Reference Correlation of the Thermal Conductivity of Toluene from the Triple Point to 1000 K and up to 1000 MPa

This paper contains new, representative equations for the thermal conductivity of toluene. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. Although there are a sufficiently large number of data at normal temperatures, data at very low and very high temperatures as well as near the critical region are scarce. In the case of the dilute-gas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. Moreover, in the critical region, the experimentally observed enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter. The correlations are applicable for the temperature range from the triple point to 1000 K and pressures up to 1000 MPa. The overall uncertainty (considered to be estimates of a combined expanded uncertainty with a coverage factor of two) of the proposed correlation is estimated, for pressures less than 700 MPa and temperatures less than 550 K, to be less than 3% for the liquid, while for the region 550 K <= T <= 700 K the uncertainty is estimated to be 4%. For the region T > 700 K and 500 MPa <= p <= 1000 MPa, the equations can safely be used with an uncertainty of the order of 10%. Finally, the uncertainty along the saturation line is estimated to be 2% with a coverage factor of two. (C) 2012 by the U.S. Secretary of Commerce on behalf of the United States. All rights reserved. [http://dx.doi.org/10.1063/1.3700155]