Organic Phase Change Materials Research Articles

Multi-Faceted Analysis of Phase-Change Composite Intended for Autonomous Buildings

This paper presents the long-term, holistic results of research into an innovative heat accumulator based on an organic phase-change material in the form of a mixture of aliphatic alkanes, molecular silica sieves, carbon recyclate and epoxy and cement matrices. The research included chemical testing of vacuum soaking of molecular silica sieves with a liquid phase-change material. The results proved an improvement in the heat storage efficiency of the heat accumulators due to the addition of carbon recyclate by 28%, while increasing the heat storage time by 134 min, and a reduction in PCM leakage due to the use of molecular silica sieves. In addition to its cognitive scientific value, another research objective of the work achieved was to obtain response functions in the form of approximating polynomials. They provide a useful, validated and verified tool to predict the physical and chemical characteristics of heat accumulators with different contents of individual components. As part of the ongoing research, technical problems related to leak-proofing assurance and matrix selection for organic phase-change materials were also solved. The solution presented is in line with the issues of efficient use of renewable energy, low-carbon and energy-efficient circular economy.

Phase change-related thermal property characterization and enhancement in carbon-based organic phase change composites

By utilizing the significant amount of energy absorbed and released during their phase transitions, phase change materials (PCMs) can capture and store thermal energy to fill gaps between supply and demand. Due to their many favorable properties, organic PCMs have gained attention in a wide range of applications. Nevertheless, their inherent low thermal conductivity has limited the direct use of organic PCMs in thermal energy storage (TES). Extensive research has been conducted on enhancing organic PCM thermal conductivity by incorporating high thermal conductivity materials. Owing to their high thermal conductivity and low density, carbon-based materials have been extensively used for thermal conductivity enhancement in phase change composites (PCCs). Carbon-based organic PCCs, which incorporate highly thermally conductive carbon allotropes and their direct chemical derivatives with organic PCMs, are a group of diverse PCCs with highly promising potential for TES applications. Adequate latent heat and shape stability performances are crucial to the success of the applicational performances of these PCCs. Much empirical research has pushed efforts to enhance these phase change properties, yet a logical understanding of these enhancement efforts based on the thermodynamics and intermolecular interactions of carbon-based organic PCCs has been elusive. In particular, the effect of characterization methods on the evaluation of phase change properties has been largely understudied. This review strives to provide novel physical and chemical insights into latent heat and shape stabilization evaluation processes and enhancement efforts in carbon-based organic PCCs through a detailed review and analysis of recent literature. The review provides an unprecedented comprehension of newly developed PCCs that challenge the traditional understanding that the latent heat of PCCs cannot exceed that of its base PCM. Efforts on phase change property enhancement driven by these new insights have the potential for carbon-based organic PCCs to succeed in a variety of TES applications, including solar-thermal harvesting, thermal management of batteries and electronics, thermoregulating textiles, and infrared stealth and infrared responsive materials.

Thermal stability of organic Phase Change Materials (PCMs) by accelerated thermal cycling technique

Phase change materials (PCMs) can improve thermal comfort of occupants acting as thermal energy storage systems. During their service life, PCMs undergo many phase change transitions. However, there is a lack of feasible and cost-effective techniques to evaluate the effect of thermal cycling on the long-term stability and performance of PCMs, which can influence their selection and restrict a broader acceptance of these materials by the construction sector. This study developed a novel accelerated thermal cycling multi-technique to assess the stability and reliability of PCMs under dynamic thermal conditions. All investigated PCMs showed remarkable stability in terms of phase change temperature and latent heat energy even after undergoing 10,000 thermal cycles. The Thermogravimetric Analysis (TGA) results underscore the suitability of these PCMs for built environments, with minimal mass loss at lower temperatures (below 150 °C). The Fourier Transform Infrared spectroscopy (FT-IR) and 1H Nuclear Magnetic Resonance (NMR) results revelled no molecular changes induced by thermal cycling. The novel accelerated thermal cycling technique provides more accurate results than thermal cycling using Differential Scanning Calorimetry (DSC) only, overcoming the issues of contamination and subcooling of smaller samples in DSC measurements.

Comparative Investigation of Thermal Properties Improvement of Nano-Enhanced Organic Phase Change Materials

Thermal energy storage (TES) using phase change materials (PCMs) is one of the potential solutions for stockpiling thermal energy and utilizing it for different applications, which results in effective energy usage. The main drawback of organic PCMs in practical applications is poor heat transfer due to low thermal conductivity (TC). Therefore, investigations into nano-enhanced PCMs are being explored to improve their thermophysical properties. In this work, the various thermophysical characteristics of nano-enhanced lauryl alcohol as a PCM were investigated using carbon-based and metallic nanoparticles. The results indicated that the addition of nanoparticles improved its thermal properties and affected other physical properties, such as viscosity. The latent heat was degraded with the addition of nanoparticles. The results revealed that by adding MWCNTs and CuO nanoparticles, a maximum of 82.6% and 49.6% improvement in TC was achieved, respectively. The maximum drop in latent heat during melting and freezing for the PCM with MWCNTs was about 10.1% and 9.3%, respectively, whereas for the PCM with CuO, they were about 11% and 10.3%, respectively. The lowest supercooling for the PCM with MWCNTs and CuO nanoparticles was 8.6 and 8.3 °C, respectively. The present work confirms that nano-enhanced PCMs can be a potential material for storing thermal energy for various applications.

Development and preparation of novel nano-enhanced organic eutectic phase change materials for low-temperature solar thermal applications

ABSTRACT Thermally reliable and stable eco-friendly Phase change materials are of significant aid in thermal energy storage technology, leading to improved energy utilization and reliability of the system. This study develops two novel organic eutectic PCM of Lauric acid – Margaric acid (LM) and Myristic acid – Margaric acid (MM), which are chemically stable and thermally compatible for latent heat energy storage. LM eutectic mixture had a melting temperature of 52.66°C with a latent heat of 163.68 J/g, and MM eutectic mixture had its melting temperature at 44.79°C and a latent heat of 197.31 J/g. The phase change temperatures were favorable for low temperature solar thermal applications with good latent heat capacity. The thermal characteristics of these eutectic mixtures are further enhanced with the dispersion of highly conductive Multi walled carbon nanotubes (MWCNT) at three different mass fractions (.5%, 1% and 1.5% by weight). Nano enhancement could achieve exceptional thermal conductivity enhancement in MM eutectic mixture by 110.6% and 83.73% in LM eutectic mixture. Thermogravimetric analysis and Fourier-transform infrared spectroscopy analysis ensured the thermal and chemical stability of the eutectic mixtures. The optical absorption characteristics were extensively enhanced with nano particle addition, which is highly preferable in solar thermal applications.

Thermophysical characterization and reliability analysis of binary composite nano doping on stearic acid-acetamide eutectic PCM

Organic phase change materials (PCM) have been extensively studied and employed for thermal energy storage applications, especially in the last decade. Wide range of melting temperature with high latent heat of fusion and absence of super cooling have made them highly desirable for energy storage applications, yet their intrinsic low thermal conductivity has been a major drawback in practical implementation. This study intends to address this and study the thermophysical characteristics of an organic PCM through composite nano doping. Stearic acid-acetamide eutectic PCM with a melting temperature of 65.73 °C and a latent heat of 203.72 J/g, was incorporated with a binary blend of Aluminum Oxide nanoparticles and multi-walled carbon nanotubes (MWCNT). The addition of metallic oxide and carbonaceous nanoparticles increased the melting temperature of the eutectic mixture by 2.9 °C and a highly advantageous increment in latent heat of fusion by 10% was observed, due to the improved molecular interaction introduced by the nanoparticles. Composite nano doping enhanced the thermal conductivity of the eutectic PCM by a 132.7% and also resulted in high optical absorption properties. The prepared eutectic mixtures were chemically stable and the eutectic PCM showed an improved final degradation temperature and thermal stability, with composite nano doping. Thermal reliability was analyzed through accelerated thermal cycling test and the eutectic mixtures could retain their thermal characteristics and chemical stability even after 500 thermal cycles. Composite nano doping proved to be a reliable thermophysical characteristics enhancement technique for organic eutectic PCM.

Solar photovoltaic-assisted DC vapour compression with a low-cost ice gel thermal battery for off-grid building cooling

In off-grid areas where extending the grid is costly, traditional AC powered air conditioning units pose challenges for off-grid photovoltaic PV setups due to expensive inverters and battery storage. This leads to an interest in cost-effective solar-driven DC cooling system. However, its efficiency depends on solar energy availability with limited operation during low solar radiation. This study proposes a solar PV-driven DC vapour compression system with variable refrigerant flow (VRF) and low-cost organic phase change material (PCM) ice gel storage. Preliminary experimental work determined the best operational mode namely, Mode A (PV + Thermal Battery), Mode B (PV-electrical battery-3h + Thermal Battery), Mode C (PV-grid + Thermal Battery), and Mode D (Grid + Thermal Battery). Key performance parameters include the Performance Quality Factor of the PV-powered system SFPVVC, and levelized cost of cooling (LCOC). Mode B was found the best, and due to the system's complex dynamic variation with environmental parameters, a novel simulation approach combining artificial neural network (ANN) and TRNSYS was developed and experimentally validated. Thermal comfort is crucial for healthcare facilities as it promotes patient well-being, enhances staff performance, and is vital for infection control, thus a rural healthcare facility in Malaysia was selected for the simulation case-study. Mode B showed at least 50 % higher SFPVVC compared to grid reliance, with superior LCOC performance, ensuring sustainable cooling despite limited electricity supply. The low-cost ice gel thermal battery reduced the system cost to 0.06 USD/kWh compared to 0.56 USD/kWh without it and 1.01 USD/kWh with grid extension. These findings offer insights for implementing similar sustainable cooling systems in rural areas.

Antileakage performance of Schiff base-reinforced thermal energy storage wood for indoor temperature control

Thermal energy storage wood has been rapidly developed as a green and renewable energy-saving building material. In this study, bio-based Schiff bases (VF) were prepared from vanillin and furfurylamine via aldehyde–amine condensation and used as a small molecule fixative. Subsequently, VF and dodecylamine were mixed uniformly and impregnated into rubberwood under pressure, affording thermal energy storage wood (TESW-x%VF). The results revealed that TESW-x%VF exhibited adjustable enthalpy (41.67–88.23 J g−1) and room-temperature phase transition (25°C–27°C). Moreover, the addition of VF improved the antileakage performance of TESW. According to density functional theory calculations, this is because the adsorption energy between VF and dodecylamine molecules has increased by 3–8 times compared to dodecylamine molecules. The above results provide a solution for the leakage issue associated with organic phase-change materials and aid in the future development of energy-saving wood building materials, which also improves the high-value utilization of chemical components in agricultural and forestry crops.

Stable and reliable PEG/TiO2 phase change composite with enhanced thermal conductivity based on a facile sol-gel method without deionized water

Some shortcomings exist in organic phase change materials, including leakage susceptibility, low thermal conductivity, and preparation complexity. Herein, polyethylene glycol/titanium dioxide shape-stabilized composite phase change material (PEG/TiO2 ss-CPCM) was fabricated by facile sol-gel method without deionized water using tetrabutyl titanate (TBOT) as precursor. In this composite, not adding deionized water prolonged the gelation time, allowing PEG to bind as much TiO2 as possible and enhancing energy storage capability; TiO2 acted as the supporting framework to maintain the material's shape stability and enhance thermal conductivity. The melting and crystallization phase change enthalpies of prepared PEG/TiO2 ss-CPCM were 128.3 J/g and 113.1 J/g with an encapsulation efficiency of 74.14 % when PEG: TBOT = 1.5: 1. After repeating 300 thermal cycles, the phase change enthalpy remained almost constant. Besides, the thermal conductivity of PEG/TiO2 ss-CPCM was 1.22 times that of PEG, and the potential for thermal management applications. The advantages (energy storage capability, shape stability in thermal environments, thermal reliability, and thermal management) of the PEG/TiO2 ss-CPCM prepared by facile synthesis, not only propose a phase change material with excellent thermal properties and shape stabilization but provide a green and feasible strategy for the fabrication of PEG/TiO2 composite phase change materials utilizing the sol-gel method.

Utilizing Ragone framework for optimized phase change material-based heat sink design in electronic cooling applications

This study explores the latent thermal energy storage potential of an organic phase change material with porous copper foam and its applicability in electronic cooling under varying heat load conditions. The organic phase change material, n-eicosane, is known for its inherently low thermal conductivity of 0.15 W/mK, rendering it vulnerable during power spikes despite its abundant latent heat energy for phase transition from solid to liquid. Porous copper foams are often integrated into n-eicosane to enhance the composite's thermal conductivity. However, the volume fraction of the phase change material in the porous foam that optimally improves the thermal performance can be dependent on the boundary condition, the cut-off temperature, and the thickness. A finite difference numerical model was developed and utilized to ascertain the energy consumption for the composite of n-eicosane with two kinds of porous copper foam with varying porosity under different heat rates, cut-off temperatures, and thickness. In addition, the results are compared with a metallic phase change material (gallium), a material chosen with a similar melting point but significantly high thermal conductivity and volumetric latent heat. For validation of the numerical model and to experimentally verify the effect of boundary condition (heat rate), experimental investigation was performed for n-eicosane and high porosity copper foam composite at varying heat rates to observe its melting and solidification behaviors during continuous operation until a cut-off temperature of 70 °C is reached. Experiments reveal that heat rate influences the amount of latent energy storage capability until a cutoff temperature is reached. For broad comparison, the numerical model was used to obtain the accessed energy and power density and generate thermal Ragone plots to compare and characterize pure gallium and n-eicosane - porous foam composite with varying volume fractions, cutoff temperature, and thickness under volumetric and gravimetric constraints. Overall, the proposed framework in the form of thermal Ragone plots effectively delineates the optimal points for various combinations of heat rate, cut-off point, and aspect ratio, affirming its utility for comprehensive design guidelines for PCM-based composites for electronic cooling applications

Evolving Thermal Energy Storage Using Hybrid Nanoparticle: An Experimental Investigation on Salt Hydrate Phase Change Materials for Greener Future

Thermal energy storage (TES) assisted with phase change materials (PCM)s seeks greater attention to bridge the gap between energy demand and supply. PCM has its footprint toward efficient storage of solar energy. Inorganic salt hydrate PCMs are propitious over organic PCMs in terms of energy storage ability, thermal conductivity, and fireproof, however the major issue of supercooling and poor optical absorbance remains. This research investigates commercialized inorganic salt hydrate PCM with phase transition temperature of 50 °C, thermal conductivity of 0.593 W m−1 K which is favoured with melting enthalpy of 190 J g−1, and 2–3 °C of supercooling. Mixture of graphene: silver at a proportion of (1:1) is used as the hybrid nanomaterial to further enhance the thermal conductivity, optical absorbance, and thermal stability. Hybrid nanocomposites are developed via two‐step process involving direct mixing and ultrasonication. Morphological behaviour, chemical stability, optical property, thermal property, thermal reliability, and stability of the developed nanocomposite samples are experimentally analysed. As a result, sustainable TES materials with thermal conductivity of 0.937 W m−1 K, optical absorbance of 0.8, increased energy storage potential is formulated. Subsequently a numerical simulation is conducted to illustrate the potential of the developed nanocomposite in transfer of heat energy.

Energy storage, thermal-hydraulic, and thermodynamic characteristics of a latent thermal energy storage system with 180-degree bifurcated fractal fins

The low thermal conductivity of organic phase change materials limits the performance of latent thermal energy storage (TES) systems. Inspired by fractal theory, this study proposes an innovative 180° fractal fin for enhancing the thermal performance of latent TES systems. The effects of length ratios (l) and fractal levels (N) are numerically investigated employing the enthalpy-porosity method. Compared with traditional rectangular fins, the results indicate that the 180° fractal fins reduce the integral average value of the maximum velocity by 2.24%–48.51%, which indicates the suppression of natural convection by the latter. Increasing l and N result in a general increase in melting time. Compared to the TES systems without fins and with rectangular fins, the 180° fractal fins can respectively reduce melting time by up to 88.79% and 28.00%, increase integral average Nusselt number by up to 7.30 times and 34.21%, and enhance energy storage power by a maximum of 8.55 times and 38.71%. Moreover, flow viscous entropy generation can be neglected compared to thermal entropy generation. In contrast to rectangular fins, the employment of fractal fins leads to a maximum reduction of 90.06% and 99.10% in total frictional entropy generation and thermal entropy generation, respectively.

Multidimensional Data Encoding Based on Multicolor Microencapsulated Thermoresponsive Fluorescent Phase Change Materials

AbstractLuminescent materials are emerging promising tools for digital data encoding due to their reduced cost, facile reading, robustness, and durability. For this, the use of fluorescent systems that combine multicolor emission with sensitivity to external stimuli will be highly desirable, as they can offer rewritable data encoding together with enhanced encryption security and storage density. Herein a novel strategy is pioneered to reach this goal, which exploits the temperature‐responsive emission properties of the mixtures of regular fluorophores with simple organic phase change materials (PCMs) such as paraffins. By preparing a diversity of microcapsules of these mixtures comprising different dyes and PCMs, thermosensitive fluorescent pixels can be prepared in a low‐cost, straightforward, and scalable manner that exhibits multicolor dynamic emission behavior. These features are capitalized to fabricate pixel arrays that perform two advanced digital encoding operations: high‐security 3D information encryption, and 4D data storage.

Indium-Mediated Acyloxyallylation-Based Synthesis of Galacto-Configured Higher-Carbon Sugar Alcohols as Potential Phase Change Materials.

Sugar alcohols fulfilling specific structural requirements are a substance class with great potential as organic phase change materials (PCMs). Within this work, we demonstrate the indium-mediated acyloxyallylation (IMA) as a useful strategy for the synthesis of higher-carbon sugar alcohols of the galacto-family featuring all hydroxyl groups in a 1,3-anti-relationship with three major synthetic achievements: first, the dihydroxylation of the IMA-derived allylic sugar derivates was systematically studied in terms of diastereoselectivity, revealing a high degree of substrate control toward anti-addition. Second, we demonstrated the use of a "double Mitsunobu" reaction, inverting the stereochemistry of terminal diols. Third, the IMA toolbox was expanded to accomplish the synthesis of derivatives with up to 10 carbon atoms from particularly unreactive aldoses. Thermal investigations of all synthesized sugar alcohols, including examples with exclusive 1,3-anti- and suboptimal 1,3-syn-relationships as well as even and odd numbers of carbon atoms, were performed. We observed clear trends in melting points and thermal storage densities and discovered limitations of organic substances in this class with melting points above 240 °C as PCMs in terms of thermal stability. With our study, we provide insights into the dependence of thermal properties on structural features, thus contributing to further understanding of organic PCMs for thermal energy storage applications.

Application of Soy Wax Phase Change Material as Thermal Energy Storage in Wall Building

High solar radiation in the tropics area buildings and inappropriate selection of building materials cause an increase in room temperature which interferes with thermal comfort. This study aims to reduce the absorption of heat received in the building with the modification of building walls by adding Phase Change Material (PCM) as Thermal Energy Storage (TES). Soy wax is an organic PCM that is abundant in Indonesia, cheap, and has a melting point of 43.92°C and a freezing point of 38.49°C, which are the range of solar heat radiation in buildings. The application of soy wax on the walls of the building is carried out using a prototype room 80x105x60 cm made of Plywood with a 1 cm thickness of soy wax in the middle of the wall. The test was carried out by comparing the prototype without and with a layer of soy wax pack on the wall. Based on the tests carried out for 24 hours, it was found that the addition of soy wax on the prototype wall can decrease the room temperature to 37°C from 41°C during the day. The use of soy wax can absorb the heat received by the building by 10% at peak load and has a small heat transfer rate of 15.56 W so the heat transferred into the room is small. Soy wax walls function as insulators on the walls and can withstand heat absorbed from outside the building so that it is not completely transferred into the room.

Bidirectional anisotropic bacterial cellulose/polyvinyl alcohol/MXene aerogel phase change composites for photothermal conversion enhancement

The issues of inherent low thermal conductivity, slow heat transport rate and easy leakage are critical challenges for accelerating solar-thermal energy harvesting and storage for organic solid-liquid phase change materials (PCMs). Aerogel carriers with thermal conductivity enhancement based on ice temple methods show favorable potential for PCMs solar thermal applications. Comparing with disordered and unidirectional freezing, bidirectional freezing can assemble efficiently in multiple dimensions and result in long-range ordered structures. In this paper, bacterial cellulose/polyvinyl alcohol/MXene aerogels were constructed by bidirectional freezing. The anisotropic PCMs composites were from vacuum impregnation PEG into aerogel networks. By controlling crystallization and growth of ice crystals through the dual temperature gradients, the PCMs composites obtained enhanced heat transfer efficiency in horizontal and vertical directions. Bidirectional aligned PCMs with PDMS wedge angle of 0° and 20° exhibit high thermal conductivity of 0.716 W m−1 K−1 and 0.768 W m−1 K−1, which were 184% higher than that of PEG, and photothermal conversion efficiency of 55.17% and 76.91%. Remarkably, the PCMs composites with a 20° PDMS wedge angle also exhibited a high PCM loading capacity (96.3%) and a high enthalpy (157.7 J/g). The results show that bidirectional anisotropic PCMs composites have excellent overall performance and are expected to improve solar thermal application.

Encapsulation and functionalization strategies of organic phase change materials in medical applications

Encapsulation and functionalization strategies of organic phase change materials in medical applications

In51Bi32.5Sn16.5@SiO2 microcapsules-based composite phase change materials with high thermal conductivity and heat storage density for electronics thermal management

Combining phase change microcapsules and various matrix materials can construct novel composite phase change materials (CPCMs). These composite materials hold immense potential for electronics thermal management, owing to their adjustable heat storage capacity and stable shape. Most previous studies focus on enhancing the thermal conductivity of CPCMs by adding thermally conductive fillers or modifying the microcapsule shells. Nevertheless, achieving both high thermal conductivity and heat storage density simultaneously remains a challenge. In this paper, low melting point alloy (In51Bi32.5Sn16.5) was introduced as core material of the microcapsule to enhance the thermal conductivity, due to its significantly higher thermal conductivity compared to commonly used organic or inorganic phase change materials (PCMs). In51Bi32.5Sn16.5@SiO2 microcapsule was synthesized through the sol-gel polymerization method. Furtherly, a form-stable CPCMs consisting of the microcapsules and silicone rubber (SR) matrix were prepared for electronics thermal management. The In51Bi32.5Sn16.5@SiO2 microcapsules exhibit an impressive thermal conductivity of 13.49 Wm−1 K−1, acting as a dual-functional filler for thermal storage and thermal conduction enhancement. Hence, the CPCMs possess a significantly enhanced thermal conductivity of 0.45 Wm−1 K−1, representing a remarkable improvement of 350 % compared to that of pure SR. In addition, the phase change heat storage density of the CPCMs was as high as 71.73 J/cm3. Notable, the prepared CPCMs demonstrate exceptional heat dissipation performance, resulting in a remarkable 23 °C reduction in chip temperature when applied for thermal management. This study offers a novel perspective on the preparation of microcapsule-based CPCMs for electronics thermal management.

On the performance of a latent heat thermal storage unit integrated with a helically coiled copper tube and organic phase change materials: A lab-scale experimental study

In this study, the performance of a latent heat thermal storage (LHTS) unit integrated with a helically coiled copper tube and organic phase change materials is investigated using a lab-scale experimental setup. The effects of various operating conditions such as the coil thickness, testing fluid temperature/flow rate, PCM type, turbulator, and stirrer rotational speed on phase change behavior are investigated. The evaluation is based on PCM temperature variations, total heat transfer coefficient, and thermal effectiveness. The effects of testing fluid temperature, PCM type, turbulator, and stirring speed on phase change behavior are found to be more pronounced compared to those of the coil thickness and the fluid volume flow rate. Considering the melting process, it is found that the average temperature of the PCM in the LHTS unit with a turbulator is higher than that of the case without turbulator by nearly 10 °C which indicates an improvement in the heat transfer between water-PCM. The average PCM temperature is found to increase by 2 °C and 3.5 °C when a stirrer with a rotational speed of 200 and 400 rpm is employed, respectively. The total heat transfer coefficient for the LHTS unit at a stirring speed of 400 rpm (200 rpm) shows a significant increase of 39.6% (27%) compared to the scenario without a stirrer.

Acceleration of heat discharge of composite lauric acid using magnetic dopant

Composite phase-change materials (PCMs), consisting of nanoparticle metal or metal oxide suspended in an organic PCM, are considered promising for overcoming the significant drawbacks of organic PCM, particularly their relatively low thermal conductivity. This paper presents an experimental study of the performance of composite PCMs in terms of chemical stability, thermal stability, phase transition temperature, latent heat, thermal conductivity, and viscosity related to freezing characteristics. The composite PCM consists of an organic PCM of lauric acid (LA) and magnetic dopants of Fe3O4 and CoFe2O4 at concentrations of 2, 5, and 10 wt%. The freezing data revealed the time and temperature characteristics related to the beginning of freezing, the end of the solidification process, and the total crystallisation period. For dopant concentrations below 5 wt%, the dopant increased the heat transfer rate and accelerated the solidification process. However, its effectiveness at the highest dopant concentration of 10 wt% was highly dependent on the microstructure of the dopant particles and its effect on viscosity and thermal conductivity. Based on the data analysis, we proposed a maximum dopant concentration of 5 wt% for the optimum performance of the composite LA using a magnetic dopant—dependent on the particle size that determined the interparticle magnetic dipolar interaction. However, compared with previous experimental findings for non-magnetic dopant particles, the composite FA using a magnetic dopant showed a lower thermal conductivity enhancement and lower time savings for solidification.