Calculation of the recovery heat flux from film boiling in superfluid helium

Kryukov, A. P.; Sciver, S.W. Van

doi:10.1016/0011-2275(81)90027-8

Cited by 28 publications

(5 citation statements)

References 11 publications

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“…The data obtained in our experiments show that the features of film boiling on a spherical heater can be adequately described by the approaches proposed and developed in [6,7,11].…”

Section: Formula (2) Is Valid Provided Thatmentioning

confidence: 72%

“…The specific heat flux at the interface between the phases is determined by the thermodynamic parameters of the system, the saturation temperature, and the depth to which the heater is immersed into the liquid. A calculation procedure for the recovery thermal load in superfluid helium was proposed in [6]; this load is the minimum heat flux q R in the boiling regime where the direct contact between the heater surface and He-II is established. The specific heat flux at the vapor-liquid (He-II) interface is calculated on the basis of data obtained in studying transfer processes by methods of the molecular kinetic theory.…”

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confidence: 99%

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Experimental study of HE-II boiling on a sphere

Kryukov

Mednikov

2006

J Appl Mech Tech Phys

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Regimes of superfluid-helium boiling on structural-steel spheres 4.8 and 6.0 mm in diameter, with heaters installed inside, are examined. Experimental data on the evolution of vapor films formed on the spherical surfaces are obtained.Introduction. Knowing the features of vapor-film formation and development on heater surfaces is important both for basic research of transfer processes across interfaces and for solving many applied problems. In particular, elucidation of conditions for vapor-phase generation and development in superfluid-helium film boiling is necessary for working out measures providing for reliable cryostatting of superconducting magnets, cables, and other devices, and also for substantiating methods preventing equipment faults.The majority of He-II boiling studies were performed on cylindrical samples and flat heaters [1][2][3][4]. On the other hand, studying the evolution of the vapor film in He-II on spherical surfaces is capable of providing useful information for further development of the theory of heat and mass transfer and for various applications.Experimental Setup. To examine He-II boiling on a sphere, we used an experimental setup that comprised a cryostatting system, an optical system, a video-recording system, and also a system for generating the thermal load and temperature measurement (Fig. 1). The experimental assembly was a glass helium pair consisting of two Dewar flasks of different diameters: An inner flask filled by helium and an outer flask filled by nitrogen. The helium flask (whose inner diameter was 55 mm) was hermetically connected to the pipeline vapor evacuation. The outer flask was open (directly contacting the atmosphere) and was filled by liquid nitrogen serving as a protecting thermal shield. Both flasks had vision slots 20 mm wide, which were used for video recording of the experimental processes. The flasks were aligned so that the slots coincided with each other, which allowed visual observations and video recording of the experimental cell installed in the inner flask. The desired temperature in the helium bath was maintained by vapor evacuation. The liquid temperature was monitored on the basis of the saturation pressure measured with a mercury manometer. The cryostat was filled by liquid helium from an STG-40 liquid-helium transport vessel through an overflow siphon.The processes on the sphere were recorded using an optical system consisting of an MBS-9 microscope placed onto the optical axis of the two Dewar flasks, a video camera coupled with the microscope eyepiece, and a videotape recorder.The experimental sample is schematically shown in Fig. 2. A hole was drilled in a ball bearing to insert a fluoroplastic-insulated carbon heater. Samples 4.8 and 6.0 mm in diameter were used. The heat supplied to the heater was measured by a four-wire circuit. The electric current in the supply circuit was determined from the voltage drop across a reference coil with a nominal resistance of 0.1 Ω. The depth of sphere penetration below the superfluid-helium level was mea...

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“…The data obtained in our experiments show that the features of film boiling on a spherical heater can be adequately described by the approaches proposed and developed in [6,7,11].…”

Section: Formula (2) Is Valid Provided Thatmentioning

confidence: 72%

mentioning

confidence: 99%

Experimental study of HE-II boiling on a sphere

Kryukov

Mednikov

2006

J Appl Mech Tech Phys

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“…10 Experiments were made only for the horizontal cylinder (thin wires) and flat surfaces but not for the ball. However, there is a theoretical relationship for the minimum of heat (reducing) flux at which the vapor film can exist 11 where q is the minimum heat flux.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, a set of initial data allows us to obtain such a solution that can be determined by solving the corresponding stationary problem. 11…”

Section: Discussionmentioning

confidence: 99%

The stability of vapor film immersed in superfluid helium on the surface of the hot ball

Jahangiri

Biglari

2016

Proceedings of the Institution of Mechanical Engineers, Part E:

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In this article, the evolution of vapor film on the surfaces of hot objects immersed in a cryogenic superfluid helium liquid is considered. It is assumed that at the beginning of the process, a thin film of steam exists on the surface of the object that has a spherical shape. If the heat flux is greater than the critical heat flux, the growth of vapor film will continue, otherwise it will collapse. Survey and analysis of the previously mentioned problem has been done using numerical method and the main onjectives are as follows: (a) study the evolution of the vapor film immersed in superfluid helium on the surface of the hot ball and (b) the stability of vapor film immersed in superfluid helium on the surface of the hot ball.

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“…The recovery heat flux is discussed in the following paragraph. The application of the linear kinetic theory [6][7][8][9] leads another heat flux based on the equation of energy balance in non-equilibrium state of two phases…”

Section: (C) and (D)mentioning

confidence: 99%

Visualization study of bubble generation and collapse in He II under microgravity condition

Takada

Kimura

Mamiya

et al. 2014

AIP Conference Proceedings

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Abstract.A visualization experiment to investigate the heat transfer mechanism of He II boiling under microgravity was carried out using the drop-tower which can realize free fall experiments for about 1.3 seconds. The transient behaviors of vapor bubbles around a thin heater wire were optically visualized using a high speed video camera. Time variations of the size of vapor bubble were analyzed. The vapor generation and growth rate were investigated. A vapor bubble collapses slowly when heat current was stopped after generation of a vapor bubble made by a pulsated heat input. In this study, the behavior of bubble shrinking and the growth of vapor column around wire were also compared.

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Calculation of the recovery heat flux from film boiling in superfluid helium

Cited by 28 publications

References 11 publications

Experimental study of HE-II boiling on a sphere

Experimental study of HE-II boiling on a sphere

The stability of vapor film immersed in superfluid helium on the surface of the hot ball

Visualization study of bubble generation and collapse in He II under microgravity condition

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