脉管制冷机污染试验研究

通过强化加速试验,从运行时间、加热烘烤温度、自由气体污染和约束气体污染等方面研究了工质气体污染对脉管制冷机制冷性能的影响,试验结果表明,脉管制冷机在工作时,污染物在回热器内的重新分布以及污染回热材料是脉管制冷机产生污染效应的主要因素。结合传热及流阻等理论对试验结果进行了机理分析,其试验结论有助于脉管制冷机的空间工程化应用。     

牛津型斯特林制冷机的加速寿命试验

分析了牛津型长寿命斯特林制冷机的主要失效模式、失效机理以及应用特点,提出高温运行的加速寿命评价方法.4 300 h的加速寿命试验结果表明,制冷机性能已明显退化,并呈现污染导致的失效特征,初步验证高温加速污染失效的有效性.     

斯特林制冷机污染失效研究进展

斯特林制冷机内部放气造成的失效严重影响制冷机寿命。制冷机内部放气气体会在回热器冷端及膨胀腔低温表面凝结,降低回热器的回热效率和冷头换热面传热能力,并加大制冷工质流动阻力。主要介绍了斯特林制冷机加速寿命试验和污染放气模拟数值计算方法等,提出了制冷机污染失效研究发展方向。对今后主要研究方向进行了展望。     

丙酮污染对微型机械制冷机性能影响的实验研究

设计微型高压阀直接向机械制冷机内在线、连续地添加污染杂质,提出了制冷机丙酮污染的强化加速实验方案,从量化角度深入研究了污染对回热式机械制冷机性能影响的规律.实验分析表明,随着丙酮添加量的增加,制冷能力首先稍微增强,然后在42 mg和121 mg时分别出现了性能衰变的拐点.在间歇性开机时还发现了制冷机污染效应的时延现象.结合传热、流阻等理论对实验规律进行了分析讨论,为机械制冷机的可靠性技术和寿命预测研究奠定了基础.     

斯特林制冷机充气纯化试验装置的研制

斯特林制冷机内工作氮气的污染严重影响制冷机的性能和寿命。详述了研制的制冷机气体充气纯化试验装置的功能、技术特点及试验结果。     

基于烟线技术的脉管制冷机流动可视化实验研究

脉管制冷机在低温部分没有运动部件,具有振动低、寿命长等突出优点,在空间技术、超导磁体冷却等方面应用广泛。但是脉管制冷机工作机理复杂,内部为交变流动,很多参数难以测量。常规方法无法显示实验过程中制冷机内部气体的流动情况,给学生理解脉管制冷机原理和工作特性带来了困难。基于烟线技术的可视化实验,可以直观地反映脉管制冷机内部气体的流场,能够直接观察制冷机运行时内部气体的流动情况。     

深冷文献消息(国内部分)

<正>986101 交变流动气体制冷机的相位控制方法研究陈登科《低温与超导》1998 №3 1~8分析了交变流动气体体制冷机的相位控制机理,归纳总结了已有的相调方案,还提出了一些新的调相方法。在此基础上,形成了交流制冷机调相     

星载斯特林制冷机污染控制工艺研究

污染是影响星载斯特林制冷机寿命的关键因素。为提高制冷机可靠性,必须对污染进行控制。主要介绍了污染对制冷机性能的影响以及污染控制的工艺处理方法。     

扩散——吸收式制冷系统的热力计算

本文对扩散——吸收式制冷系统的工作机理及热力计算进行了探讨。对该系统发生器中热虹吸过程以及吸收器与蒸发器之间的气体循环过程作了热力分析,并提出扩散——吸收式制冷机选定循环参数和热力计算的方法。     

气波制冷机的研究与应用

气波制冷机是利用气体的压力能制冷的一种制冷设备，文中主要介绍了气波制冷机的研究历史、制冷机理及实验研究的国内外现状，阐述了气波制冷机的主要应用领域。     

Contamination control by a greenhouse for emergency medical treatment of the contaminated patient

In emergency medical treatment of patients contaminated with radioactivity, air contamination control is very important to prevent the secondary contamination of medical staff. In order to optimize design of a greenhouse, a numerical analysis was made by using the Flow Designer software. As a scenario of air contamination, the breathing air of the patient was assumed to be highly contaminated with radioactive gaseous or particulate matter. It was found that air contamination strongly depended on the characteristics of the contaminants. The contamination map of the coarse aerosols with low diffusivity was quite different from those of the fine aerosols and gas. If the setting conditions of air-flow rate of the ventilation and the exhausting position were optimized, secondary contamination of the medical staff standing by the patient is prevented securely by a greenhouse.     

Protection of large flammable storage tanks during repair by means of nitrogen-filled high expansion foam

Storage tanks contaminated by flammable residues require protection during repair or demolition. Nitrogen-filled high expansion fire-fighting foam has been proposed for this protection. In this series of tests a 500 tonne aviation fuel storage tank was filled with appropriate foam to observe foam behaviour with particular reference to oxygen contamination in aged foam. For comparison, gas inerting with nitrogen was included in the test series. In one test a hot cutting procedure was monitored for void formation and oxygen contamination of the foam.Oxygen contamination was low in foam up to three hours old. Voids and oxygen introduced by hot cutting were rapidly purged. The use of foam enabled the tank to be rendered inert using less nitrogen than with the gas alone and had the additional advantage that the inerting agent was visible.     

Investigation of Tin films reactively sputtered using a sputter gun

TiN films were prepared by reactive sputtering of titanium in a gas mixture of argon and nitrogen using a sputter gun. The properties of the sputtered films were investigated with Rutherford backscattering spectrometry, electrical resistivity and optical reflectivity measurements, X-ray diffractometry and transmission electron microscopy. For a given input power to the sputter gun the film properties depend on the gas composition, the bias voltage applied to the substrates and oxygen contamination during sputtering. In addition, it was found that powering the sputter gun with r.f. causes an iron contamination in the films by material sputtered off the plasma confinement shield. This contamination is very much reduced when d.c. is employed to power the sputter gun.     

气路切换装置在气体检测中的应用

为了解决气体样品检测分析中遇到诸如气体样品量少、仪器因高压而损坏等问题,该文介绍一种新型的气路切换装置及其工作原理,检测前先使用相对高纯气体吹扫仪器,待仪器稳定后,使用四通阀将样品气体切换至仪器。罗列及比较了不同材料对检测结果的影响,结果表明采用适当的材料、合理的设计、谨慎的操作,可以有效避免外界气体杂质污染。装置实现了快速分析、少量进样,大大提高工作效率,同时可避免不必要的财产损失。     

Structural stability and mechanochemical activity of titanium nitride prepared by mechanical alloying

Pure titanium nitride (TiN) was synthesized by mechanical alloying (MA). In order to prevent the contamination from the MA vial and atmospheric gas, the MA steel vial was replaced with a titanium vial and atmospheric gas was deoxidized using sponge titanium heated to 623 K. The mechanochemical activity during MA was estimated from the gas purification temperature. The investigation of thermal and pressure stability by thermal treatment and hot isostatic pressing (HIP) revealed that titanium nitride, TiN, was stable on heating to 1173 K under a vacuum, but became unstable under a high pressure, 100 MPa.     

Factors affecting the velocity of launching bodies by means of an electric-discharge light-gas accelerator

The effect is investigated of a number of factors, which accompany the operation of an electric-discharge light-gas accelerator, on the velocity of launching bodies. One such factor is the contamination of the working gas with electrode erosion products. It is found that, at a temperature of the working gas of 2500–3000 K and below, the erosion of electrodes and walls of the discharge chamber does not cause a contamination that would result in appreciable decrease in the efficiency of the process of acceleration of bodies using an electric-discharge light-gas accelerator. It is determined that, with the launching velocities equal to or lower than the velocity of sound in the working gas, the actual values of launching velocity are 10–15% lower than the calculated (maximal) values.     

A renewable liquid droplet method for on-line pollution analysis by multi-photon ionization

A multi-photon ionization based fast conductance (MPI-FC) technique was applied to detect combustion byproduct aerosols. These PAH-polluted aerosols were on-line sampled by means of renewable water microdroplets. The environmental cases considered here have involved such common air contaminants as motor car exhaust gas and cigarette smoke. The possibility of obtaining useful calibration curves has been addressed. Two droplet contamination regimes were clearly observed. These have been argued to be associated with either a volume uniform (i.e., a bulk type) or a surface-favored contamination. The latter regime is possible whenever the increasing droplet contamination extends beyond the solubility saturation of the PAH compounds. Detection limits as low as 1 pg were obtained for pyrene-contaminated renewable microdroplets.     

Benefits of carbon addition on the hydrogen absorption properties of Mg-based thin films grown by Pulsed Laser Deposition

Mg-Ni thin films were grown using Pulsed Laser Deposition. In situ optical changes from shiny metallic to transparent states were observed for films deposited in vacuum and under an Ar/H₂ gas mixture (93/7%), respectively. Optical changes were also achieved by ex situ hydrogenation under hydrogen gas pressure of 15 bars at 200 °C. However, after ex situ hydrogenation, the optical transmittance of the Mg-based hydrogenated thin films did not exceed 25%. Such limitation was attributed to oxygen contamination, as deduced by High Resolution Transmission Electron Microscopy observations, showing the co-existence of both Mg-based and MgO phases for as-deposited films. A significant decrease in oxygen contamination was successfully achieved with the addition of carbon, leading to the preparation of (Mg-based)-C_x (x < 20%) thin films showing a faster and easier hydrogenation.     

Undesirable contamination in rf sputtered α-Si layers

Undesirable contamination in rf sputtered α-Si thin layers are detected by using a sensitive electron microprobe. Their presence is attributed to residual gases in the sputtering chamber. The residual contents in the chamber are identified by in situ mass spectrometry. Partial correlation is found between the gas phase residual impurities, and contamination in the solid α-Si layers.