Search Results (694)

Pre-coated metal sheets (PCM), as a popular product in modern coating industries, offer significant advantages such as simple processing, lightweight properties, and excellent manufacturability. The pretreatment layer within its coating system has a significant impact on overall corrosion resistance. In this study, through a comparative analysis of two chromate-free pretreatment systems, we conducted a thorough investigation into the combination of the pretreatment layer and examined the impact on the corrosion performance of pre-coated metal sheets. It was found that the phytic acid-based pretreatment layer enhances the adhesion between the primer and the substrate by forming strong chemical bonds with the primer layer, which effectively inhibits the lateral diffusion of corrosive media to the metal surface. Consequently, pre-coated metal sheets with the phytic acid-based pretreatment exhibit superior anti-foaming performance compared to the system using the silane-based pretreatment layer. This provides a new insight into the design and development of Cr-free pretreatment systems with better corrosion resistance performance. Full article

This study examines the thermal performance of phase change material (PCM)–metal foam composites under base heating, a configuration more relevant to compact thermal energy storage (TES) and electronics-cooling applications, compared to the widely studied side-heated case. Metal foams with pore densities of 10, 20, and 40 PPI, but identical porosity (volumetric value), were impregnated with two PCMs (paraffin RT55 and RT64HC) and tested under varying heat fluxes. The thermophysical properties of three PCMs (RT42, RT55, and RT64HC) were first characterized using the T-history method. A control case consisting of pure PCM revealed significant thermal lag between the heater and the PCM, whereas the inclusion of a metal foam improved temperature uniformity and accelerated melting. The results showed that PPI variation had little influence on melting completion time, while PCM type, viz., melting temperature, strongly affected duration. Heat flux was the dominant parameter: higher input power substantially reduced melting times, although diminishing returns were observed at elevated heat fluxes. An empirical correlation from the literature, originally developed for side-heated foams, was applied to the base-heated configuration and reproduced the main melting trends, though it consistently underpredicted completion times at high fluxes. Overall, embedding PCMs in metal foams enhances heat transfer, mitigates localized overheating, and enables more compact and efficient TES systems. Future work should focus on developing correlations for non-adiabatic cases, exploring advanced foam architecture, and scaling the approach for practical energy storage and cooling applications. Full article

In this paper, spherical-shaped catalytic materials with needle-like stacking structures were synthesized in situ on the foam nickel substrate using the hydrothermal method, resulting in the NiM (M = Co, Mn, W, Zn)-MOF series. Furthermore, the catalyst with the best performance was obtained by adjusting the ratio of metal elements. Electrochemical tests show that NiCo-MOF (Ni: Co = 1:2) has the best electrocatalytic performance. During the UOR process, NiCo-MOF exhibits the optimal performance in 1 M KOH and 0.5 M urea solution, with a potential of only 1.33 V at a current density of 10 mA/cm². The improvement in the activity of NiCo-MOF can be attributed to the synergistic effect between the Ni and Co bimetals, which leads to an increase in the electron transfer rate, the exposure of active sites, and an improvement in conductivity. Moreover, metal–organic framework materials are widely used as electrocatalysts due to their compositional diversity, rich pore structures, and high specific surface areas. Meanwhile, NiCo-MOF was used as a UOR and HER catalyst to assist the overall water decomposition with urea, and it showed relatively excellent performance. Only a voltage of 1.56 V was required to drive the current density of 10 mA/cm² of the UOR || HER system. Therefore, the synthesized NiCo-MOF catalyst plays an important role in improving the efficiency of hydrogen production from water electrolysis and has promising sustainable application prospects. Full article

The development of high-efficiency and stable oxygen evolution reaction (OER) electrocatalysts is crucial for sustainable hydrogen production via water splitting. Single-atom catalysts (SACs) represent a promising direction, yet their performance heavily relies on the support material. Herein, we report a highly active OER catalyst comprising ruthenium (Ru) species supported on Fe-doped nickel carbonate hydroxide (NFCH) grown on nickel foam (NF). The NFCH support, synthesized via a hydrothermal method, possesses a high specific surface area and excellent electrical conductivity. The incorporation of carbonate anions (CO₃²⁻) enhances structural stability and interfacial hydrophilicity. Ru was subsequently decorated onto NFCH via electrodeposition to form the NFCH-Ru_x series (where x denotes the mmol amount of Ru precursor). The optimized NFCH-Ru₃ catalyst exhibits outstanding OER performance in 1 M KOH, requiring a low overpotential of only 220 mV to achieve a current density of 10 mA cm⁻², with a small Tafel slope of 40.92 mV dec⁻¹. Furthermore, it demonstrates remarkable durability with negligible activity loss (2.9%) after 12 h of continuous operation, outperforming many recently reported non-precious metal-based catalysts. This work highlights the potential of metal carbonate hydroxides as superior supports for developing high-performance OER electrocatalysts. Full article

An ambit of enhancing heat transfer throughout thermal convection in a cavity is explored numerically in this study, contemplating the heat dispersal from a segmental heat source circumscribed in a square-vented porous cavity with a moving lid. The cavity can be used as a heat sink for electronic cooling, material processing, and convective drying. Aluminum $10$ PPI metal foam saturated by aluminum oxide–water nanofluid is occupied in this lid-driven vented cavity system. The bottom cavity wall is fully and partially heated by a heat source of specific length $L_H$, and the left wall and inlet fluid are kept at the same cold temperature, while the right wall and top-driven wall are thermally insulated. Thermal dispersion and local thermal non-equilibrium effects are included in an energy equation, and continuity and Darcy–Brinkmann–Forchheimer momentum equations are implemented and resolved by utilizing the finite volume method with the aid of a vorticity–stream function approach operation. The inspirations behind pertinent parameters, including the Reynolds number ($Re=10–50$), Grashof number ($Gr={10}^3–{10}^6$), inlet and outlet ports’ aspect ratio ($D/H=0.1–0.4$), outlet port location ratio ($S/H=0.25–0.75$), and discrete partial heating ratio ($L_H/L=0.25–1$) are scrutinized. The baseline circumstance corresponds to full-length heating $L_H/L=1$ and the outlet port location ratio $S/H=0.25$. The results reveal that the fluid and heat flow domains are addressed mostly via these specification alterations. For $Gr={10}^3$, increasing $Re$ from $10$ to $40$ does not alter streamlines or the isotherm field, but when $Re=50$ it is detected that streamlines increase monotonically. Streamlines are not altered when $L_H/L$ and $S/H$ are amplified but strengthened more when the opening vent aspect ratio is increased. A greater temperature difference occurs as $L_H/L$ is raised from $0.25–0.75$ and isotherms are intensified, and the thermal boundary layer becomes more distinct when $S/H$ is augmented. The average Nusselt number rises as $Re$, $Gr$, $L_H/L$, and $D/H$ are increased by about $30\%$, $3.5\%$, $23\%$, and $19.4\%$, respectively, and it decreases with $S/H$ amplifying is increased by around $5.5\%$. Full article

Ensuring thermal stability is a major concern in lithium-ion battery systems. Although phase change materials (PCMs) provide a passive approach for temperature regulation, they are limited by poor heat conduction and potential leakage during phase transitions. This study develops a novel composite PCM (CPCM) using paraffin (PA) as the matrix, copper foam (CF) as a conductive skeleton (10–30 pores per inch, PPI), and a low-melting-point alloy (LMA) as an encapsulant to prevent leakage. The effects of CF pore size on thermal conductivity, impregnation ratio, and leakage resistance were systematically investigated. Results show that CPCM with 10 PPI CF achieved the highest thermal conductivity (4.42 W·m⁻¹·K⁻¹), while LMA encapsulation effectively eliminated leakage. The thermal management performance was evaluated on both a single 18,650 LIB cell and a 2S2P module during rate discharging at 1C, 2C, and 3C. For the module at 3C, the 10 PPI CPCM significantly lowered the maximum temperature from 75.9 °C to 44.6 °C and critically reduced the maximum temperature difference between cells from 10.2 °C to a safe level of 1.2 °C, significantly improving temperature uniformity. This work provides a high-conductivity and leakage-proof CPCM solution based on LMA-encapsulated CF/PA for enhanced thermal safety and uniformity in LIB modules. Full article

This paper presents three simple and efficient advanced optimization algorithms, namely the best–worst–random (BWR), best–mean–random (BMR), and best–mean–worst–random (BMWR) algorithms designed to address unconstrained and constrained single- and multi-objective optimization tasks of the metal casting processes. The effectiveness of the algorithms is demonstrated through real case studies, including (i) optimization of a lost foam casting process for producing a fifth wheel coupling shell from EN-GJS-400-18 ductile iron, (ii) optimization of process parameters of die casting of A360 Al-alloy, (iii) optimization of wear rate in AA7178 alloy reinforced with nano-SiC particles fabricated via the stir-casting process, (iv) two-objectives optimization of a low-pressure casting process using a sand mold for producing A356 engine block, and (v) four-objectives optimization of a squeeze casting process for LM20 material. Results demonstrate that the proposed algorithms consistently achieve faster convergence, superior solution quality, and reduced function evaluations compared to simulation software (ProCAST, CAE, and FEA) and established metaheuristics (ABC, Rao-1, PSO, NSGA-II, and GA). For single-objective problems, BWR, BMR, and BMWR yield nearly identical solutions, whereas in multi-objective tasks, their behaviors diverge, offering well-distributed Pareto fronts and improved convergence. These findings establish BWR, BMR, and BMWR as efficient and robust optimizers, positioning them as promising decision support tools for industrial metal casting. Full article

This review covers the current state, challenges, and future directions of catalytic combustion technologies for mitigating fugitive methane emissions from the fossil fuel industry. Methane, a potent greenhouse gas, is released from diverse sources, including natural gas production, oil operations, coal mining, and natural gas engines. The paper details the primary emission sources, and addresses the technical difficulties associated with dilute and variable methane streams such as ventilation air methane (VAM) from underground coal mines and low-concentration leaks from oil and gas infrastructure. Catalytic combustion is a useful abatement solution due to its ability to destruct methane in lean and challenging conditions at lower temperatures than conventional combustion, thereby minimizing secondary pollutant formation such as NO_X. The review surveys the key catalyst classes, including precious metals, transition metal oxides, hexa-aluminates, and perovskites, and underscores the crucial role of reactor internals, comparing packed beds, monoliths, and open-cell foams in terms of activity, mass transfer, and pressure drop. The paper discusses advanced reactor designs, including flow-reversal and other recuperative systems, modelling approaches, and the promise of advanced manufacturing for next-generation catalytic devices. The review highlights the research needs for catalyst durability, reactor integration, and real-world deployment to enable reliable methane abatement. Full article

Mattresses represent one of the most widespread and problematic bulky waste streams worldwide, due to their unavoidable daily use, their high presence in municipal solid waste flows, and the complexity of their end-of-life management. Their heterogeneous composition—combining polyurethane foams, textiles, metal springs, and adhesives—makes separation and recovery difficult, leading many discarded mattresses to end up in landfills or incinerators, with associated greenhouse gas emissions and the loss of valuable secondary resources. Within this context, recycling emerges as a priority alternative under the circular economy framework, enabling material recovery and reducing reliance on traditional disposal methods. Among current options, mechanical recycling is especially promising, as it provides energy savings and lower emissions compared to thermal treatments. However, its large-scale implementation requires improvements in product design, collection logistics, and regulatory frameworks to address existing challenges. This article provides a critical review of the current state of mattress recycling and valorization, examining technological advances, environmental impacts, and systemic barriers. It also highlights successful initiatives in the hospitality and healthcare sectors, which illustrate the potential of circular strategies to transform bulky waste management and promote sustainable material flows. Full article

Thermal energy storage (TES) is a crucial technology for mitigating energy supply–demand mismatches and facilitating the integration of renewable energy. This study proposes a novel horizontal phase change TES unit integrated with partially filled metal foam (MF) and fins, divided into six sub-regions (ε₁–ε₆) with graded pore parameters. A comprehensive numerical model is developed to investigate the synergistic heat exchange mechanism and energy storage performance. The results demonstrate that porosity in Porosity-1 (ε₁) and Porosity-2 (ε₂) regions dominates melting dynamics. Through multi-objective optimization, targeting both minimal energy storage time and maximal energy storage rate, an optimal configuration (Case TD) is derived after technical design. Case TD features porosity values ε₁ = ε₂ = ε₃ = ε₅ = ε₆ = 0.97 and ε₄ = 0.98, where the graded porosity distribution balances heat conduction efficiency and energy storage capacity. Compared to the uniform MF case (Case 1) and the fin-only case (Case 6), Case TD reduces TES time by 51.75% and 17.39%, respectively, while increasing the mean TES rate by 102.55% and 19.12%, respectively. This design minimizes the TES capacity loss (only decreasing by 2.14% compared to Case 1) while maximizing the energy storage density and improving the efficiency–cost trade-off of the phase-change material-based system. It provides a scalable solution for rapid-response TES applications in solar thermal power plants and industrial waste heat recovery. Full article

This work presents a non-destructive methodology to estimate the residual porosity and mechanical properties of titanium foams produced via Hot Isostatic Pressing (HIP) followed by solid-state foaming (SSF). Pulsed laser-spot thermography was employed to measure thermal diffusivity in compact and foamed Ti6Al4V-ELI samples derived from powders of different granulometries. A power-law correlation between thermal diffusivity and porosity was used to estimate post-foaming porosity, which was then used to predict elastic modulus, yield strength, and ultimate tensile strength. Results highlight the potential of thermal diffusivity as a reliable indicator of structural performance, offering a rapid and fully non-destructive route for evaluating metallic foams in biomedical and aerospace applications. Full article

Methane steam reforming is the most widely adopted hydrogen production technology. To address the challenges associated with the large radial thermal resistance and low mass transfer rates inherent in the tubular packed bed reactors during the MSR process, this study proposes a structural design optimization that integrates annular metal foam gas channels along the inner wall of the reforming tubes. Utilizing multi-physics simulation methods and taking the conventional tubular reactor as a baseline, a comparative analysis was performed on physical parameters that characterize flow behavior, heat transfer, and reaction in the reforming process. The integration of the annular channels induces a radially non-uniform distribution of flow resistance in the tubes. Since the metal foam exhibits lower resistance, the fluid preferentially flows through the annular channels, leading to a diversion effect that enhances both convective heat transfer and mass transfer. The diversion effect redirects the central flow toward the near-wall region, where the higher reactant concentration promotes the reaction. Additionally, the higher thermal conductivity of the metal foam strengthens radial heat transfer, further accelerating the reaction. The effects of operating parameters on performance were also investigated. While a higher inlet velocity tends to hinder the reaction, in tubes integrated with annular channels, it enhances the diversion effect and convective heat transfer. This offsets the adverse impact, maintaining high methane conversion with lower pressure drop and thermal resistance than the conventional tubular reactor does. Full article

Practical applications such as solar power energy systems, electronic cooling, and the convective drying of vented enclosures require continuous developments to enhance fluid and heat flow. Numerous studies have investigated the enhancement of heat transfer in L-formed vented cavities by inserting heat-generating components, filling the cavity with nanofluids, providing an inner rotating cylinder and a phase-change packed system, etc. Contemporary work has examined the thermal performance of L-shaped porous vented enclosures, which can be augmented by using metal foam, using nanofluids as a saturated fluid, and increasing the wall surface area by corrugating the cavity’s heating wall. These features are not discussed in published articles, and their exploration can be considered a novelty point in this work. In this study, a vented cavity was occupied by a copper metal foam with $PPI=10$ and saturated with a copper–water nanofluid. The cavity walls were well insulated except for the left wall, which was kept at a hot isothermal temperature and was either non-corrugated or corrugated with rectangular waves. The Darcy–Brinkman–Forchheimer model and local thermal non-equilibrium models were adopted in momentum and energy-governing equations and solved numerically by utilizing commercial software. The influences of various effective parameters, including the Reynolds number ($20\le Re\le 1000$), the nanoparticle volume fraction ($0\%\le \phi \le 20\%$), the inflow and outflow vent aspect ratios ($0.1\le D/H\le 0.4$), the rectangular wave corrugation number ($N=5$ and $N=10$), and the corrugation dimension ratio ($CR=1$ and $CR=0.5$) were determined. The results indicate that the flow field and heat transfer were affected mainly by variations in $Re$, $D/H$, and $\phi$ for a non-corrugated left wall; they were additionally influenced by $N$ and $CR$ when the wall was corrugated. The fluid- and solid-phase temperatures of the metal foam increased with an increase in $Re$ and $D/H$. The fluid-phase Nusselt number near the hot left sidewall increased with an increase in $\phi$ by $\left(25–60\right)\%$, while the solid-phase Nusselt number decreased by $\left(10–30\right)\%$, and these numbers rose by around $3.5$ times when the Reynolds number increased from $20$ to $1000$. For the corrugated hot wall, the Nusselt numbers of the two metal foam phases increased with an increase in $Re$ and decreased with an increase in $D/H$, $CR$, or $N$ by $10\%$, $19\%$, and $37\%$. The original aspect of this study is its use of a thermal, non-equilibrium, nanofluid-saturated metal foam in a corrugated L-shaped vented cavity. We aimed to investigate the thermal performance of this system in order to reinforce the viability of applying this material in thermal engineering systems. Full article

Printed circuit heat exchangers (PCHE) are ideal for use in very demanding operating conditions. In addition, they are characterized by very high efficiency, which can still be increased. This paper presents new concepts for improving PCHE heat exchangers. The aim of the described work was to evaluate the potential for improving the performance of printed circuit heat exchangers by incorporating open-cell metal foam as the heat exchanger packing material. The evaluation was conducted based on the results of numerical simulation of supercritical carbon dioxide cooling flowing through printed circuit heat exchanger channels filled with 40 PPI copper foam with 90% porosity. A unit periodic region of the heat exchanger comprising two adjacent straight channels for cold and hot fluid was analyzed. The channels had a semicircular cross-section and a length of 200 mm. Studies were conducted for three different channel diameters—2, 3, and 4 mm. The range of mass flux variations for cold fluid (water) and hot fluid (sCO₂) were 300–1500 kg/(m²·s) and 200–800 kg/(m²·s), respectively. It was found that in channels filled with metal foam, carbon dioxide cooling is characterized by a higher heat transfer coefficient than in channels without metal foam. In channels of the same diameter, heat flux was 33–63% higher in favor of the channel with metal foam. Thermal effectiveness of the heat exchanger with metal foam can be up to 20% higher than in the case of a heat exchanger without foam. Despite very high pressure drop through channels filled with metal foam, thermal–hydraulic performance can also be higher—even 4.7 in the case of a 2 mm channel. However, both these parameters depend on flow conditions and channel diameter, and under certain conditions may be lower than in a heat exchanger without metal foam. The results of the presented work indicate a new direction for the development of PCHE heat exchangers and confirm that the use of metal foams in the construction of PCHE heat exchangers can contribute to increasing the efficiency and effectiveness of the processes in which they are used. Full article

Waste glass recycling generates waste streams such as fine glass fraction, waste ceramics containing fine glass, and waste polyethylene plastics. All of the aforementioned streams contain contaminants of organic and inorganic origin that are difficult to remove. This research was conducted to determine technological processes aimed at achieving a circular economy (CE) in the recycling of waste glass. Foam glass was made from the fine-grained, multicolored fraction of contaminated glass, an effective method for recycling glass waste at a low cost. A frothing system based on manganese oxide (MnO₂) and silicon carbide (SiC) was proposed, and an optimum weight ratio of MnO₂/SiC equal to 1.0 was determined. The possibility of controlling the process to achieve the desired foam glass densities was demonstrated. Statistical analysis was used to determine the effect of the MnO₂/SiC ratio and MnO₂ content on the density of the resulting foam glass products. Waste ceramics contaminated with different-colored glass were transformed into ceramic–glass granules. The characteristic temperature curve of the technological process was determined. The metal content in water extracts from ceramic–glass granules and pH value indicate their potential use for alkalizing areas degraded by industry and agriculture. Waste polyethylene-based plastics were converted into polyethylene waxes by thermal treatment carried out in two temperature ranges: low temperature (155–175 °C) and high temperature (optimum in 395 °C). The melting temperature range of the obtained waxes (95–105 °C) and their FTIR spectral characteristics indicate the potential application of these materials in the plastics and rubber industries. The integrated management of all material streams generated in the glass recycling process allowed for the development of a CE model for the glass recycling plant. Full article