Helium pool boiling critical heat flux under various magnetically controlled gravity levels

Abstract

The characterization of Critical Heat Flux (CHF) under magnetic compensation of gravity in liquid helium (LHe) is particularly important for the design of the future very high magnetic field superconducting magnets. Through a series of experimental sessions, the critical heat flux in LHe pool boiling has been determined under various gravity conditions ranging from 0.03g to 2.2g using magnetic forces. It is the largest range of gravity variation, from reduced to hyper-gravity, ever studied in a single facility so far. The study was conducted in a very high magnetic field up to 30 T. The magnetic compensation of gravity does not allow for perfect resulting gravity homogeneity. Nevertheless, for the first time, the magnetic field configuration is considered in the experimental results analysis. The relative resulting gravity inclination with respect to the heat exchange surface is also taken into account. The experimental results are compared with the well-known CHF correlation in LHe pool-boiling and show a very good behavior agreement. For our experimental gravity level, the CHF is ranging from 3000 W/m2 to 12000 W/m2.