EVAPORATION CHARACTERISTICS AND EFFICIENT WORKING AREA OF MULTI-STAGE HIGH PRESSURE AND TEMPERATURE REDUCING VALVE

A well understanding on the evaporation characteristics and efficient working area of multi-stage high pressure and temperature reducing valve (MSHPTRV) is important for improving the performance and safety of MSHPTRV. The water spraying and evaporation model are integrated into the flow model of MSHPTRV. Compared with the experimental data, the model can show the thermal process well. The flow characteristics and interaction between steam and droplets are presented. On this basis, the increase rate of entropy, S-dis, is adopted to analyze the thermodynamic loss and innovatively determine the efficient working area of MSHPTRV. The results show that the pressure reducing effect of the second orifice plate is prominent, which accounts for 41.6% of the total pressure drop. The "steam-water layer" is formed at the boundary of steam and water. At the inlet of second orifice plate, the maximum S-dis is 0.782, and the downstream of second orifice plate is the efficient working area of MSHPTRV. The length of evaporation section increases with the droplets diameter significantly.