Numerical study of a consequence of a vacuum insulation degradation in a cryogenic system. Issue 1 (March 2020)

• Record Type: Journal Article
• Authors: Kopczynski, A.; Baran, B.; Malecha, Z.
• Is Part Of: IOP conference series. Volume 755:Issue 1(2020)
• Publication Date: 2020-03
• Subjects: Materials science -- Periodicals; 620.1105
• DOI: 10.1088/1757-899X/755/1/012115
• Languages: English
• ISSNs: 1757-8981

Abstract

Abstract: Vacuum is the primary method for a thermal insulation of cold elements in cryogenic systems, tanks and other cryogenic equipment. A dangerous situation arise in the case of vacuum envelope failure when a 300 K air enters the vacuum and the cold elements of cryogenics equipment are exposed to a potentially intense heat fluxes and air velocity. Depending on a mass flow of the air (equivalent to size of an insulation rapture), a different rate of the temperature and pressure growth in the vacuum chamber can promote various mechanisms of the heat transfer to the cold elements. Additionally, it can be limited by the air deposition, condensation and cryosorption. In the present work a simplified numerical model of a typical cryogenics system is developed and different scenarios of vacuum degradation are considered. The current studies aim to identify the development of the different thermal conditions in the cryogenics system in the function of the mass flow of the ventilating air. The present work presents numerical studies of vacuum degradation for various sizes of a rapture hole. Additionally, the work proposes a simplified zero-dimensional model, which includes a deposition of air and its influence on pressure buildup and heat transfer.