H. Hendl et al., A NEW EVALUATION OF (P, RHO, T) MEASUREMENTS ON STEAM WITH CORRECTIONS FOR THE EFFECTS OF PHYSICAL AND CHEMICAL ADSORPTION, Journal of Chemical Thermodynamics, 29(7), 1997, pp. 765-784
The precision of (p, rho, T) measurements on fluids suffers from the e
ffects of impurities, of physical and chemical adsorption and desorpti
on at the walls of the measuring vessel, and of the chemical reaction
of the substances at higher temperatures. A study of the low-density v
olumetric behaviour of steam in a large temperature range performed by
our group some years ago showed these difficulties in the evaluation
of the experiments, too. New measurements on n-alkane vapours and thei
r analysis with respect to a physically reasonable behaviour of isothe
rmal data prompted new evaluation of the older measurements on steam.
Influences of physical adsorption and of chemisorption are particularl
y taken into account in order to extract reliable values of the second
virial coefficient B in the temperature range 381 K to 524 K. A consi
stency test including recommended values of the density and pressure f
or the saturated vapour proves the high quality of these data for the
second virial coefficient, which are more positive than B values from
the literature derived from experimental (p, rho, T) data in the same
temperature range. (C) 1997 Academic Press Limited.