Phase Change Material Research Articles

New methodological approach for the mechanical testing of aerial lime-based binders and mortars: the effect of PEG-1000 addition

So far, the mechanical testing at the macro scale of aerial lime-based materials has mainly been focused on the analysis of mortars, while binder specimens have not been studied as much. In the present work an alternative, material-effective and low-waste methodology to evaluate the mechanical properties of aerial lime binders and mortars is proposed. The core of this methodology is based on specimen size reduction, minimizing quantities of material required during development and testing. In particular, the proposed methodology is aimed at studying the interaction of different quantities of a phase change material (PCM) with aerial lime binders and mortars. The mechanical properties of pure aerial lime binders were successfully characterized, whereas mortar specimens provided less detailed information. The mechanical characterization showed that aerial lime binders, and consequently mortars, are weakened in the presence of Poly(ethylene glycol) - PEG, a PCM. It was observed that 8 % of PEG in the binder lower the resistance to compression by 36 %, resistance to scratch on 76 % and flexural resistance by 32 %. Finally, this study also proposes a model for the physical interaction between the PCM and the aerial lime-binder to explain the observed weakening mechanism: PEG can hinder the correct crystalline interlocking between the calcite crystals in the carbonated binder, and act as a lubricant promoting their sliding under compressive forces.

Preparation and characterization of modified steel slag-based composite phase change materials

In order to promote the resource utilization in steel slag and reduce the environmental hazards caused by steel slag, a steel slag-based composite phase change material was prepared in this experiment. Steel slag had a porous structure with good structural stability, which could be used to prepare composite phase change materials and applied in fields such as thermal energy storage and waste heat recovery. To enhance the adsorption capacity of steel slag on phase change materials, the impact of acid or alkali modifiers on steel slag was meticulously examined. The investigation revealed that the pore structure of the modified steel slag was markedly enhanced, accompanied by a notable improvement in adsorption capacity. Among the results, the adsorption rate of the acid washed modified steel slag for paraffin reached 35 %, with the phase change temperature and latent heat of phase change being 53 °C and 60 J/g. Acid washing had a significant impact on the pore structure of the steel slag, with the adsorption rate of the acid washed modified steel slag for paraffin being approximately twice that of the unmodified steel slag.

AN ASSESSMENT OF PHASE CHANGE MATERIAL, PREPARATION TECHNIQUES AND CONTAINMENT MATERIAL WITH DIFFERENT MOLTEN SALTS FOR THERMAL ENERGY STORAGE SYSTEM

Molten salts are extensively used as high-temperature heat transfer media and thermal energy storage (TES) materials in concentrating solar power (CSP) plants. Molten salt corrosion is a critical factor influencing the safe operation of the system. This work comparatively summarizes various factors influencing molten salt corrosion, including temperature, impurities, alloy composition and gas atmosphere. Additionally, the corrosion mechanisms of nitrate, carbonate, chloride, and fluoride-based mixture salts are meticulously reviewed. The demand for high-temperature storage is indeed increasing, driven by the need for more efficient and sustainable energy solutions. High-temperature storage systems, particularly those utilizing phase change materials (PCMs) and molten salts, play a key role in enhancing energy efficiency and reducing carbon footprint. By improving the efficiency of energy storage and reducing the need for fossil fuels, high-temperature storage systems help decrease greenhouse gas emissions, contributing to the fight against global warming. The paper focused on enhancing the corrosion resistance of container materials in terms of improving PCM thermal conductivity and stability.

Enhanced energy efficiency by implementing MHD flow and heat transfer in Cu-Al2O3/H2O hybrid nanoparticles with variable viscosity

Hybrid nanofluids are engaged in phase-change materials and thermal energy storage systems to enhance heat transfer during the charging and discharging processes. Improved understanding of how variable viscosity and thermal radiation affect these fluids contributes to more efficient energy management. This study aims to formulate an efficient mathematical model for the two-dimensional flow of a hybrid nanofluid composed of copper (Cu) and alumina oxide (Al2O3) suspended with base fluid H2O to form a hybrid fluid under the influence of thermal radiation. The present study also integrates the effects of variable viscosity and viscous dissipation. Electromagnetic radiation impact due to temperature also amalgamated. The governing PDEs are reformulated into ODEs via tailored similarity transformations. These reformulated equations are then numerically resolved using Bvp4c solver, leveraging the shooting method within MATLAB for precision and efficiency. The most significant results are predetermined relevant parameters, such as the prosperity parameter, magnetic parameter, radiation parameter, slip velocity parameter,Biot number, convention parameter, Eckert number, heat source parameter, Prandtl number on velocity and temperature distribution are inspected graphically and in the form of table. Outcomes illustrate that fluid velocity flattens by increasing magnetic parameters because there exists a Lorentz force that opposes the fluid motion, whereas enhancement is noted via radiation parameter. Compared to conventional nanofluid, temperature curves of hybrid nanoliquid is higher. Furthermore, recent results indicate strong agreement for a specific instance.

Highly Stable Composite Phase-Change Materials Reinforced by Silica Aerogels and Cellulose Nanocrystals for Enhanced Thermal Insulation and Durable Isoperibolic Application

Highly Stable Composite Phase-Change Materials Reinforced by Silica Aerogels and Cellulose Nanocrystals for Enhanced Thermal Insulation and Durable Isoperibolic Application

Investigation of phase change material based cool pack performance in vests for personalized thermal comfort in extremely hot climatic conditions: Model development and case studies

Vests with provisions for carrying multiple phase change material (PCM) based cool packs are one of the possible ways to provide personalized thermal comfort in extremely hot climatic conditions. Although this passive cooling mechanism is simple to implement, there are several challenges associated with the design of these heat packs. For instance, the heat packs must maintain the skin temperature within the comfortable range of 33±2Co (87.8-95 Fo) for the desired duration while also being as lightweight as possible. For the heat pack design, it is important to consider not only the hot climatic condition that causes heat to flow from ambient to body surface but also the heat generation from the body itself for different activity levels, such as reclining, standing, walking, jogging, running, and so on. In the present work, a numerical framework has been developed and experimental validation performed to investigate the performance of cool packs when it is loaded with any one of the following five PCMs, namely Ice, savE OM 21, Coconut oil, C18 paraffin, and Octadecane. The comparative performance of these cool packs is assessed based on the comfort duration for which they can maintain the body surface temperature within the specified range of 33±2Co. SavE OM21 PCM exhibited excellent performance in terms of providing thermal comfort more precisely. However, thermal conductivity must be enhanced from 0.14-0.21 W/mK to 1.0 W/mK. The lower masses of C18 paraffin and Octadecane PCM were deemed suitable for practical use in real-world scenarios.

Form-Stable Phase-Change Materials Using Chemical Vapor Deposition-Derived Porous Supports: Carbon Nanotube/Diatomite Hybrid Powder and Carbon Nanotube Sponges

In this work, two types of chemical vapor deposition (CVD)-derived porous supporting materials consisting of CNTs–decorated diatomite (CNT/DE) and CNT sponges (CNS) were developed to prepare novel form-stable phase-change material (PCM) composites by impregnation, using polyethylene glycol (PEG) as the PCM. The CNT/DE support matrix showed highly entangled nanotubes (the weight ratio of CNTs to DE was 0.16) over and inside the porous structure of diatomite, giving the hybrid matrix an electrical response. The CNS that resulted was mainly composed of bent and interconnected CNTs forming a three-dimensional highly porous structure. XPS and FTIR results revealed that CNTs in both the supporting materials have a moderate amount of oxygen-containing functional groups. Both hosts allow for high PEG loading (about 75 wt%) without showing any PCM leakage during melting. Both form-stable PCM composites showed high thermal reliability upon a hundred melting–solidification DSC cycles (PEG/CNT/DE latent heat is 86 ± 4 J/g and PEG/CNS latent heat is 100 ± 2 J/g; melting temperature 34 °C). An analytical model was used to evaluate the passive cooling performance of the systems, simulating the thermal behaviour of a building wall containing the confined PCM in the hosts, resulting in a reduction in required cooling power of about 10%. The overall results suggest that the developed form-stable PCM composites could be considered promising additive materials for the production of building envelopes with thermal energy storage capability.

Structure optimization of U-tube solar collector integrated with phase change materials

Solar collectors are significantly influenced by weather conditions, leading to a mismatch between thermal energy production and demand. To mitigate this issue, U-tube solar collectors integrated with phase change material (PCM) were investigated to store excess solar energy and regulate the temperature of collectors. This study investigates the effects of fin spacing and fin length on the heat transfer performance of these collectors under various conditions. Additionally, the impact of different collector tube lengths was analyzed. The results show that adding fins in solar collectors enhances temperature distribution uniformity and accelerates the PCM melting process. And the addition of fins to the U-tube produces faster temperature increase and significant improvement of temperature uniformity. In configurations featuring with fin length 20 mm and fin spacing 30 mm, the average PCM temperature decreased by 9.4 % and the liquid fraction decreased by 10.2 %, compared with non-finned. Smaller fin spacing or longer fins can improve heat transfer efficiency, and reduce PCM temperatures and liquid fractions. The 2L configuration exhibited optimal performance with an average PCM temperature of 330 K and a liquid fraction of 0.60 and achieved a significant reduction in time to reach 318 K by 47.9 % when compared to the L configuration.

Enhanced thermal storage performance with non-linear porosity distribution in copper foam-PCM composites

Phase change materials (PCMs) are increasingly utilized in thermal energy storage systems due to their high energy density and capability to maintain a constant temperature during phase transitions. However, the low thermal conductivity of PCMs poses a significant challenge, often mitigated by embedding PCMs within high-conductivity metal foams. While linear and layered porosity distributions in metal foams have been extensively studied, the potential benefits of non-linear porosity distributions remain underexplored. This study aims to bridge this gap by numerically investigating the effects of non-linear porosity distributions of copper foam on the melting behavior and thermal performance of palmitic acid. The paper thoroughly explains how different melting regimes influence the optimal choice of porosity distribution. Using the Enthalpy-Porosity approach and the Local Thermal Non-Equilibrium model, various positive and negative porosity gradients in both x and y directions were examined. The results demonstrate that positive porosity gradients significantly improve the melting rate and energy storage performance. Specifically, a positive gradient in the x-direction reduced the melting time by 10.4 %, while a positive gradient in the y-direction achieved a 16.74 % reduction compared to uniform porosity configuration. Building on these findings, the study then explores two-dimensional (2D) porosity distribution optimization, leading to further enhancements. The optimized 2D configuration achieved a 22.67 % reduction in melting time and a 32.38 % increase in the average energy storage rate compared to the uniform porosity scenario.

Preparation and application of multilayered flexible phase change material with high thermal conductivity and high enthalpy

Phase change material (PCM) uses latent heat to store heat and are widely used in thermal management of electronic components. However, endowing PCM with high thermal conductivity and high enthalpy remains a challenge. This study designs a multilayered structure, paraffin (PA)/styrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer (SEBS) (PA/SEBS) and PA/SEBS/expanded graphite (EG) (PA/SEBS/EG) are prepared by melt blending and crosslinked together in sequence, named 0EG@6EG. The results show that the enthalpy value of 0EG@6EG is as high as 167.46 kJ·kg−1, and the thermal conductivity has been improved compared to traditional uniform structure. 0EG@6EG has a certain degree of self-healing ability, and the contact surface between layers could withstand a tensile strength of 0.23 MPa. The passive experiment indicates that the temperature rising rate of 0EG@6EG is 4.08 % higher than that of PA/SEBS/3EG. The active experiment shows that the highest outlet temperature difference between 0EG@6EG and PA/SEBS/3EG is 1.52 °C, and the heat released is 26.73 % higher than that of PA/SEBS/3EG. The optimal thickness ratio between PA/SEBS/0EG to PA/SEBS/6EG in 0EG@6EG is 1.2:0.8, and when the active system contacts with the layer of PA/SEBS/6EG, it is conducive to enhance heat transfer. This work provides a reference for increasing the thermal conductivity of PCM without decreasing enthalpy value.

Phase change foam with temperature-adaptive radiative cooling feature for all-day building energy saving

Radiation cooling is an emerging energy-saving technology that requires a minimal energy input to achieve passive cooling. To date, the majority of research has focused on maximizing the cooling power. However, a powerful cooling performance may lead to overcooling at night or during cold seasons. In this study, we developed a phase change radiation cooling material (PCRCM) with temperature-adaptive cooling features to meet dynamic cooling requirements. Polydimethylsiloxane was selected as the flexible thermal emission substrate, while boron nitride nanosheets were chosen as the optical fillers. Consequently, radiation cooling materials exhibiting 97.5% reflectance and 94% emissivity were achieved. The phase change material (PCM) was then loaded onto the foam as an optical and thermal buffering medium. The obtained PCRCM exhibited 96% reflectance in hot atmosphere and 82.6% reflectance in cold atmosphere, passively cooling through thermal emission and PCM endotherms during the daytime, and actively heating through PCM exotherms at nighttime. Simulation and outdoor tests demonstrated that the PCRCM shows an excellent building energy-saving potential in different seasons.

Building the Future: Integrating Phase Change Materials in Network of Nanogrids (NoN)

Building the Future: Integrating Phase Change Materials in Network of Nanogrids (NoN)

Millimeter-scale macrocapsules with cold energy storage and temperature indication for vaccine storage

This study aims to prepare millimeter-scale macrocapsules with cold energy storage and temperature indication suitable for the requirement of vaccine storage (−25 °C ∼ -15 °C). In these macrocapsules, reversible thermochromic microencapsulated phase change materials (TC-MPCMs) are used as dispersions, and flexible calcium alginate is served as the polymer matrix. Macrocapsules exhibit a particle size distribution from 0.5 mm to 3.0 mm, with a melting temperature of −18.4 °C, a melting enthalpy of 86.0 J/g and an encapsulation efficiency of 45.5 %. After melting of the PCMs (Phase change materials), these macrocapsules can undergo a reversible discoloration, with a color difference of 27.54. Additionally, the volatilization of internal PCMs can also trigger the discoloration reaction. After 100 thermal cycles, the latent heat loss of the macrocapsules is less than 5 %, and the calcium alginate shell material delays the thermal decomposition of internal PCMs. Finally, the storage-release cold energy test shows that at 25 °C, the macrocapsules can maintain the ideal temperature range (−25 °C ∼ -15 °C) for 10.34 min. The millimeter-scale macrocapsules successfully address the issues of ultrafine powder contamination, difficulty in reuse and recycling of micron-scale TC-MPCMs, and show excellent potential for vaccine frozen storage.

Switchable Narrowband Diffuse Thermal Emission With an In3SbTe2‐Based Planar Structure

AbstractTailoring of thermal radiation is critical for applications like daytime radiative cooling, thermophotovoltaic energy conversion, and gas sensing. Phase‐change materials (PCMs) offer an additional degree of freedom, enabling reconfigurable thermal emission by actively triggering phase transitions. In particular, In3SbTe2 (IST) features a unique non‐volatile phase transition in the infrared between an amorphous dielectric state and a crystalline metallic state. Although efficient and easily manufacturable alternatives to conventional infrared light sources will be highly desirable, achieving narrowband and diffuse emission using a simple, lithography‐free structure incorporating PCMs for dynamic functionalities has remained elusive. Here, a planar reconfigurable narrowband thermal emitter using an IST layer on top of a Salisbury screen is demonstrated. The design achieves high emissivity around the ambient thermal wavelength in the amorphous phase and low emissivity in the crystalline phase, featuring angle‐ and polarization‐independent behavior. Multiple patterns are optically written into the IST layer, demonstrating centimeter‐scale programmability as well as a resolution of 20 µm. This work paves the way toward reconfigurable and easily manufacturable devices, showing potential for applications in labeling and anticounterfeiting.

Investigating the impact of fin configuration on phase change material melting in square cells: A numerical study

This investigation thoroughly explores the effects of different fin arrangements on the melting behavior of phase change materials (PCMs), specifically paraffin wax (RT42), within a 50 × 50 mm2 square cell. Three distinct cases are considered: Case 1 involves no fins, Case 2 incorporates straight rectangular fins, and Case 3 employs undulated fins. To simulate real-world thermal energy storage conditions, the PCM container is thermally insulated, preventing external heat leakage. The primary objective is to identify the optimal fin arrangement to enhance latent heat storage system efficiency by improving both melting and solidification processes. The novelty of this research lies in the detailed analysis of various undulated fin geometries and their placements, which have not been extensively explored in previous studies. Numerical simulations were conducted using the ANSYS FLUENT solver. The progression of PCM melting was evaluated via the ANSYS design modeler based on the finite volume method, incorporating transient heat conduction and free convection. The results demonstrate that optimized undulated fin configurations can significantly enhance the melting process by promoting uniform temperature distribution and improving heat transfer rates, thereby reducing melting time. This study provides valuable insights for designing efficient latent heat energy storage systems, contributing to advancements in energy management and sustainable technologies.

Homeostatic Microfiber-Composed Synthetic Leathers with Chemical Robustness and Undercooling Self-Regulation.

Homeostatic microfiber leathers with temperature self-regulation promise broad applications, ranging from the apparel and automotive interior industries to the home furnishing and healthcare industries. Temperature self-regulation is achieved by phase-change materials containing microcapsules introduced within the leathers. The introduction of phase change microcapsules (PCMs) into microfiber leather faces two formidable challenges: (1) the shell of microcapsules must remain chemically stable against alkalis and organic solvents; (2) PCMs possess the ability to reduce supercooling during which latent heat is released, allowing for the precise and controllable release of latent heat. Here we present a high-performance homeostatic microfiber-composed synthetic leather containing PCMs that can address these two challenges, which not only demonstrate exceptional chemical robustness under alkaline conditions but also offer efficient and precise control over temperature fluctuation and latent heat release by reducing supercooling. Titanium carbide (TiC) known for its high thermal conductivity and alkali resistance has been selected as the shell material for the microcapsules, which can effectively resolve chemical stability issues. Meanwhile, the high thermal conductivity of TiC can be leveraged to enhance heterogeneous nucleation, thus narrowing the temperature range for latent heat release. The resultant microfiber leather shows outstanding capabilities for adjustable thermal energy storage. Our studies offer an effective approach to create homeostatic microfiber-composed synthetic leathers with chemical robustness and undercooling self-regulation, which would be useful in the fields of the textile, biomedical, and healthcare industries.

Interfacial Engineering of Biocompatible Nanocapsules for Near-Infrared-Triggered Drug Release and Photothermal Therapy.

Chemotherapy is an effective option for cancer treatment. However, its clinical application is often limited by the severe side effects of chemical drugs. To overcome these limitations, a novel drug-loaded phase-change nanocapsule system is developed. These nanocapsules are assembled via one-step electrostatic self-assemblythrough guided interfacial engineering. The phase change material core nanocapsules demonstrate great photothermal-controlled drug release performance and exhibit excellent tumor-targeting drug delivery performance both in vitro and in vivo via the binding of hyaluronic acid shell on the nanocapsule surface with corresponding receptors on the tumor cell membrane. The phototherapy function of the nanocapsules enhances immune activation within the tumor microenvironment, as demonstrated by flow cytometry and multiplex immunohistochemistry. The developed nanocapsules are biocompatible, versatile, and scalable and offer a promising smart delivery platform for controllable near-infrared triggered drug release and photothermal therapy.

An Experimental Investigation of the Effect of Phase Change Material and External Reflectors on the Performance of a Single Slope Still

Solar stills are widely recognized as a cost-effective and eco-friendly solution for transforming brackish water into potable water. Although solar energy shows promise, it has yet to be widely adopted due to its lower productivity. This paper presents an experimental investigation to enhance the performance of a single slope solar still using phase change material (PCM) and external reflectors. Many outdoor experiments have been conducted for three cases including: solar still without PCM, Solar still with PCM, and solar still with PCM with external reflectors. Also, the effect of water depth inside the still is examined. The performance of the four cases is evaluated and compared under the meteorological conditions of Baghdad City, Iraq. The results showed that using the PCM improved the Accumulated yield of the conventional solar still by 23% and 14 % for water depths of 2 cm and 3 cm, respectively. Also, the results revealed that using the external reflectors improves the Accumulated yield by 15% for the still with PCM, respectively.

The Confinement Behavior and Mechanistic Insights of Organic Phase Change Material Encapsulated in Wood Morphology Genetic Nanostructures for Thermal Energy Storage.

Wood, a renewable and abundant biomass resource, holds substantial promise as an encapsulation matrix for thermal energy storage (TES) applications involving phase change materials (PCMs). However, practical implementations often reveal a disparity between observed and theoretical phase change enthalpy values of wood-derived composite PCMs (CPCMs). This study systematically explores the confinement behavior of organic PCMs encapsulated in a delignified balsa wood matrix with morphology genetic nanostructure, characterized by a specific surface area of 25.4 ± 1.1 m2/g and nanoscale pores averaging 2.2 nm. Detailed thermal performance evaluations uncover distinct phase change behaviors among various organic PCMs, influenced by the unique characteristics of functional groups and carbon chain lengths. The encapsulation mechanism is primarily dictated by host-guest interactions, which modulate PCM molecular mobility through hydrogen bonding and spatial constraints imposed by the hierarchical pore structure of the wood. Notably, results demonstrate a progressive enhancement of nanoconfinement effects, evidencing a transition from octadecane to stearic acid, further supported by density functional theory (DFT) calculations. This research significantly advances the understanding of nanoconfinement mechanisms in wood-derived matrices, paving the way for the development of high-performance, shape-stabilized composite PCMs that are essential for sustainable thermal energy storage solutions.

Assessment of thermal behavior for storage material filled in annulus coaxial aluminum pipes and inserted in evacuated tube collector: An experimental and mathematical investigation

This research paper presents a comprehensive evaluation of an evacuated tube solar air heater (ETSAH) integrated with annulus coaxial aluminum pipe (ACALP) and phase change material (PCM). The experimental setup includes evacuated tubes and double aluminum pipes welded at the bottom and filled with PCM annularly to enhance thermal storage capacity. Experimental data and mathematical models are used to assess heat transfer techniques, power gain, and the thermal behavior of the PCM and the ETSAH. The combination of experimental results and mathematical models provides validation and reliability of the thermal characteristics by utilizing the ACALP additive. The results indicate maximum outlet temperatures of 105 °C, 97 °C, and 89 °C at flow rates of 0.006, 0.01 and 0.05 kg/s, respectively. The PCM temperature is gradually influenced by air flow rate and heat flux, which increases within the day, reaching a maximum at 14:00 of 90 °C and 93 °C of air flow rate 0.05 and 0.006 kg/s, respectively. Moreover, the maximum actual power gained from the device is 2261 W at 0.05 kg/s of air flow rate. A comparison between experimental and numerical values shows an average relative error of 3.84 %. Hence, that indicates that the mathematical model can be considered suitable for predicting the power gained by the proposed ETSAH.