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Annual Reviews of Heat Transfer

ISSN 1049-0787

Individual price:

$175.00 (Must be sent to your home address)

You can order single issue or individual article. To purchase a single issue or an individual article as well as to view tables of contents and abstracts click on issue number.

Institutional price:

$349.00

Volumes per year:

various

Year 1996

454 pages

Volume price - $141.00

HEAT TRANSFER TO IMMERSED SURFACES IN BUBBLING FLUIDIZED BEDS

John C. Chen
Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015, USA

Kemal Tuzla
Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015, USA

ABSTRACT

Gas fluidized beds are used widely in industry to achieve either physical processing or chemical reactions that require interfacial contact between gas and solid particles. The most prevalent type of fluidized bed is the bubbling bed wherein particles are retained in the bed while the gas passes upward through the interstitial spaces and as rising bubbles. Many of the applications require heat transfer between the fluidized bed medium and immersed surfaces (vessel walls or heat transfer tubes) in order to achieve energy balance. Experimental findings regarding heat transfer to submerged surfaces are summarized, indicating parametric effects of particle size, gas flow rate, operating pressure, thermophysical properties of the particles and gas, bed height, and operating temperature. Although there is no universally accepted theory for the mechanism of heat transfer, there are a number of proposed models. Four basic types of models for the convective heat transfer contribution are reviewed: correlations based on enhanced gaseous convection, analyses of transient heat transfer to packets of particles, analyses of convection by interstitial gas flow through matrix of packed particles, and analysis of thermal transport due to random particle motion by analogy to kinetic theory of gases. Models of radiative contribution are reviewed in two groups: analyses based on equivalent radiant exchange between opaque solid surfaces and analyses based on radiative transport through the participative particle/gas medium.