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

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 conductivit y 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 u sing the normal boiling point, critical temperature and chemical structure as inputs. Below the normal boiling point, the average absolute deviation a nd the maximum absolute deviation between the predicted data and the litera ture data are 5.6% and 28.9%, respectively. These figures compare favourabl y with those of the Nagvekar method FI. Nagvekar, T.E. Daubert, Ind. Eng. C hem. Res. 26 (1987) 1562-1565], claimed to be the best available one applic able to all types of liquids. The deviations between the predicted and lite rature values are of the same order as the variations in the experimental d ata, even at temperatures upto 0.98 T-r, where T-r is the reduced temperatu re. The proposed correlation is in agreement with the observation of B.C. S akiadis and J. Coates [AIChE J. 1 (1955) 275-288] regarding the near consta ncy of the pseudo critical thermal conductivity for members of the homologo us series, but it does not support their other expectations regarding the r egularity in the variation in the thermal conductivity and temperature coef ficient of thermal conductivity for these liquids. The periodic variation i n 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-al cohols is also not supported. (C) 1999 Elsevier Science S.A. All rights res erved.