Theoretical model for the thermal conductivity of a packed bed of solid spheroids in the presence of a static gas, with no adjustable parameters except at low pressure and temperature

Many analytical models exist for the thermal conductivity of packed pebble beds in a static gas, but all require adjustable parameters to give good fits to experimental data. The present paper differs from earlier ones in including a measurable parameter for the particle roughness. With this, the conductivity for an uncompressed bed can be calculated with no adjustable parameters, provided the conductance of the solid is much greater than that of the gas and gas pressures are above about 4 kPa. Agreement with experimental data is typically within 15% over a wide range of temperature and pressure.