Heat Transfer Through a Multilayer Insulation System as a Function of Pressure in the Cryostat Vacuum Space
When one builds a high quality cryostat, one strives to have a good vacuum (better than 1 mPa) in the space where there is multilayer insulation between the cryogen vessel and the outer vacuum vessel. When designing any cryostat, one should always ask the following question; What happens if the insulting vacuum is not good? This paper presents a technique for analyzing the performance of a cryogenic insulation system when the insulating vacuum is not so good. From the analytical calculations presented in this report, one can improve the insulation system so that acceptable insulation performance can occur even when the pressure in the vacuum space is as high as 100 mPa. Of particular interest is the calculation of insulation performance when the vacuum fails. The difference between an air or nitrogen leak, and a helium leak or a hydrogen leak is illustrated.
KeywordsHeat Transfer Vacuum Space Plate Spacing Multilayer Insulation Combine Heat Transfer
Unable to display preview. Download preview PDF.
- 1.E. M. Sparrow and R. D. Cess, Radiation Heat Transfer, Brooks/Cole Publishing Company, Belmont CA, (1966)Google Scholar
- 2.Frank Kreith, Principles of Heat Transfer. International Textbook Company, Scranton PA, (1961)Google Scholar
- 3.James Jeans, An Introduction to the Kinetic Theory of Gases, Cambridge Press, (1962)Google Scholar
- 4.V. D. Arp and R. D. McCarty, “Thermophysical Properties of Helium-4 from 0.8 K to 1500 K with Pressures to 1000 MPa,” MST Tech Note 1334, November 1989Google Scholar
- 5.V. J. Johnson editor, A Compendium of Properties of Materials at Low Temperature (Phase 1). Part 1 Properties of Gases, Pergamon Press, New York, (1961)Google Scholar
- 6.M. A. Green, “Radiation and Gas Conduction Heat Transport Across a Helium Dewar Multilayer Insulation System,” The Art and Science of Magnet Design, a Festschrift in Honor of Klaus Halbach. Vol. 1, p 191, LBL PUB-754 (February 1995)Google Scholar
- 7.C. Y. Lin and L. Lees, Rarefied Gas Dynamics, p 391, Edited by L. Talbot, Academic Press, New York (1961)Google Scholar
- 8.W. P. Teagan and G. S. Springer, “Heat Transfer and Density Distribution Measurements between Parallel Plates in the Transition Regime,” MIT Fluid Mechanics Laboratory Report 67–5, September 1967Google Scholar