年間 8 号発行
ISSN 印刷: 1065-5131
ISSN オンライン: 1563-5074
Indexed in
Enhanced Boiling Heat Transfer in Porous Layers with Application to Electronic Component Cooling
要約
The present contribution deals with a continuous approach to modeling steady state evaporative heat transfer and vapor/liquid counterfiow in porous media, in an attempt o identify the mechanisms responsible for the observed heat transfer enhancement during boiling of liquid coolants in porous layers. A 1-D computer code is developed solving the mass, momentum and energy conservation equations for a bottom and/or volumetrically heated, capillary porous medium. The limitations of such a macroscopic study are recognized and relate mainly to its inability to provide an insight of the micromechanics aspects at the pore level. Nevertheless, the macroscopic calculations are employed to highlight the effects of the relevant parameters (fluid properties, medium permeability and porosity, thermal conductivity of solid matrix, layer thickness) and identify the relative significance of the different mechanisms (capillarity, counter-flow, phase change). A simplified analytical approach is taken to describe the steady state thermohydraulic behaviour of a liquid saturated porous medium. This offers a fast, approximate method for predicting the limiting dryout heat flux in the porous layer. Qualitative agreement is obtained when the theoretical reproduction of the experimental boiling curves is attempted. Based on the understanding gained, investigations are underway to suggest geometric and thermal modifications of the system which may contribute to a significant increase of the heat flux removed in the case of electronic components cooling.
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