Thermal conductivity of unsaturated packed beds - comparison of experimental results and estimation methods

The heat transfer in unsaturated moist packed beds containing a volatile liquid is reviewed by discussing the main transport mechanisms, measurement techniques, experimental results and prediction methods. Attention is focused on the description of the heat transfer by effective thermal conductivities at low temperature gradients without free or forced convection. Possible sources of error in interpretation of experimental results are discussed. Several estimation methods are tested with experimental results of different authors and fitted values for the model parameters are presented. A comparison of the estimation methods reveals that Okazaki's model is the most reliable. (C) 1997 Elsevier Science S.A.