Simulation Analysis of Condensation Heat Transfer Inside C-type Tubes Based on RELAP5/MOD3.2

The RELAP5/MOD3.2 code was validated experimentally for simulating the condensation heat transfer characteristics inside C-type tubes of the passive residual heat removal heat exchanger. In order to eliminate the effects of the boiling model out of tubes when simulating condensation, the C-type tube condensation simulation, in which the wall temperature was given, was performed using RELAP5/MOD3.2 code. Comparing the simulation results with the experimental data, it is found that the maximum relative deviation between the experimental and calculated condensation heat transfer coefficients exceeds 80% in the range of experimental date, and the change tendency of the average condensation heat transfer coefficient is obviously different with the increase in the outlet condensate Reynolds. RELAP5/MOD3.2 code uses Chato model to calculate the condensation of the horizontal part and uses the Nusselt model to calculate the condensation of the vertical part when simulating the C-type condensation experiment in the range of experimental parameters. The results show that the standard code in RELAP5/MOD3.2 cannot give completely reliable predictions when simulating the condensation heat transfer characteristics inside the C-type tubes.