Nanocomposite Phase Change Materials Research Articles

A study on novel dual-functional photothermal material for high-efficient solar energy harvesting and storage

The solar-heat storage efficiency of devices based on phase change materials (PCMs) is limited due to the light absorption and internal heat transfer within the PCMs, unclear thermal conductivity-enhancement mechanism within nanocomposite PCMs, and uncontrollable photothermal-interface modulation. Therefore, a novel controllable strategy was proposed in this study to fabricate dual-functional photothermal storage three-dimensional (3D) phase change blocks (PCBs) with higher thermal conductivity (27.98 W/m·K) and spectral absorption (98.03%) compared to those of most previously reported PCM-based devices. The as-synthesized PCBs contained millimeter-sized graphite plates with horizontal Van der Waals bonds and oriented micro/nanoscale graphite nanosheets. The structural properties of thin PCM layers between the PCB sheets have synergistically reduced the internal interfacial thermal resistance of the PCBs. Laser-controllable induction was used to fabricate integrated biomimetic-forest 3D optical absorbers on the high thermal conductivity interface of the PCBs, which significantly reduced the thermal resistance of the optical-thermal interface. The resulting 3D-PCBs, integrated with thermoelectric generators, powered portable electronic devices, expanding the applications of traditional PCM heat-storage devices. Therefore, this study will guide the future design of high-performance solar-thermal storage PCMs with a wide range of practical applications.

Synthesis and characterization of myristic acid - infused Al2O3/CuO/MWCNT nanocomposites for energy storage and cooling applications

Phase change materials are highly effective in improving the thermal efficiency of a heat exchanger, making them a choice for enhancing renewable energy to achieve a feasible environment. In this study, myristic acid (MA) was used as a phase change material and aluminium oxide (Al2O3), copper oxide (CuO) of 2.5, 5, 10 wt % and multi-walled carbon nanotubes (MWCNT) of 1.0, 1.5, and 2 wt % were used as the nanoparticles to produce MA-embedded nanocomposite phase change material (NCPCM). The characterization studies, namely x-ray diffraction, Thermal Conductivity, field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA) were performed on nanocomposite phase change materials to ensure their homogeneous distribution and property enhancement of the fabricated samples. In addition, a Computational Fluid Dynamics (CFD) analysis was conducted to assess the impact of NCPCM on the rates of solidification and melting. The field emission scanning electron microscopy analysis confirms the homogeneous distribution of micro/nanoparticles Al2O3, CuO, and MWCNT with MA. From the x-ray diffraction (XRD) analysis, the homogeneous nature of the fabricated NCPCMs was identified. Fourier transform infrared spectroscopy (FTIR) and Raman Spectroscopy results confirmed the absence of new particle formation due to the physical interaction between nanocomposites and myristic acid. The fabricated NCPCM samples were undergone 500 thermal cycles to ensure their thermal reliability. It is evident from the test results that the addition of nanoparticles to base PCM enhances the thermal properties. The thermal performance of 2 wt% MWCNT-embedded MA was superior to that of aluminium oxide and copper oxide. DSC results revealed that the 2 wt% MWCNT added MA possessed the highest variation of 8.6% in its latent heat storage value compared to pure MA and had a significant variation compared to other fabricated NCPCM compositions. Adding 2 wt% MWCNT to MA has increased the thermal conductivity of pure PCM from 0.15 W mK−1 to 0.38 W mK−1.

Thermally enhanced nanocomposite phase change material slurry for solar-thermal energy storage

This paper investigates the photothermal conversion performance of an innovative heat transfer fluid containing nano-encapsulated phase change material (PCM) with metallic shell materials in a solar thermal energy storage system. The influences of shell thickness, core size, shell material type, PCM mass and shell volume concentrations on the thermal performance of the heat storage medium are investigated and compared. The results show that the heat transfer rates of water-based Ag, Au, Cu and Al nanofluids are 6.89, 5.86, 7.05 and 6.99 W, respectively, while slurries formed by adding paraffin@Ag, Au, Cu and Al nano capsules to pure water enhance heat transfer by 6.18, 13.38, 10.8 and 11.33 %, respectively. The metallic nanoparticle-based shell materials further augment the temperature and energy storage gains by enhancing the solar radiation capture capability of the heat storage medium. Specifically, depending on the mass concentration of PCM, the storage capacity of paraffin@Cu slurry is augmented by up to 290 %. As the shell thickness of the Ag particles also decreases from 8 to 2 nm, it augments the slurry's storage ability for thermal energy by 7 %. The enhancement in the dimensions of the nano capsules, however, causes the surface area-to-volume ratio (SA:V) to reduce the photothermal conversion of the slurry by clustering. Therefore, the thermal energy storage behaviour of the Paraffin@Cu slurry is diminished by 5 % as the core size enhances from 10 to 40 nm. Further, the augmentation in the volume concentration of Al particles in the shell surprisingly reduces the thermal energy storage by 5 %. Finally, paraffin-based solid PCM is also experimentally tested for validation of the specific heat capacity model at various wind speeds and solar radiation.

Advancing heat management in proton-exchange membrane fuel cells through hybrid nano-composite phase change materials

Heat management challenges in proton-exchange membrane fuel cells (PEMFC) leads to performance degradation, particularly during operational fluctuations and vehicle downtime. This study examines the use of Nano-additive phase change materials (PCMs) as an innovative approach to thermal management in PEMFCs. It addresses a research gap, as PCMs' advantages in batteries and electronics are well-known, but their application in PEMFCs remained relatively unexplored. Hence, using the ChtMultiRegionFoam solver from OpenFOAM, two heat transfer aspects in PEMFCs are studied. The first examines PEMFC cooling under normal conditions, combining liquid cooling with a hybrid Nano-composite phase change material (HNCPCM). The results indicate the HNCPCM cools the PEMFC for 11 min before reaching saturation, after which liquid cooling starts. Moreover, with HNCPCM, the PEMFC's thermal efficiency and temperature uniformity enhance by 7.04 % and 39.76 %, respectively. Therefore, the HNCPCM contributes to cooling as the temperature and voltage fluctuate under real conditions. The second aspect evaluates PCM and insulation to maintain the PEMFC stack's operating temperature range (OTR) during downtime. Using 4 mm PCM and 11 mm insulation, the stack stays within the OTR for nearly 4 h, extending the OTR duration by 49.2 %. Consequently, the waste energy stored by PCM ensures the stack remains within the OTR, averting performance degradation upon restart.

Experimental study on the performance enhancement of PV/T by adding graphene oxide in paraffin phase change material emulsions

Traditional water-based PV/T systems have low heat storage density, high PV backsheet temperatures, and low energy utilization in practical applications. In this work, nanoparticles were applied to improve thermal conductivity and simultaneously emulsions were added to enhance energy storage density of the conventional heat transfer media. Furthermore, the synergistic effect of nanocomposite Phase Change Material Emulsions (PCME) as the heat transfer medium on the thermoelectric efficiency of PV/T was studied in a real system. Specifically, the water-based 30 % paraffin emulsions with graphene oxide (GO) concentration of 0.01, 0.02 and 0.03 wt% were prepared by ultrasonic stirring and their thermophysical properties were characterized. The results show that the 30 wt% paraffin emulsion with addition of 0.02 wt% GO has the phase change temperature of 35 °C, latent heat of 42.93 J/g, thermal conductivity of 0.505 W/(m·K) and viscosity coefficient of 0.91. It shows the thermal efficiency of the paraffin/GO emulsion increased by 92.28 %, the electrical efficiency increased by 8.87 %, the comprehensive efficiency increased by 45.75 %, and 15.8 % increase in heat collection for the heat exchange tank in comparison with the water. It is concluded application of PCME would improves the thermoelectric performance of the system than traditional water-based PV/T systems.

Phase change material nanocomposites as an internal curing aid for nano-modified concrete under cold weather

Ultrafine nano-silica particles can improve the hydration process and concrete performance due to its high surface area and potent reactivity, which may be utilized to counteract the adverse effects of cold temperatures. In the current study, five nano-modified concrete mixtures were prepared to investigate the effect of a curing freezing temperature (−15 ℃) on their mechanical and physical properties, durability, and microstructure features. All mixtures comprised calcium nitrate-nitrite as a cold weather admixture system (CWAS) to depress the freezing point of mixing water. In addition, nano-silica or nano-clay powders impregnated with phase change material (PCM) were added to the mixtures as internal curing nanocomposites. All mixtures were cured at − 15ºC to simulate winter conditions in cold regions. The mixtures’ performance was assessed based on setting times, 7 and 28 days compressive strengths, fluid absorption, and resistance to frost damage in water and salt solution. Furthermore, thermogravimetry, scanning electron microscopy associated with energy-dispersive X-ray spectroscopy, and mercury intrusion porosimetry were performed to assess the hydration, microstructural development, and pore structure features of the produced concrete, respectively. The coexistence of nano-silica and CWAS with the nanocomposites, especially in the case of nano-silica powder as a host for PCM, markedly improved the overall performance of concrete. This highlights the promising use of nano-modified concrete cured internally with nanocomposites for cold weather construction applications (down to −15 ℃), without the need for heating practices.

Organic/carbon and organic/carbon-metal composite phase change material for thermoelectric generator: Experimental evaluation

Phase change materials (PCMs) are regarded as a promising choice for thermal energy storage and thermal regulation applications owing to their extensive range of operational temperature. Nevertheless, the effective utilization of PCMs is primarily limited by their inadequate thermal conductivity. Present study investigates the efficacy of employing graphene (Gr) mono nanoparticles and graphene-silver (Gr:Ag) hybrid nanoparticles as an approach to enhance thermal features and establish a comparative analysis in energy storage performance of organic phase change material (PCM). The comparative study suggest the addition of 0.8 weight% (wt%) of hybrid Gr:Ag nanoparticles (NPs) enhanced the thermal conductivity of PCM (RT54HC) by 96 %, while 0.8 wt% addition of mono graphene NPs increases thermal conductivity by 83 %. Hybridization of Ag nanoparticle over Gr nanoparticle surface ensures uniform dispersion of nanoparticle into the PCM matrix overcoming the issue of floating in graphene mono nanoparticle and settling in silver nanoparticle. Subsequently, energy storage enthalpy of nanocomposite PCM with 0.8 wt% NPs of Gr and Gr:Ag nanoparticle results in increase in latent heat by 11 % and 8.5 % respectively. Likewise, inclusion of Gr nanoparticles resulted in a decrease in optical transmissibility by 71 %, while Gr:Ag hybrid nanoparticles led to a slightly lower decrease of 65 %. The composites also exhibited a minor alteration in their thermo-physical properties following 500 thermal cycles, thus validating the reliability of prepared nanoparticle enhanced PCMs. Further, hybrid nanocomposite applied in thermoelectric generator (TEG) that produced 425 mV in comparison to base PCM 325 mV. Therefore, the prepared nanocomposites, with their established capabilities, have the potential to make a substantial contribution to the advancement of energy storage requirements in the future.

MXene-based eutectic salt hydrate phase change material for efficient thermal features, corrosion resistance & photo-thermal energy conversion

Salt hydrate phase change materials (PCMs) possess low thermal conductivity, degree of supercooling, lack of corrosion resistance and poor photo thermal conversion ability. To overcome these challenges, a two dimensional, chemically stable, optically & thermally efficient MXene@eutectic salt hydrate composite PCM is developed for effective harnessing of solar energy and thermal energy storage (TES) applications. Low temperature eutectic salt hydrate PCM with phase transition temperature of 27.6 °C and 216 J/g melting enthalpy is developed using sodium sulphate decahydrate (SSD) and sodium phosphate dibasic dodecahydrate (SPDD) based on Schrader equation. Advanced 2D layered material, MXene (Ti3C2) is synthesised from MAX phase (Ti3AlC2). Furthermore, MXene based PCM nanocomposite is developed with binary eutectic PCM of SSD/SPDD at different weight fractions through two step technique. Developed nanocomposite PCM exhibits better chemical stability, high optical absorbance of (1.1), low transmissibility (10.2 %), reliable thermal conductivity (0.621 W/m⋅K), improved melting enthalpy (161.2 J/g) and considerable cycle stability. The optical absorbance and thermal conductivity demonstrated a superior photo-thermal conversion capability and thermal networks for the developed MXene based composite sample at 0.9 wt% of MXene. The above properties are experimentally inferred by evaluating the developed MXene@ eutectic salt hydrate and base eutectic PCM under the solar simulator. The interfacial attraction between the two dimensional MXene nano flakes and the developed eutectic PCM ensures a promising ability to trap solar energy effectively for thermal regulation in a sustainable direction. Subsequently, the effect of MXene with SSD/SPDD in regard to the issue of corrosion is explored for copper and aluminium metal surface.

Thermodynamic and thermal degradation kinetics analysis of coconut shell biomass based phase change material

Phase change materials (PCMs) stores and releases thermal energy in the form of latent heat during phase transition. Though PCMs are durable in nature, they suffer commercial application owing to low thermal conductivity. Inclusion of metal and carbon based nanoparticles are typically adopted to overcome the complication of poor conducting nature of organic PCMs. In this experimental research we develop a bio based nanoparticle using coconut shell in an environmental friendly manner to enhance the thermal conductivity of organic PCM polyethylene glycol 1000. Bio nanoparticle (BNP) improves the thermal conductivity of the developed nanocomposite PCM by 73.1% with 0.9 wt% of coconut shell BNP hence we evaluate the thermodynamic and thermal kinetics parameter of the nanocomposite PCM sample with 0.9 wt% biochar based nanoparticle. In addition the authors have analysed the thermal decomposition kinetics of the optimized PCM composite using Coats and Redfern method to exhibit the reaction mechanism, thermodynamic and kinetic parameter.

Optical performance and chemical stability evaluation of new era phase change material: Activated by hybrid nanoparticle

Inorganic salt hydrate phase change materials (PCMs) are ahead of organic PCMs in terms of energy storage ability and safety as they are non-flammable. However the major hindrance with inorganic PCM are degree of supercooling and low thermal conductivity though better than organic PCM. The common technique to enhance the thermal conductivity is via dispersion of metal and carbon nanoparticle. Though they enhance the thermal conductivity of the nanocomposite, with continuous operation the nanoparticle agglomerate and settles down owing to their density. Henceforth, in the current research work we conduct an experimental investigation to enhance the optical and thermal performance of commercialised inorganic salt hydrate PCM using metal-carbon hybrid nanoparticle. We disperse graphene silver nanoparticle at different weight ratio adopting a two-step method followed by probe sonication to ensure uniform dispersion. We achieve a highly stable nanocomposite with 584% increase in optical absorbance of electromagnetic waves and 86% decrease in transmittance. Thermal management of electronic gadgets has evolved to be a major consideration of research as overuse of gadgets lead to rapid temperature rise and is in need of passive cooling system. Henceforth the newly developed nanocomposite phase change materials (PCMs) not only acts as thermal batteries but can also be opted as energy materials for thermal regulation and heat mitigation.

Lauric acid/stearic acid/nano-particles composite phase change materials for energy storage in buildings

Composite organic phase change materials (PCMs) have gained wide applications in buildings due to their superior latent heat capacity, stable properties, and most notably, the ability to adjust their melting temperatures as required. In this study, lauric acid (LA) and stearic acid (SA) were selected as the matrix of PCM, which is used to store and release thermal energy. The step-cooling curve method was utilized to test and draw the binary equilibrium phase diagram of the two materials. The composite PCM achieved its lowest eutectic temperature of 31.2 °C when the weight ratio of LA/SA was 7:3, demonstrating suitability for building envelopes. To enhance the thermal conductivity of the composite PCM, nano‑copper oxide (nano-CuO) and nano‑silicon dioxide (nano-SiO2) were added into the composite PCM as thermal conductivity enhancing materials. The study compared the effects of different dispersants, different nanoparticle to dispersant ratios, and nanoparticle concentrations on the stability and uniformity of the experimental materials. The thermal properties were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), thermal conductivity measurement, and thermal absorption and release process analysis. The findings indicate that the 0.2 %nano-CuO/PCM had remarkable stability, with reduced latent heat of melting and solidification by 5.91 % and 5.44 %, respectively, compared to the composite PCM. The thermal conductivity of the material was increased by 30.0 %. This study provides valuable insights for the development of novel nanocomposite PCMs specifically designed for thermal active building wall applications.

Expanded graphite intersperse reliable binary eutectic phase change material for low temperature thermal regulation systems

Inorganic phase change materials (PCMs) frequently stuck by ineffaceable thermal conductivity and degree of supercooling for thermal energy storage (TES) accomplishment. The present research work is dedicated to resolve this problem by developing a unique inorganic salt hydrate based binary eutectic PCM employing sodium sulphate decahydrate (SSD) and sodium phosphate dibasic dodecahydrate (SPDD) in eutectic mixture ratio 62:38 mass percentage. The peculiar eutectic composition of SSD/SPDD developed with melting and bath sonication technique manifests eutectic latent heat of 207.4 J/g and eutectic melting point of 27.8 °C. Furthermore, to elevate thermal performance and to descent degree of supercooling three dimension expanded graphite (EG) is interspersed as nanoparticle. Optical absorbance of composite PCM elevated from 0.16 for SSD/SPDD to 0.92 with SSD/SPDD + EG nanoparticles; inversely transmissibility of the composite reduced by 82.13 %. Heat flow curves ensures the melting temperature (26.9 °C–28.7 °C) of EG dispersed composite to be within the operating condition with latent heat of 220.4 J/g at 2.0 % of EG owing to the intermolecular binding force of attraction increases as nano-sized sheets effectively disperse with the base PCM. Subsequently, thermal conductance of nano composite eutectic PCM upraised from 0.453 to 0.855 W/m⋅K. After 200 thermal cycle's chemical optical and thermal stability of the PCM composite was degraded insubstantially due to the presence of impurities with longer service; this affirmed the stability thermal perks of nanocomposite PCM. Numerical analysis on heat transfer propagation of heat source within SSD/SPDD PCM layer with and without EG nanoparticle provides inference on the importance of thermal conductivity.

Rationally Tunable Phase Change Material Thermal Properties Enabled by Three-Dimensionally Printed Structural Materials and Carbon-Based Functional Additives

Passive cooling using phase change materials (PCMs) is a promising solution to address thermal challenges for modern electronics, electric vehicles, and energy storage systems. The high latent heat of PCMs can significantly decrease overheating or thermal shock; however, their low thermal conductivity and unstable shape limit their practical application. Herein, we report a multiscale rational design strategy for tuning the thermal properties of PCM (octadecane), enabled by 3D-printed structural materials and multiwalled carbon nanotubes (MWCNTs)/graphene nanoplatelets (GNPs), serving as PCM reservoirs and thermally functional additives. Octadecane, used as the PCM, was thermally reinforced with MWCNT/GNP functional additives using one- and two-dimensional thermal transport at the micro-/nanoscale, and the developed nanocomposite PCM was incorporated into the 3D-printed grid structures serving two purposes: thermal transport at the macroscale and mechanical support during the liquid–solid phase change. Thus, the fabricated 3D-printed structures with incorporated thermal energy management composites (3DS-TEMCs), with different infill density/MWCNT/GNP parameters, exhibited tunable latent heat/thermophysical properties and outstanding thermal conductivity (~0.45–0.79 W/(m K)) higher than that of pure octadecane (~0.15 W/(m K)). In passive cooling tests implemented in a local heating configuration, the 3DS-TEMCs inhibited overheating and thermal shock under transient thermal loads in the operating temperature ranges of electronic devices and batteries. The proposed 3DS-TEMC offers a tunable and scalable strategy to impart PCMs with advanced thermophysical characteristics compared to conventional PCMs.

Detailed experimentation and prediction of thermophysical properties in lauric acid-based nanocomposite phase change material using artificial neural network

The thermal conductivity (TC) of a nanocomposite phase change material (NPCM) may be improved by adding nanostructured materials to a Phase Change Material (PCM). To assess the heat transfer rate during the process of phase change, such as melting and freezing, an accurate TC prediction of NPCM is required. A Field Emission Scanning Electron Microscope (FESEM) was utilized to examine the nanoparticle morphological study, and X-Ray Diffraction (XRD) analysis evaluated the crystalline structure. NPCMs were verified using Fourier Transform Infrared Spectroscopy (FTIR). The goal of this research is to create an Artificial Neural Network (ANN) that guesses the TC and viscosity of Lauric Acid (LA) embedded with dispersed copper oxide (CuO) and aluminium oxide (Al2O3). A multi-layered feed-forward ANN (MLFFANN) is trained using the Levenberg-Marquardt (LM) backpropagation algorithm. There are 130 experimental datasets in total, obtained from experiments with nanoparticle mass fractions ranging from 1.25 to 10 wt%. The minimum mean square error (MSE) for TC and viscosity is 4.6815 × 10−5 and 2.4681 × 10−5, respectively. The average absolute deviation (AAD) for TC and viscosity is 0.004249 and 0.003596, respectively, while the mean absolute percentage error (MAPE) is 2.1835 % and 4.8197 % for TC and viscosity, and the correlation coefficients(R) are 0.992 and 0.975, respectively. The largest percentage variation between experimental values and ANN computed values for the liquid and solid phases, respectively, is 3.54 % and 0.832 %. It demonstrates that the constructed ANN prediction model predicts the increased TC and viscosity of NPCM for different nanoparticle loadings, temperatures, and oxide nanoparticles.

Thermo-kinetic behaviour of green synthesized nanomaterial enhanced organic phase change material: Model fitting approach

Metal, carbon and conducting polymer nanoparticles are blended with organic phase change materials (PCMs) to enhance the thermal conductivity, heat storage ability, thermal stability and optical property. However, the existing nanoparticle are expensive and need to be handle with high caution during operation as well during disposal owing to its toxicity. Subsequently handling of solid waste and the disposal of organic PCM after longevity usage are of utmost concern and are less exposed. Henceforth, the current research presents a new dimension of exploration by green synthesized nanoparticles from a thorny shrub of an invasive weed named Prosopis Juliflora (PJ) which is a agro based solid waste. Subsequently, the research is indented to decide the concentration of green synthesized nanoparticle for effective heat transfer rate of organic PCM (Tm = 35–40 °C & Hm = 145 J/g). Furthermore, an in-depth understanding on the kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM after usage via Coats and Redfern technique is exhibited. Engaging a two-step method, we fuse the green synthesized nanomaterial with PCM to obtain nanocomposite PCM. On experimental evaluation, thermal conductivity of the developed nanocomposite (PCM + PJ) increases by 63.8% (0.282 W/m⋅K to 0.462 W/m⋅K) with 0.8 wt% green synthesized nanomaterial owing to the uniform distribution of nanoparticle within PCM matrix thereby contributing to bridging thermal networks. Subsequently, PCM and PCM + PJ nanocomposites are tested using thermogravimetric analyzer at different heating rates (05 °C/min; 10 °C/min; 15 °C/min & 20 °C/min) to analyze the decomposition kinetic reaction. The kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM and its nanocomposite of PCM + PJ provides insight on thermal parameters to be considered on large scale operation and to understand the complex nature of the chemical reactions. Adopting thirteen different chemical mechanism model under Coats and Redfern method we determine the reaction mechanism; kinetic parameter like activation energy (Ea) & pre-exponential factor (A) and thermodynamic parameter like change in enthalpy (ΔH), change in Gibbs free energy (ΔG) and change in entropy (ΔS). Dispersion of PJ nanomaterial with PCM reduces Ea from 370.82 kJ/mol−1 to 342.54 kJ/mol−1 (7.7% reduction), as the developed nanomaterial is enriched in carbon element and exhibits a catalytic effect for breakdown reaction. Corresponding, value of ΔG for PCM and PCM + PJ sample within heating rates of 05–20 °C/min varies between 168.95 and 41.611 kJ/mol−1. The current research will unbolt new works with focus on exploring the pyrolysis behaviour of phase change materials and its nanocomposite used for energy storage applications. This work also provides insights on the disposal of PCM which is an organic solid waste. The thermo-kinetic profile will help to investigate and predict the optimum heating rate and temperature range for conversion of micro-scale pyrolysis to commercial scale process.

Green synthesized 3D coconut shell biochar/polyethylene glycol composite as thermal energy storage material

Developing stable, economic, safer and carbon-based nanoparticles from agro solid waste facilitates a new dimension of advancement for eco-friendly nanomaterials in competition to existing nanoparticles. Herewith, a three dimensional highly porous honeycomb structured carbon-based coconut shell (CS) nanoparticle is prepared through green synthesis technique using tube furnace to energies organic phase change material (PCM). CS nanoparticle synthesis using a green approach is incorporated with polyethylene glycol (PEG) using a two-step technique to develop PEG/CS nanocomposite PCM. Thermophysical features of the nanocomposites are characterized using transient hot bridge (ThB), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA), whereas optical property and chemical stability is evaluated using UV–Vis and FTIR spectrometers. Resulting nanocomposite demonstrates higher thermal conductivity by 114.5 % (improved from 0.24 W/m⋅K to 0.515 W/m⋅K). Energy storage enthalpy increased from 141.2 J/g to 150.1 J/g with 1.0 % weight fraction of CS nanoparticles. Optical absorbance of the nanocomposite is improved by 2.14 times compared to base PCM. The developed nanocomposite samples exhibit extreme thermal stability up to 215 °C. The 3D porous structure of CS nanoparticles shows better contact area with PEG, causing low interfacial thermal resistance for improved thermal network channels and pathways for extra heat transfer and phonon propagation.

Thermal performance and corrosion resistance analysis of inorganic eutectic phase change material with one dimensional carbon nanomaterial

The inherent thermal characteristics, supercooling phenomenon, and corrosion issues associated with salt hydrate phase change materials (PCMs) limit their practical applications. In this research work, we report a newly formulated eutectic salt hydrate PCM using a) sodium sulphate decahydrate (SSD) & b) sodium phosphate dibasic dodecahydrate (SPDD); with a focus on customizing its properties to enhance its suitability for low temperature thermal regulation (achieving a melting point of 27.8 °C and a high heat storage capacity of 215 J/g). Additionally, we have successfully reduced the degree of supercooling and introduced corrosion resistant properties to this PCM. To enhance both the thermal energy transfer rate and optical absorbance of the eutectic PCM, we have incorporated one-dimensional (1D) multiwall carbon nanotube (MWCNT) at various weight fractions, extending up to 0.9 %, utilizing a two-step method. The dispersion and chemical stability of SSD/SPDD + MWCNT nanocomposite are verified through the morphological visual and spectral peaks obtained in Fourier transfer infrared spectroscopy. Additionally, studies evaluating the optical and thermal property reveal a substantial 500 % increase in absorbance, a notable 77.9 % reduction in transmissibility, a thermal conductivity increase from 0.464 W/m⋅K to 0.742 W/m⋅K (reflecting a 59.9 % increment), and the retention of a consistent melting enthalpy of 218.6 J/g. This stability is attributed to the intermolecular interaction with MWCNT. Similary, the degree of supercooling (ΔTs) for the SSD/SPDD EPCM containing MWCNT decreased to 2.2 °C from 16.5 °C, marking an 86 % reduction compared to the pure eutectic salt solution. Furthermore, this composite demonstrated enhanced thermal and chemical stability throughout 200 thermal cycles. Auxiliary ANSYS simulation, with transient boundary condition, are provided to analyze the heat transfer interactions between the thermic fluid and the newly developed PCM when integrated into a thermal regulation system. Subsequently, a corrosion analysis of the developed eutectic PCM and the nanocomposite eutectic PCM exhibits a corrosion rate of 0.018 mpy, well below the permissible level (<5mpy). The insights gained from the development of this nanocomposite PCM offer valuable guidance for the design and creation of tailored eutectic PCM for low-temperature thermal regulation systems, resulting in significant energy savings.

Study on the competition effects between thermal conductivity and viscosity of graphene reinforced octadecane phase change material

In this study, a combination of microscale molecular dynamics (MD)-based and macroscale computational fluid dynamics (CFD)-based simulations are employed to investigate the effects of graphene with varying mass ratios on the thermal conductivity and viscosity of octadecane, revealing the nature of the competition effects of thermal conductivity and viscosity in the heat transfer process. The results show that graphene can significantly increase the average thermal conductivity of octadecane. But when its synergy angle in the direction of heat flux is close to 90°, the thermal conductivity of nanocomposite phase change materials (NCPCMs) is only 0.125 W·(m·K)−1, which is lower than that of pure octadecane by 18.83 %. The viscosity of NCPCMs decreased significantly with the decrease of graphene weight ratio and the increase of temperature, and the viscosity of NCPCMs with 9.15 wt% and 28.71 wt% at different temperatures was 812.65 % (max) and 313.75 % (min), respectively. Finally, the equilibrium point between the thermal conductivity and viscosity competition effects favors the viscosity side as the graphene mass ratio increases. Accordingly, natural convection became more crucial in the heat transfer process as the graphene mass ratio increased. Consequently, NCPCMs with the best heat transfer performance should possess a low graphene mass ratio, which results in a high Rayleigh number, providing them with high synergistic efficiency.

Thermal transport properties of composite phase change materials characterized by molten carbonate-ceramic date nucleus occupancy structure: A molecular dynamics study

Carbonate molten salts play a crucial role in energy transmission and storage for concentrated solar power (CSP) plants. In this study, a design strategy employing a date nucleus occupation structure was proposed for carbonate molten salt/ceramic SiO2 composite phase change materials (PCMs). Molecular dynamics (MD) simulations were conducted to investigate the thermal transport properties and nanoscale atomic structure of the Nanocomposite phase change materials (NPCM) system. The findings revealed that the incorporation of SiO2 nanoparticles significantly reduced the melting point of NPCM system, offering a favorable way to regulate the operating temperature range of the system. Moreover, the thermal conductivity and specific heat capacity of NPCM system increased with the increase in the radii of nanoparticles, reaching up to 12.32% and 6.061%, respectively. However, it was observed that larger nanoparticles limited the migration of particles, leading to a decrease in the self-diffusion coefficient (D) of the system. This study provides valuable insights in the design and application of CSP power plants utilizing nano-phase change materials.

Investigation on Thermophysical Properties of Multi-Walled Carbon Nanotubes Enhanced Salt Hydrate Phase Change Material

Thermal Energy Storage (TES) is a valuable tool for improving the energy efficiency of renewable energy conversion systems. One of the most effective methods for harnessing thermal energy from solar sources is through energy storage using phase change materials (PCMs). However, the thermal performance of PCMs is hindered by their low thermal conductivity. This research focuses on enhancing the thermal performance of salt hydrate PCM using multi-walled carbon nanotubes (MWCNTs) and surfactants. Through experimental investigations, a salt hydrate PCM with varying concentrations of MWCNTs (ranging from 0.1% to 0.9%) was prepared using a two-step technique and their thermophysical properties were thoroughly characterized. Various techniques such as field emission scanning electron microscope, thermal conductivity analyzer, ultraviolet-visible spectrum, thermogravimetric analyzer, and Fourier transform infrared spectroscopy were utilized to study the effect of surfactant on the nanocomposites and examine their morphology, thermal conductivity, optical properties, thermal stability, and chemical stability. The results indicated that the inclusion of MWCNTs with salt hydrate significantly improved the thermal conductivity by 68.09% at a concentration of 0.7 wt %, compared to pure salt hydrate. However, this enhancement in thermal performance was accompanied by a reduction in optical transmittance in the developed nanocomposite PCM. Additionally, the formulated nanocomposite demonstrated excellent thermal and chemical stability up to temperatures as high as 468 °C. As a result, this nanocomposite shows great promise as a potential candidate for solar TES applications, offering favourable characteristics for efficient energy storage from solar sources.