Heat Transfer Model for Predicting Thermal Conductivity of Highly Compacted Bentonite.

A mechanistic heat transfer model of highly compacted bentonite is developed to derive equations predicting the thermal conductivity. In the model clearances between molecular layers in the montmorillonite particles and spaces among the particles constructing the bentonite are assumed to be small and large voids of rectangular parallelepipeds, dispersing in the continuous phase. The volumetric fractions of both the small and the large voids vary depending on the porosity of the bentonite. The effects of degree of water saturation on the thermal conductivity of the bentonite is considered by changing the effective thermal conductivity of the voids depending on water contents in the voids. Predicted values of the thermal conductivity agree fairly well with the data measured for Na-bentonite (MX-80 and Kunigel-V1) with bulk densities between 1.4g/cm3 and 1.8g/cm3 corresponding to the porosity 0.33