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LEIDENFROST PHENOMENA

DOI: 10.1615/AtoZ.l.leidenfrost_phenomena

The term Leidenfrost phenomena is given to the body of phenomena observed when a small amount of liquid is placed or spilled on a very hot surface. It is named after the German medical doctor J. G. Leidenfrost [Leidenfrost 1756)].

When spilling liquid on a hot surface, one may note the presence of large and small masses moving rapidly about the surface without wetting it. The process is accompanied by 'dancing' of small droplets, disruption of large masses of liquid by bubbles breaking through, hissing and spitting when liquid contacts a cooler surface, and withal, slowing down of evaporation [Gottfried et al. (1966)].

The Leidenfrost temperature is defined as the plate temperature at which droplet evaporation time is the greatest. For water this temperature is 150°C to 210°C above saturation, depending on the surface and method of depositing the droplet. However, many researchers employ the term Leidenfrost phenomenon to describe the boundary between transition boiling and film boiling of a large liquid mass. The terms rewetting, quenching, sputtering, departure from film boiling, and minimum film boiling, are often synonymously used. (see Boiling.)

Several mechanisms have been proposed to determine the Leidenfrost temperature. The hydrodynamics approach holds that the separation of the liquid-vapor interface from the wall lasts only as long as the vapor generation rate is sufficient to maintain a stable vapor film, e.g., Berenson (1961). The thermodynamic approach assumes that the liquid can never exist beyond a "maximum liquid temperature," which depends on the liquid properties only. Thus, a heated surface whose surface temperature exceeds this limit cannot support liquid contact. The maximum liquid temperature can be determined either from the spinodal line, or from the kinetic theory of bubble nucleation in liquids, e.g., Blander and Katz (1975) and Lienhard and Karimi (1981).

Other explanations relying on system adsorption characteristics have been offered, e.g., Segev and Bankoff (1980) and Olek et al. (1988).

REFERENCES

Berenson, P. J. (1961) Film boiling heat transfer from a horizontal surface. Trans. ASME. J. Heat Transfer. 83: 351−358.

Blander, M. and Kate, J. L. (1975) Bubble nucleation in liquids. AlChE. J. Vol. 21: 833−848.

Gottfried, B. S., Lee, C. J., and Bell K. J. (1966) The Leidenfrost phenomenon: film boiling of liquid droplets on a flat plate. Int. J, Heat Mass Transfer, Vol. 9: 1167−1187. DOI: 10.1016/0017-9310(66)90112-8

Leidenfrost, J. G. (1756) De aquae communis nonnullis qualitatibus tractatus (A tract about some qualities of common water). Duisburg on Rhine-An original copy of this Treatise is in the Yale University Library.

Lienhard, J. H. and Karimi, A. (1981) Homogeneous nucleation and the spinodal line. Trans. ASME. J. Heat Transfer. Vol. 103: 61−64.

Olek, S., Zvirin, Y., and Elias, E. (1988) The relation between the rewetting temperature and the liquid-solid contact angle. Int. J. Heat Mass Transfer. Vol. 31: 898−902. DOI: 10.1016/0017-9310(88)90147-0

Segev, A. and Bankoff, G. (1980) The role of adsorption in determining the minimum film boiling temperature. Int. J. Heat Mass Transfer. Vol. 23: 623−637. DOI: 10.1016/0017-9310(80)90007-1

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