ИСТИНА

The method of separating mixtures of gases with different molecular masses during outflow into vacuum through supersonic micronozzles was introduced back in the middle of last century [1]. However, proper numerical simulation of this effect was impossible due to lack of computing power and thus simplified approaches were used [2]. In recent years, studies of separation of binary mixture outflowing into vacuum through micronozzles [3], microchannels/microslits [4] and microorifices [5] regained significant interest. In present study we performed numerical simulations of aeroseparation of a Helium-Argon mixture in a converging-diverging micronozzle, aiming to determine geometrical and operational parameters for most efficient separation. It was shown that fine tuning of micronozzle geometry can indeed enhance separation efficiency. However, the simplest microslit was demonstrated to provide comparable performance and may be preferable to micronozzles due to its configurational simplicity. Beyond that, placement of product gas extraction area (Fig. 1) was shown to be very important for separation process and its proper choice may be the key factor for effective separation (Fig. 2). It was also obtained that purity of product gas does not depend on inlet Knudsen number in range Kn ≥ 0.01, while production rate is inversely proportional to Kn. This mean that high rarefaction inside micronozzle is not necessary for effective separation.