Prediction of helium vapor quality in steady state Two-phase operation for SST-1 Toroidal field magnets

TL;DR

This paper models and analyzes the vapor quality of helium in the steady-state two-phase flow of SST-1 superconducting magnets, providing insights into thermo-hydraulic behavior during operation.

Contribution

It introduces a method to predict helium vapor quality in SST-1 magnets during steady state, validated against experimental data and existing correlations.

Findings

Vapor quality can be estimated from heat load data.

Experimental results align with established two-phase flow correlations.

Helium flow characteristics are critical for magnet stability.

Abstract

Steady State Superconducting Tokamak (SST-1) at the Institute for Plasma Research (IPR) is an operational device and is the first superconducting Tokamak in India. Superconducting Magnets System (SCMS) in SST-1 comprises of sixteen Toroidal field (TF) magnets and nine Poloidal Field (PF) magnets manufactured using NbTi/Cu based cable-in-conduit-conductor (CICC) concept. SST-1, superconducting TF magnets are operated in a Cryo-stable manner being cooled with two-phase (TP) flow helium. The typical operating pressure of the TP helium is 1.6 bar (a) at corresponding saturation temperature. The SCMS has a typical cool-down time of about 14 days from 300 K down to 4.5 K using Helium plant of equivalent cooling capacity of 1350 W at 4.5 K. Using the onset of experimental data from the HRL, we estimated the vapor quality for the input heat load on to the TF magnets system. In this paper, we report the characteristics of two-phase flow for given thermo-hydraulic conditions during long steady state operation of the SST-1 TF magnets. Finally, the experimentally obtained results have been compared with the well-known correlations of two-phase flow.