Numerical analysis of gas separator with thermal transpiration in micro channels II

Abstract

A membrane gas separator which operates with only a small temperature difference across a membrane is designed, and its capability is numerically proved. The separator system consists of three Knudsen pumps – a motionless pump that utilizes the thermal transpiration of the rarefied gas. Each pump is composed of a porous membrane and one channel along each of the two surfaces of the membrane. Two of the pumps induce a variation of mole fraction using a combination of the thermal transpiration and pressure driven flow through the membrane, and the other one provides the former two pumps with a required pressure difference. This paper reports the first numerical calculations that demonstrate a neon-argon binary gas mixture can be separated into pure neon gas and argon gas with the proposed design. The temperature difference is no more than 90 K, and the total length of the membrane is ∼ 15 cm at standard ambient temperature and pressure. The production rate of the separator is proportional to the width of the membrane. For example, when the width is 10 cm, the flow rates of the product gases are 0.8 sccm for argon and 1.9 sccm for neon.