B. Le Neindre

Experimental determination of the thermal conductivity of molten pure salts and salt mixtures

The thermal conductivity of some molten salts was measured at atmospheric pressure, using the coaxial cylinder method. The pure compounds NaCO3, KNO3, and NaNO2, the equimolar mixture NaNO3-KNO3, and HITEC, which is a three-component mixture, NaNO3-NaNO2-KNO3 (0.07-0.40-0.53 in weight), were investigated. For mixtures, it was found that the experimental thermal conductivity coefficients are in agreement with calculated values using a simple linear mixing law. The thermal diffusivity was calculated and compared with experimental data.

Determination of the thermodynamic properties of water from measurements of the speed of sound in the temperature range 251.15–293.15 K and the pressure range 0.1–350 MPa

The speed of sound in water has been measured in a broad region around the liquid-solid transition, that is, in the temperature range from 251.15 K to 293.15 K and in the pressure range from 0.1 to 350 MPa. An iterative method of calculation was used to determine the thermodynamic properties in the same P-T diagram. Anomalies observed for the isothermal compressibility and the specific heat at constant pressure are discussed in terms of statistical mechanical considerations.

Density of HCFC 142b and of its mixture with HCFC 22

Abstract The density of the binary mixture 40/60 wt% of monochlorodifluoromethane (HCFC 22) and 1-chloro-1,1-difluoroethane (HCFC 142b) in the liquid phase, has been measured between 300 and 370 K and pressures up to 19 MPa, with an oscillating fork densimeter, operating in a relative mode. Toluene and vacuum have been used as calibrating fluids. The accuracy of the data is 0.08 %. An equation for the dependence of density in temperature and pressure for HCFC 142b and for this mixture is also presented.

Thermal conductivity measurement of n-butane over wide temperature and pressure ranges

The thermal conductivity of n-butane has been measured by a coaxial-cylinder method over a pressure range from 0.1 MPa up to 70 MPa and a temperature range from room temperature to 600 K, covering all fluid states. The estimated accuracy of the method is about 2%. Special emphasis has been given to the behavior of the thermal conductivity near the critical point, and the critical enhancement has been studied for 3.6 K<δT<176 K. The effect of inelastic collisions upon transport properties of the dilute gas has been discussed. The results obtained for the reduced critical enhancement as a function of the reduced critical temperature confirm the universality of the critical exponent, for the n-alkanes, whereas the reduced excess thermal conductivity outside the critical region is a function of the reduced density and of the n-alkane.

Simple grid technique to measure refractive index gradients

Abstract A simple optical device is described which provides very precise measurements of refractive gradients in transparent media. In this method the distortion of the shadow of a grid induced by the gradient is measured. The numerical integration of this gradient gives the refractive index profile in the medium. The method is used to study the stratification and the phase separation of a very compressible fluid (near-critical CO 2 ) in the Earths gravitional field.

The thermal conductivity of 1-chloro-1,1-difluoroethane (HCFC-142b)

The thermal conductivity of 1-chloro-1,1-difluoroethane (HCFC-142b) has been measured in the temperature range 290 to 504 K and pressures up to 20 MPa with a concentric-cylinder apparatus operating in a steady-state mode. These temperature and pressure ranges cover all fluid states. The estimated accuracy of the method is about 2%. The density dependence of the thermal conductivity has been studied in the liquid region.

Thermal conductivity of dense noble gases

We report thermal conductivity measurements for noble gases at 25°C and pressures up to 1 GPa or to the solidification point. The experimental results are compared with the thermal conductivity data previously obtained in the Van der Waals Laboratory for the noble gases and the data are analyzed in terms of a temperature-independent excess thermal conductivity.

Thermal conductivity of steam from 250 to 510°C at pressures up to 95 MPa including the critical region

New measurements of the thermal conductivity of steam have been performed in the temperature range 250–510°C and in the pressure range from 1 up to 95 MPa. Most of the measurements were taken at temperatures greater than the critical temperature, where the enhancement of the thermal conductivity is observed. The experimental values are compared to the IAPS formulation for the thermal conductivity of water.

Measurements of the Thermal Conductivity of HFC-125 in the Temperature Range from 300 to 515 K at Pressures up to 53 Mpa

Measurements of the thermal conductivity of HFC-134a made in a coaxial cylinder cell operating in steady state are reported. The measurements of the thermal conductivity of HFC-134a were performed along several quasi-isotherms between 300 and 530 K in the gas phase and the liquid phase. The pressure ranged from 0.1 to 50 MPa. Based on the experimental data, a background equation is provided to calculate the thermal conductivity outside the critical region as a function of temperature and pressure. A careful analysis of the various sources of errors leads to an estimated uncertainty of ±1.5%.

Measurements of the Thermal Conductivity of HFC-32 (Difluoromethane) in the Temperature Range from 300 to 465 K at Pressures up to 50 MPa

New measurements of the thermal conductivity of HFC-32, made in a coaxial cylinder cell operating in steady state, are reported. The measurements were performed along several quasi-isotherms between 300 and 465 K in both the liquid and the vapor phases. The pressure ranged from 0.1 to 50 MPa. Based on the experimental data, a background equation is provided to calculate the thermal conductivity outside the critical region as a function of temperature and density. A careful analysis of the various sources of experimental errors leads to an estimated uncertainty of ±1.5%. Comparisons between calculated and experimental values from the literature are presented.