Transient heat transfer from a hot nickel sphere moving through water

Walford, F.J.

doi:10.1016/0017-9310(69)90096-9

Cited by 33 publications

(10 citation statements)

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“…Both Walford (1969) an3 Stevens and Witte (1971) noted the formation of a thin pulsating vapour film around the surface of the specimen at all plunge velocities and the latter authors also noted that the heat transfer rate in forced convective boiling was greater than the static pool boiling case which arises after the specimen is suddenly brought to rest. It is important to note that this last conclusion was based on a copper specimen having a diameter of 1.9 cm which could therefore support a thick stable vapour film.…”

Section: T H E Slamming M E T H O Dmentioning

confidence: 97%

“…Experimental measurements and observations by Walford (1969) on the rapid cooling of hot nickel spheres in highly subcooled water concluded that the instantaneous heat flux and cooling rate were independent of the plunge velocity in the range 0.75-1-75 m/s. Similar experiments by Stevens & Witte (1971) using copper spheres plunged into subcooled water reported that the overall heat transfer rate increased with plunge velocity.…”

Section: T H E Slamming M E T H O Dmentioning

confidence: 99%

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The relative merits of various cooling methods

Bald

1985

Journal of Microscopy

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SUMMARY Three different methods of rapidly cooling specimens prior to microscopical analysis are currently in use, namely, slamming, plunging and spraying. The heat transfer processes and specimen cooling rates which are theoretically achievable by each method are discussed and compared with some of the published experimental data. For the slamming method it is concluded that very little improvement in specimen freezing will be achieved by pre‐cooling the block below about 20 K and where pure silver is the most efficient block material. The highest cooling rates and best microscopy by either the plunging or spraying method will be achieved using nitrogen at supercritical pressures. At subcritical pressures propane will produce the best results for metal samples whereas ethane is superior to propane for exposed biological specimens. Future experimental work which relates ice crystal size to cooling rate must be based on the cooling rate at the instant of freezing or nucleation and not on some average cooling rate.

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Section: T H E Slamming M E T H O Dmentioning

confidence: 97%

Section: T H E Slamming M E T H O Dmentioning

confidence: 99%

The relative merits of various cooling methods

Bald

1985

Journal of Microscopy

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“…For the triggering mechanisms and the destabilization of the steam film boiling process, many studies have been done since the 1970s. Among the seven classes of film boiling proposed by Walford [8], the explosive cavity is one possible triggering mode. It can be represented as a sphere (liquid corium) in a spherical cavity (steam film); the sphere is going to progress through the cavity until the sphere nears the steam-liquid interface when another cavity is rapidly formed.…”

Section: Second Phase: Triggering and Fine Local Fuel Fragmentationmentioning

confidence: 99%

Material Effect and Steam Explosion at High Temperature (T > 2300 K)

2005

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In the frame of nuclear power plant safety, the interaction of molten corium (mixture of materials coming from a power plant) with water can generate dynamic loading of the surrounding structures. This phenomenon is called the steam explosion. Many experiments have been performed in the KRO-TOS facility with simulation materials (Al 2 O 3 ) and prototypical materials (U,Zr)O 2 , and different behaviors attributed to a 'material effect' have been observed. Alumina melts produced spontaneous energetic steam explosions, whereas explosions with corium melts (80% UO 2 -20% ZrO 2 ) must be triggered and are less energetic. These differences may be partly attributed to the formation of meta-stable gamma alumina and the ability of liquid alumina to dissolve part of the water, acting like an internal trigger. These results mean that alumina is probably not an adequate simulation of the corium for steam explosion.

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“…This is believed to be caused by the non-uniformity of the forces resisting the motion of a deformable body in a fluid and is sometimes also called the Weber Number effect since a critical Weber number has to be exceeded for hydrodynamic fragmentation to occur. This critical Weber number is believed to be in the region of [15][16][17][18][19][20][21][22]), N WE = P H V £ 2D/a Sm for molten tin drops falling in water.…”

Section: C) Hydrodynamic Fragmentationmentioning

confidence: 99%

Investigation of the fragmentation of molten metals dropped into cold water

Shiralkar¹

1976

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Transient heat transfer from a hot nickel sphere moving through water

Cited by 33 publications

References 0 publications

The relative merits of various cooling methods

The relative merits of various cooling methods

Material Effect and Steam Explosion at High Temperature (T > 2300 K)

Investigation of the fragmentation of molten metals dropped into cold water

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