Investigation of the Water Draining Process Pushed by Gas for U-Type and Z-Type Manifolds

In the experimental advanced superconducting tokamak (EAST), the cooling channels of plasma-facing components (PFCs) are familiarly connected in parallel through manifolds. According to the drainage performance of the PFCs, the amount of water trapped in the cooling channels is directly correlated with the type of manifolds. To date, manifold types have been well studied with respect to single-phase and mixed multiphase flow characteristics. However, there are few studies on the drainage performance relevant to the type of manifolds. The friction effect and inertia effect in the manifold intake and exhaust are studied through theoretical analysis. In addition, the draining liquid effect in the branches is dependent on the pressure difference and the resistance coefficient. Furthermore, U-type and Z-type manifolds are studied with FLUENT to discuss their drainage capability in this study. The distribution of the water volume fraction, pressure, and flow ratio is obtained to verify that the Z type is more effective than the U type when applied in the drainage process. This is also supported by comparing the experimental value of the two in drainage discharge. This study will provide a theoretical basis for future upgrades of EAST drainage systems.