Metal Foam Research Articles

Experimental and numerical assessment of thermal characteristics of PCM in a U-shaped heat exchanger using porous metal foam and NanoPowder

The utilization of Latent Heat Thermal Energy Storage (LHTES) has gained significant attention to address the disparity between energy supply and demand. One of the key advantages lies in the use of phase change materials (PCM). The purpose of this research is to overcome this obstacle by focusing on enhancing the thermal efficiency of an advanced thermal energy storage system specifically designed for solar domestic and industrial application. to overcome this obstacle by focusing on enhancing the thermal efficiency of an advanced thermal energy storage system specifically designed for solar domestic and industrial application. Through computational and experimental studies, a novel and small LHTES system with parallel U-shaped heat exchanger (USHX) has been created and investigated. To improve performance, two approaches are employed: optimizing thermal efficiency by dispersing nano-sized graphite powders into the paraffin material, and/or incorporating metal foams. The PCM is RT35HC, and the hot/cold heat transfer fluid is H2O, which travels via the U-shaped tube. The model incorporates the enthalpy-porosity technique to account for phase change phenomena. After comparing the numerical outcomes with the experiments herein run, data are shown in terms of liquid fraction, temperature evolution, stored energy, and a dimensionless parameter that characterizes the phase change process. The findings suggest that the proposed methods for enhancing heat transfer can enhance the thermal efficiency of systems. The outcomes illustrate that by addition of all methods, reduces the melting time by 13.39 %, 60.77 %, and 71.93 %, when compared to system with pure PCM.

Waste heat recovery from exhaust gases using porous metal fins: a three-dimensional numerical study

Abstract The objective of this study is to investigate the impact of different porous metal samples on the hydro-thermal characteristics of a single cylinder with porous fins using computational fluid dynamics. Commercially used porous samples with pore densities of 10, 20, and 40 PPI were used in this study for heat recovery from exhaust flue gas. The three-dimensional computational domain with porous aluminium fins attached to a tube over which high-temperature exhaust gas flows in a crossflow arrangement mimics a waste heat recovery system. Computations were performed at Reynolds number of 6000-9000, using the realisable κ-ϵ turbulence model. Three fin diameter to tube diameter ratios (Df/D = 2, 2.5, and 3) were considered. The local thermal non-equilibrium model is implemented for energy transfer, as it is more accurate for a high-temperature gradient scenario in a waste heat recovery system. The foam sample with the highest pore density was observed to have the highest pressure drop due to low permeability. A maximum heat transfer and Nusselt number were achieved for a 40 PPI foam sample due to a reduced flow rate inside the porous zone. The overall performance of metal foam samples at varying fin diameters was evaluated based on the area goodness factor (j/f) and a heat transfer coefficient ratio to pumping power per unit heat transfer surface (Z/E). Analysis of these two parameters suggests using 20 PPI foam at Df/D = 2.

Integrated Thermal Management System Concept With Combined Jet Plate, High Porosity Aluminum Foam, and Target Plate for Enhanced Heat Transfer

Abstract An experimental investigation was carried out on high porosity metal foams subjected to array jet impingement with an objective to develop enhanced heat transfer configurations. In this study, we propose an integrated thermal management system (TMS) aimed toward leveraging the conjugate heat transfer capabilities of target plate, metal foam, and the jet plate—all made from aluminum and assembled such that a proper contact between them can be established. Steady-state heat transfer experiments were carried out for 10 and 20 pores per inch (PPI) aluminum foams of 0.93 porosity. Both metal foams were 12.7-mm thick. The normalized jet-to-jet spacing was varied from 2 to 12 times the jet diameter, while the jet diameter was fixed. The ratio of the jet plate thickness and jet diameter (nozzle aspect ratio) was 6.35, which ensured proper development of jets inside the nozzles. Experiments were conducted over a wide range of Reynolds number (based on jet diameter) varied from 100 to 5000. The obtained convective heat transfer coefficient for different configuration was evaluated in context with pressure drop. The analysis of experimental results reveal that large open area ratio jets combined with high porosity metal foams provide highly efficient and high-performance cooling for the investigated range of Reynolds numbers.

Using metal foam and nanoparticle additives with different fin shapes for PCM-based thermal storage in flat plate solar collectors

This research focuses on employing heat transfer enhancement techniques as well as nanoparticles, porous metal foams, and extended surfaces, for the PCM-based thermal energy storage system of a flat plate solar collector. Numerical investigations are carried out for different combinations of the aforementioned techniques, with I-, Y-, and T-shaped fins as the extended surface. The mathematical model is developed with porous media equations, where nanoparticles are embedded in the PCM under the assumption of an equivalent single-phase medium. Results suggest that employing these techniques one by one augments heat transfer performances in terms of reduced melting time. The addition of both metal foam and nanoparticles in the straight wall (case A) reduces melting time by 85.16% when compared to the pure-PCM case, while a 84.38% reduction is reached if only foams are employed. The I-shaped fins (case B) are shown to have an impact too; they provide a 37.07% melting time reduction with only PCM, reaching 89.68% and 86.19% with nanoparticles with foams, respectively. This means that metal foams have a primary role in reducing melting time, where nanoparticles and I-shaped fins become helpful too. Furthermore, by considering all techniques together, the heat storage rate increases by an order of magnitude.

Vibration and buckling analysis of porous metal foam thin-walled beams with closed section

This paper investigates the vibration and buckling analysis of porous metal foam thin-walled box beams. These beams exhibit a unique structural configuration with symmetrical and asymmetrical porosity distributions along their wall thickness, thereby altering the effective mechanical properties. The first-order shear deformable beam theory is employed and the governing equations are derived using the Hamilton’s principle. Numerical results are presented for porous metal foam thin-walled box beams under simply-supported, clamped–clamped and clamped-free boundary conditions. The effects of various porosity parameters, length-to-side and side-to-wall-thickness ratios on the beams’ performance are also examined. A comprehensive comparison between the porous metal foam thin-walled box beams and their counterparts in the form of equivalent homogeneous are presented.

Nonlinear transient response of rotating graphene platelets reinforced metal foams blades with initial geometric imperfection

In this paper, a new mechanical model including initial geometric imperfection is developed to investigate the nonlinear transient response of graphene platelets reinforced metal foams (GPLRMF) blades subjected to blast load. Combined with higher-order shear deformation plate theory (HSDT) and von-Karman geometric nonlinearity, the nonlinear motion equations are established, in which the Coriolis force, centrifugal force as well as initial geometric imperfection are simulated. Considering cantilever boundary condition, the partial differential equations are transformed into a series of ordinary differential equations by Galerkin discretization. Using the four order Runge-Kutta algorithm, the nonlinear transient response is numerically researched, and the time histories and phase trajectories are obtained. In addition, the effectiveness of the current research is validated by comparing the results with the existing valuable literatures. The influences of rotating speed, presetting angle, initial geometric imperfection, material property, damping coefficient, and blast load parameter on the dynamic deflection and instantaneous speed are presented. Numerical results reveal that the nonlinear transient dynamics of the composite blades under blast load are significantly influenced by initial geometric imperfection.

Numerical Simulation of Natural Convection in a Rhombic Enclosure with Heated Sidewall Coated with Metal Foam

Numerical Simulation of Natural Convection in a Rhombic Enclosure with Heated Sidewall Coated with Metal Foam

Performance improvement of novel latent thermal energy storage system with two-layer metal foam porosities

A 2D numerical analysis was conducted to examine the melting performance of a shell-and-tube-type phase change material with a two-layer copper foam having higher and lower porosity levels. The design parameters for these two layers of metal foam consisted of three different volume fill ratios (VFR) (30 %/70 %, 50 %/50 %, and 70 %/30 %) and three different shapes (circular, semi-circular, and elliptical) for the lower porosity layer. The results showed that a semicircular-shaped low porosity layer with a 30 % VFR had the least melting time of 475 s. When the VFR increased to 50 %, the elliptical and circular shapes had the least melting time of 394 s. However, at a VFR of 70 %, only the elliptical shape had the least melting time of 323 s. Furthermore, the results were compared with the uniform porosity metal foam system, and deduced that the two-layer system did not always have the lower melting time compared with that of the uniform porosity system because it depended on the VFR and shape of the different porosities filled in the different layers. Additionally, for an average porosity of the metal foam, an optimal combination of two different porosities was observed for the melting performance.

Numerical investigate on the heat transfer performance and mechanical analysis of a water sublimator

Water sublimators play a critical role in efficiently managing the high thermal load of spacecraft in a vacuum environment, ensuring their proper functioning. This article focuses on a novel cold plate water sublimator driven by a porous sublimation tube structure, which is still in the theoretical research stage. Numerical methods are employed to study the evaporation, freezing, and sublimation processes, with validation against experimental data. The average absolute error of the four operating conditions is 1.33 K, and the ice layer thickness error is 8.33 %. Additionally, a method to calculate the effective thermal conductivity of porous aluminum foam is proposed, with a model error of 9 %. The sublimator's heat transfer characteristics are significantly influenced by the porosity of the aluminum foam and sublimation tubes. The impacts on temperature behavior, ice thickness, feed water pressure, and stress are carefully examined. Results reveal aluminum foam porosity of 0.7 and sublimation tube porosity of 0.3. Moreover, the study explores how different heat loads affect the sublimator's operation mode. Heat loads above 2 W/cm2 cause evaporation and dryness within the sublimation tube, while excessively small heat loads lead to ice formation and increased stress on the aluminum foam structure. These findings provide valuable insights for water sublimator design.

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

The velocity field and temperature field are crucial for metal foams to be used as a heat exchanger, but they are difficult to obtain through physical experiments. In this work, the fluid flow behavior and heat transfer performance in open-cell metal foam were numerically studied. Porous 3D models with different porosities (55-75%) and pore sizes (250 μm, 550 μm, and 1000 μm) were created based on the porous structure manufactured by the Lost Carbonate Sintering method. A wide flow velocity range from 0.0001 m/s to 0.3 m/s, covering both laminar and turbulent flow regimes, is fully studied for the first time. Pressure drop, heat transfer coefficient, permeability, form drag coefficient, temperature and velocity distributions were calculated. The calculated results agree well with our previous experimental results, indicating that the model works well. The results showed that pressure drop increased with decreasing porosity and increasing pore size. Permeability increased and the form drag coefficient decreased with increasing porosity, and both increased with increasing pore size. The heat transfer coefficient increased with increasing velocity and porosity, whereas it slightly decreased with increasing pore size. The results also showed that at high velocity, only the metal foam close to the heat source contributes to heat dissipation.

Computational Modelling of Heat Transfer through Aluminium Metal Foams for LiFePO4 Battery Cooling

Abstract: Temperature is crucial for battery pack durability and power. Folded fin and serpentine channel cooling methods are mostly used to cool the pack. However, fluid absorption during cooling can reduce capacity and cause downstream temperatures to be higher than upstream. Consistent cooling is vital to prevent temperature variation and increase battery pack lifespan. This work is concerned with the computational study of heat dissipation from open-cell aluminium metal foam for cooling LiFePO4 battery packs. The battery module consists of six pieces of pouch cell and three pieces of the aluminium foam heat sink. In the present study, aluminium foams are positioned between the LiFePO4 battery modules that are arranged in a vertical manner. Thermal interaction between the battery module and aluminum foam was studied. The effect of pore density on heat dissipation performance at different mass flow rates was explored. It has been discovered that aluminium foam with suitable porosity and pore density can efficiently cool the LiFePO4 battery pack. This paper provides a theoretical framework for designing a thermal management system for lithium- ion batteries using aluminium foam. Background: Metal foam cooling is an established technique for thermal management of Lithiumion batteries in electric vehicles. Objective:: The present study aims to analyze heat transfer through aluminium metal foams for vertically aligned LiFePO4 battery pack cooling. Methods: The Darcy extended Forchheimer (DEF) model examines fluid flow through metallic foams, using the local thermal non-equilibrium model to determine heat transfer. Results: The impact of the density of pores in the aluminium foam on the average wall temperature and temperature difference along the battery surface is determined. The variation of heat transfer of lithium-ion battery modules for different mass flow rates is also studied. Conclusion: The results indicate that utilizing aluminium foam as a heat transfer medium for battery modules significantly enhances their thermal management performance.

Waste heat management in electric motors using thermoelectric generator integrated with phase change material and metal foam-embedded heat sink

The waste heat management process from various thermal sources is associated with promising results in the energy conversion field. Thermoelectric generators integrated with phase change materials containing metal foams are useful means for recovering waste heat and converting it into electrical energy. Installing these hybrid cases on common heat sources and providing a practical strategy for waste heat management addresses a significant research gap in this field. The aim of this study is to manage waste heat from a three-phase asynchronous electric motor of a milling machine for the first time using a novel prototype thermoelectric system. Four thermoelectric modules (connected electrically in series) with zero-cooling energy phase change material and copper foam heat sink were embedded on the motor body. Hence, continuous and fluctuating loads were imposed on the motor, starting from ambient temperature. This caused the motor body to heat up and transfer the wasted heat to the module and the environment. The results of this study show that the proposed system was successfully started via the waste heat of the motor body. Thermal energy was absorbed from the hot side of the module, and the hybrid heat sink controlled the temperature of the cold side. Moreover, an appropriate temperature difference was provided across the module, and the system produced electricity for a long time during milling operation. The maximum output voltage in constant and periodic loads, with on/off durations of 180 s and 360 s, was recorded as 960 mV, 1280 mV, and 1440 mV, respectively. The mentioned hybrid thermoelectric system provides a unique solution for waste heat management in industrial applications, improving economic savings.

Fundamental Aspects of Wire Arc Additive Manufacturing for Aluminum Foams

Fundamental Aspects of Wire Arc Additive Manufacturing for Aluminum Foams

Optimizing the photocatalytic properties of macroporous geopolymer foam: Influence of SILAR-technique synthesis conditions

Macroporous cross-linked materials such as 3D honeycomb foams are used as substrates for heterogeneous photocatalysis. They offer a number of interesting properties. They are highly open-porosity substrates, guaranteeing optimum mass and radiation transfer, making them ideal for photo-conversion applications such as photo-oxidation or photo-reduction, which take place in photo-reactors for pollutant degradation or solar fuel production. Many cross-linked supports such as polymeric and metallic foams studied in the literature have revealed photocatalytic capacities similar to those obtained for the catalyst nanoparticle suspensions used as a reference. To reduce the production costs of this type of material, geopolymers, widely used in civil engineering, offer a wide range of properties suitable for shaping cellular foams. In addition to their low cost and mechanical properties, it is also possible to impart porous properties and modulate their characteristics according to the synthesis operating conditions so as to elaborate macroporous cellular foams. In this study, we propose to investigate the photocatalytic properties of honeycomb geopolymer foams coated with a catalyst: ZnO. To achieve ZnO deposition, the SILAR technique was applied by modifying the key synthesis operating conditions, i.e. precursor concentration and the number of quenching cycles applied. The results obtained make it possible to define the optimum operating conditions (pH, temperature) and, above all, the number of cycles and precursor concentration required to obtain the best photocatalytic efficiency. These innovative and promising materials, little studied in the literature, are prime candidates for solar photo-conversion applications.

Reinforcement effect of fly ash with different morphologies on aluminum foam prepared via powder metallurgy

Powder metallurgy has outstanding advantages in the preparation of aluminum foam fillers and special-shaped aluminum foams, which can realize near-net-shape forming. To improve the mechanical properties of aluminum foams prepared by powder metallurgy, low-cost solid waste fly ash (FA) was selected as the reinforcement phase, and the strengthening effect of the FA particles with different morphologies on the mechanical properties of the aluminum foam was analyzed. The results show that the strengthening effect of 1.0 wt% mullite whiskers prepared from the original FA on aluminum foam is superior to that of spherical raw FA or irregular granular FA. In particular, a reinforced aluminum foam with a yield strength of 20.76 MPa was obtained after precursor foaming at 610 °C for 10 min because the wettability between the whiskers and matrix is improved when the whiskers were coated with Sn in advance and the foamable precursor was obtained via hot-pressing.

Microstructural characterization of bimodal composite metal foams under compression with machine learning

Cellular materials are gaining popularity in today’s major sectors. The aim is to develop high-performance materials to meet customer and application demands. This study revolves around the beginning of the failure; computed tomography and statistical image analysis assisted with machine learning were employed to quantitatively characterize the occurring processes within the structure at the beginning of the well-known plateau effect. Simple techniques (e.g., easily obtainable shape parameters, forest decision, 2D image slices) were employed to sort the structural elements into seven classes based on their visual appearances. The presented method can provide additional information about the fracture mode of the different foams, possibly applying/extending them for other types of closed-cell (composite or not) foams.

Supramolecular metallic foams with ultrahigh specific strength and sustainable recyclability

Porous materials with ultrahigh specific strength are highly desirable for aerospace, automotive and construction applications. However, because of the harsh processing of metal foams and intrinsic low strength of polymer foams, both are difficult to meet the demand for scalable development of structural foams. Herein, we present a supramolecular metallic foam (SMF) enabled by core-shell nanostructured liquid metals connected with high-density metal-ligand coordination and hydrogen bonding interactions, which maintain fluid to avoid stress concentration during foam processing at subzero temperatures. The resulted SMFs exhibit ultrahigh specific strength of 489.68 kN m kg−1 (about 5 times and 56 times higher than aluminum foams and polyurethane foams) and specific modulus of 281.23 kN m kg−1 to withstand the repeated loading of a car, overturning the previous understanding of the difficulty to achieve ultrahigh mechanical properties in traditional polymeric or organic foams. More importantly, end-of-life SMFs can be reprocessed into value-added products (e.g., fibers and films) by facile water reprocessing due to the high-density interfacial supramolecular bonding. We envisage this work will not only pave the way for porous structural materials design but also show the sustainable solution to plastic environmental risks.

Effect of Compaction Pressure on Microstructural, Mechanical, and Thermal Properties of Aluminum Foams Processed through Space-Holder Technique

Effect of Compaction Pressure on Microstructural, Mechanical, and Thermal Properties of Aluminum Foams Processed through Space-Holder Technique

Thermal Emissivity and Heat Capacity of Composite Metal Foam

Composite metal foam (CMF) is a new class of material based on a mixture of metal matrix composites and metal foams. While the mechanical properties of CMF are well studied, its thermal properties, particularly at extreme temperatures, are yet to be evaluated and established. This study investigates the specific heat capacity of stainless-steel composite metal foam at temperatures up to 1200 °C while comparing data obtained using the laser flash method and a differential scanning calorimetry method (DSC). Moreover, it outlines a detailed procedure for investigating the surface emissivity of composite metal foam (CMF) as a function of the emissivity of separate components (spheres and matrix). It uses experimental and analytical procedures to show how emissivity is directly affected by surface roughness, temperature, sphere curvature and viewing angles. The CMF used in this study consists of 316L stainless steel matrix and stainless-steel hollow spheres with varying sphere sizes.

Optimal design on fin-metal foam hybrid structure for melting and solidification phase change storage: An experimental and numerical study

A fin-metal foam composite structure is employed in the phase change energy storage coupled Organic Rankine Cycle system to enhance thermal performance. The 3-D numerical model is validated through an experimental system to analyze the impact of metal foam parameters and fluctuating heat source parameters (amplitude and half-period) on the system's storage-release process during heat source fluctuation. According to the Taguchi method, metal foam porosity significantly influences the total storage-release time. An increase in porosity leads to a continuous increase in the total storage-release time, while an increase in PPI and a decrease in heat source amplitude initially increase and then decrease the total storage-release time. Under constant metal foam PPI (10) and porosity (0.97), Case T (half period = 60 and amplitude = 1.0) demonstrates a 2.04 % increase in average heat transfer rate and a 1.78 % reduction in total storage-release time compared to Case 0 (constant heat source). The average heat release rate sees a 4.23 % increase, while total heat storage and heat release rise by 0.96 % and 1.87 %. The research has specific technical significance for the photothermal application of phase change energy storage technology to the variability and unpredictability of solar energy.