New functional forms have been developed for multiparameter equations of state for non- and weakly polar fluids and for polar fluids. The resulting functional forms, which were established with an optimization algorithm which considers data sets for different fluids simultaneously, are suitable as a basis for equations of state for a broad variety of fluids. The functional forms were designed to fulfil typical demands of advanced technical application with regard to the achieved accuracy. They are numerically very stable and their substance-specific coefficients can easily be fitted to restricted data sets. In this way, a fast extension of the group of fluids for which accurate empirical equations of state are available is now possible. This article deals with the results found for the polar fluids CFC-11 (trichlorofluoromethane), CFC-12 (dichlorodifluoromethane), HCFC-22 (chlorodifluoromethane), HFC-32 (difluoromethane), CFC-113 (1,1,2-trichlorotrifluoroethane), HCFC-123 (2,2-dichloro-1,1,1-trifluoroethane), HFC-125 (pentafluoroethane), HFC-134a (1,1,1,2-tetrafluoroethane), HFC-143a (1,1,1-trifluoroethane), HFC-152a (1,1-difluoroethane), carbon dioxide, and ammonia. The substance-specific parameters of the new equations of state are given as well as statistical and graphical comparisons with experimental data. General features of the new class of equations of state such as their extrapolation behavior or their numerical stability and results for non- and weakly polar fluids have been discussed in preceding articles.

Equations of state for technical applications. III. Results for polar fluids

Measurements leading to the calculation of the ideal-gas thermodynamic properties for ethylbenzene (Chemical Abstracts registry number [100-41-4]) are reported Experimental methods included adiabatic heat-capacity calorimetry (5 K to 420 K), comparative ebulliometry (306 K to 450 K), and differential-scanning calorimetry (DSC) The critical temperature was measured by DSC Saturation heat capacities for the liquid phase between 420 K and 550 K and the critical pressure were derived with the vapor-pressure and DSC results Results were combined with an enthalpy of combustion reported in the literature to derive standard molar entropies, enthalpies, and Gibbs free energies of formation at temperatures between 250 K and 550 K The standard state is defined as the ideal gas at the pressure p = p° = 101325 kPa Results are compared with literature values for all properties Problems associated with independent statistical calculation of ideal-gas properties for ethylbenzene are discussed

Thermodynamic equilibria in xylene isomerization. 2. The thermodynamic properties of m-xylene

Development of a fundamental equation of state for the liquid region of a pure fluid from speed of sound measurements. Application to water

Bioinspired Untethered Soft Robot with Pumpless Phase Change Soft Actuators by Bidirectional Thermoelectrics

This Review presents the state of knowledge of the thermophysical properties of water in all its phases and the reference formulations that provide standardized, recommended values of these properties for science and industry. The main focus is the standard formulations adopted by the International Association for the Properties of Water and Steam (IAPWS), but some properties are covered for which IAPWS has not yet adopted recommendations. It is emphasized that, despite many advances over the last 100 years, there is room for further improvement, and current weaknesses and opportunities for advancing knowledge are discussed. Particular attention is given to the formulation for thermodynamic properties of fluid water known as IAPWS-95, which is planned to be replaced in the coming years. Additional topics include properties of heavy water and seawater and the growing ability of molecular modeling to provide properties at conditions where experimental measurements are difficult or inaccurate.

B.E Gammon

Papers

A thermoelectric flow enthalpy-increment calorimeter