THE INITIAL DENSITY DEPENDENCE OF TRANSPORT-PROPERTIES - NOBLE-GASES

The usual procedure that the transport properties at atmospheric pressure are identified with values in the limit of zero density cannot be accepted for all reduced temperatures T*. It is shown in the framework of the Rainwater-Friend theory for noble gases, as a good example, that for T* < 1 the effect of the initial density dependence has different signs for viscosity and thermal conductivity and amounts to a few percent, when data at atmospheric pressure are compared with zero-density values. An improved representation of the monomer-dimer contribution to the second transport virial coefficients of the Rainwater-Friend theory is presented in the paper. This is based, among others, on the author's own experimental data of the initial density dependence of viscosity of polytomic gases.