Experimental and Analytical Investigation of the Effect of Cryodeposits on the Radiation Properties of Plain and Extended Surfaces
Abstract
In the thermal design of a cryopumped space simulation chamber, the absorptance of the 77 deg K cold wall for solar and room temperature radiation and the absorptance of the 20 deg K cryowall for 77 deg K and reflected solar radiation should be considered. The absorptances of the above surfaces depend on the substrate material, type and thickness of the condensable gas deposited, the geometry of the surface, and the source of incident radiation. Experiments for determining the cryo-deposited film heat transfer parameters and an analytic study of two extended surface configurations are described. The following investigations were made of: (1) hemispherical absorptance of water vapor and carbon dioxide deposits at 77 deg K for 290 deg K radiation as a function of deposit thickness, with plain aluminum and aluminum coated with a black epoxy paint as substrates, (2) normal absorptance of water vapor deposits at 77 deg K for radiation from a Mercury-Xenon source (with and without a filter) as a function of deposit thickness, with aluminum coated with a black epoxy as the substrate, and (3) hemispherical absorptance of nitrogen, dry air, and carbon dioxide deposits at 20 deg K with plain aluminum as the substrate. Analytic determinations of the effective absorptance (or emittance) of V-groove and honeycomb extended surface geometries were also made. The results of the experimental data and of the analytical studies indicate that for a 80 to 100 deg K high absorptance cold wall, the ice and CO2 deposits formed on this cold-wall surface will not appreciably reduce the absorptance of this surface and that the air, N2, and C02 films condensed on a 20 deg K cryopumping surface will not significantly increase the thermal load on this surface.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1963
- Accession Number
- AD0425490
Entities
People
- A. S. Gilcrest
- C. A. Zierman
- J. P. Millard
- R. P. Caren
- W. F. Schmidt
Organizations
- Lockheed Martin