Numerical simulation of divided-bar thermal conductivity measurements

Summary

A three-dimensional numerical model of the divided-bar thermal conductivity measuring device that can include both solid and fluid sample portions 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 material on the thermal conductivity calculated from the bar temperature measurements. The results show that the positions of the temperature sensors and thus the nature of the vertical column between the temperature measuring points is of prime importance, and that the sizes of the solid and fluid portions of the sample affect the sample conductivity estimates. The divided bar measures the thermal conductivity parallel to the axis of the bar. Thermal conductivity variations in the radial direction have little effect on the calculated conductivity. Whether or not the sides of the bar are insulated strongly affects the calculated conductivity.