Three-medium treatment of heat transfer in porous media and its application in CICC

Abstract

In this article, we derive the multi-temperature macroscopic model suitable for the porous CICC structure by using the volume average method. A CICC porous structure usually consists of three phases: one moving fluid phase (typically liquid helium) and two solid phases (typically copper and superconducting alloy). With the assumption of the equal average temperatures of the two solid phases, we obtain a two-temperature macroscopic model. The relevant closure problems are derived and solved numerically for a JT-60SA CICC structure and a ITER-TFPS CICC structure to obtain the macroscopic parameters. The calculated internal heat transfer coefficients are consistent with the experiment results, indicating the accuracy of the proposed two-temperature model. From the proposed two-temperature model, the temperature difference between the fluid and solid phases can be evaluated under a given heat source, which helps to determine whether the one-temperature model can be applied, or the two-temperature model needs to be applied. Typically, the one-temperature model may be suitable for CICC under nominal operation conditions, and the multi-temperature model is necessary during quenching process.