A new temperature–thermal conductivity relationship for predicting saturated liquid thermal conductivity

Abstract

A new temperature–thermal conductivity relationship similar to the Rackett equation for saturated liquid densities is proposed. The first-order group contribution values proposed earlier for predicting the thermal conductivity at the normal boiling point [S.R.S. Sastri, K.K. Rao, Chem. Eng. 100(8) (1993) 106–107] are revised. Combining these two, the thermal conductivities of organic liquids are predicted over the entire saturated liquid region using the normal boiling point, critical temperature and chemical structure as inputs. Below the normal boiling point, the average absolute deviation and the maximum absolute deviation between the predicted data and the literature data are 5.6% and 28.9%, respectively. These figures compare favourably with those of the Nagvekar method [M. Nagvekar, T.E. Daubert, Ind. Eng. Chem. Res. 26 (1987) 1562–1565], claimed to be the best available one applicable to all types of liquids. The deviations between the predicted and literature values are of the same order as the variations in the experimental data, even at temperatures upto 0.98 T r, where T r is the reduced temperature. The proposed correlation is in agreement with the observation of B.C. Sakiadis and J. Coates [AIChE J. 1 (1955) 275–288] regarding the near constancy of the pseudo critical thermal conductivity for members of the homologous series, but it does not support their other expectations regarding the regularity in the variation in the thermal conductivity and temperature coefficient of thermal conductivity for these liquids. The periodic variation in the temperature coefficient with the number of carbon atoms observed by J.D. Raal and R.L. Rijisdijk [J. Chem. Eng. Data 26 (1981) 351–359] for n-alcohols is also not supported.