Experimental Investigations on the Steady State and Stability Behaviour of Supercritical Pressure Natural Circulation

Abstract

Natural circulation experiments were carried out in a uniform diameter rectangular loop using supercritical CO₂ and H₂O. Steady state data were generated with supercritical CO₂ with four different orientations of the source and sink. Instability was observed only for the orientation with both the source and sink horizontal over a narrow window of power around the pseudocritical point with low cooling water flow rate. Hence experiments with water were carried out only for this orientation which also showed instability at low coolant flow rates. The steady state flow rates obtained were compared with a generalized flow correlation developed which showed good agreement with present data as well as those reported in literature. The general characteristics of the observed instability are also described in the paper.