Experimental and analytical study of the effects of noncondensable gas in a tube bundle condenser.

摘要

Passive Containment Cooling System (PCCS) of the Economic Simplified Boiling Water Reactor (ESBWR) is a passive condenser system that allows the transfer of reactor heat via steam condensation to the outer water pool. The PCCS condenser must be able to remove sufficient energy from the reactor containment to prevent containment from exceeding its design pressure following a design basis accident. The presence of noncondensable gas in the vapor can greatly reduce the performance of condensers. Hence a detailed knowledge of the heat removal performance of the PCCS in the presence of noncondensable gas is crucial for the safety and design optimization of the ESBWR.;Condensation experiments were performed for a vertical 4 tubes bundle submerged in a water pool. The present experimental data provides a new database for complete condensation mode, through flow mode, and transient operation of the passive condenser with a tube bundle. The experimental data was also compared with the existing experimental data with vertical sing tube facilities of different tube diameters.;The RELAP5 code modeling of wall condensation was performed. Experimental conditions were simulated with RELAP5. Code simulation showed quite different results compared with data. So, the improvement in RELAP5 condensation model is needed.;From the comparison of tube bundle experimental data with the modeling data by single tube boundary layer model, we found that the tube bundle has a higher secondary HTC. It's due to the tube bundle effect on condensation heat removal. The turbulent mixing on the secondary side decreases the Delta T between pool water and condenser tube outer wall, and causes an increase in secondary HTC. This increase in secondary HTC thus results in higher condensate mass flow rates. Thus the improvements on the boundary layer model and heat and mass analogy model by considering tube bundle effects were conducted and have a good agreement with the existing tube bundle data.