脉动压力诱导注塑聚丙烯-纳米CaCO_3复合材料的性能

采用电磁动态注塑成型机脉动压力诱导注塑成型聚丙烯(PP)-纳米CaCO3复合材料,通过调节加工过程中的振幅和振动频率,研究了纳米CaCO3在PP中的分散性能及由此引起PP-纳米CaCO3复合材料力学性能和结晶行为的变化,探讨了振幅和振动频率对PP-纳米CaCO3复合材料性能的影响。实验结果表明,随振幅和振动频率的增加,纳米CaCO3在PP熔体中分散得更均匀,PP-纳米CaCO3复合材料的拉伸强度和冲击强度比稳态(未施加振动)注塑试样分别提高了17.1%和14.3%,PP-纳米CaCO3复合材料的熔点升高,并对其影响机理进行了分析。     

新型轿车电动玻璃升降器箱与盖注塑模设计

新型轿车电动玻璃升降器的塑料箱与盖,是升降器传动机构的组装与支撑件。箱与盖的孔与孔位精度,决定着传动机构的性能和精度。在提供了样品的情况下,接收方提出供给方所生产的升降器要与进口产品能通用的要求。箱与盖注塑模设计的过程中,根据样品上模具结构成型痕迹和注塑件的形体分析,确定了注塑模的结构。实践证明,所加工的箱和盖与样品达到了一致,实现了与进口件混装的要求。     

继电器罩壳注塑模具设计

介绍了一款继电器罩壳的注塑模,产品形状较复杂,外观要求较高。模具采用动模三面侧向抽芯机构,脱模机构采用推杆推出,借助模流分析软件Moldflow,分析了继电器罩壳注塑成型时的最佳浇口位置,进浇点数、冷却及翘曲变形情况,确定了侧浇口的进胶位置,保证了制件成型质量,模具设计中充分利用标准件、常规件,简化了模具结构。     

山东温石塘地热田回灌补源压裂增注试验

地热田回灌补源是实现地热能资源可持续开发的新技术,用于解决地热能补给,提高地热能利用率。其方法是在距开采井一定距离,施工一眼注水井,通过注水井向地下注入一定比例的水量与热源再交换,提高热能资源量。介绍了对注水井实施压裂、增加对地热井注水量的新工艺。经水力压裂和抽水试验,增注水效果明显,为我国合理开采利用和保护地热能资源提供了一种新的技术方法。     

Large eddy simulations for radiation-spray coupling for a lean direct injector combustor

Large Eddy Simulations (LESs) for a lean-direct injection (LDI) combustor are performed and compared with experimental data. The LDI emissions characteristics, and radiation-spray coupling effect on the predictions are analyzed. The flamelet progress variable approach is employed for chemistry tabulation coupled with a stochastic secondary breakup model. Good comparisons are shown with the experimental data mean and root mean square for both the gas phase and spray droplets profiles. The effect of combustion is found to change the shape and structure of the central recirculation zone to be more compact in length but larger in diameter in the transverse direction. In-addition the results show that the gas phase radiation alters the spray dynamics by changing the local gas-phase temperature distribution. This impacts the spray evaporation rate, the local mixture fraction, and consequently the combustion heat released rate and the predicted emissions. The simulation with no radiation modeling shows over prediction in the temperature distribution, pollutants emissions, higher fuel evaporation rate, and narrower range of droplet size distribution with lower number density for the smaller size particles. The current study suggests that, even for low pressure systems, radiation modeling can be important for accurate emissions prediction.     

Crystallization behavior and molecular orientation of high density polyethylene parts prepared by gas‐assisted injection molding

The dependence of hierarchy in crystalline structures and molecular orientations of high density polyethylene parts with different molecular weights molded by gas‐assisted injection molding (GAIM) was intensively examined by scanning electron microscopy, two‐dimensional wide‐angle X‐ray scattering as well as dynamic rheological measurements. The non‐isothermal crystallization kinetics of the samples were also analyzed with a differential scanning calorimeter at various scanning rates. It was found that oriented lamellar structure, shish‐kebab and common spherulites were formed in different regions of the GAIM samples. The scanning electron microscope observations were consistent with the two‐dimensional wide‐angle X‐ray scattering results and showed that the molecular chains near the mold wall had strong orientation behavior, revealing the distribution of the shear rate of the GAIM process. The differences in crystal morphologies can be attributed to molecular weight differences as well as their responses to the external fields during the GAIM process. The formation mechanism of the shish‐kebab structure under the flow field of GAIM was also explored. Copyright © 2012 Society of Chemical Industry     

Structure of evaporating single- and multicomponent fuel sprays for 2nd generation gasoline direct injection

In the present paper the effect of fuel properties on spray formation and evaporation was investigated for a hollow-cone spray of a piezoelectric injector for Direct Injection Spark Ignition (DISI) engines. Late injection timing in a high-pressure atmosphere (1.5 MPa, 200 °C) was simulated in an injection chamber. Liquid and vapor phase structure of the hollow-cone spray were studied with 2D-Mie scattering, laser-induced fluorescence (LIF) as well as phase-Doppler anemometry (PDA). The spray structure was investigated for several alkanes with high and low volatility (n-hexane, n-heptane, iso-octane, n-decane) and a three-component mixture of the n-alkanes with similar fuel properties like a multicomponent gasoline fuel. It is found that the rapid evaporation of high volatility fuels can lead to spray destabilization, whereas low volatility single-component fuels overestimate radial spray propagation and vortex formation. For iso-octane the droplet size distribution is shifted to smaller droplets and the spray appeared to be less dense compared to n-heptane despite almost identical boiling behavior. However, the much higher viscosity of iso-octane determines the internal nozzle flow which results in a reduced injected fuel mass and changed atomization. A well defined three-component fuel models the global spray characteristics as well as the droplet size, droplet momentum distribution and evaporation behavior of the used multicomponent gasoline fuel very precisely. Small amounts of low volatility fractions delay the droplet evaporation and support the overall spray stability also for multicomponent mixtures. This leads to an increased spray width as well as larger droplet sizes and momenta. The evaporation characteristic of multicomponent fuels at increased ambient pressure is complex. At the studied injection conditions it is situated between the two limiting cases of distillation-like behavior and coevaporation of the components. Moreover, the results in comparison with theoretical estimations indicate a demixing of light and heavy boiling fractions in the three-component and multicomponent fuel under conditions which are typical for DISI strategies with late injection.     

Flux Enhancement in a Helical Microfiltration Module with Gas Injection

Abstract

A helical flow module with an inner rod mounted membrane was designed and built to reduce gel layer deposit and membrane fouling during microfiltration. Controlled centrifugal instabilities resulting from flow in a helically grooved channel, as well as the leakage flow between adjacent grooves, generated secondary vortex flows. The permeation fluxes for helical modules with Dean vortex flow were compared with flat crossflow modules at different operating pressures, concentrations, and feed flow rates. The permeation flux of the helical module for a feed solution containing 0.3 wt% kaolin solution at 1.2 bar was 57% higher than that of the flat module. Moreover, in addition to secondary vortex flow, compressed air was introduced to the membrane module. The increase in flux for the helical module with air injection was significant: the flux enhancements at 1.3 bar, 2 L‐solution/min and 1.3 L‐air/min for 0.1 wt% solutions of kaolin and bentonite were 47 and 73%, respectively.     

出口内置式等离子体破裂防护快速充气阀的研制

为了进一步缩短阀门的充气时间,在外置式快阀成功研制的基础上,中科院等离子体物理研究所又成功研制出了出口安装在装置内部的快速充气阀,该阀在保留外置式快阀快响应、大流量优点的基础上,把阀门气体出口位置设计为可以安装到装置内部,这种结构设计一方面避免了由于采用管道而导致的时间延迟,缩短了充气时间,另外一方面也提高了出口气体的压力,更有利于等离子体破裂缓解.该阀的成功研制不仅为先进超导托卡马克装置开展等离子体破裂缓解研究提供了有效的工具,也使实时的等离子体破裂缓解成为了可能,更为未来大中型托卡马克装置开展类似的研究提供了有益的借鉴.     

镍电极对葡萄酒中乙醇测定的研究

葡萄酒经过固相萃取分离出有机酸根等干扰物质后,以镍电极脉冲安培法,结合流动注射技术,测定乙醇含量。方法的回收率为101.2% ～103.4% ,线性动态范围为10- 5～10- 3M,检测限(S/N= 3)为1×10- 6M。