Study of Supercritical Carbon Dioxide Natural Circulation by the Use of CFD Codes

In this paper, experiments on natural circulation of CO 2 , previously performed at the Bhabha Atomic Research Centre (BARC), are addressed by the use of the FLUENT and the STAR-CCM+ CFD codes. The experiments were carried out in an experimental facility installed at the Reactor Engineering Division of BARC in Mumbai, consisting in a uniform diameter (13.88 mm ID & 21.34 mm OD) rectangular loop (SCNCL) with different orientations of heater and cooler, which can operate with either supercritical water and supercritical carbon dioxide. The tests with carbon dioxide were performed at different power levels, at the supercritical pressures of 8.6 and 9.1 MPa. The steady-state characteristics of the loop were obtained for the horizontal heater and the horizontal cooler configuration (HHHC) and for the horizontal heater and vertical cooler one (HHVC). Unstable behaviour was observed only for the HHHC configuration. The FLUENT and the STAR-CCM+ codes were adopted for reproducing the observed behaviour of the experimental loop in the HHHC configuration. Steady-state as well as transient analyses were performed to be compared with the observed behaviour of the loop