High Thermal Energy Storage Capacity Research Articles

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.

Porous biochar/heptadecane composite phase change material with leak-proof, high thermal energy storage capacity and enhanced thermal conductivity

Solid-liquid phase change materials (PCMs) have been preferred for solar passive thermal energy storage (TES) applications. However, low thermal conductivity and leakage issue of molten PCMs considerably restrain their TES potential. In this framework, n-Heptadecane (HD) as a solid-liquid PCM was incorporated with carbonized lemon peel (CLP) for development of a novel leak-proof composite PCM. Chemical compatibility between the constituents of the leak-proof composite PCM was examined by using FTIR spectroscopy and XRD diffraction analyses. The DSC results revealed that the developed leak-proof CLP/HD composite PCM had a melting temperature of 19.79 °C and LHS capacity of 141.8 J/g. The composite PCM exposed venerable thermal degradation stability after a 1000-cycling heating-cooling process. Thermal conductivity of the CLP/HD composite PCM (0.46 W/m.K at 10 °C) was measured as approximately 77% higher than that of pristine HD (0.26 W/m.K at 10 °C).

Branched alkylated polynorbornene and 3D flower-like MoS2 nanospheres reinforced phase change composites with high thermal energy storage capacity and photothermal conversion efficiency

Form-stable phase change materials (FSPCMs) have a great attraction for relieving the contradiction of energy consumption and environmental pollution. However, the practical effects of FSPCMs are severely compromised by their intrinsic drawbacks including liquid leakage, inferior cycling durability and lacking light to heat conversion ability, etc. In this paper, we have constructed a group of novel composite FSPCMs with high latent heat storage density, enhanced thermal stability and excellent cycling life, using 1-octadecanol (OCC) as the latent heat storage units and the branched alkylated polynorbornene as well as 3D flower-like MoS2 nanospheres as the supporting scaffolds for the composite FSPCMs. The branched alkylated polynorbornene enhances the toughness of the composites under the induced dipole force among their alkyl chains so that the liquid leakage during the phase transition can be minimized or completely circumvented. Furthermore, 3D flower-like MoS2 nanospheres, as a photothermic absorbent, impart the composite FSPCMs with enhanced light to thermal conversion efficiency (85.5%), promising for a potential application in conversion and storage of solar energy.

Synthesis and properties of thermally enhanced aerated geopolymer concrete using form-stable phase change composite

Aerated concrete is composed of a large number of air voids to make it lightweight and to improve the insulation capacity; however, it possesses low thermal energy storage capacity. This paper reports the synthesis and properties of phase change material (PCM) composite integrated aerated/foamed geopolymer concrete (GFC) for enhancing the thermal storage capacity. A paraffin/hydrophobic expanded perlite based form-stable PCM composite was incorporated into the aerated concrete, and the chemical compatibility, mechanical properties, and thermal performance were experimentally evaluated. The FT-IR and TGA tests have indicated that the PCM composite is chemically compatible and thermally stable with GFC. The thermal performance tests on GFC, studied by simulated test rooms, has revealed that the GFC containing PCM composite has very high thermal energy storage capacity. The incorporation of 15% and 30% of PCM composite has reduced the peak indoor temperature of the test room by 1.85 °C, 3.76 °C, respectively while enhancing the thermal storage capacity by 105% and 181%. Despite the reduction in mechanical properties of geopolymer concrete with PCM, the GFC containing PCM has shown enhanced mechanical properties. The air-void distribution had also been improved with the formation of uniform and fine air voids in PCM integrated GFC. The enhancement in mechanical properties and uniform distribution of fine air voids was attributed to PCM composite's lightweight properties. This has resulted in reduced foam content to meet density requirements, thus increasing the size of gel particulates surrounding the air voids.

Form-stable phase change materials based on polyolefin elastomer and octadecylamine-functionalized graphene for thermal energy storage

Latent heat storage using organic phase change materials (PCMs) have the potential to alleviate the contradiction between supply and demand in energy. However, the usage of PCMs is compromised by deficiencies including liquid leakage during liquidation and solidification, poor thermal conductivity and inferior thermal stability. Herein, we successfully fabricated a series of novel form-stable phase change materials (FSPCMs), using the polyolefin elastomer (POE) along with the octadecylamine-functionalized graphene (C18-rGO) acted as the supporting networks and paraffin as the thermal energy storage material. The octadecyl chain incorporated on the surface of graphene not only prevented from the graphene aggregation, but also endowed excellent structural stability to the composite FSPCMs. Meanwhile, the toughness of the composites was further improved with the addition of POE. Paraffin was tightly imprisoned in the frameworks formed by POE and the C18-rGO, resulting in no leakage even above their phase change temperature. As expected, the composite FSPCMs demonstrated reliable thermal stability and high thermal energy storage capacity. In particular, the composite FSPCMs was capable of absorbing or releasing stored thermal energy at a high rate, illustrating a great potential to be used as the effective thermal energy storage and thermal management systems.

Pyrazolium Phase-Change Materials for Solar-Thermal Energy Storage.

Thermal energy storage technology utilizing phase-change materials (PCMs) can be a promising solution for the intermittency of renewable energy sources. This work describes a novel family of PCMs based on the pyrazolium cation, that operate in the 100-200 °C temperature range, offering safe, inexpensive capacity and low supercooling. Thermal stability and extensive cycling tests of the most promising PCM candidate, pyrazolium mesylate (Tm =168±1 °C, ΔHf =160 J g-1 ±5 %, ΔHtotal v =495 MJ m-3 ±5 %) show potential for its use in thermal storage applications. Additionally, this work discusses the molecular origins of the high thermal energy storage capacity of these ionic materials based on their crystal structures, revealing the importance of hydrogen bonds in PCM performance.

Thermal energy storage characterization of cementitious composites made with recycled brick aggregates containing PCM

This paper reports the results of an experimental program on sustainable cementitious composites made with Recycled Brick Aggregates (RBAs) employed as carriers for Phase-Change Materials (PCMs). The PCM-RBAs were produced by following an advanced incorporation and immobilization technique, developed and patented at the Institut für Werkstoffe im Bauwesen – TU Darmstadt. Spherical mortar samples made of plain cement paste plus porous RBAs, filled with liquid paraffinic wax, were used for monitoring the thermal behavior of various combinations of PCM-RBAs. The experimental campaign also comprised mechanical tests aimed at observing the effect of PCM in the RBAs, on the resulting mortar strengths under both compression and bending. Promising results have been obtained for the RBA mortars, showing a high thermal energy storage capacity at an almost negligible and acceptable strength loss due to PCM addition.

Phase change material blind system for double skin façade integration: System development and thermal performance evaluation

Double skin facades (DSFs) are often applied as energy reducing elements in modern buildings, but do experience overheating problems in warm seasons which may contribute to increase in cooling loads. There are currently various thermal management devices being used in DSF but have limitations such as secondary thermal transmittance and low energy storage capacity. In this paper, a novel laminated composite phase change material (PCM) blind system with high thermal energy storage capacity has been developed and evaluated in a typical DSF building. The results showed that the integrated PCM blind system was able to keep the average air temperature in the DSF below 35 °C during the monitored period in summer and showed no significant increase as compared with the ambient temperature. The surface temperature of the inner skin of the DSF was also reduced up to about 2.9 °C as compared with the external skin surface temperature thus reducing heat transfer into the building. By using validated numerical models, the PCM blind was found to perform thermally better than a conventional aluminium blind. Finally, design and operational parameters of the PCM blind including the blind tilt angle and its position were optimised. Further comparative studies against other integrated DSF systems are however being encouraged to establish the full effectiveness of the developed PCM blind system.

Biodegradable Polymeric Solid Framework-Based Organic Phase-Change Materials for Thermal Energy Storage

Phase-change materials (PCMs) are utilized for thermal energy storage (TES) to bridge the gap between supply and demand of energy. Organic PCMs, similar to paraffins, fatty acids, and polyethylene glycol, are extensively explored, thanks to their high TES capacity (∼5–10 times more than the sensible heat storage of water/rock), wide temperature range (spanning from −5 °C to 190 °C), good thermal stability over heating–cooling cycles (∼100 cycles), etc. However, “leakage” of PCMs upon transformation from solid to liquid has limited their usage as TES materials; thus, PCMs are confined to a biopolymeric framework for circumventing seepages. However, extensive analysis has concluded that there is a deficiency in availability of consolidated data on biopolymeric-based framework for PCMs. Thus, this review covers various literatures on the application of assorted biopolymers as framework for PCM. Simultaneously, we have also discussed on importance of biopolymers for constructing a framework for PCMs. Finally,...

Natural microtubule encapsulated phase change material with high thermal energy storage capacity

A novel microtubule encapsulated phase change material (MTPCM) for thermal energy storage was successfully prepared by embedding lauric acid (LA) in kapok fiber (KF) microtubules. Using a facile vacuum impregnation method, the obtained MTPCM achieved an unprecedented high thermal energy storage capacity up to 87.5% that of pristine LA. This capacity is much higher than previously reported values which are generally ˂60%. The high encapsulation ratio and thermal energy storage capacity can be ascribed to the unique thin wall and large hollow structure of KF. Moreover, the LA was confined inside the KF hollow fibers, leaving the interfiber space and surface free of LA. The MTPCM exhibited robust cycling stability and reusability without significant thermal storage capacity deterioration or phase change temperature variation after 2000 continuous heating/cooling cycles. In addition, the MTPCM showed enhanced thermoregulatory capacity compared with that of KF. Therefore, considering the nature microtubule is green, renewable, low cost, hollow structure with giant adsorption capacity, and the easily prepared MTPCM exhibits suitable phase change temperature, high latent heat, as well as excellent thermal reliability and thermoregulating capacity, the nature microtubule based MTPCM will have great potential from the viewpoint of renewable and sustainable development.

Thermal Energy Storage P(BeA-co-MMA) Microcapsules with Excellent Thermal Stability

Latent heat storage systems are a highly efficient and environmentally friendly way to use residual heat and store renewable energy. Phase change materials, which can absorb or release the enthalpy of phase changes in certain temperature ranges, are considered one of the most reliable latent heat storage and thermoregulation materials. Phase change materials have been successfully used in the fields of solar energy, aerospace and aviation, environmental control and textiles. Among phase change materials, paraffin and n-alkane are the most popular due to their characteristics of high phase change enthalpy, high energy storage density, relative low volume change ratio, good physical and chemical stability, and no super-cooling or phase segregation behavior. More importantly, there are wide selective working temperature ranges which greatly extend their operating conditions. Microcapsules are considered micro scale containers to prevent core from leaking, isolate from the surroundings and maintain chemical and functional stability in service. There are several methods to synthesize microcapsules: spray dying, complex coacervation, sol-gel, in-situ polymerization, suspension polymerization and emulsion polymerization. Among these, suspension polymerization has the advantages of being simple, cheap, stable, eco-friendly and being easily controlled, which makes it the most popular chemical method to synthesize microcapsules. The majority shell materials of traditional microcapsules are synthetic macromolecules. The properties of shell materials impact the application and processing conditions of the final energy storage composite materials greatly. Nevertheless, the low thermal stability and physical strength of polymers in nature strongly restrict application fields of microcapsules. What’s more, the evaporation or sublimation of core materials causes the low thermal stability. In order to overcome these shortages of shell fracture, core leakage, core evaporation or sublimation existing in traditional microcapsules, we design a copolymer microcapsule with strong interaction force between shell and core parts, which has an unseparated surface layer between shell and core. The strong interaction force between shell and core allows the extreme improvement of thermal stability of microcapsules. The copolymer microcapsule is synthesized by suspension polymerization of behenyl acrylate (BeA) and methyl methacrylate (MMA). In this paper, we report the synthesis, size control and structure analysis of P(BeA-co-MMA) microcapsules which have both excellent thermal stability and high thermal energy storage capacity.

Thermal performance and numerical simulation of geopolymer concrete containing different types of thermoregulating materials for passive building applications

Geopolymer concrete (GPC) containing microencapsulated phase change materials (MPCM) were fabricated in order to achieve a high thermal energy storage capacity of an environmental friendly concrete. Different kinds of MPCM were utilized to investigate the influence of the hygroscopic nature, latent heat, and size of microcapsules on the microstructure and thermal properties of GPC. A combination of polar functional groups on the polymer shell and microcapsules with a small size was found to improve the interface bonds between microcapsules and the GPC matrix, how well the MPCM is dispersed in the GPC, and the thermal insulation properties of the GPC. The energy storage capacity of GPC increases at higher concentrations of MPCM and with a higher latent heat of the MPCM. To determine the thermal impact of buildings utilizing GPC containing MPCM, a numerical model was utilized. The model is based on the implicit finite differences method using an energy balance approach and the heat capacity method. In order to improve the model, a new equation was successfully utilized to fit the specific heat capacity of GPC containing MPCM as function of temperature. The numerical model was verified by experimental measurements of the thermal performance of the GPC. The simulated numerical values obtained for GPC containing MPCM were in good agreement with the experimental data. Higher amounts of MPCM and thicker concrete walls reduce the power consumption needed to maintain an indoor temperature of 23 °C. A power reduction of nearly 35% was achieved when utilizing a 75 mm concrete wall containing 5.2 wt.% MPCM. These building materials are therefore promising for improving human comfort and for reducing the energy consumption of buildings.

Improved thermal properties of stearyl alcohol/high density polyethylene/expanded graphite composite phase change materials for building thermal energy storage

Form–stable phase change materials (FSPCM) with high thermal energy storage capacity and thermal conductivity were manufactured by adding expanded graphite (EG) into stearyl alcohol (SAL) and high density polyethylene (HDPE) mixtures. In the composites, HDPE was used to prevent SAL leakage, and EG was not only a supporting material just like HDPE but also a thermal conductivity promoter. The influences of EG on the thermal properties of the SAL/HDPE phase change materials were investigated with a series of measuring means. Several lines of evidence showed that SAL and HDPE were mixed uniformly and EG was evenly dispersed in the SAL/HDPE composites. Approximately constant melting temperatures of FSPCM at around 57°C and high latent heat of at least 200kJ/kg were presented by the differential scanning calorimeter (DSC). It was found that the leakage rate of the SAL phase change materials decreased obviously when EG was added into the FSPCM. Furthermore, the thermal conductivity of FSPCM with 3% EG could increase up to 0.6698W(mK)−1 while thermal conductivity of FSPCM without EG was only 0.1966W(mK)−1. Finally, the FSPCM with EG could provide considerable thermal energy storage capacity and high thermal conductivity for latent heat storage.

Emulsion‐electrospinning n‐octadecane/silk composite fiber as environmental‐friendly form‐stable phase change materials

ABSTRACTThe ultrafine n‐octadecane/silk composite fibers as form‐stable phase change materials were successfully developed by the emulsion‐electrospinning method. The effect of n‐octadecane content in the emulsion on the morphology and thermal energy storage capacity of the composite fibers were scientifically investigated. Scanning electron microscopy images show that the composite fibers display cylindrical shape with smooth surface and uniform diameter. Differential scanning calorimetry results demonstrate that the composite fibers exhibit reversible phase transition behavior, high thermal energy storage capacity, and good thermal reliability. Meanwhile, the composite fibers exhibit the capability to regulate their interior temperature as the ambient temperature alters according to the thermo‐infrared images. In addition, the composite fibers are friendly to the environment due to the biodegradability of silk. Therefore, the n‐octadecane /silk composite fibers have the great potential application of serving as form‐stable phase change materials for thermal energy storage and thermal regulation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45538.

The Energy Saving and Indoor Comfort Improvements with Latent Thermal Energy Storage in Building Retrofits in Canada

Abstract High-rise apartment buildings in Canada are an integral part of the residential building stock, and their dominance is continuing to grow as their market escalates. Meanwhile, the refurbishment of the existing multi-unit residential building stock is becoming a fundamental step in order to address Canadian energy saving targets. The aim of this paper is to evaluate the effectiveness for energy saving of increasing the thermal capacity of the building enclosure. In particular, thispaperassesses the benefits ofthe adoption of Phase Change Material (PCM) in lightweight constructions in the climates of Toronto and Vancouver. The main aspect investigatedis the contribution of PCM systems to lower the building cooling demand and to increase the indoor thermal comfort. Building simulations aimed at comparing different PCM systemsfor building elements such as floors, ceilings, and walls are reported.Different orientations and internal gains are considered in order to have a complete understanding of the potential benefits of the adoption of systems with high (latent) thermal energy storage capacity in building retrofits in Canada.

Microencapsulated phase change materials for enhancing the thermal performance of Portland cement concrete and geopolymer concrete for passive building applications

Concretes with a high thermal energy storage capacity were fabricated by mixing microencapsulated phase change materials (MPCM) into Portland cement concrete (PCC) and geopolymer concrete (GPC). The effect of MPCM on thermal performance and compressive strength of PCC and GPC were investigated. It was found that the replacement of sand by MPCM resulted in lower thermal conductivity and higher thermal energy storage, while the specific heat capacity of concrete remained practically stable when the phase change material (PCM) was in the liquid or solid phase. Furthermore, the thermal conductivity of GPC as function of MPCM concentration was reduced at a higher rate than that of PCC. The power consumption needed to stabilize a simulated indoor temperature of 23°C was reduced after the addition of MPCM. GPC exhibited better energy saving properties than PCC at the same conditions.A significant loss in compressive strength was observed due to the addition of MPCM to concrete. However, the compressive strength still satisfies the mechanical European regulation (EN 206-1, compressive strength class C20/25) for concrete applications. Finally, MPCM-concrete provided a good thermal stability after subjecting the samples to 100 thermal cycles at high heating/cooling rates.

Radial-like mesoporous silica sphere: A promising new candidate of supporting material for storage of low-, middle-, and high-temperature heat

In the study, polyethylene glycol (PEG), lithium nitrate (LiNO3), and sodium sulfate (Na2SO4) were employed as the low-, middle-, and high-temperature heat storage media, respectively. A series of novel shape-stabilized phase change materials were tailored by a post-preparation method with previously synthesized radial-like mesoporous silica and their structural and thermal properties were characterized. The silica was synthesized through a facile self-assembly process using cetyltriethylammonium bromide as the main template and tetraethyl orthosilicate as silica precursor. The obtained phase change composites showed good shape stability and high thermal energy storage capacity. The morphology and structure of the radial-like mesoporous silica were investigated after combining with different heat storage media. These composites exhibited excellent thermal stability, chemical compatibility, and thermal reliability. The efficient silica support has opened up some new application of energy materials based on novel phase change material/silica composites, such as energy conversion and heat storage for different temperature requirements.

Warming‐Up Effects of Phase Change Materials on Lithium‐Ion Batteries Operated at Low Temperatures

AbstractLithium‐ion battery performance is strongly dependent on thermal conditions, deteriorating dramatically at low temperatures. Herein, a passive thermal management system utilizing RT28/fumed silica composite phase change materials (PCMs) is evaluated for a lithium‐ion battery at temperatures below 5 °C. Taking advantage of the high thermal energy storage capacity, PCMs can store heat and keep a battery warm. The cells with PCMs take much longer before being too cold than cells without PCMs. The improved thermal conditions lead to higher voltages and discharge capacities. In the long term, PCMs increase the average temperature of the battery in continuous cycles and prolong their cycle life by up to 76 %. But the extra thermal mass of the PCM slows the temperature rise so that the cell with PCM fails to perform well at the beginning stages in cold environments.

Sodium-based hydrides for thermal energy applications

Concentrating solar–thermal power (CSP) with thermal energy storage (TES) represents an attractive alternative to conventional fossil fuels for base-load power generation. Sodium alanate (NaAlH4) is a well-known sodium-based complex metal hydride but, more recently, high-temperature sodium-based complex metal hydrides have been considered for TES. This review considers the current state of the art for NaH, NaMgH3−x F x , Na-based transition metal hydrides, NaBH4 and Na3AlH6 for TES and heat pumping applications. These metal hydrides have a number of advantages over other classes of heat storage materials such as high thermal energy storage capacity, low volume, relatively low cost and a wide range of operating temperatures (100 °C to more than 650 °C). Potential safety issues associated with the use of high-temperature sodium-based hydrides are also addressed.