空气源热泵地暖系统冬季应用研究

本文研发了3P变频单元式空气源热泵机组,进行了民宅地板辐射供暖系统设计和冬季93 d的供暖应用实验。期间室外环境温度的变化范围-10~16℃,平均值3.72℃;热泵机组制热量变化范围3.82~10.06 k W,平均值6.71 k W;热泵压缩机的吸/排气压力的平均值为0.55 MPa/2.28 MPa,压缩比小;EER变化范围2.32~4.71,平均值3.46,能效较高。测试了室内0.1、1、1.5、2 m高度处的温度,平均值分别为20.48、19.26、18.75、18.01℃,呈现相对稳定的下暖上凉的温度场。进行了最暖、最冷2个典型气象日热泵系统运行性能的对比分析,两日室外的平均温差为17.21℃,最暖日制热量和EER分别是最冷日的41.9%和159%,室内温度相对稳定,表明热泵系统具有良好的环境适应性和舒适性。与城市集中供暖及燃气锅炉供暖相比,运行费用分别降低39.82%、56.17%,节能、安全、热舒适性更佳。     

基于中间补气压缩机的地暖系统制热性能实验研究

本文将中间补气涡旋式压缩机应用于地暖制热系统,以解决地暖制热系统在低温环境下制热性能不佳、机组运行不稳定等问题,并建立补气地暖样机实验系统,研究了在不同运行工况下中间补气地暖系统的压缩机排气温度、制热量、功耗及制热COP等参数,分析了中间补气地暖系统制热性能与常规热泵制热性能之间的关系。实验结果表明:当环境温度处于-20~7℃之间时,带中间补气系统的地暖机组的制热量相比于普通热泵平均提升约26.2%,制热COP平均提升约为8.7%,功耗仅平均增加约16%;当室外环境温度为-20℃时,压缩机排气温度降低了12℃。可见采用中间补气技术的地暖系统在低能耗的条件下更能满足低环境温度的需求。     

空气源户式机组地板采暖系统应用研究

为了研究空气源热泵冷热水机组作为地板采暖的热源的运行特性,以一围护结构保温良好的房间为研究对象,分别测试了热泵机组采用低水温进行供暖运行时的能效、在高低温的运行环境下供暖房间内温度的变化。结果表明,在保温性能良好的建筑,采用热泵机组以35℃的低供水温配合高效地暖盘管进行地板供暖,既能保证室内的舒适性,又具有良好的节能效果。得出用于地板采暖的空气源热泵机组,其控制开停机的温差需要比传统的空气源热泵机组大,在低温环境下,机组性能衰减的特性对室内达到相同供暖效果所需的时间影响不大,为设备、工程设计提供参考。     

低温空气源热泵热水机在太原旅馆建筑中的全年实测性能

本文对太原一座旅馆建筑中安装的低环境温度用空气源热泵热水机进行了为期一年(2014年1月18日-201 5年1月17日)的实地测试,获得了该热泵热水机全年的运行性能和运行规律:热泵热水机全年运行正常;在冬季典型测试月内机组制热量平均值为24.5 kW,逐月能效比(HMPF)为2.78,过渡季典型测试月的机组制热量平均值为35.3 kW,HMPF为3.46,夏季典型测试月的机组制热量平均值为39.1kW,HMPF为3.97;热泵热水机在各月份的运行时长没有明显的季节性差异,且每天的运行规律在各个季节也基本一致。     

行为模式对户式空气源热泵地暖系统供热性能的影响

自主调节供水温度及开关部分供暖回路阀门等行为模式对户式空气源热泵地暖系统的节能与舒适性具有重要影响。本文以一实际住宅为例,实验研究了户式空气源热泵地暖系统在不同供水温度和改变供暖回路数量下的供暖特性,对室内空气温度、地面温度及系统耗电量等参数的实测与分析显示：室外平均温度为-2.3℃,按照机组最高供水温度55℃运行时,由于地面温度过高,地板表面温度局部不满意率超过20%,相对于供水温度30℃运行结果,耗电量增加191%,客厅与书房的温差增加2.5℃以上。室外平均温度为-1.7℃,关闭次卧和客卧相应的地暖回路阀门后,主卧、客厅和书房室温比全屋供暖时分别降低了1.4、2.9、0.5℃,系统耗电量降低18.7%。     

热泵空调器低温制热的探讨

热泵是依靠消耗机械功而把室外环境中的低温位热量连同消耗的功转移到需要较高温度的某一区域中去的设备。按照逆卡循环的结果,其制热量Ｑ２＝室外环境吸热Ｑ１＋消耗功Ｗ,如图１所示。当然,热泵空调器在实际工作中,其制热量应扣除室外机组的散热。热泵空调器蒸发器的工作温度接近室外环境温度,而冷凝器的工作温度接近供暖区域的温度。 众所周知,热泵空调器按热泵方式运行时,其烘热能力受环境温度的影响,环境温度越低,供热能力也越低。在环境温度低于－７℃时,其制热能力与标称能力相比将大大减少,制热效果难如人意。其主要原因…     

干湿球温度在国标允差内变化对风管送风式热泵性能影响的实验研究

为分析现行国标规定的干湿球温度允差对空调机组能效的影响,采用空气焓差性能测试方法,控制环境干湿球温度在GB/T 17758—2010规定的读数允差±1℃/±0.5℃内波动,测定风管送风式热泵实验样机的制冷量与能效比。实验结果表明,室内外侧干球温度达允差下限-1℃,室内外侧湿球温度达允差上限+0.5℃时,机组处于最佳制冷工况,EER为2.80,高于标准工况测量值达3.26%。室内侧湿球温度对EER影响最为显著,影响系数为0.0464;其次是室外侧干球温度,对EER的影响系数为-0.0340。将干湿球温度允差严格为±0.3℃/±0.1℃,EER测定误差将由±3.5%降低至±1%,可更准确评定机组的能效等级。     

空气源热泵自然冷源过冷制热性能实验研究

冬季我国北方室外环境蕴含大量天然冷源,热力学分析表明热泵工质过冷释放的热量可以在蒸发器的等温吸热过程中获得补偿。为了研究大气自然冷源对热泵制热性能的影响,增设室外过冷器,搭建利用自然冷源过冷的空气源热泵实验装置。实验结果表明：当室外环境温度大于0 ℃,冷凝温度小于45 ℃的条件下,自然冷源过冷对热泵制热量与制热COP影响均较小,系统制热量维持在6.22 ~ 6.70 kW,制热COP维持在3.03,压缩机排气温度维持在103 ℃以下;当室外环境温度小于 -10 ℃,冷凝温度大于50 ℃时,随过冷度的增加,压缩机功率增加、排气温度显著增高,系统制热量呈先缓慢增加后减小趋势,制热COP降至2.3。基于上述研究提出一种空气源热泵过冷融霜新型除霜方式,融霜同时不停止制热。     

冷凝器面积对空气源热泵制热性能的影响研究

目的 研究低温条件下空气源热泵的烘干性能。方法 论文主要采用焓差法研究在换热面积和室外温度(温度为7、−12、−20 ℃,相对湿度为65%)不同时,空气源热泵的制热量、输入功率、能效等性能。结果 在7 ℃环境中,增加室内侧换热器面积,热泵的制热量提高了19%,系统能效提升了14%,但输入功率增加了5%;在−12~−20 ℃环境中,增加室内侧换热器面积,热泵的制热量提升了5%,系统能效提升明显,最大可提升27%,输入功率最大降低为17%。结论 增加室内侧换热器面积,系统焓差降低,但是能提高系统在低温下的循环风量,制热性能更加优异。     

气泵驱动冷却机组在某小型数据中心的运行性能分析

为了将气泵驱动冷却机组更好地应用于数据中心,本文对自行设计的气泵驱动冷却机组在北京地区某小型数据中心的运行性能进行研究,通过监测其实际运行情况,分析了机组的工作特性,拟合出工作特性曲线。结果表明:机组换热量随室内外温差的增大而增大,当室内外温差为11℃时,换热量约为10.4 kW,室内外温差达到23℃时,换热量约为13.6 kW;气泵功率随室内外温差的增大而减小,当室内外温差为11、23℃时,气泵功率分别为1 300、810 W。当室外温度为-3.7℃,室内外温差为23℃时,机组EER可达10.40。当室外温度低于15℃时,采用此机组对数据中心机房进行散热能够满足室内负荷要求,与采用原空调散热相比全年节省电量6 842.24 kW·h,全年节能率约为25.78%。     

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.