Thermal Conductivity Of Binary Mixtures Research Articles

Thermal conductivity of binary mixtures of sulphur dioxide and inert gases

Thermal conductivity of SO 2-Ar and SO 2-Kr mixtures have been measured for various compositions over the temperature range 39–200·6°C by using the hot-wire method. The observed values are found to vary nonlinearly with composition at all temperatures. An attempt has been made to explain the observed data in the light of Hirschfelder-theory based on local chemical equilibrium assumptions.

Methods of calculating thermal conductivity of binary mixtures involving polyatomic gases

The experimental binary thermal conductivity data of nineteen different gas pairs have been discussed and the competence of the rigorous, approximate and empirical procedures to represent them is investigated and discussed. In addition a new semi-theoretical method is suggested and tested. The suggested semi-theoretical procedure works very satisfactorily and is of good accuracy. It also compares favourably with the other methods. We also suggest a procedure for estimating thermal conductivity values at high temperature. This is an interesting and useful suggestion in view of the great practical need and their meagre availability.

Thermal conductivity of binary mixtures of carbon dioxide, nitrogen, and ethane at high pressures: Comparison with correlation and theory

AbstractA secondary thermal conductivity cell of the horizontal, concentric cylinder type was developed. The thermal conductivity of the pure gases nitrogen and ethane and approximately 20, 40, 60, and 80% binary mixtures of carbon dioxide, nitrogen, and ethane were determined at 75°C. to 3,000 atm. Several predictive techniques were investigated and recommendations are made.

A comparison of experimental and theoretical values of the thermal conductivity of binary mixtures of nitrogen and hydrogen

Recent experimental measurements of the thermal conductivity of mixtures of nitrogen and hydrogen are compared with values calculated from Hirschfelder’s theory of the transport of heat in mixtures of polyatomic gases. The discrepancies between theory and observation, though small, appear to be greater than the experimental error; the observed thermal conductivities almost always exceed the theoretical values. Similar small discrepancies have been reported in some other experimental work. It is shown that for mixtures of nitrogen and hydrogen the discrepancies are unlikely to be due to a failure to assign correct values to the parameters appearing in the theroretical equations. Attention is therefore drawn to the validity of the assumptions underlying the theory. Hirschfelder’s theory distinguishes translational and internal contributions to the conductivity of the mixture. It rests on the assumption, originally due to Eucken, that the translational contributions to the thermal conductivity of the individual constituents may be calculated as if the gases were monatomic, i.e. by setting K trans. = 2·5 nc v trans. .It is suggested that this is an overestimate of the translational contribution and that complete accuracy is therefore not to be expected from calculations based on Hirschfelder’s theory. A recent theoretical study by Mason & Monchick is in accord with this suggestion.

Viscosity and Thermal Conductivity of Binary Gas Mixtures: Krypton-Argon, Krypton-Neon, and Krypton-Helium

The coefficients of viscosity and thermal conductivity of binary mixtures of krypton with argon, neon and helium have been determined over the full range of composition of each mixture at a pressure of 70 cm of mercury and at a temperature in the range 18.0 to 18.3°C. The experimental values are compared with theoretical values based on the Lennard-Jones (6-12) potential of interaction between molecules. Agreement between the experimental and calculated values is generally satisfactory, but there are discrepancies between some of the measurements given here and those of other workers.

351. Thermal conductivity of binary mixtures of diatomic and monatomic gases: B.N. Srivastava and A.K. Barua, J. Chem. Phys., 32, 427–435, Feb. 1960

351. Thermal conductivity of binary mixtures of diatomic and monatomic gases: B.N. Srivastava and A.K. Barua, J. Chem. Phys., 32, 427–435, Feb. 1960

Viscosity and Thermal Conductivity of Binary Gas Mixtures: Xenon-Krypton, Xenon-Argon, Xenon-Neon and Xenon-Helium

The coefficients of viscosity and thermal conductivity of binary mixtures of xenon with krypton, argon, neon and helium have been determined experimentally over the full range of composition of each mixture at a pressure of 70 cm of mercury and at a temperature in the range 18.0 to 18.3°C. Values of the dimensionless quantity f = λ/ηcv have been obtained for each mixture. The experimental values are compared with theoretical values based on the Lennard-Jones (6-12) potential of interaction between molecules, using force constants derived from viscosity data. Agreement between the experimental and theoretical results is not complete. It is suggested that the discrepancies may be due principally to deficiencies in the empirical rule recommended in the literature for determining the force constant, 12/k, for interactions between unlike molecules.

Thermal Conductivity of Binary Mixtures of Diatomic and Monatomic Gases

Thermal conductivity of the binary mixtures of O2–He, O2–Ne, O2–Kr, and O2–Xe have been measured at 30°C and 45°C for various compositions by using the thick-wire-variant of the hot-wire method. For pure O2 the experimental value of the thermal conductivity is lower than that given by the recent theory of Hirschfelder based on the assumption of local chemical equilibrium, and consequently the values calculated from Hirschfelder's formula for the mixture conductivities are also expected to be higher than the experimental values which is actually found to be so for the mixtures investigated here. The agreement becomes excellent when the experimental values of the conductivity of pure O2 are used to calculate the mixture conductivities. The formula for the mixture conductivities has been tested in detail and was found to give satisfactorily the composition dependence. The simpler formula for the thermal conductivity of gas mixtures given by Mason and Saxena has also been tested.

Approximate Formulas for the Viscosity and Thermal Conductivity of Gas Mixtures

Approximate expressions for the viscosity and thermal conductivity of gas mixtures have been derived from the rigorous kinetic theory formulas. Three levels of approximation are distinguished, with the third approximation rigorous for binary mixtures. The first approximation for mixture viscosity is found to be very nearly equivalent to empirical expressions known heretofore. The first and second approximations for mixture conductivity have been compared with rigorous calculations for binary mixtures of nonpolar gas pairs; the first approximation has an average error of 2.6% while the second approximation reduces this error to 0.5%. The second approximation accounts for the thermal conductivity of binary mixtures of polar and nonpolar gases. (It is assumed that the interchange of translational energy is abnormal for the polar-polar interaction.)

Thermal Conductivities of Organic Vapor Mixtures

The thermal conductivities of binary mixtures of organic vapors have been investigated in the temperature range 60—125°C. When nonpolar vapors of similar viscosity and molecular weight are used, the variation of conductivity with composition of the mixture is roughly linear. Mixtures of nonpolar and strongly polar vapors, on the other hand, exhibit pronounced maxima in the conductivity vs composition curves. The difference in behavior is due to the strong interaction between polar molecules on collision.