N. Dukhan , H. Klatzke , M. Liang , M. Ghannam , D. Ramaswamy
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引用次数: 0
Abstract
Metal foams have been investigated for both forced and free convection heat transfer applications. However, there appear to be no engineering models for determining the thermal resistance of metal foams when used in free convection. In this paper, a new engineering model is presented to fill this gap. The model is developed from first principles of heat transfer and the concept of thermal resistance network. It identifies the various resistances present inside the foam, and the associated temperature difference for each resistance. A few coefficients were needed to calibrate the model, and they were determined from experimental data on an actual aluminum foam sample having 20 pores per inch (ppi) and a porosity of 76.4 %. The dimensions of the foam sample were 109 mm by 110 mm by 20 mm. The sample was subjected to three heat fluxes: 884.1 W/m2, 1217.7 W/m2 and 1884.9 W/m2, and was cooled by room air. Subsequently, the model of the thermal resistance of the foam was validated by further experiments on three foam samples having different materials and morphological properties. These samples included aluminum and copper foam, and had porosities in the range 74.5 %–78.0 %. There was very good agreement between the thermal resistances of the foam as predicted by the model and their experimental counterparts. The heated wall temperature was predicted by the model within reasonable error. The model allows optimization of metal foam in terms of pore density and porosity for free convection. The model also shows that no advantage is gained by using copper foam as opposed to aluminum foam for passive cooling.
期刊介绍:
The International Journal of Thermal Sciences is a journal devoted to the publication of fundamental studies on the physics of transfer processes in general, with an emphasis on thermal aspects and also applied research on various processes, energy systems and the environment. Articles are published in English and French, and are subject to peer review.
The fundamental subjects considered within the scope of the journal are:
* Heat and relevant mass transfer at all scales (nano, micro and macro) and in all types of material (heterogeneous, composites, biological,...) and fluid flow
* Forced, natural or mixed convection in reactive or non-reactive media
* Single or multi–phase fluid flow with or without phase change
* Near–and far–field radiative heat transfer
* Combined modes of heat transfer in complex systems (for example, plasmas, biological, geological,...)
* Multiscale modelling
The applied research topics include:
* Heat exchangers, heat pipes, cooling processes
* Transport phenomena taking place in industrial processes (chemical, food and agricultural, metallurgical, space and aeronautical, automobile industries)
* Nano–and micro–technology for energy, space, biosystems and devices
* Heat transport analysis in advanced systems
* Impact of energy–related processes on environment, and emerging energy systems
The study of thermophysical properties of materials and fluids, thermal measurement techniques, inverse methods, and the developments of experimental methods are within the scope of the International Journal of Thermal Sciences which also covers the modelling, and numerical methods applied to thermal transfer.