Thermal Energy Transport Parallel to the Laminations in Multilayer Insulation
The use of cryogenic liquid propellants such as hydrogen, fluorine or oxygen in long-term space missions is strongly dependent on the effectiveness of thermal insulation systems and the predictability of their thermal performance. Laminar insulations, which currently exhibit high thermal performance, are typically composed of metallized plastic thermal radiation shields, and some include alternate spacer materials, such as fiberglass paper, that reduce the conductive heat transport between radiation layers. Published data [1,2] show that such insulation systems developed to date exhibit very high resistance to heat flow normal to the laminations; however, it is evident from the nature of the material that it should exhibit high anisotropy, and this could seriously affect the overall insulation thermal performance where structural members and feedlines penetrate the insulation or where the vehicle spatial surface temperature varies greatly. Until recently, in estimating the heat transport along the laminations, the bulk properties of the metallized film have been used. However, data presented recently  for the double-aluminized Mylar-Dexiglas system established that the “size” effect of the aluminized film governed the parallel heat flow and that the overall parallel thermal conductivity can be significantly lower than conductivity based on the bulk-aluminum properties. Furthermore, radiation transfer along the laminations was found to be relatively insignificant for this system.
Unable to display preview. Download preview PDF.
- 1.R. M. Coston and C. A. Zierman, “Cryogenic Thermal Conductivity Measurements of Insulating Materials,” Presented at ASTM Symposium on Thermal Conductivity Measurements of Insulating Materials at Cryogenic Temperature, Philadelphia, Pa. (Feb. 1966).Google Scholar
- 2.I. A. Black and P. E. Glaser in; Advances in Cryogenic Engineering, Vol. 9, Plenum Press, New York (1964), p. 52.Google Scholar
- 3.R. M. Costón and G. C. Vliet, “Thermal Energy Transport Characteristics Along the Laminations of Multilayer insulations,” presented at the 1967 Thermophysics Specialists Conference, New Orleans, La. (Apr, 17, 1967). Google Scholar
- 4.E. M. Sparrow, “Radiant Emission» Absorption and Transmission Characteristics of Cavities and Passages,” Symposium on Thermal Radiation of Solids, San Francisco, Calif. (Mar, 4–6, 1964).Google Scholar