Gas Capture in a Cavity with Porous Walls

A configuration like an upside-down bell made of porous material is considered which is initially dry but then subjected to a rising pool of liquid. As liquid touches the rim of the bell, capillary transport is initiated. Starting with a vertical wicking phase, the imbibing liquid will eventually reach the ceiling of the bell and switch over to horizonal wicking. At the end of the horizontal wicking, the cavity inside the porous bell is enclosed by liquid and the gas inside it is captured. We present a model to describe the capillary transport in the bell for both Cartesian and cylindrical geometry. As far as possible, we derive analytical solutions to the normalized differential equations that describe the problem. Beyond analytical solutions, we use Runge–Kutta shooting method to obtain numerical results. We calculate the normalized closure time to capture the gas, the amount of captured gas, and reflect on the pressure development in the gas chamber.