Open-cell Metal Foam Research Articles

Mesostructural Model for the Fatigue Analysis of Open-Cell Metal Foams

Metallic foams exhibit unique properties that make them suitable for diverse engineering applications. Accurate mechanical characterization is essential for assessing their performance under both monotonic and cyclic loading conditions. However, despite the advancements, the understanding of cyclic load responses in metallic foams has been limited. This study aims to propose a mesostructural model to assess the fatigue behavior of open-cell metal foams subjected to cyclic loading conditions. The proposed model considers the previous load history and is based on the analogy of progressive collapse, integrating a finite element model, a fatigue analysis model, an equivalent number of cycles model, and a failure criterion model. Validation against experimental data shows that the proposed model can reliably predict the fatigue life of the metallic foams for specific strain amplitudes.

Fundamental mechanical relations of open-cell metal foam composite materials with reticular porous structure

The compressive behavior is one of the most fundamental mechanical properties for engineering materials. In this paper, the octahedral structure model of porous materials is used to evolve the mechanical analysis model under compressive loading for the porous composite materials, which are resulted from reticular metal foams with pore struts presenting multilayered structure. Starting from this analysis model, some fundamental mechanical relationships, including those of the safe load-bearing and overall strength, have been deduced for these porous composite materials. The compressive strength has been characterized for the porous composite body, corresponding to the overall failure caused by the prior breakage of the strut core and by the prior breakage of the strut shell, respectively. The nickel foam products manufactured on the production line of enterprise were used to make porous composite materials by coating the pore struts with epoxy resin, and the metal foam composite material was obtained with the composite pore-struts of metal/resin multilayered structure. Using this porous composite material for compression experiments, it is found that the experimental data match well with the mathematical relationship from the present theoretical model. The results verify the feasibility of this analysis model and the practicality of the relevant mathematical relationship.

Experimental investigation of the effects of metal foam porous rings on non-Newtonian fluid flow in a double pipe heat exchanger

In this study, we experimentally investigate the effects of metal foam porous rings on heat transfer, pressure drop, and the heat transfer performance ratio of two non-Newtonian fluids in a double-pipe heat exchanger. Enhancing the heat transfer rate is crucial for reducing the size and cost of heat exchangers. We considered various parameters in the experiment, including the power-law index (0.91 and 0.85), porous ring thickness (4, 6, and 8 mm), and the number of porous rings (2, 4, 6). The flow is a turbulent regime, with the Reynolds number ranging from 4000 to 10,000. The test setup includes a test section with a length of 1.6 m and a diameter ratio of 0.6. Open-cell copper metal foam rings with a porosity of 0.92 are placed in the annular pipe, while the internal surface of the inner pipe is subjected to constant heat flux. The results show that, for non-Newtonian Carboxy Methyl Cellulose fluids with concentrations of 0.1% and 0.2%, the average heat transfer coefficients at Reynolds number 4000 increase by 22.0% and 32.0%, respectively. With porous rings, these coefficients increase by 80.3% and 92.7%. Additionally, the average friction factor increases by 19.2% and 35.5% without porous rings and by 320% and 280% with porous rings, respectively. Furthermore, increasing the number of porous rings from 2 to 6 increases the Nusselt number by approximately 16.8% and 17.1%, respectively. The maximum friction factor is 400% higher when using a 0.2% concentration of non-Newtonian fluid. Finally, the performance of the two non-Newtonian fluids improved by approximately 28% and 36.4%, respectively, compared to the base fluid.

Experimental and numerical investigation on fluid flow and heat transfer behaviour of foam cladded pin fin heat sink

As technology advances, there is a growing demand for more efficient cooling solutions in electronics. Open-cell metal foams offer a unique solution, combining the strength of metals with the characteristics of foams, including being lightweight and having a high heat transfer area-to-volume ratio. Fully covering heatsinks with porous materials results in high pressure drop values, which is undesirable for electronics cooling. This study proposes a novel design that incorporates cladded aluminum foams on the pin fins within a heatsink. The hydrothermal performance of the proposed design is experimentally and numerically investigated. The results indicate that increasing the cladding thickness enhances heat transfer performance while increasing the pressure drop. For a heatsink with a pin fin diameter of 5 mm at the Reynolds number of 1121, the foam thickness of 5 mm depicts 46.5 % higher hydrothermal performance compared to a pin fin heatsink without porous while a fully porous covered heatsink depicts 38.9 % higher hydrothermal performance.

Study on the flow and heat transfer characteristics inside high-porosity open-cell copper foams: Experimental and numerical explorations

A metal foam with an open-cell structure is a type of material with low flow resistance, high specific surface area, and strong fluid mixing ability. Open-cell metal foams have broad application prospects in electronic component cooling, multiphase heat exchangers, and compact heat exchangers for aerospace applications. This paper presented experimental and numerical analyses of the flow and heat transfer characteristics of five different copper foams under forced air convection. The pores per inch (PPI) of selected foams were 10, 20, 30, 40, and 60, with porosities ranging from 0.968 to 0.973. Analysis of the collected heat transfer and pressure drop data yielded the overall heat transfer coefficient, unit pressure drop, normalized average wall temperature, inertia coefficient, and resistance coefficient. The influence mechanisms of the porosity and flow velocity on heat transfer were analyzed and discussed. The numerical simulation and experiment fitted well. The results showed that increasing porosity led to a significant increase in heat transfer coefficient and unit pressure drop. The 60 PPI foam brought the maximum pressure drop while achieved the minimum thermal resistance.

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.

Experimental investigation of metal foam embedded surface thermal characteristics using air-jet impingement with different orifice geometry

Experimental investigation of metal foam embedded surface thermal characteristics using air-jet impingement with different orifice geometry

Transport and deposition of nanoparticles in porous media at the pore scale using an Eulerian-Lagrangian method

BackgroundNanoparticle deposition in a subsurface environment decreases the amount of material in the bulk fluid, increases surface roughness, and affects nanofluid flow. Nanoparticle transport in porous media is a complex, multiscale phenomenon. Its macroscopic behavior is determined by phenomena at the pore-scale. Hence, it is necessary and of interest to study the transport and deposition of nanoparticles in porous media using a pore-scale approach. MethodsA computational solver is developed using an Eulerian-Lagrangian approach within the OpenFOAM library. A Berea sandstone and three open-cell metal foams with porosities of 0.8, 0.85, and 0.9, constructed by Laguerre-Voronoi tessellation, were analyzed to study nanoparticle behavior in water. Significant findingsNanoparticle deposition on solid surfaces is influenced by porosity, double layer thickness (NDL), surface potential magnitude (NE1), and nanoparticle diameter. Brownian motion that has a significant impact on nanoparticle transport and deposition is also examined. For nanoparticles with 20 nm diameter, the fraction of particles deposited in foam with 0.8 porosity is about 17 % more than the foam with 0.9 porosity. This difference decreases with nanoparticle diameter. For the particles with 100 nm diameter and more, the effects of Brownian motion on nanoparticle deposition becomes negligible.

Pore-scale study of melting characteristic of phase change material embedded with novel open-celled metal foam

Metallic porous structure is a prevailing heat transfer enhancer for the melting of phase change material (PCM), while the effect of the structure on the enhancement performance is yet to be understood. In this work, a pore-scale numerical study on PCM melting embedded in a truncated cuboctahedron porous structure, referred as TCD metal foam, was performed. The solid–liquid interface, temperature and the variation of liquid fraction were analyzed and compared with those with the tetrakaidecahedron porous structure, referred as TKD metal foam. The effects of natural convection, porosity, pore density and heating temperature are explored. It is found the natural convection shortens the PCM melting time by about 7 % with the considered porosity range and thus cannot be ignored. Results also show that the TCD metal foam better enhances PCM melting near the porous cell corners compared to the TKD metal foam. Further analysis shows the TCD metal foam can better enhance melting at the former stage due to the larger surface area, while the TKD metal foam can better enhance melting at the later stage due to the thicker metallic ligaments. With essentially the same melting time at ɛ = 0.941, the half-melting takes 17.2 % of the complete melting time for TCD metal foam and 20.3 % of the complete melting time for TKD metal foam. A critical porosity value exists when comparing the enhancement performance of these two metal foams, below which the better melting enhancement is shifted from the case with TCD metal foam to the case with TKD one. The critical porosities are 0.941, 0.923 and 0.899 at the pore densities of 10, 20 and 30 PPI respectively.

Wall Heat Transfer Characteristic of Parallel-plate Channel Filled with Open-cell Metal Foams in Large Flow Velocity Range

Abstract High porosity open-cell metal foams can be utilized to fill parallel-plate channels for achieving efficient cooling performance. A wall heat transfer model considering viscous and inertial heat effects is given based on local thermal non-equilibrium theory. Detailed investigations are conducted on influences of parameters on cooling performance. The results indicate that an optimum velocity exists; impacts of porosity and pore size varies with thermophysical properties of fluids and flow velocity; heat transfer resistance also depends on them; increasing foam thickness enhances cooling performance for air under identical velocities but has negligible effect for water; under identical flow rates, decreasing foam thickness improves cooling performance; enlarging base surface area is an effective approach at low flow velocities.

Unlocking the Thermal Efficiency of Irregular Open-Cell Metal Foams: A Computational Exploration of Flow Dynamics and Heat Transfer Phenomena

An open-cell metal foam has excellent characteristics such as low density, high porosity, high specific surface area, high thermal conductivity, and low mass due to its unique internal three-dimensional network structure. It has gradually become a new material for enhanced heat transfer in industrial equipment, new compact heat exchangers, microelectronic device cooling, etc. This research established a comprehensive three-dimensional structural model of open-cell metal foams utilizing Laguerre–Voronoi tessellations and employed computational fluid dynamics to investigate its flow dynamics and coupled heat transfer performance. By exploring the impact of foam microstructure on flow resistance and heat transfer characteristics, the study provided insights into the overall convective heat transfer performance across a range of foam configurations with varying pore densities and porosities. The findings revealed a direct correlation between convective heat transfer coefficient (h) and pressure drop (ΔP) with increasing Reynolds number (Re), accompanied by notable changes in fluid turbulence kinetic energy (e) and temperature (T), ultimately influencing heat transfer efficiency. Furthermore, the analysis demonstrated that alterations in porosity (ε) and pore density significantly affected unit pressure drop (ΔP/L) and convective heat transfer coefficient (h). This study identified an optimal configuration, highlighting a metal foam with a pore density of 20 PPI and a porosity of 95% as exhibiting superior overall convective heat transfer performance.

Methodology for the production of Ni-based open-cell metal foam using ultrasound-assisted electroplating

ABSTRACT Metal foam is a new type of metal that has a variety of uses because its properties can be customised to suit a specific need. Since it has the potential to replace traditional metals, it is important to explore the most advanced methods for creating foams with various levels of porosity. However, it is difficult to produce metal foam cost effectively while also achieving the desired properties due to the random structure and complexity of the process. Therefore, this manuscript outlines a step-by-step guide for creating Ni-based foam using electrodeposition, which overcomes these developmental challenges. Also, the manuscript discusses the characterisation of the foam’s integrity parameters at each stage, as well as the problems encountered during production and their solutions to optimise the developmental process. Finally, the manuscript presents mechanical testing results that demonstrate the foam’s compressive strength of 10.21 MPa at 80% length reduction, porosity of 92% and pressure drop through foam of 0.026% was reported. The developed foam can find usability in corrosive and high-temperature filtration systems, substantiated by mechanical testing results, that are also described.

Melting characteristics of phase change material inside graded aluminum foam based on tetrakaidecahedron model: Pore-scale simulations

Metallic ligaments in open-cell metal foams have effectively improved the heat conduction of phase change materials (PCMs). However, when the gradient direction of porosity is perpendicular to the direction of heat conduction, the mechanism by which graded foam (GF) influences the phase transition of PCM remains elusive. To address this issue, this study employs the pore-scale numerical simulation and develops a numerical model to study the impact of GF on the charging of PCM-foam composites. The analysis identifies the local convection and heat conduction as the most crucial factors influencing heat transfer during phase transition. To effectively examine the role of metallic ligaments in the phase transition, simplified tetrakaidecahedron cells are adopted. The results demonstrate that the GF delays the charging of PCM. Specifically, compared to the homogeneous foam, the full melting time (FMT) of PCM in the GF increases by over 29%. Additionally, the integral-mean temperature response rate (ITRR) of PCM in the GF decreases by 20.2% to 22.1%. Within the GF, the PCM requires more time to melt completely in the tetrakaidecahedron cells with high porosity. Moreover, local convection plays a pivotal role, considerably reducing the FMTs of PCMs by over 85% and increasing the ITRRs of these structures by 588.1% to 599.0%.

INVESTIGATIONS ON OPEN-CELL METAL FOAM–FITTED TUBES FOR HEAT TRANSFER ENHANCEMENT – A DISCUSSION ON ENHANCEMENT MECHANISMS

Metal foams are drawing increasing attention due to their high surface area-to-volume ratio, high thermal conductivity, and low density. Heat exchanger manufacturers are constantly looking for innovative methods toward building highly efficient and compact heat exchangers. To enhance heat transfer, the effective thermal conductivity, fitment of foam on pipe, influence of working fluids, and effect of the bonding method are major areas of investigation. This paper aims to present a review of various investigations conducted on open-cell metal foam for enhancing heat transfer. The pore size distribution of metal foam directly influences the effective thermal conductivity. Recent progress toward bimodal pore size distribution has been reviewed and discussed. There exists a tradeoff between enhancing heat transfer and the corresponding pressure drop. Different configurations of fitting metal foam on pipes, such as fully filled, partially filled, and tubes wrapped with metal foam, are critically reviewed, and their performance is compared. The working fluid and its conditions used with metal foam has tremendous potential toward enhancing heat transfer. The influence of nonrefrigerants, refrigerants, and nanofluids has been presented in this regard. Different bonding methods and their influence on thermal resistance are also reviewed. To date, there is hardly any literature that addresses the performance of metal foam–fitted tubes in condensers and evaporators for vapor compression refrigeration systems. Metal foam-fitted tubes have shown promising results in terms of heat transfer enhancement. The outcome of this review provides insights into further research on the use of metal foam–fitted tubes for refrigeration applications.

Interface characterization of Mg-7Al-1Ca alloy reinforced by integrated 3D[sbnd]Cu open-cell foam

In this study, a 3DCu open-cell metal foam has produced through investment casting, then molten Mg-7Al-1Ca has penetrated through the 3DCu open-cell foam to produce the composite. The composites were heat treated at 290 °C and 480 °C for 1 h to find the adhesion mechanism at the interface of Mg-7Al-1Ca/3D-Cu open-cell foam. Then, the microstructural and mechanical properties of the Mg-7Al-1Ca/3D-Cu open-cell foam interface were investigated by metallography, micro-hardness, and punch-out test. The results indicate that the shear strength of the Mg-7Al-1Ca/3D-Cu interface is a function of the diffusion bond thickness and types of intermetallic phases. The as-cast sample tolerated 98.5 MPa shear stress. However, the 480 °C heat-treated sample has the most fracture toughness compared to the 290 °C heat-treated and the as-cast samples, 84.7, 75.6, and 35.1 J/mm3, respectively. Therefore, the heat-treatment cycle, T = 480 °C, t = 1 h, with decreasing 9.5% (98.5 to 89 MPa) of the shear strength led to an 140% (35.1 to 84.7 J/mm3) increase in energy absorption density of the interface of the composite.

Thermal characteristics of metal foamed flat plate with circular and elliptical impinging jets

ABSTRACT Here, the thermal characteristics of open-cell metal foam (OCMF) integrated stainless steel (SS) foil are investigated experimentally during air jet impingement using circular and elliptical nozzles. The aspect ratio (AR) of the elliptical nozzle is varied from 2 to 4, the Reynolds number (Re) is varied within 5000 - 25,000 and the impinging distance (z/d) is varied within 3–7 during tests. Thin foil thermal imaging infrared thermography has been utilized to record the temperature, and the measured temperature data is used to estimate the performance parameters. The thermal performance is evaluated based on the local, average, and stagnation Nusselt number (Nu) for different configurations. The integration of OCMF with SS foil has been found to significantly enhance heat transfer at the stagnation point in different nozzle configurations. At a Reynolds number (Re) of 5000, the percentage increase in stagnation Nu with foam compared to when there is no foam is found to be 80%, 46%, 38%, and 24% for nozzles with AR of 1, 2, 3, and 4, respectively. The local (0 ≤ x/d ≤2) and average values of Nu for lower impinging distance (z/d ≤5) are found to be higher for the elliptical nozzles, while for z/d ˃ 5, the circular nozzle is found to exhibit better performance. The peak average Nu with nozzle AR = 4 at Re = 25000 is found to be higher than nozzle AR of 3, 2, and 1 by 6.75%, 8.72%, and 23.44%, respectively. Additionally, for the same Re, the peak average Nu of nozzles with AR = 4, AR = 3, and AR = 2 is higher than the circular nozzle by 23.44%, 15.62%, and 13.54%, respectively. New correlations based on experimental results are proposed to determine the local and average Nusselt number as a function of various operating parameters.

Parameter analysis and rapid design of porosity gradient distribution for open-cell metal foam in the latent thermal energy storage unit

The positive gradient porosity design of metal foam is used to improve the thermal performance of the vertical shell-and-tube latent thermal energy storage (LTES) unit. To optimize the gradient design, quantitative analysis is of vital importance. Therefore, the relative offset number EX is proposed in this study, which indicates the porosity difference between upper/down porosity and the mean porosity. Based on the numerical model of a shell-and-tube LTES unit filled with composite phase change material (CPCM) on the shell side, the effects of parameters, including the inlet HTF temperature and velocity, LTES dimensions, porosity, and thermal conductivity of the metal foam on the optimal gradient design are discussed. The optimal EX exhibits little relation with the inlet temperature but increases with the LTES height and thermal conductivity, while decreases with inlet velocity, porosity, and LTES outer radius. With the correlation between the optimal EX and the relative dimensionless number, the effects of these parameters on the optimal EX are integrated and quantified as experience equations so that the optimal porosity gradient of metal foam and the relative reduction melting time can be rapidly obtained under a wide variety of practical applications.

Experimental investigation of the melting performance of a low porosity metal foam/PCM composite heat sink in various configurations

Thermal management is crucial in achieving optimum performance of electronics, reliability, and life. To provide a higher heat dissipation rate over the electronics, metal foam/phase change material (PCM) composites with relatively low porosity have been experimented with in previous efforts. This study aimed to test the thermal performance of metal foam/PCM composite heat sink configurations under a constant heat load. Regular open-cell Al and Al6082-based metallic foams with relatively low-porosity values of 25% to 78%, and pore sizes of 8, 10, and 12 mm were manufactured by the casting method using spherical NaCl space holders. The n-eicosane and the Rubitherm RT-42 were used as PCM. The thermal performance of heat sink configurations was presented through transient temperature history, the solid-liquid interface progress, the safe operating time, and thermal resistance. The results showed that the relatively low-porosity foam configurations with various pore sizes have considerable potential for electronics cooling. The safe operating time of the Al foam/n-eicosane composite heat sink with a porosity of 72% and pore size of 8 mm was obtained as high as 1328 s (22.13 min) with about 380% improvement compared to the heat sink without foam. Al foam and n-eicosane perform better than Al6082 and RT-42, respectively. It is noted that lower thermal resistance and higher safe operating times are achieved for heat sink configurations with higher porosity and smaller pore sizes.

Preparation and tribological properties of different kinds of metal foam-polytetrafluoroethylene co-continuous phase composites

Co-continuous phase composites of polytetrafluoroethylene (PTFE) interpenetrated with five kinds of open-cell metal foams, Cu, Ni, Fe, CuNi and FeNi, were prepared via emulsion impregnation, vacuum impregnation and free sintering. The microstructure, mechanical performance, thermal stability and tribological behavior characteristics of these materials were investigated. The results showed that the filling efficiency of PTFE was between 76.1% and 98.7%. The developed composites generally exhibited enhanced strength and thermal stability. In particular, their wear rate under dry friction conditions was reduced by 63–95% compared with pure PTFE resin, which was ascribed to the effective transfer of friction heat and the enhanced load bearing capacity. However, their tribological performance weakened in a simulated seawater environment because of the diffusion of seawater in the materials and corrosion of the metal skeletons.

Numerical instantiation of complex open-cell metal foam microstructure and evaluation of its thermal performance on the melting of composite phase change material

Numerical instantiation of complex open-cell metal foam microstructure and evaluation of its thermal performance on the melting of composite phase change material