Temperature Increment Research Articles

Performance evaluation of enhanced clustered latent heat system for air heater using modified organic material

The present work evaluates a new model of clustered latent heat storage unit (LHSU) which specifically designed for air heater. The system involves multi-tank which is arranged in staggered configuration. The clustered system uses direct charge for heating the storage material and employs forced air convection for heat liberation. The maximum temperature increment for the heated air is more than 50 %, showing an effective function of the proposed model. This work also analyzes the role of storage material within the system. The stabilized storage material demonstrates a better performance in term of minimum heat loss on the charge stage. Also, it allows for an excellent charge behavior with average of 3.44 °C/min. The LHSU can be combined with an additional fin for accelerating the operation, making the system can be applied flexibly based on the requirement of the energy system. The operation curve is displayed as battery percentage to understand the characteristics of the system during energy interaction. In general, the addition of fin and modified storage material leads to significant improvement, offering the applicability of the proposed model in various technologies for air heater systems.

A model for root water uptake of alpine meadow on the Qinghai-Tibet Plateau considering soil temperature

Predicting root water uptake (RWU) of wide-distributed alpine meadow on the Qinghai-Tibet Plateau (QTP) is essential to precisely reveal the complex hydrothermal behaviors of alpine meadow soil under warming and humidifying climate. In this study, a model for RWU of alpine meadows on the QTP is proposed, which comprehensively considers the actual root characteristics of alpine meadow and the influence of soil temperature. In the proposed model, a root density function is newly derived to describe the root characteristics of alpine meadows, where root biomass (RB) is taken as root characteristics index. Meanwhile, a temperature-dependent reduction function is developed to reflect the impact of soil temperature on the RWU of alpine meadows. The proposed model for RWU is highly competent compared to the model for RWU not considering soil temperature. Furthermore, the proposed model for RWU is applied to explore the influence of RWU effect on the water movement of soil under different soil temperatures. Results indicate that the increment of soil temperature can lead to the exponentially increasing trend for the RWU rate of alpine meadows. Under the RWU effect, the alpine meadows with the thickness of 0.25 m have contributed to the moisture redistribution of soil layer within the range of 0.75 m. At the maximum soil temperature of 23 °C, the maximum RWU rate of 25.16 × 10−9 1/s leads to the maximum decline in volumetric water content of 6.31%. Higher soil temperature is beneficial to the stability of the shallow freeze-thaw slope covered by alpine meadows, which is the opposite of the influence of humidifying climate. It is helpful to disclose the failure mechanism of shallow freeze-thaw slopes of the QTP.

Characterizations and Energy Analysis of Hydroxyl Group Functionalized Graphene (Nanomaterial) Mixed with Paraffin Wax (Polymer Pcm) as Thermal Energy Storage Materials And Applications

This work comprised of Paraffin wax as phase change material mixed/doped with functionalized graphene (hydroxyl group) for countering the poor thermal conductivity of the pristine phase change material. Firstly, Experiments were conducted on Thermal energy storage system during charging (melting) of the doped PCM. The main outcomes of these experiments were that as the volume concentrations of doped PCM and flow rate of the heat transfer fluid (HTF) were increased the charging time decreases along with increments in PCM temperature and accumulated energies. In case of OH functionalized graphene mixed with paraffin wax the charging time decreases by 38.4% to 84.61% for the HTF flow rate 25 ml/s over pure paraffin wax. Secondly, the advanced functional materials i.e., Paraffin wax mixed with functionalized hydroxyl group graphene was characterized by FTIR, XRD, TGA, DSC and FESEM, . The latent heat of melting obtained was 179.36 J/g for 1% graphene doping by DSC.

Numerical Simulation of Effects of Catalyst Layer Parameters on Heat Transfer in Proton Exchange Membrane Fuel Cells

A non-isothermal, two-dimensional, two-phase fuel cell agglomerate model is used, and studies are done on how platinum loading and catalyst layer thickness affect heat transfer in fuel cells. Results indicate that as the cathode platinum content and catalyst layer (CL) thickness rise, the electrical property is improved. The maximum power density corresponding to the platinum loading of 0.40 mg/cm2 increases by 8.92% compared with 0.20 mg/cm2, and the maximum power density corresponding to the CL thickness of 17.5 µm increases by 4.63% compared with 10.0 µm. Temperature variation trends in CLs from entry to exit and inside the cell along the thickness direction do not change. Furthermore, with the CL thickness as well as platinum content increasing, the temperature increment inside cathode gas diffusion layer as well as CL is more obvious, and temperature distribution uniformity within the cell deteriorates. The impact of platinum loading on the temperature in the cell is more obvious than that of CL thickness. In the selection about platinum content and thickness of CL, temperature distribution uniformity and electrical property should be weighed.

Performance of capacitive deionizing membrane distillation (CDIMD) process for the organic sewage treatment and how operating parameters can affect it

To solve the fouling issue of traditional membrane distillation (MD) technique, a newly-designed hybrid purification system integrating capacitive deionization (CDI) with MD technology was established for the organic sewage treatment in this study, namely capacitive deionizing membrane distillation (CDIMD) technology. Complexes formation via cross-linking among protein, divalent cations, and polysaccharide, an archcriminal inducing MD fouling, was remarkably alleviated in the CDIMD system considering that negatively-charged organics were clearly divided away from those divalent cations in an electric field circumstance. The CDIMD performance was deeply explored in this study focusing on the impact mechanisms of core operational parameters. An appropriate increment of feed temperature (60–65 °C) and feed flow velocity (15.72–17.82 mm/s) contributed to the anti-fouling performance of CDIMD. Considering the side reactions at voltage >1.2 v, setting working voltage at around 1.2 v seemed to be optimal for CDIMD operation. With an overall consideration of pure water production and anti-fouling performance, a properly thicker CNTs layer (40–60 μm) efficiently enhanced the fouling mitigation of CDIMD. A frequent switching of electric field direction (9/1 min) facilitated the timely regeneration of electrode and composite membranes, accordingly promoting a reliable purification of organic wastewater by CDIMD technique.

Factors influencing the inactivation of Bacillus subtilis by epigallocatechin gallate (EGCG)

ABSTRACT Epigallocatechin gallate (EGCG) is an exceptional plant polyphenol for drinking water disinfection, due to its lasting antibacterial capabilities and broad spectrum of health benefits. Nevertheless, its effectiveness and the underlying mechanisms against chlorine-resistant bacteria, such as Bacillus subtilis, have not been thoroughly explored under various water conditions. The study at hand probed the inactivation rates of EGCG on B. subtilis was subjected to different concentrations, contact times, acidic or basic environments, and temperatures; biological mechanisms were examined by analyzing alkaline phosphatase, proteins, glucose, ATP, and redox biomolecules. Results indicated a positive correlation between EGCG concentration and the inactivation rate of B. subtilis, with the rate notably rising at EGCG levels below 800 mg/l and under acidic pH. The inactivation efficiency increased with temperature increments from 25 to 45 °C. Moreover, EGCG exerted a detrimental impact on the structural integrity, energy metabolism, and the antioxidant defense system of B. subtilis showed a dose-dependent antimicrobial activity against Escherichia coli. Consequently, this study provides a strong foundation for evaluating EGCG's efficacy against chlorine-resistant bacteria, promoting its theoretical application for drinking water treatment and guiding methodological advancements for broader applications.

Alternative green application areas for olive pomace catalytic pyrolysis biochar obtained via marble sludge catalyst

Evaluating industrial wastes in the system with minimum preprocessing and generation economically valuable products from them have critical importance. In this regard, especially cheap, wieldy, and readily available catalysts have been researched to increase variety of useful products in pyrolysis systems, to reduce process time, and to increase quality and diversity of products. Therefore, in this study, marble sludge (named K1) was evaluated as catalyst at different dosages (10%, 20%, 30%, 50%) and pyrolysis temperatures (300, 500, 700 °C) in olive pomace (OP) pyrolysis and; the potential green applications of produced new biochars at new usage areas with different purposes based on characteristics were investigated. ANOVA test results showed that temperature and catalysts ratio had significant effect on pyrolysis product yields since significance value for K1 and temperature was lower than 0.05 for pyrolysis products. OP-K1 biochars had alkaline properties and high earth metal quantities. Moreover, increment in K1 ratio and temperature resulted in decrement of the biochar surface acidity. Therefore, it can be indicated that these biochars can have a potential usage for anaerobic digestion processes, lithium-ion batteries, and direct carbon solid oxide fuel cell (DC-SOFC) but further electrochemical property test should be performed. Moreover, produced biochars can be alternative fuels in some processes instead of coal since they have low S content and high heat values. Consequently, it is foreseen that produced biochars will have an important place in the development of potential usage areas with a new and environmentally friendly approach in different areas apart from the conventional uses of catalytic pyrolysis chars.Graphical abstract

Statistical-based spatial analysis on urban water management under changing environments: a case study of Hawassa, Ethiopia

Hawassa characterizes a typical developing city in Ethiopia, owning to rapid urban growth and demographic trends. The combined effect of climate change and urban expansion is increasing the challenge to the environment and the services it provides. Relating changing environments with urban water management (UWM) is required to build resilience in the urban environment. This research analyzed local climate change and urban growth and linked it to UWM. The historical period 1990–2021 of daily rainfall, temperature variables, four satellite imageries, and DEM were analyzed. Changes in rainfall (annual and daily maximum) and temperature (maximum and minimum) trends are detected and projected to 2051 using a statistical-based model. With geospatial techniques sub-watersheds are delineated, and the urban cover change is quantified. The trend detection result implies an upward trend of annual and daily maximum rainfalls however a significance is insufficient (p > 0.05) to associate it with climate change during the study period. Maximum and minimum temperatures change indicate a positive and significant trend. The forecasting result suggests an increment of both temperatures (0.5 °C–1.5 °C) to the projected period compared to historical scenario. The land cover analysis results show the built-up area changed from 11.6 km2 (7.2%) to 42.5 km2 (26.5%) during the historical period, where the rate varies spatially. The surface runoff increased by 30.7% in the urban watersheds. With a growth rate of 8.9% built-up, the urban area will cover 73.6 km2 (45.9%) for the predicted period. The research finding justifies the potential to reorganize the relationship between the spatial effect of climate change and urban growth on UWM. Considering distinct characteristics of urban watershed, exposure to flooding risk, access to water demand and resilient to climate change have spatial variation. Thus, a local-specific planning approach will support effective UWM and climate adaptation for sustainable city development.

Study of the effects of heating on the physical, optical, and electrical properties of NiO thin films synthesized using a low-cost sol-gel method

Developments in low-cost techniques for growing high-quality nickel oxide thin films (NiOTFs) are critical enablers for the fabrication of NiO-based devices, particularly solar cells, light-emitting diodes, lasers, and many other applications. In this study, it has been demonstrated that the optical, electrical, and structural characteristics of NiOTFs coated on glass substrate employing a low-cost solution method are strongly influenced by post-thermal annealing treatments in ambient air. A comprehensive study was carried out on the characteristics of the deposited NiOTFs. X-ray diffraction (XRD) measurements indicate the enhancement of the crystal quality of films after annealing. There is a noticeable change and improvement in coated NiOTFs with heat treatment at 300 and 600 ℃ due to clear shifts in density. During the heating temperature increment, the energy of the band gap was shifted from 3.63 to 3.44 eV, and the electrical resistance of the NiOTFs varied from 1020 to 700 Ω-cm. Furthermore, the results indicate that the low-cost sol-gel (SG) deposition technique has a greater potential for producing high-quality p-type NiOTFs with minimal defects for electronic device applications.

Heat flow density measurement during non-destructive testing

The object of the study is the development of a device capable of accurately and reliably measuring heat flux density in various environments. The development of a heat flux density meter designed for non-destructive analysis of thermal processes in various fields of application is presented. The developed device is intended for evaluating the thermal insulation condition of underground pipelines. The functionality of the heat flow device relies on comparing standard temperature values with experimental ones measured on the soil surface. To ensure accurate and reliable measurement of heat flux density, the basis is a thermoelectric battery converter, which uses the auxiliary wall method. The heat flow density measuring device is constructed in the shape of a restricted cylinder, with one base serving as the working surface, while the second base establishes thermal contact with the body at ambient temperature. Embedded heaters enable the generation of heat flow through the thermoelectric sensor in directions perpendicular to its base. For calibrating the heat flux device, experiments were conducted using a standard copper-constantan calibration table. Temperature increments were determined from thermo electromotive force, and tests were performed on an existing heating network. The conducted measurements validate the fundamental feasibility of employing the proposed device for implementing the non-destructive thermal testing method on underground heating mains. The results of the experiment can be used not only for research, but also for monitoring and regulating processes in various fields of science and technology. The developed heat flux meter promises a significant contribution to the development of modern methods for analyzing thermal processes. The dimensions of the thermoelectric battery converter are also determined and the coefficient (kq) should be in the range from 4.0 to 12.0 W/(m2⋅mV), and the electrical resistance should be in the range of 12–20 kOhm

Microstructure and finite element analysis of Mo2C-diamond/Cu composites by spark plasma sintering

Abstract Mo2C layer was generated on the diamond surface via vacuum micro-evaporating, which was used as the reinforcement particles to fabricate diamond/Cu composites by spark plasma sintering (SPS). The effect of evaporation parameters on the forming of Mo2C, and the holding time on diamond/Cu composites fabrication is studied. Combined with the experiment and finite element analysis (FEA), the holding time on diamond/Cu composites influence on the thermal conductivity (TC) of composites is further discussed. The results show that the Mo2C area on the diamond surface would gradually enlarge and cover the diamond surface evenly with the increment in evaporation time and temperature, better vacuum micro-evaporating parameters were given as 1,000°C for 60 min. The fractures in the diamond/Cu composites are mainly ductile fractures on copper and diamond falling out from the Mo2C interface. It was found that sintering time would significantly influence the dissipation property of diamond/Cu composites. A comprehensive parameter for SPS was obtained at 900°C, 80 MPa for 10 min, the relative density (RD) and TC of the composites obtained under the parameter were 96.13% and 511 W/(m K). A longer sintering time would damage the Mo2C interlayer and further decrease the bonding between copper matrix and diamond particles, which would lower the RD and TC of composites. It can be obtained from the comparison of simulation results and experimental results that the FEA result is closer to the experimental results due to the gaps with low heat conduction, and the air in the gaps is added in the simulation process.

Development and physiochemical assessment of graphene-bioactive glass-P(3HB-co-4HB) composite scaffold as prospect biomaterial for wound healing

The clinical management of wounds presents a considerable challenge because dressing selection must prioritise the provision of appropriate barrier and the healing properties, consider patient’s compliance factors such as comfort, functionality and practicality. This study primarily aimed to develop a composite scaffold patch for potential application in wound healing. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] is a biopolymer that originated from bacteria. It is well-recognised owing to its distinctive mechanical and physical characteristics suitable for biomedical applications. Graphene (G) and bioactive glass (BG) are biocompatible towards humans, and enhanced properties are achievable by adding biopolymer. In this study, composite scaffolds were developed by combining P(3HB-co-4HB) at a distinct proportion of 4HB monomer reinforced with G (3.0 wt.%) and BG (2.5 wt.%) by using solvent casting, resulting in two types of composite scaffolds: P(3HB-co-25%4HB)/G/BG and P(3HB-co-37%4HB)/G/BG. A successful composite scaffold as a unified structure was achieved based on chemical assessments of organic and inorganic elements within the composites. The pure polymer displayed a smooth surface, and the BG and G addition into the composite scaffolds increased surface roughness, forming irregular pores and protuberances. The wettability and hydrophilicity of the composites significantly improved up to 40% in terms of water uptake. An increment in crystallisation temperature diminished the flexibility of the composite’s scaffolds. Evaluation of Presto Blue biocompatibility demonstrated nontoxic behaviour with a dosage of less than 25.00 mg ml−1 of composite scaffold-conditioned media. The L929 fibroblast cells displayed excellent adhesion to both types of composite scaffolds, as evidenced by the increased percentage of cell viability observed throughout 14 d of exposure. These findings demonstrate the importance of optimising each component within the composite scaffolds and their interrelation, paving the way for excellent material properties and enhancing the potential for wound healing applications.

Assessing water position through distributed temperature sensing using Rayleigh-based optical frequency-domain reflectometry: a laboratory feasibility study

This study demonstrates the ability of the Rayleigh-based phase-noise compensated optical frequency-domain reflectometry (PNC-OFDR) sensing method to monitor the distributed temperature field with an ultra-short data acquisition period of 2 ms, a spatial resolution of 2 cm, and a temperature resolution of 0.1 °C. A heating cable (H-cable) was embedded within a cylindrical concrete mortar specimen and subjected to various heating powers. A sensing optical cable (T-cable) was placed adjacent to the heating cable to monitor the temperature distribution continuously. Two water-holding boxes were installed along the specimen at two positions to retain water. The results of the study indicated that the PNC-OFDR technique demonstrated a high sensitivity to even small temperature changes, enabling it to accurately pinpoint the locations of water at two distinct points. The research determined the minimal heating power required for successfully locating the water positions. The magnitude of the heating power exerted a significant impact on the temperature change. Three distinct phases of temperature increment were observed for a given heating period: rapid, fast, and gentle increase. The insights gained from this study have the potential to be applied in natural fields, allowing for the detection of groundwater and seepage phenomena in vulnerable slopes.

Influence of microstructure evolution and element segregation on high temperature tensile behaviors in GH4706 alloy

This work systematically investigated the influence of microstructure evolution and element segregation on tensile properties and fracture behaviors of GH4706 superalloy under different temperatures (25 °C, 400 °C, 500 °C, 600 °C and 650 °C). The advanced methods of TEM, AES and SIMS were conducted to characterize the variation of microstructure and element distribution. Experimental results showed that the yield and tensile strength of the test alloy decreased while the corresponding elongation increased as the increment of test temperature. The dominated fracture mode was intergranular brittle fracture at the temperature of 25 °C, gradually transforming to ductile dimple fracture as the temperature increased. This phenomenon was determined to be closely related to the increment of average grain size and size of γ'/γ″ coprecipitates as temperature rose. It was worth noticing that the elongation performed abnormally low (16.3%) at the temperature of 500 °C, exhibiting intermediate temperature brittleness (ITB) phenomenon. The SIMS analysis showed that the segregation of S towards grain boundary was the most obvious at the temperature of 500 °C, which was considered as the main factor leading to ITB. In addition, the coarsening of carbides at grain boundaries and local strain non-uniformity caused by dislocations could also resulted in ITB. The main reason for maintaining good strength and plasticity at the temperature of 650 °C was contributed to the softening of γ' phases by repeated cutting of dislocations and deformation twins, reducing the hindrance to the movement of dislocations. Moreover, composite strengthening effect of P and B could improve bonding strength, stabilize grain boundaries, and effectively suppress the initiation of intergranular cracks.

Amplified linear and nonlinear chiral sensing assisted by anapole modes in hybrid metasurfaces

The interaction between chiral molecules and circularly polarized light is largely influenced by the local optical chirality density. This interaction prompts substantial demand of the design of nanophotonic platforms capable of enhancing such effects across large and accessible volumes. Such a magnification requires nanostructures that provide strong electric and magnetic field enhancements while preserving the phase relation of circular light. Dielectric nanostructures, particularly those able to support resonances, are ideal candidates for this task due to their capacity for high electric and magnetic field enhancements. On the other hand, efficient third harmonic generation requires strong electric field resonances within dielectric materials, a feature often boosted by incorporating plasmonic materials into hybrid systems. In this work, we numerically propose a coupled silicon disk-gold ring system that can exploit the anapole-induced field confinement to provide a broadband magnified circular dichroism under realistic conditions, reaching values up to a 230-fold enhancement. We also demonstrate that this structure can be employed as an efficient third harmonic generator, which, when integrated with chiral media, enables an 800-fold enhancement in circular dichroism. Furthermore, we show that pulsed illumination at intensities up to 10 GW/cm2 does not induce temperature increments that could potentially damage the samples. These findings suggest that this system can be a promising and versatile approach toward ultrasensitive chiral sensing.

Estimation of preheating time for building intermittent heating subject to changes in outdoor temperature and solar radiation

Intermittent heating is to maintain indoor temperature of buildings in winter within a comfort range only during occupancy periods. Buildings have thermal inertia causing slow increments of indoor temperature, so that a preheating time is required to start heating in advance of occupancy periods. In this paper, a new method is presented to determine preheating time for building intermittent heating subject to changes in outdoor temperature and solar radiation. First, a dynamic model is developed to describe relations between indoor temperature as an output and three inputs including the heating medium temperature, outdoor temperature, and solar radiation. The dynamic model with modeling uncertainties is identified from input-output historical data. Second, the identified model is used to predict indoor temperature under future data of three inputs, and optimal preheating times are determined with a certain probability to ensure successful preheating. The experimental examples show that the dynamic model accurately describes the indoor temperature changes, and the preheating times from the proposed method are more accurate than four existing methods.

Exploring and validating heating dynamics in a radio-frequency electromagnetic field-based resonant chamber for mouse hyperthermia research

ABSTRACT Mild whole-body hyperthermia has been shown to have anti-tumor effects through an immune-modulating mechanism. Before it is widely applied in the clinic, tremendous mechanistic research in animals is necessary to adhere to evidence-based principles. The radio frequency electromagnetic field (RF-EMF) based heating facility could be a good choice for hyperthermia treatment, but the heating characteristics of a facility, including structure design, electromagnetic and thermal dosimetry, and the biologic effects of hyperthermia, need to be well elucidated. Here, we reported the heating characteristic study on a resonant chamber (RC) excited by a 1800 MHz solid source. The EMF in the RC was stirred by 24 static reflectors, which resulted in the standard deviation of electric field intensity being below 3 dB in the EM homogeneity evaluation. For the exposure scenario, six free-moving mice were loaded into separate cases and exposed simultaneously in the RC. The EMF energy absorption and distribution in exposed mice were calculated with the 12-plane-waves method of numerical simulation. Different levels of core body temperature increment in exposed mice were achieved through regulation of the source output power. Overexpression of heat shock proteins (HSPs) was detected in the liver, lung and muscle, but not in the brain of the exposed mice. The levels of representative inflammatory cytokines in the serum, TNF-α and IL-10 increased post RC exposure. Based on the heating characteristic study and validation, the applied RC would be a qualified heating system for mild whole-body hyperthermia effect research in mice.

Numerical study of electroconductive non-Newtonian hybrid nanofluid flow from a stretching rotating disk with a Cattaneo–Christov heat flux model

Motivated by emerging technologies in smart functional nanopolymeric coating systems in pharmaceutical and robotics applications, the convective heat transfer characteristics in swirl coating with a magnetic hybrid power-law rheological nanofluid polymer on a radially stretching rotating disk are examined theoretically. An axial magnetic field is imposed. Copper (Cu) and aluminium alloy (AA7075) nanoparticles with sodium alginate (C6H9NaO7) as a base fluid are considered, and a hybrid volume fraction model is deployed. A non-Fourier (Cattaneo–Christov) heat flux model is deployed to inspire thermal relaxation impacts absent in the classical Fourier heat conduction formulation. Through similarity proxies and the Von Karman transformations, the partial derivative systems of equations with associated boundary constraints are reduced to a system of derivative boundary value problems, which is solved numerically via the weighted residual method with an integral Galerkin scheme, executed in the MAPLE symbolic software. Validation with special cases from articles is captured. The computations revealed that radial, tangential and axial velocity are depleted, whereas temperature is enhanced with increasing magnetic parameter ( M). High thermal transfers are obtained for the hybrid nanofluid relative to the AA7075 alloy nanofluid. A strong increment in temperature is also produced with a greater thermal relaxation effect.

Energy storage and dielectric properties in PbZrO3/PbZrTiO3 antiferroelectric/ferroelectric bilayer bulk structure using Landau theory

Employing Landau theory and the Landau–Khalatnikov (L–K) equation of motion, we investigate the phase transitions in individual layers of antiferroelectric lead zirconate (PbZrO3), ferroelectric lead zirconate titanate (PbZrTiO3), and an antiferroelectric/ferroelectric PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer bulk structure. We examine the dielectric hysteresis loop behavior of the three systems, with a specific focus on the PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer under different stabilities of the PbZrO3 layer. In addition, we explore cases where the coercive field of the bilayer structure is lower than that of the PbZrTiO3 individual layer. The recoverable electric energy for the PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer increases significantly to 118 J/cm3 at an applied field of 7.5 × 108 V/m at 20 °C. In comparison, the PbZr(0.21)Ti(0.79)O3 layer reaches 71.8 J/cm3 under the same field and temperature conditions. This is much higher than those predicted experimentally by previous studies on thin film single and bilayer structures (15.6 and 28.2 J/Cm3 respectively), indicating that the antiferroelectric/ferroelectric PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer bulk structure could be used to target specific large-scale, long-term energy storage applications. Upon increasing the value of the coupling coefficient, the transition temperatures of the PbZrO3 layer and the PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer are increased up to the transition temperature of the PbZr(0.21)Ti(0.79)O3 individual layer (450 °C). This increment in the transition temperature in the bilayer system contributes to its stability in storing energy at higher temperatures. Furthermore, the recoverable energy density of the PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer increases further with temperature from 20 to 440 °C correlated with the rise in the difference between the spontaneous and the remanent polarizations (Ps − Pr). The significant stored energy observed over a wide temperature range highlights the promise of this bilayer structure for creating high-power capacitors where stability at different temperatures is crucial and possesses greater energy storage capacity.

Diminish charge loss by mica incorporation into nylon nanofibers for performance enhancement of triboelectric nanogenerators operating in harsh ambient

The triboelectric nanogenerator (TENG) is a fascinating energy-harvesting device that utilizes the triboelectric effect caused by contact electrification and electrostatic induction. Nylon 66 is used widely in TENG applications because it is a representative tribo-positive polymer with excellent biocompatibility. On the other hand, the generated charges are vulnerable to discharge due to moisture in the air, which impedes the TENG performance in harsh environments. Moreover, the dielectric loss, which generates heat by consuming the considerable electric charge in triboelectric materials, significantly degrades the TENG performances. This study fabricated the composite nanofiber (NF) structure of nylon 66 and mica, which has excellent electrical insulation, low dielectric loss, high thermal conductivity, and enhanced tribo-positive properties, to circumvent these problems. Embedding the mica into the nylon NFs enhanced the TENG performance and prevented performance degradation even in harsh environments at a relative humidity of 70%. Furthermore, after 100,000 cycles of friction, the nylon/mica composite NFs showed smaller temperature increments than the pristine nylon NF because of the low dielectric loss and efficient heat dissipation of the mica. The nylon/mica composite NFs were applied to a sustainable and wearable power generator operating in a humid and hot environment by attaching the device to the forearm and soles of the feet. The generators were efficient enough to turn on 80 light-emitting diodes.