Study of Noncondensable Effect on Passive Condenser

摘要

In the nuclear reactor industry, condensation heat transfer is very important. The presence of the noncondensable gases in vapors can greatly reduce the condensation process. Noncondensable gas unable to pass into the condensate film accumulates at the liquid vapor-interface leading to a decrease in vapor partial pressure and thus the interface temperature at which condensation occurs. In the advanced light water reactors such as the Westinghouse Electric (WE) designed Advanced Passive 600 MWe (AP600), and General Electric (GE) Simplified Boiling Water Reactor (SBWR) [2], and recently introduced WE AP1000 [3] and GE's 4000MWt simplified boiling water reactor referred as ESBWR [4], there is a greater emphasis on replacing the active systems with passive systems in order to improve the reliability of operation and safety. In the SBWR and ESBWR, the PCCS is a passive heat exchanger that allows the transfer of heat via steam condensation to the 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 efficient performance of the PCCS condenser is thus vital to the safety of the reactor. The rate of heat transfer in the PCCS condenser is strongly coupled to the hydrodynamic characteristics of the PCCS. Three different operational modes are possible in the Passive Containment Cooling System (PCCS) of the Simplified Boiling Water Reactor (SBWR) depending on the non-condensable gas concentration and the pressure difference between the drywell and suppression pool chamber. These are bypass mode (forced flow), complete condensation mode (all incoming vapor is condensed in the tube with no flow through the exit of the tube), and cyclic condensation and venting mode (periodic venting of non-condensable gas that accumulate in the condenser tube). Existing models and experimental data are limited to the bypass mode (forced flow) condensation. An experimental study was performed to investigate the steam condensation heat transfer in the presence of non-condensable gas in a condenser tube, which is scaled from PCCS system."