Simulation Of Heat Transfer Performance Of Once-through Steam Generator With Flow Resistance Is Considered

In order to meet the high power density and miniaturization of the nuclear power system,once-through steam generator is widely used in China and small nuclear power systems.The secondary side of the once-through steam generator is experienced with complex vapor flow and heat transfer process,and is accompanied by the aggravation of the evaporative heat transfer.It is of great significance to analyze the heat transfer deterioration by the simulation of steady state and dynamic performance of the once-through steam generator.This paper takes a B&W company's once-through steam generator as the prototype,using the method of distributed parameter,considering the mass,momentum and energy conservation,establish a once-through steam generator one-dimensional homogeneous flow model.For steady state and dynamic simulation,the flow and heat transfer performance changes mainly studied the flow pressure drop and the operational parameters of first and second circuit of once-through steam generator to dry the influence law of heat transfer characteristics,different heat transfer simulation program can calculate the starting position and the interval length.Steady state simulation results: by comparing the results of RELAP5 and thermal hydraulic calculation,the maximum relative error is 1.79%,the error is relatively small,and the reliability of the model and simulation code is verified.The results showed that,with the reduction of load,the overall pressure drop of the secondary side decreased,and the 100% load decreased to 30% load,and the pressure drop was 0.014 MPa from 0.243 MPa.As the load decreases,the nucleate boiling area is shortened,the starting point of evaporation is moved forward,the overheated area becomes longer,and the temperature of the starting point of evaporation is not very high.Top up starting point wall temperature rising amplitude changes from 19.8? to 20.5?,the starting point moves from 6.07 m to 1.27 m.Dynamic simulation results: the dynamic simulation results are compared with the RELAP5 calculation results,the maximum relative error is less than 1%,and the error is relatively small.For the step perturbation analysis of different inlet conditions,the enthalpy value of one side enthalpy has the greatest influence on the whole once-through generator.The enthalpy of one side entrances only decreased by 4%,secondary side pressure drop was 0.179 MPa,top up starting point wall temperature rising rate is 18.8?,compared with the full load condition,the amplitude of wall temperature rises 4.0?;The enthalpy value of one side entrance is decreased by 5%,and the outlet fluid of the dc steam generator can not reach overheating.Secondary side entrance enthalpy decreased,the influence of once-through steam generator is not very big,but 30% lower load cases,can lead to disappear preheating section,may cause water hammer phenomenon,therefore,should try to avoid this situation.To sum up,this article through to the stability of once-through steam generator,dynamic heat exchange performance simulation,can quickly and easily analysis the working characteristic of once-through steam generator,to help the operation of the once-through steam generator has a certain reference.