氢氟烃混合物PVTx研究进展

综述了国内外对氢氟烃(HFC)混合物PVTx性质实验研究的进展；分析了目前混合物PVTx实验研究的三种常用实验方法：定容法，Burnett法和膨胀定容法。对实验中的一些常见问题及其解决方法进行了归纳。     

制冷混合工质气液相平衡试验用磁力循环泵的研究

在循环法气液相平衡试验中,循环泵用于输送气相或液相使系统充分混合并快速达到气液相平衡。本文针对高压制冷混合工质设计了一种磁力驱动循环泵,经试验测试能耐压6MPa,流量可以在0.18~0.55L/min连续可调,对循环流体无加热作用,能够满足制冷混合工质气液相平衡试验的需要。     

气泡雾化喷头流量特性实验研究

设计了一种气泡雾化喷头,利用喷头雾化性能综合实验平台,对喷头的流量特性进行实验研究。考察了压降、气液比、压力比对流量特性的影响,通过实验测量与拟合得到了气泡雾化喷头气液比与液体流量系数的经验公式。实验研究结果表明,压降与气液比、液气压力比与气液比、气液比与液体流量系数均成反比关系。压力比、气液比对于喷头的最终雾化效果具有很大的影响,气压为0.1 MPa时,当液气压力比低于1.045,此时气液比大于0.1,液体流量系数小于0.13。     

顶空气相色谱法分析水质中的挥发性卤代烃

从样品的采集、保存、纯水的制备、载气的纯度、顶空分析时的气液体积比、液上空间压力、气液两相平衡温度、平衡时间、液相浓度、样品的基质等方面 ,讨论了项空分析在定量方面需考虑的诸多参数 ,以便更好地提高水质中卤代烃顶空分析的灵敏度     

R1234yf/R134a二元混合工质的热物理性质

用PR方程结合vdW和HV混合法则建立了R1234yf/R134a的热物性模型,分析了混合物的气液相平衡特性曲线,发现R1234yf/R134a存在共沸点。当R1234yf/R134a的摩尔组分比为0.533/0.467,压力在400k Pa以上时,温度滑移最大约0.01K;当摩尔组分比为0.178/0.822,压力为200k Pa时,温度滑移最大为0.28K。根据余函数法导出了R1234yf/R134a的焓、熵计算式,可以用于R1234yf/R134a直接替代的工程研究。     

压缩空气泡沫灭火系统气液混合器的研究现状

阐述了压缩空气泡沫灭火系统的基本原理,重点介绍了系统中的关键核心部件气液混合器,以及对衡量灭火泡沫液的性能指标如析液时间、附壁能力和发泡倍数等作出释义.随后介绍了目前气液混合装置的研究现状,并总结了气液混合装置的设计方向,最后提出对气液混合器未来研究方向的展望.     

密封件对新型气液缸性能影响的研究

本文提出了一种新型气液缸和气液位置伺服系统。该系统采用气液连动控制,充分发挥液压与气动各自的优点,大大提高了位置控制精度。对气液缸的两种采用不同密封的结构进行实验研究,结果表明,不同的密封件直接影响着气液缸的性能     

轴承腔中润滑油气液两相分层流动研究

基于轴承腔中润滑油气液两相分层流动模型和湍流模型，采用VOF方法追踪气液界面等技术求解三维N—S公式，对腔内润滑油气液两相分层流动的特性进行了研究。分析了润滑油混合物空气体积比等结构工况参数对流体介质在轴承腔出口处压力和径向速度的影响，研究结果揭示了结构工况参数对出口压力和径向速度的不同影响趋势。将所计算得到的理论数据与国外类似结构的轴承腔工况条件和结构数据进行比较，证明了该计算方法和结果的正确性。     

一种新型离心式气液分离器分离性能的数值模拟与试验研究

为了研究该分离器的分离性能,通过搭建气液两级分离实验台架进行实验测量,同时应用计算流体力学(CFD)方法对分离器内的气液两相流动进行数值模拟.重点研究了流量、气液比、介质粘度、密度、气泡直径及转鼓转速等六个变量对离心式气液分离器分离效率的影响.通过比较数值计算与实验测定结果,验证了数值模拟方法的可行性.分析结果表明,预测的分离效率变化趋势与实测结果在总体上是一致的, CFD可作为离心式气液分离器设计的有效工具.     

液压油在线除气装置设计与试验

液压油中气体的存在,会影响液压系统的性能。该文基于漩涡流的离心原理设计了一种液压油在线除气装置,并开展了可视化试验工作。试验结果表明在一定流动参数条件下除气装置中气液两相流可以达到稳定状态,聚集的气体与排出的气体相平衡,能有效的去除油液中的气体。     

Novel refrigeration lubricants for use with HFC refrigerants

A series of fluorinated alkyl aryl ethers composed of hydrocarbon components, fluorinated alkyl groups and ether linkage groups were evaluated as refrigeration lubricants for use with hydrofluorocarbon (HFC) refrigerants. The novel structure of these lubricants eliminates the problems of poor stability and high moisture absorption that are associated with conventional refrigeration lubricants for use with HFC refrigerants, such as polyalkylene glycol or polyol ester, which have a polar structure. The fluorinated alkyl aryl ethers show high miscibility with HFC refrigerants, high stability, excellent lubricity, and low moisture absorption. These characteristics make fluorinated alkyl aryl ethers well suited to serve as refrigeration lubricants for use with HFC refrigerants.     

多元混合工质粘度计算

介绍了基于对应态原理建立的氮烃类多元混合工质的统一粘度模型     

Lubricity of environmentally friendly HFO-1234yf refrigerant

Global warming concerns have triggered the interest in alternative refrigerants for air-conditioning and refrigeration compressors. Newly developed refrigerant HFO-1234yf is an attractive and environmentally friendly candidate to replace existing hydrofluorocarbon refrigerants, such as R-134a. Herein, the tribological compatibility of gray cast iron material with this new refrigerant was investigated under aggressive unlubricated conditions. HFO-1234yf exhibits excellent performance compared to R-134a due to the formation of a fluorine-containing protective tribolayer on the topmost surface as X-ray photoelectron spectroscopy (XPS) analysis, inside and outside the wear tracks, revealed. The morphology of the layer was also studied using scanning electron microscopy (SEM) studies.     

三维打印成形粉末配方的优化设计

利用均匀设计方法对三维打印成形的粉末配方进行了试验研究,对试验数据进行回归分析,建立了粉末成分配方对制件性能的多元非线性回归方程。设计了粉末配方的多目标优化模型,利用MATLAB软件求解出最佳配方并通过试验加以验证。采用均匀设计试验进行回归分析和优化是安排多水平配方设计的良好方法。     

Prediction of forced convective boiling heat transfer coefficient of pure refrigerants and binary refrigerant mixtures inside a horizontal tube

Forced convective boiling heat transfer coefficients were predicted for an annular flow inside a horizontal tube for pure refrigerants and nonazeotropic binary refrigerant mixtures. The heat transfer coefficients were calculated based on the turbulent temperature profile in liquid film and vapor core considering the composition difference in vapor and liquid phases, and the nonlinearity in mixing rules for the calculation of mixture properties. The heat transfer coefficients of pure refrigerants were estimated within a standard deviation of 14% compared with available experimental data. For nonazeotropic binary refrigerant mixtures, prediction of the heat transfer coefficients was made with a standard deviation of 18%. The heat transfer coefficients of refrigerant mixtures were lower than linearly interpolated values calculated from the heat transfer coefficients of pure refrigerants. This degradation was represented by several factors such as the difference between the liquid and the overall compositions, the conductivity ratio and the viscosity ratio of both components in refrigerant mixtures. The temperature change due to the concentration gradient was a major factor for the heat transfer degradation and the mass flux itself at the interface had a minor effect.     

Large-scale Experimental System for Multiphase Fuel/Air Explosions

A large-scale experimental system for multiphase combustion and explosion study was developed and manufactured.The explosion tank consists of a 2 m diameter,3.5 m long tube and ellipsoidal domes on both ends.The volume of the experimental tank is 10 m3.Pressure histories of the explosion pressure can be measured at different locations in the tank.High pressure glass windows of 200～300 mm were used to have access to the visualization of the explosion process.The explosion process of methane/air mixture and methane/coal dust/air mixture initiated by a 40 J electric spark at the center of the tank was studied in the large-scale experimental system.Five pressure sensors were arranged in the tank with different distances from the ignition point.Ten dust dispersion units were equipped to eject dust into the tank.A high-speed camera system was used to visualize the flame propagation during the explosion process.The characteristics of the pressure wave and flame propagated in methane/air mixtures and methane/coal dust/air mixtures have been studied and analyzed.     

A Laser-Based Apparatus for Estimating the Hydrogen Diffusion Constant in Gas Mixtures

A laser-based apparatus for determining the hydrogen diffusion constant in gas mixtures is described. The main units of the apparatus are a diffusion chamber and a computer-based laser system for the selective diagnostics of hydrogen in gas mixtures by coherent anti-Stokes Raman scattering (CARS) in combination with biharmonic pumping based on stimulated Raman scattering. The diffusion constant is estimated by approximating the experimental data that describe changes in the hydrogen concentration with time at a fixed point in the diffusion chamber and comparing them to the exact solution to the diffusion equation for the chosen one-dimensional experimental geometry.     

Tribological Studies on Scuffing Due to the Influence of Carbon Dioxide Used as a Refrigerant in Compressors

Because hydrofluorocarbon (HFC) refrigerants in air-conditioning systems are known to have a negative effect on the environment, carbon dioxide (CO₂) is a candidate as a replacement refrigerant. Research work related to CO₂ as a refrigerant has been focused primarily on its thermodynamic performance, whereas work in the area of tribology related to carbon dioxide is absent. In this study, the effects of CO₂ used as a refrigerant on the tribological behavior of surf aces in contact in such systems were investigated. Controlled experiments were performed at constant loads in environments of CO₂ and the conventional HFC refrigerant, R134a, as well as under conditions of step-increasing loads in the presence of refrigerant (CO₂ or R134a) and polyalkylene glycol lubricant. The experiments were performed on a high-pressure tribometer that is particularly suited for tribological testing of compressor contact interfaces. The tribological behavior of contacting surfaces in a CO₂ environment was nearly identical to that in an R134a environment when tested under the same operating conditions.     

Tribological Study Comparing PAG and POE Lubricants Used in Air-Conditioning Compressors under the Presence of CO2

Polyalkylene glycol (PAG) and polyolester (POE) synthetic lubricants are good candidates for air-conditioning systems that work with alternative refrigerants such as carbon dioxide (CO₂). Both synthetic lubricants are widely used in air-conditioning compressors and have been optimized for use with hydrofluorocarbon (HFC) refrigerants. However, it is still not clear which lubricant is more suitable for use in compressors operating with CO₂ as a refrigerant. This study compares the performance of PAG and POE lubricants of the same viscosity (ISO VG 68) used in air-conditioning compressors. The materials used were Al390-T6 disks and hardened steel SAE 52100 pins. The tests were performed using a high pressure tribometer (pin-on-disk configuration) in the presence of CO₂. The results showed that scuffing and wear resistance of Al390-T6 tested with PAG were superior compared to the samples tested with the POE lubricant. Chemical analysis using X-ray photoelectron spectroscopy showed that PAG tends to promote the formation of carbonate layers on the surface, leading to improvement in the tribological performance of the interface.