Boiling Heat Transfer in Liquid Metals

1988 ◽  
Vol 41 (3) ◽  
pp. 129-149 ◽  
Author(s):  
I. Michiyoshi
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Forced Convection ◽  
Boiling Heat Transfer ◽  
Liquid Metals ◽  
Pool Boiling ◽  
Two Phase ◽  
Sodium Potassium ◽  
Experimental Approaches ◽  
Flow Heat

This article presents the state-of-the-art review of boiling heat transfer in various liquid metals paying attention to research papers published in the last 15 years. Particular emphasis is laid on the incipient boiling superheat, diagnosis of natural and forced convection boiling, nucleate pool boiling heat transfer in mercury, sodium, potassium, NaK, lithium, and so on at sub- and near atmospheric pressure, effect of liquid level on liquid metal boiling, subcooling effect due to hydrostatic head on liquid metal boiling, effect of magnetic field on liquid metal boiling, pool boiling crisis under various conditions and intermittent boiling of liquid metal, two-phase flow heat transfer, and natural and forced convection film boiling in saturated and subcooled liquid metals. In conclusion, there still remain some ambiguous and unsolved problems which are pointed out in this article. Further studies are of course required to clarify and solve them in future with both theoretical and experimental approaches.

Pool Boiling Heat Transfer Characteristics of HFO-1234yf With and Without Microporous-Enhanced Surfaces

2011 ◽  
Author(s):  
Gilberto Moreno ◽  
Sreekant Narumanchi ◽  
Charles King
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Fundamental Study ◽  
Heat Transfer Coefficients ◽  
Hfc 134A ◽  
Lower Heat

This fundamental study characterizes the pool boiling performance of a new refrigerant, HFO-1234yf (hydrofluoroolefin 2,3,3,3-tetrafluoropropene). The similarities in thermophysical properties with HFC-134a and low global warming potential make HFO-1234yf the prospective next generation refrigerant in automotive air-conditioning systems. This study examines the possibility of using this refrigerant for two-phase cooling of hybrid and electric vehicle power electronic components. Pool boiling experiments were conducted with HFO-1234yf and HFC-134a at system pressures ranging from 0.7 to 1.7 MPa using horizontally oriented 1 cm2 heat sources. Results show that the boiling heat transfer coefficients of HFO-1234yf and HFC-134a are nearly identical at lower heat fluxes. HFO-1234yf yielded lower heat transfer coefficients at higher heat fluxes and lower critical heat flux (CHF) as compared with HFC-134a. To enhance boiling heat transfer, a copper microporous coating was applied to the test surfaces. The coating provided enhancement to both the boiling heat transfer coefficients and CHF, for both refrigerants, at all tested pressures. Increasing pressure decreases the level of heat transfer coefficient enhancements while increasing the level of CHF enhancements.

Numerical Investigation on Pool Boiling Over a Vertical Tube Coupled With In-Tube Condensation

2019 ◽  
Author(s):  
Shuai Ren ◽  
Wenzhong Zhou
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Boiling Heat Transfer ◽  
Power Plants ◽  
Pool Boiling ◽  
Heat Removal ◽  
Vertical Tube ◽  
Two Phase ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Abstract Pool boiling and in-tube condensation phenomena have been investigated intensively during the past decades, due to the superior heat transfer capacity of the phase change process. In passive heat removal heat exchangers of nuclear power plants, the two phase-change phenomena usually occur simultaneously on both sides of the tube wall to achieve the maximum heat transfer efficiency. However, the studies on the effects of in-tube condensation on external pool boiling heat transfer are very limited, especially in numerical computation aspect. In the present study, the saturated pooling boiling over a vertical tube under the influences of in-tube steam condensation is investigated numerically. The Volume of Fluid (VOF) interface tracking method is employed based on the 2D axisymmetric Euler-Euler multiphase frame. The phase change model combining with a mathematical smoothing algorithm and a temporal relaxation procedure has been implemented into CFD platform by user defined functions (UDFs). The two-phase flow pattern and bubble behavior have been analyzed. The effects of inlet steam mass flow rate on boiling heat transfer are discussed.

Validation of TRACE in the Field of Liquid Metal Heat Transfer

2014 ◽  
Author(s):  
Wadim Jaeger ◽  
Wolfgang Hering ◽  
Nerea Diez de los Rios ◽  
Antonio Gonzalez
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Data Base ◽  
Forced Convection ◽  
Liquid Metals ◽  
Metal Flow ◽  
Lead Alloy ◽  
Ongoing Task ◽  
Rod Bundles ◽  
Liquid Metal Flow

The validation of system codes like TRACE is an ongoing task especially in areas with limited or almost no application like liquid metal flow. Therefore, extensive validation efforts are necessary to increase the confidence in the code predictions. TRACE has been successfully validated and applied to lead-alloy cooled systems. The results gained with lead-alloy coolants could be extrapolated to other liquid metals with the necessary care. Nevertheless, dedicated investigations with the different liquid metals are mandatory to confirm the extrapolations. In the present case, the validation work focuses on liquid metal heat transfer in pipes and rod bundles under forced convection. To take advantage of a greater data base, several liquid metals have been implemented into the code. In addition, new coolants allow supporting analysis of liquid metals loops which are in the design or construction stage. Concerning the validation, several experiments have been found, conducted by other investigators, which are modeled with the modified TRACE version. The results indicate that the chosen heat transfer models for pipe and bundle flow are applicable. In case of deviations, physical sound reasons can be provided to explain them.

Design and Performance of Two-Phase Flow Heat Transfer Experiment Platform Using R134a as Working Fluid

2010 ◽  
Author(s):  
Chang-Nian Chen ◽  
Ji-Tian Han ◽  
Li Shao ◽  
Tien-Chien Jen ◽  
Yi-Hsin Yen
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Two Phase Flow ◽  
Working Fluid ◽  
Phase Flow ◽  
Heat Transfer Characteristics ◽  
Transfer Experiment ◽  
Two Phase ◽  
Experiment Platform ◽  
Flow Heat

A two-phase flow heat transfer experiment platform using alternative refrigerant R134a as working fluid was designed and built to investigate the characteristics of two-phase flow heat transfer. It was primarily made up of circle power, heating/cooling sources, parallel test sections, accumulator and data acquisition system. The working loop was designed for performance pressure of 1.6 MPa and temperature of 200°C, preheated section power of 24 V × 300 A and test section of 60 V × 500 A. The refrigeration chilling unit had a maximum output of 50 kW. The preheated and test section were designed as horizontal helically-coiled tubes, and a visual reservoir made of electric melting-quartz glass was designed to observe flow patterns intuitively. Technology and methods related to fluid and mechanics were discussed in this paper including the aspects of materials and welding, sealing and heat preservation, special machining and accessories installation etc. Pressure testing, heat balance testing, heat transfer characteristics experiments were performed under various conditions to analyze the usability and stability of this platform. Test results showed that the leak ratio was no more than 250 Pa/h at 2.0 MPa and the heat loss of the system wrapped with PEF materials was less than 5%. Under the conditions of pressures of 0.30–0.95 MPa, mass fluxes of 120–620 kg/m2s, inlet qualities of −0.08–0.38 and heated power of 0.45–1.30 kW, R134a two-phase flow boiling heat transfer characteristics were investigated and discussed in detail. This platform can be used for studying the characteristics of two-phase flow pressure drop, boiling heat transfer and fluid-to-fluid modeling technique etc.

scholarly journals Enhanced pool boiling heat transfer on soft liquid metal surface

2021 ◽  
Vol 70 (13) ◽  
pp. 134703-134703
Author(s):  
Cao Chun-Lei ◽  
◽  
He Xiao-Tian ◽  
Ma Xiao-Jing ◽  
Xu Jin-Liang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Metal Surface ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Pool Boiling Heat Transfer ◽  
Liquid Metal Surface

scholarly journals Experimental Approaches to Measurement of Vapor Quality of Two-Phase Flow Boiling

2020 ◽  
Author(s):  
Mehdi Kabirnajafi ◽  
Jiajun Xu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Phase Flow ◽  
Vapor Quality ◽  
Two Phase ◽  
Thermal Boundary Conditions ◽  
Flow Boiling Heat Transfer ◽  
Experimental Approaches

Vapor quality is one of the crucial parameters substantially affecting the flow boiling heat transfer coefficient. Hence, the reliability and accuracy of vapor quality measurements is of a great significance to accurately investigating the effect of vapor quality on the local flow boiling heat transfer coefficients. In the present study, various experimental approaches are represented to measure and control local vapor quality for flow boiling tests. Experimental approaches are classified based on the type of thermal boundary conditions imposed on the tube wall, that is, known constant wall heat flux and constant wall temperature (unknown variable wall heat flux). In addition, in-situ techniques are also investigated to measure local vapor quality regardless of the governing thermal boundary conditions within two-phase flow experiments. Finally, the experimental methodologies are compared based on their level of reliability and accuracy in measurement, costliness and affordability, and simplicity in execution to address their potential merits and demerits.

The Determination of Forced-Convection Surface-Boiling Heat Transfer

1964 ◽  
Vol 86 (3) ◽  
pp. 365-372 ◽  
Author(s):  
A. E. Bergles ◽  
W. M. Rohsenow
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Experimental Results ◽  
Boiling Curve ◽  
Wall Superheat ◽  
Good Agreement

The characteristics of the boiling curve for forced-convection surface boiling are examined in detail. In the region of low wall superheat, the heat transfer can be predicted by available correlations for forced convection. An analysis is presented for the inception of first significant boiling. Experimental results are in good agreement with analytical predictions. Pool-boiling data were taken under saturated and subcooled conditions for surfaces similar to those used in forced-convection surface boiling. These data indicate that the curves for forced-convection surface boiling cannot be based on data for saturated pool boiling but must rather be based on actual forced-convection data.

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