Daniel G. Friend

Thermodynamic Properties of Air and Mixtures of Nitrogen, Argon, and Oxygen From 60 to 2000 K at Pressures to 2000 MPa

A thermodynamic property formulation for standard dry air based upon available experimental p–ρ–T, heat capacity, speed of sound, and vapor–liquid equilibrium data is presented. This formulation is valid for liquid, vapor, and supercritical air at temperatures from the solidification point on the bubble-point curve (59.75 K) to 2000 K at pressures up to 2000 MPa. In the absence of reliable experimental data for air above 873 K and 70 MPa, air properties were predicted from nitrogen data in this region. These values were included in the determination of the formulation to extend the range of validity. Experimental shock tube measurements on air give an indication of the extrapolation behavior of the equation of state up to temperatures and pressures of 5000 K and 28 GPa. The available measurements of thermodynamic properties of air are summarized and analyzed. Separate ancillary equations for the calculation of dew and bubble-point pressures and densities of air are presented. In the range from the solidif...

Thermophysical Properties of Ethane

New correlations for the thermophysical properties of fluid ethane are presented. The correlations are based on a critical evaluation of the available experimental data and have been developed to represent these data over a broad range of the state variables. Estimates for the accuracy of the equations and comparisons with measured properties are given. The reasons for this new study of ethane include significant new and accurate data and improvements in the correlating functions which allow increased accuracy of the correlations—especially in the extended critical region. Short tables of the thermophysical properties of ethane are included. This study complements an earlier study of methane and uses the same correlating equations and format. For the thermodynamic properties, a classical equation for the molar Helmholtz energy, which contains terms multiplied by the exponential of the quadratic and quartic powers of the system density, is used. The resulting equation of state is accurate from about 90 K t...

A Helmholtz Free Energy Formulation of the Thermodynamic Properties of the Mixture (Water + Ammonia)

A thermodynamic model incorporating a fundamental equation of state for the Helmholtz free energy of the mixture {water+ammonia} is presented which covers the thermodynamic space between the solid–liquid–vapor boundary and the critical locus. It is also valid in the vapor and liquid phases for pressures up to 40 MPa. It represents vapor–liquid equilibrium properties with an uncertainty of ±0.01 in liquid and vapor mole fractions. Typical uncertainties in the single-phase regions are ±0.3% for the density and ±200 J mol−1 for enthalpies. Details of the data selection and the optimization process are given. The behavior of the fundamental equation of state is discussed in all parts of the thermodynamic space.

New International Formulation for the Viscosity of H2O

The International Association for the Properties of Water and Steam (IAPWS) encouraged an extensive research effort to update the IAPS Formulation 1985 for the Viscosity of Ordinary Water Substance, leading to the adoption of a Release on the IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance. This manuscript describes the development and evaluation of the 2008 formulation, which provides a correlating equation for the viscosity of water for fluid states up to 1173K and 1000MPa with uncertainties from less than 1% to 7% depending on the state point.

Thermophysical Properties of Methane

New correlations for the thermophysical properties of fluid methane are presented. The correlations are based on a critical evaluation of the available experimental data and have been developed to represent these data over a broad range of the state variables. Estimates for the accuracy of the equations and comparisons with measured properties are given. The reasons for this new study of methane include significant new and more accurate data, and improvements in the correlation functions which allow increased accuracy of the correlations especially in the extended critical region. For the thermodynamic properties, a classical equation for the molar Helmholtz energy, which contains terms multiplied by the exponential of the quadratic and quartic powers of the system density, is used. The resulting equation of state is accurate from about 91 to 600 K for pressures <100 MPa and was developed by considering PVT, second virial coefficient, heat capacity, and sound speed data. Tables of coefficients and equatio...

Transport properties of a moderately dense gas

The initial density dependences of both viscosity and thermal conductivity are calculated according to a microscopically based theory which includes effects due to collisional transfer (from only free two-body phase space), three-monomer collisions, and monomer—dimer collisions. A Lennard-Jones potential is used to model the interactions. Comparison of the calculated results with experiment (in reduced form) shows very good agreement for both viscosity and thermal conductivity over a wide temperature range.

Cubic crossover equation of state for mixtures

Abstract In a preceding publication [S.B. Kiselev, Fluid Phase Equilibria 147 (1998) 7], a general procedure was proposed for transforming any classical equation of state (EOS) for pure fluids into a crossover EOS which incorporates the scaling laws asymptotically close to the critical point and is transformed into the original classical EOS far from the critical point. In the present paper, we extend this procedure and develop a cubic crossover equation of state for mixtures. A comparison is made with experimental data for pure methane, ethane, CO2, and for the methane+ethane and CO2+ethane mixtures in the one- and two-phase regions. The cubic crossover equation of state yields a satisfactory representation of the thermodynamic properties and the vapor–liquid equilibria of pure fluids and fluid mixtures in a large range of temperatures and densities, including the dilute gas limit, liquid densities, and the critical region.

New International Formulation for the Thermal Conductivity of H2O

The International Association for the Properties of Water and Steam (IAPWS) encouraged an extensive research effort to update the IAPS Formulation 1985 for the Thermal Conductivity of Ordinary Water Substance, leading to the adoption of a Release on the IAPWS Formulation 2011 for the Thermal Conductivity of Ordinary Water Substance. This paper describes the development and evaluation of the 2011 formulation, which provides a correlating equation for the thermal conductivity of water for fluid states from the melting temperature up to 1173 K and 1000 MPa with uncertainties from less than 1% to 6%, depending on the state point.

Survey and Assessment of Available Measurements on Thermodynamic Properties of the Mixture {Water+Ammonia}

Mixtures of water and ammonia play an important role in absorption refrigeration cycles and have received attention as working fluids in modern power generation cycles. For design and simulations during the development of any application, the thermodynamic properties have to be known accurately. Measurements of available thermodynamic data are compiled and summarized. The data sets are compared, using a Helmholtz free energy formulation. Recommendations are given for which data sets are suited to serve as a basis for an equation of state formulation of the thermodynamic properties of {water+ammonia}. Gaps in the database are shown to give experimenters orientation for future research.

Prediction of the thermal conductivity of refrigerants and refrigerant mixtures

Abstract We use an extended corresponding states model to predict the thermal conductivity of pure halocarbon refrigerants and refrigerant mixtures. The model uses R134a (1,1,1,2-tetrafluoroethane) as the reference fluid, and we present a correlation, including critical enhancement, for the thermal conductivity of R134a. We give sample results comparing the model predictions with experimental data for pure halocarbon refrigerants and refrigerant mixtures; typically, the uncertainty of the predictions is 5–10 percent.