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Deformation and damage of tube bundle bends due to temperature
Michálková, Anežka ; Pernica, Marek (referee) ; Létal, Tomáš (advisor)
This master’s thesis deals with the problem of determining the thermal load of cross-flow tube bundle bends in steam superheater. Firstly, the theoretical basis of computational fluid dynamics and finite element method is introduced, and the possible methods of creep damage evaluation are presented as it was assumed that creep damage would be the most significant damage mechanism. The next part of this thesis describes simulations in ANSYS Fluent to determine values of heat transfer coefficients and ANSYS Mechanical to obtain temperature field and stresses. Based on the determined temperature field and stresses, a creep lifetime calculation according to ČSN EN 12952-4 is performed. Then creep design check for operating time 200 000 hours was carried out according to ČSN EN 13445-3. It was determined that in this case the tube bends are not the critical spot in comparison with the straight sections of tubes.
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Deformation and damage of tube bundle bends due to temperature
Michálková, Anežka ; Pernica, Marek (referee) ; Létal, Tomáš (advisor)
This master’s thesis deals with the problem of determining the thermal load of cross-flow tube bundle bends in steam superheater. Firstly, the theoretical basis of computational fluid dynamics and finite element method is introduced, and the possible methods of creep damage evaluation are presented as it was assumed that creep damage would be the most significant damage mechanism. The next part of this thesis describes simulations in ANSYS Fluent to determine values of heat transfer coefficients and ANSYS Mechanical to obtain temperature field and stresses. Based on the determined temperature field and stresses, a creep lifetime calculation according to ČSN EN 12952-4 is performed. Then creep design check for operating time 200 000 hours was carried out according to ČSN EN 13445-3. It was determined that in this case the tube bends are not the critical spot in comparison with the straight sections of tubes.
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Development of Creep Damage in Similar Weld Joints of P92 Steel Pipe
Král, Petr ; Sklenička, Václav ; Kuchařová, Květa ; Svobodová, M. ; Kvapilová, Marie ; Dvořák, Jiří
The microstructure and creep behaviour of the welded joints of P92 steel pipe were\ninvestigated in order to determine the influence of orbital heat welding technology on the creep\nresistance. Creep specimens were machined from the welded joints. Tensile creep tests of welded\njoints were performed at 873 K using different stresses. The microstructure of tested specimens was\ninvestigated by scanning electron microscope Tescan equipped with an electron-back scatter\ndiffraction. The creep results showed that the creep fracture strain of the welded joints decreases\nwith decreasing value of applied stress. Microstructure investigation showed that fracture behaviour\nof welded joints is influenced by an enhanced cavity formation at grain boundaries in the heataffected\nzone causing lower fracture ductility.
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