CFD analysis on two-phase pipe flow of slush nitrogen

CFD analysis on the fundamental two-phase flow characteristics of slush nitrogen in a corrugated duct is conducted to develop effective cooling performance for superconducting cable. First, the governing equations of two-phase slush nitrogen flow based on the unsteady thermal non-equilibrium two-fluid model are constructed and several flow characteristics are numerically calculated taking into account the effects of the slush volume fraction, the thermodynamic behavior of slush, and the duct shape. Results of this research show that it is possible to reduce the pressure loss by using a two-phase slush flow under the high Reynolds number condition. It is also found that the reduction of the pressure loss is dominated not only by applying the appropriate size and volume fraction of slush particles, but also by the slush pumping effect that acts on the liquid-phase acceleration due to the momentum exchange between slush and liquid-phases. Furthermore, it is numerically predicted that with two-phase slush flow, the friction coefficient has a smaller value in the high Reynolds number region than that with single-phase flow.