Studies of cool-down and mass flow of a vertical liquid nitrogen transfer line

摘要

Cool-down time and mass flow rate behaviour are the most important characteristics of cryogenic transfer lines. The present work relates to the studies of a vertical liquid nitrogen (LN{sub}2) transfer line. A demountable transfer line has been used for this purpose and a dedicated collection system for upward flow measurements has been implemented. Different configurations of the transfer line such as jacketed transfer line with different insulations such as vacuum and vacuum created by gas condensation of carbon dioxide (CO{sub}2) and Freon-22 (R-22) as well as line insulated with multilayer insulations have been studied for upward and downward flows. Generally, the vertical upward flow provides higher liquid mass flow rate compared to downward flow, under the same experimental conditions.