General solution for the time lag of a single-tank receiver in the Knudsen flow regime and its implications for the receiver's configuration

Constant volume systems are commonly used for the determination of the diffusion, permeability and solubility coefficients of gases in porous and nonporous media. In this paper we present important considerations for the design of an outflow receiver of a constant volume system to minimize the possible resistance to gas transport downstream from the tested medium. The receiver considered in this paper consists of main tube, a tank, and a tube connecting the main tube with the tank. The resistance of the receiver is quantified using the concepts of the asymptotic solution and the time lag by assuming that gas accumulation in the receiver occurs in the Knudsen flow regime. The effects of the volume of the tank, the position at which the tank is connected to the main tube, the length of the connecting tube, as well as, the position of the pressure sensor in the receiver are discussed.