The residual heat exchanger in nuclear power plant is the key component of secondary side passive residual heat removal system, where the performance of removing decay heat by condensation and pool boiling to the secondary water storage tanks in the residual heat exchanger is crucial to the safety of the nuclear power plant. In the present paper, an experimental facility is built to evaluate the heat removal capability of the residual heat exchanger in both steady state natural circulation and forced circulation at different pressures. The high pressure steam is forced to flow and enter into heat exchanger with a slight inclined tube, which is installed in a large water pool. Experiments are carried out to study the characteristics of the steam condensation in the residual heat exchanger at different parameters. A calculation code for modeling this process and predicting the outlet temperature is also developed.
The results show that the temperature difference between inlet and outlet increases with the increase of the inlet steam pressure due to the variation of latent heat. Meanwhile, the outlet temperature also increases with increasing flow rate. The calculation results accord with the experimental data at low mass flow rate. It is also found that the two calculation models proposed by J.R. Thome predict the flow pattern well, and the Shah’s equation is more suitable to estimate the heat transfer characteristic.