ISSN Online: 2377-424X
International Heat Transfer Conference 12
Numerical and experimental study of thermal stratification of coolant in nuclear power plant pipe-lines
Abstrakt
Phenomena of coolant thermal stratification belong to the complicated and insufficiently investigated division of
technical thermohydraulics. Thermal fatigue due to big and sharp temperature differences, which are inherent to
a thermal stratification, causes a number of serious problems in the design of any mechanical component. Study
of temperature stratification of coolant flow in piping is important for safety and reliability of nuclear power
plants (NPP) (Schulz, 1998), (Opanasenko, 1998). A number of incidents at NPP with different pressurized and
boiling water reactors made this problem very actual. The set of experimental and numerical results for cold
pipeline model of WWER reactor (russian pressurized water type reactor) are presented. Appearance of thermal
stratification conditions due to different temperatures in separate pipelines arising from emergency core cooling
system is considered. The critical Froude number (Fr) at which the thermal stratification occurs is determined,
hydrodynamics and thermal flow characteristics, its stability are investigated and dependences for hot fluid
wedge are obtained. Numerical simulation of mixed convection is performed on the base of the Navier-Stokes
equations. Implicit numerical method is employed (Artemyev, 1998). Results of numerical predictions and comparison
with experimental data are presented.