Double-layer System Research Articles

Energy efficiency and economic performance of a low-temperature heating system combining double-layer pipe-embedded wall and ground source heat pump

Reducing heating energy consumption in buildings is a crucial step towards a low-carbon future. The energy efficiency of heat pump heating systems can be improved by reducing the water supply temperature of terminals. However, existing terminals are limited in using lower-temperature hot water and leaves potential for energy savings. Therefore, this study proposes a double-layer pipe-embedded wall heating system coupled to a ground source heat pump. The outer pipes use shallow geothermal energy to reduce envelope load, whereas the inner pipes use water produced by the heat pump to provide heating. Energy, economic, and carbon emission analysis models of the proposed system are developed. A residential heating case study is conducted in Harbin, Shenyang, Beijing, Zhengzhou, and Shanghai to investigate the performance of the proposed system. The results show that the proposed system achieves much lower-temperature heating than the reference floor heating system. The seasonal energy savings of the proposed system in the selected cities are 12%–18%, with a SCOP of 4.0–5.8. The dynamic payback period of the proposed system is 1.6–4.3 years and the CO2 emission intensity is reduced by 1.2–3.2 kg/m2. This study provides an insight into the application of DPEW heating systems.

The construction of a double-layer colon-targeted delivery system based on zein-shellac complex and gelatin-isomaltooligosaccharide Maillard product: In vitro and in vivo evaluation

In this study, we developed a double-layer colon-targeted microcapsule. It used the Maillard product of gelatin-isomaltooligosaccharide (GI180) and zein-shellac complex (ZS) as bio-based materials, plant extracts (MPL) and Lactobacillus plantarum JJBYG12 (JJBYG12) were co-encapsulated, endowing them with strong resistance to harsh environments and precise intestinal adhesion and targeting ability. The research results indicated that ZS11 exhibits hydrogen bonding and electrostatic interactions. The encapsulation efficiencies of ZS11 for JJBYG12 and for polysaccharides, polyphenols, and flavonoids in MPL were 88.03 %, 73.40 %, 77.90 %, and 70.87 %, respectively. SEM and CLSM images showed that ZS11 has a dense double-layer structure. Simulation of in vitro gastrointestinal digestion showed that ZS11 can achieve sustained release, with a live bacterial count of 8.05 ± 0.004 Log CFU/mL reaching the colon. The SEM and fluorescence images at different stages of in vitro digestion also demonstrated the strong protective ability of ZS11. Studies conducted in mice had shown that ZS11 can successfully pass through the gastric stage and release probiotics in the distal ileum, cecum, and proximal colon (target intestinal segment). Finally, ZS11 had good storage stability and thermal stability. In summary, this study demonstrated the potential of dual-layer colon-targeted microcapsules for the co-delivery plant extracts and probiotics, providing ideas for developing new delivery systems with targeted therapeutic effects.

The energy consumption characteristics of a new type of energy dissipating vibration-damping fastener

To address the issue of inadequate energy dissipation capacity in current vibration-damping fasteners, this study examined the impact of stiffness and damping factor of vibration-damping fasteners on the vibration attenuation rate of rails, based on the theoretical model of a periodic double-layer support system. An intrinsic manganese–copper (Mn–Cu) damping alloy model was established, and the parameters for the Prony analysis and PRF model were determined to accurately define the hyperelastic and linear viscoelastic properties of the damping alloy in the finite element simulation software. A new type of energy dissipating vibration-damping fastener (NEDF) was designed based on these criteria and practical operational conditions. Static and dynamic stiffness simulation calculations were performed to examine the vibration isolation ability of NEDF, which was then installed in a rail system to conduct hammering tests, aiming to investigate its energy dissipation characteristics. The results indicated that NEDF exhibited a high damping factor and maintained significant vibration isolation capacity, notably enhancing the vibration attenuation rate of the rails and improving energy dissipation capacity.

Vibration isolation performance analysis of laminated double-layer rectangular plate structure

Based on the spectral geometry method, the analytical model of laminated double-layer rectangular plate including elastic floating raft damping system is established. The artificial virtual technology is used to simulate the elastic boundary conditions of the laminated deck, and the three-dimensional damping isolator and elastic raft plate are used to simulate the floating raft damping system. Based on energy principle, the solution equation of vibration characteristics of laminated double-layer rectangular plate system is obtained by Rayleigh Ritz method. Compared these results with finite element method, the reliability of the model is verified. Then the effects of different parameters on the dynamic characteristics of double plate structure are further discussed.

Study on the Shock-Absorption Performance of Isolation Systems in High-Rise Vertically Irregular Double-Story Structures

(1) Research background: The aim of this study was to explore the seismic response of vertically irregular high-rise buildings using a double-layer isolation system. (2) Methods: A 24-story vertically irregular high-rise frame-shear wall structure was designed, and the finite element model of the double-layer isolation structure was established, as well as the models of the seismic structure, the foundation isolation structure, and the story-separated seismic structure. A dynamic time–history analysis of these models under rare ground motion was carried out. (3) Results: The double-layer isolation system has the best isolation effect, followed by the foundation isolation structure, and finally the interlayer structure. The double-layer isolation system can increase the natural vibration period of the structure by 1.25 times, reduce the displacement angle of the layer by about 74.3%, reduce the acceleration of the top layer by about 82.3%, reduce the base shear force by about 59.68%, reduce the overturning moment of the bottom layer by about 68.89%, and reduce the torsion angle of the top layer by about 89.68%. (4) Conclusions: The double-layer isolation system can effectively reduce the overall seismic response of the structure and effectively control the torsional response of the structure, which makes it feasible for application.

Study on additional stress diffusion characteristics of waste tire artificial foundation

ABSTRACT The study of additional stress diffusion law in the artificial foundation has a significant importance for analysing the overall deformation mechanism of the ‘foundation + underlying soil’ coupled system. Through plate loading tests, the soil pressure within the foundation under various conditions was measured, and the corresponding P-S curves were obtained. By analysing the trend of P-S curves and evolution of the compressive stiffness, the failure mechanism of the Artificial Foundation and single column composite body was explained. The calculation methods for the interface rubber content ratio and modified volumetric rubber content ratio, which quantify the contact relationship between tires and soil and the interlocking relationship between tires, were provided. Through thin plate spline interpolation, an additional stress field was established, which demonstrate the impact of the rubber content on the diffusion shape of the additional stress. The results indicate that sliding of the underlying layer is the primarily failure mode of the double-layer foundation system. The necessary condition for the hoop effect vanishing is the adequacy of lower boundary stiffness. Compared to plain soil, the bearing capacities of the artificial foundations increase by 2.33–5.72 times. Laying geo-textile and geo-grid between layers can effectively enhance the initial compression stiffness and prolong the linear bearing phase. With an increase in rubber content, the additional stress diffusion angle increase by as much as 16.2% to 79.9%. Finally, a stress diffusion function was established by fitting the measured soil pressure values.

Thermal performance of a double-layer pipe-embedded phase change wall system in wood structures coupled with solar energy

In this study, we propose a dual-layer, pipe-embedded phase change wall system for wooden structures that integrates sky radiation cooling and solar heat collection for cross-seasonal operation. This system harnesses renewable energy and reduces the operational energy consumption of buildings. The primary focus of this study is the performance improving of the system during winter conditions. In winter, the system captures solar energy for daytime indoor heating and load reduction and stores excess heat in phase-change material (PCM) embedded within the wooden wallboard. The stored heat is then released at night to further reduce building loads. To assess the thermal performance of the proposed wall system under winter conditions, experiments were conducted across four different scenarios and a reference system was established for comparative analysis. The results indicate that the proposed wall system significantly improves the indoor thermal environment. Specifically, this integration increased the average indoor air temperature by 6.0 °C compared to the reference system and substantially increased the temperature of the wallboard. The inclusion of PCM notably enhanced the thermal performance by reducing nighttime heat loss. Consequently, the average indoor temperature in systems equipped with PCM-enhanced wallboards was 3.0 °C higher than that in the reference system.

Analysis of Galvanostatic Data from Electrochemical Capacitors

The ability to deconvolute charge storage mechanisms in electrochemical capacitor materials and systems is essential for understanding and improving behaviour. From an electrochemical perspective, this deconvolution can be achieved through an understanding of the expected response of a particular contribution. Voltametric measurements can be deconvoluted through the current response relative to the applied sweep rate. Herein we describe an analogous approach for galvanostatic data in which the charge or discharge time is related to the applied current (I). Specifically, capacitive charge storage is shown proportional to I−1, while diffusional processes are proportional to I2. Coupling this with a constant contribution from ohmic and residual charge storage processes allows for an effective approach to deconvolution for galvanostatic data. This is demonstrated with data from a glassy carbon electrode in non-aqueous electrolyte (an expected electrical double layer system) and from a manganese dioxide electrode in aqueous electrolyte (an expected pseudo-capacitive system).

Wind-induced response and control criterion of the double-layer cable support photovoltaic module system

The cable support photovoltaic module system has obvious characteristics of wind-induced vibration. In order to study the wind-induced vibration response characteristics and mechanism of the double-cable support photovoltaic module systems, and further discuss the stiffness control criterion. The wind-induced vibration response of a new type of cable-truss support photovoltaic module system with a span of 35m is studied through the aeroelastic wind tunnel test. Firstly, the scaled aeroelastic test model was established to meet the aeroelastic test requirements. Then, the effects of wind direction, PV module inclination angle, and stability cable initial prestress on the wind-induced vibration response characteristics under uniform flow and turbulent field are studied. Finally, the wind-induced vibration response mechanism and stiffness control criterion are discussed. The results show that the increase of inclination angle will lead to a decrease in critical wind speed, the 0° wind direction is the most unfavorable, and the increase of initial prestress can increase the critical wind speed but is inefficient. The critical wind speed under the turbulent flow field is about 30% higher than that of the uniform flow field. The instability vibration is the result of multi-mode coupled vibration of vertical bending and torsion. It is suggested that the stiffness control criterion is more appropriate as 1/100. The research results are of great significance for the design and application of the cable support photovoltaic module system.

Four-Dimensional Printing of Multi-Material Origami and Kirigami-Inspired Hydrogel Self-Folding Structures.

Four-dimensional printing refers to a process through which a 3D printed object transforms from one structure into another through the influence of an external energy input. Self-folding structures have been extensively studied to advance 3D printing technology into 4D using stimuli-responsive polymers. Designing and applying self-folding structures requires an understanding of the material properties so that the structural designs can be tailored to the targeted applications. Poly(N-iso-propylacrylamide) (PNIPAM) was used as the thermo-responsive material in this study to 3D print hydrogel samples that can bend or fold with temperature changes. A double-layer printed structure, with PNIPAM as the self-folding layer and polyethylene glycol (PEG) as the supporting layer, provided the mechanical robustness and overall flexibility to accommodate geometric changes. The mechanical properties of the multi-material 3D printing were tested to confirm the contribution of the PEG support to the double-layer system. The desired folding of the structures, as a response to temperature changes, was obtained by adding kirigami-inspired cuts to the design. An excellent shape-shifting capability was obtained by tuning the design. The experimental observations were supported by COMSOL Multiphysics® software simulations, predicting the control over the folding of the double-layer systems.

Heat transfer and stratification behaviors of internally heated double-layer fluids systems under swinging conditions

To evaluate the safety designs aimed at the stratified corium pools for nuclear reactors applied in the marine environment, it’s important to carry out research on the convection related phenomena inside a layered fluids system under motion conditions. Thus, in this paper, the macroscopic characteristics of heat transfer and stratification for the double-layer fluids systems with internal heat source under motion conditions were studied through visualization experiments, and due to the complexity of actual ocean motions, only swinging motions were considered. In this research, a new dimensionless number Ris was proposed to quantify the effects of swinging motions, which represents the ratio of the characteristic buoyancy to the characteristic centrifugal force caused by swinging motions. Based on experimental results, swinging motions exert the most significant impacts on the layered systems when Ris is less than 1. In this case, the ratio of maximum temperature fT and the ratio of temperature difference between the two layers fΔT both dropped below 0.5, while the ratio of peak heat transfer capacity fQ-peak raised above 1.5, with the ratio of stable heat transfer capacity fQ-stable most probably lying within the range of 1.06 to 1.2. Additionally, several representative types of macroscopic interface deformation or stratification instability was observed, and phenomenon of mixing could appear between the double-layer fluids under intense-enough swinging conditions. These phenomena imply the significantly intensified forced convection inside the layered systems, which explains the sharply decreased temperature difference and the greatly enhanced heat transfer capacity during high-intensity swinging motions. By contrast, when Ris becomes larger than 10, the values of fΔT、fΔT and fQ-peak will be approaching to 1.0, and relatively stable stratification of the layered systems can be maintained, which indicates the increasingly negligible impacts of swinging motions in such cases. Besides, it was found that an increase in the thickness of either the lower-layer or the upper fluid also helped restrain interface deformation and enhanced the stratification stability of the layered systems.

Numerical and experimental blast response of multilayer laminated glass panels

Laminated glass is used in high-security buildings to mitigate the effects of blasts and ballistic loadings. The multi-layered composition of the laminated glass (LG) panels allows the glass panes to crack and undergo large deflections while preventing glass shards from spalling by mostly remaining attached to the polymeric interlayer. To characterize multilayer LG panels under blast loading, it is essential to develop their static resistance response under uniform loading. A full-scale water chamber was used to experimentally evaluate the quasistatic response to the failure of the multilayer LG panel systems under uniform pressure. The influence of different polymeric interlayer types on the response of multilayer LG panels was studied. Also, the glass breakage patterns and deflections exhibited by various multilayer glass configurations were investigated. The response of LG panels under blast was developed using ANSYS AUTODYN, which was verified using field experiments. LG panels with an Ethylene Vinyl Acetate (EVA) polymeric interlayer experienced the most dynamic deflections, whereas LG panels with an ionoplast SentryGlas® (SG) polymeric interlayer displayed the least dynamic deflections. The results indicated that multilayer LG systems provide higher blast resistance compared to double-layer systems; the additional layers can help reduce glass breakage and maintain structural integrity. Multilayer LG system’s SG interlayer enhanced blast protection by allowing load transfer and ensuring uniform load distribution between glass layers.

COULOMB DRAG RESISTIVITY IN DOUBLE-LAYER GRAPHENE: INHOMOGENEITY EFFECTS

We investigate Coulomb drag resistivity in a double-layer system consisting of two parallel monolayer graphene sheets. In calculations, we employ the random-phase approximation to determine the polarizability functions of the graphene layers and the frequency-dependent dielectric function of the structure, taking into account inhomogeneity effects of the background dielectric. Our numerical calculations reveal that Coulomb drag resistivity in double-layer graphene systems steadily increases with increasing temperature but quickly decreases as the interlayer separation increases. The drag resistivity between the two layers in the case of an inhomogeneous background dielectric is substantially larger than that in the case of a homogeneous one. In addition, both the value and the imbalance in carrier density in the layers lead to noticeable changes in Coulomb drag resistivity in the system. Our study results are useful in graphene-based structure applications.

Experimental and simulation study of the effect of temperature and air supply on energy performance of a temperature-controlled ventilated double-layer Trombe wall

To study the energy performance of the temperature-controlled ventilated double-layer Trombe wall system (TCVD-TW) during winter and summer seasons, experiments and simulations were conducted in an experimental room in Qingdao where the system was installed. The experimental results demonstrate that the rooms equipped with this system exhibit favourable temperature performance in both winter and summer, with a positive impact on indoor humidity during the summer. The simulation results show that the performance of TCVD-TW is mainly affected by the supply air temperature, air volume flow rate, and indoor cooling and heating setpoints. For winter operating mode, the optimal supply air temperature setting should be 1°C higher than the heating setpoint. When the supply air temperature was set to 19℃(with a heating setpoint of 18 °C) and 21 °C (with a heating setpoint of 20 °C), the energy efficiency increased by 35.96 % and 32.38 %, respectively. When the supply air volume flow rate was set to 234 m3/h, the energy efficiency increased by 35.09 % (with a heating setpoint of 18 °C) and 30.27 % (with a heating setpoint of 20 °C), respectively. For summer operating mode, the optimal supply air temperature setting should be 1 °C lower than the cooling setpoint. When the supply air temperature was set to 25 °C (with a cooling setpoint of 26 °C), the energy efficiency improved by 33.62 %. When the supply air volume flow rate was set to 156 m3/h, the energy efficiency increased by 31.18 %. The experimental and simulation results of this study provide data support for the application of TCVD-TW.

Dual-layer probiotic encapsulation using metal phenolic network with gellan gum-tamarind gum coating for colitis treatment

Probiotic oral therapy has been recognised as an effective treatment for inflammatory bowel disease (IBD). However, the efficacy of probiotics is often diminished due to their limited resistance to harsh gastrointestinal conditions. Therefore, the importance of designing innovative strategies for oral probiotic delivery for the effective treatment of IBD is increasingly recognised. In this study, we present a novel encapsulation strategy of Lactobacillus plantarum (L.P) using the dual-layer system consisting of a tannic acid‑calcium network and polysaccharide coating (gellan gum-tamarind gum) named L.P-C/T-G/T. This double-layer encapsulation system not only does not affect the normal proliferation of probiotics and provide protection, but also endows probiotics with more functions. More specifically, the acid resistance ability of the encapsulated probiotics is increased by 10 times, the free radical scavenging rate is enhanced by 5 times, and the intestinal retention time can be prolonged by 6–12 h. In the DSS-induced murine colitis model, it significantly alleviated colon shortening, inhibited ROS overexpression, and promoted the repair and regeneration of the mucus layer. This dual-layer encapsulation approach for a single probiotic demonstrates a significant advancement in probiotic delivery technology, offering hope for a comprehensive approach to the treatment of colitis and potentially other gastrointestinal disorders.

Plasmon scattering at a junction in double-layer two-dimensional electron gas plasmonic waveguide

Abstract The scattering of plasmons at a junction within a double-layer two-dimensional electron gas plasmonic waveguide is studied via a full electromagnetic method. The dispersion relation is derived by utilizing the transfer matrix method and can be extended to the situation of an arbitrary number of layers. By numerically solving the dispersion equations, both the acoustic and optical plasmon modes are identified in this double layer system, and the unstable plasmon modes arising from plasmon coupling in different layers are discussed elaborately. Subsequently, the total fields are expanded with eigenmodes and matched at the interface to analyze the scattering characteristics at the junction. The results indicate that the total power of the plasmon mode is amplified when the electron fluid flows from a high concentration region to a low concentration region, and the amplification is more evident at a higher drift velocity. Additionally, we address the scattering of unstable plasmons caused by the two-stream instability and find that the transmitted plasmons are excited intensively at the incidence of the growing plasmon, leading to the plasmon amplification. The detailed examination of plasmon scattering at junction is the prerequisite for studying more complex structures of terahertz plasmonic devices and comprehending the corresponding amplification mechanism.

Development and characterization of a double-layer smart packaging system consisting of polyvinyl alcohol electrospun nanofibers and gelatin film for fish fillet

This study aimed to develop a double-layer film composed of an intelligent, gelatin-based film integrated with active polyvinyl alcohol electrospun nanofibers (PVANFs). Eggplant skin extract (ESE), a colorimetric indicator, was incorporated into the gelatin-based film at varying concentrations ranging from 0 % to 8 % w/w. The gelatin film containing 8 % ESE was identified as the optimal formulation based on its superior color indication, water barrier, and mechanical properties. Savory essential oil (SEO)-loaded PVANFs were electrospun onto the optimized gelatin film to fabricate the double-layer film. Analysis of the chemical and crystalline structures and the double-layer film's thermal properties confirmed the gelatin film's physical integration with PVANFs. Morphological examination revealed a smooth surface on the film and a uniform fibrillar structure within the PVANFs. Furthermore, the developed double-layer film effectively detected spoilage in trout fish while controlling pH, oxidation, and microbial changes during storage.

Plasmons and loss function in a double-layer silicene-graphene heterostructure at zero-temperature

We compute theoretically the plasmon frequencies and the loss function in a double layer silicene-graphene heterostructure within random phase approximation (RPA) at zero temperature. In the long wavelength approximation we obtain analytical expressions for the acoustic and optical plasmons as well as for the loss function restricted to the acoustic and optical plamon branches. In the q→0 limit the loss function restricted to the acoustic plasmon behaves as −ImTr[ΠR(q,ωac(q→0))]∼q while its restriction to the optical plasmon displays a behavior −ImTr[ΠR(q,ωop(q→0))]∼q32. Numerical simulations show that the acoustic plasmon crosses the ω=vFgq line tending towards the ω=12vFgq. To the best of our knowledge, this behavior is not exhibited in other double layer systems. Another novel feature of this system is that as the acoustic plasmon passes the ω=vFgq, the loss function restricted to the acoustic plasmon curve displays a highly concentrated peak with almost no broadening on a small interval until it disperses and shows the usual broadened peak for damped plasmons.

A Fuzzy Logic-Based Directional Charging Scheme for Wireless Rechargeable Sensor Networks.

Wireless Power Transfer (WPT) has become a key technology to extend network lifetime in Wireless Rechargeable Sensor Networks (WRSNs). The traditional omnidirectional recharging method has a wider range of energy radiation, but it inevitably results in more energy waste. By contrast, the directional recharging mode enables most of the energy to be focused in a predetermined direction that achieves higher recharging efficiency. However, the MC (Mobile Charger) in this mode can only supply energy to a few nodes in each direction. Thus, how to set the location of staying points of the MC, its service sequence and its charging orientation are all important issues related to the benefit of energy replenishment. To address these problems, we propose a Fuzzy Logic-based Directional Charging (FLDC) scheme for Wireless Rechargeable Sensor Networks. Firstly, the network is divided into adjacent regular hexagonal grids which are exactly the charging regions for the MC. Then, with the help of a double-layer fuzzy logic system, a priority of nodes and grids is obtained that dynamically determines the trajectory of the MC during each round of service, i.e., the charging sequence. Next, the location of the MC's staying points is optimized to minimize the sum of charging distances between MC and nodes in the same grid. Finally, the discretized charging directions of the MC at each staying point are adjusted to further improve the charging efficiency. Simulation results show that FLDC performs well in both the charging benefit of nodes and the energy efficiency of the MC.

Experimental study on a solar thermoelectric power generation system under non-uniform irradiation

Non-uniform irradiation caused by high light concentration significantly affects the performance of the solar thermoelectric power generation system, but the research remains at the theoretical stage. This paper establishes an experimental setup for the solar thermoelectric system and conducts a comprehensive experimental study of the system operating under non-uniform irradiation. The temperature, power and efficiency of the systems are tested for different input powers, cooling methods and structures, and irradiation uniformity. The results indicate that the output power of the solar thermoelectric system slightly increases and then decreases as the irradiation uniformity increases. The system’s output power is minimized when the irradiation uniformity approaches 100%. The optimum irradiation uniformity of the solar thermoelectric system is 47.4% and the maximum efficiency is 1.495%, which is an improvement of 7.6% compared to the efficiency of 98.4% irradiation uniformity. The performance of the solar thermoelectric system can be further improved by using a double-layer TE structure. At a concentration ratio of only 12.4, the double-layer system connected in series achieved a maximum efficiency of 2.06%, which is 0.55% higher than the single-layer system. The importance of optimizing irradiation uniformity to improve system performance is experimentally revealed. These results are important for clarifying the operating principle of the solar thermoelectric system under non-uniform irradiation and can guide the subsequent design of high-efficiency solar thermoelectric systems.