Thermal conductivity of a silica gel + calcium chloride system: The effect of adsorbed water

The effective thermal conductivity of a KSK porous silica gel + calcium chloride composite is measured at T=293 K using the hot-wire method, and the effect of the quantity w of sorbed water on it is studied. It is shown that the w-dependence of the thermal conductivity λ is determined by the degree of filling of the matrix pores with a salt + water system and by the phase transitions in this system. The value of λ increases with a filling increase, this occurring most sharply when a continuous phase of the aqueous solution of salt is formed inside the sorbent layer. The results obtained are adequately described by the Luikov-Bjurström model.