Volume 41, Issue 2, June 2012

This paper contains new, representative equations for the thermal conductivity of toluene. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. Although there are a sufficiently large number of data at normal temperatures, data at very low and very high temperatures as well as near the critical region are scarce. In the case of the dilutegas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. Moreover, in the critical region, the experimentally observed enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter. The correlations are applicable for the temperature range from the triple point to 1000 K and pressures up to 1000 MPa. The overall uncertainty (considered to be estimates of a combined expanded uncertainty with a coverage factor of two) of the proposed correlation is estimated, for pressures less than 700 MPa and temperatures less than 550 K, to be less than 3% for the liquid, while for the region 550 K ≤ T ≤ 700 K the uncertainty is estimated to be 4%. For the region T > 700 K and 500 MPa ≤ p ≤ 1000 MPa, the equations can safely be used with an uncertainty of the order of 10%. Finally, the uncertainty along the saturation line is estimated to be 2% with a coverage factor of two.
 REGULAR ARTICLES


Reference Correlation of the Thermal Conductivity of Toluene from the Triple Point to 1000 K and up to 1000 MPa
View Description Hide DescriptionThis paper contains new, representative equations for the thermal conductivity of toluene. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. Although there are a sufficiently large number of data at normal temperatures, data at very low and very high temperatures as well as near the critical region are scarce. In the case of the dilutegas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. Moreover, in the critical region, the experimentally observed enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter. The correlations are applicable for the temperature range from the triple point to 1000 K and pressures up to 1000 MPa. The overall uncertainty (considered to be estimates of a combined expanded uncertainty with a coverage factor of two) of the proposed correlation is estimated, for pressures less than 700 MPa and temperatures less than 550 K, to be less than 3% for the liquid, while for the region 550 K ≤ T ≤ 700 K the uncertainty is estimated to be 4%. For the region T > 700 K and 500 MPa ≤ p ≤ 1000 MPa, the equations can safely be used with an uncertainty of the order of 10%. Finally, the uncertainty along the saturation line is estimated to be 2% with a coverage factor of two.

Correlation for the Viscosity of Sulfur Hexafluoride (SF_{6}) from the Triple Point to 1000 K and Pressures to 50 MPa
View Description Hide DescriptionA wideranging correlation for the viscositysurface of sulfur hexafluoride (SF_{6}) has been developed that incorporates generalized friction theory (GFT). The approach requires, as the core thermodynamic model, a referencequality equation of state(EoS). Here the EoS of Guder and Wagner has been selected for that purpose. All available experimental data, to the extent of our knowledge, were considered in the development of the model. The correlation performs best in the lowpressure (less than 0.33 MPa) region from 300 K to 700 K where the estimated uncertainty (considered to be combined expanded uncertainty with a coverage factor of two) is 0.3%. In the region from 300 K to 425 K for pressures less than 20 MPa, the estimated uncertainty is less than 1%. Where there were data available for validation at temperatures from 230 K to 575 K for pressures up to 50 MPa, the estimated uncertainty is 2%. The correlation extrapolates in a physically reasonable manner and may be used at pressures to 100 MPa and temperatures from the triple point to 1000 K.

Thermodynamic Properties of oXylene, mXylene, pXylene, and Ethylbenzene
View Description Hide DescriptionEquations of state for the xylene isomers (oxylene, mxylene, and pxylene) and ethylbenzene have been developed with the use of the Helmholtz energy as the fundamental property with independent variables of density and temperature. The general uncertainties of the equations of state are 0.5% in vapor pressure above the normal boiling point, and increase as the temperature decreases due to a lack of experimental data. The uncertainties in density range from 0.1% in the liquid region to 1.0% elsewhere (the critical and vaporphase regions). The uncertainties in properties related to energy (such as heat capacity and sound speed) are estimated to be 1.0%. In the critical region, the uncertainties are higher for all properties. The behavior of the equations of state is reasonable within the region of validity and at higher and lower temperatures and pressures. Detailed analyses between the equations and experimental data are reported.

Reference Correlation of the Thermal Conductivity of Sulfur Hexafluoride from the Triple Point to 1000 K and up to 150 MPa
View Description Hide DescriptionThis paper contains new, representative reference equations for the thermal conductivity of SF_{6}. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. Although there are a sufficiently large number of data at intermediate temperatures, data at very low or very high temperatures as well as near the critical region are scarce. In the case of the dilutegas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. Moreover, in the critical region, the experimentally observed enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter. The correlations are applicable for the temperature range from the triple point to 1000 K and pressures up to 150 MPa. The overall uncertainty (considered to be estimates of a combined expanded uncertainty with a coverage factor of two) of the proposed correlation is estimated, for pressures less than 150 MPa and temperatures less than 1000 K, to be less than 4%.

IUPACNIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 2. Ca
View Description Hide DescriptionThe alkaline earth carbonates are an important class of minerals. This article is part of a volume in the IUPACNIST Solubility Data Series that compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1 outlined the procedure adopted in this volume, and presented the beryllium and magnesium carbonates. Part 2, the current paper, compiles and critically evaluates the solubility data of calciumcarbonate. The chemical forms included are the anhydrous CaCO_{3} types calcite, aragonite, and vaterite, the monohydrate monohydrocalcite (CaCO_{3}· H_{2}O), the hexahydrate ikaite (CaCO_{3}·6H_{2}O), and an amorphous form. The data were analyzed with two model variants, and thermodynamic data of each form consistent with each of the models and with the CODATA key values for thermodynamics are presented.
