Investigation of natural convection in large pools

Natural convection is a basic principle for a lot of industrial processes. As an example for the investigation of natural convection phenomena, the paper describes investigations of a passive heat removal system in advanced designs of nuclear power plants. Modern Boiling Water Reactor concepts includes emergency condensers. In the Research Centre Jülich at the NOKO-test facility experiments were performed, to investigate the heat transfer capability of an emergency condenser under different operation modes. Recently the heating up phenomena on the secondary side of the condenser were investigated in detail. The paper describes simulations performed in the Forschungszentrum Rossendorf using the CFD code CFX-4, developed by AEA-Technology, and comparisons to the experiments. Applying the Boussinesq approximation the simulation of the heating up process is possible, at least qualitatively. Using the laminar approach, temperature oscillations caused by plumes could be simulated. Performing additional calculations, measures to avoid undesired temperature stratification were investigated.