Study On Thermal-hydraulic Characteristics Of Secondary Side In Steam Generator Simplified Into A Low-temperature And Low-pressure Test Device

Steam generator(SG)is one of the four components of nuclear station's main circuit.It functions as heat exchange equipment transforming the main circuit's heat to the secondary circuit where produces saturated steam to supply the dynamic equipment.At the same time,SG is the parclose between main and secondary circuit,preventing the leakage of radio activity.Therefore,studying the flow characteristics and transfer mechanism inside the steam generator is very important for the efficiency and safety of nuclear station.Based on structure characteristics and operation mode of SG,to deal with flow and heat transfer problems in the secondary side,firstly this paper does similar modeling analysis of real SG and put forward a modeling scheme with ratio analysis method combining system decomposition,classification method and the dimensional analysis method.Guaranteeing similarity,the original complex SG is simplified into a single row and small size structure making researches such as measurement more feasible.This also provides a simplified thinking way for complex engineering research.Secondly,according to the modeling scheme,the paper complete structure design of SG test body,corresponding experiment circuit system,auxiliary experimental device and measurement,data acquisition system.In the design of U-shaped pipe,electric heating rod with segmented heat flux density is first used,which can better simulate real U tubes.This design has a certain significance in similar situations.Based on the test bench,analyse the temperature field in the secondary side under different water ratio especially in the horizonal direction and analyse the experimental error caused by the measurement system.Finally,using CFX 14.5,numerical simulation had been done to anlysis the void fraction under different water suply.The result is compared with even water supply,primary bubbles' location is lower and much more nonuniform on horizontal direction in uneven water supply.It means uneven water supply is more effective in bubble production and heat transference than the even one.Studying flow field distribution in SG can further understand the flow characteristics inside SG and provide theories improving structure design and safety of SG.Studying the relationship between velocity field and temperature field could be preparations for further understanding of heat transfer mechanism and enhancing thermal efficiency of SG.