Transport property measurements on the IUPAC sample of 1,1,1,2-tetrafluoroethane (R134a)

This paper reports the results of an international project coordinated by t he Subcommittee on Transport Properties of Commission 1.2 of the Internatio nal Union of Pure and Applied Chemistry. The project has been conducted to investigate the large discrepancies between the results reported by various authors fur the transport properties of R134a and culminates the effort wh ich was initially described in 1995. The project has involved the remeasure ment of the transport properties of a single sample of R134a in nine labora tories throughout the world in order to test the hypothesis that at least p art of the discrepancy could be attributed to the purity of the samples. Th is paper provides an intercomparison of the new experimental results obtain ed for the viscosity and thermal conductivity in the vapor, liquid, and sup ercritical gas phases. The viscosity measurements were made with a variety of techniques including the vibrating wire, oscillating disk, capillary flo w, and falling body. Thermal conductivity was measured using transient bare and anodized hut wires, steady-state anodized hut wires, and light scatter ing. Agreement between a variety of experimental techniques using the stand ard round-rubin sample is necessary to demonstrate that some of the discrep ancies in earlier results were due to sample impurities. Identification of disagreement between data using one experimental technique relative to othe r techniques may suggest modifications that would lead to more accurate mea surements on these highly petal refrigerant materials. It is anticipated th at the new data which have been measured on this IUPAC round-robin sample w ill aid in the identification of the rt liable data sets in rhs literature and ultimately allow the refinement of the IUPAC reference-data correlation s for the transport properties of R134a.