Cold wall effects of control rod guide tubes and experimental flow channel walls
| Autor: | Hongmei Lyu, Tianze Li, Bao-Wen Yang |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Mass flux
Nuclear and High Energy Physics Materials science 020209 energy Mechanical Engineering Control rod Flow (psychology) Pressurized water reactor 02 engineering and technology Mechanics 01 natural sciences 010305 fluids & plasmas law.invention Nuclear Energy and Engineering law Bundle Boiling 0103 physical sciences Heat transfer 0202 electrical engineering electronic engineering information engineering Working fluid General Materials Science Safety Risk Reliability and Quality Waste Management and Disposal |
| Zdroj: | Nuclear Engineering and Design. 356:110325 |
| ISSN: | 0029-5493 |
| DOI: | 10.1016/j.nucengdes.2019.110325 |
| Popis: | In rod bundle experiments, coarse flow housing walls are used to provide flow boundaries for the working fluid. In the PWR (Pressurized Water Reactor) reactor core, the guide tubes are needed to provide channels for control rods. The non-prototypical flow channel walls and guide tubes have similar cold wall effects on the thermal and hydraulic conditions of the surrounding flow channels. They might influence the local temperature, quality and mass flux distributions, which could have potential impacts on local mass and heat transfer characteristics. For example, when the flow resistance in the boiling hot channel increases due to steam generation, the adjacent cold channels around the guide tube can bypass the coolant and lead to the escalation of flow starvation in the steaming hot channel, which might ultimately lead to the early occurrence of a boiling crisis. In the rod bundle experiment, in order to ensure the representation of the CHF experiments, it is important to minimize the effects of the non-prototypical flow channel walls. In this paper, the wall effects of flow channel walls in a typical 5 × 5 rod bundle CHF test configuration have been minimized by optimizing the rod-to-wall gap (the gap between the outer rod wall and the channel inner wall design) through analytical analysis, CFD modeling and subchannel code calculation. This study concluded that the proper rod-to-wall gaps in the thermal field are often different from that in the hydraulic field. Therefore reasonable weight factors have been proposed to incorporate different impacts from these two fields. In order to determine proper design of rod-to-wall gap, the average temperature criterion, average mass flux criterion and maximum wall temperature criterion have been examined. Similarly, the cold wall effects of guide tube have been investigated using the theoretical model developed for the thermal field. |
| Databáze: | OpenAIRE |
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