节流短管流量特性试验研究

通过试验研究R22流过节流短管的流动特性,分析影响节流短管中制冷剂流量的几个重要因素;上游压力、下游压力、上游过冷度和短管直径。试验结果表明,当节流短管的下游压力小于上游温度所对应的饱和压力时,制冷剂出现壅塞现象,此时制冷剂流量不再受下游压力变化的影响;上游压力、上游过冷度、短管直径对制冷剂流量的影响较大。     

节流式流量计流出系数准确性研究

本文在深入分析节流式流量计流出系数特性的基础上 ,提出了用动态流出系数提高流量测量精度的方法 ,对节流式流量计的具体应用 ,提高流量测量精度和范围度等具有指导意义     

短管节流流量特性实验研究

通过毛细管与短管节流气态流量特性的实验研究,对比分析两者的气态流量特性,得出节流短管气态流量与孔径的函数关系,证明节流短管内制冷剂的流量函数与N2的流量函数类似,短管节流与毛细管节流具有相似的气态流量特性,可以将节流短管当作长度较短的毛细管进行研究。     

两级压缩制冷循环热力分析

在相同制冷工况条件下,对四种两级压缩制冷循环的制冷系数进行了理论推导和分析,对不同的中间冷却型式和节流型式进行了系统的分析和比较,为实际应用中的选择提供了理论依据,同时获得了两级压缩制冷循环的特点,在选用中间冷却方式时要首先考虑制冷剂的因素,在制冷剂允许的条件下,尽量采用中间完全冷却,因为在相同条件下,这种方案的制冷系数较大;在选择一次节流或两次节流时,不必考虑制冷剂和制冷系数的因素,而应综合考虑系统其他因素.在实际问题中,具体问题具体分析,综合考虑各方面的因素,确定最优化方案.     

空气源热泵热水器系统性能分析

为了预测空气源热泵热水器的运行性能,提高系统稳定性和降低能耗,建立空气源热泵热水器系统仿真模型,在焓差实验室对一台水箱容积为150L的一体式空气源热泵热水器样机进行变工况实验以验证模型的准确性,利用所建立的模型研究蒸发器入口空气流速及制冷剂质量流量对机组性能的影响。结果表明:系统制热量和COP都随环境温度的升高而不断增大;系统制热量随蒸发器入口空气流速的增大而呈增大趋势,在达到某值后,系统制热量变化趋于稳定;系统COP随制冷剂质量流量的不断增加呈先增大后减小的趋势,即制冷剂质量流量存在最佳值使得热泵性能系数最高。     

气液两相流流型振荡诱发制冷循环不稳定性的实验研究

研究利用变制冷剂流量制冷循环的实验平台结合流动显示方法发现:1)蒸发器出口的制冷剂气液两相流流型存在过热蒸汽流和雾状流两种型式,二者之间存在一个转变过渡区域,此时,两种流型闪动交替出现,回气温度随机性波动;2)膨胀阀出口(即蒸发器入口)的制冷剂气液两相流的流型存在液一气分相流、泡一气分相流两种型式,二者之间也存在一个转变过渡区,此时两种流型交替出现,制冷循环周期性振荡,蒸发温度、回气温度、排气温度等参数周期性波动:且振荡周期随着制冷循环制冷剂流量的增大而缩短.     

制冷系统毛细管节流特性的试验与分析

在一台采用旋转式压缩机的某品牌KC-25窗式空调器上,进行了毛细管节流特性的试验研究,得出了毛细管节流对空调器性能的影响以及气态制冷剂在毛细管中流动时的能量损失规律,经过DPS数据处理,拟合出了毛细管的流量随内径长度的变化曲线及其变化率曲线,推导出了其韦泊分布函数.为空调器的优化设计匹配,提高空调器的性能奠定了基础,为毛细管批量生产的质检提供了一些有益的参考.     

小型分体式空调器制冷潜热量利用的探讨

本文阐述了以氟里昂22为制冷剂的小型风冷式毛细管节流空调器(以下简称空调器)在制冷状态下,利用制冷潜热量(蒸发器上析出凝露水冷量)对毛细管节流前冷凝器出口侧的液态制冷剂进行冷却处理,以提高空调器的制冷系数ε和能效比EER的原理和方法,同时对相关问题作一些说明.     

GM制冷机预冷的氦节流制冷机流程研究（英文）

对采用GM制冷机作为预冷级的小型4He节流制冷机进行了设计及数值分析,对气体质量流量与节流孔径,节流制冷能力与高压侧压力、预冷机二级温度之间的关系进行了计算和分析。对节流压缩机的功率随排气压力,预冷机所需冷量随制冷剂质量流量变化的趋势进行了研究。通过以上分析和研究,给出了小型氦气节流制冷系统设计流程及主要部件的参数。     

变径毛细管在R410A冷暖空调器中的流量特性

为减少变径毛细管在R410A冷暖空调器应用中的匹配实验工作量,利用节流元件制冷剂流量测试台对多个结构尺寸规格的变径毛细管进行了R410A制冷剂流量测试,建立了基于阻抗计算方法的流量特性经验模型。利用该模型计算出KFR-32GW冷暖空调器所需变径毛细管的初步结构尺寸,并在该冷暖型空调器上进行精确匹配实验,确定最佳变径毛细管结构尺寸。实验结果表明:采用变径毛细管节流的空调器相对采用毛细管组件节流的空调器,制冷量减少0.3%,制冷能效比不变,制热量增加0.5%,制热能效比减少0.3%,两者的性能指标基本相同。因此变径毛细管可以代替毛细管组件应用于R410A冷暖空调器,且通过实验方法建立的变径毛细管R410A制冷剂流量特性经验模型精度较高,可以满足实际工程应用。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.