Measurements of the viscosity of R11, R12, R141b,and R152a in the temperature range 270–340 K at pressures up to 20 MPa

This paper reports new measurements of the liquid viscosity of R11, R12, R1416, and R152a in the temperature range 270 to 340 K and pressures up to 20 MPa. The measurements have been carried out in a vibrating-wire instrument calibrated with respect to the standard reference value of the viscosity of water. It is estimated that the uncertainty of the present viscosity data is one of 0.5%. The experimental data have been represented by polynomial functions of temperature and pressure for the purposes of interpolation. A recently developed semiempirical scheme, based on considerations of hard-sphere theory, is employed to correlate successfully the viscosity and the thermal conductivity of these refrigerants as a function of their density.     

Measurements of the viscosity of R134a and R32 in the temperature range 270–340 K at pressures up to 20 MPa

This paper reports new measurements of the liquid viscosity of R134a and R32 in the temperature range 270 to 340 K and pressures up to 20 MPa. The measurements have been carried out in a vibrating-wire instrument calibrated with respect to the standard reference value of the viscosity of water. It is estimated that the uncertainty of the present viscosity data is one of 0.5%. The experimental data have been represented by polynomial functions of temperature and pressure for the purposes of interpolation.     

The viscosity of liquid R134a

The paper reports new measurements of the viscosity of liquid R134a over the temperature range 235 to 343 K and pressures up to 50 MPa. The measurements have been carried out in a vibrating-wire viscometer calibrated with respect to the viscosity of several liquid hydrocarbons. It is estimated that the uncertainty in the viscosity data reported is ±0.6%. The data therefore have a lower uncertainty than that of earlier measurements of the viscosity of this environmentally acceptable regrigerant. The viscosity data have been represented as a function of density by means of a formulation based upon the rigid, hard-sphere theory of dense fluids with a maximum deviation of ±0.3%. This representation allows the present body of experimental data to be extended to regions of thermodynamic state not covered by the measurements.     

Thermophysical Properties of 1,1,1,3,3-Pentafluorobutane (R365mfc)

This paper presents an experimental study on various thermophysical properties of a new fluoroalkane, 1,1,1,3,3-pentafluorobutane (R365mfc). The thermal conductivity of R365mfc was measured in the liquid phase near saturation conditions at temperatures between 263 and 333 K using a parallel plate instrument with an uncertainty of less than ±5%. For the measurement of the saturated liquid density between 273 and 353 K, a vibrating tube instrument was used. The uncertainty of the density measurements is less than ±0.1%. In addition, experimental data have been obtained for R365mfc under saturation conditions over a wide temperature range from about 253 to 460 K using light scattering techniques. Light scattering from the bulk fluid has been applied for measuring both the thermal diffusivity and the sound speed in the liquid and vapor phases. Light scattering by surface waves on a horizontal liquid–vapor interface has been used for the simultaneous determination of the surface tension and kinematic viscosity of the liquid phase. With the light scattering techniques, uncertainties of less than ±1.0, ±0.5, ±1.0, and ±1.2% have been achieved for the thermal diffusivity, the sound speed, the kinematic viscosity, and the surface tension, respectively.     

Thermal conductivity of the new refrigerants R134a,R152a,and R123 measured by the transient hot-wire method

Thermal-conductivity measurements are reported for the new refrigerants R134a, R152a und R123. Transient hot-wire experiments were performed which cover both the liquid and vapor states at temperatures and pressures ranging from?=?20°C to 90°C and fromp=0.1 bar to 60 bar respectively. The results are correlated with density and temperature. In addition temperature dependent correlations are presented for (i) saturated liquid, (ii) saturated vapor, (iii) ideal gas (which equals approximately vapor state at ambient pressure). Finally the results are compared with data from the literature and also with the thermal conductivities of R12 and R11.     

Measurements of the thermal conductivity of liquid R32, R124, R125, and R141b

This paper reports measurements of the thermal conductivity of refrigerants R32, R124, R125, and R141b in the liquid phase. The measurements, covering a temperature range from 253 to 334 K and pressure up to 20 MPa, have been performed in a transient hotwire instrument employing two anodized tantalum wires. The uncertainty of the present thermal-conductivity data is estimated to be ±0.5%. The experimental data have been represented by polynomial functions of temperature and pressure for the purposes of interpolation. A comparison with other recent measurements is also included.     

Thermophysical Properties of the Refrigerant Mixtures R410A and R407C from Dynamic Light Scattering (DLS)

Dynamic light scattering (DLS) has been used for the measurement of several thermophysical properties of the refrigerant mixtures R410A and R407C. Thermal diffusivity and sound speed have been obtained by light scattering from bulk fluids for both the liquid and vapor phases under saturation conditions over a temperature range from about 290 K up to the liquid-vapor critical point. By applying the method of DLS to a liquid-vapor interface, also called surface light scattering (SLS), the saturated liquid kinematic viscosity and surface tension can be determined simultaneously. These properties have been measured for R410A and R407C from about 240 to 330 K and 240 to 350 K, respectively. The results are discussed in detail in comparison with literature data and with a simple prediction method based on the mass-weighted properties of the pure components expressed as functions of the reduced temperature.     

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.     

Viscosity of R134a, R32, And R125 at Saturation

This paper reports the results of the measurement of the viscosity of R134a close to the saturation line in the vapor phase. The new measurements were carried out in a vibrating-wire viscometer specially constructed for the purpose, and the results have an accuracy of ±2%. In addition, the opportunity is taken to present a reevaluation of earlier measurements along the saturation line of the viscosity of R32 and R125. Improved equations of state for these fluids are now available and can be employed to generate improved values for the viscosity.     

Viscosity Measurements of Ammonia, R32, and R134a. Vapor Buoyancy and Radial Acceleration in Capillary Viscometers

The saturated liquid viscosity of ammonia (NH₃) and of the hydrofluorocarbons, difluoromethane (CH₂F₂, R32) and 1,1,1,2-tetrafluoroethane (CF₃–CH₂F, R134a), was measured in a sealed gravitational viscometer with a straight vertical capillary. The combined temperature range was from 250 to 350 K. The estimated uncertainty of the ammonia measurements is ±3.3 and ±2 to 2.4% for the hydrofluorocarbons with a coverage factor of two. The results are compared with literature data which have been measured with capillary viscometers of different design. Agreement within the combined experimental uncertainty is achieved when some of the literature data sets are corrected for the vapor buoyancy effect and when a revised radial acceleration correction is applied to data which were obtained in viscometers with coiled capillaries. An improved correction for the radial acceleration is proposed. It is necessary to extend inter-national viscometry standards to sealed gravitational capillary instruments because the apparent inconsistencies between refrigerant viscosity data from different laboratories cannot be explained by contaminated samples.     

Viscosity of saturated R152a measured with a vibrating wire viscometer

Earlier reported values of the viscosity coefficient of the refrigerant R152a (1,1-difluoroethane) have been recalculated with an improved value for the mechanical damping of the vibrating wire viscometer. The measurements were taken along the saturation line both in the saturated liquid and in the saturated vapor every 10 K from 243 up to 393 K by means of a vibrating wire viscometer The damping of the vibration of the wire is a measure for the viscosity provided that the mechanical damping is subtracted. The latter is usually measured in vacuum. It turns out that the damping value measured in this way depends on the vacuum pressure and on the way the wire has been handled before. It appeared that the damping applied previously, measured after 6 days of pumping, is too small, resulting in values of the viscosity coefficient which are too large. The effect on the data for the saturated-liquid viscosity is small, but the new saturated-vapor viscosity data agree much better with the unsaturated-vapor data reported by Takahashi et al.     

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.     

Thermal conductivities of new refrigerants R125 and R32 measured by the transient hot-wire method

Thermal conductivity measurements are reported for the new refrigerants pentafluoroethane (R125) and dilluoromethane (R32), which are suggested to replace chlorodifluoroethane (R22) as components of a mixture. Transient hot-wire experiments were performed which cover both the liquid and the vapor states at temperatures and pressures ranging fromt = –40 to 90°C and fromp = 1 to 60 bar. Uncertainties keep within 1.6% for liquid and 2.0% for vapor states, The results are correlated with density and temperature. In addition, temperature-dependent correlations are presented for practical calculations for (i) saturated liquid, (ii) saturated vapor, and (iii) dilute gas (which approximately equals the vapor state at ambient pressure). Finally, the results are compared with data from the literature and also with the respective thermal conductivities of R22.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Thermophysical properties of R143a (1,1,1-trifluoroethane)

Various thermophysical properties of refrigerant R143a (1,1,1-trifluoroethane) have been determined under saturation conditions using dynamic light scattering (DLS). Light scattering from bulk fluids was applied for measuring the thermal diffusivity and the sound velocity for both the saturated liquid and vapor phase over a wide temperature range of 273-346 K. The results were also used to obtain information on the specific heat at constant pressure and the isentropic compressibility. Furthermore, the surface tension and liquid kinematic viscosity were determined simultaneously in the temperature range 253-333 K from light scattering by surface waves on a horizontal liquid-vapor interface. All experiments are based on a heterodyne detection scheme and a signal analysis by photon correlation spectroscopy (PCS). The results for R143a are discussed in detail and compared to literature data available.     

Measurements of the thermal conductivity of R22, R123, and R134a in the temperature range 250–340 K at pressures up to 30 MPa

This paper reports new, absolute measurements of the thermal conductivity of the liquid refrigerants R22, R123, and R134a in the temperature range 250–340 K at pressures from saturation up to 30 MPa. The measurements, performed in a transient hot-wire instrument employing two anodized tantalum wires as the heat source, have an estimated uncertainty of ±0.5%. A recently developed semiempirical scheme is employed to correlate successfully the thermal conductivity and the viscosity of these refrigerants, as a function of their density.     

R32和R32/R1234yf混合工质黏度实验测量及模型

本文针对含HFOs类混合制冷剂黏度开展实验和模型研究。采用振动弦法黏度计对R32纯质和R32/R1234yf混合制冷剂黏度进行了实验测量,测量的温度范围分别为263~350 K、263~360 K,压力最高均为30 MPa,实验系统黏度测量的不确定度为2%。本文共获得了177组实验数据,利用得到的实验数据,基于硬球模型分别拟合了R32纯质和R32/R1234yf混合制冷剂黏度方程。R32纯质黏度实验数据与方程的平均绝对偏差为0.28%,最大绝对偏差为0.92%;R32/R1234yf混合工质黏度实验数据与方程的平均绝对偏差为0.69%,最大绝对偏差为2.09%。由此可见,实验数据和黏度模型吻合较好,为R32和R32/R1234yf混合制冷剂的应用研究提供了重要参考依据。     

Liquid Thermal Conductivity of Ternary Mixtures of Difluoromethane (R32), Pentafluoroethane (R125), and 1,1,1,2-Tetrafluoroethane (R134a)1

The thermal conductivities of ternary refrigerant mixtures of difluoromethane (R32), pentafluoroethane (R125), and 1,1,1,2-tetrafluoroethane (R134a) in the liquid phase have been measured by the transient hot-wire method with one bare platinum wire. The experiments were performed in the temperature range of 233 to 323 K and in the pressure range of 2 to 20 MPa at various compositions. The measured data are correlated as a function of temperature, pressure, and composition. From the correlation, we can calculate the thermal conductivity of pure refrigerants and their binary or ternary refrigerant mixtures. The uncertainty of the measurements is estimated to be ±2%.     

Measurements of the viscosity of refrigerants in the vapor phase

Measurements of the viscosity of refrigerants R124, R125, R134a, and R152a in the vapor phase are presented. The measurements, performed in a new vibrating-wire instrument, cover a temperature range from 273 to 333 K from about atmospheric pressure up to below the saturation pressure. The uncertainty of the reported values is estimated to be better than ±1%. Comparison with measurements of other investigators reveals a lack of reliable data in the vapor region for these compounds. Paper presented at the Fourth Asian Thermophysical Properties Conference., September 5–8, 1995, Tokyo, Japan.     

Liquid Thermal Conductivity of Binary Mixtures of Pentafluoroethane (R125) and 1,1,1,2-Tetrafluoroethane (R134a)

Thermal conductivities of zeotropic mixtures of R125 (CF₃CHF₂) and R134a (CF₃CH₂F) in the liquid phase are reported. Thermal conductivities have been measured by a transient hot-wire method with one bare platinum wire. Measurements have been carried out in the temperature range of 233 to 323 K and in the pressure range of 2 to 20 MPa. The dependence of thermal conductivity on temperature, pressure, and composition of the binary mixture is presented. Measured thermal conductivity data are correlated as a function of temperature, pressure, and overall composition of the mixture. The uncertainty of our measurements was estimated to be better than 2%.