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Thermohydraulic Analysis of High Temperature Gas-Cooled Reactors Using Porous Media Approach

Tabatabai Ghomsheh, Isar | 2015

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 55748 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Nouri Borojerdi, Ali
  7. Abstract:
  8. High temperature modular reactors (HTR) are the most likely next generation reactors that will meet future energy needs. Their inherent safety is the most attractive feature of this type of reactors, and along with that, we can mention the ease of their design, operation and maintenance. Since the reactor is safe in the event of an accident, without activating any external source of security, this reactor is considered intrinsically safe. Despite this inherent property, the reactor is only affected by its physical characteristics, and therefore, many dangerous situations are prevented.The inherent safety feature of this reactor is completely dependent on its proper design. The power density in the core, the radius and height of the core, the properties of the materials used, and the shape of their placement should be selected so that the heat caused by the decay produced in the core, in any event, can be transferred through natural heat transfer phenomenon without assistance. Any external auxiliary source should be transferred to the surrounding environment. In addition, the reactants entering the core must be limited so that the fuel temperature increase corresponding to them is always lower than the design fuel temperature limit. In addition to the inherent safety feature, the reactor must be designed to be economically competitive. The aim of this research is to write a two-dimensional program that can be executed quickly so that it can be used for heat transfer analysis and designing and solving safety issues of modular high-temperature reactors. This program should be generally usable for all types of modular HTRs (such as pellet and block reactors) and operating conditions with forced displacement (normal reactor operation) in addition to accident conditions in which heat is removed by thermal conduction and natural displacement. occurs, they should be covered in it. In general, we are trying to get a quick analysis that can provide us with enough insight for informed decision-making, so that we don't have to spend a long time to get to deep and detailed analyzes with large CFD models. .In this research, the porous medium approach has been used. The equations of conservation of mass and energy and the equation of conservation of momentum for the cooling gas have been solved and along with it, the energy equation for the solid has also been solved. Also, a set of appropriate combined equations (such as solid effective thermal conductivity, pressure drop, heat transfer coefficient, etc.) is used and the finite volume method is also used for spatial discretization. The ability of the program to simulate pellet reactors and fuel blocks, for normal working conditions as well as accident conditions with pressure drop or without pressure drop, has been shown by calculating two benchmark problems, and the results show good consistency
  9. Keywords:
  10. Porous Media ; Control Volume ; Heat Transfer ; Numerical Simulation ; Gas Cooled Reactor ; High Themprature Gas-Cooled Reactor (HTGR) ; Thermohydraulic Analysis

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