制冷剂充注量及毛细管长度对空气源热泵热水器性能的影响

对一台空气源热泵热水器进行制冷剂充注量和毛细管长度的性能匹配试验。试验结果表明:在试验所取的制冷剂充注量和毛细管长度范围内,随着制冷剂充注量增大,制热量和COP先增大后减小,功耗则不断增大;随着毛细管长度增大,制热量、功耗和COP均是先增大后减小;当系统在最佳匹配时,COP达到4.14 W/W。制冷剂充注量和毛细管长度对制热量的影响相对较大,对功耗的影响相对较小,当制冷剂充注量和毛细管长度发生变化时,在差异程度最大时,制热量的变化率比功耗的变化率分别高183.3%和82.4%;在制冷剂充注量较大时,COP会明显下降。当制冷剂充注量较大时,在运行前期的水温增长速率比制冷剂充注量较小时高,在运行后期(约60 min以后)反而比较低。     

中间冷却器在氨系统中的应用

介绍中间冷却器在双级压缩制冷系统中的作用,并以氨制冷循环系统为例,计算说明合适的注液量不仅可使低压级的排气冷却到中间压力下的干饱和蒸汽,而且使节流前的氨液具有一定的过冷度,使制冷压缩机的功耗最小,制冷系数最高,并以实例进行计算说明。     

蒸气压缩制冷在高热流电子器件冷却中的应用

由于电子芯片技术的高速发展,集成度不断提高,芯片功耗大和散热困难的问题也凸现出来,传统的散热方法在一些超高热流密度场合已经不能：占效为芯片提供冷却。蒸气压缩制冷可望成为现代高热流电子器件及系统冷却的重要技术,国外主要电子系统公司均已采用蒸气压缩制冷来实现电子系统冷却。要使蒸气压缩制冷在电子系统中得到广泛应用,必须进一步研发高效紧凑的微型制冷压缩机、研制能与电子芯片紧密结合的微型蒸发器以及高效的冷凝器．     

空调器毛细管长度与制冷剂充注量匹配实验研究

通过实验的方法研究了空调器毛细管长度和制冷剂充注量对制冷系统性能的影响,得出了相应的曲线及KF-25W分体空调器毛细管长度和充注量之间的最佳匹配关系,该实验方法具有一定的普遍意义.     

无油线性压缩机变容量制冷性能实验研究

无油线性压缩机具有结构简单紧凑、效率高和寿命长等优点,在航空航天热控领域具有巨大的发展潜力。针对实验室研制的无油线性压缩机进行变容量制冷性能研究,分析行程和余隙容积变化对压缩机的制冷性能受的影响。实验结果表明,在冷凝温度为48℃,蒸发温度为10℃,热沉温度维持15℃,行程从6.5 mm增加到8.9 mm时,压缩机的制冷量会随行程的增大而增大。在行程为8.9 mm时,最大制冷量为180 W;系统的COP和压缩效率会随着行程的增大先增大后减小,在行程为7.9 mm时,具有最高COP和压缩效率,分别为1.78%和30.6%。在冷凝温度为55℃,蒸发温度为10℃,热沉温度稳定在15℃,系统的余隙长度从0.1 mm增加到1.1 mm时,随着余隙长度的增加,压缩机的制冷量、COP和压缩效率会逐渐降低。电机效率会随着余隙容积的增加先升高后降低,在余隙长度为0.9 mm时,电机效率为78.4%。     

基于变频压缩机的跨临界CO_2热泵热水器名义工况的试验研究

搭建基于变频压缩机的跨临界CO_2热泵热水器试验台。在系统制冷剂充注量为950 g,测试工况为名义工况的前提下,分析电子膨胀阀开度和压缩机运行频率对系统参数,包括压缩机吸气温度和压力,排气温度和压力,系统制热量和制热性能系数COP_h的影响。试验结果表明:随着电子膨胀阀开度的增大,压缩机吸气温度降低,吸气压力升高,而排气温度和排气压力趋势性走低,中间偶有起伏;制热量随着电子膨胀阀开度的增大逐渐降低,制热性能系数COP_h在电子膨胀阀一定开度范围内存在一个最优值;压缩机吸气温度受频率的影响较小,吸气压力则随着频率的增加而降低,排气温度和排气压力均随频率的增加而升高;制热量随着频率的升高而增大,制热系数COP_h最大值出现在低频率范围。     

充注量对小型CO2制冷系统影响的实验研究

为了研究充注量对小型二氧化碳制冷系统的影响,利用一套展示柜二氧化碳制冷系统,进行了不同充注量的实验。讨论了充注量对二氧化碳制冷系统吸排气压力、运行功率、吸排气温度的影响。同时,结合本系统,对假临界现象进行了分析,结果表明:充注量不足,蒸发、冷凝压力低,压缩机吸、排气温度高,系统COP较低;充注量过多,系统运行功率高,系统制冷系数降低;系统运行一段时间后,回热器热侧出口达到假临界温度,吸、排气温度产生突降;随着充注量的增加,吸、排气温度突降点前移。本研究可为跨临界二氧化碳制冷系统最佳充注量的确定及如何维持系统高效运行提供理论指导。     

CO_2跨临界制冷系统在饮料现调机中的实验研究

CO_2是一种不对臭氧层产生破坏,具有很小温室效应系数的自然工质。本文通过饮料现调机原理和特点分析,设计了应用于饮料现调机的CO_2跨临界制冷系统。根据CO_2压缩机运行范围,通过毛细管和CO_2充注量的组合实验,确定了适合饮料现调机的最佳毛细管长度和充注量。在设计工况下,CO_2冷系统运行的高低压均满足压缩机的安全运行区域,最后提出了批量商业化生产需要解决的问题。     

高/低压区氨水吸收/压缩复合制冷循环性能分析

针对氨水吸收/压缩复合制冷循环的方式不同,结合Schulz氨水溶液状态方程,分别对压缩机处于系统高压区和低压区两种不同的组合方式进行了理论分析计算。分析了蒸发温度、热源温度、冷却水温度和中间压力对两种组合方式下压缩机当量热耗量和热源耗热量的影响,并与单级氨水吸收制冷循环的性能系数做了比较。结果表明,压缩机当量热耗量对循环性能的影响要低于热源耗热量的影响;压缩机处于系统高压区时循环的一次用能量要明显高于压缩机处于系统的低压区;在中间压力给定时,存在一个最佳热源温度,使得氨水吸收/压缩复合制冷循环的性能系数取得最大值;随任一温度参数变化时,压缩机处于高压区时的性能系数总会出现低于单级氨水吸收循环性能系数的临界点;而压缩机处于系统低压区时循环的性能系数要高于高压区循环和单级氨水吸收循环。     

独立式过冷循环对改善单级蒸气压缩制冷系统性能分析

过冷循环是改善单级蒸气压缩制冷系统性能的有效途径。本文以基加利修正案后可选替代制冷剂为分析对象,对带独立式过冷循环的单级蒸气压缩制冷循环的压缩机单位容积制冷量、压力比、排气温度、压缩机功耗、系统性能系数、损失和效率随蒸发温度的变化规律进行分析。结果表明:在固定蒸发温度和固定冷凝温度时,存在最佳过冷度Tsopt使系统COP最大。在最佳过冷度下,独立过冷循环使得系统的性能系数COP明显增大,采用独立过冷循环使R744提高性能效果最明显,R717增大幅度最小。13种不同的工质中,R600a、R152a、R161、R134a、R1234ze系统性能系数COP高于R22。独立过冷循环使系统压缩机总输入功W和损减少, 效率η_χ明显增大。文章揭示了不同工质在引入独立过冷循环的单级蒸气压缩式制冷循环的变化规律,为单级蒸气压缩式制冷循环性能改进提供参考。     

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 Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

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.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

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.     

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.