非共沸环保制冷剂的特点和应用技术

环保制冷剂有很多是非共沸的,如R407C和R417A,这些制冷剂与常规制冷剂有不同特点.本文将分析研究非共沸制冷剂在系统的设计、调试、运行和维修中的难点,为制冷系统的安全、可靠和高效的运行提供技术支撑.     

全面科学地实施对制冷剂的管制

本文给出了鉴别目前的制冷剂用户以及他们的设备能否影响未来制冷剂选择方案的一些方法.从最近对工业界征收特别税的一些科学评价来看,制冷剂的未来是充满着挑战.作者以这种客观的评论态度,作了一一报导,并为作出明智的决定和防止可能太草率的淘汰提出了三点建议.     

单元式空调机应用混合制冷剂的课题

以混合制冷剂代替单元式空调制冷系统普遍使用的Ｒ２２，是空调设备技术发展的重要趋势。本文介绍了Ｒ４０７Ｃ和Ｒ４１０Ａ两种混合制冷剂的基本特性、使用混合制冷剂所涉及的有关技术监督管理法规及相应的标准、安全性、热力性能等技术课题。     

我国空调用制冷剂回收再生的机遇与挑战

中国是全世界最大的制冷设备与制冷剂生产国和消费国,全球制冷剂超过1/3的需求量来自中国。预计至2030年,我国制冷空调行业制冷剂消费总量将达15.4~17.8万吨。本文介绍了国内外制冷剂回收再生技术及设备现状;调研了国内外对于制冷剂回收、净化再利用的相关标准,以及制冷剂中不同污染物含量的检测方法;分析了常用的传统制冷剂碳排放评价指标及优缺点,探讨了一种适合制冷剂回收再生过程的制冷剂气候性能评估指标;提出制冷剂回收、净化再利用的机遇与挑战。     

春兰环保空调已成功突围欧盟制冷剂专利

前不久，霍尼韦尔（中国）有限公司将涉嫌侵犯其空调用无氟制冷剂R410A知识产权的一家中国制冷剂生产企业告上法庭，并获得了一审胜诉，致使该企业经济损失约25万欧元。该公司表示，将持续加大对侵犯其专利权的国内空调出口企业的追责力度。     

美国艾默生公司压缩机应用技术讲座——第十八讲 R41OA空调制冷剂的特点

本文是有关介绍新型制冷剂专题的系列文章之二。第一篇文章回顾了R410A的发展史，介绍了R410A如何成为空调系统的新宠。本文将比较不同制冷剂的特性，并解释了全球越来越多的空调生产商倾向选择R410A的原因是在系统成本允许的条件下，他们不仅需要使效率更高，还要肩负环境保护的责任。上一篇文章阐述过，R22曾经是世界上使用最广泛的碳氟化合物制冷剂，而目前已出现了数种用以取代R22的候补产品，包括环保的含氢氟代烃（HFC）制冷剂-R134a，R410A和R407C。     

R22、R404A与R407F制冷剂压缩机性能对比

分析R22、R404A与R407F制冷剂的物理性质,并采用涡旋压缩机进行试验测试。结果表明:在高温应用上,R22、R404A和R407F制冷能力数值相近,R407F制冷系数比R22、R404A稍低;而在低温应用上,R407F制冷能力、制冷系数比R22、R404A都低。     

R407C、R410A系统热力性能研究综述

本文介绍了R22制冷剂最有希望的替代物R407C和R410A的基本物性，以及国外学者对使用这两种工质的制冷系统有关换热、压降特性及对COP影响的研究成果，以帮助国内制冷、空调企业了解R22替代工质研究的新动向、加快制冷工质替代的步伐。     

冷冻冷藏用制冷剂R404A的替代品对比分析

基于现有的R404A涡旋式压缩机,模拟分别采用R404A,R407A,R407F,R134a和R1234ze制冷剂时的压缩机性能,计算5种制冷剂系统的理论循环COP,并对各典型工况进行对比分析。计算结果表明,R407A和R407F可直接应用于R404A压缩机,而R134a和R1234ze替代R404A时压缩机设计变更较大,4种制冷剂系统能效均较R404A系统有较大提高。     

R410A制冷剂用冷冻机油的研制

选择与制冷剂R410A相溶性良好的酯类合成基础油,通过对功能添加剂的筛选,确定配方体系,研制出具有较好抗氧化性、抗磨性和抗水解安定性的酯类合成冷冻机油,最后通过压缩机台架评定试验验证,该合成冷冻机油能够满足R410A制冷剂压缩机的工况要求。     

Surface Tension of HFC Refrigerant Mixtures

The surface tension of refrigerant mixtures, i.e., R-410A (50 mass% R-32/50 mass% R-125), R-410B (45 mass% R-32/55 mass% R-125), R-407C (23 mass% R-32/25 mass% R-125/52 mass% R-134a), R-404A (44 mass% R-125/52 mass% R-143a/4 mass% R-134a), and R-507 (50 mass% R-125/50 mass% R-143a), has been measured and correlated in the present study. Although the first three mixtures are very important as promising replacements for R-22 in air-conditioners and heat-pumps and the last two are promising replacements for R-502, surface tension data for these mixtures were not previously available. The measurements were conducted under conditions of coexistence of the sample liquid and its saturated vapor in equilibrium. The differential capillary rise method (DCRM) was used, with two glass capillaries with inner radii of 0.3034±0.0002 and 0.5717±0.0002 mm. The temperature range covered was from 273 to 323 K, and the uncertainty of measurements for surface tensions and temperatures is estimated to be at most ±0.2 mN·m^–1 and ±20 mK, respectively. A mixing rule was selected for representing the temperature dependence of the resultant data. These data were successfully represented by a mixing rule using mass fraction based on the van der Waals correlation.     

HFC-161及其应用

介绍ODs替代品HFC-161的性质及应用实例，通过分析与实验说明这些混合制冷剂能够分别替代R410A，R407C，R404A和HFC-134a，均具有环保性能优异、能效比高、用量少、与原系统兼容等特点。     

Comparison of experimental pressure drop data for two phase flows to prediction methods using a general model

In this paper, existing and new two phase pressure drop data are used to run an extensive comparison to predictive methods. The database used is for seven refrigerants (R22, R134a, R404A, R407C, R410A, R417A, and R507A) over a wide range of operating conditions. The procedure used for the comparison is a model of general validity since it is independent of the data reduction procedure. Four quoted methods and a new one by Moreno Quibén and Thome are used. The statistical analysis showed that the methods by Grönnerud and by Moreno Quibén and Thome are equally the best. Segregating the data by flow regimes and taking into account for the prediction of the data trends, the method by Moreno Quibén and Thome is able to give reliable predictions in all the range of vapour qualities, especially in the regions of the intermittent flow and dry-out.     

Viscosity of Gaseous R404A, R407C, R410A, and R507

This paper presents new measurements of the viscosity of gaseous R404A (52 wt% R143a, 44 wt% R125, 4 wt% R134a), R407C (23 wt% R32, 25 wt% R125, 52 wt% R143a), R410A (50 wt% R32, 50 wt% R125), and R507 (50 wt% R143a, 50 wt% R125). These mixtures are recommended as substitutes for the refrigerants R22, R502, and R13B1. Measurements were carried out in an oscillating-disk viscometer. The obtained values of the viscosity are relative to the viscosity of nitrogen. The experiments were performed at atmospheric pressure over the temperature range 297 to 403 K. and near the saturation line up to pressures of 0.6 P _crit. The estimated uncertainty of the reported viscosities are ±0.5% for the viscosities at atmospheric pressure and ± 1% along the saturation line, being limited by the accuracy of the available vapor pressure and density data. The experimental viscosities at atmospheric pressure are employed to determine the intermolecular potential parameters, and , which provide the optimum representation of the data with the aid of the extended law of corresponding states developed by Kestin et al. A comparison of the experimental viscosity data with the values calculated by REFPROP, both at atmospheric pressure and along the saturation line, is presented.     

Pseudo-Pure Fluid Equations of State for the Refrigerant Blends R-410A, R-404A, R-507A, and R-407C

Pseudo-pure fluid equations of state explicit in Helmholtz energy have been developed to permit rapid calculation of the thermodynamic properties of the refrigerant blends R-410A, R-404A, R-507A, and R-407C. The equations were fitted to values calculated from a mixture model developed in previous work for mixtures of R-32, R-125, R-134a, and R-143a. The equations may be used to calculate the single-phase thermodynamic properties of the blends; dew and bubble point properties are calculated with the aid of additional ancillary equations for the saturation pressures. Differences between calculations from the pseudo-pure fluid equations and the full mixture model are on average 0.01%, with all calculations less than 0.1% in density except in the critical region. For the heat capacity and speed of sound, differences are on average 0.1% with maximum differences of 0.5%. Generally, these differences are consistent with the accuracy of available experimental data for the mixtures, and comparisons are given to selected experimental values to verify accuracy estimates. The equations are valid from 200 to 450 K and can be extrapolated to higher temperatures. Computations from the new equations are up to 100 times faster for phase equilibria at a given temperature and 5 times faster for single-phase state points given input conditions of temperature and pressure.     

Formation Conditions of Clathrates Between HFC Alternative Refrigerants and Water

There are two promising candidates as alternative refrigerants for air-conditioners and heat pumps. The first is R407C, which is composed of HFC-32 (23 mass%), HFC-125 (25 mass%), and HFC-134a (52 mass%). The second is R410A, which is composed of HFC-32 (50 mass%) and HFC-125 (50 mass%). In this study, formation conditions of clathrate compounds between water and HFC alternative refrigerants such as HFC-32, HFC-125, HFC-134a, and their mixtures, R407C and R410A, were investigated. Phase diagrams of clathrates of these HFC alternative refrigerants and their mixtures were determined. From the phase diagrams, the critical decomposition temperature and the critical decomposition pressure were determined. The relationship between the critical decomposition points for the clathrates of HFC-32, HFC-125, HFC-134a, R410A, and R407C were studied. It is found that R407C and R410A form clathrate compounds with water under the evaporating temperature condition in the refrigeration cycle of air-conditioners and heat pumps.     

Thermal Conductivity of the Refrigerant Mixtures R404A, R407C, R410A, and R507A

New thermal conductivity data of the refrigerant mixtures R404A, R407C, R410A, and R507C are presented. For all these refrigerants, the thermal conductivity was measured in the vapor phase at atmospheric pressure over a temperature range from 250 to 400 K and also at moderate pressures. A modified steady-state hot-wire method was used for these measurements. The cumulative correction for end effects, eccentricity of the wire, and radiation heat transfer did not exceed 2%. Calculated uncertainties in experimental thermal conductivity are, in general, less than ±1.5%. All available literature thermal conductivity data for R404A, R407C, R410A, and R507C were evaluated to identify the most accurate data on which to base the thermal conductivity model. The thermal conductivity is modeled with the residual concept. In this representation, the thermal conductivity was composed of two contributions: a dilute gas term which is a function only of temperature and a residual term which is a function only of density. The models cover a wide range of conditions except for the region of the thermal conductivity critical enhancement. The resulting correlations are applicable for the thermal conductivity of dilute gas, superheated vapor, and saturated liquid and vapor far away from the critical point. Comparisons are made for all available literature data.     

Vapor–Liquid Critical Surface of Ternary Difluoromethane+Pentafluoroethane+1,1,1,2-Tetrafluoroethane (R-32/125/134a) Mixtures

The plane of vapor–liquid criticality for ternary refrigerant mixtures of difluoromethane (R-32)+pentafluoroethane (R-125)+1,1,1,2-tetrafluoroethane (R-134a) was determined from data on the vapor–liquid coexistence curve near the mixture critical points. The compositions (mass percentage) of the mixtures studied were 23% R-32+25% R-125+52% R-134a (R-407C), 25% R-32+15% R-125+60% R-134a (R-407E), and 20% R-32+40% R-125+40% R-134a (R-407A). The critical temperature of each mixture was determined by observation of the disappearance of the meniscus. The critical density of each mixture was determined on the basis of meniscus disappearance level and the intensity of the critical opalescence. The uncertainties of the temperature, density, and composition measurements are estimated as ±10 mK, ±5 kg·m^–3, and ±0.05%, respectively. In addition, predictive methods for the critical parameters of R-32/125/134a mixtures are discussed.     

R404A和R410A应用于平行流冷凝器的模拟分析比较

采用分布参数法对平行流冷凝器建立数学模型，对目前广泛使用的制冷剂R134a和低温制冷剂R404A和R410A在平行流冷凝器中的换热和流动性能进行模拟计算和分析比较。分别在相同和不同工况下。比较3种制冷剂的换热系数及压降等换热和流动性能参数。结果表明，在采用平行流冷凝器的汽车空调工况范围内，R410AR404A的流动和传热性能均优于R134a，更适宜用于汽车空调用平行流冷凝器。     

R404A和R407C在水平强化管外的凝结换热实验研究

实验研究了近共沸制冷工质R404A与非共沸制冷工质R407C在水平强化换热管管外的凝结换热性能。采用"Wilson图解法"对实验数据进行处理。结果表明:对于R404A和R407C,强化管外的凝结换热系数随着壁面过冷度的增加而增大,呈现出与纯工质冷凝时不同的变化趋势,这主要是近共沸或非共沸工质凝结过程中,某些组分的凝结会遇到其它组分的凝结气膜热阻所造成的;随着过冷度增加,易挥发组分开始凝结,气膜变薄,冷凝传热系数增大。R407C在强化换热管管外的凝结换热系数比R404A要小70%左右,这是由于R407C的温度滑移较R404A要大,管外形成的凝结扩散气膜造成的影响更大。R407C在高热流密度工况下的换热效果提升明显,故应尽量工作在高热流密度区域。