Experimental and numerical of passive cooling natural circulation loops

The study focuses on the use of passive safety features in the design of next-generation reactors and understanding key thermal-hydraulic phenomena influencing their performance. The experiment uses a circular glass tube with an orange shape, a heater, and a heat exchanger. The system’s behavior under varying power inputs (500 W, 1000 W, and 1500 W) is observed, with temperature and flow data recorded at multiple points. The experimental test rig consists of a heating section, a cooler, two gate-type valves, and (1/2)-inch class pipes and fittings. The device is filled with water and emptied, and cold water is prepared in an insulated tank at a constant temperature of 20 °C. A pump is operated to pass cold water over the device, and temperature readings are taken by type K thermocouples before entering the heater and after exiting the heater, and by a data logger number 2 in the middle of the system. The numerical section analyzes natural circulation flows related to passive safety loops in water nuclear reactors, involving inherent unsteadiness, laminar-to-turbulent transition, and thermal stratification phenomena. The study also assesses models that solve the Reynolds-Averaged Navier-Stokes equations using ANSYS Fluent in a forced convection 2-D channel flow case. Experimental research interests in various energy systems encourage further experiments on the natural circulation and stability characteristics of horizontal heater and horizontal cooler rectangular loops. The system reaches thermal equilibrium after 2000 seconds, with oscillation patterns at 1000 W and 1500 W. Heat transfer processes control its behavior, with the Reynolds number determining flow patterns. Excellent thermal performance, stability at 287 K, and varying components emphasize uniform cooling