冰箱制冷剂的最佳充注量计算

一、现有计算法我国拥有数以百万计的家用和厨房用冰箱,在产品设计制造和维修中都有一个给冰箱加注多少制冷剂的问题。众所周知,制冷剂加入量过多和过少,对于冰箱的运行都是不利的。但制冷剂注入量的精确计算,迄今     

二甲醚作为冰箱制冷剂的理论分析

对二甲醚（DME）用作冰箱制冷剂进行理论分析，比较制冷剂DME与冰箱制冷剂HFC134a和HC600a的基础热物理性质。对它们的冰箱标准工况制冷循环性能和变工况制冷循环性能进行理论计算及分析。分析表明：制冷剂DME的制冷性能与HFC134a和HC600a的制冷性能基本相似，性能系数（COP）却优于HFC134a和HC600a。并且，二甲醚具有环保、无毒和与材料兼容的特点。因此，二甲醚适合做新一代的冰箱制冷剂。     

二氧化碳冰箱一举两得

电冰箱的问世堪称为 2 0世纪改变人类生活方式的重大发明之一。但 90年代以前生产的冰箱其制冷剂主要是“氯氟碳”。一旦从压缩机中泄漏 ,可直上云霄甚至破坏夸大气臭氧层形成空洞 ,最终导致皮肤癌发病率剧增。 90年代 ,中国外开发使用的“绿色制冷剂”主要是“氢氯氟碳”与“氢氟碳”,但它们一旦泄漏同样会造成大气环境变化。日本一家电器公司的工程技术人员试用地球上取之不尽、用之不竭的二氧化碳气体作为新颖冰箱制冷剂。二氧化碳经压缩机压缩后同样会变成液体 ,故可用于各种类型的电冰箱中 ,二氧化碳作为冰箱制冷剂在压缩成液体的过程…     

冰箱压缩机制冷量测量方法的选择

制冷量是冰箱压缩机的一个重要参数。它的测量方法很多,当前在国内是广泛采用第二制冷剂量热法来测量的。由于在采用第二制冷剂量热法时,必须设计一个密闭的耐压绝热容器。要做到这一点不是那么容易的,     

THR01绿色冰箱的研究与生产

本文报导了采用ＴＨＲ０１混合工质的冰箱研究结果。ＴＨＲ０１是一种亚共沸混合制冷剂，其性能Ｑｏ，Ｑｕ，ＣＯＰ，只，Ｐｅ均较接近ＣＦＣ１２。可作为过渡替代制冷剂。按ＡＳＴＭ－６１８—８４标准，进行的可燃性试验证明其安全可靠。在ＣＦＣ—１２冰箱所有主要部件不作改变时，用该制冷剂充灌的各种型号冰箱，多年来试验证明可节能５—１０％左右。１９９５年以来沈阳电冰箱厂应用ＴＨＲ０１制冷剂的ＢＣＤ—２１８冰箱已生产了６５０００台并取得国家环保标志。     

三氟甲醚作为冰箱制冷剂的理论分析

对氟化醚类工质三氟甲醚(简称HFE143a)用作冰箱制冷剂进行了全面的理论分析。首先比较了新制冷剂HFEl43a和冰箱制冷CFCl2、HFCl34a和HFCl53a／HCFC22等的基础热物理性质。然后对它们的的冰箱标准工况制冷循环性能和变工况制冷循环性能进行了详细的理论计算及分析。分析表明：适应更高环境保护要求的HFC143a完全适合做新一代冰箱制冷剂。     

冰箱中制冷剂R134a和碳氢化合物替代R12的研究

本文主要进行了冰箱中制冷剂替代物R134_a、R290、R600a与R12的分析比较,指出了其优缺点,并进行了理论计算,为冰箱中制冷剂替代物的选择提供了理论依据。     

冰箱的节能与CFCs替代

冰箱耗电量较大，研制节能型冰箱具有重要意义。另外，目前冰箱中使用的制冷剂ＣＦＣ１２不久将被禁用，替代物研究是十分迫切的任务。这也可在研制节能冰箱时与ＣＦＣｓ替代联系起来。本文综述了目前正在研究或已经使用的冰箱节能措施与ＣＦＣ５替代，有利于制订出我国的产品发展方向。     

制冷剂管道参数对冰箱振动影响特性

为减小冰箱振动、降低噪声,利用Pro/Engineer软件分别建立冰箱制冷剂管道内部气柱及管道三维实体模型,用有限元分析软件ANSYS分析模态,获得气柱及管道固有频率。气柱固有频率与压缩机激发频率相差较大不会产生共振,而管道固有频率在共振区内会产生共振。在制冷剂管道材料不变条件下分析不同管道长度、弯管圆角半径及固定支撑位置对冰箱振动特性影响。结果表明,减小制冷剂管道长度会增大固有频率并逐渐远离共振区,从而避免管道共振;增加制冷剂管道弯管圆角半径,其固有频率略有增大,一阶固有频率仍在共振区内导致管道共振;在制冷剂管道不同位置增加固定支撑,能有效提高管道固有频率,使其远离共振区,且存在最佳安装位置。     

论扩散-吸收式冰箱热虹吸泵对制冷系统的影响

扩散-吸收式冰箱是利用加热实现制冷。其使制冷剂循环的设备是热虹吸泵，本文分析热虹吸泵的热负荷及结构尺寸与冰箱制冷量之间的关系，为扩散-吸收式冰箱的制造提供理论依据。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。