Yun Jin Kim

EXPERIMENTAL STUDY ON THE DOUBLE-EVAPORAT OR THERMOSIPHON FOR COOLING HTS (HIGH TEMPERATURE SUPERCONDUCTOR) SYSTEM

Cryogenic thermosiphons are highly efficient heat transfer elements between a cryocooler and the thermal load that is to be cooled. This paper presents an idea of thermosiphon that peculiarly utilizes two evaporators to overcome spatial restriction. A so-called double-evaporator thermosiphon was designed, fabricated and tested using nitrogen under sub-atmospheric pressure condition. This thermosiphon is specifically aimed for cooling HTS bulk system. In this paper, the invisible interior condition of the double-evaporator themosiphon is described in detail during the cool-down process according to the internal thermal states. Although the double-evaporator thermosiphon worked successfully under sub-atmospheric pressure condition, there was a little temperature difference between two evaporators at steady-state operation. The cause of this problem is considered as the orientation effect of boiling heat transfer coefficient. An additional experiment was also conducted to examine the orientation effect of boiling heat transfer coefficient of nitrogen under sub-atmospheric pressure condition.