Conductance of Packed Spheres in Vacuum

An analytical study is presented for the heat transfer through the solid phase of a packed bed of spheres bounded by two infinite plane surfaces of different temperatures. The prediction of the conductance is based on the constriction resistance for spheres in contact. Both exact and approximate equations are derived for solid, hollow, and coated spheres and for several regular packing patterns of different void fractions. Comparisons with the available experimental data indicate that the theory is satisfactory over a wide range of applied load and system parameters.