Free-molecular gas flow through the oscillating membrane

Abstract

the main distinguishing features of the track membranessmall thickness and high uniformity of the pore size.In this paper, the possibility of using a high-frequency oscillating track membranes as diffusion membranes for gas separation was studied. High-frequency forced oscillation of the membrane was considered because of assumption that the membrane conductivity for a given gas can be controlled by varying the frequency and amplitude of oscillation. The problem about free-molecular gas flow through a oscillating in its plane membrane was stated, and the possibility of separation of gases using such a device was investigated. Problem statementThe gas flow through moving membrane was studied. Membrane was simulated by rigid body with straight cylindrical channels. Channels length was L (thickness of membrane), channels radius was R, and channels axis was perpendicular to the membrane surface (see Fig. 1). Membrane was placed between two tanks (1) and (2) with constant pressures P 1 , P 2 and temperatures T 1 , T 2 (T 1 = T 2 = T w , where T w -temperature of membrane material).Main assumptions:1. Gas flow inside channel is free-molecular. 2. Velocity distribution for molecules entering from tanks is equilibrium corresponding to tank temperature. 3. All membrane channels are equal-cylinders with length L and radius R. 4. Membrane moves as absolutely rigid body. Law of membrane motion: x = x 0 , y = y 0 + A sin (ωt + φ), z = z 0 . 5. Channel wall temperature T w is maintained constant. AbstractThe free-molecular gas flow through the membrane oscillating in its own plane was studied. Passing probability and velocity distribution function of gas molecules in the membrane were calculated depending on the dimensionless parameters characterizing the geometry of membrane channels, gas molecule mass, gas temperature, frequency and amplitude of the membrane oscillation. It has shown that the conductivity of the membrane for a given gas can be controlled by changing the parameters of forced oscillations.

Study of gas separation by the means of high-frequency membrane oscillations

“…For detailed description, refer to [4]. Assumption that all membrane channels are equal and membrane moves as absolutely rigid body implies that flow can be studied only in one channel.…”

“…Other important application is the construction of novel separation devices working in microgravity [3]. In authors' previous papers [4,5] a novel effect of gas separation using track membranes oscillating with high frequency was discovered; it was shown that varying the amplitude and frequency of oscillations one can control the conductivity of the membrane for the given gas, and as a result, achieve the effect of gas separation. The purpose of the present work is to determine optimal values of membrane oscillation parameters for the most efficient gas separation.…”

Free-molecular gas flow through the high-frequency oscillating membrane

“…For detailed description, please refer to [7]. Assumption that all membrane channels are equal and membrane moves as absolutely rigid body implies that flow can be studied only in one channel.…”

“…The computation was as follows. The same way as in [7], coordinate and velocity of a new gas molecule at the inlet section of the channel were calculated according to given distributions. Then, the point of collision between gas molecule and channel wall was calculated.…”

“…In authors previous papers [7,8] a novel effect of gas separation using track membranes oscillating with high frequency was discovered; it was shown, that varying the amplitude and frequency of oscillations one can control the conductivity of the membrane for the given gas, and as a result, achieve the effect of gas separation. The purpose of the present work is to determine optimal values of membrane oscillation parameters for the most efficient gas separation.…”