Pressure Dependence Of Thermal Conductivity Research Articles

Method for Measuring Pressure Dependence of Thermal Conductivity of Gases

A simple and sensitive method has been devised for measuring the pressure dependence of the thermal conductivity of gases. The method uses the high thermoelectric power of a semiconductor for the accurate measurement of a temperature difference. Data at 25°C for argon, nitrogen, and helium to 3000 atm and carbon dioxide to 1300 atm are given. The results are compared with those of other investigators and agreement is generally better than 10%, using a two point calibration, and better than 3% using a multipoint calibration.

Pressure Dependence of Thermal Conductivity in Amorphous Materials

Pressure Dependence of Thermal Conductivity in Amorphous Materials

Errata: ``Contributions of Bound, Metastable, and Free Molecules to the Second Virial Coefficient and Some Properties of Double Molecules'' and ``Initial Pressure Dependence of Thermal Conductivity and Viscosity''

Errata: ``Contributions of Bound, Metastable, and Free Molecules to the Second Virial Coefficient and Some Properties of Double Molecules'' and ``Initial Pressure Dependence of Thermal Conductivity and Viscosity''

Initial Pressure Dependence of Thermal Conductivity and Viscosity

The initial pressure dependence of thermal conductivity and viscosity of gases is considered to arise from molecular association and collisional transfer. Since only the initial pressure dependence is investigated, clusters larger than dimers can be neglected. The effect of dimer formation can be calculated from a knowledge of the equilibrium constant for the reaction 2A⇌A2. The effect of collisional transfer is obtained by a semiempirical modification of Enskog's theory. In the case of thermal conductivity, it is found that at low temperatures molecular association is more important than collisional transfer, while at high temperatures collisional transfer predominates. For viscosity, the initial pressure dependence is due primarily to collisional transfer. Detailed equations for the initial pressure dependence of both thermal conductivity and viscosity are given in terms of dimensionless groupings which include the intermolecular potential parameters. Tables of these dimensionless groupings as functions of a reduced temperature are given for molecules obeying the Lennard-Jones (6–12) potential. Comparisons between theory and experiment are included. It is found that the numerical results are sensitive to the choice of force constants for the interaction of a monomer with a dimer.