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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

TRANSIENT SIMULATIONS OF THE HEAT TRANSFER IN THE LIQUID BOUNDARY LAYER AND THE HEATER WALL FOR NUCLEATE POOL BOILING

Get access (open in a dialog) DOI: 10.1615/IHTC13.p28.260
12 pages

Resumo

A newly developed numerical model is used in the present investigation to clarify the relevance of transient heat transfer in the wall and liquid thermal boundary layer and to evaluate the different heat transfer mechanisms in distinct regions during a whole bubble period. The model considers fully transient heat and fluid flow with a free surface of the rising bubble and a periodic calculation of the whole cycle of a growing, detaching and rising bubble including waiting time between two successive bubbles. To ensure that all relevant physical mechanisms are considered, the model is based on a separate multi scale approach with a calculation of microscopic and macroscopic phenomena.
Typical results for heat and mass transfer to a single vapor bubble are shown for all time steps of the bubble cycle. The transient heat flow through different interfaces, e.g. bottom of the heater wall, wall/liquid and liquid/vapor interfaces, is computed for the entire bubble cycle. Thus, it was possible to evaluate the influence of transient heat conduction, heat storage and convection in liquid as well as heat transfer in the wall on the overall heat transfer performance. In particular the influence of the moving micro region, i.e. the thin apparent 3-phase-contact line, on the local temperature gradient within the heater wall could be clarified. In this context the influence of different heat flux boundary conditions and heater wall materials were investigated.