IPLV和COP对冷水机组全年能耗的影响

分析ASHRAE90.1-2010对冷水机组的COP和IPLV限定值的要求,提出用IPLV值评估冷水机组全年能耗的局限性,建议在常规项目中冷水机组选型宜注重机组COP的比较,并兼顾机组的IPLV。     

空调温度不低于26℃的规定下对机组IPLV的探讨

介绍冷水(热泵)机组的综合部分负荷值IPLV的原理和分析,并根据我国规定空调温度不低于26℃的实际情况,提出对制定IPLV标准的建议。由于在IPLV原始定义和测量方法方面都来自美国,我国这方面的理论研究比较薄弱,并且IPLV与SEER的定义和测量方法上可能会产生交叉的碰撞,这里提出一些新的理解和建议,有必要加强这方面的基础研究。     

中美两国冷水机组标准的IPLV评价体系差异性分析

介绍中美两国冷水机组IPLV评价的现状,从IPLV的构建原理和权重系数的推导方法、试验工况、测试方法、测试允差、插值计算方法等方面对两国冷水机组IPLV评价体系进行对比分析,指出我国当前IPLV评价体系已不适应我国建筑业和暖通空调产业现阶段发展水平,该工作对于明确两国标准的差异性、推动我国冷水机组产品性能评价体系的改进与完善具有参考价值。     

季节能效比（SEER）与综合部分负荷值（IPLV）的一致性分析

季节能效比（SEER）和综合部分负荷值（IPLV）是近年来出现的制冷和热泵装置能源效率评价指标。对季节能效比（SEER）和综合部分负荷值（IPLV）的概念进行分析,从温度一小时数以及收益与付出比2个方面分析SEER与IPLV的一致性,计算不同地区、不同温度带下的SEER和IPLV值,得出不同的温度带对SEER和IPLV的影响趋于一致的结论。对这2项标准的一些关键概念所进行的阐述有助于对这2个标准的理解。     

对IPLV应用的探讨

认为用IPLV评估单机或系统全年能耗比满载设计点性能参数更具有客观性,IPLV应作为主机选型的主要依据。     

多联机室内机电子膨胀阀制冷剂内泄漏对制冷综合性能系数的影响

本文研究了多联机室内机电子膨胀阀(EEV)内泄漏对制冷综合部分负荷性能系数(IPLV)的影响。本文进行了两组实验研究,研究结果表明:第一组实验时,有一台室内机膨胀阀始终存在内泄漏,最终IPLV为4.53;第二组实验时,关闭的内机膨胀阀没有明显内泄漏,最终IPLV为4.72,比第一组数据提高了4.2%。从实验结果看出,部分负荷下不开机的室内机膨胀阀存在内泄漏,会导致测试的部分负荷制冷量下降,最终导致多联机IPLV降低。因此在进行多联机IPLV测试时需要关注室内机电子膨胀阀的内泄漏。     

变频多联制冷系统能效问题的探讨

从IPLV，EER／COP的工况条件和计算方法解释IPLV，EER／COP的区别，并用实际的数据阐述两者的差异。     

关于IPLV与冷水机组季节运行性能的讨论

通过对现行国家标准的研读,指出国家标准中IPLV计算和检测公式中2.3%,41.5%,46.1%和10.1%四个权重系数为国家标准确定值,不是工况测试结果,不能解读为变量。有关文献将IPLV作为评价冷水机组季节运行性能的重要指标,希望用IPLV评价冷水机组全年制冷运行能耗水平的观点缺乏设计标准和产品标准相关条款支持,笔者认为这种看法有待商榷。     

基于IPLV权重系数算法对冷水机组选型的探讨

通过对ARI550/590中IPLV权重系数的计算方法及对冷水机组部分负荷运行性能的介绍分析,提出了冷水机房IPLV的概念,并由此提出对冷水机组选型的讨论.     

综合部分负载能效值IPLV-真实反映冷水机组部分负载性能的参数

本文介绍了综合部分能效值IPLV的来源及演变的过程,并从建筑用空调和冷水机组的负载匹配的角度分析了用IPLV评价空调冷水机组部分负载能效的合理性.     

中国庐山地区大校场晚第四纪沉积年龄测定及层序地层学

通过庐山科学考察(1997—2009)对大校场沟口晚第四纪剖面地层进行精细研究,采用古地磁、电子自旋共振(ESR)、36Cl、释光法等多种仪器测年方法的分析,建立了完整剖面的全时段地层的自400 ka.B.P.以来的系列年龄数据,与之相对应识别出Biwa-III(320 ka.B.P.)事件、Biwa-II(260 ka.B.P.)事件、Biwa-I(180 ka.B.P.)事件(因铁盘扰动影响缺失)、Blake(100 ka.B.P.)事件、Laschamp(20 ka.B.P.)事件(因表层活动影响未发育)等古地磁极性事件,结合层序地层和层型特征及沉积环境将剖面地层由早至晚划分为4个发展旋回阶段:I阶段为冰期(400～200 ka.B.P.)气候时期,II阶段为间冰期(200～100 ka.B.P.)气候时期,III阶段为冰缘期(100～10 ka.B.P.)气候时期,IV阶段为冰后期(10～0 ka.B.P.)气候时期。     

Cyclodextrin inclusion complexes of miconazole and econazole--isolation, toxicity on human cells, and confirmation of a new interpretation of the drug supersaturation phenomenon

Parameters that influence the precipitation of the beta-cyclodextrin (beta-CD) inclusion complexes of the antimycotics miconazole and econazole were investigated. The mechanistic reason for the superior antimycotic activity of the miconazole inclusion complex was studied. The toxicity of the complex was estimated. The temperature, the buffer strength, and the effect of the addition of hydrotropic agents on the CD solubility diagrams for the antimycotics were estimated. The miconazole and the CD dissolution rate for the complex was measured. The hemolytic activity of the miconazole inclusion complex, the physical mixture, miconazole, and the nitrate salt were compared. The toxicity on TR146 oral cell layers was measured. Lowering the temperature meant that both complexes precipitated at lower CD concentrations. Addition of hydrotropic agents and variation of the buffer strength affected the solubility diagrams. The dissolution medium was supersaturated with miconazole. The supersaturation was not disclosed by the traditional method to analyze for drug supersaturation. The miconazole complex was more toxic to erythrocytes than the physical mixture. On the other hand, the toxic effects of the two products on the TR146 cell layers were similar. Lowering the temperature eased the isolation of genuine CD inclusion complexes of miconazole and econazole. The miconazole supersaturation is likely to be the reason for the superior antimycotic activity of the complex. The complex and the physical mixture had about the same toxicity on TR146 cell layers.     

On the effective constitutive properties of a thin adhesive layer loaded in peel

An experimental method to determine the complete stress-elongation relation for a structural adhesive loaded in peel is presented. Experiments are performed on the double cantilever beam specimen, which facilitates a more stable experimental set-up as compared with conventional methods like the butt-joint test. The method is based on the concept of equilibrium of the energetic forces acting on the specimen. Two sources of energetic forces are identified: the start of the adhesive layer and the positions of the two acting loads. By use of the concept of equilibrium of energetic forces, it is possible to measure the energy release rate of the adhesive layer instantaneously during an experiment. The complete stress-elongation relation is found to be the derivative of the energy release rate with respect to the elongation of the adhesive layer at its start. By this procedure, an effective property of the adhesive layer is measured. That is, the fields are assumed to be constant through the thickness of the layer and only vary along the layer. To investigate the validity of this approach, experiments are performed on five different groups of specimens with different dimensions. This leads to large variations in the length of the damage zone at the start of the adhesive layer. Four of the experimental groups are used to determine the stress-elongation relation. This is found to be independent of the geometry. For the remaining experimental group, the adherends deform plastically and simulations are performed with the stress-elongation relation determined from the four elastic groups. It is found that the relation cannot be used to accurately predict the behaviour of the experiments where the adherends deform plastically. This indicates that the stress-elongation relation has limited applicability.     

Modelling experimental bond fatigue failures of concrete beams strengthened with NSM CFRP rods

Near surface mounting (NSM) is a promising strengthening technique provided that the full bond between the strengthening material and the existing structure develops. Wahab et al. (2011) reported fatigue bond failures by de-bonding between the CFRP rod and the epoxy that started at mid span. As the load was cycled, the de-bonding propagated towards the support. The model presented here describes the failure of those beams. The de-bonding was modeled as a crack growing at the interface between the CFRP rod and the epoxy where the driving force was the interfacial shear stresses between the CFRP rod and the epoxy. Once the stresses at the crack tip exceeded the allowable fatigue stresses between the CFRP rod and the epoxy, de-bonding occurred and the crack length increased. Ahead of the crack tip, the CFRP rod was fully bonded to the epoxy and the forces decayed exponentially. Behind the crack tip, the rod was partially de-bonded. The experimental and calculated number of cycles until excessive slipping between the CFRP rod and the epoxy occurred and the forces in the CFRP rod at all locations in the shear span at the onset of failure were in good agreement.     

Transient three dimensional finite element analysis of a bird striking a fan blade

A comprehensive three-dimensional nonlinear finite element analyses were carried out to examine the effects of the geometry and the incidence angle of canonical 4-lb bird striking a stationary fan blade using LS-DYNA. Three aspects of the work were accordingly examined. The first was concerned with the modeling framework used. The second with the constitutive law that governs the behaviour of the bird. The third was concerned with the influence of the geometry and the angle of incidence of the bird on the integrity of the blade. This article combines and extends the earlier works on both the Lagrangian modeling methodology (Mao et al. AIAA J. Aircr. 44(2), 583–596, 2007) and the bird geometry studies (Meguid et al. 2008) in systematic and integrated manner. Both the bird and the blade were simulated in a Lagrangian framework. Furthermore, the homogenized fluidic constitutive equation of the bird follows the Brockman hydrodynamic model, while the blade is modeled as a viscoplastic material of the Perzyna type. The study focused on the three most-frequently used configurations in the literature; namely, hemispherical-ended cylinder, straight-ended cylinder, and ellipsoid, at various length-to-diameter aspect ratios. The results show that the initial contact area between the bird and target in the early phase of the impact event would have a significant effect on the peak impact force. Normal incidence results in maximum impact forces and plastic strains leading to severe deformation. For the case where the incidence angle is equal to or larger than 60°, the impact forces are significantly reduced and the blade deformation remains within the elastic range. The maximum impact force and the resulting plastic strain are not merely governed by the size of the bird but also its density.     

大型转子系统动力响应计算的谐波平衡—子结构方法

本文提出了一种计算大型转子—轴承—基础系统动力响应的新方法。该方法的主要特点是既适用于线性支撑的情况。也适用于非线性支撑的情况,轴承的动态特性参数不参加为缩减系统的自由度而进行的模态参数计算,并且方法具有明确的物理意义。     

管式预粘合纸箱结构参数与抗压强度的相关关系

目的研究管式预粘合纸箱结构参数与抗压强度的相关关系,为优化纸箱结构设计以及提高其抗压强度提供依据。方法首先设计普通、四棱台、花形锁等3种代表性管式预粘合纸箱,进而确定3种纸箱影响抗压强度的关键结构参数。其次将各结构参数依次作为自变量,其余结构参数作为常量,利用纸箱抗压试验机进行空箱抗压试验,记录各自的最大压溃力。最后对实验数据进行分析,明确抗压强度与结构参数间的相关关系。结果 3种纸箱的抗压强度均随着周长的增大而增大,其抗压强度并非全部随高度的增大而降低。考虑周长因素时,普通箱的抗压强度最佳;考虑高度因素时,花形锁箱的抗压强度最佳;考虑箱型因素时,当普通箱长宽比接近1.0,四棱台箱下上底比在1.2~1.4范围内,花形锁箱的啮合点和花形锁圆心的连线与水平线所成夹角接近30°时,抗压强度最佳。因结构参数的影响,管式预粘合纸箱的抗压强度整体上显著优于标准开槽纸箱。结论预粘合纸箱的关键结构参数对其抗压强度有显著影响,在设计时应给予足够的重视。     

注塑充模聚合物流动形态与力学行为分子机制研究

以聚甲基丙烯酸甲酯(Polymeric methyl methaerylate,PMMA)为实验材料,基于分子动力学模拟实验研究了注塑成型聚合物充模流动与力学行为的分子机制.构建包含10条聚合度为20的无规PMMA分子链所构成的链团模型,基于能量最小化与SA算法实现了体系能量初始化;基于周期性边界,引入COMPASS从头算分子力场及Velocity-Verlet算法,实现了PMMA胞元在恒温平面流场中的流态与力学行为模拟实验.结果表明,PMMA充模与形变过程首先需要克服包含体系内能、分子链松弛与解缠在内的“活化能”,且存在时间和应力阈值,前者体现了瞬时加载内能协调效应,后者对应于高剪切力作用下分子松弛与解缠现象.体系C原子回转半径分布表明剪切力的作用使得高分子沿流场方向取向排布,剪切力越大则取向越明显,剪切力过大则分子链将断裂而弹性恢复.MSD结果揭示了熔态聚合物充模流动的实质是大分子链定向迁移和取向排布协调运动的结果,且进一步验证了“活化能”的存在,克服这一制约之后大分子链的迁移效应才变得明显,且迁移速率随剪切应力的增大呈非线性增大变化.     

On the effect of the residual stresses on the crack opening displacement in a cracked sheet

The residual stress and displacement fields caused by localized plastic flow near a mode I crack tip in a sheet under plane stress conditions are investigated. The present study founds on the classical Dugdale scheme of the plastic flow localization. The residual stress field is considered to be induced by reversed plastic flow near the crack tip caused by an unloading. As it is found the residual stresses around the crack compress the crack tip, while the residual tensile stresses in a distant from the crack tip zone occur. It is shown the maximum residual tensile stresses can reach the significant value of the one third of the yield limit. The length of the compressed plastic zone and the residual displacement distributions are obtained. The exact formula for the residual crack opening displacement to estimate the crack closure is found. Then the next loading of the cracked plate is considered. It is shown that the second loading causes the origin of two plastic zones localized near the crack tip and at the point, where the maximum residual tensile stresses are concentrated. Again, according to the Dugdale scheme of the plastic localization, both the plastic flow zones are modelled as narrow stripes on the line extending the crack. To determine three non-dimensional parameters, characterizing the position of the segment-like plastic flow zones, a non-linear system of equations is obtained and analyzed. The exact formula for the crack opening displacement after a loading–unloading cycle is obtained. An asymptotic analysis (as the linear dimension of the distant plastic flow zone compared with the actual crack length is small) is given. It shows that the effect of the distant plastic flow zone appears as some complementary crack closure.     

原油含水率检测线圈传感器的优化

为了提高电磁电导法管外测量原油含水率线圈传感器的灵敏度,对影响灵敏度的关键参数--线圈传 感器的距离进行了优化设计。在保持最优频率和电流强度不变的情况下,首先,使用ANSYS进行电磁仿真,通过比较发射线圈和屏蔽线圈在管道内部产生的磁场强度大小确定了两线圈之间的最优距离为0.6 m;然后,利用 MATLAB从0. 1 m到1 m对接收线圈上的电压进行了数据计算,结果表明0. 6 m处的电压值最大,最优距离使原油 含水率的有用信号从0.1 m或1 m的0.03 μV提高到了0.6m的1.27 μV,使传感器的灵敏度提高了41倍;最后, 实际测试了两线圈距离从0.1 m至1 m接收线圈上多点电压值,实验结果表明0. 6 m处的电压值最大,进一步证明了 0. 6 m为两个线圈间的最优距离。