空气源-水环热泵联合系统性能分析

建立空气源-水环热泵联合系统的模型,通过改变空气源-水环热泵联合系统的空气源热泵冷凝温度及蒸发温度,得到联合系统不同工况下的最佳性能系数。研究结果表明:在供水温度分别为45℃和50℃时,系统性能系数均在空气源热泵冷凝温度16℃时达到最大值,分别为2.128和1.954,供水温度为55℃时,系统性能系数在空气源热泵冷凝温度18℃时达到最大值1.805;供水温度分别为45℃,50℃和55℃时,单级系统(仅运行空气源热泵系统)、双级系统(空气源-水环热泵联合系统)相互切换的最佳蒸发温度分别为-2℃,-13℃和-23℃。指出根据不同工况及时调整热泵系统的运行方式能够提高系统能效。     

低温空气源热泵（冷水）机组名义工况的确定研究

对低环境温度空气源热泵(冷水)机组(简称低温热泵)标准中的名义制热工况确定问题进行了研究.通过对我国寒冷地区典型城市供热季节的室外干球温度及其对应湿球温度的分布进行统计分析,确定出低温热泵空气侧的名义制热工况条件为-12℃/-13.5℃;通过对典型房间分别采用风机盘管和辐射地板进行供热时,保证室内舒适性要求的空调末端出水温度的研究,给出了水侧的名义制热工况为回水温度38℃.上述结论可为商用和户用低环境温度空气源热泵(冷水)机组的标准制定提供参考.     

环境温度对空气源热泵供暖性能的影响及优化

本文计算分析了环境温度、出水温度和负荷平衡点对严寒地区典型城市(哈尔滨)低温空气源热泵供暖性能的影响及其经济性和节能减排效益。结果表明:相同出水温度下,机组输入功率随环境温度升高而降低,而机组能效与之相反;机组搭配地暖末端形式的年运行费用为30.74元/m~2,且与燃煤锅炉相比,供暖季可节约标准煤14.74 kg/m~2;不同负荷平衡点对热泵供暖系统的能效与经济性具有较大影响,对于所选典型城市哈尔滨而言最佳经济平衡点为-20℃。     

热回收效率对排风热回收式热泵性能的影响研究

排风热回收式热泵因具有结构紧凑,节能环保等优点,在北欧等国家得到一定的推广。排风热回收式热泵主要分为单级和双级热回收式热泵,而热回收装置作为双级热回收式热泵的重要部件,其热回收效率会影响到整个热泵系统的性能。通过TRNSYS对双级热回收式热泵在重庆冬季的运行情况进行了模拟,并与常规空气源热泵和单级热回收式热泵进行了对比。结果表明,双级热回收式热泵机组的性能系数随着热回收的效率升高而降低,且介于单级热回收式热泵和常规空气源热泵的性能系数之间,而双级热回收式热泵系统的性能系数则随热回收的效率升高而升高,在热回收效率为0.6的情况下,系统的性能系数为5.262,相较单级热回收式热泵和常规空气源热泵的性能系数,能效分别提升了31.29%和83.22%。     

吸收式热泵余热回收先进技术综述

热力发电厂余热资源丰富,且存在锅炉烟气排入大气环境导致的"白羽"现象。为此,国内外学者对烟气余热利用展开了大量研究,其中吸收式热泵作为余热驱动的能级提升装置被广泛应用于区域集中供热和供冷领域。针对目前余热回收领域中应用的回热、多效、多级和压缩-吸收复合的吸收式热泵技术进行综述,并提出一种由双级吸收热泵、升温型压缩吸收耦合热泵和三级烟气换热器组成的烟气余热全热回收系统。该系统基于烟气余热能量梯级利用原理,将烟气由145℃降为40℃以下,同时制取70℃以上的一次热网供暖热水,有效地提升能源利用效率,减少"白羽"现象的产生。     

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。     

低温环境下复叠式燃气机热泵的供热性能研究

为了提高燃气机热泵在低环境温度下的制热性能,本文将燃气机热泵技术与复叠式热泵技术相结合,提出了应用于低环境温度下的复叠式燃气机热泵（CGEHP）系统。使用MATLAB软件,建立了CGEHP数学模型。分析了燃气发动机转速、环境温度和系统进水温度对系统供热性能（总供热量、制热性能系数（COP）以及一次能源利用率（PER））的影响规律。结果表明：当环境温度分别为﹣20、﹣15和﹣10 ℃,以NH3-LiNO3作为吸收式热泵系统工质,发动机转速为1 500 r/min时,PER分别为1.0、1.02、1.04,比常规空气源电热泵系统分别提高了24%、15%、5%。     

空气源热泵地暖系统冬季应用

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93d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 kW,平均值6.71 kW;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。     

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。     

夏季冷热联供模式下的燃气机热泵机组性能分析

本文建立了一套以R134a为制冷剂工质、以天然气为一次能源驱动开启式压缩机做功的燃气机热泵系统,研究了当蒸发器进水温度为12～22℃,室外环境温度为24.2～35.6℃,发动机转速为1 400～2 000 r/min,夏季冷热联供模式时,空气源燃气机热泵(GEHP)机组的性能。结果表明:发动机转速和蒸发器进水温度的变化对系统性能的影响大于室外环境温度变化的影响。随着发动机转速由1 400 r/min增至2 000 r/min,系统COP_1、COP_2、PER_1、PER_2分别减小了15.5%、9.9%、18.8%、13.5%。在工况范围内,机组冷水出水温度可达6.7～19.3℃,热水出水温度可达40.7～61.7℃,考虑余热回收情况下系统PER_2可达1.14～1.45。     

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.     

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.     

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.……     

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.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.