Experimental study of pressure drop oscillation in a supercritical carbon dioxide natural circulation loop

Pressure drop oscillation (PDO) is a common type of instability in a two-phase system. The PDO may occur in a supercritical fluid system, with limited prior research on the matter. In this study, an experimental study on PDO of supercritical carbon dioxide (S-CO2) in a natural circulation loop has been carried out. The influence of thermal parameters and compressible volume has been investigated. The experimental result shows that PDO occurs in a natural circulation loop of supercritical carbon dioxide. The location and compressibility capacity of the pressurizer greatly impacts the instability characteristics of the natural circulation loop. The large volume pressurizer installed at the outlet of hot section helps to stabilize the system. The amplitude and the period are influenced by the heat flux and the location of the compressible volume. Increasing the heat flux will slightly increase the amplitude and decrease the period. This work helps to clarify the mechanism of PDO of S-CO2 in the natural circulation loop and provides a reference for the safe design and operation of S-CO2 energy conversion systems.