二氧化碳压缩机组异常情况分析与对策

针对二氧化碳压缩机运行过程中出现的振动和轴温异常的情况进行分析,提出相应的检修处理建议和具体的工艺调整措施。     

CO2气瓶阀的结构与性能分析

阐述了CO2气瓶阀的设计、结构特点、工作原理、发展和分类。     

A high-pressure atomic force microscope for imaging in supercritical carbon dioxide

A high-pressure atomic force microscope (AFM) that enables in situ, atomic scale measurements of topography of solid surfaces in contact with supercritical CO(2) (scCO(2)) fluids has been developed. This apparatus overcomes the pressure limitations of the hydrothermal AFM and is designed to handle pressures up to 100 atm at temperatures up to ～350 K. A standard optically-based cantilever deflection detection system was chosen. When imaging in compressible supercritical fluids such as scCO(2), precise control of pressure and temperature in the fluid cell is the primary technical challenge. Noise levels and imaging resolution depend on minimization of fluid density fluctuations that change the fluid refractive index and hence the laser path. We demonstrate with our apparatus in situ atomic scale imaging of a calcite (CaCO(3)) mineral surface in scCO(2); both single, monatomic steps and dynamic processes occurring on the (1014) surface are presented. This new AFM provides unprecedented in situ access to interfacial phenomena at solid-fluid interfaces under pressure.     

Arc welding of butt joints in carbon dioxide

A method of calculating the welding conditions in carbon dioxide is proposed. Its validity is confirmed by comparing the calculation results and experimental data     

二氧化碳压缩机管线振动原因分析及减振措施

对新疆泽普石化厂二氧化碳压缩机管线振动的原因进行了测试和分析，提出了减振措施，取得了预期效果。     

二氧化碳压缩机振动原因分析及解决措施

河南龙宇煤化工的二氧化碳压缩机采用活塞压缩机,其管道振动十分严重,导致压缩机不能长周期稳定运行。就活塞压缩机管道振动产生的原因及防振措施作了分析,提出防振措施。     

呼气末二氧化碳监测在老年全麻患者中应用价值

目的:探讨呼气末二氧化碳监测在老年全麻患者中的应用。方法:60例拟在全麻下行腹腔镜手术治疗的老年患者随机分为实验组(A)和对照组(B),各30例,行二氧化碳气腹时调整A组患者的呼吸频率和潮气量使呼气末二氧化碳分压(P_(ET)CO_2)在正常范围(35~45mm Hg),B组患者不调整呼吸参数,分析2组患者气腹前5min(T1)、气腹后5min(T2)、10min(T3)、30min(T4),放气后5min(T5)、10min(T6)动脉血二氧化碳分压(PaCO_2)和A组P_(ET)CO_2的变化,并比较2组患者术后苏醒情况。结果:A组通过监测P_(ET)CO_2调整呼吸参数的变化,2组患者T1时点PaCO_2差异无统计学意义,T2~T6时间点A组患者PaCO_2明显低于B组,差异有统计学意义,且A组患者的苏醒时间明显短于B组患者,差异有统计学意义。结论:老年全麻患者使用P_(ET)CO_2监测不仅能够减少CO_2蓄积而且能够提高苏醒质量。     

超临界CO_2萃取胡萝卜中胡萝卜素的研究

本文对胡萝卜中胡萝卜素的超临界CO2提取条件进行研究。分别对不同压力、 温度及夹带剂等几个影响因素进行试验。确定了最佳提取条件为压力5000psi(340大气 压),温度60℃,二氧化碳流量1.5L/min,时间4h。     

Detection of occupancy profile based on carbon dioxide concentration pattern matching

Occupancy is one of major factors influencing indoor microclimate. The aim of this work was to determine the influence of this factor on indoor air quality (IAQ) on the basis of CO₂ concentration measurements and statistical analysis. We wanted to identify periods of time when IAQ was strongly affected by the occupancy described by the given profile. The proposed approach consisted of several stages. The CO₂ concentration was measured and recorded in the form of univariate time series. Then, the relationship between occupancy and internal structure of the time series was disclosed. There were distinguished segments based on sample periodogram. Each segment was associated with a particular occupancy profile. In order to detect how human factor represented by a given occupancy profile influences IAQ we proposed to use pattern matching. In this approach there was examined the similarity between segments of the time series and the pattern of CO₂ variability, which represented a selected occupancy profile. The analysis was performed in time domain using moving time window technique. The similarity was judged based on two types of indexes, namely correlation coefficients and distance measures. It was shown that our approach may be applied to successfully detect a particular occupancy profile. The best performance was achieved when using angular distance as the similarity index. In this case we reached 82% true positive and 22% false positive detections. The proposed method may be applied in diagnostics problems to reveal sources of indoor air quality problems.     

超临界二氧化碳D型管内对流换热研究

D型管换热器应用于快速气冷堆超临界二氧化碳循环中,对超临界二氧化碳在竖直D型管中的对流换热进行了计算研究.分析二氧化碳质量流量、冷却水质量流量以及当量直径等参数对超临界二氧化碳对流换热的影响.结果表明,由于准临界点附近剧烈变物性的影响超临界二氧化碳在D型管内的对流换热非常复杂.对流换热随着温度远离准临界温度,热流密度的增加不断减弱.流量对对流换热的影响比较复杂.在准临界温度附近,浮升力对换热有一定的影响.     

超临界CO2环境下线路板分层机理的模拟与分析

建立线路板试样的有限元模型,利用有限元分析软件ANSYS8.0对超临界CO2环境下的线路板内应力分布及大小进行模拟分析,计算出树脂层的最大剪切应力和最大剥离应力的大小并分析其变化规律,据此推测内应力在线路板分层破坏中的作用及破坏机理,并将分析结果与实验结果对比,以优化回收工艺过程参数.     

基于时序控制算法的二氧化碳洗涤器的研究与应用

针对市场需求,在时序控制算法的基础上,提出了一种活性炭为洗涤媒体的二氧化碳洗涤器的设计原理。以TXF-125型二氧化碳洗涤器为实例,阐述了其系统架构、关键技术。已有公司将该二氧化碳洗涤器批量生产,且产生可观的社会效益和经济效益。     

Turbulent heat transfer of supercritical carbon dioxide in square cross-sectional duct flow

Numerical simulations are performed to develop a new heat transfer coefficient correlation applicable to the gas cooler design of a trans-critical carbon dioxide air-conditioner. Thermodynamic and transport properties of the supercritical gas cooling process change dramatically and significantly vary heat transfer coefficients to be much different from those of single or two phase flows. In the present study, the elliptic blending second moment turbulent closure precisely reflecting the effects of these thermo-physical property variations on the turbulent heat transfer is employed to model the Reynolds stresses and turbulent heat fluxes in the momentum and energy equations. Computational results related to the development of turbulent heat transfer during in-duct cooling of supercritical carbon dioxide were used to establish a new heat transfer coefficient correlation that would be widely applicable to a gas cooler design involving turbulent heat transfer of supercritical carbon dioxide in square cross-sectional duct flows. This paper was recommended for publication in revised form by Associate Editor Kyung-Soo Yang Seong Ho, Han received a B.S. degree in Mechanical Engineering from Kookmin University in 2003. He then went on to receive his M.S. degree from Korea University in 2005. He is currently in a Ph. D. course at Mechanical Engineering at Korea University in Seoul, Korea. His research interests are in the area of hydrogen energy, polymer electrolyte membrane fuel cell.     

氢中微量一氧化碳、甲烷、二氧化碳标准样品的研制及不确定度评定

介绍了氢中一氧化碳、甲烷、二氧化碳标准样品制备过程,建立了标准样品杂质组分的分析方法,对该标准样品性能进行了考察,分析和评定了标准样品的不确定度,通过不同实验室的比对分析说明量值可靠。     

Physical property effects of the compression process with supercritical carbon dioxide as working fluid

Journal of Mechanical Science and Technology - The compressor is one of the key components in the closed supercritical carbon dioxide (S-CO2) Brayton cycle, but its design method is far from...     

The effect of body temperature on the accuracy of arterial and end-tidal carbon dioxide measurement

Measurement of carbon dioxide has great clinical significance during mechanical ventilation, in the adjustment of ventilatory parameters and detection of respiratory complications. The main objective is to investigate the correlation between end-tidal carbon dioxide pressure (PetCO₂) and partial pressure of arterial carbon dioxide (PaCO₂) measured at 37 °C and corrected for body temperature in patients with thermal instability. Altogether, 110 measurements were analyzed, and the correlation was statistically more significant for corrected temperature than measured PaCO₂. The difference between corrected and uncorrected PaCO₂ varies from 3% per °C for hypothermic patients and 6.5% per °C for hiperthermic patients. The difference between PaCO₂ measured and PetCO₂ (Pa-etCO₂) resulted in an increase for all temperature degree, reaching a maximum difference of 9 torr. In contrast, Pa-etCO₂ has little variation when corrected PaCO₂ was used for calculation around −2.1 to 3.1 torr for hypo and hiperthermic patients. Thus, PetCO₂ reflects temperature corrected PaCO₂ more adequately than measured PaCO₂.     

正交试验优选半枝莲超临界二氧化碳萃取条件及GC/MS分析

本文采用正交设计法,对半枝莲挥发油超临界CO2流体提取工艺参数进行优化,并对萃取产物的化学成分进行GC/MS分析。正交实验设计萃取压力（A）、萃取温度（B）、药材粒度（C）作为3个因素,每个因素选3个水平,以挥发油的得率来确定最优化提取条件。用GC-MS分析技术对半枝莲超临界萃取产物进行分离分析,采用MS谱库检索结合保留指数的方法对半枝莲超临界萃取成分进行结构鉴定,应用色谱峰面积归一化法确定萃取产物中各成分的峰面积百分含量。结果表明最优萃取条件：萃取压力30Mpa,萃取温度50℃,药材粒度40~60目。萃取产物GC-MS结果显示,半枝莲中除含高级脂肪酸及其酯类外,还含有大量的甾族化合物。本研究优化的萃取工艺稳定、可行;利用GC/MS分析技术,MS谱库检索结合保留指数鉴定结构的方法准确、快速。     

Phase separation in alcohol/liquid carbon dioxide solvent systems facilitates critical point drying

Carbon dioxide and methanol or ethanol, although miscible, form alcohol/CO₂ solutions that do not easily mix with additional pure liquid CO₂. If the CO₂ inlet is situated at the top of a critical point drying apparatus chamber, pure CO₂ will entirely displace the alcohol/CO₂ phase (which is more dense) while keeping the chamber filled with liquid. This unexpected phenomenon is invaluable in critical point drying delicate biological tissues which remain continuously immersed, avoiding surface or convection currents. By providing an objective criterion for intermediate solvent displacement, the protocol also eliminates ambiguous ‘flushing’ steps.     

A multi-factor comprehensive optimization of a supercritical carbon dioxide radial inflow turbine with low specific speed

Journal of Mechanical Science and Technology - An integrated method combining one-dimensional design and automatic three-dimensional optimization is proposed for SCO2 radial inflow turbines with...     

The fretting wear of an austenitic stainless steel in air and in carbon dioxide at elevated temperatures

The development of an experimental test facility designed to investigate the fretting wear of metals in high temperature gaseous atmospheres is described briefly. Small amplitude torsional fretting was produced between normally loaded annular contact surfaces at temperatures up to 650 °C. The information presented concerns the effects produced on fretting a type 321 stainless steel in air and CO₂ environments. Use of electron optical and surface profiling techniques has allowed a qualitative asessment of the degree and characteristic features of the damage to specimens fretted at room temperature and 650 °C under selected oscillatory wear conditions. During simultaneous oxidation and fretting at 650 °C the initially formed protective oxide is disrupted exposing a chromium-depleted surface which subsequently oxidizes to a less protective Fe-Cr spinel. This combination of effects could have unfortunate consequences on the long term wear behaviour.