Experimental Technology For Studying Heat Transfer Characteristics Of Porous Media Channels With Strong Internal Heat Source

Water-cooled pebble-bed reactor is a new conceptional reactor which owns the excellences of the spherical fuel and the water-cooled reactor. It is very safe and economical. On the background of water-cooled pebble-bed reactor, an experimental loop with strong heat generating porous media channel was designed, and technology for the experiment was also developed, and power distribute and heat transfer characteristics has been researched by experiment.The loop uses water as flowing media, and the test section is packed with oxidized stainless steel spheres. The non-contact electromagnetic induction heating method was used in the loop, it provides a strong and continuous control heat source. It is the real loop for studying the heat transfer characteristics of porous media channels with strong heat source.As the induced current skin effect, the temperature inside the porous media field distribution is very uneven, in order to predict the uneven nature, a porous medium model was built in this paper, and finite element analysis was used in the electric-magnetic-thermal coupling fields to prdict temperature field distribution in the porous media under the condtion of insulation among the spheres. From the simulation results, we can know the themal conditions inside the porous medium, many reasonable methods were proposed in this paper to solve the problem by adjusting the radius of porous medium and the current penetration depth as well as the magnetic field strength, material properties and structural design. The improved test section design is much more than simply transplanting industrial application of electromagnetic induction heating method into the experimental loop.Because of the experimental requirements, various parameters of major equipment operating conditions in accordance with the standard of JB/T81-94, have to be calculated. We also designed the condensor, the water-water heat exchanger, the heater, the steam separator and other equipments, which are necessary for the experimental loop. In the end, we completed the overall design and installation.of the experimental system.In view of visualization requirements of forced convection heat transfer in porous media channel with strong heat source, a test section for visualized experiment and its seal methodwere designed, which facilitated the following experiments for the flow pattern and bubble behavior observation and so on.By experimental research,local power wascalculated by using zoning laws. The relationship of heat transfer coefficient and the Reynolds number was correlated under the power of 30 kW and 15 kW.The experimental results show that the power has no effect on the heat transfer coefficient at atmospheric pressure. The average heat transfer coefficient rapiddly increases with the increase of Reynolds number, the entrance effect affected the heat transfer coefficient greatly. Heat transfer in porous media was also performed by using the software of Fluent. The error of the heat transfer coefficient is less than 8%.