Thermal-hydraulic phenomena and heat removal performance of a passive containment cooling system according to exit loss coefficient
2
조회
0
다운로드
0
인용
0
참고문헌
키워드
초록
The natural circulation system has been widely studied for use in various applications because of its inherent advantage. However, it has a key weakness called flow instability that makes the system unstable. Through massive previous research, the mechanisms of flow instability were analyzed, but there was an ambiguous aspect related to the effect of experimental parameters on the phenomenon. Particularly, there has been no report on the heat transfer performance of the system when flow instability phenomena were present. In this study, thermal-hydraulic phenomena of a two-phase natural circulation system that functions as a passive containment cooling system (PCCS) was investigated according to experimental parameters, namely, the temperature boundary (120–158 ◦C) and exit loss coefficient (0–34.5) under atmospheric pressure conditions. The experimental results showed five different flow types in the loop. The flow modes that occurred by the interaction between flashing and boiling were classified by referring to the mass flow rate, void fraction, and visualization data. The system was more unstable when the temperature boundary conditions increased, but it was more stable when the exit loss coefficient increased. These results have only been confirmed in our research. The reason for the results is that the flow conditions are located on the boundary between Density Wave Oscillation I and the stable flow region, and that boundary does not have clear criteria. In addition, comparing the heat transfer performance of a system by heat rate can confirm the effect of flow instability on the thermal performance of the passive cooling system. As a result, the high exit loss coefficient stabilizes the system better than the low case and has similar heat removal performance.
Abstract
The natural circulation system has been widely studied for use in various applications because of its inherent advantage. However, it has a key weakness called flow instability that makes the system unstable. Through massive previous research, the mechanisms of flow instability were analyzed, but there was an ambiguous aspect related to the effect of experimental parameters on the phenomenon. Particularly, there has been no report on the heat transfer performance of the system when flow instability phenomena were present. In this study, thermal-hydraulic phenomena of a two-phase natural circulation system that functions as a passive containment cooling system (PCCS) was investigated according to experimental parameters, namely, the temperature boundary (120–158 ◦C) and exit loss coefficient (0–34.5) under atmospheric pressure conditions. The experimental results showed five different flow types in the loop. The flow modes that occurred by the interaction between flashing and boiling were classified by referring to the mass flow rate, void fraction, and visualization data. The system was more unstable when the temperature boundary conditions increased, but it was more stable when the exit loss coefficient increased. These results have only been confirmed in our research. The reason for the results is that the flow conditions are located on the boundary between Density Wave Oscillation I and the stable flow region, and that boundary does not have clear criteria. In addition, comparing the heat transfer performance of a system by heat rate can confirm the effect of flow instability on the thermal performance of the passive cooling system. As a result, the high exit loss coefficient stabilizes the system better than the low case and has similar heat removal performance.
참고문헌 (28)
- W. He, "Comparative experiment study on photovoltaic and thermal solar system under natural circulation of water", Appl. Therm. Eng, 31(16), pp.3369~3376 (2011)
- W. He, "Hybrid photovoltaic and thermal solar-collector designed for natural circulation of water", Appl. Energy, 83(3), pp.199~210 (2006)
- T. Van der Hagen, "The low-power low-pressure flow resonance in a natural circulation cooled boiling water reactor", Nucl. Eng. Des, 177(1–3), pp.229~238 (1997)
- C. P. Marcel, "An experimental parametric study on natural circulation BWRs stability", Nucl. Eng. Des, 318, pp.135~146 (2017)
- S. Arneth, "Characteristics of thermosiphon reboilers", Int. J. Therm. Sci, 40(4), pp.385~391 (2001)
- J. Luitjens, "Mechanistic CHF modeling for natural circulation applications in SMR", Nucl. Eng. Des, 310, pp.604~611 (2016)
- S. Wang, "Experimental investigation on flashinginduced flow instability in a natural circulation scaled-down test facility", Ann. Nucl. Energy, 171, pp.109023~ (2022)
- M. Kawakubo, "An experimental study on the cooling characteristics of passive containment cooling systems", Journal of nuclear science and technology, 46(4), pp.339~345 (2009)
- J. Boure, "Review of two-phase flow instability", Nucl. Eng. Des, 25(2), pp.165~192 (1973)
- S. Kakaç, "A review of two-phase flow dynamic instabilities in tube boiling systems", Int. J. Heat Mass Tran, 51(3–4), pp.399~433 (2008)
- S. Jiang, "Experimental simulation study on start-up of the 5MW nuclear heating reactor", Nucl. Eng. Des, 158(1), pp.111~123 (1995)
- M. Aritomi, "Fundamental study on thermo-hydraulics during start-up in natural circulation boiling water reactors,(I)thermo-hydraulic instabilities", J. Nucl. Sci. Technol, 29(7), pp.631~641 (1992)
- M. Furuya, "Flashing-induced density wave oscillations in a natural circulation BWR—mechanism of instability and stability map", Nucl. Eng. Des, 235(15), pp.1557~1569 (2005)
- S. -K. Yang, "Stability of flashing-driven natural circulation in a passive moderator cooling system for Canadian SCWR", Nucl. Eng. Des, 276, pp.259~276 (2014)
- H. Liu, "An experimental investigation of a passive cooling unit for nuclear plant containment", Nucl. Eng. Des, 199(3), pp.243~255 (2000)
- Flow characteristics in an open two-phase natural circulation loop, in: International Conference on Nuclear Engineering, "X. Hou", American Society of Mechanical Engineers, ~, pp.V02BT09A004 (2014)
- X. Hou, "An investigation on flashing instability induced water hammer in an open natural circulation system", Prog. Nucl. Energy, 93, pp.418~430 (2016)
- X. Hou, "Experimental and analytical investigation on the flow characteristics in an open natural circulation system", Appl. Therm. Eng, 124, pp.673~687 (2017)
- X. Hou, "A study on the steady-state flow behavior of the flashing-driven open natural circulation system", Appl. Therm. Eng, 182, pp.115903~ (2021)
- J. Bang, "Comparisons of performance and operation characteristics for closed-and open-loop passive containment cooling system design", Nucl. Eng. Technol, 53(8), pp.2499~2508 (2021)
- K. M. Kim, "Analysis of natural circulation behaviors and flow instabilities of passive containment cooling system design for advanced PWR using MARS-KS code", Int. J. Heat Mass Tran, 147, pp.118982~ (2020)
- S. T. Lim, "Experimental investigation of two-phase natural circulation loop as passive containment cooling system", Nucl. Eng. Technol, 53(12), pp.3918~3929 (2021)
- D. W. Green, "Perry’s Chemical Engineers’ Handbook" (2019), McGraw-Hill Education
- E. W. Lemmon, "Thermodynamic properties of air and mixtures of nitrogen, argon, and oxygen from 60 to 2000 K at pressures to 2000 MPa", J. Phys. Chem. Ref. Data, 29(3), pp.331~385 (2000)
- K. Woo, "Experimental and Analytical Study of Stability Characteristics of Natural Circulation Boiling Water Reactors during Startup Transient", pp.2008
- F. -S. Wang, "Thermal and stability analysis of a two-phase natural circulation loop", Nucl. Sci. Eng, 117(1), pp.33~46 (1994)
- K. Cheng, "Experimental investigation on flow characteristics of pressure drop oscillations in a closed natural circulation loop", Int. J. Heat Mass Tran, 122, pp.1162~1171 (2018)
- I. S. Kyung, "Experimental observations on flow characteristics in an open two-phase natural circulation loop", Nucl. Eng. Des, 150(1), pp.163~176 (1994)