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Experimental investigation of the effects of foam height, emissivity and orientation on buoyancy-driven convection in open-cell aluminium foam

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Abstract
In this paper air-saturated buoyancy-driven convection in open-cell aluminium foam is studied. The effects of foam height, radiative heat transfer and orientation are experimentally investigated. Two aluminium foam heat sinks with the same baseplate dimensions (6” by 4”) are tested. Their respective foam height is 22 mm and 40 mm. The aluminium foam has a porosity of 0.946 and a pore density of 10 pores per linear inch. The heat sinks are tested in a vertical and a horizontal orientation. The effect of radiation is studied by comparing untreated heat sinks with painted versions. During the experiments the power dissipated by the heat sinks is measured as function of the temperature difference between the baseplate of the heat sink and the ambient. The temperature difference is varied from 10 to 70°C. By increasing the height of the foam, the heat dissipated by the heat sink increases by 49% at a temperature difference of 10°C. However, due to the high hydraulic resistance of the foam, only part of the extra heat exchanging surface area contributes to the convective heat transfer. This is illustrated qualitatively using smoke visualisations. Painting the heat sinks results in an increase in heat transfer by 10% and 17% on average for the high and low heat sink respectively due to the higher emissivity values. The lower relative improvement of the high heat sink can be explained by the larger temperature drop along the height of the heat sink due to the low thermal conductivity. Finally, the low painted heat sink dissipated up to 18% more heat in its horizontal orientation compared to the vertical one.
Keywords
natural convection, Metal Foam

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Chicago
Billiet, Marijn, Sven De Schampheleire, Henk Huisseune, Zhu Hua Qiu, and Michel De Paepe. 2015. “Experimental Investigation of the Effects of Foam Height, Emissivity and Orientation on Buoyancy-driven Convection in Open-cell Aluminium Foam.” In 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings, ed. Josua Meyer, 833–838.
APA
Billiet, M., De Schampheleire, S., Huisseune, H., Qiu, Z. H., & De Paepe, M. (2015). Experimental investigation of the effects of foam height, emissivity and orientation on buoyancy-driven convection in open-cell aluminium foam. In Josua Meyer (Ed.), 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings (pp. 833–838). Presented at the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT).
Vancouver
1.
Billiet M, De Schampheleire S, Huisseune H, Qiu ZH, De Paepe M. Experimental investigation of the effects of foam height, emissivity and orientation on buoyancy-driven convection in open-cell aluminium foam. In: Meyer J, editor. 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings. 2015. p. 833–8.
MLA
Billiet, Marijn, Sven De Schampheleire, Henk Huisseune, et al. “Experimental Investigation of the Effects of Foam Height, Emissivity and Orientation on Buoyancy-driven Convection in Open-cell Aluminium Foam.” 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings. Ed. Josua Meyer. 2015. 833–838. Print.
@inproceedings{6885348,
  abstract     = {In this paper air-saturated buoyancy-driven convection in open-cell aluminium foam is studied. The effects of foam height, radiative heat transfer and orientation are experimentally investigated. Two aluminium foam heat sinks with the same baseplate dimensions (6{\textquotedblright} by 4{\textquotedblright}) are tested. Their respective foam height is 22 mm and 40 mm. The aluminium foam has a porosity of 0.946 and a pore density of 10 pores per linear inch. The heat sinks are tested in a vertical and a horizontal orientation. The effect of radiation is studied by comparing untreated heat sinks with painted versions. During the experiments the power dissipated by the heat sinks is measured as function of the temperature difference between the baseplate of the heat sink and the ambient. The temperature difference is varied from 10 to 70{\textdegree}C.
By increasing the height of the foam, the heat dissipated by the heat sink increases by 49\% at a temperature difference of 10{\textdegree}C. However, due to the high hydraulic resistance of the foam, only part of the extra heat exchanging surface area contributes to the convective heat transfer. This is illustrated qualitatively using smoke visualisations.
Painting the heat sinks results in an increase in heat transfer by 10\% and 17\% on average for the high and low heat sink respectively due to the higher emissivity values. The lower relative improvement of the high heat sink can be explained by the larger temperature drop along the height of the heat sink due to the low thermal conductivity.
Finally, the low painted heat sink dissipated up to 18\% more heat in its horizontal orientation compared to the vertical one.},
  author       = {Billiet, Marijn and De Schampheleire, Sven and Huisseune, Henk and Qiu, Zhu Hua and De Paepe, Michel},
  booktitle    = {11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Proceedings},
  editor       = {Meyer, Josua},
  isbn         = {9781775921080},
  language     = {eng},
  location     = {Kruger National Park, South Africa},
  pages        = {833--838},
  title        = {Experimental investigation of the effects of foam height, emissivity and orientation on buoyancy-driven convection in open-cell aluminium foam},
  year         = {2015},
}