Study of Thermal Influence on Tubes Due to Sodium-Water Reactions in LMFBR Steam Generator

2004 ◽  
Author(s):  
Hirotsugu Hamada ◽  
Akikazu Kurihara ◽  
Masahiro Nishimura
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Steam Generator ◽  
Outer Surface ◽  
Single Phase ◽  
Tube Wall ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics ◽  
Thermal Influence

A study of thermal influence on heat-transfer tubes in sodium-water reactions is carried out to evaluate the tube rupture due to overheating in the water leak accident of an LMFBR steam generator (SG). By assuming the sodium-water reaction jet to be a two-phase flow that consists of sodium and hydrogen, the heat-transfer characteristics are examined and a simple model of effective heat-transfer coefficient (HTC) is proposed for the safety evaluation of the SG. Comparison of the model with experimental data leads to the following conclusions: An upper limit exists in the HTC between reaction jet and tube wall, and it is equivalent in approximation to the HTC of single-phase sodium flow. The HTC can be written in simple form as functions of the HTC of single-phase sodium flow, void fraction and temperatures of sodium, hydrogen and tube wall. Hydrogen provides negligible heating effect, so that the apparent HTC would decrease with increase of the hydrogen temperature that can readily surpass that of sodium. The outer-surface temperature of tube wall would not rise so high beyond the temperature of sodium that is excellent in heat-transfer characteristics, even if tube wall is exposed to the high-temperature hydrogen. The transient heat conduction analysis with the mean value of the data can appropriately evaluate the outer-surface temperature of tube wall by the metallographic observation, while the analysis with the maximum value can conservatively evaluate the tube wall temperature.

Theoretical and Experimental Research on the Single-Phase and Incipient Boiling Heat Transfer of Liquid Metal Sodium

2017 ◽  
Author(s):  
Dalin Zhang ◽  
Jing Chen ◽  
Ping Song ◽  
Shibao Wang ◽  
Xin'an Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Experimental Research ◽  
Single Phase ◽  
Nuclear Reactor ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics

Sodium-cooled Fast Reactor (SFR) is the most promising reactor among the six Gen-IV nuclear reactor systems. The coolant of SFR is liquid metal which has very different heat transfer characteristics from conventional fluids. The study on heat transfer characteristics of the liquid metal sodium at single-phase and two-phase has not only great academic but also application meanings for SFRs design and safety analysis. Xi’an Jiaotong University (XJTU) performed comprehensive studies from the theoretical and experimental aspects. In the theoretical studies, the main focuses are paid on the sodium single-phase heat transfer flowing in rod bundles, incipient boiling, two-phase thermal-hydraulic and critical heat flux (CHF). The experimental research on the flow and heat transfer characteristics of sodium in annuli is performed on XJTU single-phase sodium loop and two-phase boiling sodium loop, in which the single-phase friction and Nu correlations, the incipient boiling superheat (IBS) correlations, the two-phase friction multiplier factor and the heat transfer coefficient of sodium boiling are obtained. In this paper, the established theoretical models and the experimental studies for the single-phase heat transfer and the IBS in the annuli or the pin bundles are presented. The theoretical models are validated by the experimental data, and the comparison shows good agreement.

Evaporation of Single Drops of n-Pentane/n-Hexane Mixtures in Water

1992 ◽  
Vol 114 (4) ◽  
pp. 965-971 ◽  
Author(s):  
H. Shimaoka ◽  
Y. H. Mori
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Vapor Bubble ◽  
Experimental Results ◽  
Rise Velocity ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics ◽  
Preceding Work ◽  
Liquid Vapor

The evaporation of isolated drops (2.1−3.0 mm diameter) of nonazeotropic n-pentane/n-hexane mixtures in the medium of water was observed under pressures of 0.11−0.46 MPa and temperature differences up to 27 K. The mole fractions of n-pentane, x, in the mixtures were set at 0.9, 0.5, 0.1, and 0, to be completed by the condition x = 1 set in a preceding work (Shimaoka and Mori, 1990). Experimental results are presented in terms of the instantaneous rise velocity of, and an expression of instantaneous heat transfer to, each drop evaporating and thereby transforming into a liquid/vapor two-phase bubble and finally into a vapor bubble. The dependencies of the heat transfer characteristics on the pressure, the temperature difference, and x are discussed.

scholarly journals Modeling Study on Heat Transfer in Marangoni Dropwise Condensation for Ethanol-Water Mixture Vapors

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6726
Author(s):  
Jinshi Wang ◽  
Ziqiang Ma ◽  
Yong Li ◽  
Weiqi Liu ◽  
Gen Li
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Temperature Difference ◽  
Diffusion Layer ◽  
Water Mixture ◽  
Dropwise Condensation ◽  
Heat Transfer Characteristics ◽  
Vapor Diffusion ◽  
Transfer Characteristics ◽  
Condensate Layer

In this paper, a model was developed to predict the heat transfer characteristics of Marangoni dropwise condensation. In accordance with the feature of Marangoni condensation, condensation was treated as dropwise condensation of mixture vapors. The condensation space was divided into two parts: the vapor diffusion layer and the condensate layer. For the condensate layer, the classical heat transfer calculation method of dropwise condensation was imitated to obtain the heat transfer characteristics. For the vapor diffusion layer, the heat transfer characteristics were achieved by solving the conservation equations. These heat transfer characteristics were coupled through the conjunct boundary, which was the vapor-liquid interface. The model was applied to the condensation of water-ethanol mixture vapors. A comparison with the existing experimental data showed that the developed model could basically reflect the influences of vapor-to-surface temperature difference, vapor concentration, vapor pressure, and vapor velocity on heat transfer characteristic of Marangoni condensation. Results showed that some differences existed between the calculation results and experimental results, but the prediction deviation of the model could be acceptable in the range of vapor-to-surface temperature difference where the condensation heat transfer coefficients reached peak values.

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