Experimental Investigation of Multilayer Insulation With Room Temperature Outside and Liquid Helium Temperature Inside

Abstract

Experiments on multilayer insulation were conducted with the conditions of room temperature outside and liquid helium temperature (4.2K) inside. By varying the total number of radiation shields, heat trans fer rate and transverse layer-by-layer temperature distribution were measured. Experimental data with liquid nitrogen (77K) were also ob tained and the difference in heat transfer rate between from room tempera ture to liquid helium temperature and from room temperature to liquid nitrogen temperature was demonstrated. Prior to the experiment, preliminary consideration was made as to the determination of each radiation shield temperature in multi-shield system. A single parameter A, which represents the conductive to radiative heat transfer ratio, was introduced, and it is shown that in the case of constant emissivity, the temperature distribution may be computed with the simple method introduced in this investigation. From the temperature distribution thus obtained, it is possible to calculate the total heat transfer rate and the radiative to total heat transfer ratio at each radiation shield with various boundary temperature conditions and the number of radiation shields.