Double-layer Material Research Articles

Double-layered phase change material microcapsules with enhanced solar thermal conversion performance and fire safety for buildings

Building energy saving is directly related to resource utilization optimization and residential comfort, which is important for the environment and production. At present, building energy saving is developing towards green, recyclable, and low-risk directions. Phase change materials, as effective energy storage materials, can pollution-freely regulate room temperature. Regarding the leakage, phase change materials are encapsulated into microcapsules. However, the flammability and slow thermal response of phase change material microcapsules hinder their application in building materials. Herein, novel double-layered phase change material microcapsules (D-MPCMs), with the inner poly melamine tetramethylene phosphonium sulfate (PMTMPS) shell layers and outer polydopamine (PDA) shell layers, are prepared by in-situ polymerization method, which are filled into epoxy resin (EP) coatings. This study is the first to use cross-linked flame retardants as the shells of microcapsules. The outer PDA shell layer improves the flame retardancy of microcapsules while overcoming the problem of slow thermal response rate. Thermogravimetric analysis and differential scanning calorimeter tests are considered to explore the thermal stabilities and properties of the resultant microcapsules. Results demonstrate that D-MPCMs have a residual mass of 10.8 % more at 600 ℃ and a faster thermal response rate. The study shows that the addition of the PDA shell layers not only reduces the total heat release from 64.29 MJ/m2 to 45.01 MJ/m2 but also enhances the solar thermal conversion performance which gives potential in the process solar energy storage design and fire safety design in actual building application of epoxy resin coatings.

In Situ Construction of Bimetallic Selenides Heterogeneous Interface on Oxidation-Stable Ti3C2Tx MXene Toward Lithium Storage with Ultrafast Charge Transfer Kinetics.

Ti3C2Tx (MXene) is widely acknowledged as an excellent substrate for constructing heterogeneous structures with transition metal chalcogenides (TMCs) for boosting the electrochemical performance of lithium-ion storage. However, conventional synthesis strategies inevitably lead to poor electrochemical charge transfer due to Ti3C2Tx-derived TiO2 at the heterogeneous interface between Ti3C2Tx and TMCs. Here, an innovative in situ selenization strategy is proposed to replace the originally generated TiO2 on Ti3C2Tx with metallic TiSe2 interphase, clearing the bottleneck of slow charge transfer barrier caused by MXene oxidation. The construction of bimetallic selenide formed by CoSe2 and TiSe2 generates intrinsic electric fields to guide the fast ion diffusion kinetics in a heterogeneous interface. Additionally, the CoSe2/TiSe2/Ti3C2Tx heterogeneous structure with enhanced structural stability and improved rate performance is confirmed by both experiments and theoretical calculations. The engineered heterogeneous structure exhibits an ultra-high pseudocapacitance contribution (73.1% at 0.1mVs-1), rendering it well-suited to offset the kinetics differences between double-layer materials. The assembled lithium-ion capacitor based on CoSe2/TiSe2/Ti3C2Tx possesses a high energy density and an ultralong life span (89.5% after 10000 times at 2Ag-1). This devised strategy provides a feasible solution for utilizing the performance advantages of MXene substrates in lithium storage with ultrafast charge transfer kinetics.

Double layer bacterial nanocellulose - poly(hydroxyoctanoate) film activated by prodigiosin as sustainable, transparent, UV-blocking material

Synthetic materials alternatives are crucial for reaching sustainable development goals and waste reduction. Biomaterials and biomolecules obtained through bacterial fermentation offer a viable solution. Double-layer active UV-blocking material composed of bacterial nanocellulose as an inner layer and poly(hydroxyoctanoic acid) containing prodigiosin as an active compound was produced by layer-by-layer deposition. This study referred the new material consisted of the three components produced in sustainable manner, by bacterial activity: bacterial bio-pigment prodigiosin, bacterial nanocellulose and poly(hydroytoctanoate) - biopolymer obtained by microbial fermentations. Prior the final double layer film was produced, PHO films containing different PG concentrations as a layer in charge of the bioactivity (0.2, 0.5 and 1 wt%) was casted and systematically characterized (FTIR, DSC, XRD, wettability, SEM, transparency, mechanical tests) to optimize their properties. The formulation with the best UV-blocking properties and less toxicity effect tested using MRC5 cells was chosen as an outer layer in double-layer films production. Water contact angle measurements confirmed that hydrophilic – hydrophobic double layer film was obtained with the improved mechanical properties in comparison to the native BNC. Migration test indicated release of PG in all tested media as a consequence of bilayer formulation, while the PG release from PHO in 10 % ethanol was not detected. All findings from the study suggested this activated, UV-blocking material as a candidate with excellent potential in packaging industry.

Architected Carbon Structures for Energy Storage

Carbon materials, owing to their excellent electrical conductivity, tailor-ability, inexpensiveness, and versatility, have been extensively studied as electrode materials for energy storage devices, including batteries and supercapacitors. In this talk, I will discuss how to combine conventional materials/chemical synthesis with 3D printing techniques to develop architected carbon electrode materials for supercapacitors. The capacitance of carbon-based supercapacitor electrodes has remained at a mediocre level between 100 and 200 F/g for decades. Until recently, a new family of carbon materials termed hierarchical porous carbons has pushed the capacitance to new benchmark values beyond 300 F/g and has revitalized the exploration of carbon materials for supercapacitors. We have recently developed some hierarchical porous carbon areogels contain different scales of pores inter-connected together and assembled in hierarchical patterns, through a combination of freeze drying, template, chemical etching and 3D printing. These porous carbons have an open porous structure, providing an extremely large and accessible surface area. They can be used as electric double layer materials that enable ultrafast charging/discharging and retain outstanding capacitive performance even at ultralow temperatures (-70 °C). They can serve as 3D conductive scaffolds/current collectors to support pseudo-capacitive materials with ultrahigh mass loadings. These findings exemplified how to use a deterministic structure to improve the rate capability of supercapacitors and their capacitances at ultrahigh current densities and mass loadings and ultralow temperatures, which are long-standing challenges for SCs.

Design of a double-layered material as a long-acting moisturizing hydrogel-elastomer and its application in the field protection of elephant ivories excavated from the Sanxingdui Ruins.

The sudden change in the environment from a dark, low-oxygen, low-temperature, high-humidity underground stable environment to an environment with much-improved temperature and humidity, a high oxygen content, enhanced light exposure, and increased harmful organisms has greatly affected the stability of the ivory unearthed from the Sanxingdui site. Therefore, the implementation of an effective emergency protection strategy for ivory excavated at Sanxingdui is imperative and urgently needed. However, the current gauze technique used at many archaeological sites suffers from short timescales, poor transparency of the material, and susceptibility to reverse osmosis of the ivory. Therefore, in this study, a transparent poly(acrylamide-acrylic acid) (P(AM-AA)) hydrogel-poly(dimethylsiloxane) (PDMS) elastomer bilayer was designed for the effective protection of excavated ivory. In this system, a hydrophobic PDMS elastomer was constructed on the surface of the hydrogel by the introduction of a silane coupling agent to inhibit the loss of water from the hydrogel to the external environment, thus prolonging the preservation of ivory by the protective material. The covalent interface between the hydrogel and the elastomer allowed the double-layer composite to exhibit excellent interfacial bonding. In addition, the double-layer material demonstrated a high mechanical strength of 1.2 MPa and a water binding ratio of ∼31%, which allowed it to form strong hydrogen bonds with the silanol structure. When the hydrogel was placed in an air environment (temperature: 25 °C; relative humidity: 65% RH), the water-retention rate of the double-layer material was still more than 60% after 5 days, thus the double-layer material showed excellent performance. Meanwhile, the double-layer material had a transmittance of more than 90% and exhibited a high degree of transparency, which makes it possible to promptly observe the changes occurring on the surface of the ivory. The combination of the aforementioned properties makes the bilayer a promising material for moisturizing and protecting excavated ivory in situ. Based on these properties, we used the prepared P(AM-AA)/PDMS double-layer material directly for wrapping the K8 ivory with the highest water content at Sanxingdui. The weight retention rate of the ivory was around 70% after 50 days of placement (temperature: 25 °C; relative humidity: 60% RH), the macroscopic morphology did not change significantly and the mechanical properties of the wrapped ivory were basically unchanged, which indicated that the double-layer material has an excellent on-site protection effect on the ivory excavated from Sanxingdui. This work provides new ideas and methods for the temporary conservation of wet heritage.

High reflectivity and latent heat synergetic TiO2/Cs0.33WO3-PU double-layer materials with zero transmittance

Passive Cooling Technology, as a method of achieving long-term refrigeration without the need for external energy input, has emerged as an alternative to traditional energy-intensive cooling, garnering increasing attention from academia and industry. However, current passive cooling technology faces challenges such as incomplete solar energy reflection, overcooling, and inevitable absorption of solar radiation and surrounding environmental heat. This paper presents a passive cooling bilayer film with latent heat storage capability, composed of a solid–solid phase change polyurethane (PU) matrix with added TiO2 and Cs0.33WO3.TiO2/Cs0.33WO3-PU exhibits minimal solar transmittance, with reflectance and emissivity rates of 84.46 % and 93.08 %, respectively. The solid–solid phase change matrix effectively mitigates overcooling and heat input issues, reducing temperature fluctuations and peaks, and thereby enhancing passive cooling performance. At the phase transition temperature (306 K), TiO2/Cs0.33WO3-PU achieves cooling powers of 113.77 W/m2(day time) and 173.19 W/m2(night time), the temperature can be reduced by 14.3 °C under 100 mW/cm2sunlight. Additionally, TiO2/Cs0.33WO3-PU demonstrates outstanding thermal stability and reliabitity, hydrophobicity, as well as resistance to UV aging. Moreover, it offers the flexibility to adjust the phase transition temperature and latent heat of the solid–solid phase change matrix according to specific environmental conditions. TiO2/Cs0.33WO3-PU combines passive cooling materials with phase change materials, and complements each other’s advantages. TiO2/Cs0.33WO3-PU not only improves the cooling power, but also provides a new solution to the problem of heat input and supercooling of passive cooling materials. TiO2/Cs0.33WO3-PU also provides new possibilities for the application of passive cooling materials in the fields of long-term outdoor building cooling, human heat management, food preservation and electrical equipment cooling.

Improved Performance of Inverted Near-Infrared Organic Photodetectors Based on ZnO/PFN as Double-Layer Interfacial Materials

Improved Performance of Inverted Near-Infrared Organic Photodetectors Based on ZnO/PFN as Double-Layer Interfacial Materials

A bacterial cellulose/polyvinyl alcohol/nitro graphene oxide double layer network hydrogel efficiency antibacterial and promotes wound healing

In this study, graphene oxide (GO) was chemically modified utilizing concentrated nitric acid to produce a nitrated graphene oxide derivative (NGO) with enhanced oxidation level, improved dispersibility, and increased antibacterial activity. A double-layer composite hydrogel material (BC/PVA/NGO) with a core-shell structure was fabricated by utilizing bacterial cellulose (BC) and polyvinyl alcohol (PVA) binary composite hydrogel scaffold as the inner network template, and hydrophilic polymer (PVA) loaded with antibacterial material (NGO) as the outer network. The fabrication process involved physical crosslinking based on repeated freezing and thawing. The resulting BC/PVA/NGO hydrogel exhibited a porous structure, favorable mechanical properties, antibacterial efficacy, and biocompatibility. Subsequently, the performance of BC/PVA/NGO hydrogel in promoting wound healing was evaluated using a mouse skin injury model. The findings demonstrated that the BC/PVA/NGO hydrogel treatment group facilitated improved wound healing in the mouse skin injury model compared to the control group and the BC/PVA group. This enhanced wound healing capability was attributed primarily to the excellent antibacterial and tissue repair properties of the BC/PVA/NGO hydrogel.

Interdigitated supercapacitor with double-layer active material prepared by sacrificial layer method

Increasing the surface area of active materials is a crucial approach to enhance the capacity of supercapacitors. In this study, we present an interdigitated supercapacitor featuring a double-layer active material prepared using a sacrificial layer method. The replacement of the insulating substrate with a gel electrolyte facilitates ion motion between the active electrodes. Finite element analysis (FEA) and electrochemical experiments confirm that the utilization of double-layer active material can significantly improve the capacity (1.5–1.85 times higher than traditional structures). The electrochemical performance of the three active materials has been significantly improved after using the double-layer active material structure, which proves that the method in this paper has strong material compatibility. Furthermore, an interdigital supercapacitor (ISC) is fabricated using electrodes with double-layer active material through the sacrificial layer method and its electrochemical performance is evaluated. At a scan rate of 10 mV·s-1, ISC exhibits an impressive area-specific capacitance as high as 68.4 mF·cm-2. Remarkably, ISC can maintain stable power output even under extreme deformation and fatigue testing conditions. This strategy involving interdigitated supercapacitors with double-layer active materials prepared via the sacrificial layer method presents a promising solution for flexible energy storage devices.

Confined grotthuss proton-conduction along polyoxometalate chains inside carbon nanotubes for high-rate charge storage

Redox-active materials with excellent rate capability and cycling performance are in highly demand for electrochemical energy storage and conversion applications. Here, we unveil the confined proton-conduction behavior of one-dimensional polyoxometalate chains inside single-walled carbon nanotubes (SWNTs). The polyoxometalate molecules including phosphomolybdic acid {HPMo} and phosphotungstic acid {HPW} are encapsulated within SWNTs via host–guest recognition, driven by the electron transfer from nanotubes to polyoxometalates. Impressively, the redox hybrids of polyoxometalate@SWNTs deliver abnormal rate performance in acidic solution with capacity retentions over 73 % at high sweep rate of 1000 mV s−1, relative to the capacity at 10 mV s−1. This value is comparable to that of the pure SWNTs, typically known as double-layer capacitive materials. Electrochemical analyses reveal the Grotthuss proton-conduction mechanism of {HPMo} in SWNTs with a low activation energy of 0.11 eV. Therefore, the {HPMo}@SWNT hybrid demonstrates quasi diffusion-free characteristic with dominant capacitive contribution over 60 % at different sweep rates. Molecular dynamic simulations and density functional theory calculations evidence the strong burst-like transport of protons in the {HPMo}@SWNT hybrid. This process is dynamically favored in the continuous and long-range hydrogen-bond network along polyoxometalate chains with bound/free water molecules inside SWNTs. The superiority of nanoconfined Grotthuss mechanism may engender an exciting avenue for developing high-performance energy storage materials.

Fluid–Solid Mixing Transfer Mechanism and Flow Patterns of the Double-Layered Impeller Stirring Tank by the CFD-DEM Method

The optimization design of the double-layered material tank is essential to improve the material mixing efficiency and quality in chemical engineering and lithium battery production. The draft tube structure and double-layered impellers affect the flow patterns of the fluid–solid transfer process, and its flow pattern recognition faces significant challenges. This paper presents a fluid–solid mixing transfer modeling method using the CFD-DEM coupling solution method to analyze flow pattern evolution regularities. A porous-based interphase coupling technology solved the interphase force and could be used to acquire accurate particle motion trajectories. The effect mechanism of fluid–solid transfer courses in the double-layered mixing tank with a draft tube can be obtained by analyzing key features, including velocity distribution, circulation flows, power, and particle characteristics. The research results illustrate that the draft tube structure creates two major circulations in the mixing transfer process and changes particle and vortex flow patterns. The circulating motion of the double-layered impellers strengthens the overall fluid circulation, enhances the overall mixing efficiency of the fluid medium, and reduces particle deposition. Numerical results can offer technical guidance for the chemical extraction course and lithium battery slurry mixing.

The sound absorption properties of a double-leaf micro perforated panel (DL-MPP) made from a double-layered polypropylene material.

Micro-perforated panel sound absorbers are recognized as an alternative method for noise control, offering advantages over conventional porous absorbers. However, the sound absorption of a single micro-perforated panel (MPP) is limited in its ability to cover a broad range of frequencies, especially in the low-frequency region. Therefore, the primary focus of this study is to investigate the sound absorption performance of a double-leaf micro-perforated panel (DL-MPP) absorber, which aims to achieve high sound absorption across a wide frequency range. This study examines the impact of varying parameters, including perforation ratio, diameter of perforated holes, and air gap thickness, on the sound absorption characteristics of a polypropylene-based DL-MPP absorber. Polypropylene was used as the sound absorption material for this investigation. The DL-MPP absorber consists of two perforated panels installed parallel to a rigid back wall, with an air gap between them. To assess the sound absorption performance, a prototype of the DL-MPP absorber was fabricated and tested using a two-microphone impedance tube method following ASTM E1050 standard. The results demonstrate that the optimal sound absorption performance was achieved by designing the MPPs with a 1% perforation ratio, 1 mm diameter of perforated holes, and a 1 mm sample thickness.

Tunable valley splitting in RuClF bilayer

Valleytronic devices are increasingly gaining attention for their unique capability to encode and process information by leveraging electronic valley degrees of freedom. In this study, we performed first-principle calculations to analyze the band dispersions of double-layer antiferromagnetic valley material RuClF subjected to an external electric field. Our findings show that the double-layered structure exhibits interlayer antiferromagnetic order and that the bilayer bands display opposite valley splitting. We further categorized the atomic contact surfaces of the top and bottom layers into three interface conditions: F/F, Cl/Cl, and Cl/F. Under F/F and Cl/Cl interface conditions, when the electric field changes by 0.1 V/nm, the valley splitting values change by 12.2 meV and 9.5 meV, respectively. However, under the Cl/F interface condition, the structure exhibited metallic characteristics and was as such excluded from our analysis. These findings substantiate the practicality of employing an electric field to regulate the valley splitting of the bilayer structure, offering a new control strategy for valleytronic devices.

Protonated C3N4 Nanosheets for Enhanced Energy Storage in Symmetric Supercapacitors through Hydrochloric Acid Treatment.

Next-generation electrochemical energy storage materials are essential in delivering high power for long periods of time. Double-layer carbonaceous materials provide high power density with low energy density due to surface-controlled adsorption. This limitation can be overcome by developing a low-cost, more abundant material that delivers high energy and power density. Herein, we develop layered C3N4 as a sustainable charge storage material for supercapacitor applications. It was thermally polymerized using urea and then protonated with various acids to enhance its charge storage contribution by activating more reaction sites through the exfoliation of the C-N framework. The increased electron-rich nitrogen moieties in the C-N framework material lead to better electrolytic ion impregnation into the electrode, resulting in a 7-fold increase in charge storage compared to the pristine material and other acids. It was found that C3N4 treated with hydrochloric acid showed a very high capacitance of 761 F g-1 at a current density of 20 A g-1 and maintained 100% cyclic retention over 10,000 cycles in a three-electrode configuration, outperforming both the pristine material and other acids. A symmetric device was fabricated using a KOH/LiI gel-based electrolyte, exhibiting a maximum specific capacitance of 175 F g-1 at a current density of 1 A g-1. Additionally, the device showed remarkable power and energy density, reaching 600 W kg-1 and 35 Wh kg-1, with an exceptional cyclic stability of 60% even after 5000 cycles. This study provides an archetype to understand the underlying mechanism of acid protonation and paves the way to a metal-carbon-free environment.

Analysis Study of Thermal and Exergy Efficiency in Double-Layers Porous Media Combustion Using Different Sizes of Burner: A Comparison

Experimental investigations are currently exploring the impact of adding porous layers within burner housing on thermal and exergy efficiency. Specifically, the focus is on understanding the significance of double layers on porous media combustion and how it can improve fuel mixing and flame stability. Premixed butane-air combustion in rich conditions was examined using three different sizes of burners (i.e., 23 mm, 31 mm, and 44 mm) porous media with equivalence ratios ranging from ф = 1.3 to 2.0. The experimental findings revealed a substantial improvement in performance efficiency (thermal and exergy) as the equivalence ratio increased. This study reveals that smaller burner diameters (ID, inner diameter = 23 mm) provide greater efficiency than larger ones (ID = 31 mm and 44 mm). The maximum flame temperature and porous wall temperature are found to decrease as the equivalence ratio increases. The highest temperature measured was 924.82°C for 23 mm, 910.23°C for 31 mm, and 850.76°C for 44 mm at ф = 1.3. Lastly, the thermal and exergy efficiency in a 23 mm porous media burner (PMB) is higher at ф = 2.0 at 84.30% and 83.47%, respectively. It can be concluded that the diameter size of the burner and equivalence ratio for double-layer porous material influence the performance (efficiency) of PMB.

Tunable broadband near-infrared emission from environmentally friendly Fe3+-activated lead-free perovskites for spectral analysis and rapid nighttime recognition

With the increasing role of near-infrared (NIR) light sources in many fields such as food and industry, NIR emitting phosphors have flourished in recent years. In addition to the widely reported Cr3+-activated NIR phosphors, environmentally friendly Fe3+ can also produce tunable broadband NIR spectra, which are expected to enrich the next generation of intelligent NIR light sources. In this work, a series of Fe3+-activated perovskite-type Sr2ScSbO6 (SSSO) NIR phosphors were successfully prepared and an emission wavelength of 900 nm with a full width at half maximum (FWHM) of 110 nm was obtained. Through the crystal field engineering strategy, the lattice site of Sr2+ was completely replaced by Ba2+ and Ca2+ to obtain Ba2ScSbO6 (BSSO) and Ca2ScSbO6 (CSSO), and the emission peak was continuously adjusted from 840 nm to 950 nm. When the temperature increased from 300 K to 400 K, BSSO:Fe3+, SSSO:Fe3+ and CSSO:Fe3+ could maintain 69 %, 82 % and 67 % of the original luminescence intensity, respectively. The opposite crystal field dependence between Fe3+ and Cr3+ was shown in double-layer perovskite-type antimonate materials, which could guide us to develop Fe3+-activated long-wavelength emission NIR phosphors. Benefiting from the long-wavelength emission of BSSO:Fe3+, SSSO:Fe3+, and CSSO:Fe3+, their application potential in the field of spectral analysis and rapid nighttime recognition were successfully demonstrated.

Thermal contact analysis of Flip-Chip package considering microscopic contacts of double-layer thermal interface materials

Flip-chip packaging technology is widely used in the field of electronic packaging. The thermal contact resistances (TCRs) of its double-layer thermal interface materials (TIMs) impact its thermal characteristics. In this paper, a flip-chip package thermal contact model is first constructed considering the internal rough contact interface of double-layer TIMs. Secondly, the effects of friction coefficient, pressure, elastic modulus of double-layer TIMs, thermal conductivity of double-layer TIMs, interstitial medium, and convective heat transfer coefficient on the flip chip package's contact mechanics and thermal properties are analyzed. Finally, the influence of secondary thermal effects on contact mechanics and thermal properties is investigated. The results show that the friction coefficient, pressure, and elastic modulus of double-layer TIMs have a significant influence on the TCRs by changing the actual contact area, but the impact on the heat dissipation of the chip is limited, and the maximum temperature reduction does not exceed 10 K. However, the interstitial medium, convective heat transfer coefficient, and thermal conductivity of double-layer TIMs greatly influence the heat dissipation of the chip and maximum temperature by directly affecting heat transfer performance. Furthermore, secondary thermal effects have varying degrees of influence on contact stiffness, TCRs, and temperature distribution.

A low-profile metamaterial absorber with ultrawideband reflectionless and wide-angular stability

An ultrawideband reflectionless metamaterial absorber (MA) is proposed by replacing the metallic ground with the complementary split-ring resonator (CSRR) structure. The proposed MA exhibits −10 dB reflectivity spectrum from 1 GHz to 20 GHz, which maintains more than 90% absorption from 1.5 GHz to 20 GHz. Furthermore, it achieves angle stability for TE and TM polarization at oblique incident angles up to 40° and 65°, respectively. To achieve broadband absorption spectrum, we have adopted a single-layer high-impedance surface (HIS) loaded with a double-layer magnetic material (MM) structure. To further realize the RCS reduction into a lower frequency range, we have employed the scattering cancellation technology into the traditional metallic ground. Finally, we have fabricated a sample exhibiting the 10 dB RCS reduction from 1 GHz to 20 GHz with a thickness of 10 mm. Measurement and simulation results confirm that the proposed MA exhibits excellent comprehensive performance, making it suitable for many practical applications.

Impact of Geometric Parameters on Spring-Back Deformation in Double-Layer Metal Sheet Bending with an L-Shaped Die

This study delves into the intricate dynamics of the return deformation process in double-layer metal sheet stamping on an L-shaped die, focusing on the pivotal influence of punch and die size parameters. The specific parameters under scrutiny include die radius, die clearance, and plate length. Employing a comprehensive methodology, this research conducts finite element simulations using Abaqus software, ensuring both data collection requirements and implementation feasibility are met. The simulation results are rigorously compared with the published data from a seminal comparative study [1], providing a critical point of reference for analysis. The findings of this investigation illuminate a profound similarity in the impact of three critical parameters, namely die radius, degree of mold opening, and plate length, on the degree of spring-back deformation in the L-bending of SPCC double-layer materials. This outcome not only substantiates and extends the existing body of knowledge but also offers novel insights into the interplay of these parameters in the double-layer metal sheet stamping process, thus contributing significantly to the field of manufacturing and process optimization.

Enhancing the performance of solar water heating systems: Application of double-layer phase change materials

An efficiently designed thermal energy storage (TES) tank is critical for enhancing the efficiency of solar water heating systems (SWHSs). This study describes the development of a hybrid sensible-latent TES tank in which a double-layer phase change material (PCM) with different melting points is integrated. To study its performance, a mathematical model of the SWHS with the hybrid tank was established in TRNSYS software. The results showed that when the volume of tank per unit area of solar collectors was in the range of 33.3–66.7 L/m2, the heat collection of the hybrid tank increased by 7.0%–15.6% and the heat supply increased by 7.6%–16.9% compared to that of the tank without the PCM. However, the effect of adding the PCM to the tank diminished when the volume of the tank was increased. The hybrid tank with the double-layer PCM achieved a twofold benefit of extending the heat supply time and maintaining a relatively high supply temperature compared to the tank with only a single-layer PCM. The effect of the hybrid tank on the thermal performance of the SWHS was prominent for the full-day and nighttime heating modes but was not significantly observed for the daytime heating mode.