Multiphase Flow Dynamics 4

Transcription

1 Multiphase Flow Dynamics 4 Nuclear Thermal Hydraulics von Nikolay I Kolev 1. Auflage Multiphase Flow Dynamics 4 Kolev schnell und portofrei erhältlich bei beck-shop.de DIE FACHBUCHHANDLUNG Thematische Gliederung: Kontinuumsmechanik, Strömungslehre Springer 2009 Verlag C.H. Beck im Internet: ISBN

2 Table of contents 1. Heat release in the reactor core Thermal power and thermal power density Thermal power density and fuel material Thermal power density and moderator temperature Spatial distribution of the thermal power density Equalizing of the spatial distribution of the thermal power density Nomenclature References Temperature inside the fuel elements Steady state temperature field Transient temperature field Influence of the cladding oxidation, hydrogen diffusion and of the corrosion product deposition Cladding oxidation Hydrogen diffusion Deposition Nomenclature References The simple steady boiling flow in a pipe Mass conservation Mixture momentum equation Energy conservation The idea of mechanical and thermodynamic equilibrium Relaxing the assumption of mechanical equilibrium Relaxing the assumption of thermodynamic equilibrium The relaxation method The boundary layer treatment The boundary layer treatment with considered variable effective bubble size Saturated flow boiling heat transfer Combining the asymptotic method with boundary layer treatment allowed for variable effective bubble size... 60

3 XXVI Table of contents 3.12 Separated momentum equations and bubble dynamics Nomenclature References Appendix 3.1: The Sani s (1960) data for flow boiling in pipe The simple steady three-fluid boiling flow in a pipe Flow regime transition slug to churn turbulent flow Instantaneous liquid redistribution in film and droplets Relaxing the assumption for instantaneous liquid redistribution in film and droplets, entrainment and deposition Drift flux correlations Separated momentum equation Dynamic evolution of the mean droplet size Droplet size stability limit Droplet production rate due to fragmentation Duration of the fragmentation Collision and coalescence Heat transfer Mass transfer Comparison with experiments Nomenclature References Core thermal hydraulic Reactor pressure vessels Steady state flow in heated rod bundles The NUPEC experiment The SIEMENS void data for the ATRIUM 10 fuel bundle The FRIGG experiment The THTF experiments: high pressure and low mass flow Pressure drop for boiling flow in bundles Transient boiling The NUPEC transients in a channel simulating one sub-channel of a PWR fuel assembly The NUPEC transients in PWR 5 5 fuel assembly Steady state critical heat flux Initial 0D-guess D-CHF analysis Uncertainties Outlook towards the large scale turbulence modeling in bundles Outlook towards the fine resolution analysis Core analysis Nomenclature References Appendix 5.1: Some relevant constitutive relationship addressed in this analysis

4 Table of contents XXVII 6. Flow boiling and condensation stability analysis State of the art AREVA boiling stability data for the ATRIUM 10B fuel bundle Flow condensation stability References Critical multiphase flow Definition of the criticality condition Grid structure Iteration strategy Single phase flow in pipe No friction energy dissipation, constant cross section General case, perfect gas Simple two phase cases for pipes and nozzles Subcooled critical mass flow rate in short pipes, orifices and nozzles Frozen homogeneous non-developed flow Non-homogeneous developed flow without mass exchange Equilibrium homogeneous flow Equilibrium non-homogeneous flow Inhomogeneous developing flow in short pipes and nuzzles with infinitely fast heat exchange and with limited interfacial mass transfer Recent state of the knowledge for describing critical flow Bubbles origination Bubble fragmentation Bubble coalescences Droplets origination Examples for application of the theory of the critical flow Blow down from initially closed pipe Blow down from initially closed vessel Nomenclature References Steam generators Introduction Some popular designs of steam generators U-tube type Once through type Other design types Frequent problems Analytical tools References...304

5 XXVIII Table of contents 9. Moisture separation Introduction Moisture characteristics Simple methods for computation of the efficiency of the separation Cyclone separators Vane separators Velocity fields modeling in separators Kreith and Sonju solution for the decay of turbulent swirl in pipe Potential gas flow in vanes Trajectory of particles in a known continuum field CFD analyses of cyclones CFD analyses of vane separators Experiments BWR cyclones, PWR steam generator cyclones Other cyclone types Vane dryers Moisture separation in NPP with PWR s analyzed by three fluid models Separation efficiency of the specific cyclone design Efficiency of the specific vane separators design Uniformity of the flow passing the vane separators Efficiency of the condensate removal locally and integrally Nomenclature References Pipe networks Some basic definitions Pipes Axis in the space Diameters of pipe sections Reductions Elbows Creating a library of pipes Sub system network Discretization of pipes Knots The 1983-Interatome experiments Experiment Experiment Experiment Experiment Experiment Experiment Experiment References

6 Table of contents XXIX 11. Some auxiliary systems High pressure reduction station Gas release in research reactors piping Solubility of O 2, N 2 and H 2 under 1 bar pressure Some general remarks on the gas release- and absorption dynamics Gas release in the siphon safety pipe Radiolysis gases: generation, absorption and release Mixing in the water pool Computational analyses References Emergency condensers Introduction Simple mathematical illustration of the operation of the system Performance of the condenser as a function of the water level and pressure Condensate removal Core degradation Processes during the core degradation depending on the structure temperature Analytical tools for estimation of the core degradation References Melt-coolant interaction Melt-coolant interaction analysis for the boiling water reactor KARENA Interaction inside the guide tubes Melt-relocation through the lower core grid Side melt-relocation through the core barrel Late water injection Pressure increase due to the vapor generation at the surface of the melt pool Conditions for water penetration into melt Vessel integrity during the core relocation phase References Coolability of layers of molten reactor material Introduction Problem definition System of differential equations describing the process Simplifying assumptions Mass conservation Gas release and gas volume faction Viscous layer

7 XXX Table of contents Crust formation Melt energy conservation Buoyancy driven convection Film boiling Heat conducting structures Heat conduction through the structures Boundary conditions Oxide crust formation on colder heat conducting structures Metal layer Test case Oxide over metal Oxide besides metal Gravitational flooding of hot solid horizontal surface by water Simplifying assumptions Conservation of mass and momentum, scaling Eigen values, eigen vectors and canonical forms Steady state Nomenclature Nomenclature to Sect References External cooling of reactor vessels during severe accident Introduction State of the art Dry core melting scenario, melt relocation, wall attack, focusing effect Model assumptions and brief model description Molten pool behavior Two dimensional heat conduction through the vessel wall Boundary conditions Total heat flow from the pools into the vessel wall Vessel wall ablation Heat fluxes and crust formation Buoyancy convection Critical heat flux Application examples of the model The effect of vessel diameter The effect of the lower head radius The effect of the relocation time The effect of the mass of the internal structures Some important parameters characterizing the process Nomenclature References Appendix 1: Some geometrical relations

8 Table of contents XXXI 17. Thermo-physical properties for severe accident analysis Introduction Summary of the properties at the melting line at atmospheric pressure Approximation of the liquid state of melts Nomenclature References Uranium dioxide caloric and transport properties Solid Liquid Vapor References Zirconium dioxide Solid Liquid References Stainless steel Solid Liquid Vapor References Zirconium Solid Liquid References Aluminum Solid Liquid References Aluminum oxide, Al 2 O Solid Liquid References Silicon dioxide Solid Liquid References Iron oxide Solid Liquid References Molybdenum Solid Liquid References

9 XXXII Table of contents Boron oxide Solid Liquid References Reactor corium Liquid Solid References Sodium Some basic characteristics Liquid Vapor References Appendix Lead, bismuth and lead-bismuth eutectic alloy References Index