Investigation of the Relationship between Morphology and Thermal Conductivity of Powder Metallurgically Prepared Aluminium Foams

Abstract

Among different promising solutions, coupling closed-cell aluminium foam composite panels prepared by a powder metallurgical method with pore walls interconnected by microcracks, with low thermal conductivity phase change materials (PCMs), is one of the effective ways of increasing thermal conductivity for better performance of thermal storage systems in buildings. The internal structure of the foam formation, related to the porosity which decides the heat transfer rate, plays a significant role in the thermal energy storage performance. The dependence of the heat transfer characteristics on the internal foam structure is studied numerically in this work. The foamable precursor of 99.7% pure aluminium powder mixed with 0.15 wt.% of foaming agent, TiH2 powder, was prepared by compacting, and extruded to a volume of 20 × 40 × 5 mm. Two aluminium foam samples of 40 × 40 × 5 mm were examined with apparent densities of 0.7415 g/cm3 and 1.62375 g/cm3. The internal porous structure of the aluminium foam samples was modelled using X-ray tomography slices through image processing techniques for finite element analysis. The obtained numerical results for the heat transfer rate and effective thermal conductivity of the developed surrogate models revealed the influence of porosity, struts, and the presence of pore walls in determining the heat flow in the internal structure of the foam. Additionally, it was found that the pore size and its distribution determine the uniform heat flow rate in the entire foamed structure. The numerical data were then validated against the analytical predictions of thermal conductivity based on various correlations. It has been found that the simplified models of Bruggemann and Russell and the parallel–series model can predict the excellent effective thermal conductivity results of the foam throughout the porosity range. The optimal internal foam structure was studied to explore the possibilities of using aluminium foam for PCM-based thermal storage applications.

Numerical Study on Fluid Flow Behavior and Heat Transfer Performance of Porous Media Manufactured by a Space Holder Method

“…However, in the cold wall part, the smaller the pore size, the higher the temperature at low velocity, and the same temperature at high velocity. It has been proved that the thermal conductivity of metal foam depends insignificantly on pore size [31][32][33], so the temperature difference on the metal foam is mainly caused by the height difference of the model. shows the effect of pore size on the temperature distribution along line 2 for metal fo with different pore sizes.…”

The Effect of Foaming Agents on the Thermal Behavior of Aluminum Precursors

“…In this case, human tissue can grow into the foam cells, resulting in a better connection between the implant and the bone [1,6,7]. A promising functional application of cellular materials is in thermal engineering, where metal foams can find various applications, from thermal energy storage systems to heat sinks [8][9][10].…”

Specifications for Modelling of the Phenomenon of Compression of Closed-Cell Aluminium Foams with Neural Networks

“…Closed-cell aluminium is a well-known engineering material, mostly used where light-weight applications require satisfactory mechanical properties [ 1 , 2 , 3 ] or energy absorption as a determinant [ 2 , 4 ]. Other properties, which make this material multifunctional, are: sound wave attenuation [ 5 , 6 ], electromagnetic wave absorption [ 7 , 8 ], vibration intimidation [ 9 ], thermal conductivity [ 10 , 11 ], relatively easy shape tailoring [ 12 ] and potential for usage in composites [ 13 , 14 , 15 ]. Examples of the usage of aluminium foams include, among others: the automotive industry, space industry, energy and battery field, military applications and machine construction [ 16 , 17 , 18 , 19 , 20 ].…”

“…Taking into consideration so much engineering and design interest in closed-cell aluminium foams, it is a natural consequence that much scientific attention is drawn to the appropriate description of this material in various aspects. A significant number of works focus on structural characterization, e.g., [ 16 , 29 , 30 , 31 ], property analysis, e.g., [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 32 ], manufacturing methods, e.g., [ 12 , 16 , 33 ], experimental investigations, e.g., [ 34 , 35 , 36 , 37 , 38 , 39 ] and modelling. As for modelling, this field is widely researched, and the number of publications about this subject is extensive.…”