High Thermal Energy Storage Capacity Research Articles

Production and assessment of UV-cured resin coated stearyl alcohol/expanded graphite as novel shape-stable composite phase change material for thermal energy storage

Expanded graphite-phase change materials (PCM) structures are reinforced to polymers with various methods to fabricate advanced thermal energy storage materials. However, these methods still suffer from processing time and product efficiency challenges. In this study, the UV-curing method was used to produce shape-stable EG-PCM-reinforced resin composites with fast curing and low process temperature of the resin. The composite material, comprising UV-curable resin (30 %), stearyl alcohol (65 %), and Expanded graphite (5 %), was synthesized. This synthesis aimed to address the limitations of traditional PCMs, such as low thermal conductivity and leakage. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the materials' phase change behavior and thermal stability. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses were conducted to elucidate the microstructure and crystallinity of composite materials. The composites, exhibiting near-perfect impermeability with leakage as minimal as 0.89 %, not only enable the attainment of cooler environments by 2–3 °C under hot air conditions but also demonstrate exceptional thermal stability up to 207 °C, as evidenced by TGA results. Additionally, they offer a remarkable melting enthalpy value of 153.1 J/g. These composites, with their shape-retention ability during phase transitions and high thermal energy storage capacity, are a versatile and efficient option for sustainable energy management. This research contributes to the development of innovative materials for renewable energy integration and reducing carbon emissions.

Polypyrrole-modified flax fiber sponge impregnated with fatty acids as bio-based form-stable phase change materials for enhanced thermal energy storage and conversion

In this study, we integrated organic phase change materials, decanoic acid (DA) and palmitic acid (PA), into bio-based samples made from sodium alginate (SA) and flax fiber (FF). We also synthesized conductive polypyrrole (PPy) coating through in situ polymerization to create two thermal energy storage and conversion systems with distinct phase change temperatures (32 °C and 63 °C). The PPy coating exhibited uniform polymerization, resulting in electrical conductivity (1.52 ± 0.07 S/m) and thermal conductivity (0.453 ± 0.02 W/mK). The conductive sponge, similar to the plain sponge, had a porous microstructure (85 % porosity) that allowed successful impregnation of 60 % and 74 % of DA and PA, resulting in outstanding energy storage and conversion properties. Specifically, the conductive sponges with DA and PA achieved phase change enthalpies of 100.98 J/g and 154.52 J/g, respectively. DA/PPy@Sponge demonstrated exceptional durability after thermal cycling tests. Furthermore, the conductive sample efficiently converted electrical energy into thermal energy along the conductive path, making it suitable for storing generated heat as both sensible and latent heat, as well as capturing and storing solar energy. Overall, the developed conductive phase change materials offer shape stabilization, high thermal energy storage capacity, and efficient electric/photo-to-thermal conversion properties. These attributes make them promising candidates for diverse applications in energy harvesting, storage, and management in electronics, buildings, transportation, and other relevant fields.

Bio-based sunflower carbon/polyethylene glycol shape-stabilized phase change materials for thermal energy storage.

The exploitation of shape-stabilized phase change materials with high thermal conductivity and energy storage capacity is an effective strategy for improving energy efficiency. In this work, sunflower stem carbon/polyethylene glycol (SS-PEG) and sunflower receptacle carbon/polyethylene glycol (SR-PEG) shape-stabilized phase change materials, utilizing sunflower stem and receptacle biomass carbon with high specific surface area and pore volume obtained by carbonization as frameworks and polyethylene glycol as an energy storage material, were prepared by the vacuum impregnation method. The ability to load polyethylene glycol into the pore structure of carbon materials in different sunflower parts was mainly investigated, and the micro-morphology, compositional structure and thermal properties were characterized and analyzed using SEM, IR spectroscopy, XRD, DSC and TG techniques. The results showed that the carbonized sunflower stems maintained the sieve pore structure, and the carbonized sunflower receptacle was a macroporous structure containing a large number of three-dimensional interconnections. At the same time, the interaction between polyethylene glycol and each carbon material occurred through physisorption. The melting enthalpies of SS-PEG and SR-PEG shape-stabilized phase change materials were 153.4 J g-1 and 171.5 J g-1, respectively, and the loading rates reached 81.9% and 91.5%, with initial thermal decomposition temperatures (T 5%) of 344 °C and 368 °C.

Coupling effect of radiative cooling and phase change material on building wall thermal performance

Phase change material (PCM) featured with high latent heat thermal energy storage capacity and isothermal phase transition is employed into building walls decorated with radiative cooling (RC) coating, in order to modify the cooling effect on building thermal performance. Numerical analysis indicates that the RC coating causes exterior temperature of P-RC walls lower than ambient temperature, achieving maximum exterior temperature drop of 13.63 °C. Thermal buffer effect of PCM enables to shave the temperature peak and shift the temperature valley, inducing exterior temperature of the P-RC wall to fluctuate slightly in comparison to the RC wall. Interior temperature of the P-RC wall is found to approach to target temperature tightly. PCM located closer to the outside completes phase transition more rapidly, which is beneficial to levelling radiative cooling of RC coating. Exterior temperature of P-RC walls increases with augment of solar radiation intensity, ambient temperature and indoor temperature. Augment of PCM thickness, ambient temperature or indoor temperature is conducive to interior temperature. Latent heat thermal energy storage of PCM enlarges effective thermal capacity of walls, which is favorable to maintain interior temperature within target temperature. In conclusion, studied results highlight that radiation cooling can be improved by PCM, with substantial benefits to develop passive cooling available to building energy conservation.

Polyethylene Glycol Confined in SiO2-Modified Expanded Graphite as Novel Form-Stable Phase Change Materials for Thermal Energy Storage.

Form-stable phase change materials (FSPCMs) composed of poly(ethylene glycol) (PEG) encapsulated in SiO2-modified expanded graphite (EG@SiO2) were prepared and investigated for thermal energy storage behaviors. The modification of SiO2 on EG was done using a simple sol-gel method, and then the resulting EG@SiO2 was introduced to confine PEG at varying content (60-90 wt %). Surface properties (including microstructure, morphology, and functional groups), PEG adsorptivity, leakage-proof ability, and thermal energy storage of the prepared materials were thoroughly characterized and discussed. The EG@SiO2 with 15 wt % SiO2 outstandingly adsorbed PEG as compared to the pristine EG, showing up >80 wt % of PEG. As a result, PEG was well stabilized in EG@SiO2 porous network without leakage, owing to capillary force, surface tension, and hydrogen bonding interactions. The optimal 80 wt % PEG/EG@SiO2 composite possessed high crystallinity (93.5%), high thermal energy storage capacity (132.5 J/g), and excellent thermal conductivity (4.086 W/m·K). In addition, it exhibited good cycling durability after 500 repeated melting/crystallization cycles. The high thermal efficacy and inexpensiveness would make the PEG/EG@SiO2 FSPCMs suitable for scale-up applications in thermal energy storage.

Microencapsulation study of bioderived phase change material beeswax with ethyl cellulose shell for thermal energy storage applications

ABSTRACT The commercial shape-stabilized phase change material (PCM) products are obtained from synthetic raw materials. These materials are produced from carbon-intensive petroleum-refining processes. The carbon footprint can be minimized by using biobased products. Beeswax is a naturally available PCM with high phase transition enthalpy comparable to synthetic PCMs. In the previous literature studies, beeswax was shape-stabilized with synthetic materials. In the present study, beeswax was shape-stabilized with biopolymer ethyl cellulose by emulsion solvent evaporation method. The study aims to determine optimum microencapsulation process parameter levels for synthesizing microcapsules with high thermal energy storage (TES) capacity. The optimized process parameters for formulating microcapsules were 60:40 core/shell ratio, 2% PVA concentration, ethyl acetate solvent, and 40°C evaporation temperature. The microcapsules prepared with optimized process parameters were characterized using differential scanning calorimeter (DSC), T-history analysis, Fourier transform infrared (FTIR) spectroscope, and scanning electron microscope (SEM). FTIR and SEM analysis confirmed ethyl cellulose shell formation over the beeswax core. The optimized MPCM formulation possesses 115.8 J/g melting enthalpy with peak phase transition temperature of 58.2°C and thermal conductivity of 0.219 W/mK. The porous structure of the shell reduced melting enthalpy of optimized MPCM formulation to 84.6 J/g after 50 thermal cycles. The synthesized microcapsules comprise sustainable materials and have high TES capacity. The fabricated microcapsules can be used as TES additive in composite and coating formulations in food packaging.

The sono-PCM reactors: A new approach for recovering the heat dissipated from ultrasonic reactors using a phase change material

To keep sonochemical reactors at a constant temperature, cryothermostat systems (equipped with a pump, cooling fluids and tubing) are commonly used. The cryothermostat serves a dual purpose, supplying both heating and cooling as needed to keep the temperature stable. However, this device is an energy consumer, especially when the sonochemical reaction is carried out over an extended period of time (hours to days). As a result, alternative systems are required to reduce the operating cost of sonosystems. The present work introduces a new approach of incorporating phase change materials (PCMs) for the recovery and storage of heat dissipated from ultrasonic reactors (i.e. the sono-PCM reactor approach). The purpose of the project is to go as far as replacing the circulating fluid-based cooling system with a small PCM unit capable of absorbing the generated heat flux and storing it in the form of latent heat (with phase change). The analysis was made on sonicated water (300 mL) in a standing wave ultrasonic reactor operating at 300 kHz, where the dissipated heat flux was measured calorimetrically. After that, using a computational fluid dynamics (CFD) model (implemented in ANSYS Fluent® software), the energetic performance of the PCM unit was assessed by tracking the system (i.e. the sono-PCM reactor) response (i.e. average and spatial evolutions of temperature, enthalpy, total energy, velocity and PCM-melting kinetics) to the imposed acoustic energy. Paraffin RT31 was selected as PCM because of its suitable characteristics such as low melting point (27–31 °C) and high thermal energy storage capacity (165 kJ kg−1). Despite the relatively low thermal conductivity of the used PCM (0.2 W m− 1 °C − 1), promising results have been obtained in terms of thermal energy management and storage using a phase change material (PCM) instead of a water-cooling system.

Thermal properties of phase change materials ionic liquid/fatty acids for thermal energy storage applications

Researchers have developed advanced energy storage techniques in response to the depletion of energy resources and the escalation of environmental problems caused by increasing population and technological advancements. One of the most promising methods to overcome such issues is the latent heat thermal energy storage (TES) method, which employs phase change materials (PCMs). TES using PCMs are an important category of novel materials that significantly contribute to the efficient use and conservation of solar energy and wasted heat. This work presents a new family of PCMs based on ionic liquid (IL) tris(2-hydroxyethylammonium) formate and fatty acids for the first time that operate in the temperature range of 50–150 °C and offer a safe and inexpensive capacity. Good chemical and thermal stability, low flammability, and low volatility along with the potential to tune chemical and phase properties provide an inherent “green” property for ILs that is well suited to PCMs. Using PCM3, tris(2-hydroxyethylammonium) formate/stearic acid, we demonstrate effective latent heat 246 J·g−1. The results of differential scanning calorimetry analysis show that the PCM2 tris(2-hydroxyethylammonium) formate/palmitic acid has a higher heat capacity 8.194 J·g−1·K−1 at the melting point than the other two PCMs due to its small alkyl chain. Thermal stability analyses show the maximum stability (98 %) for PCM3. Additionally, based on the structure of these PCMs, this study explores the molecular basis for the high thermal energy storage capacity of these materials and highlights the significance of hydrogen bonds in PCM performance. Using simple, cost-effective materials, this method gets around the complexity and expense of composite PCMs. We present design recommendations for implementing our approach in the management of thermal energy storage applications.

Unveiling sustainable nano-enabled phase change materials for high thermal stability and energy storage capacity

Thermal energy storage and conversion within phase change materials (PCMs) rely on the addition of supporting materials, such as nanomaterials, to improve leakage resistance and heat transfer properties. However, as the supporting fillers obtained from different sources and synthesis methods, the development of renewable and sustainable phase-change composites has received increasing attention in recent years. Here, we develop a phase change composite and adopt Ashby material selection alongside life-cycle assessment to compare and demonstrate the sustainability of different nano-enabled PCMs. The report considers both the environmental impact, economic feasibility and functional performance, including thermal conductivity and energy storage density. The assessment shows that biochar, a biomass derived carbon at low pyrolysis temperature, supporting paraffin composites shows an encapsulation efficiency of >50 %, high shape stability/leakage-resistance capability, suitable cumulative energy demand (100–1000 MJ/kg), and the lowest price (43.00 $/kg with one volume concentration) and price-performance ratio (0.48 $/kJ) In addition, the phase change composite exhibited high chemical compatibility with paraffin, high leakage-resistance (above the pristine phase change temperature at 50 °C) and lowest thermal conductivity (<0.4 W m−1 K−1) compared with other carbon-based phase change composites, such as graphene and carbon nanotubes supported paraffin, which is desirable and demanding for practical integration in insulation and building thermal energy management applications and can be used as an alternative carbon-negative sustainable phase change composite to reduce dependence on mineral-based construction materials.

TiN doped Ni–Co bimetal organic framework based-composite phase change material with enhanced photothermal conversion performance

Shape stability and excellent photothermal conversion performance are critical for composite PCMs in the field of solar energy utilization. This study prepares a nickel and cobalt-based bimetal organic framework (Ni–Co-BTC) which is further employed as the supporting material for 1-octadecanol (OD). The flower-like Ni–Co-BTC with an interconnected network exhibits large specific surface area, pore volume, and appropriate pore size distribution, which is conducive to the encapsulation of OD (up to 70 wt%). In addition, TiN nanoparticles are added to enhance the photothermal conversion performance of composite PCM. Therefore, the obtained OD/Ni–Co-BTC/TiN composite PCM exhibits considerable thermal energy storage capacity (145.8 J/g) and remarkable photothermal energy conversion efficiency (up to 97.75%). Furthermore, the composite PCM has outstanding thermal stability and reliability, and the phase change enthalpy is reduced by only 1.7% after 100 cycles. Accordingly, the composite PCM shows a promising application potential in solar energy harvesting, conversion and storage. • Bimetal organic framework is used as a novel supporting material for PCM. • The incorporation of Co 2+ improves the loading capacity of Ni–Co-BTC for octadecanol. • OD/NCB/TiN displays high thermal energy storage capacity and thermal reliability. • The photothermal conversion efficiency of OD/NCB/TiN is up to 97.75% by dopping TiN.

Shape-Stabilized Phase Change Materials of Stearic Acid Confined in Fumed Silica

Stearic acid (C18OOH) as a phase change material (PCM) possesses high potential for thermal energy storage applications. To prevent leakage of C18OOH in liquid state, a porous support is required to form shape-stabilized PCMs (SSPCMs) by impregnating C18OOH into the porous support. The SSPCMs were carefully investigated to demonstrate how the nanoconfinement in the porous support affects their thermal performance. In this work, a series of stearic acid/fumed silica (C18OOH/FS) SSPCMs with various C18OOH contents was fabricated, and their thermal characteristics were extensively examined. The FS provided an adequate inner void to confine up to 70 wt % C18OOH owing to its high porosity (88%). Meanwhile, C18OOH was well confined within the FS pore structure owing to hydrogen-bonding (H-bonding) interactions, surface tension, and capillary force. The SSPCM with an optimal content of 70 wt % C18OOH exhibited the melting and crystallization temperatures of 66.0 and 63.1 °C, respectively, which are slightly lower than those of pure C18OOH owing to the confinement effects. It also possessed good leakage resistance, a high crystallization fraction of 93.1%, and high thermal energy storage (TES) capacity of 146.3 J/g. Additionally, the composite exhibited excellent thermal cycling stability after 1000 melting/crystallization cycles. The thermal conductivity of the 70 wt % C18OOH/FS SSPCM (0.150 W/m·K) was lower than that of pure C18OOH (0.224 W/m·K), indicating that the SSPCM retards heat transfer during the heat charging and discharging processes. Generally, C18OOH/FS SSPCMs exhibit excellent TES capacity, high thermal cycling stability, and heat transfer retardation properties, with a facile preparation process at a low cost. Therefore, they are ready for industrial-scale applications in the fields of thermal insulation and thermal protection.

TaON doped metal-organic frameworks-based composite phase change materials with excellent photo-thermal conversion performance

It is of great significance for designing prospective composite phase change materials (PCMs) with high shape-stabilized property, good thermal conductivity and efficient energy storage and conversion capacity. This study successfully developed a novel composite PCMs that TaON nanoparticles doped polyethylene glycol/metal-organic frameworks (PEG/MOFs) using a convenient impregnation method. The inherent favorable thermal conductivity of HKUST-1 and the excellent visible light absorption ability of TaON endowed the composite PCMs with remarkably improved thermal conductivity (increased by 126.7% over pure PEG) and remarkable photo-thermal conversion ability (η: 89.9–94.6%). Furthermore, the composite PCMs exhibited not only high shape stability, high thermal energy storage capacity (148.1 J/g) but also outstanding thermal stability and reliability. Accordingly, this novel photothermal composite PCMs would be hopefully applied to efficient storage, management and utilization for solar energy.

Biomass-based phase change material gels demonstrating solar-thermal conversion and thermal energy storage for thermoelectric power generation and personal thermal management

The utilization of renewable biomass and the conversion of renewable energy are promising strategies for providing clean energy and meeting energy needs. In this work, a ternary phase change material gels (PCMGs) composed of octadecanol (OD), styrene-ethylene-butylene-styrene (SEBS) and hydroxylated carbon nanotubes (HCNTs) are proposed to realize the biomass utilization and solar energy harvesting. As a kind of biomass, OD possesses the characteristics of high phase change latent heat, low cost, renewability, environmental friendliness and biosafety. SEBS provides the crosslinked network to load the OD and introduce the free-standing feature. The HCNTs can realize the highly-efficient solar harvesting through the solar-thermal conversion. The Van der Waals force between SEBS and OD, the π-π interaction between SEBS and HCNTs and the hydrogen bond between OD and HCNTs enable the excellent form-stability. Taking advantages of the synergistic effect of the functional components, the proposed biomass-based PCMGs demonstrate high thermal energy storage capacity of 183.04 Jg−1, high solar absorbance of 95.68%, high cost-effectiveness of 3.92 × 10-5$J−1 and high cell viability of 117.9%. The biomass-based PCMGs are effectively applied in the thermoelectric power generation and personal thermal management. This work creates a state-of-the-art alternative for the next-generation solar-thermal materials devices.

Numerical investigation on melting behaviour of phase change materials/metal foam composites under hypergravity conditions

The integration of electronic devices in aerospace vehicles leads to a significant increase in the heat dissipation, which makes thermal management a severe challenge. Due to the high thermal energy storage capacity and the excellent thermal diffusivity, phase change materials (PCM)/metal foam composite is a potential thermal management material. In order to deepen the understanding of melting behaviour of PCM/metal foam under hypergravity, the numerical model considering natural convection, flow resistance of metal foam, and non-equilibrium heat transfer is proposed, and the effects of inclination angle, hypergravity value, metal foam porosity, and pore density on the melting are analyzed. It shows that the inclination angle has a great influence on the morphology of the melting interface, while has limited influence on the variation of PCM liquid fraction. As the inclination angle changes from 0° to 180°, the heated wall temperature first decreases, and then increases after reaching the lowest value at 45°, which is the optimal inclination angle. With the rise of hypergravity value, natural convection is enhanced, the heated wall temperature is reduced, while the hypergravity value has limited effect on the PCM liquid fraction. Furthermore, with the increase of metal foam porosity, natural convection is enhanced, while the heated wall temperature and the melting time become larger. When the porosity is larger than 0.95, the effect of metal foam on natural convection suppression is greater than that of heat conductivity enhancement, leading to that the performance of PCM/metal foam is worse than that of the pure PCM. Besides, with the decrease of pore density, natural convection is enhanced, the heated wall temperature becomes lower. Therefore, metal foam with lower pore density is preferred. This paper provides guidance to the optimal design of PCM-based heat sink for aerospace applications.

Characterization of Low-Cost Particulates Used as Energy Storage and Heat-Transfer Medium in Concentrated Solar Power Systems.

Utilizing solid particles as a heat-transfer medium in concentrated solar power applications has gained growing attention lately. Unlike molten salts, solid particles offer many benefits, which include: high operating temperatures (greater than 1000 °C), a lack of freezing issues and corrosivity, abundant availability, high thermal energy storage capacity, a low cost, and applicability in direct irradiation. Comprehensive knowledge of thermophysical and optical properties of solid particles is essential to ensure an effective harnessing of solar energy. The most important considerations when selecting solid particles include: thermophysical and optical properties, thermal resistance, crack resistance, satisfactory health and safety risks, availability, and low cost. It is also imperative to consider optical and thermophysical characteristics that might change from what they were “as received” after cyclic heating for a long period. Therefore, the knowledge of thermal performance of particulate materials becomes significant before using them as a heat-transfer medium. In this study, some particulate materials were chosen to study their feasibilities as heat-transfer and storage media for a particle-based central receiver tower system. These particulate materials included white sand, red sand, ilmenite, and Carbobead CP. The candidate particulate materials were heated at high temperatures for 6 h and then cooled to room temperature. After that, cyclic heating was performed on the particulate materials for 500 h at 1200 °C. The optical properties were represented by weighted solar absorptance, and the thermophysical properties of the particulates were measured “as received” and after cyclic heating (aging). EDX and XRD were conducted to quantify the chemical composition and interpret the changes in appearance associated with the particulate materials after cyclic heating. The results showed a considerable agglomeration in all particulates except for white sand in the 6 h heating test, and high agglomeration in the ilmenite. A slight decrease in the optical properties in the white sand and Carbobead CP was found after the aging test. The specific heat was decreased for red and white sand. The EDX and XRD results for white sand and Carbobead CP showed chemical stability, indicating high durability and reliability.

Nanofibers for Renewable Energy

Electrospinning is a straightforward technique for the fabrication of nanofibers with the potential for various applications. Thermal energy storage systems using electrospun nanofibers have gained researchers’ attention due to its desirable properties such as nanoscale diameter, large surface area, excellent thermal conductivity, and high loading and thermal energy storage capacity. The encapsulation of phase change materials (PCMs) in electrospun nanofibers for storing renewable thermal energy can be achieved by uniaxial electrospinning of a blend of PCM and polymer, coaxial electrospinning of a PCM core and a polymer sheath, or post-electrospinning absorption. The PCM content and thermal energy storage capacity of different PCM composite nanofibers are compared in this chapter. The drawbacks of traditional electrospinning PCM encapsulation techniques and benefits of post-electrospinning encapsulation methods are discussed.

Experimental evaluation of the cooling performance of radiant ceiling panels with thermal energy storage

Demand-side management (DSM) strategies in buildings generally rely on short-term heat storage in structural thermal mass. However, the thermal storage capacity is limited by the available thermal mass as buildings are increasingly built using lightweight technologies. In addition, the structural thermal mass generally has a low heat storage and release rate, limiting the ability to manage building thermal loads. To overcome these limitations, we propose an innovative, flexible cooling system that can be installed in office buildings to replace conventional all-air systems. The system utilizes the high thermal energy storage capacity of macro-encapsulated phase change materials (PCM) discreetly incorporated below the serpentine copper coil of standard radiant ceiling panels (RCP). A walk-in dual climate chamber was used to evaluate experimentally the ability of the RCP-PCM system to shift cooling loads to off-peak hours. In addition, the heat removal capacity rate and the resulting indoor thermal environment improvements are assessed. The measured passive cooling power ranged between 11 W/m2 and 31.4 W/m2, with an average of around 17.3 W/m2. Results indicate that the RCP-PCM system can shift the cooling loads to off-peak hours while maintaining acceptable thermal comfort conditions during work hours (8:00 to 18:00). During the testing period, the system was able to passively absorb heat gains between 180 and 230 Wh/m2 during the day and operate actively only at night during unoccupied periods. This load-shifting capability of the RCP-PCM system can be of great help in planning DSM strategies for increased penetration of renewable electricity in building cooling applications.

Thermo-regulating performance of concrete slab loaded with shape stabilized phase change material in tropical climate

The building overheating problem is one of the most important problems facing all over the world. Various methods like using highly thermal resistive building materials, composite building materials were used to reduce the heat gain of the buildings. One of the method which can be used in place of traditional methods is using building elements with high thermal energy storage capacity. The significance of this study is to improve the thermal energy storage capacity of the building element for improving indoor thermal performance of the building. In this study latent heat energy storage capacity of the concrete slab is enhanced by incorporating Shape Stabilized Phase Change Material (SS-PCM) in it. SS-PCM was prepared by incorporating eutectic PCM (Paraffin Wax 70% and Coconut Oil 30%) in highly porous material called zeolite. The zeolite powder successfully incorporate 30 wt% PCM without showing any leakage at elevated temperature. Morphology of the SS-PCM was evaluated through Scanning Electron Microscopy (SEM) images. The SS-PCM at 0 wt%, 10 wt%, 20 wt%, and 30 wt% was used to prepare composite concrete slab by replacing fine aggregates. Composite concrete slabs were tested for indoor thermal behavior in real outdoor testing of 72 h. Indoor thermal performance was evaluated on the basis of peak temperature reduction, thermal amplitude, time delay, and decrement factor. The 30% SS-PCM has a high latent heat capacity, which significantly improves thermal energy storage in buildings. Various parameters like peak temperature reduction, time lag, thermal amplitude and decrement factor were evaluated. Concrete slab integrated with 30% SS-PCM shows maximum peak percentage temperature reduction of 10.04 % and percentage reduction in thermal amplitude of 23.71 % in comparison to conventional concrete. Additionally, infrared thermography of all the concrete slabs at different time of the day was done.

Highly-Efficient Thermal Management of Electronic Devices Enabled by Boron Nitride Incorporated Phase Change Material Gels with Superior Form-Stability, Enhanced Thermal Conductivity and High Thermal Energy Storage Capacity

Highly-Efficient Thermal Management of Electronic Devices Enabled by Boron Nitride Incorporated Phase Change Material Gels with Superior Form-Stability, Enhanced Thermal Conductivity and High Thermal Energy Storage Capacity

Production and Characterization of Nanoencapsulated Phase Change Materials (PCMs) and Bicomponent PCM Nanofibers

In this study, n-dodecanol and 1-tetradecanol were nanoencapsulated by poly(methyl metharcylate-co-methacrylic acid) (p(MM-co-MA)) wall using emulsion polymerization method which was defined as one-stage (OS) or two-stage (TS). Nanocapsules were analyzed by Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA). According to the analyses results, typical core-shell structured, spherical shaped, uniform nano-sized particles having high thermal stability and energy storage capacity were fabricated successfully. Enthalpy values of the nanocapsules prepared by TS process were higher and reached up to 171 J/g. It was concluded that thermal degradation stability of the nanocapsules could be improved using TS emulsion polymerization method. Besides, in the study, the nanocapsules were incorporated in polyacrylonitrile nanofibers using co-axial electrospinning method and composite nanofibers having 19 j/g energy storage capacities were produced. The prepared core-sheath structured nanofibers surfaces were rough and coarse but diameter distribution was unimodal.