Synthesis of organic phase change materials (PCM) for energy storage applications: A review

Preparation and application of high thermal conductivity phase change microcapsules with fluorescence characteristics based on a ZnWO4 shell

Phase change microcapsules (NePCMs) with high latent heat values, thermal conductivity and stability were synthesized by coating stearic acid (SA) phase change materials (PCMs) with zinc tungstate (ZnWO4) as the shell material. The prepared ZnWO4 and microcapsule samples are characterized through various techniques, and their thermophysical properties under different core-shell ratios and emulsifiers are compared. The highest value that the phase transition enthalpy reaches is 83.63 J g-1 when the core-shell ratio is 1 : 1 and sodium dodecylbenzenesulfonate (SDBS) is adopted as the emulsifier. Based on SEM and TEM results, the regular spherical shape and the complete core-shell structure of the microcapsule can be found, and the particle size ranges between 100 and 300 nm. The thermal conductivity of SA increased by 141.18%-238.43% after using ZnWO4 as the shell material. Moreover, thermogravimetric and leak-proof performance tests demonstrated that microcapsule samples possess high thermal stability. There was no leakage from the six microcapsule samples after heating, proving their potential application in thermal energy storage (TES) under long-term high-temperature conditions. In addition, the cost of ZnWO4 prepared by this method can be reduced by about 40%. According to UV absorption and fluorescence spectrum evaluation, ZnWO4 and microcapsule samples exhibit good photoluminescence and UV absorption properties, indicating that the sample can be widely employed in fluorescent construction, coatings and textile industries at a lower cost.

Improved Thermophysical and Mechanical Properties in LiNaSO4 Composites for Thermal Energy Storage

Solid-solid phase-change materials have great potential for developing compact and low-cost thermal storage systems. The solid-state nature of these materials enables the design of systems analogous to those based on natural rocks but with an extraordinarily higher energy density. In this scenario, the evaluation and improvement of the mechanical and thermophysical properties of these solid-solid PCMs are key to exploiting their full potential. In this study, LiNaSO4-based composites, comprising porous MgO and expanded graphite (EG) as the dispersed phases and LiNaSO4 as the matrix, have been prepared with the aim of enhancing the thermophysical and mechanical properties of LiNaSO4. The characteristic structure of MgO and the high degree of crystallinity of the EG600 confer on the LiNaSO4 sample mechanical stability, which leads to an increase in the Young's modulus (almost three times higher) compared to the pure LiNaSO4 sample. These materials are proposed as a suitable candidate for thermal energy storage applications at high temperatures (400-550 °C). The addition of 5 wt.% of MgO or 5% of EG had a minor influence on the solid-solid phase change temperature and enthalpy; however, other thermal properties such as thermal conductivity or specific heat capacity were increased, extending the scope of PCMs use.

Fabrications, Classifications, and Environmental Impact of PCM-Incorporated Textiles: Current State and Future Outlook

Phase change materials (PCMs) are an extraordinary family of compounds that can store and release thermal energy during phase changes. In recent years, the incorporation of PCMs into textiles has attracted considerable interest, since it represents a unique way to improve the comfort and usefulness of textiles. This article examines the advancements achieved in the preparation, classifications, and environmental effects of PCM-integrated textiles, along with a roadmap for the future. Progress of different PCM has been reported including its pros and cons. In addition, fabrications of the PCM on the apparel have been highlighted. Moreover, this Review analyzed the positive environmental impact of PCM-integrated textiles including improved insulation, extended product lifespan, and energy savings along with negative effects like higher energy consumption in the manufacturing process, added chemical additives tending to have a negative impact on the environment, less disposal features textiles and many more with recent references. Moreover, the future outlook also reports more research on nanoencapsulation, making it energy efficient, ensuring affordability, and more applications in smart PCM textiles. It seeks to stimulate additional research, encourage innovation, and contribute to the creation of high-performance, energy-efficient textiles by investigating the possibilities of PCM-enhanced textiles. The future of PCM in textiles is hopeful, with continuous research and technological advances resolving the aforementioned difficulties.

Healable supramolecular micelle/nano-encapsulated metal composite phase change material for thermal energy storage

Phase change materials (PCMs) have emerged as promising materials for latent heat storage due to their characteristic solid-liquid phase transition behavior during the melting and cooling process. Among them, organic phase change materials are commonly used in latent heat storage. Herein, new phase change self-assembled micelles (PCSM) demonstrated thermal-based phase transition properties. Silver nanoparticles were employed as an additive to improve the thermal properties of the shape-stabilized composite PCSM. The surface morphology and microstructure, general thermal properties and heat adsorption and release behaviors of the samples were characterized with the aid of TEM, SEM, OM, DSC, TGA and DLS techniques. The DSC curve showed that the latent heat adsorption and temperature, heat capacity and thermal reliability of the composite PCSM improved upon the addition of Ag NPs. The TGA curves demonstrated that the presence of Ag NPs increased the onset decomposition temperature and the peak weight loss temperature. PCSM demonstrated low thermal conductivity, whereas the composite PCSM showed better thermal conductivity. This study provides new insight into the promising preparation of healable composite PCMs and their application in thermal energy storage.

Synthesis of PES membranes modified with polyurethane-paraffin wax nanocapsules and performance of bovine serum albumin and humic acid rejection

Membrane fouling is a serious handicap of membrane-based separation, as it reduces permeation flux and hence increases operational and maintenance expenses. Polyurethane-paraffin wax (PU/PW) nanocapsules were integrated into the polyethersulfone membrane to manufacture a composite membrane with higher antifouling and permeability performance against humic acid (HA) and bovine serum albumin (BSA) foulants. All manufactured membranes were characterized by scanning electron microscopy (SEM), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), and contact angle. The contact angle of the pristine polyethersulfone (PES) membrane was measured 73.40 ± 1.32. With the embedding of nanocapsules, the contact angle decreased to 64.55 ± 1.23 for PES/PU/PW 2.0 wt%, and the pure water flux of all composite membranes increased when compared to pristine PES. The pristine PES membrane also has shown the lowest steady-state fluxes at 45.84 and 46.59 L/m2h for BSA and HA, respectively. With the increase of PU/PW nanocapsule ratio from 0.5 to 1.0 wt%, steady-state fluxes increased from 51.96 to 71.61 and from 67.87 to 98.73 L/m2h, respectively, for BSA and HA. The results depicted that BSA and HA rejection efficiencies of PU/PW nanocapsules blended PES membranes increased when compared to pristine PES membranes.

Highly thermal conductive shape-stabilized composite phase change materials based on boron nitride and expanded graphite for solar thermal applications

Phase change heat storage technology is a good way to solve the problem that the temperature of solar hot water outlet is affected by the time domain. A stearic acid (SA)-benzamide (BA) eutectic mixture is a potential phase change material (PCM), but it still has the disadvantages of low thermal conductivity and liquid leakage. In this work, a new high thermal conductive shape-stabilized composite PCM was prepared by adding boron nitride (BN) and expanded graphite (EG) to a melted SA-BA eutectic mixture using an ultrasonic and melt adsorption method, and its phase change temperature, latent heat, crystal structure, morphology, thermal conductivity, chemical stability, thermal stability, cycle stability and leakage characteristics were characterized. The results indicates that the addition of BN and EG significantly improved the thermal conductivity of the SA-BA eutectic mixture, and they efficiently adsorbed the melted SA-BA eutectic mixture. Besides, when the mass fractions of BN and EG are 15 wt% and 20 wt%, respectively, the 15BN20EG composite has almost no liquid phase leakage. When the melting enthalpy and temperature of 15BN20EG are 132.35 J g^-1 and 65.21 °C, respectively, the thermal conductivity of the 15BN20EG is 6.990 W m^-1 K^-1, which is 20.601 times that of the SA-BA eutectic mixture. Moreover, 15BN20EG shows good thermal stability after 100 cycles and good chemical stability below 100 °C. Therefore, the 15BN20EG composite is considered as a potential candidate for solar thermal applications.

Recent applications of phase-change materials in tumor therapy and theranostics

Phase-change materials (PCMs) are a type of special material which can store and release a large amount of thermal energy without any significant temperature change. They are emerging in recent years as a promising functional material in tumor therapy and theranostics due to their accurate responses to the temperature variations, biocompatibility and low toxicity. In this review, we will introduce the main types of PCMs and their desirable physiochemical properties for biomedical applications, and highlight the recent progress of PCM's applications in the modulated release of antitumor drugs, with special attentions paid to various ways to initiate temperature-dependent phase change, the concomitant thermal therapy and its combination with or activation of other therapies, particularly unconventional therapies. We will also summarize PCM's recent applications in tumor theranostics, where both drugs and imaging probes are delivered by PCMs for controlled drug release and imaging-guided therapy. Finally, the future perspectives and potential limitations of harnessing PCMs in tumor therapy will be discussed.

Microencapsulation of polymeric phase change materials (MPCM) for thermal energy storage in industrial coating applications

In recent years, energy has become an important factor in overall development. Most of the energy comes from fossil fuels which are nonrenewable and harmful to our environment. It has become important to develop new application technologies that utilize thermal energy storage (TES) technology. Energy storage technology based on PCMs is a cutting-edge research area with a wide range of potential applications. But the biggest problem of phase change material is its leakage problem, for that the researchers have set up a solution i.e., the microencapsulation techniques. This paper gives an overview of the synthesis of (MPCM) microencapsulated phase change material by using different methodologies and their applications in industrial coatings. Corrosion is the biggest problem in industrial coatings which reduces the working time span and overall performance of the coatings. The incorporation of the micro-PCMs in industrial coatings increases workability as well as the overall performance of the coatings. This review covers the use of MPCM in various industrial coating applications, challenges, and their future directions are also discussed.

A review of the thermal storage of phase change material, morphology, synthesis methods, characterization, and applications of microencapsulated phase change material

In the thermal energy storage area, microencapsulated phase change material (MPCM) is getting more popular among researchers. When phase change materials (PCMs) shift from one phase to another at a specific temperature, a significant quantity of thermal energy is stored. The PCM application focuses on upgrading worldwide energy conservation efforts in light of the rapidly dwindling fossil fuels. The thermal energy supplied by PCM is significantly influenced by the choice of supporting materials and encapsulation methods. A solution to the volume change issues of PCM, phase separation, and leakage is the PCM microencapsulation technique. One of the most common methods to increase the effectiveness of thermal storage material is attained by using PCM with microencapsulation. The preparation processes and thermal characteristics of the MPCM are summarized in this paper. This paper gives information about MPCM with its types, properties, testing, and characterizations. Tables describe specific examples of PCM with thermal properties. Applications in various fields are defined. This review gives as much information to help and be useful for new researchers in the field of thermal management systems to guide their future research.

Vaccine cold chain management and cold storage technology to address the challenges of vaccination programs

The outbreaks of infectious diseases that spread across countries have generally existed for centuries. An example is the occurrence of the COVID-19 pandemic in 2020, which led to the loss of lives and economic depreciation. One of the essential ways of handling the spread of viruses is the discovery and administration of vaccines. However, the major challenges of vaccination programs are associated with the vaccine cold chain management and cold storage facilities. This paper discusses how vaccine cold chain management and cold storage technology can address the challenges of vaccination programs. Specifically, it examines different systems for preserving vaccines in either liquid or frozen form to help ensure that they are not damaged during distribution from manufacturing facilities. Furthermore, A vaccine is likely to provide very low efficacy when it is not properly stored. According to preliminary studies, the inability to store vaccine properly is partly due to the incompetency of many stakeholders, especially in technical matters. The novelty of this study is to thoroughly explore cold storage technology for a faster and more comprehensive vaccine distribution hence it is expected to be one of the reference and inspiration for stakeholders.

Numerical Study of Heat Transfer Enhancement within Confined Shell and Tube Latent Heat Thermal Storage Microsystem Using Hexagonal PCMs

Thermophoresis represents one of the most common methods of directing micromachines. Enhancement of heat transfer rates are of economic interest for micromachine operation. This study aims to examine the heat transfer enhancement within the shell and tube latent heat thermal storage system (LHTSS) using PCMs (Phase Change Materials). The enthalpy–porosity approach is applied to formulate the melting situation and various shapes of inner heated fins are considered. The solution methodology is based on the Galerkin finite element analyses and wide ranges of the nanoparticle volume fraction are assumed, i.e., (0% ≤ φ ≤ 6%). The system entropy and the optimization of irreversibility are analyzed using the second law of the thermodynamics. The key outcomes revealed that the flow features, hexagonal entropy, and melting rate might be adjusted by varying the number of heated fins. Additionally, in case 4 where eight heated fins are considered, the highest results for the average liquid percentage are obtained.

Development of 3D ZnO-CNT Support Structures Impregnated with Inorganic Salts

Carbon-based materials are promising candidates for enhancing thermal properties of phase change materials (PCMs) without lowering its energy storage capacity. Nowadays, researchers are trying to find a proper porous structure as PCMs support for thermal energy storage applications. In this context, the main novelty of this paper consists in using a ZnO-CNT-based nanocomposite powder, prepared by an own hydrothermal method at high pressure, to obtain porous 3D printed support structures with embedding capacity of PCMs. The morphology of 3D structures, before and after impregnation with three PCMs inorganic salts (NaNO₃, KNO₃ and NaNO₃:KNO₃ mixture (1:1 vol% saturated solution) was investigated by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). For structure impregnated with nitrates mixture, SEM cross-section morphology suggest that the inorganic salts impregnation started into micropores, continuing with the covering of the 3D structure surface and epitaxial growing of micro/nanostructured crystals, which led to reducing the distance between the structural strands. The variation of melting/crystallization points and associated enthalpies of impregnated PCMs and their stability during five repeated thermal cycles were studied by differential scanning calorimetry (DSC) and simultaneous DSC-thermogravimetry (DSC-TGA). From the second heating-cooling cycle, the 3D structures impregnated with NaNO₃ and NaNO₃-KNO₃ mixture are thermally stable.

Review on phase change materials for solar energy storage applications

The energy storage application plays a vital role in the utilization of the solar energy technologies. There are various types of the energy storage applications are available in the todays world. Phase change materials (PCMs) are suitable for various solar energy systems for prolonged heat energy retaining, as solar radiation is sporadic. This literature review presents the application of the PCM in solar thermal power plants, solar desalination, solar cooker, solar air heater, and solar water heater. Even though the availability and cost of PCMs are complex and high, the PCMs are used in most solar energy methods due to their significant technical parameters improvisation. This review's detailed findings paved the way for future recommendations and methods for the investigators to carry work for further system developments.

Differential scanning calorimetry-based investigations of erythritol - sodium chloride phase change composites for thermal energy storage

Low thermal conductivity of organic phase change materials (PCMs) for thermal energy storage systems induces the necessity to apply suitable heat transfer enhancement techniques for these materials. The purpose of this study was to improve thermal conductivity of a PCM erythritol by using sodium chloride as an additive, such that the material can be applied for steam cooking systems when integrated with solar parabolic trough collectors. In this study, erythritol-NaCl composites were synthesized by using the melting method, and the key physicochemical properties of the composites were estimated by using differential scanning calorimetry (DSC) coupled with thermo-gravimetric analysis (TGA). The observations indicate that there has been a significant improvement in the thermal conductivity of erythritol supplemented with NaCl. Further, thermal behaviour of the material indicates that it is suitable for steam cooking applications. Furthermore, mathematical models based on the experimental observations can be potentially utilized for further studies of erythritol-NaCl composites.

Enhanced Heat Transfer for NePCM-Melting-Based Thermal Energy of Finned Heat Pipe

Using phase change materials (PCMs) in energy storage systems provides various advantages such as energy storage at a nearly constant temperature and higher energy density. In this study, we aimed to conduct a numerical simulation for augmenting a PCM’s melting performance within multiple tubes, including branched fins. The suspension contained Al₂O₃/n-octadecane paraffin, and four cases were considered based on a number of heated fins. A numerical algorithm based on the finite element method (FEM) was applied to solve the dimensionless governing system. The average liquid fraction was computed over the considered flow area. The key parameters are the time parameter (100 ≤t≤600 s) and the nanoparticles’ volume fraction (0%≤φ≤8%). The major outcomes revealed that the flow structures, the irreversibility of the system, and the melting process can be controlled by increasing/decreasing number of the heated fins. Additionally, case four, in which eight heated fins were considered, produced the largest average liquid fraction values.

Review of Solutions for the Use of Phase Change Materials in Geopolymers

The paper deals with the possibility of using Phase Change Materials (PCM) in concretes and geopolymer composites. The article presents the most important properties of PCM materials, their types, and their characteristics. A review of the latest research results related to their use in geopolymer materials is presented. The benefits of using PCM in building materials include the improvement of thermal comfort inside the building, and also the fact that the additive in the form of PCM reduces thermal gradients and unifies the temperature inside the concrete mix, which can reduce the risk of cracking. The paper also presents a critical analysis related to the feasibility of mass scale implementations of such composites. It was found that the use of PCM in sustainable construction is necessary and inevitable, and will bring a number of benefits, but it still requires large financial resources and time for more comprehensive research. Despite the fact that PCM materials have been known for many years, it is necessary to refine their form to very stable phases that can be used in general construction as well as to develop them in a cost-effective form. The selection of these materials should also be based on the knowledge of the matrix material.

Experimental Studies of the Influence of Microencapsulated Phase Change Material on Thermal Parameters of a Flat Liquid Solar Collector

The article presents the results of preliminary research aimed at determining the possibility of using microencapsulated phase change material (mPCM) slurries as a working fluid in installations with a flat liquid solar collector. In the tests, the following were used as the working fluid: water (reference liquid) and 10% wt. and 20% wt. of an aqueous solution of the product under the trade name MICRONAL® 5428 X. As the product contained 43% mPCM, the mass fraction of mPCM in the working liquid was 4.3% and 8.6%, respectively. The research was carried out in laboratory conditions in the range of irradiance I = 250–950 W/m2. Each of the three working fluids flowed through the collector in the amount of 20 kg/h, 40 kg/h, and 80 kg/h. The working fluid was supplied to the collector with a constant temperature Tin = 20 ± 0.5 °C. It was found that the temperature of the working fluid at the collector outlet increases with the increase in the radiation intensity, but the temperature achieved depended on the type of working fluid. The greater the share of mPCM in the working liquid, the lower the temperature of the liquid leaving the solar collector. It was found that the type of working fluid does not influence the achieved thermal power of the collector. The negative influence of mPCM on the operation of the solar collector was not noticed; the positive aspect of using mPCM in the solar installation should be emphasized—the reduced temperature of the medium allows the reduction in heat losses to the environment from the installation, especially in a low-temperature environment.

Application and research progress of phase change materials in biomedical field

Phase change materials (PCMs) are widely used in solar energy utilization, industrial waste heat recovery and building temperature regulation. However, there have been few studies on the application of PCMs in the field of biomedicine. In recent years, some scholars have carried out research in the biomedicine field using the characteristics of PCMs. It was observed that the excellent properties of PCMs enhance the quality of a variety of biomedical applications with many advantages over existing applications, which provide new methods for the treatment of disease. PCMs have broad application prospects in the field of biomedicine. Therefore, a timely review of relevant research progress is of great significance for the continuous development of new methods. Innovatively, from the unique perspective of the biomedical field, this paper systematically reviews the application and related research progress of PCMs from four aspects: cold chains for vaccines and medicines, drug delivery systems, thermotherapy/cold compress therapy and medical dressings. In addition, we summarize and discuss the general principles of the design and construction of PCMs in the biomedical field. Finally, existing problems, solutions and future research directions are also put forward in order to provide a basis for guidance and promote the future applications of phase change materials in the biomedicine field.

Experimental Investigation of the Apparent Thermal Conductivity of Microencapsulated Phase-Change-Material Slurry at the Phase-Transition Temperature

The article presents the results of detailed studies of the thermal conductivity of the water slurry of microencapsulated PCM (mPCM) and slurry based on water–propylene glycol solutions. The starting product, MICRONAL^® 5428 X, which contains about 43% microencapsulated paraffin with a transformation temperature of 28 °C, was mixed with the base liquid to obtain slurries with mass fractions of mPCM of 4.3, 8.6, 12.9, 17.2, 21.5, 25.8, 30.1, 34.4, 38.7, and 43.0%. Detailed measurements were carried out in the temperature range of 10–40 °C. It was found that: (a) an increase in the temperature of the slurry caused an increase in its thermal conductivity, both when PCM was in the form of a solid and a liquid; (b) the thermal conductivity of the mPCM slurry when the PCM was in liquid form was greater than the thermal conductivity of the slurry when the PCM was liquid; (c) during the phase transformation, a significant increase in the thermal conductivity of the slurry was observed, and its peak occurred when the temperature of the slurry reached the temperature declared by the manufacturer at which the phase-transition peak occurs.

The Impact of Heat Exchangers’ Constructions on the Melting and Solidification Time of Phase Change Materials

An application of latent heat thermal energy storage systems with phase change materials seems to be unavoidable in the present world. The latent heat thermal energy storage systems allow for storing excessive heat during low demand and then releasing it during peak demand. However, a phase change material is only one of the components of a latent heat thermal energy storage system. The second part of the latent heat thermal energy storage is a heat exchanger that allows heat transfer between a heat transfer fluid and a phase change material. Thus, the main aim of this review paper is to present and systematize knowledge about the heat exchangers used in the latent heat thermal energy storage systems. Furthermore, the operating parameters influencing the phase change time of phase change materials in the heat exchangers, and the possibilities of accelerating the phase change are discussed. Based on the literature reviewed, it is found that the phase change time of phase change materials in the heat exchangers can be reduced by changing the geometrical parameters of heat exchangers or by using fins, metal foams, heat pipes, and multiple phase change materials. To decrease the phase change material’s phase change time in the tubular heat exchangers it is recommended to increase the number of tubes keeping the phase change material’s mass constant. In the case of tanks filled with spherical phase change material’s capsules, the capsules’ diameter should be reduced to shorten the phase change time. However, it is found that some changes in the constructions of heat exchangers reduce the melting time of the phase change materials, but they increase the solidification time.

The Impact of Additives on the Main Properties of Phase Change Materials

The main drawback of phase change materials (PCMs) is their low thermal conductivity, which limits the possibilities of a wide range of implementations. Therefore, the researchers, as found in the literature, proposed several methods to improve the thermal conductivity of PCMs, including inserting high thermal conductivity materials in nano-, micro-, and macro-scales, as well as encapsulation of PCMs. However, these inserts impact the other properties of PCMs like latent heat, melting temperature, thermal stability, and cycling stability. Hence, this paper aims to review the available in the open literature research on the main properties of enhanced PCMs that undergo solid–liquid transition. It is found that inserting high thermal conductivity materials and encapsulation results in improved thermal conductivity of PCMs, but it decreases their latent heat. Moreover, the insertions can act as nucleating agents, and the supercooling degree can be reduced. Some of the thermal conductivity enhancers (TCEs) may prevent PCMs from leakage. However, some test results are inconsistent and some seem to be questionable. Therefore, this review indicates these discrepancies and gaps in knowledge and points out possible directions for further research.

Thermal energy storage and thermal conductivity properties of Octadecanol-MWCNT composite PCMs as promising organic heat storage materials

Fatty alcohols have been identified as promising organic phase change materials (PCMs) for thermal energy storage, because of their suitable temperature range, nontoxicity and can be obtained from both natural and synthetic sources. Like all other organic PCMs, octadecanol (OD) as PCM suffers from low thermal conductivity (TC). In this work, to enhance its TC, it was grafted on the functionalized MWCNT and were used as a conductive filler to enhance overall thermal properties of OD in a composite PCM (CPCMs) structure. The OD/OD-g-MWCNT sample showed better dispersion within the composites and the presence of additional OD boosted the overall heat storage enthalpy compared to that of plane composite sample with OD/MWCNT. In a non-quantitative approach, it was observed that, any increase in grafting ratio of OD increases the heat storage enthalpy of the composites. The heat storage enthalpy of (267.7 J/g) OD/OD-g-MWCNT(4:1)-5wt% composite PCM had reached very close to the heat storage enthalpy value of pure OD (269.3 J/g), and much higher than that of OD/MWCNT-5wt% (234.5 J/g). Champion sample i.e. OD/OD-g-MWCNT (4:1)-5wt%, showed good heat storage enthalpy, cycling performance, thermal stability and TC enhancement by 262.5%.