Boiling heat transfer to a liquid nitrogen pool from Ag sheathed BiPb2223 tapes carryingover-current

Abstract

Measurements were carried out on boiling heat transfer to a liquid nitrogen pooldue to self-heating of Ag sheathed BiPb2223 tapes with increasing over-currentsup to 300 A, focusing on its difference from increasing heat flux in conventionalheated surfaces. Large spontaneous oscillations of the surface temperature wereobserved and attributed to the interplay between the activation/deactivation ofnucleate boiling and the highly nonlinear heat generation of the superconductor as afunction of temperature. Two distinct steady states of 8 and 3 K superheating werealso found for samples carrying 300 A, depending on the current cycle history.