Gas permeability of expanded graphite-metallic salt composite

The expanded graphite-metallic salt composite was manufactured by impregnation of metallic salt solution into porous graphite matrix, followed by vacuum drying. The gas permeability was measured by using Darcy's law in ammonia atmosphere for the graphite-CaCl2. nNH(3) (n = 8, 4, 2), MnCl2. nNH(3) (n = 6, 2) and BaCl2. nNH(3) (n = 8, 0) composites. The gas permeability was in the range of 5.0 x 10(-16)-10(-12) m(2) depending on the reaction pair, bulk density and weight fraction of the graphite powder. Results show that as the value of n increases, the gas permeability diminishes remarkably due to a reduction of the total porosity. The values of gas permeability obtained in this work are useful in the mass transfer analysis and dynamic simulation of thermochemical reactors for chemical heat pumps. (C) 2000 Published by Elsevier Science Ltd.