Boiling heat transfer of liquid helium induced by thermal disturbance in superconductors

Abstract

This paper investigates the fluid-solid coupling boiling heat transfer between superconductor and liquid helium using the Multiple-Relaxation-Time (MRT) pseudo potential lattice Boltzmann model. The reliability of the numerical model is verified by Laplace law and thermodynamic consistency of helium medium. This work focuses on pool boiling, with an emphasis on the influence of surface wettability and thermal disturbance in the superconductor. The numerical results reveal the boiling curves of liquid helium with different surface wettability and the four phases of boiling. Additionally, the flow field of liquid helium boiling, including the nucleation, growth, and detachment of a single helium bubble, is simulated and analyzed in detail. And we also study the temperature changes of superconductor under different thermal disturbances and current densities. It can be found that nuclear boiling caused by smaller thermal perturbations has a high cooling efficiency, whereas larger thermal perturbations cause film boiling with a much lower cooling efficiency. Meanwhile, the hydrophobic surface reduces the critical heat flux for liquid helium boiling, which causes liquid helium to initiate film boiling at a lower superheat, severely inhibiting the cooling capacity of liquid helium.