A SUMMARY REPORT OF THE CRYOSORPTION PUMPING OF HYDROGEN BY CARBON DIOXIDE FROST
Abstract
The sorption of hydrogen by cryodeposited frosts of CO2, SO2, and CH3C1 at temperatures between 12 and 22 degrees K has been investigated both analytically and experimentally. Equilibrium sorption isotherms and the dynamic pumping characteristics of the sorbent, sorbate combination were systematically measured for chamber pressures between ten to the minus seven and ten to the minus four torr. Frost cryosorbents which were formed in a manner to make them more amorphous exhibited greater equilibrium sorption capacities for hydrogen. Carbon dioxide sorbents were formed which were able to sorb one hydrogen molecule for every two predeposited CO2 molecules. It was found that equilibrium sorption isotherms of frost cryosorbents could be predicted by the semi- empirical Dubinin-Radushkevich Equation. A general model of the sorption dynamics was formulated and approximate closed-form solutions were obtained: in the limit of rather compact frost whose sorption behavior would be limited by the ability of the molecules to penetrate and diffuse into the frost, and in the limit of very porous frosts in which the adsorption rate on the frost surface governs the pumping. Theoretical calculations for these limiting cases agreed with the observed pumping characteristics of the more compact and more porous frosts.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1970
- Accession Number
- AD0707844
Entities
People
- K. E. Tempelmeyer
Organizations
- Arnold Engineering Development Complex