par Waelbroeck, F. 
;Bingen, Roald ;Prigogine, Ilya
Référence Physica, 21, 6-10, page (667-675)
Publication Publié, 1955
;Bingen, Roald ;Prigogine, Ilya Référence Physica, 21, 6-10, page (667-675)
Publication Publié, 1955
Article révisé par les pairs
| Résumé : | In a real gas, and in the presence of a temperature gradient, the relative concentrations of the clusters vary from point to point; this leads to a diffusion of the larger clusters towards the warm regions, and of the smaller clusters and single particles towards the cold parts of the apparatus, where they respectively dissociate or recombine with the absorption or liberation of the heat of association. The increase in the thermal conductivity of the gas resulting from this “circulation” of the heat of formation of the clusters can be evaluated with reasonable accuracy at low pressures, where only monomers and dimers need to be taken into account. This effect is negligible at “high” temperatures (above the Boyle point), where the variation of the thermal conductivity λ with pressure can be represented to a high degree of accuracy by Enskog's hard sphere theory; it increases with decreasing temperature, and becomes approximately equal to the Enskog effect in the neighborhood of the critical temperature; it is evaluated that in the case of Argon, the increase is of the order of 6 % . atm−1 at the boiling point.At higher pressures, the larger clusters, which carry an important heat of formation, can no longer be neglected; as an exact calculation is difficult, some simplified models are briefly discussed. The corresponding excess thermal conductivity, for homopolar molecules, is largely due to clusters with internal cyclic links. |
