Analysis on coupled heat transfer with boiling phase transition of helical coiled tube steam generator for liquid metal fast reactor

Le résumé fourni par la source

Lead-bismuth fast reactors, as a fourth-generation reactor type, have significantly improved operational parameters and efficiency, presenting broad application prospects. Facing the service environment of high temperature differences, variable heat flux, and strong phase transitions, the stability and efficiency of heat transfer in the internal helical coil steam generator are crucial. To this end, considering the entire three-dimensional structure including the lead-bismuth fluid region, the water-steam fluid region, and the solid metal region of the tube wall. Numerical models of coupled heat transfer for simplified structures of helical coil steam generators with single tube and double tubes in lead-bismuth fast reactors were constructed. The models incorporate variable property calculation correlations for lead-bismuth and water-steam to account. The VOF multiphase flow method was used to calculate and track the changes in the phase interface of gas-liquid two-phase flow, and the Lee model was employed to consider the mass and energy transfer between the two phases during the evaporation of the water-steam. Based on the present model, the temperature field, velocity field, and gas-liquid phase distribution characteristics of the primary side lead-bismuth and the secondary side water-steam were calculated and analyzed. Heat flux distribution along the steam generator is extremely uneven, with the maximum heat flux reaching 1439.97 kW·m-2 and the minimum only 267.62 kW·m-2. For the parallel double helical coil tube structure, the heat transfer was stronger in the tube with a smaller helical diameter. The average wall heat flux difference between helical tubes with helical diameters of 200 mm and 600 mm was about 1.1 times.

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