Search Results (173)

This study introduces a novel class of architected foam structures based on triply periodic minimal surface (TPMS) geometries for passive battery thermal management. Unlike conventional cold plates that rely on active pumping or high-conductivity solid materials, the proposed TPMS-like foams leverage convective fluid transport within a lightweight, electrically insulating polymer matrix. We present the design, fabrication, and experimental characterization of Schwarz Primitive TPMS structures manufactured via injection molding using silicone rubber, which has a comparable quality to additively manufactured polymer cold plates but with significantly lower manufacturing complexity and cost. The TPMS cold plates achieve passive fluid circulation without external pumps, reducing parasitic power consumption while maintaining thermal resistance values of approximately 23.5 K/W. Although its thermal resistance is higher than that of an aluminum plate of the same size (2.7 K/W), the TPMS cold plate is electrically insulating and offers additional safety benefits. Additionally, it can be fabricated from and filled with fire-retardant materials to prevent thermal propagation while maintaining a relatively low temperature gradient. Mechanical compression testing of TPMS foam samples with about 30% solid volume fraction showed a compressive strength of 86.2 kPa at 0.2 strain, equivalent to 30.5% of the compressive modulus of solid silicone (282.6 kPa). Compared to solid silicone plates (thermal resistance is 1420 K/W), the TPMS fluid-filled structures reduce thermal resistance by more than two orders of magnitude. This work establishes design rules, fabrication protocols, and performance benchmarks for TPMS-based passive cooling devices, offering a scalable pathway toward safer, lighter, and more energy-dense battery packs. Full article

Coastal power plants draw seawater from the open ocean through their cooling-water circulation systems. The cooling water falls over an overflow weir inside the siphon well, entraining large quantities of air, and generates a foam pollution plume upon discharge to the sea. By combining physical model experiments with numerical simulation, this study investigates the key factors governing foam stability and the aeration behavior of the water downstream of the siphon-well overflow weir. The principal conclusions are as follows: among the three single-factor variables tested in controlled laboratory conditions—temperature, salinity, and shellfish-flesh suspension concentration—the biological substance proxy showed the strongest effect on foam stability; when the shellfish-flesh suspension concentration reaches 20% (mass/volume basis, independently prepared), the foam volume and half-life increase by factors of 1.4 and 3.36, respectively, relative to the 4% baseline condition. When the dimensionless aeration depth z/z₉₀ < 0.75, the air-concentration profile rises relatively slowly with depth, whereas it increases more rapidly as the free surface is approached. Within the investigated viscosity range of 1.0–8.3 mPa·s (1.0 mPa·s for the pure-water control and 1.5–8.3 mPa·s for the measured viscosities of the 4–20% shellfish-flesh suspensions), the cross-sectional mean air concentration shows an overall decreasing trend as the liquid-phase viscosity increases, and the total bubble number density decreases correspondingly. The findings provide a laboratory-based indication of the mechanisms that must be addressed in the development of physical foam-suppression technologies; confirmation against field discharge water is required. Full article

Lithium-ion battery fires are governed by continuous heat release during thermal runaway, flammable gas venting, and thermal coupling between adjacent cells. Even after visible flames are extinguished, post-extinguishment temperature rise, thermal runaway propagation, and reignition may still occur. This review establishes a full-process control framework linking flame suppression, sustained cooling, thermal runaway propagation mitigation, and reignition control. Within this framework, water-based agents, clean gaseous agents, dry powder agents, foams, cryogenic media, and hybrid suppression methods are not only compared by their flame extinguishment performance but also by their cooling capability, thermal runaway propagation/reignition control, scenario applicability, and environmental impacts. Evaluation metrics and standardization requirements are further integrated to support cross-study comparison and practical suppressant selection. Existing studies indicate that a single suppressant is generally unable to achieve both rapid flame extinguishment and post-extinguishment thermal stability. Multi-mechanism synergy, realistic scenario validation, and standardized evaluation protocols are therefore essential for improving the full-process control of lithium-ion battery fires. Full article

This work presents a new Battery Thermal Management System (BTMS) concept utilizing a metal foam manifold cold plate (MFMCP), developed specifically to meet the rising thermal dissipation needs of lithium-ion batteries. By coupling a manifold flow design and high-conductivity metal foams (characterized via SEM), the system significantly enhanced heat transfer and temperature uniformity. A Local Thermal Equilibrium (LTE) model evaluated thermal–hydraulic performance across varying Reynolds numbers (40–200), foam structures (PPI and porosity), and Al₂O₃ nanofluid concentrations. Results indicated that an optimal foam structure (95 PPI, porosity of 0.905) yielded a significant surface temperature reduction of 15 K. Although the Al₂O₃ nanofluid provided an additional cooling effect of 0.3 K, its pressure penalty lowered the performance evaluation criterion (PEC); the highest initial PEC of 2.57 was established when employing the pure base fluid without any functional additives. A Multi-Layer Perceptron (MLP) model was developed to expedite design validation, achieving high predictive accuracy as evidenced by an R² of 0.983 and an MRE of 1.8%. Subsequent optimization via a genetic algorithm (GA) further increased the maximum PEC by 12% to 2.88. Equal pumping power system simulations indicated that the MFMCP design achieved a peak cell temperature of 304.35 K, outperforming traditional designs which peaked at 308.33 K. Furthermore, transient tests at 1C to 2C discharge rates confirmed consistent cooling improvements, demonstrating the MFMCP’s promising potential for dynamic operational conditions. Full article

Background/Objectives: Natural calcium carbonate materials such as Rügen chalk have a long history of use in balneology and rehabilitation, particularly for musculoskeletal disorders, yet their application remains largely confined to traditional, labour-intensive forms such as powders, suspensions, and packs, which limit usability and broader clinical translation. This study aimed to develop an alginate-based solid foam incorporating Rügen chalk and to evaluate how key formulation components influence its structural, mechanical, and thermal properties relevant for therapeutic use. Methods: Alginate–chalk foams were prepared by mechanical mixing of a sodium alginate–Rügen chalk paste with an amino acid-based surfactant, while in situ CO₂ generation from D–glucono–δ–lactone (GDL) induced calcium-mediated alginate gelation and foam stabilization. A central composite design with response surface methodology was used to assess the effects of alginate, chalk, and Perlastan^®–GDL content on foam pH, overrun, firmness, springiness, pore volume, sphericity, pore density, specific internal surface area, and heat-loss time. Foam microstructure was characterized by optical microscopy and microcomputed tomography (µCT), and the thermal conductivity and cooling behaviour of the selected formulation were compared with therapeutic peat. Results: Stable, elastic solid foams with a three-dimensional porous architecture were obtained across the investigated composition range. Foam overrun (30.8–57.1%) was primarily governed by sodium alginate and Rügen chalk concentrations, while firmness (7.4–15.2 N) increased predominantly with alginate content, and springiness remained high (70–78%), indicating good elastic recovery. Response surface modelling and ANOVA confirmed sodium alginate as the dominant factor influencing both mechanical and structural properties, with statistically significant effects on overrun, firmness, springiness, heat loss, porosity, and specific internal surface. µCT analysis revealed that all foam formulations were predominantly composed of fine, closed-cell pores, with over 96% of pores having volumes below 0.5 mm³ and a consistent median pore volume of 0.02 mm³. Structural differences between formulations were governed primarily by pore number and spatial distribution rather than pore size. Strong correlations were identified between µCT-derived parameters, particularly between specific internal surface, porosity, and pore density, confirming that internal architecture is controlled by pore population rather than individual pore dimensions. Thermal analysis demonstrated that the optimized formulation exhibited thermal conductivity comparable to therapeutic peat and maintained clinically relevant temperatures (35–45 °C) for more than one hour. Based on predefined performance criteria (overrun ≥ 50%, firmness ≤ 10 N, heat loss ≥ 120 s), formulation 7 was identified as optimal, combining favourable mechanical properties, structural uniformity and thermal retention. Conclusions: Alginate-based solid foams incorporating Rügen chalk constitute a feasible and tunable platform that combines efficient mineral loading, elastic porosity, and effective heat retention, offering a practical and modern alternative to conventional mineral-based therapeutic applications in balneology and rehabilitation. Full article

Rising demand for high-performance battery thermal management systems (BTMSs) has rendered single-mode cooling insufficient for advanced lithium-ion batteries (LIBs) in new energy vehicles (NEVs), particularly under high discharge rates. This study proposes a synergistic hybrid BTMS integrating composite phase-change material (CPCM)–aluminum foam with liquid cooling to enhance thermal regulation of cylindrical battery modules under 5 C discharge conditions. Multiple liquid-cooled plate (LCP) configurations, including serpentine, straight, and leaf-shaped designs, together with different flow channel topologies (FCTs), were systematically investigated and optimized. The effects of coolant flow speed (CFS) and ambient temperature were also analyzed. Results indicate that the optimized leaf-shaped LCP with FCT #2 delivers superior performance, limiting the maximum temperature to 309.98 K, reducing temperature difference by 7.6%, and decreasing pressure drop by 88.79% compared to the serpentine configuration. Increasing CFS improves heat dissipation and delays PCM melting, although it raises pressure losses. Furthermore, the proposed system maintains a cell-to-cell temperature difference below 0.51 K, indicating excellent thermal uniformity. Compared to a CPCM-only system, the hybrid BTMS reduces peak temperature by 8.81 K under elevated ambient conditions (309.15 K), demonstrating strong potential for reliable and efficient thermal management in demanding operating environments. Full article

Thermal regulation of lithium-ion (Li-ion) battery modules is a critical constraint for electric vehicle (EV) safety and durability, particularly during high-C-rate operation. Phase change materials (PCMs) have emerged as promising passive solutions due to their latent heat storage capability; however, current literature is heavily biased toward organic paraffin-based systems and lacks structured benchmarking across PCM categories and integration architectures. This review provides a systematic comparative assessment of PCM-based battery thermal management systems (BTMSs) comprising organic, inorganic, and eutectic materials under EV-relevant discharge conditions. The review is structured according to the conventional classification of PCMs; however, the available literature is predominantly focused on organic materials, particularly paraffin-based PCMs, leading to greater depth of analysis for this category. Thermophysical properties are analyzed in conjunction with discharge rate, module configuration, and hybrid cooling strategies. The results indicate that peak temperature mitigation is weakly correlated with latent heat magnitude when thermal conductivity remains below critical values. Conductivity-enhanced composites incorporating expanded graphite or metal foams significantly improve heat diffusion, reducing hotspot intensity and inter-cell temperature gradients under medium-to-high C-rates. Pure passive PCM systems exhibit thermodynamic limitations during sustained high-power operation due to saturation effects, underscoring the need for hybrid architectures for continuous heat rejection. This work establishes a structured benchmarking framework and demonstrates that effective thermal conductivity, integration strategy, and discharge-dependent design dominate BTMS performance over latent heat alone. The findings also reveal that inorganic and eutectic PCM-based BTMSs remain comparatively less explored in the literature, particularly at the battery module level and under realistic electric vehicle operating conditions, highlighting opportunities for future research. Full article

The prevention and control of forest fires are of vital importance for ecological security. The efficiency and environmental friendliness of fire-extinguishing agents remain the core focus of current research. This paper reviews the research progress and fire extinguishing mechanisms of three types of forest-fire-extinguishing agents, namely, foam extinguishing agents, gel extinguishing agents, and fire-resistant barrier materials. These three types of extinguishing agents work together to extinguish fires through three principles: isolating combustibles, reducing the oxygen concentration, and lowering the temperature. This paper systematically summarizes the performance evaluation methods, covering the cooling rate, fire extinguishing time, and re-ignition rate, and combines numerical simulation and field experiments to build a multi-scale verification system. The environmental assessment focuses on biodegradability, the ecological toxicity to soil and water systems, and the impact on plant germination and biodiversity. It clearly indicates that degradability, low toxicity, and low residue are key development directions. The current research still needs to further deepen in aspects such as long-term stability, adaptability to complex terrains, and ecological risk assessment during the life cycle. In the future, priority should be given to promoting green, multi-functional, and precise application technologies to provide solid support for scientific forest fire prevention and ecological protection. Full article

Coal spontaneous combustion remains a major threat to underground coal-mine safety, resource recovery, and environmental protection. Foam-based materials have attracted increasing attention because they integrate wide-area coverage, oxygen isolation, evaporative cooling, active inhibition, and adaptability to fractured or leakage-prone goaf environments. However, existing studies are dispersed among different foam systems, and the relationships among formulation design, suppression mechanisms, performance indicators, and engineering applicability remain insufficiently clarified. This review summarizes recent advances in two-/three-phase foams, gel foams, inhibitor foams, and solidified foams for coal spontaneous-combustion prevention. Unlike reviews focused on a single material type, this work develops a comparative framework linking material composition, dominant mechanisms, key performance indicators, field applicability, and environmental compatibility. Representative components, preparation routes, suppression mechanisms, quantitative performance data, engineering cases, and limitations are compared. The main challenges include high-temperature structural degradation, limited adaptability to heterogeneous leakage pathways, incomplete multi-parameter evaluation systems, and potential ecological risks. Future research should focus on multifunctional and environmentally benign formulations, improved high-temperature durability, standardized laboratory–field evaluation methods, and scenario-oriented material selection for large-scale mine applications. Full article

Thermal tactile perception plays a crucial role in enhancing realism and immersion in human–machine interaction, virtual/augmented reality, and wearable systems. By exploiting the thermoelectric effect to achieve precisely controllable heating and cooling, wearable thermoelectric devices (WTEDs) offer an effective approach for generating localized and programmable thermal sensations, which calls for a clear understanding of skin temperature regulation mechanisms. In this work, a dynamic thermal conduction model is developed for a skin–WTED integrated system incorporating a nickel foam-reinforced hydrogel heat sink, based on the dual-phase lag (DPL) bioheat conduction theory. The model accounts for blood perfusion and metabolic heat generation in skin tissue, as well as the Thomson effect within the thermoelectric legs and convective heat losses from their side surfaces. The theoretical predictions are validated through human skin temperature regulation experiments using a fabricated WTED, showing close agreement between experiments and simulations and confirming the model’s accuracy and reliability. Based on the validated model, the cooling current, filling factor, and thermoelectric leg height are optimized by minimizing the skin surface temperature. Furthermore, the model is applied to thermal tactile feedback studies, enabling the controlled reproduction of skin thermal sensations associated with common objects, including an iron block, a PMMA plate, and carbonated beverages packaged in aluminum cans and plastic bottles. Overall, this study provides a practical and predictive framework for understanding, optimizing, and applying WTEDs in thermal tactile feedback. Full article

The quality and integrity of aluminothermic rail welds are strongly governed by the thermal conditions involved during preheating, pouring and cooling stages of the process. In this study, a simplified numerical framework is presented, based on the finite volume method and implemented in the open-source software OpenFOAM^® version 7, to predict the heat transfer and solidification processes. Within this framework, the preheating stage is simulated by employing a heat flux profile derived from experimental measurements, while the mould filling stage is neglected under the assumption of instantaneous pouring of the molten metal. The steel–slag multiphase system is treated using the Volume of Fluid method, whereas melting and solidification are captured using the enthalpy-porosity approach on a fixed Eulerian grid. The numerical framework is validated for a rapid welding process with short preheating procedure, consistent with typical industrial practice for rail welding. The predicted temperature histories during the preheating stage show sufficiently good agreement with the experimental measurements. Subsequently, the cooling stage is validated for a molten metal temperature of 2200 $°\mathrm{C}$ (≈2473 K). The predicted width of the fusion zone is compared with experimental data, showing reasonably good agreement in the railhead region, while an underestimation is observed in the rail web and rail foot regions. Furthermore, a systematic parametric investigation is conducted by varying two key process parameters, namely the molten metal temperature examined at four distinct levels ranging from 1800 $°\mathrm{C}$ (≈2073 K) to 2400 $°\mathrm{C}$ (≈2673 K), and the active preheating duration, varied across six values ranging from 90 $\mathrm{s}$ (1.5 min)–390 $\mathrm{s}$ (6.5 min), in order to assess their influence on the cooling stage. The numerical results provide detailed insight into the temporal evolution of the thermal field and its influence on the formation and extent of the fusion zone and heat-affected zone. The results demonstrate that, despite simplifications, the model captures the dominant thermal phenomena of the process and offers a computationally efficient tool for parameter studies and process optimisation. Full article

Integrating a heat exchanger (HEX) into the cooling duct of a high-power fuel-cell-based aircraft presents a critical trade-off between thermal performance and aerodynamic penalties. The present study addresses this challenge through the design and system-level analysis of a HEX integrated into the cooling duct. Developed as part of the Clean Aviation project FAME, the design features a rectangular inlet, a circular outlet, and a tilted HEX. The evaluation is performed using high-fidelity Large Eddy Simulations (LESs). The HEX is modeled with a porous media approach based on the Darcy–Forchheimer equation, while the simulations are carried out using a self-adapted version of the pisoFoam solver, termed pisoTempFoam, to account for heat transfer. The study reveals that while component-level design choices, such as a straight inlet and tilted HEX configuration, successfully mitigate local flow separation and duct-induced losses, a critical system-level performance issue emerges. The analysis demonstrates that the cooling duct design, when subjected to realistic operational conditions, generates the high pressure head to overcome the resistance of the HEX. The external aerodynamic analysis also indicates that the HEX resistance is a critical factor, and without overcoming it the system fails to capture the required air mass flow rate, compromising thermal management. The findings highlight the necessity to optimize the design, by an adapted duct shape or an auxiliary fan, to overcome the HEX-induced pressure drop. The porous media approach is thereby validated as an effective tool for rapid system-level design analysis, despite its inherent limitation in capturing detailed downstream turbulence. Full article

This study investigates how outlet pressure influences the fire suppression performance of a compressed air foam system (CAFS), with the aim of supporting system optimization and engineering applications. An experimental apparatus for foam performance testing is used to measure changes in foam flow rate, expansion, initial velocity, initial momentum, and drainage time at different outlet pressures. On the basis of relevant theoretical models, the factors causing discrepancies between model predictions and experimental results are examined, and the models are then refined. How the outlet pressure of CAFS affects foam performance is thereby clarified. The results show that foam flow rate increases as outlet pressure increases. At higher pressures, shear-thinning and intensified gas–liquid mixing affect the foam. As a result, the growth of flow rate in the range of 0.01–0.03 MPa is significantly higher than that in the range of 0.06–0.10 MPa. Both initial velocity and initial momentum increase significantly with increasing pressure, whereas the expansion decreases. Within the outlet pressure range of 0.01–0.10 MPa, the initial velocity increases from 1.23 m/s to 6.65 m/s, the initial momentum rises from 4.6 kg·m/s to 34.1 kg·m/s, and the expansion decreases from 9.2 to 5.4, indicating reduced foam stability. Drainage time and drained mass vary non-monotonically with outlet pressure. The longest drainage time and the smallest drained mass occur at 0.06 MPa. Fire suppression performance improves as outlet pressure increases. A higher outlet pressure enables the foam solution to penetrate the flame zone more effectively and to cover the surface of the burning material. In addition, changes in foam properties enhance the thermal insulation and smothering effects of the foam layer, as well as its heat absorption and cooling capacity. These effects together improve the efficiency of fire source cooling. Full article

Rapid urbanization has significantly increased energy demand in buildings, which now represent nearly 30% of global energy use. In India, buildings are built across highly varied climatic conditions, from hot-dry and warm-humid to cold, high-altitude areas, making climate-responsive envelope design essential to enhance thermal performance. Among envelope components, roofs are the most exposed to solar and outdoor thermal loads, playing a key role in managing indoor heat transfer. This study offers a parametric analysis of climate-responsive roof design strategies for India’s five main climatic zones, using transient simulations and statistical evaluation. The effectiveness of insulation placement, insulation material and thickness, and external surface absorptivity was systematically assessed based on roof heat gain and heat loss. Results indicate that over-slab insulation can lower roof heat gain by approximately 15–35% compared to under-slab insulation in warm-humid, hot-dry, composite, and temperate zones. In comparison, under-slab insulation decreases heat loss by about 10% in colder areas. Among insulation materials, 50 mm polyurethane foam (U = 0.433 W/m²·K) consistently outperformed extruded polystyrene and expanded polystyrene, achieving 82–83% reductions in maximum heat gain in cooling-dominated climates and 89% reductions in heat loss in cold regions relative to uninsulated roofs. When combined with a white reflective surface finish (α = 0.26), the total heat transfer reduction increased further to 89–92%. Surface treatments alone cut heat gain by 37–51% in non-cold climates, highlighting their potential as cost-effective retrofit options. Statistical analysis confirmed that dry-bulb temperature is the primary climatic factor influencing roof heat transfer (R² = 0.86–0.98, p < 0.0001), while solar radiation had a weaker effect, especially in optimized roof systems. The findings emphasize the importance of climate-specific roof design and demonstrate that insulation U-value has a greater impact on thermal performance than surface absorptivity, although both are significant. This research offers practical, climate-adjusted guidance for architects, engineers, and policymakers to enhance the thermal performance of roofs in Indian buildings. It supports the development of more resilient, energy-efficient building envelopes. Full article

To meet the miniaturized cooling demands of high-heat-flux electronic devices, metal foams—featuring high specific surface area and multiscale porous structures—are considered promising candidates for enhancing flow boiling evaporation. However, pore density (PPI) and grooved geometry (channel aspect ratio, AR) jointly regulate vapor–liquid distribution, rewetting, and flow resistance, thereby constraining overall performance. Here, flow boiling experiments were conducted on nickel and copper foams with pore densities of 100, 500, and 1000 PPI and AR values of 0.7, 1.0, and 1.3. Heat transfer coefficient (HTC), wall superheat ($\mathsf{\Delta }T$), and pressure drop ($\mathsf{\Delta }p$) were systematically evaluated, complemented by transient two-phase simulations revealing vapor fraction, temperature, and pressure drop distributions. A pronounced non-monotonic pore-density dependence is observed: 500 PPI achieves an optimal balance between heat-transfer enhancement and flow resistance, whereas 100 PPI suffers from vapor accumulation and temperature non-uniformity, and 1000 PPI is penalized by excessive permeability resistance and pore-scale confinement. An optimal AR of 1.0 promotes efficient vapor venting and stable rewetting. Under the optimal configuration (500 PPI, AR $=1.0$), a limiting heat flux of 348.6 W/cm², corresponding to the HTC of 55.4 kW/(m² · K), and a limiting HTC of 130.3 kW/(m² · K) are achieved, providing quantitative design guidelines for metal-foam two-phase evaporators. Full article