Flow instability study of a natural circulation loop with supercritical fluids
Supercritical flow instability in a natural circulation loop with a single horizontal heated channel was experimentally and numerically studied. The experiment was conducted at pressures from 7.6 to 8.6 MPa and inlet temperatures from 10 to 22 C with supercritical CO2. A total of 13 flow instability cases were obtained. Parametric effects such as system pressure, inlet temperature, and heated channel outlet local loss were concluded from steady-state flow-power curve. The effect of different loop configurations, as well as the valve on the connecting line on flow instability, was also investigated. The CATHENA code was used to model the current experimental loop with supercritical water. Flow instabilities were numerically studied with an open loop and a loop connected with accumulator (reservoir) models. Factors that may affect the predictions of steady state results with CATHENA code were discussed and the effect of accumulator as well as the valve on the connecting line was also tested.