Experimental Study on the Natural Circulation System for Single-Phase Water

The investigation on a natural circulation system for single-phase water is of value for engineering application, which has been researched by various methods. In the present study, a natural circulation experiment for single-phase water in a rectangular loop was conducted, in which water was electrical heated in a tank at the bottom of the loop and cooled by pool boiling outside of the tube bundles at the top of the loop. The system pressure was 2–6 MPa and heating power was 10–30 kW. Results show that natural circulation flow increases with heating power as a straight line for the same pressure, while no obvious influence of pressure on circulation flow for the same heating power can be found. In addition, a contrast experiment was carried out with different system resistance for further study, and it was found that the system resistance could significantly decrease heat exchange efficiency of the natural circulation system, which mainly resulted from distinctly reductive circulation flow. Emphasis was also put on extending the correlation proposed by Vijayan to the present experiment.