冷冻水流量和温度对基于混合工质的双温冷水机组性能影响

为研究冷冻水流量与温度变化对基于大滑移温度非共沸工质双温冷水机组性能的影响规律,本文在大滑移温度非共沸工质的双温冷水机组实验台进行了多组实验研究。实验分别研究了非共沸工质R32/R236fa在不同质量组分比例(0.4∶0.6,0.5∶0.5,0.6∶0.4)下,冷冻水流量由0.25 m~3/h增大到0.45 m~3/h,以及高温冷冻水温度变化时,冷水机组性能的变化情况。实验结果表明,在冷却水进出口温度为32℃与37℃,高、低温冷冻水温度分别为7℃,16℃时,不同冷冻水流量下冷水机组的制冷效率(COP)最大为4.17,最小COP为3.27。此外,高温冷冻水温度变化对冷水机组COP存在明显影响。实验为大滑移温度的双温冷水机组的应用提出了数据基础。     

浸润式制冰系统和滑落式制冰系统能量分析

利用CoolPack软件对滑落式制冰系统和浸润式制冰系统进行分析,利用能量分析法对比评价两制冰系统中压缩机、冷凝器、节流阀、蒸发器的能量利用情况,并分析过冷度、过热度、蒸发温度、冷凝温度对整个系统损率和效率的影响。结果表明,浸润式制冰系统的效率较滑落式制冰系统提高约11.27%,制冷量提高约4.12%,适当降低蒸发器出口过热度、提高冷凝器出口过冷度、降低冷凝温度、提高蒸发温度均有利于提高机组性能。     

急速冷冻箱制冷性能实验研究

针对食品急速冷冻箱的制冷系统进行实验,研究其降温曲线及制冷性能。实验结果表明,目前的食品急速冷冻箱制冷系统在开始降温后,蒸发温度立刻降至接近最低蒸发温度,蒸发器进口温度和被冷冻水温度温差约为25℃,蒸发温度过低导致进入压缩机的制冷剂流量偏小,压缩机的实际功率只占额定功率的60%左右,系统的损主要发生在蒸发器内(约占41%),因此使蒸发温度与箱温匹配是提高急速冷冻箱降温速度的重要手段。     

低温热源驱动的二级吸附冷冻循环实验研究与性能分析

在冷冻应用方面,传统的吸附式制冷工质对在热源温度低于90℃、冷凝温度高于25℃的条件下,很难实现-10℃以下的冷冻。为了实现100℃以下的太阳能或废热利用,这里提出了二级吸附式制冷循环,建立了性能测试实验台。采用CaCl2-BaCl2-NH3作为工质对,利用85℃热源驱动,测试不同蒸发温度与冷凝温度下吸附剂的吸附与解吸性能。结果表明,二级吸附式制冷能够实现-20℃下的冷量输出,同时,冷却水温度为25℃时,氯化钙的循环吸附量、二级吸附式制冷COP与SCP分别为0.598kg/kg,0.24,106.6W/kg。     

R32替代R22制冷系统的分析

为从能量＂质＂的方面揭示R32替代R22的合理性,分别对使用R22和R32作制冷剂的制冷系统,在ARI 520标准的空调工况下进行分析,首先对整个循环系统进行分析,得到系统的效率和冷量,然后分析制冷循环各环节损失的原因,给出各环节的效率、损失和损失系数的计算表达式,并进行计算和比较。分析表明,R32的制冷系统更有利于能量的充分利用,而且主要是压缩环节损失明显减少,说明R32替代R22的可行性。     

基于数据中心余热回收的硅胶-水吸附式制冷系统的实验研究

数据中心蕴含丰富的低温余热资源,若将硅胶-水吸附式制冷机组运用于数据中心余热回收且给水冷背板系统提供冷量满足服务器CPU直接水冷的要求及水冷背板的需求,将具有显著的节能效果。本文针对45～60℃的低温热源,对吸附式制冷机组进行实验,测量换热流体在不同工况下的温度,结果表明:硅胶-水吸附式制冷机组能够将23℃的冷冻水降温至20℃以下,产生1.28～4 kW的制冷量,系统COP在0.22～0.51之间。若提高热水温度,降低冷却水温度以及适度提高冷冻水温度可使硅胶-水吸附式制冷机组提供更多的冷量,节能效果更佳。     

小型双蒸发温度冷/热水机组的运行调节特性实验

本文针对中小型住宅办公建筑在温湿度独立控制方面存在的不足,建立了一套基于双蒸发温度的新型冷/热水机组。实验研究了在改变压缩机频率（30～80 Hz）及高温与低温侧电子膨胀阀（EEV1、EEV2）开度（80%～100%、10%～50%）工况下系统的运行情况,记录供回水温度以及冷冻水流量并对高低温侧冷量进行分析,从而研究该冷/热水机组的运行调节特性。结果表明：变频制冷和制热工况下,机组制冷（制热）量均与压缩机频率呈正比关系;制冷工况下,当EEV2开度小于30%时,随着EEV1开度的增大,机组高低温侧制冷量和总制冷量呈下降趋势;EEV1开度固定时,随着EEV2开度的增大,机组高温侧制冷量基本保持恒定,低温侧制冷量和总制冷量呈先上升后下降的趋势,在EEV2开度约为30%时出现最大值,此时机组的除湿能力也达到最大。     

涡旋式压缩机在低温冷冻领域应用的实验研究

针对带HVE阀设计的半封闭卧式涡旋式压缩机,与当前冷冻市场上广泛使用的一款活塞式压缩机的性能进行对比测试。测试结果表明:由于喷气增焓的作用,随着系统压比的增大,涡旋式压缩机在制冷量方面表现出明显的优势。当蒸发温度为-25℃时,其制冷量与活塞式压缩机的比值,从25℃冷凝温度的约90%,提高到50℃冷凝温度的约130%。与活塞式压缩机相比,在上述运行工况下,涡旋式压缩机的性能也有所提升,当蒸发温度为-25℃时,R404A涡旋式压缩机的EER比活塞式压缩机的提高约2%~8%;R22涡旋式压缩机的EER比活塞式压缩机的提高2%~3%(冷凝温度为25℃时),冷凝温度为50℃时提高4%~5%。     

集中式双冷源温湿度独立控制空调系统的分析

介绍双冷源温湿度独立控制空调系统,并对该系统的高低温冷源负担的负荷进行分析。分析表明：该空调系统中高低温冷源负荷主要取决于第一机器露点。因此,进一步分析该系统的第一机器露点发现：机组能耗均随着第一机器露点的右移而减小,即高温机组冷冻水温度越高,系统越节能。该研究为空调系统的节能设计奠定了坚实的理论基础。     

R1234ze(E)在冷藏车余热驱动型TORC-制冷循环系统运行性能分析

建立了冷藏车余热驱动型跨临界有机朗肯-制冷循环系统热力学计算模型,研究了R1234ze(E)在该循环系统中运行性能,系统地分析了冷凝温度为40℃、50℃、60℃时系统运行性能参数,得到冷凝温度为40℃时,对应发动机尾气温度约为140℃时,系统拥有最高的膨胀机做功量10.20 kW;对应发动机尾气温度约为165℃,系统拥有最优的TORC系统热效率9.49%和最大的TORC-制冷循环系统制冷量18.36kW以及最佳的热效率值19.12%。     

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.