Heat transfer characteristics of one side heated vertical rectangular channel when a copper wire is inserted intermittently with a high porosity

A very high-temperature reactor (VHTR) is one of the next generation nuclear reactor systems. A gas cooling system with natural circulation is considered as a candidate for the pressure vessel cooling system (VCS) of the VHTR. The Japan Atomic Energy Agency is pursuing the design and development of commercial systems such as the 300 MWe gas turbine high-temperature reactor 300 for cogeneration (GTHTR300C). These is a need for a passive method in which the cooling system operates even when all power is lost in the accident of a nuclear power plant. The gas cooling system with natural circulation is considered as a candidate for the VCS of the VHTR. In the VCS of the GTHTR300C, many rectangular flow channels are formed around the reactor pressure vessel. A cooling panel utilizing natural convection of air has been proposed. However, the amount of removed heat is inferior to that of cooling by forced convection. Hence, we propose a method of inserting a porous material into the heating surface to promote heat transfer. In this study, we use an experimental apparatus that simulated the cooling panel of VCS. The experimental apparatus is a U-shaped flow channel, and the heating surface side is a vertical rectangular flow channel. Fine copper wire (diameter: 1.5 mm) was used as a porous material. A porosity of the channel is changing from 0.996 to 0.999. We investigated the amount of removed heat by intermittently inserting metal wires into the one side heated vertical rectangular channel to reduce the pressure drop. (author)