Heat transfer enhancement of upward flowing supercritical water by Y-shaped through rib

The overall safety of a Supercritical Water-cooled Reactor (SCWR) highly lies in the heat transfer performance of cooling system. This paper investigates the upward flow and heat transfer of supercritical water in a 2 × 2 rod bundle channel with a new Y-shaped longitudinal ribs through numerical simulation. When the Y-type longitudinal ribs are presented, the cooling channel is divided into several sub-channels, preventing fluid from flowing to the center of the channel due to pressure differences, making the fuel rod outer wall temperature more uniform and alleviating the heat transfer deterioration. At the same time, the introduction of Y-shaped ribs increases the mass flow rate of fluid in the cooling channel by 30% to 65%, and due to the existence of heat conduction effect, the temperature of Y-shaped ribs reaches 70% - 85% of the fuel rod wall temperature, which increases the heat transfer area. The increase in mass flow rate and heat transfer area improves the heat transfer efficiency between the coolant and the fuel rods. The Y-shaped ribs can increase the heat transfer coefficient by 10% - 56%, and the pressure loss is only increased by 10% - 40%, which is better than traditional positioning lattice frames.