average radon level of about 200 Bq x m(-3), the estimated dose from the use of natural gas is estimated at 4 microSv, less than 1% of the dose from radon exposure at the average level in UK homes. Commercial users may receive somewhat higher doses, and the estimate for a critical group is a few tens of microsievert. The total radon emission to the environment is estimated at about 10(13) Bq x y(-1) which represents less than 10(-4) of the natural emission rate from the ground. There is some variability of radon levels in gas from different sources and it would be prudent to keep this source of exposure under review. A standard sampling and measurement protocol has been developed in conjunction with a technical group representing the industry.     

螺旋槽干气密封气膜刚度测试与稳定性分析

干气密封的关键技术是动压效应和稳定性问题,而气膜刚度是影响振动稳定性的主要参数之一。采用高精度改进型的电涡流微型传感器和Labview软件,并采用一系列的抗干扰措施,建立了螺旋槽干气密封的测试系统。通过测量干气密封的轴向静环振幅和轴向气膜振幅,而获得气膜刚度,并分析了其气膜振动的稳定性。试验研究表明：随着转速的增加和压力的升高,气膜刚度随之增大,气膜稳定性越好。本例中：压力变化范围为0.2-0.5MPa,转速变化范围为500 - 3000 r/min,得气膜刚度值的变化范围为0.01 - 0.03 KN/μm,且气膜刚度分别与压力和转速基本成线性关系;试验中测试了三种不同螺旋角的样机,得螺旋角为74°时,气膜刚度最大,气膜稳定性最好,选取合适的螺旋角可增加气膜的稳定性,从而对结构参数的优化提供了指导。     

氧化锡纳米线的制备及其乙醇气体敏感性能

采用热蒸发法成功制备氧化锡纳米线。用X射线衍射、扫描电子显微镜和透射电子显微镜对所制备纳米线的晶格结构和表面形貌进行表征。所制材料为金红石氧化锡单晶结构,纳米线直径为50~200nm,长度为5~15μm,符合气-液-固生长机制。以氧化锡为气敏材料,制备了旁热式结构气敏元件,测试该元件对浓度范围为25×10^-6 ~500×10^-6 的乙醇气体环境的敏感性能。结果表明,该元件的最佳工作温度约为260℃;在25×10^-6 和500×10^-6 的乙醇气体中,灵敏度分别为7.54和111.01,响应时间为2~20s,恢复时间为5~33s;在测试范围内灵敏度与气体浓度具有良好的线性关系;7天内重复测量误差在5%以内,稳定性较好。     

Development of a pulsed backscatter-absorption gas-imaging system and its application to the visualization of natural gas leaks

The design and evaluation of a backscatter-absorption gas-imaging sensor that operates in a pulsed mode is described. It is capable of video visualization of natural gas leaks. Its development was motivated by the need for a methane imaging system to operate at ranges and sensitivities useful to the natural gas industry. The imager employs pulsed laser illumination at a repetition rate of 30 Hz and an average power of ~150 mW to image gas at standoff ranges of as long as 100 m, using a backscatter target with a reflectivity of 0.016 sr(-1). This is a tenfold improvement over an earlier raster-scanned imager. Natural gas leaks as small as 1.6 x 10(-4) standard liters/s [equal to 0.02 standard cubic feet per hour (scfh)] were imaged at short ranges; leaks as low as 7.9 x 10(-4) standard liters/s (0.1 scfh) were observed at long ranges. Data are compared with model predictions, and potential extensions to a fieldable prototype are discussed. The optimization of a direct-injection focal-plane array for detecting short (nanosecond) laser pulses is described.     

On the optimal temperature profile of selective gases under radiant heat transfer

It is shown that a selective gas temperature profile exists for which radiant heat flux is a maximum in the heating surface. The mean, minimum, and maximum gas temperatures are determined.Notation q resultant radiant heat flux at the heating surface - Q₁, Q₂ flux of intrinsic gas radiation on the heating surface and the lining, respectively - r reflexivity of the heating surface - Q₀₁, Q₀₂ intrinsic radiation fluxes of the heating surface and the lining - layer thickness - D₁, D₂, D₃ transmissivity of the gas layer for radiation of the heating surface, lining, and layer of the same gas - E₃ integral exponential function of third order - ¯T mean gas temperature - T₁ heating surface temperature - T_m maximum temperature - StefanBoltzmann constant - y coordinate of the layer measured from the lining Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 1, pp. 109–112, July, 1980.     

Relationship between dynamic characteristics of air film of aerostatic spindle and mid-frequency of surface topography

The dynamic characteristics of the gas film of an aerostatic spindle primary affect workpiece waviness in ultra-precision machining. To improve the machining accuracy of the machine tool and provide a firm theoretical basis for the design of an aerostatic spindle, a simulation model combining transient computational fluid dynamics (CFD) analysis and transient dynamic analysis is established in this study to investigate the dynamic characteristics of the spindle under unstable operating conditions. Based on a large eddy simulation, a three-dimensional flow model of an air film in an aerostatic spindle is established. The simulation results show that the gas flow in the throttle chamber is turbulent, and that complex vortices are formed. Using dynamic grid modeling technology, a CFD numerical model for the unsteady calculation of the spindle is established, and the dynamic characteristics of the gas film are obtained. A transient dynamic simulation model of an aerostatic spindle is established, and the effect of the nonlinear dynamic characteristics of the gas film on the spindle displacement response is investigated. Subsequently, a surface morphology prediction model is established. Results show that film fluctuation significantly affects the dynamic characteristics of the spindle and subsequently affects the generation of surface ripples on the workpiece.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00391-4     

Collision cross section of fast beam by neutral gas target

Effective deexcitation cross sections of fast beams of Na, Ne, and Li+ in the excited P state at energies of -160 keV with a N2 gas target are reported. These cross sections are obtained from analysis of the dependence of the effective lifetime on the gas pressure. Results for neon indicate small variations of deexcitation cross section for the different 3p fine structure levels.     

Synthesis of nestlike ZnO hierarchically porous structures and analysis of their gas sensing properties

Nestlike 3D ZnO porous structures with size of 1.0-3.0 μm have been synthesized through annealing the zinc hydroxide carbonate precursor, which was obtained by a one-pot hydrothermal process with the assistance of glycine, Na(2)SO(4), and polyvinyl pyrrolidone (PVP). The nestlike 3D ZnO structures are built of 2D nanoflakes with the thickness of ca. 20 nm, which exhibit the nanoporous wormhole-like characteristic. The measured surface area is 36.4 m(2)g(-1) and the pore size is ca. 3-40 nm. The unique nestlike 3D ZnO porous structures provided large contacting surface area for electrons, oxygen and target gas molecules, and abundant channels for gas diffusion and mass transport. Gas sensing tests showed that the nestlike 3D ZnO porous structures exhibit excellent gas sensing performances such as high sensitivity and fast response and recovery speed, suggesting the potential applications as advanced gas sensing materials.     

Determination of methane in ambient air by multiplex gas chromatography

A multiplex gas chromatographic technique for the determination of methane in ambient air over extended periods is reported. A modest gas chromatograph which uses air as the carrier gas was modified by adding a silver oxide sample modulator for multiplex operation. The modulator selectively catalyzes the decomposition of methane in air. The resulting analytical systems requires no consumables beyond power. A profile of the methane concentration in this laboratory was obtained for an 8-day period. During this period, methane concentration varied with an approximately daily period from a low of 1.53 +/- 0.60 ppm to a high of 4.63 +/- 0.59 ppm over the entire 8 days. Some of the measured concentrations are higher than those reported elsewhere indicating the presence of some local source or sources for methane. This work has demonstrated the utility of a relatively simple multiplex gas chromatograph for the analysis of environmental samples. The technique should be applicable to other trace components in air through use of other selective modulators.     

Dry scrubbing of acid gases in recirculating cyclones

This paper describes a laboratory-scale study on the use of recirculating cyclones as reaction chambers for dry scrubbing of gaseous HCl with solid slaked lime particles. This gas cleaning system combines a numerically optimized reverse flow gas cyclone (RS_VHE geometry) with a straight-through cyclone concentrator, which simultaneously increases the capture of the solid particles and promotes their partial recirculation. A laboratory-scale study was undertaken to test this technology and to compare its performance to a modified Stairmand HE reverse flow cyclone without recirculation. The experimental conditions were: reaction temperature approximately 326 K, gas flow rate approximately 2.9 x 10(-4) Nm(3) s(-1) and relative humidity of the gas approximately 8.5%. The experimental variables tested were the solids load (1.0-9.2 x 10(-7) kg s(-1)) and HCl concentration (0.4-2.8 x 10(-2) mol m(-3)) in the inlet gas. The experimentally obtained particulate removal efficiencies with the recirculating cyclones ( approximately 98%) were higher than those obtained with the Stairmand HE cyclone ( approximately 93%), with the additional advantage of having significantly lower pressure drop. As for the acid removal efficiencies ( approximately 10-96%), no significant differences were found between the two systems tested under the same experimental conditions. The possibility of using optimized recirculating cyclones for gas cleaning in a dry scrubbing process is very promising, since this is a low cost technology, highly efficient both for the removal of acid gases and for the capture of solid particles, which has the advantage of not requiring a post-reaction de-duster.     

Stripping as a pretreatment process of industrial oily wastewater

In the present work, the potential of purifying an oily wastewater from a lubricant production unit, consisting mainly of alcohols, phenols and heavy linear saturated hydrocarbons, using the stripping process was examined. The effect of stripping gas flow (75-300 L(N2) L(WW)(-1) h(-1)) and system temperature (295-355 K) on the chemical oxygen demand (COD) of the effluent was investigated. A decrease in COD content of 25-30% was achieved after 4 h for stripping gas flow rates over 150 L(N2)L(WW)(-1) h(-1), whereas the rate of organic compounds removal was enhanced by increasing temperature up to 333 K. At higher temperatures an effluent condensation was observed. Gas chromatography-mass spectrometry analysis of both liquid and gas phase showed that linear saturated hydrocarbons of high molecular weight were stripped out from the wastewater. The results are in agreement with the equilibrium ratio of these compounds as predicted from by theoretical calculations.