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ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

HEAT TRANSFER BETWEEN A DISPERSED SYSTEM AND A VERTICAL HEATING OR COOLING SURFACE.

Get access (open in a dialog) DOI: 10.1615/IHTC6.3990
pages 31-36

Résumé

Heat transfer coefficients between a dispersed system and a vertical surface have been determined experimentally. The mechanism of heat transfer was studied to develop an equation for the prediction of these coefficients. In the scope of this article a dispersed system comprises a continuous fluid phase and a dispersed phase consisting of fluid or solid particles. Such systems are bubble or spray columns containing bubbles or drops and fluidized beds with a gaseous or liquid continuous phase. The fluid dynamics of these systems are defined by the density difference Δρ of the two phases, the acceleration gn due to gravity and the viscosity &3951;с of the continuous phase and can be described by the Archimedes number Ar. Furthermore the heat transfer depends on the Prandtl number Prc of the continuous phase. It was found that the maximum heat transfer coefficient αmax can be calculated by the equation
αmax·dpc = Numax =C(Ar·Prc)m The value of the exponent m is 0.333 for bubble or spray columns and liquid fluidized beds. Here the heat transfer coefficient is not influenced by the particle diameter. In the gas fluidized beds, however, the heat transfer decreases with the particle diameter. (m = 0.2)