制冷系统油分离器分油效率测试方法的研究

制冷系统中,油分离器的分油效率决定压缩机运行的安全性。本文对制冷系统中油分离器的分油效率测试提出一种简单有效的试验方法,该方法是通过分别称量被油分离器过滤下来的油与未被过滤掉的油的质量,从而求得被检测油分离器的分油效率。最后通过对比分析试验数据和生产厂家的资料,验证该试验方法的可靠性和适用性。     

压缩机油分离器分离效率测试台的设计

压缩机油分离器分离效率的高低直接影响系统的制冷功效,设计了一套检测油分离器分离效率的试验装置,通过分别测量分离前后润滑油的质量,计算得出被检测油分离器的分离效率,为油分离器的关键性能指标提供了检测手段.     

商用水冷螺杆机组内置油分离器性能研究

针对商用水冷螺杆机组的内置油分离器,采用Fluent软件对冷媒两相流场进行了数值模拟。先用RNG k-!模型计算连续相的气态冷媒,得到油分离器内流场参数分布特征,再加入离散相的液态油滴进行计算。最终依据仿真数据,计算获得油分离器的分离效率,并分析影响油分离器分离效率的因素,为油分离器的优化设计提供理论依据。     

螺杆式冷水机组用离心式油分离器流场的数值分析

针对螺杆式冷水机组用离心式油分离器，利用Fluent软件对油分离器内两相流场进行数值分析。制冷剂气体选用RNG k-ε模型，液态油滴选用DPM离散相模型，分析叶片结构对离心式油分离器内部流场、压力损失和分离效率的影响。结果表明，倾斜叶片式油分离器的分离效果最佳，在入口流速为15 m/s,油滴直径为25μm时，分离效率为98.5%。     

空调用高效旋流油分离器仿真优化与实验

为了提高空调系统中旋流油分离器的分离效率、降低压力损失,本文对其结构参数进行了优化设计,通过流体仿真研究了油分离器内部各参数对分离效率和压力损失的影响,得到最佳的参数尺寸比例,并据此制作了一款新型油分离器,安装在空调系统中进行实验测试。实验结果表明:新型油分离器在回油工况(最低制冷剂流速)下分离效率由95.5%提高到99.0%,名义制冷工况下分离效率由97.3%提高到99.6%;名义制冷工况下压力损失由55.2 k Pa降低至23.1 k Pa;同时获得了油滴颗粒的分布函数。     

螺杆式空气源热泵机组压缩机油位试验研究

分析压缩机吸气回液、外置油分离器油分离效率对螺杆式空气源热泵机组压缩机油位的影响,提出改进翅片换热器分液、优化气液分离器结构、改善油分离器分离方式等改进措施,并对螺杆式空气源冷（热）水机组进行试验。结果表明,所提改进措施不仅能够提高压缩机运行过程中的油位,而且能够提高机组运行稳定性。     

旋风分离器在冷镦机油雾处理中的应用探讨

借助计算流体力学软件Fluent,探讨旋风分离器分离冷镦机产生的油雾的可行性。运用雷诺应力二次压力应变模型和离散相随机轨道模型对旋风分离器进行数值仿真,分析了流场、颗粒轨迹、油雾内PM2.5分离效率。结果表明:旋风分离器可作为冷镦机油雾处理的初级分离设备。     

分离器连续计量装置

分离器连续计量装置解决了低气井、低产液油井和间歇波动油井的产量计量问题,实现了真正意义上的连续计量,弥补了立式分离器量油装置技术上的缺陷,大大拓宽了立式分离器量油技术的适用范围.同时由于采用液位自动控制技术,自动化水平高,大大提高了计量工作的效率,有效降低了装置的计量误差,具有巨大的经济和社会效益.     

五类家用空调过滤网性能比较

家用空调过滤网是空调的重要组件,通过研究五类过滤网(尼龙初效过滤网;厚款为3mm薄款为1mm的静电滤棉HEPA初效滤网;折高为12mm的HEPA过滤纸;尼龙初效过滤网与薄款静电滤棉的叠加网)在不同风速(2.4m/s、2.7m/s和3.3m/s)、不同粉尘条件下(不加模拟粉尘和加1g粒径为16.9μm的粉尘)网的前后压差,并测定尼龙初效过滤网、薄款静电滤棉和叠加网对2g模拟粉尘的过滤效率,分析五类过滤网的差异,确定风阻较小且除尘率较高的过滤网。实验结果表明叠加网综合性能最好,过滤效率为69.23%,可为家用空调器过滤网的优化提供参考。     

浅析含泥沙原油计量问题的解决途径

通过改进双转子流量计的放置方向、更换轴承类型、优选过滤网目数的方法,逐步延长流量计在含泥砂原油中的使用寿命,充分发挥流量计在生产运行中的计量作用。同时,有效降低流量计的维修费用、检定费用和运输费用,提高计量准确度,使原油计量管理纳入正轨。     

基于局部三维Delaunay的插值网格边界增量构造算法

网格构造的质量和效率是插值于大规模测量点三角网格构造算法的关键,但在算法中既保证插值网格的三维Delaunay性质又实现网格的线性构造仍存在困难。笔者针对此问题,提出了基于局部三维Delaunay的插值网格边界增量构造算法,利用网格的局部Delaunay构造及其边界的循环膨胀、分裂及自裁减操作实现整个模型的自动构造。应用实例表明,算法在保证构造网格满足三维Delaunay性质的同时,线性构造任意拓扑结构的三角网格模型。     

Silicon-gap Fabry-Perot filter for far-infrared wavelengths

We developed a far-infrared Fabry-Perot filter constructed from a single silicon substrate. The limiting resolving power caused by beam divergence of a silicon-gap Fabry-Perot filter is approximately 10 times higher than that of a vacuum-gap Fabry-Perot filter because of the large index of refraction of silicon. The filter thus permits compact, high-throughput optical systems. Metal mesh patterns microlithographed on each face provide enhanced, wavelength-dependent face reflectivity. We tested the performance of filters with metal mesh patterns consisting of inductive crosses and capacitive squares. A Fabry-Perot filter developed for a rocketborne astrophysics experiment with a capacitive square metal mesh pattern achieves a resolving power of λ/Δλ(FWHM) =160 at λ= 158 μm, with a peak transmittance of 37% over an active aperture of 6.9 mm for an ?/3.8 optical beam at 15° incidence. The absorptivity of a 240-μm thick silicon substrate patterned with capacitive metal mesh is A ? 1% per pass, including loss in both the silicon and the metal mesh.     

一种可实现不平衡量快速测试的带通滤波器

针对全自动电机转子动平衡机中的不平衡量测试效率问题,设计了八阶有源带通滤波器,将其与二阶有源高通滤波器及窄带跟踪滤波器进行了实验比较。结果表明二阶有源高通滤波器在采样周期数较高时有很好的测试精度,可用于测试精度要求高,但测试效率没有要求的场合;窄带跟踪滤波器的重复精度较差,只能用于一般的平衡测试机;八阶有源带通滤波器具有较高的测试精度、测试重复性和测试效率,达到了日本同类机器的“幅值±3mg、相位±1º和5秒/次的测量时间”的测试水平     

Analysis of the performance of a sintered stainless steel wire mesh filter for cryogenic liquid purification

As a traditional and mature solid-liquid separating technique, filtration has been adopted in cryogenic liquid purification system owing to its low energy cost, simplified system, long lifetime and high purifying efficiency. Whereas, few data or result of filtration performance at low temperature is put forward in literatures, most of which are related to room and high temperatures applications. Furthermore, as an excellent cryogenic material, stainless steel medium is suitable for cryogenic liquid filtration, which is also seldom reported. In this paper, we propose a filtration system for purifying CO₂ particles from liquid nitrogen using a sintered stainless steel wire mesh filter with a nominal filtration degree of 0.5 μm, and characterize the separation behavior of this kind of filter medium at cryogenic temperature. Experimental results show that the whole filtration process can be divided into three stages with sufficient particle concentration in the feed slurry according to the evolution of pressure drop. Differences between surface filtration and depth filtration are demonstrated, and the influence of growth of filter cake is characterized. Pressure drop increases with increasing feed slurry flow and CO₂ concentration, and evolution tendency of filtration efficiency is affected by its calculation method. By comparison with the filtration at room and high temperatures, the effects of temperature on the fluid and media are emphasized.     

Transparent Nanofibrous Mesh Self‐Assembled from Molecular LEGOs for High Efficiency Air Filtration with New Functionalities

Alarming levels of particulate matter pollution in air pose a serious health threat in several countries, therefore intriguing a strong need for an economic and a viable technology of air filtration. Current air purification technology is rather expensive with certain types even having the risk of emitting hazardous by‐products. The authors have developed a multifunctional air filter inspired from the nasal hairs possessing an ability to specifically trap/exhale the foreign particles and allergens while still letting the air flow. This design is achieved by introducing different functionalities at different dimensional scale employing a bottom‐up approach starting with an organic molecule which is further self‐organized to form nanoparticles and ultimately to a nanofibrous mesh. While the molecular building block inherently possesses the property of shielding Ultraviolet (UV) rays, the nanofibrous mesh built up from it aids in trapping the particulate matter while maintaining good air flow. By controlling the concentration of the organic molecule, the formation of fibers has been enabled in the nanoscale regime to obtain high particle‐capture possibilities. The self‐assembled nanofibrous filter thus designed has achieved a high filtration efficiency of ≈90% for the PM 2.5 particle in congruence with the ability to block the harmful UV radiations.     

A polygonal finite element method for modeling arbitrary interfaces in large deformation problems

In this paper, a polygonal-FEM technique is presented in modeling of arbitrary interfaces in large deformations. The method is used to model the internal interfaces and arbitrary geometries using a uniform non-conformal mesh. The technique is applied to capture discontinuous deformations in the non-conformal elements, which are cut by the interface in a uniform regular mesh. In this approach, a uniform non-conformal mesh is decomposed into sub-elements that conform to the internal interfaces. The geometry of interface is used to produce various triangular, quadrilateral and pentagonal elements at the intersection of interface with regular FE mesh, in which the extra degrees-of-freedom are defined along the interface. The level set method is employed to describe the material geometry on the background mesh. The technique is used to extrude any arbitrary geometry from an initial background mesh and model under different external effects. An important feature of the technique is the decomposition of the uniform non-conformal mesh to the polygonal-FEM mesh, which is conformed to the material interfaces. Finally, several numerical examples are analyzed to demonstrate the efficiency of proposed technique in modeling arbitrary interfaces in large deformations.     

Analysis of transmitting characteristics of high-transparency double-layer metallic meshes with submillimeter period using an analytical model

The transmitting characteristics of high-transparency double-layer metallic meshes with submillimeter period were analyzed using an analytical model, which was established using angular spectrum propagation theory and verified through experiments. It was found through analysis that rotating misalignment has significant effect on the distribution of diffraction spot intensity. Large period and small linewidth can be used to obtain high transmittance and low levels of stray light. Substrate thickness has little effect on transmitting characteristics of mesh, and so it is a variable free to choose in optimizing shielding characteristics of mesh. We think, together with other ways and means of optimizing shielding characteristics of mesh, the model can also be used for the optimization of a high-pass mesh filter.     

Topology optimization using a continuous density field and adaptive mesh refinement

A new method of topology optimization is introduced in which a continuous material field is combined with adaptive mesh refinement. Using a continuous material field with different analysis and design meshes allows the method to produce optimal designs that are free of numerical artifacts like checkerboard patterns and material islands. Adaptive mesh refinement is then applied to both meshes to precisely locate the optimal boundary of the final structure. A Helmholtz‐type density filter is used to prevent the appearance of small topological features as the mesh refinement proceeds. Results are presented for several test problems, including problems with geometrically complex domain boundaries.     

Filter Capacity Predictions for the Capture of Magnetic Microparticles by High-Gradient Magnetic Separation

We present experimental and theoretical methods to predict maximum and working filter capacities for the capture of superparamagnetic microparticles through high-gradient magnetic separation (HGMS). For this, we employed various combinations of nine different HGMS filter matrices and two types of superparamagnetic microparticles. By calculating the separated particle mass per filter mesh area, we clearly demonstrated the influences of wire diameter and wire mesh spacing on the particle build-up density. Here, we introduce a simple experimental method for estimating average build-up densities in HGMS. Together with known physical parameters of the filter matrix and the background field, such average build-up densities allow good predictions of the operational working filter capacities.      

凝聚式单分散气溶胶发生技术的探讨

实现高效空气过滤器计数法的首要任务就是选择合适的气溶胶发生器。本文中首先介绍了凝聚式单分散气溶胶发生器的工作原理、构造形式、发生流程以及国内外研究进展,然后详细分析了其发生气溶胶粒子粒径和浓度的影响参数;作者认为凝聚式单分散气溶胶发生器能够快速地发生浓度可调的、适用于高效空气过滤器效率测试的单分散亚微米气溶胶粒子,可以满足国家标准《高效空气过滤器性能试验方法》的修订对气溶胶发生装置的要求。