Audrius Graževičius doctoral dissertation defense

Author, Institution: Audrius Graževičius, Lithuanian Energy Institute

Dissertation title: Numerical investigation of two-component two-phase natural convection and thermal stratification phenomena

Science area, field of science: Technological Sciences – Energy and Power Engineering, T006

Defense of the dissertation: 2020-08-26, 14:00, Lithuanian Energy Institute (room – AK-330 a.), Breslaujos st. 3, Kaunas, Lithuania.

Scientific Supervisor: Assoc. Prof. Dr. Habil. Algirdas Kaliatka (Lithuanian Energy Institute, Technological Sciences, Energetics and Power Engineering – T006)

Dissertation Defence Board of Energetics and Power Engineering Science Field:

• Chairman – Dr. Egidijus Urbonavičius (Kaunas University of Technology, Technological Sciences, Energetics and Power Engineering, T006)
• Prof. Dr. Francesco D’Auria (University of Pisa, Italy, Technological Sciences, Energetics and Power Engineering, T006)
• Dr. Algis Džiugys (Lithuanian Energy Institute, Technological Sciences, Energetics and Power Engineering, T006)
• Dr. Raimondas Pabarčius (Lithuanian Energy Institute, Technological Sciences, Energetics and Power Engineering, T006)
• Assoc. Prof. Dr. Giedrė Streckienė (Vilnius Gediminas Technical University, Technological Sciences, Energetics and Power Engineering, T006)

The doctoral dissertation is available at the library of Kaunas University of Technology (K. Donelaičio St. 20, Kaunas, Lithuania) and in Lithuanian Energy Institute (Breslaujos St. 3, Kaunas, Lithuania).

Annotation:
It is important to understand processes, to predict steady or changing situations, and to manage potential or unexpected accidents when a powerful industrial unit is operated. Passive cooling systems that do not require an external power source during critical situations and accidents are being installed or designed in advanced industrial facilities in order to prevent or minimise the potential consequences of such accidents. This issue is particularly relevant in nuclear power plants because the potential consequences of accidents at these facilities can be severe. Natural convection and thermal stratification phenomena, which occur in cooling pools of passive systems are closely interrelated and their behavior affects the safety of the installations. Currently, there is a growing interest in modelling of these phenomena using CFD (Computational Fluid Dynamics) software, however, these phenomena are modelled using a lot of simplifications. There is no detailed and complex modelling methodology for these phenomena available today or it has not been published.

This dissertation introduces the methodology for modelling of two-component two-phase natural convection and thermal stratification phenomena in a cooling pool using CFD software. The methodology can be applied for modelling of these phenomena, which occurs in power or industrial installations (in the cooling pool of the passive system, in the spent nuclear fuel pool, in the nuclear or chemical reactor, etc.), facility or installation safety assessment, development of accident management methodology, etc.

• Summary of the dissertation (in Lithuanian)
• Dissertation