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第13届国际传热学会年报

ISBN 打印: 1-56700-226-9 (CD)
ISBN 在线: 1-56700-225-0

POOL BOILING IN HIGHLY VISCOUS MIXTURES - DESIGN OF A NEW APPARATUS AND RESULTS OF PRETESTS

DOI: 10.1615/IHTC13.p28.590
page 12

R. Span
University of Paderborn, Paderborn, Germany

Mandy Gerber
University of Paderborn, Paderborn, Germany

Irhad Buljina
University of Paderborn, Paderborn, Germany

Elmar Baumhogger
Warme- und Kaltetechnik, Universitat (GH) Paderborn Warburger Str. 100, D-33098 Paderborn, Germany

Abstract

In a project which deals with degassing of polymer solutions using pipe-bundle heat exchangers, noticeable discrepancies have been observed between experimental results for boiling highly viscous mixtures and predictions of available correlations. These differences revealed shortcomings in understanding and modeling of the process. An experimental project is presented, which focuses on fundamentals of heat and mass transfer in boiling highly viscous mixtures. Effects that have been predicted for boiling in such mixtures are discussed.
In order to distinguish between the influence of viscosity and marginal vapor pressure of the highly viscous component, an extremely wide-boiling model system with low viscosity will be investigated. A standard apparatus for measuring heat transfer in an equilibrated pool is modified for measurements on such systems. The design of the modified apparatus is described. Additional modifications necessary to adapt a standard apparatus to wide-boiling highly-viscous mixtures are briefly discussed.
Results are presented for mixtures of n-pentane and poly dimethyl siloxane (silicon oil) with a viscosity of 106 m Pa s boiling in a simple pod-boiling equipment at ambient pressure. Temperature distributions in the pool are reported and nucleation mechanisms are discussed. A new mechanism is observed for bubble formation above the test tube.

IHTC-13 Digital Library

Measurement of fluid temperature with an arrangement of three thermocouples FLOW BOILING OF A HIGHLY VISCOUS POLYMER SOLUTION