Phase Change Material Research Articles

Analysis and optimization of dynamic and static thermal rectification in shell-and-tube phase change thermal rectifiers

Thermal rectification devices based on solid-liquid phase change material (PCM) can realize efficient and reversible control of forward and reverse heat flux. In this study, an analytical solution for a shell-and-tube phase change thermal rectifier is derived based on Fourier's law of heat conduction. The validity of the analytical model is confirmed by the numerical model verified by the exact solution of the single-phase Stefan problem. The influence of thermophysical properties, structural parameters, and initial temperature on the dynamic and static thermal rectification effects of the shell-and-tube heterojunction composed of polydimethylsiloxane (PDMS) and hexadecane (C16) is investigated and optimized. Results indicate that the proposed analytical model for the shell-and-tube phase change thermal rectifier enables rapid and precise prediction of thermal rectification effects. The presence of solid-liquid phases of C16 under forward and reverse heat transfer modes reduced the thermal resistance difference, resulting in poor initial rectification performance (only about 1.17). The optimized thermal rectification effect is significantly increased to 1.56, which is significantly improved by 33.56 %. Moreover, the dynamic rectification effect of the shell-and-tube thermal rectifier is notably higher than the static rectification effect. The average dynamic thermal rectification ratio within the first 50 s before and after optimization is 2.19 and 7.80, respectively, which is several times higher than the static thermal rectification ratio. This paper further analyzes the impact of initial temperature and finds that an increase in initial temperature can further enhance the dynamic thermal rectification effect. Raising the initial temperature to 5 K above the phase change temperature can increase the improvement of the dynamic rectification effect to 256.36 % in the first 50 s. The significance of this study lies in its potential to advance the understanding and practical application of thermal rectification based on PCM.

How can phase change materials improve vehicle cooling systems for better motor efficiency and thermal management?

Phase change materials, or PCMs, have become an attractive option for improving thermal management in the vehicle industry. With the increasing demand for efficient cooling systems and improved driving ranges in electric vehicles, PCMs offer an innovative approach to managing heat dissipation and improving performance. While PCMs are already applied in industries such as construction, their potential to revolutionize automotive thermal management could lead to advancements in all aspects of the field. They are a perfect option for increasing energy efficiency because of their capacity to collect and release thermal energy. This study explores the application of PCMs in vehicles and assesses their effectiveness in improving cooling systems.

Performance analysis of photovoltaic module using eutectic phase change material

ABSTRACT Geographical factors and environmental variables affect the performance of the solar photovoltaic (SPV) system. The incident solar radiation on the SPV will generate power and increase the surface temperature. Thermal regulation is needed for the SPV system to enhance its performance. In this work, a passive cooling approach is adopted to reduce the surface temperature of the SPV system. The eutectic phase change material is synthesized with the composition of RT35 paraffin wax and sodium sulfate decahydrate. The thermophysical properties of the eutectic mixture are analyzed using a differential scanning calorimeter, and thermal conductivity is measured. The developed eutectic PCM is integrated into the SPV modules’ rear-side packing in the aluminum container. The output of the PV module is increased by 10% and up to 6.1°C reduces the surface temperature of the SPV module compared to the conventional SPV system.

Research Developments and Applications of Ice Slurry

Ice slurry is a phase-changing material composed of liquid water, ice crystals, and a freezing point depressant. It is finer and more uniform compared to ice cubes or flake ices and is used in many industries, such as food preservation, comfortable cooling, medical protective cooling, sport cooling, instrument cooling, firefighting, and artificial snowmaking, due to its high energy storage density. Ice slurry with high concentration can be used for cleaning equipment as its friction is several times greater than that of water at the same flow rate. This paper describes in detail the developments of ice slurry, including production methods, concentration measurement approaches, flow and heat transfer characteristics, as well as its applications in various industries. Problems to be solved or improved are also discussed, providing suggestions for better developments and applications in industrial environments.

Assessing the Impact of Phase-Change Materials on Enhancing the Thermal Efficiency of Buildings in Tropical Climates

Civil construction and buildings account for a significant 36% of worldwide energy consumption, contributing to 37% of global CO2 emissions. In Brazil, buildings consume a substantial 51.2% of the nation’s electricity production. Remarkably, approximately one-third of this energy is allocated specifically for maintaining thermal comfort within these structures. The thermal performance of a building has a significant impact on its energy efficiency; in this way, technologies developed to contribute to the energy efficiency of envelopes can directly contribute to the reduction in the building’s overall energy consumption. PCMs are technologies capable of absorbing heat without increasing temperature and can contribute to the better energy performance of envelopes. PCMs are used as a thermal performance solution in cold climate regions, and studies show that they are likely to work in buildings in tropical climates. The objective of this work is to analyze the performance of PCMs in tropical regions of the southern hemisphere, specifically in Brazil, and their behavior according to the constructive system used. Computer simulation contributes to an analysis closer to the reality of the implementation of this technology in these regions. This work is carried out with simulations in the software EnergyPlusTM version 24.1. The results demonstrate that PCMs can effectively contribute to a reduction in energy consumption for the thermal comfort of buildings in tropical climates, demonstrating the possible feasibility of the development of this technology for tropical climates.

Development of PCM tile for residential buildings in hot and dry climate: design and optimization

In recent years, the building sector has become more conscious of sustainability, and the use of phase change materials (PCMs) in concrete has gained more attraction. Integration of PCM with building facades is a successful method to reduce energy consumption and improve human comfort. However, no single PCM can work in an all-weather scenario. Hence, in this research work, an attempt is made to select a suitable PCM for Chennai city, India, and this methodology can be employed at any geographical location. The PCM tile is designed by including certain features to increase the thermal conductivity of the PCM zone. The optimum design of the PCM tile is achieved through multi-objective optimization techniques. L27 orthogonal array is employed, and all the tests were conducted through validated numerical simulation. Redesigned PCM tile includes a PCM layer of 2 cm thickness with a 10% mix of copper nanoparticles covered by plaster. Redesigned PCM tile reduces the peak indoor temperature by 6.62℃ compared with conventional roof systems.

Numerical and experimental study of thermal stabilization system for satellite electronics with integrated phase-change capacitor

In this paper experimental and numerical investigations were conducted to analyze the application of phase change material (PCM) for temperature stabilization of small satellite electronics. The reference electronic equipment is a data processing unit generating a nominal power of 9.6 W during its operation. To stabilize its temperature, an integrated PCM module was designed, built, and tested experimentally in a thermal–vacuum chamber. The experimental results were then used to validate a numerical model, developed using commercial software Simcenter FloEFD. The results showed good agreement between measured and predicted temperature evolution in critical locations of the unit. The model predictions were further improved by conducting analysis of uncertain input data, model settings, and by inclusion of the effect of natural convection in the PCM. The improved model showed better agreement between the model predictions and experiments. The comparison showed that the maximum difference between the measured and calculated temperature at the most important location (the heater) was 1.6 °C and difference of the peak values was 0.8 °C. Finally, the model was used to compare the constructed module containing the PCM with a system consisting of an aluminum block of the same volume as PCM. The comparison showed that the use of PCM allows for a reduction of the maximum temperature by 6.2 °C while reducing the mass almost 3.5 times. The results demonstrate that the developed numerical model allows for accurate predictions of temperature distributions in the designed device, and can be effectively used to design PCM modules dedicated to in-space electronics, thereby increasing their peak capabilities and lifetime.

Thermo-hydraulic performance evaluation of lattice structures with triply periodic minimal surfaces for latent heat storage devices

Triply periodic minimal surface (TPMS) structures exhibit significant potential in latent heat storage (LHS) applications. In this study, numerical investigations were conducted to study the thermal storage performance of four TPMS lattice types: Primitive, IWP, FRD, and Gyroid lattices, used as metallic skeletons in LHS devices. The volumes of both the TPMS skeletons and the phase change material (PCM) were kept constant, with PCM embedded either inside or outside the lattices. The melting process of PCM, the heat storage energy density, and the power density of the LHS units for different configurations were examined. Additionally, a performance evaluation coefficient was introduced to assess the heat transfer and flow characteristics of heat transfer fluid (HTF) flowing on both sides of the lattices. The results indicated that when using Primitive and FRD lattices, embedding the PCM within the internal space of the lattices resulted in a 20 % and 9.8 % higher energy storage compared to embedding it outside the lattices. The internal space of IWP and Gyroid lattices was more suitable for HTF flow channels, resulting in performance evaluation coefficients (PECs) that improved by 27.7 % and 86.3 %, respectively, when HTF flowed through the internal channels of these lattices. Moreover, the Gyroid lattice exhibited the most balanced overall heat transfer performance due to its minimal flow resistance, whereas the FRD lattice had the lowest flow performance due to its complex structure. Therefore, the Primitive and Gyroid lattices could be considered as new heat transfer structures for LHS devices, while the FRD lattice was more suitable for replacing traditional fin structures in heat sink devices.

Enhancing solar flat plate collector efficiency with advanced phase change materials and expanded boron nitride

ABSTRACT Thermal energy storage, particularly through Phase Change Materials (PCMs), is gaining significant attention for its ability to enhance storage capacity and thermal conductivity. PCMs help alleviate the strain on renewable energy sources and stabilize load fluctuations. This study integrates a novel combination of LiNO3-NaSO4·10H2O-NaCl with boron nitride into Flat Plate Collectors (FPCs) to boost system performance. This Composite Phase Change Material (CPCM) increases latent heat value by up to 245.80 kJ, enhancing thermal decomposition and absorption rates while reducing heat losses. Boron nitride improves thermal conductivity by 25%, from 1.378 W/m·K to 5.543 W/m·K, increasing the CPCM's charging rate. The specific heat capacity rises from 4.2 J/g·°C to 5 J/g·°C at a maximum temperature of 90°C. As a result, the collector's efficiency improves by 15%, achieving an overall system efficiency of 88%. Water serves as the heat transfer fluid, and simulations are conducted using Python in Anaconda Jupyter Notebook.

Preparation and thermal stability research of oxalic acid dihydrate-glutaric acid/PAMPS phase change gel for solar thermal energy utilization

Thermal energy storage technology based on phase change materials (PCMs) can address the temporal and spatial mismatches in solar thermal energy conversion, thereby enhancing solar energy utilization efficiency. However, the liquid flow and poor thermal reliability of PCMs limit their large-scale application in solar thermal systems. In this study, we employ a simple “one-pot method” to prepare a form-stable and thermally reliable oxalic acid dihydrate-glutaric acid/poly 2-Acrylamido-2-methyl-1-propanesulfonic acid (OAD-GA/PAMPS) phase change gel. The OAD-GA/PAMPS phase change gel melts at 64.5 °C with a phase change enthalpy of 193.6 kJ/kg, the tensile strength is 7.707 MPa, and the compressive strength is 16.940 MPa. By incorporating 5 wt% BN particles, the thermal conductivity of OAD-GA/PAMPS phase change gel reaches 0.63 W/(m·K). After 200 heating-cooling cycles, the phase change temperature of the OAD-GA/PAMPS phase change gel remains nearly unchanged, and the phase change enthalpy decreases by only 5.7 %. The photo-thermal conversion efficiency of the OAD-GA/PAMPS phase change gel is 82.7 %. The high thermal reliability and photo-thermal conversion efficiency of the OAD-GA/PAMPS phase change gel makes it suitable for solar thermal energy storage applications.

A new approach for enhancing the effectiveness of a regenerative heat exchanger by using organic and inorganic phase change material

A new approach for enhancing the effectiveness of a regenerative heat exchanger by using organic and inorganic phase change material

Optimizing of partial porous structure for efficient heat transfer and thermal energy storage of phase change material in a rectangular cavity

Optimizing of partial porous structure for efficient heat transfer and thermal energy storage of phase change material in a rectangular cavity

Innovative materials integrated with PCM for enhancing photovoltaic panel efficiency: An experimental investigation

The electrical power generated by a photovoltaic panel is crucial due to the high demand for electricity. Operating temperatures above the Standard Test Conditions (STC) negatively impact the output power, which is a significant drawback of this technology. Therefore, it is essential to keep the front and back surface temperatures of the photovoltaic panel as low as possible. Phase Change Material (PCM) is a good passive cooling method, but it has low thermal conductivity. This paper introduces a novel material to address this issue. Iron Filling Waste (IFW) is integrated with PCM to cool the photovoltaic panel. This investigation is presented experimentally with three modules. The highest surface temperature of the reference panel, 78 °C, is recorded for the uncooled module, while with PCM- IFW is 70.5 °C. The comparative analysis shows that the PV module cooled by PCM-IFW achieved an efficiency enhancement and power output increase of 39 % and 33 % respectively, compared to the reference panel without cooling. IFW-PCM achieves an average enhancement in efficiency and output power by 23 % and 11 %, respectively, compared with panels that use PCM only. Also, IFW enhances thermal conductivity without any additional economic cost for the cooling systems.

Incorporation of Phase Change Materials in Buildings

This review paper explores the integration of phase change materials (PCMs) in building insulation systems to enhance energy efficiency and thermal comfort. Through an extensive analysis of existing literature, the thermal performance of PCM-enhanced building envelopes is evaluated under diverse environmental conditions. This review highlights that PCMs effectively moderate indoor temperatures by absorbing and releasing heat during phase transitions, maintaining a stable indoor climate. This paper also delves into the detailed concepts of PCMs, including their classification and various applications within building insulation. It is noted that different types of PCMs have unique thermal properties and potential uses, which can be tailored to specific building requirements and climatic conditions. Furthermore, cost–benefit and environmental assessments presented in the reviewed studies suggest that incorporating PCMs into building materials offers significant potential for reducing energy consumption and mitigating environmental impacts. These assessments indicate that PCMs can lead to substantial energy savings by decreasing the reliance on heating and cooling systems, thereby lowering overall energy costs and carbon emissions. However, despite the promising outlook, this review identifies a need for further research to optimize PCM formulations and integration methods. This optimization is essential for overcoming current challenges and facilitating the widespread adoption of PCMs in the construction industry. Addressing issues such as long-term durability, compatibility with existing building materials, and cost-effectiveness will be crucial for maximizing the benefits of PCMs in enhancing energy efficiency and sustainability in buildings. Overall, this review underscores the transformative potential of PCMs in building insulation practices. By providing a comprehensive overview of PCM classifications, applications, and their impacts on energy efficiency and environmental sustainability, this paper lays the groundwork for future advancements and research directions in the field of PCM-enhanced building technologies.

Development of novel multifunctional phase change microcapsules for improving thermal comfort and radiation properties

Microencapsulated phase change materials (MPCMs) have gained widespread application in energy-efficient buildings, aiming to improve thermal comfort and reduce energy consumption. To enhance the engineering feasibility of MPCMs, researchers are now focusing on developing MPCMs with multifunctional properties, beyond single thermal storage functionality. In this study, we proposed a novel and straightforward approach to fabricate multifunctional MPCMs with BaCO3 as shell and a core composed of binary phase change materials (PCMs) and lipophilic-modified graphite (MG) via self-assembly method. The incorporation of BaCO3 shell provides MPCMs with additional resistance to ionizing radiation pollution due to the high atomic number element Ba. Additionally, the incorporation of MG into PCMs enhances its temperature sensitivity. The thermal analysis indicates that the binary PCMs’ composition in MPCMs results in two phase transition temperatures at 3.3 °C and 26.4 °C, making them capable of thermal storage in line with comfortable residential temperatures across different seasons. Furthermore, MPCMs were introduced into cement paste (CPM) and used to construct cement chambers. Adding 10 wt% MPCMs in the CPM chambers placed outdoors in Wuhan (from June 7th to June 9th) led to a 23.8 % decrease in temperature fluctuations compared to the reference sample. Radiation shielding results indicated that the linear attenuation coefficient (μ) of CPM increased by 58.7 %, due to enhanced incoherent scattering and photoelectric effects between high atomic number elements and photons. Additionally, XCOM simulations predicted a strong correlation between MPCM content and μ values, with particularly high accuracy at low photon energies. Overall, the multifunctional MPCMs developed in this study not only offers a new route for reducing residential energy consumption and shielding ionizing pollution, but also broadens the applicability of traditional PCMs in the building and other fields.

Thermal management optimization strategy for lithium-ion battery based on phase change material and fractal fin

In order to solve the problem of temperature control of lithium-ion battery (LB) in electric vehicles, a new battery thermal management system (BTMS) based on phase change material (PCM) coupled fractal fin (FF) was proposed. The effects of latent heat, thickness, and thermal conductivity of PCM (paraffin) on the thermal properties of BTMS were investigated. Subsequently, the fin structure was added to the BTMS to improve the heat transfer capacity, and the number of fins, aspect ratio, material and structure morphology were explored. The results show that when the latent heat of PCM is 200 kJ/kg, the thickness is 2 cm, and the thermal conductivity is 0.8 W/(m·K), the temperature of LB is 34.9 K lower than that of LB without the BTMS at 4C. In addition, the BTMS has the best performance when FF-II with a fin count of 5, aspect ratio of 7:1, and material of carbon steel are used. The temperatures of LB are 301.8 K, 303.9 K, 305.4 K, and 307.3 K at 1 to 4C, respectively, and the temperature difference in BTMS can be controlled within 2.5 K. This study provides some guidance for the optimization of BTMS.

Flexibility, malleability, and high mechanical strength phase change composite films for solar-thermal and electro-thermal energy storage

Phase change materials (PCMs) are widely used in a range of energy storage applications due to high latent heat absorption and release capacities during phase change processes. There is still a lot to be done to resolve the inherent leakage, stiffness problems, and poor solar-thermal and electrical-thermal conversion capacities of PCMs to functionalize them. Here, a novel solid-solid phase change material (IGPCM) is created using block copolymerization. The IGPCM has a tunable enthalpy (from 58.16 to 99.60 J g−1) by adjusting the molecular weight of the PEG. The obtained IGPCM10K has high toughness (479.1 MJ/m3), excellent bending and malleability. Since IGPCM10K suffers from poor thermal conductivity, photo responsiveness, and electro-thermal conversion, carbon nanotubes (CNT) can be added to our IGPCM10K in a simple way to improve these issues. The thermal conductivity of IGPCM10K-CNT-3 is improved by 55.6 % compared to IGPCM10K. The photothermal conversion efficiency is 84.9 % at 300 mW/cm2. The electrothermal conversion efficiency is 82.3 % at 12 A. The prepared flexible PCM composites have super toughness, high enthalpy, excellent thermal conductivity, and photo-thermal and electro-thermal conversion capabilities, which will show great potential in future applications.

Techno-economic optimization and feasibility of PCM-based seasonal thermal energy storage systems for district heating and cooling

Phase change materials (PCM) are an attractive seasonal thermal energy storage solution for load shifting due to relatively high energy density. Nevertheless, the choice of the right design parameters, such as storage size and phase-change temperature, is nontrivial, as these are tightly linked to the expected seasonal operation of the storage. This paper presents a combined design and operation optimization framework for sizing PCM-based seasonal thermal storage, which can capture dynamic behaviour of the storage in sensible and latent phases, and its impact on the efficiency of connected heat pumps and chillers. The proposed method, formulated as a mixed integer quadratically-constrained programming problem, was applied to a case study of heating-dominated district. It was found that the optimal PCM melting temperature equals to the heating demand supply temperature, thus removing the need of a heat pump to discharge the storage. The optimal operation of storage requires a full charging and discharging cycle of both latent and liquid phase. Higher CO2 emission price does not lead to a significant reduction of CO2 emissions, but the storage size does, leading to a higher heating coverage ratio of the storage, and consequently CO2 emissions and cost savings, which can be further enhanced with PV integration. The economic analysis indicates that, unless other benefits such as storage volume reduction are accounted for, PCM cost should drop by a factor 4 to make this solution economically viable for seasonal storage.

The innovative application of phase change materials in heat storage products: warmer pads

As the issue of energy shortage becomes increasingly severe, energy storage technology has gradually attracted global attention, with the application of phase change materials (PCMs) being particularly widespread. This paper focuses on a common daily product: the warmer pad, and investigates the selection and ratio of suitable PCMs to achieve a recyclable heat storage solution. The study first outlines the research background, significance, and methods, then summarizes the basic principles of phase change and the role of differential scanning calorimetry (DSC) in the study of phase change heat storage. Finally, the properties of PCMs with different proportions were tested, and the DSC curves were analyzed. The results showed that the phase change material mixture with a ratio of paraffin: OBC: expanded graphite = 77:20:3 exhibits excellent performance in heat storage, with a thermal conductivity of 0.547 W/mK, a phase change latent heat of 150 J/g, and a phase change temperature of 41.9C. The warmer pad achieved a surface temperature close to 40C and a heat release duration of nearly one hour. This study aims to promote the industry's transformation towards sustainable development and provide a reference for research in the field of daily-use products with phase change heat storage.

Sea urchin-like Fe3O4 hollow microspheres/fatty amines composites phase change materials for highly efficient light-to-thermal conversion and heat storage

Pure phase change materials (PCMs) have limited photothermal conversion capabilities. To improve the photothermal conversion capability of PCMs, we developed composite phase change materials (FHS@PCMs) of sea urchin-like Fe3O4 hollow spheres (FHS) loaded with fatty amines (hexadecylamine (HDA) and octadecylamine (ODA)). The material composition and the surface nano-raised structure of FHS enable FHS@PCMs to exhibit excellent light absorption (up to 90 %, without any additional modification) and thermal conductivity. Moreover, the internal hollow spherical structure would prevent the leakage of PCM during the phase change process. Interestingly, FHS and FHS@PCMs exhibit inherent superhydrophobic properties with a water contact angle greater than 150°, thus endowing them with self-cleaning properties. FHS possesses strong magnetic properties that aid in material collection. Furthermore, the prepared FHS@PCMs exhibited exceptional thermal properties. The latent heat of FHS@HDA and FHS@ODA was 139.21 J∙g−1 and 140.13 J∙g−1, respectively. Additionally, FHS@PCMs maintained their excellent thermal properties even after 50 and 100 thermal cycles. Under one solar radiation, FHS@PCMs show a photothermal conversion efficiency of 89.63 % and 88.02 %, respectively. Taking of these advantages, the as-prepared composite phase change material may have significant potential in the fields of solar energy conversion and storage.