吸收式制冷机发生器中沸腾换热特性研究进展

吸收式制冷机可以通过低品位热能驱动,在缓解当今社会能源消耗量大,电力供给紧张和环境日益恶化的问题上具有明显优势,因此受到了越来越多的关注。制冷工质对是吸收式制冷技术发展的关键,以找到一种环境友好、运行效率高、适用范围广的制冷工质对为发展方向。而沸腾换热性能研究又是制冷和化工行业中的基础研究,因此有必要对制冷工质对在发生器中的沸腾换热性能和沸腾换热关联式进行归纳总结。本文将从常用制冷工质对的沸腾换热性能和其他制冷工质对的沸腾换热性能两方面进行阐述。回顾这两方面的研究现状,讨论实际应用的可行性并对未来的发展方向提出建议。     

吸收式制冷工质的发展

吸收式制冷机诞生至今已有一百多年的时间了，在这一百多年中，吸收式制冷技术获得了长足的进步和发展。与此同时，吸收式制冷机制冷工质的选择及改善作为吸收式制冷技术的核心组成部分也得到了不断的完善和发展。吸收制冷工质对选择的每一次突破，都对吸收式制冷技术的进步产生了巨大的推动作用。本文简要回顾了吸收式制冷工质的发展过程，分析比较了当今正在研究或使用的主要工质对，同时也介绍了我们浙江大学制冷与低温工程研究所正在研究的Ｒ２２／ＤＭＦ（二甲基甲酰胺）和Ｒ２２＋Ｒ１４２ｂ／ＤＭＦ工质对的有关情况。     

三压力喷射吸收式制冷循环分析

本文分析了新型的三压力喷射吸收式制冷循环的特点,以R600/DMF,R22/DEF TEG为例说明了新循环相对于传统的吸收式制冷循环的突出优点,同时指出了利用混合制冷工质有利于新循环制冷效率的进一步提高。     

吸收式制冷技术的研究与应用

简单回顾了吸收式制冷技术的发展背景;较详细地介绍了国内外吸收式制冷技术的研究热点,主要包括对新工质对、吸收循环、传热与传质、智能化控制方式等几方面的研究。目前,溴化锂吸收式机组已经被广泛地应用于空调系统,本文对其在国内外的应用现状进行了详细介绍,主要包括热电冷联产、直燃型吸收式冷热水机组、蒸汽型吸收式冷水机组、热水型吸收式冷水机组、太阳能吸收式机组等：最后对吸收式制冷技术的前景进行了展望。     

扩散吸收式冰箱中制冷工质对性能的影响

利用非氟利昂类混合制冷的多能源扩散吸收式制冷系统日益受到人们的重视。着重论述了氨、氢、水三种工质系统以及各工质的最佳参数选择分析。介绍了压力选择原则、工质充量对性能的影响、加入防腐剂的考虑、新工质的扩散吸收式制冷系统。同时,对氨、硝酸锂、氢三工质系统的研究提出了一些参考意见。     

太阳能吸收式制冷技术发展现状及展望

在综述国内外太阳能吸收式制冷技术现状的基础上,从制冷机组形式、集热器类型、蓄能系统和辅助热源等方面介绍太阳能吸收式制冷技术的特点和发展现状,并对典型装置的应用进行总结,最后指出太阳能吸收式制冷技术的发展方向。     

离子液体用于吸收式制冷系统的筛选

在传统的吸收式制冷系统中,最常用的工质对是LiBr/H_2O和NH_3/H_2O。然而,LiBr/H_2O工质对具有腐蚀和结晶的问题,NH_3/H_2O工质对则面临着NH_3本身有毒和需设置精馏装置等问题。离子液体作为一种新型的吸收剂可以有效地避免采用上述工质对所带来的弊端。研究和开发适合的离子液体/制冷剂工质对是吸收式制冷发展的一个重要方面。针对用于吸收式制冷系统的离子液体,从物性到循环特性的国内外研究进展进行了综述,并从应用于吸收式制冷系统的角度给出筛选工质对的建议。     

强吸水性离子液体-水工质对吸收式制冷循环性能分析

离子液体的出现,为吸收式制冷循环工质的改进开辟了新途径。以离子液体-水为工质对的吸收式制冷循环性能与离子液体的吸湿性能密切相关,因此筛选两种对水有极强吸收性能的离子液体：1-乙基-3-甲基咪唑醋酸盐（[EMIm]Ac）、1-己基-3-甲基咪唑氯盐（[HMIm]Cl）,对其水溶液吸收式制冷循环进行研究。首先对离子液体水溶液热力学特性（蒸汽压、比热、比焓等）进行了研究,然后分析吸收式制冷循环的性能系数。研究结果表明这两种离子液体-水工质对单效吸收循环可工作于较高温度条件下,其性能系数大大优于现今国内外学者所研究的离子液体,其中[EMIm]Ac水溶液优于[HMIm]Cl水溶液。与传统工质溴化锂-水比较,[EMIm]Ac-水工质对在发生温度为100℃时具有相当的循环性能系数,且在较高温度条件下优于传统溴化锂-水的性能系数。然而该离子液体水溶液优势只在较高发生温度时才能体现,要实现技术上的进一步突破,应着重筛选低温区蒸汽压特性优良的水溶性离子液体。     

气泡泵在制冷技术中的应用研究进展

本文回顾了气泡泵研究的相关文献,简要的介绍了气泡泵工作原理,并对应用于扩散-吸收式制冷技术、Einstein循环制冷技术、吸收式制冷技术和太阳能制冷技术的气泡泵研究进展进行总结。提出气泡泵的重要影响参数有结构形式、运行参数和工质三种,并指出气泡泵的基本理论、运行特性和性能提升方法需要更完善和深入的研究。     

汽车废热吸收式制冷技术研究进展

针对汽车发动机废热驱动的吸收式制冷的研究现状和存在的主要问题进行探讨。首先,介绍当前汽车废热吸收式制冷循环的理论与试验研究、所用工质对,以及汽车废热吸收式制冷系统的部件研究;其次,分析当前限制其应用的因素,并指出汽车废热吸收式制冷技术的研究方向,以期对今后汽车废热吸收式制冷技术的研究提供借鉴。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

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.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

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.