Improvement of the subcooled boiling model for low-pressure conditions in thermal-hydraulic codes

Hari, Sridhar; Hassan, Yassin A.

doi:10.1016/s0029-5493(02)00050-x

Cited by 86 publications

(3 citation statements)

References 9 publications

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“…The bubble departure diameter of the dispersed phase played a key role in the two-phase flow and heat transfer process and has a close relationship with the surface subcooling. Previously, the relationship between the surface subcooling and the bubble departure diameter was obtained from the experimental data [39][40][41][42] and empirical formula [43]. In this study, it can be seen from the numerical calculation that bubble departure diameter increased as surface subcooling increased.…”

Section: Characteristics Analysis Of Evaporation and Condensationmentioning

confidence: 71%

Simulation of the Vapor-Liquid Two-Phase Flow of Evaporation and Condensation

Hong-jie¹,

Zhang²,

Li³

et al. 2016

IJHT

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The heat pipe receiver with integrated high temperature latent thermal energy storage is one of the key components of Solar Dynamic Space Power System (SDPSS), among which the evaporation and condensation is the main heat transfer mode, a very complicated two-phase flow. However, research on the two-phase flow and heat transfer characteristics is an effective way to improve the system efficiency and reduce the system mass. So a two-dimensional physical model was built and the volume of fluid (VOF) technique was used to model the interaction between the two phases. The UDF (Users Define Function) was introduced to handle the mass source terms. In the study, the relationship between superheat, subcooling and wall heat flux were investigated. In addition, the flow pattern of bubbles in the tube was analyzed. Compared with the churn bubbles flow, the heat transfer coefficient of the bubbles flow was much higher. Bubble departure diameter increased as surface subcooling increased. The work in this paper lays a good foundation for the further research on the heat transfer characteristics of heat pipe receiver with integrated high temperature latent thermal energy storage.

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Section: Characteristics Analysis Of Evaporation and Condensationmentioning

confidence: 71%

Simulation of the Vapor-Liquid Two-Phase Flow of Evaporation and Condensation

Hong-jie¹,

Zhang²,

Li³

et al. 2016

IJHT

View full text Add to dashboard Cite

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“…Fi nally, the vapour gen er a tion rate per unit volume is cal cu lated [16] In the above model, the enthalpy cor re spond ing to the bub ble de par ture point, which is de noted as the crit i cal enthalpy, is es ti mated from…”

Section: Constitutive Models and Materialsmentioning

confidence: 99%

Simulation and analysis of a WWER-1000 reactor under normal and transient conditions

et al. 2016

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1 Nu clear Sci ence and Tech nol ogy Re search In sti tute, Atomic En ergy Or ga ni za tion of Iran, Teh ran, Iran 2 De part ment of Phys ics, Imam Hussein Uni ver sity, Teh ran, Iran 3 De part ment of Nu clear En gi neer ing, Sci ence and Re search Branch, Is lamic Azad Uni ver sity, Teh ran, Iran Sci en tific pa perAn ac cu rate anal y sis of the flow tran sient is very im por tant in safety eval u a tion of a nu clear power plant. In this study, anal y sis of a WWER-1000 re ac tor is in ves ti gated. In or der to perform this anal y sis, a model is de vel oped to sim u late the cou pled ki net ics and ther mal-hy draulics of the re ac tor with a sim ple and ac cu rate nu mer i cal al go rithm. For ther mal-hy drau lic calcu la tions, the four-equa tion drift-flux model is ap plied. Based on a multi-chan nel ap proach, core is di vided into some re gions. Each re gion has dif fer ent char ac ter is tics as rep re sented in a sin gle fuel pin with its as so ci ated cool ant chan nel. To ob tain the core power dis tri bu tion, point ki netic equa tions with dif fer ent feed back ef fects are uti lized. The ap pro pri ate ini tial and bound ary con di tions are con sid ered and two sit u a tions of de creas ing the cool ant flow rate in a pro tected and un pro tected core are an a lyzed. In ad di tion to anal y sis of nor mal op er a tion con di tion, a full range of ther mal-hy drau lic pa ram e ters is ob tained for tran sients too. Fi nally, the data ob tained from the model are com pared with the cal cu la tions con ducted us ing RELAP5/MOD3 code and Bushehr nu clear power plant data. It is shown that the model can pro vide ac cu rate pre dic tions for both steady-state and tran sient con di tions.

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“…Then ''pumping factor'' is defined by the ratio of heat flux due to bubble agitation and that causing vapor formation (Hari and Hassan, 2002) as:…”

Section: Liquid Phase Convectionmentioning

confidence: 99%

A two dimensional approach for temperature distribution in reactor lower head during severe accident

Cao

Liu

2015

Annals of Nuclear Energy

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a b s t r a c tIn order to evaluate the safety margin during a postulated severe accident, a module named ASAP-2D (Accident Simulation on Pressure vessel-2 Dimensional), which can be implemented into the severe accident simulation codes (such as ATHLET-CD), is developed in Shanghai Jiao Tong University. Based on two-dimensional spherical coordinates, heat conduction equation for transient state is solved implicitly. Together with solid vessel thickness, heat flux distribution and heat transfer coefficient at outer vessel surface are obtained. Heat transfer regime when critical heat flux has been exceeded (POST-CHF regime) could be simulated in the code, and the transition behavior of boiling crisis (from spatial and temporal points of view) can be predicted.The module is verified against a one-dimensional analytical solution with uniform heat flux distribution, and afterwards this module is applied to the benchmark illustrated in NUREG/CR-6849. Benchmark calculation indicates that maximum heat flux at outer surface of RPV could be around 20% lower than that of at inner surface due to two-dimensional heat conduction. Then a preliminary analysis is performed on the integrity of the reactor vessel for which the geometric parameters and boundary conditions are derived from a large scale advanced pressurized water reactor. Results indicate that heat flux remains lower than critical heat flux. Sensitivity analysis indicates that outer heat flux distribution is more sensitive to input heat flux distribution and the transition boiling correlation than mass flow rate in external reactor vessel cooling (ERVC) channel, and the correlation for molten vessel and ERVC coolant inlet temperature.According to the results achieved, the new developed module shows good applicability to simulate the pressure vessel behavior during melt pool formation. Thus it can be applied for the future study of the severe accidents relating to lower head integrity.

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Improvement of the subcooled boiling model for low-pressure conditions in thermal-hydraulic codes

Cited by 86 publications

References 9 publications

Simulation of the Vapor-Liquid Two-Phase Flow of Evaporation and Condensation

Simulation of the Vapor-Liquid Two-Phase Flow of Evaporation and Condensation

Simulation and analysis of a WWER-1000 reactor under normal and transient conditions

A two dimensional approach for temperature distribution in reactor lower head during severe accident

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