Jaroslav Jerz; Arun Gopinathan; Jaroslav Kováčik
Abstract
The structure of aluminium foam is highly porous consisting of aluminium (or its alloy) filling up the space among gas pores. Although pores formed during foaming of aluminium melt are closed, there are always microscopic cracks in the walls of solid foam, so that the porosity is predominantly ...
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The structure of aluminium foam is highly porous consisting of aluminium (or its alloy) filling up the space among gas pores. Although pores formed during foaming of aluminium melt are closed, there are always microscopic cracks in the walls of solid foam, so that the porosity is predominantly open. This preference of aluminium foam allows to fill pores with a Phase Change Materials (PCMs) capable repeatedly to store and release a huge amount of latent heat of phase transition from solid to liquid state and vice versa. The excellent thermal conductivity of the aluminium, forming the pore walls, predetermines aluminium foam castings for the production of highly efficient heat exchangers in various industrial sectors, especially in the building industry. The most promising technique for the production of near-net-shaped structural components containing a dense aluminium surface skin and porous inner foamed aluminium structure is powder metallurgical route. Lightweight self-supporting interior ceiling panels impregnated by PCM presented in this contribution, utilize their high mechanical stiffness and their ability to store large amounts of latent heat at a constant temperature. The application of foamed aluminium appears to be very promising also for heat exchangers covering the entire pitched roof of the building which provides not only the better recovery of the heat from the building surroundings but also the dissipation of unwanted excess heat from the interior when needed.
Jaroslav Jerz; František Simančík; Peter Tobolka
Abstract
The energy efficiency of buildings is today mostly improved by upgrading the energy performance of the building envelope and facilities. However, huge energy reductions can also be achieved by a focus on the novel systems enabling to cover natural energy fall-outs resulting from generation much excess ...
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The energy efficiency of buildings is today mostly improved by upgrading the energy performance of the building envelope and facilities. However, huge energy reductions can also be achieved by a focus on the novel systems enabling to cover natural energy fall-outs resulting from generation much excess heat during the peak time (summer, day) which is currently almost not possible to use during periods of excessive energy consumption (winter, night). This main drawback of the solar energy can be very efficiently solved by storing and later evolving of accumulated heat from solar gains according to the day-night as well as the seasonal, i.e. summer-winter cycle. A novel solution described in this contribution is an opportunity to reduce significantly the energy demands for heating/cooling and heating of Domestic Hot Water (DHW). The costs for construction and operation of future buildings are considerable reduced if the heat comfort is maintained by aluminium foam heating/cooling ceiling heat exchangers that allow storage of the heat in the form of latent heat of phase transition of Phase Change Materials (PCMs) impregnated in the porous structure of aluminium foam for later use or, for removal of undesirable heat to the building surroundings during comparatively colder summer nights.
Dipen Kumar Rajak; L. A. Kumaraswamidhas; S. Das
Abstract
Aluminium foam is an isotropic porous metal of cellular structure in the order of 75-80 vol. % of the pores. In turn the novel mechanical, physical and chemical composition, properties depends on the density of foam, i.e. lies in between 0.4-2.4 g/cm 3 . Aluminium foam filled structures are used in collide, ...
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Aluminium foam is an isotropic porous metal of cellular structure in the order of 75-80 vol. % of the pores. In turn the novel mechanical, physical and chemical composition, properties depends on the density of foam, i.e. lies in between 0.4-2.4 g/cm 3 . Aluminium foam filled structures are used in collide, energy absorption, sound absorbing and vibration damping applications. In this article the compressive deformation behaviour of rectangular, square and round aluminium foam (LM 25 + 10wt% SiCp) filled and empty mild steel samples respectively are analyzed to identify the more energy absorption rate per unit volume in diverse strain rate by means of the compressive testing at room temperature. The experiments were performed on a universal testing machine the results showed that the round cross-section had more energy absorption than the rectangular and square cross section respectively. Also the amount of energy absorption will be greater with low foam density for round section tubes. We have seen that an increasing interest in using aluminium foams as inside the thin-wall mild steel tubes for maximum specific energy absorption rate. This work shows the admirable capability of aluminium alloy foam in applications in which it is essential to absorb compression energy.
Dipen Kumar Rajak; L.A. Kumaraswamidhas; S. Das
Abstract
In this study compression behavior and energy absorption capacity of aluminium foam-filled square tubes under the divers strain rate in between 0.01 to 1/s at room temperature were studied. The foam-filled thin-wall square tube were made up of aluminium tube, aluminium tube as its shell and closed–cell ...
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In this study compression behavior and energy absorption capacity of aluminium foam-filled square tubes under the divers strain rate in between 0.01 to 1/s at room temperature were studied. The foam-filled thin-wall square tube were made up of aluminium tube, aluminium tube as its shell and closed–cell LM 30 + 15% SiCp Al-alloy foam as its core. The result shows that the plateau region of the stress-strain graph exhibited marked fluctuant serration which is clearly related formation of the folds. The axial deformation mode of foam-filled square tube were the same as the empty sample tube, but the fold number of foam-filled sample tube were more than that of empty sample tubes. The axial compression load and specific energy absorption rate of foam-filled sample tubes were higher compared to the sum of the empty sample tubes and aluminium foam due to the contact between tube & foam-filled. When compare with empty aluminium tube samples to foam filled samples, energy absorption increases considerably. This work indicates the excellent ability of Al-alloy foam in application in which it is necessary to absorb compressed energy.
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