Composite Phase Change Materials Research Articles

Nanoarchitectonics of shape-stable composite phase change membrane based on multi-walled hollow microspheres for light-to thermal conversion

The development of shape-stable composite phase change materials (CPCMs) with outstanding light absorption and light-to thermal conversion performance is of great significant for harvesting and converting solar energy. Herein, we proposed a novel shape-stable composite phase change membrane based on multi-shelled hollow spheres (MHS) via a facile method. The MHS was fabricated by hydrothermal reaction and calcination treatment, and membrane was directly coated on glass plates after bonding the MHS. The as-resulted membranes possess excellent tensile strength, superior light absorption and light-to thermal conversion efficiency. The tensile strength of the membrane based MHS loaded 1-Hexadecylamine (HDA) can reach to 1.01 MPa. The light absorption of the membrane is about 93% under 1sun irradiation, and the photothermal conversion efficiency of the membrane is 81.4%. Moreover, the electro-to thermal conversion and heat dissipation of the membrane based CPCM were investigated. The results demonstrate that this membrane-based CPCM can not only be applied in solar energy capture, storage and conversion, but also has the prospect of being applied in the fields of electro-to thermal conversion and heat dissipation.

Experimental study and gradient-based ensemble intelligent computing to investigate effect of ultrasound on rheological behavior of bio-based phase change materials

The influence of ultrasound on the rheological behavior of new phase change material (PCM) is investigated. The PCMs are made from natural biological materials containing silicon carbide (SiC) nanoparticles or expanded graphite (EG) powders with weight fractions of 0, 0.05, 0.1, and 0.2 %. The rheological behavior of PCM composites is tested by a rheometer with shear rates of 10 up to 250 rpm. Surveys showed the smallest PCMs' viscosity at shear rates over 100 rpm is obtained for the highest sonication time. Results depict an ignorable change in the dynamic viscosity of PCMs with shear rate, and the shear thinning behavior reduces the PCMs' viscosity by raising the shear rate by 10–140 rpm. Results for EG/PCM and SiC/PCM composites showed non-Newtonian behavior at low shear rates. However, steadiness in viscosity at a shear rate higher than 140 rpm is observed for the Newtonian behavior of PCMs. The other outstanding consequence of this study is the development of novel robust machine learning, namely CatBoost, to simulate the rheological behavior of understudy nano-PCMs based on the weight fraction, sonication time, and shear rate. The multigene genetic programming (MGGP) as a comparative model is adopted to validate the primary model and provide a relationship for estimating the viscosity of each nano-PCMs. Simulation results revealed the superiority of the CatBoost (PCM-EG: R = 0.978 and RMSE = 1.739 mPa·s; PCM-SiC: R = 0.996 and RMSE = 0.374 mPa·s) to the MGGP (PCM-EG: R = 0.967 and RMSE = 2.103 mPa·s; PCM-SiC: R = 0.992 and RMSE = 2.368) in PCM composites.

Highly thermal conductive and rechargeable 3D liquid metal network-based phase change composite enabling photothermal pad

This paper presents a liquid metal network-based phase change composite material (LM-PCM) with enhanced photothermal conversion and heat storage capability. In this work, the graphite flake@copper fillers are incorporated into LM to increase the thermal conductivity of metallic composite filler and increase the viscosity of LM-based composite. Hot-pressing method has been applied to construct highly thermal conductive LM network within PCM matrix. The surface of LM-PCM is spray-coated with graphite layer to collect solar energy and convert it into heat. The obtained LM-PCM exhibits thermal conductivity as high as ∼7 W/m·K with 50 vol% metallic filler and light absorption efficiency of ∼90%. Moreover, such LM-PCMs have been demonstrated to be thermally rechargeable, producing less pollution than the other disposable thermal pads. The development of LM-PCM shows great prospect as thermal comforting material for clinical therapy, and also provides a new solution for the application of LM-based composites.

Biomass-derived porous carbon aerogels for effective solar thermal energy storage and atmospheric water harvesting

Solar-powered hydrated salt-based phase change materials have great potential in the field of solar building energy efficiency. However, hydrated salts suffer from leakage, subcooling and phase separation in practical applications. To address these problems, this study proposes a solution to encapsulate hydrated salt with biomass-derived carbon aerogel as a carrier, which can effectively mitigate the leakage, subcooling, and phase separation problems of hydrated salt without the need of additional modifiers. The composite phase change material exhibited high phase change enthalpy retention (92%), negligible supercooling (0.4 °C), and excellent photothermal conversion efficiency (91.5%). In addition, thanks to the rich porosity and superhydrophilicity of the carbon aerogel, a composite hygroscopic agent combined with lithium chloride was prepared for high-performance atmospheric water harvesting. The composite hygroscopic material has a moisture adsorption capacity of 2.1 g g−1 at 90% RH and can desorb more than 92.3% of the moisture by solar energy drive. The performance was stable after several adsorption-desorption cycles. The multifunctional composites based on biomass-derived carbon aerogels have excellent performance in solar thermal storage and atmospheric water harvesting, providing a new perspective on solar thermal utilization.

Phase transition characteristics and supercooling suppression of erythritol with organic salts as nucleating agents

The main aim of this paper is to mitigate the supercooling of erythritol using organic salts as nucleating agents. The pure erythritol exhibits significant volume effects and a strong supercooling tendency. When the aspect ratio of the ET is small, a metastable phase transition plateau at 105 °C can be observed, and then, the metastable crystal slowly transforms into a stable crystal. Experimental results reveal that calcium pimelate (CaPi) has a positive influence on the supercooling elimination of erythritol. The 1 % CaPi/erythritol composite phase change material (CPCM) melts at 118 °C and solidifies at 109 °C with the latent heat of 344.86 J/g and 281.8 J/g, respectively. Due to the improved crystallization kinetics, the supercooling phenomenon measured by T-history method is basically eliminated. The melting heat is >300 J/g and the change of phase change temperature is less after 50 cycles. In order to simulate the real environment, the CPCM cools down by room temperature in air, and the chemical stability is good. The thermal conductivity of 1 % CaPi/ET increases by 23.2 %. In total, the CaPi/erythritol CPCM is a new candidate to be used in waste heat recovery, solar energy medium temperature heat collection and other fields.

A novel flexible carbon fiber with carbon nanotubes growing in-situ via chemical vapor deposition to impregnate paraffin for thermal energy application

Aiming at solid waste resources reuse and energy saving issue, a novel flexible paraffin/carbon [email protected] nanotubes (Paraffin/[email protected]) composite PCM was prepared in this study. In the flexible composite PCM, CNTs grew in-situ surrounding by recycled CF trunk via chemical vapor deposition to construct the fiber net-structure utilized as the supporting material, and paraffin as a thermal energy storage material was absorbed into spongy [email protected] by vacuum impregnation methods. The prepared Paraffin/[email protected] composite has a best solid-liquid phase change latent heat of 81.94 Jg−1 after solid-solid phase transition with 15.28 Jg−1, and still keep the high latent heat retention of 99.4 % even after being subjected to 300 melting/freezing cycles. The thermal conductivity of Paraffin/[email protected] composite (1.551 Wm−1 K−1) is enhanced by up to 573 % than that of pure paraffin, while this composite exhibits the good thermal stability that it decomposes over 215.6 °C with totally 51.9 % mass loss. Overall, the novel flexible Paraffin/[email protected] composite PCM behaves very stable performances in structure, chemical component, thermal storage and thermal stability, looking promising for applications in electronic device temperature control, near-infrared stealth, smart wear and textile industries.

Fabrication and investigation of paraffin based shape-stable composite phase change materials with styrene ethylene butylene styrene as supporting skeleton for low temperature thermal energy storage and management

Paraffin based composite phase change materials (PCMs) have gained intensive attentions in low temperature thermal energy storage (TES) and management application domains because of its suitable melting temperature range and advanced thermoproperties. Seeking decent structural supporting materials (SSM) and the associated manufacturing approaches that capable of fabricating paraffin composites at appropriate temperatures to avert the thermal decomposition of the paraffin particularly for low-molecule ones are in high demand. Herein, we developed a low-molecule paraffin (RT18HC) composite through a simple blending approach by using styrene-ethylene/butylene-styrene (SEBS) as SSM, and showed that such SEBS-paraffin composites could be able to fabricate at a low operation temperature of 80 °C, significantly lower than that required for the preparation of conventional high density polyethylene (HDPE)-paraffin composites. To enhance the composite effective thermal conductivity, a micro-sized graphite power as enhancer was also involved over the fabrication process. Owing to the desirable solubility of paraffin in SEBS, a crosslinking structure inlaying paraffin and graphite was formed, endowing the composite with ability to maintain the structure stabilization and eliminate the graphite sedimentation over the repeated thermal cycles. 10 wt% of SEBS gives the composite optimum formulation at which 10 wt% graphite can be involved, and also an excellent shape stability and thermal adjustment ability can be achieved.

Electro- and photo-thermal energy conversion investigation of polyethylene glycol infiltrated porous carbon aerogels

Due to the insulating nature of organic phase change materials, it is impossible to directly trigger latent heat thermal energy storage via an electrical way. In this work, through crosslinking, freeze-drying and pyrolysis, the interconnected carboxymethylcellulose sodium-derived carbon aerogel (abbreviated as CCA) with high porosity, good solar-thermal conversion capability, electrical conductivity, and mechanic strength is firstly fabricated successfully. The organic phase change material of polyethylene glycol (PEG) is then infiltrated into the CCA via vacuum infiltration to obtain the PEG/CCA15 composite phase change materials that melt at 52.1 °C with latent heat of 173.4 J/g. Electro-thermal test results display that PEG/CCA15 composite present low resistance (1.64 Ω), high electrical conductivity (4.201 S/cm) and excellent electro-thermal energy conversion efficiency (55.6 % under applying 1.4 V). Further results also show that PEG/CCA composites exhibit good photo-thermal energy storage and release abilities. Our results indicate that the as-prepared PEG/CCA15 is a potential candidate to be applied in electrical/solar energy utilization.

An approach to utilize date seeds biochar as waste material for thermal energy storage applications

Rapid industrialization as a consequence of the green revolution and population proliferation has resulted in massive solid waste generation as well as greater energy consumption demands. With increasing energy demand coupled with ever-increasing waste generation, the time has come to think about global sustainability. The practice of green technology which is ecologically benevolent might be the foothold of waste management that renders resolutions. Therefore, waste valorization in sustainable energy forms can bring up an economic and suitable solution for the sustainability of civilization. Contemplating that, an attempt has been made to utilize date seeds as waste material for shape stabilization of phase change materials (PCMs) for effective thermal energy storage applications. Date seeds (DS) are ground to powder and pyrolyzed into porous biochar, having high porosity and channel-like morphology with a BET surface area of 187.07 m2/g. The PCM composites are accomplished by introducing capric acid (CA) into synthesized biochar (DSB). CA has been incorporated in 2:1 and 3:1 ratios into DSB and the thermal stability along with performance of the synthesized DSCA composites have been evaluated for their suitable applications. The 3:1 CA to DSB ratio has been realized as optimum for the highest accommodation of CA into DSB. Higher heat charging and discharging enthalpies of 72.4 and 71.76 J/g are accomplished for 1–3 DSCA sample as well as encapsulation efficiency and ratio are found to be 43.79 % and 43.96 %, respectively. During phase transitions, excellent leakage resistance and congruent heat charging and discharging capabilities have been manifested by the DSCA samples. The extraordinary performances displayed by the DSCA PCM composites are attributed to the surface tension, capillary action, space confinement and surface functionalities offered by the porous biochar.

Experimental Transient Performance of Heat Sink with Phase Change Material and Movable Metal Foams Insert

The effects of embedding fixed and movable metal foams in composite PCMs on the transient performance were studied with pulsed heat loads experimentally under various powers and different cell sizes. Similar conclusions could be drawn both from the experimental and numerical results. It was shown that when fixed metal foams were solely adopted, the heat storage system performance could be enhanced by ∼24.6% by increasing the number of metal foams by three times at the heat flux of 56.1 W/cm2 and 15 ppi. When the movable technique was utilized, the heat transfer enhancement reached up to 36.9% under the same amount of metal foams for the same cell sizes and heat flux. The better performances were attributed to combined positive influences due to the adoption of the movable metal foam technique, which extends heat transfer area, improves heat conduction, and eases suppression of natural heat convection by cutting the amount of metal foams. Moreover, as cutting the amount of metal foams could obviously reduce the wastage of energy storage capacity, the movable metal foam technique demonstrated quite a promising future.

Form-Stable Composite Phase Change Material Based Cooling of Small Brushless DC Motor Windings

Form-Stable Composite Phase Change Material Based Cooling of Small Brushless DC Motor Windings

Beeswax as a potential replacement of paraffin wax as shape stabilized solar thermal energy storage material: An experimental study

Thermal Energy Storage (TES) using paraffin wax as Phase Change material (PCM) has been widely used for solar to thermal energy conversion and storage application. Being petroleum by-product, production of paraffin wax have embodied environmental impact and high carbon footprint. Beeswax can replace paraffin's as one of the clean, sustainable, eco-friendly and potential TES PCM. However, TES potential of Beeswax was not investigated thoroughly in previous literatures. Also, limited study has been found which evaluates solar to thermal conversion potential of Beeswax. This study presents a comprehensive analysis of TES performance of Beeswax supported by Bentonite clay and loaded with Graphite was evaluated. Bentonite clay was used as supporting material and Graphite powder is used as additive in varying percentage to form Shape Stabilized Composite Phase Change Material (SSCPCM). SSCPCM was initially investigated for anti-leakage behaviour and was found that Bentonite can hold maximum 40 wt% of Beeswax without leakage above phase transition temperature. Thermal energy storage parameters, thermal degradation, solar to thermal conversion performance, chemical stability, surface morphology, and thermal conductivity were evaluated. Bentonite and graphite has shown good morphology to form SSCPCM samples. Also, SSCPCM has proved to be chemically and physically stable thermal energy storage material. Melting enthalpy of 101.79, 100.66, 98.80, 100.43, 96.51, and 105.01 at melting point of 59.43, 58.88, 58.12, 57.98, 57.36, and 57.11 of SSCPCM-0, SSCPCM-1, SSCPCM-3, SSCPCM-5, SSCPCM-7, and SSCPCM-9 was obtained. Adding Graphite has reduced supercooling of SSCPCM samples maximum by 84.13 %. Increasing additives in PCM improves heating rate and thermal conductivity of the SSCPCM.

Activated carbon/expanded graphite hybrid structure for development of nonadecane based composite PCM with excellent shape stability, enhanced thermal conductivity and heat charging-discharging performance

Activated carbon/expanded graphite hybrid structure for development of nonadecane based composite PCM with excellent shape stability, enhanced thermal conductivity and heat charging-discharging performance

Eco-friendly coconut shell biochar based nano-inclusion for sustainable energy storage of binary eutectic salt hydrate phase change materials

Eco-friendly, stable and thermally reliable nano enhanced phase change materials (PCMs) with improved thermal property and photo absorbance are vital competencies for solar energy harnessing. In the proposed research, we develop and investigate the morphological, chemical, optical and thermal features of biochar-eutectic PCM composite for clean energy storage. Herewith, primarily coconut shell-based biochar nanoparticle (BNP) is synthesized through carbonization process in vacuum oven at 130 °C followed by wet ball milling to reduce the size. Coconut shell being a feasible candidate in terms of economical, pore structured and light weight ensures better binding, uniform dispersion and improved intermolecular attraction with PCM. The synthesized BNP is evenly spread into the surface morphology of inorganic binary eutectic PCM comprising of 62% of sodium sulphate decahydrate (SSD) and 38% of sodium phosphate dibasic dodecahydrate (SPDD). Electromagnetic spectrum absorbance in the range of infrared and visible rays increased from 0.09 to 0.84 (833%) and transmissibility has been reduced from 83.7% to 15.11% with BNP. Developed BNP composite eutectic PCM demonstrate higher thermal conductivity (0.715 W/m⋅K) on comparison with base eutectic PCM (0.464 W/m⋅K) owing to the presence of carbon element and porous nature of BNP. Heat flow curves specifies increment in melting enthalpy of eutectic PCM from 202.3 J/g to 218.1 J/g with energy storage efficiency of 71.7%. On the basis of thermophysical properties obtained, the developed BNP composite PCM is expected to contribute effectively for thermal regulation applications.

Novel gypsum based plasters with phase change material impregnated lightweight aggregates for energy efficient retrofitting

This study developed a novel gypsum plaster comprised of high energy storage phase change material (PCM) loaded granules to reduce the amount of energy used in buildings. Changes in the mechanical and thermal properties of gypsum plasters are reported and compared with PCM-loaded cement mortars. Analysis of the energy consumption through simulation showed the amount of PCM-loaded granules and their location in the building material have a significant impact on the effectiveness of the PCM composites. The maximum energy savings of 293.8 kWh were achieved when PCMs granules were incorporated to cement blocks. However, maximum thermal comfort was achieved with PCM gypsum plaster.

Co/N co‐doped flower‐like carbon‐based phase change materials toward solar energy harvesting

AbstractThe photothermal conversion capacity of pristine organic phase change materials (PCMs) is inherently insufficient in solar energy utilization. To upgrade their photothermal conversion capacity, we developed bimetallic zeolitic imidazolate framework (ZIF) derived Co/N co‐doped flower‐like carbon (Co/N‐FLC)‐based composite PCMs toward solar energy harvesting. 3D interconnected carbon framework with low interfacial thermal resistance, abundant carbon defects and high content of nitrogen doping, excellent localized surface plasmon resonance (LSPR) effect of Co nanoparticles, and light absorber Co3ZnC in Co/N‐FLC synergistically upgrade the photothermal capacity of (polyethylene glycol) PEG@Co/N‐FLC composite PCMs with an ultrahigh photothermal conversion efficiency of 94.8% under 0.16 W/cm2. Uniformly anchored Co and Co3ZnC nanoparticles in carbon framework guarantee excellent photon capture ability. Bridging carbon nanotubes (CNTs) in 2D carbon nanosheets further accelerate the rapid transport of phonons by constructing cross‐connected heat transfer paths. Additionally, PEG@Co/N‐FLC exhibits a thermal energy storage density of 100.69 J/g and excellent thermal stability and durable reliability. Therefore, PEG@Co/N‐FLC composite PCMs are promising candidates to accelerate the efficient utilization of solar energy.

A Novel Molecular PCM Wall with Inorganic Composite: Dynamic Thermal Analysis and Optimization in Charge-Discharge Cycles.

The combination of electric heating and thermal energy storage (TES) with phase change material (PCM) can achieve load shifting for air conditioning energy saving in building sectors. Their non-flammability, relatively good mechanical properties, and low cost make inorganic PCMs attractive in construction engineering. However, PCMs often show poor thermal conductivity, low heat transfer efficiency, leakage risk, etc., in applications. Moreover, the practical thermal performance of PCM-TES sometimes fails to meet demand variations during charge and discharge cycles. Therefore, in this study, a novel integrated electric PCM wall panel module is proposed with quick dynamic thermal response in space heating suitable for both retrofitting of existing buildings and new construction. Sodium-urea PCM composites are chosen as PCM wall components for energy storage. Based on the enthalpy-porosity method, a mathematical heat transfer model is established, and numerical simulation studies on the charge-discharge characteristics of the module are conducted using ANSYS software. Preliminary results show that the melting temperature decreases from 50 °C to approximately 30 °C with a 30% urea mixing ratio, approaching the desired indoor thermal comfort zone for space heating. With declining PCM layer thickness, the melting time drops, and released heat capacity rises during the charge process. For a 20 mm thick PCM layer, 150 W/m2 can maintain the average surface temperature within a comfort range for 12.1 h, about half the time of a 24 h charge-discharge cycling periodicity. Furthermore, placing the heating film in the unit center is preferable for improving overall heat efficiency and shortening the time to reach the thermal comfort temperature range. This work can provide guidance for practical thermal design optimization of building envelopes integrated with PCM for thermal insulation and energy storage.

Enhancing thermal performance of latent heat storage unit for solar cooling: A hybrid approach with C-shaped fins and nano-additives

The performance of solar cooling systems is significantly affected by the intermittent nature of solar energy. To address this problem, thermal energy storage systems such as sensible and latent heat storage systems can be a viable option. Among these, the latent heat storage systems are promising due to their high energy storage density and nearly isothermal charging/discharging characteristics. However, the low thermal conductivity of the phase change material used within the storage unit hinders heat transfer, leading to longer charging and discharging periods. To overcome this problem, a hybrid approach that uses fins and nano additives is proposed in this study. A novel C-shaped fin design is introduced that effectively utilises the natural convection current in the molten phase change material. A comprehensive geometrical and material optimisation study is performed to determine the optimal shape, position, and material of the fins. The study also investigates the effect of the inclusion of graphene nanoplatelets (GnP) on the latent heat storage units. An experimental study is conducted to characterise the composite phase change material, and empirical correlations for viscosity and thermal conductivity are developed. The performance of an optimally designed LHS stacked with nano PCM composite of varying mass fractions is also evaluated. The study reveals that the C-shaped fins can reduce melting time by up to 59% compared to conventional fin designs, while PCM dispersed with 1% GnP reduces melting time by 27% when compared to the base PCM. Finally, a two-bed solar vapour adsorption cooling system with a 500 W capacity is considered to conduct a case study for demonstrating the performance of the proposed LHS. The result shows that the solar adsorption system integrated with the proposed heat storage unit can operate up to 3.3 h longer than it currently does. Thus the study presents a promising solution to overcome the obstacles limiting the widespread utilisation of solar cooling systems.

Comprehensive thermal properties of ternary eutectic molten salt/nanoparticles composite phase change materials for high–temperature thermal energy storage

Chlorine and fluorine salts are very promising thermal storage media for high–temperature thermal energy storage (TES) systems. In this study, NaCl–KCl–NaF/nanoparticles composite phase change materials (CPCMs) were employed by an advanced high–temperature and high–pressure reactor. NaCl–KCl–NaF was adopted as the BS, while CuO and Al2O3 nanoparticles have been uniformly dispersed in different ratios to generate CPCMs from the base salt (BS). Microscopic characterization, thermal properties characterization, and economic analysis of CPCMs and the BS were performed. The findings revealed that the best results were obtained when the BS was added with 0.5 wt percent Al2O3 and 0.5 wt percent CuO nanoparticles, CPCMs have improved solid/liquid thermal conductivity by a factor of 3.70 and 1.84, and TES density by a factor of 1.13, while reducing the cost per unit of TES density by approximately 26.8%. In addition, the CPCMs and BS possess excellent operating temperature range and thermal stability, whereby they are applicable in high–temperature TES systems.

A Review of Recent Improvements, Developments, Effects, and Challenges on Using Phase-Change Materials in Concrete for Thermal Energy Storage and Release

Most concrete employs organic phase change materials (PCMs), although there are different types available for more specialised use. Organic PCMs are the material of choice for concrete due to their greater heat of fusion and lower cost in comparison to other PCMs. Phase transition materials are an example of latent heat storage materials (LHSMs) that may store or release thermal energy at certain temperatures. A phase transition occurs when a solid material changes from a solid state to a liquid state and back again when heat is added or removed. It is common knowledge that adding anything to concrete, including PCMs, will affect its performance. The goal of this review is to detail the ways in which PCMs affect certain concrete features. This overview also looks into the current challenges connected with employing PCMs in concrete. The review demonstrates a number of important findings along with the possible benefits that may pave the way for more research and broader applications of PCMs in construction. More importantly, it has been elucidated that the optimum PCM integrated percentage of 40% has doubled the quantity of thermal energy stored and released in concrete. Compared to conventional concrete, the macro-encapsulated PCMs showed thermal dependability, chemical compatibility, and thermal stability due to delaying temperature peaks. Furthermore, the maximum indoor temperature decreases by 1.85 °C and 3.76 °C in the test room due to the addition of 15% and 30% PCM composite, respectively. Last but not least, incorporating microencapsulated PCM has shown a positive effect on preventing freeze-thaw damage to concrete roads.