VACUUM SORPTION PUMPING STUDIES WITH PURE GASES ON MOLECULAR SIEVES.

Low-pressure, low-temperature adsorption of N//2 and CO//2 was studied in beds of 4A molecular sieves. System parameters were estimated by a comparison of experimental results and a molecular-flow theoretical model. The general objective of the work was to develop a mathematical model to describe quantitatively the mass transfer in a deep-bed cryosorption pump. A set of equations describing these processes was derived from theory, and a numerical solution of the set was developed. Major assumptions in the theoretical model were: isothermal conditions, parabolic concentration profile within the sorbent particles, equilibrium adsorption isotherms represented in a Langmuir form, and concentration-independent solid diffusion controlled by either the intracrystalline or the macropore structure.