NUMERICAL-SIMULATION OF DIVIDED-BAR THERMAL-CONDUCTIVITY MEASUREMENTS

A three-dimensional numerical model of the divided-bar thermal conduct ivity measuring device that can include both solid and fluid sample po rtions has been developed. The model has been employed to investigate the effects of porosity in divided-bar measurements and the effects of the distribution of solid sample and contained fluids in porous mater ial on the thermal conductivity calculated from the bar temperature me asurements. The results show that the positions of the temperature sen sors and thus the nature of the vertical column between the temperatur e measuring points is of prime importance, and that the sizes of the s olid and fluid portions of the sample affect the sample conductivity e stimates. The divided bar measures the thermal conductivity parallel t o the axis of the bar. Thermal conductivity variations in the radial d irection have little effect on the calculated conductivity. Whether or not the sides of the bar are insulated strongly affects the calculate d conductivity.