scholarly journals Heat Transfer During Film Condensation of a Liquid Metal Vapor

1966 ◽  
Vol 88 (1) ◽  
pp. 19-27 ◽  
Author(s):  
S. P. Sukhatme ◽  
W. M. Rohsenow
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Liquid Metals ◽  
Metal Vapor ◽  
Accommodation Coefficient ◽  
Film Condensation ◽  
Nickel Surface ◽  
Interfacial Resistance ◽  
Noncondensable Gases ◽  
Liquid Vapor

The object of this investigation is to resolve the discrepancy between theory and experiment for the case of heat transfer during film condensation of liquid metal vapors. Calculations from kinetic theory show that with liquid metals a significant thermal resistance can exist at the liquid-vapor interface. This resistance increases with decreasing vapor pressure and is dependent on the value of an accommodation coefficient, named the “condensation coefficient” in this case. Experimental work verifying this hypothesis of a liquid-vapor interfacial resistance is presented here for mercury condensing at low pressures in the absence of noncondensable gases on a vertical nickel surface.

Convective Cooling of Compact Electronic Devices via Liquid Metals with Low Melting Points

2021 ◽  
Author(s):  
Guilin Liu ◽  
Jing Liu
Keyword(s):  
Heat Transfer ◽  
Melting Point ◽  
Liquid Metal ◽  
High Performance ◽  
Flow Resistance ◽  
Heat Dissipation ◽  
Liquid Metals ◽  
Electronic Devices ◽  
Convective Cooling ◽  
Heat Exchanger Design

Abstract The increasingly high power density of today's electronic devices requires the cooling techniques to produce highly effective heat dissipation performance with as little sacrifice as possible to the system compactness. Among the currently available thermal management schemes, the convective liquid metal cooling provides considerably high performance due to their unique thermal properties. This paper firstly reviews the studies on convective cooling using low-melting-point metals published in the past few decades. A group of equations for the thermophysical properties of In-Ga-Sn eutectic alloy is then documented by rigorous literature examination, following by a section of correlations for the heat transfer and flow resistance calculation to partially facilitate the designing work at the current stage. The urgent need to investigate the heat transfer and flow resistance of forced convection of low-melting-point metals in small/mini-channels, typical in compact electronic devices, is carefully argued. Some special aspects pertaining to the practical application of this cooling technique, including the entrance effect, mixed convection, and compact liquid metal heat exchanger design, are also discussed. Finally, future challenges and prospects are outlined.

Development of High Temperature Liquid Metal Heat Transfer Fluids for CSP Applications

2014 ◽  
Author(s):  
Gopinath R. Warrier ◽  
Y. Sungtaek Ju ◽  
Jan Schroers ◽  
Mark Asta ◽  
Peter Hosemann
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Liquid Metal ◽  
Liquid Metals ◽  
Research Effort ◽  
Structural Materials ◽  
Forced Flow ◽  
Oxygen Control ◽  
Ongoing Research ◽  
Heat Transfer Fluids

In response to the DOE Sunshot Initiative to develop low-cost, high efficiency CSP systems, UCLA is leading a multi-university research effort to develop new high temperature heat transfer fluids capable of stable operation at 800°C and above. Due to their operating temperature range, desirable heat transfer properties and very low vapor pressure, liquid metals were chosen as the heat transfer fluid. An overview of the ongoing research effort is presented. Development of new liquid metal coolants begins with identification of suitable candidate metals and their alloys. Initial selection of candidate metals was based on such parameters as melting temperature, cost, toxicity, stability/reactivity Combinatorial sputtering of the down selected candidate metals is used to fabricate large compositional spaces (∼ 800), which are then characterized using high-throughput techniques (e.g., X-ray diffraction). Massively parallel optical methods are used to determine melting temperatures. Thermochemical modeling is also performed concurrently to compliment the experimental efforts and identify candidate multicomponent alloy systems that best match the targeted properties. The modeling effort makes use of available thermodynamic databases, the computational thermodynamic CALPHAD framework and molecular-dynamics simulations of molten alloys. Refinement of available thermodynamics models are performed by comparison with available experimental data. Characterizing corrosion in structural materials such as steels, when using liquid metals, and strategies to mitigate them are an integral part of this study. The corrosion mitigation strategy we have adopted is based on the formation of stable oxide layers on the structural metal surface which prevents further corrosion. As such oxygen control is crucial in such liquid metal systems. Liquid metal enhanced creep and embrittlement in commonly used structural materials are also being investigated. Experiments with oxygen control are ongoing to evaluate what structural materials can be used with liquid metals. Characterization of the heat transfer during forced flow is another key component of the study. Both experiments and modeling efforts have been initiated. Key results from experiments and modeling performed over the last year are highlighted and discussed.

Main Results of Na-K Alloy Boiling Investigation

2002 ◽  
Author(s):  
G. A. Sorokin ◽  
G. P. Bogoslovskaya ◽  
E. F. Ivanov ◽  
A. P. Sorokin
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Modeling ◽  
Liquid Metal ◽  
Critical Heat Flux ◽  
Liquid Metals ◽  
Operating Conditions ◽  
Coolant Temperature ◽  
Low Velocity ◽  
Experimental Conditions

Boiling experiments on eutectic sodium-potassium alloy in the model of fast reactor subassembly under conditions of low-velocity circulation carried out at the IPPE call for further investigations into numerical modeling of the process. The paper presents analysis of pin bundle liquid metal boiling, stages of the process, its characteristics (wall temperature, coolant temperature, flow rate. pressure void fraction and others), that allowed the pattern map to be drawn. The problem of conversion of the data gained in Na-K mock-up experiments to in-pile sodium reactor operating conditions is analyzed here, as well as thermodynamic similarity of liquid metal coolants and eutectic Na-K alloy. Data on bundle boiling in Na-K are presented in comparison with those in different liquid metals. Analysis of data on liquid metal heat transfer in cases of pool boiling, boiling in tubes, in slots, and in pin bundles, as well as data on critical heat flux in tubes was performed and discussed in the paper. The relationship for calculation of critical heat flux in liquid metal derived by the authors is presented. Results of numerical modeling of liquid metal boiling heat transfer during accident cooling of reactor core applied to experimental conditions of going from forced to natural circulation are presented, too.

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.

scholarly journals NGNP Process Heat Utilization: Liquid Metal Phase Change Heat Exchanger

2008 ◽  
Author(s):  
Piyush Sabharwall ◽  
Mike Patterson ◽  
Vivek Utgikar ◽  
Fred Gunnerson
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Liquid Metal ◽  
Phase Change ◽  
Heat Exchangers ◽  
Liquid Metals ◽  
Compact Heat Exchangers ◽  
Process Heat

One key long-standing issue that must be overcome to fully realize the successful growth of nuclear power is to determine other benefits of nuclear energy apart from meeting the electricity demands. The Next Generation Nuclear Plant (NGNP) will most likely be producing electricity and heat for the production of hydrogen and/or oil retrieval from oil sands and oil shale to help in our national pursuit of energy independence. For nuclear process heat to be utilized, intermediate heat exchange is required to transfer heat from the NGNP to the hydrogen plant or oil recovery field in the most efficient way possible. Development of nuclear reactor-process heat technology has intensified the interest in liquid metals as heat transfer media because of their ideal transport properties. Liquid metal heat exchangers are not new in practical applications. An important rationale for considering liquid metals as the working fluid is because of the higher convective heat transfer coefficient. This explains the interest in liquid metals as coolant for intermediate heat exchange from NGNP. The production of electric power at higher efficiency via the Brayton Cycle, and hydrogen production, requires both heat at higher temperatures and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. Compact heat exchangers maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. High temperature IHX design requirements are governed in part by the allowable temperature drop between the outlet of NGNP and inlet of the process heat facility. In order to improve the characteristics of heat transfer, liquid metal phase change heat exchangers may be more effective and efficient. This paper explores the overall heat transfer characteristics and pressure drop of the phase change heat exchanger with Na as the heat exchanger coolant. In order to design a very efficient and effective heat exchanger one must optimize the design such that we have a high heat transfer and a lower pressure drop, but there is always a tradeoff between them. Based on NGNP operational parameters, a heat exchanger analysis with the sodium phase change is presented to show that the heat exchanger has the potential for highly effective heat transfer, within a small volume at reasonable cost.

The Effect of Noncondensable Gas on Laminar Film Condensation of Liquid Metals

1973 ◽  
Vol 95 (1) ◽  
pp. 6-11 ◽  
Author(s):  
R. H. Turner ◽  
A. F. Mills ◽  
V. E. Denny
Keyword(s):  
Liquid Metals ◽  
Dominant Role ◽  
Boundary Layer Separation ◽  
Vertical Surface ◽  
Film Condensation ◽  
Vapor Flow ◽  
Interfacial Resistance ◽  
Noncondensable Gas ◽  
Laminar Film ◽  
Laminar Film Condensation

The effect of noncondensable gas on laminar film condensation of a liquid metal on an isothermal vertical surface with forced vapor flow is analyzed. Where necessary the interfacial resistance due to thermodynamic nonequilibrium is included for a condensation coefficient σ = 1. A computer program has been developed to solve a finite-difference analog of the governing partial differential equations and is applied here to the mercury–air and sodium–argon systems. Heat-transfer results are presented for vapor velocities in the range 1 to 100 fps with mass fraction of gas varying from 10−5 to 3 × 10−2. The overall temperature difference ranged from 0.1 to 30 deg F while the temperature levels were 1200 and 900 deg R for mercury–air and 2000 and 1500 deg R for sodium–argon. The effect of noncondensable gas is most marked for low vapor velocities and high gas concentrations. At the lower pressure levels the inter facial resistance plays a dominant role, causing maxima in the curves of q/qNu versus x. For the mercury–air system the adverse buoyancy force causes vapor boundary-layer separation when the free-stream vapor velocity is low.

scholarly journals Condensation Heat Transfer of a Binary Liquid Metal Vapor

1973 ◽  
Vol 16 (102) ◽  
pp. 1928-1937
Author(s):  
Yasuo MORI ◽  
Motokazu UCHIDA ◽  
Toshitsugu HARA ◽  
Tetsuro HARADA
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Metal Vapor ◽  
Condensation Heat Transfer ◽  
Binary Liquid

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.

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