Composite Thermal Energy Storage Research Articles

Multiscale Porous Architecture Consisting of Graphene Aerogels and Metastructures Enabling Robust Thermal and Mechanical Functionalities of Phase Change Materials

AbstractPassive thermal energy storage systems using phase change materials (PCMs) are promising for resolving temporal‐spatial overheating issues from small‐ to large‐scale platforms, yet their poor shape stability due to solid–liquid transition incurs PCM leakage and weak resistance against mechanical disturbance, limiting practical applications. While foam‐stable templates for PCMs have shown complement, they reveal massive leakage and collapse of liquefied PCMs under external loads or impacts. Herein, a multiscale porous architecture consisting of graphene aerogels (GAs) and meta structures enabling robust thermal‐mechanical functionalities of PCMs (3D‐MPGA) toward sustainable phase change thermal energy storage composites is reported. 3D‐printed mechanical metamaterials employing octet‐truss cells provide supportive strength and directionally‐assisted leakage reduction, while GAs serve as porous templates with surface‐interfacial contacts, thereby fixing paraffin wax as PCM inside their nano/micropores. The 3D‐MPGA shows intrinsic thermal characteristics of bulk PCMs, and improved thermal‐mechanical‐chemical stability, confirmed by long‐term heating‐cooling cycle tests over 10 h. Moreover, it exhibits highly reinforced strength (200–5000%) within a low density across ambient and melting temperatures, and maintains original shapes in the liquefied PCMs without severe leakage, against external loads. This work inspires rational strategies for advancing robust thermal‐mechanical functionalities for PCM‐based thermal energy storage systems.

Enhanced Gypsum Boards with Activated Carbon Composites and Phase Change Materials for Advanced Thermal Energy Storage and Electromagnetic Interference Shielding Properties

This work presents the development of novel gypsum board composites for advanced thermal energy storage (TES) and electromagnetic interference (EMI) shielding applications. Activated carbon (AC) derived from spent coffee with a high surface area (SBET = 1372 m2/g) was used as a shape stabilizer, while the commercial paraffin, RT18HC, was used as organic encapsulant phase change material (PCM). The AC showed a remarkable encapsulation efficiency as a shape stabilizer for PCM, with ~120.9 wt% (RT18HC), while the melting enthalpy (ΔHm) of the shape-stabilized PCM was 117.3 J/g. The performance of this PCM/carbon nanocomposite as a thermal energy storage material was examined by incorporating it into building components, such as gypsum wallboards. The microstructure of these advanced panels, their density, and their dispersion of additives were examined using X-ray microtomography. Their thermal-regulated performance was measured through a self-designed room model with a similar homemade environmental chamber that was able to create a uniform temperature environment, surrounding the test room during heating and cooling. The measurements showed that the advanced panels reduce temperature fluctuations and the indoor temperature of the room model, in comparison with normal gypsum panels, by a range of 2–5%. The investigated gypsum board composite samples showed efficient electromagnetic shielding performance in a frequency range of 3.5–7.0 GHz, reaching an EMI value of ~12.5 dB, which is adequate and required for commercial applications, when filled with PCMs.

One-pot in situ synthesis of expandable graphite-encapsulated paraffin composites for thermal energy storage

To mitigate the intermittency of renewable energy generation and achieve net-zero greenhouse gas emissions, a cyclically stable and energy-efficient thermal energy storage system (TESS) is increasingly required. To prevent leakage and enhance thermal conductivity and stability, TESS is typically fabricated by impregnating energy storage materials (ESMs) into porous conductive additives. However, the impregnation-based encapsulation process is both time-consuming (several to tens of hours) and energy-intensive, and the incorporation of additives reduces the proportion of ESMs, resulting in decreased energy capacity. In this study, we present an ultrafast (several minutes) and energy-efficient one-pot encapsulation method for in situ encapsulation of paraffin wax (PW) within the pores of expanded graphite (EG) via microwave irradiation of expandable graphite (Eg) in molten PW. The resulting binary PW/EG composites exhibit shape stability and no leakage even at 92 wt% PW loading. The PW/EG composite with 10 wt% EG demonstrates a thermal conductivity of 3.7 W/mK (16.2 times higher than that of pure PW), a thermal release/absorption efficiency of around 99.5 %, and almost 100 % capacity retention after thermal cycling. Additionally, we demonstrate that integrating PW/EG TESS with thermoelectric (TE) modules can increase TE power generation by more than fivefold, highlighting their potential for energy storage and conversion as well as mitigating waste heat source intermittency.

Improved Thermophysical and Mechanical Properties in LiNaSO4 Composites for Thermal Energy Storage.

Solid-solid phase-change materials have great potential for developing compact and low-cost thermal storage systems. The solid-state nature of these materials enables the design of systems analogous to those based on natural rocks but with an extraordinarily higher energy density. In this scenario, the evaluation and improvement of the mechanical and thermophysical properties of these solid-solid PCMs are key to exploiting their full potential. In this study, LiNaSO4-based composites, comprising porous MgO and expanded graphite (EG) as the dispersed phases and LiNaSO4 as the matrix, have been prepared with the aim of enhancing the thermophysical and mechanical properties of LiNaSO4. The characteristic structure of MgO and the high degree of crystallinity of the EG600 confer on the LiNaSO4 sample mechanical stability, which leads to an increase in the Young's modulus (almost three times higher) compared to the pure LiNaSO4 sample. These materials are proposed as a suitable candidate for thermal energy storage applications at high temperatures (400-550 °C). The addition of 5 wt.% of MgO or 5% of EG had a minor influence on the solid-solid phase change temperature and enthalpy; however, other thermal properties such as thermal conductivity or specific heat capacity were increased, extending the scope of PCMs use.

Experimental study of phase transition heat of composite thermal energy storage materials paraffin wax/expanded graphite

In this paper, the effect of the expanded graphite (EG) matrix on the phase transitions enthalpy of phase change material (PCM) is studied experimentally. For this purpose, the paraffin wax (PW) containing EG (up to 6.5 wt%) was explored in terms of the effective heat capacity and a diffuse phase transitions enthalpy difference over the 25–65 °С temperature range. Composite PCMs PW/EG was prepared using a new method and were inherent in high pores fill factor. The main advantage of the proposed method is preliminary vacuuming of the PW and EG with subsequent mixing and sonication under vacuum. The EG choice was based on the hypothesis that the EG matrix contributes to modifying the PW internal structure due to the PW molecules' adsorption on the EG surface during PCM cooling and solidification. Consequently, a significant change in PW/EG caloric properties vs. pure PW was observed. The EG presence in PW reverses the enthalpy hysteresis in the heating-cooling cycle vs. pure PW. The enthalpy difference during PW heating and melting in the range of 30–60 °С is higher than during its cooling and solidification: 336.2 J∙g−1 vs. 214.9 J∙g−1. On the contrary, the enthalpy difference of melting for PW/EG of 3.6 wt% in the range 30–60 °С was 171.2 J∙g−1 vs. 273.8 J∙g−1 during solidification. The obtained results are explained by the different dynamics of processes of PW melting and solidification in EG matrix pores. The presence of the 3.2–6.5 wt% of EG in PW contributes to an increase in solidification enthalpy difference in the range 30–60 °C on 27–33 % vs. pure PW. A decrease in the melting enthalpy difference for PW/EG on 44–50 % vs. pure PW was recorded in the range of 30–60 °C. In addition, thermal conductivity was measured to confirm the advantages of PW/EG as PCM. Thermal conductivity for PW/EG with EG content of 3.6 and 6.5 wt% at 25 °C was 8.9 and 9.6 times higher than for pure PW. Similarly, 8.8 and 10.9 times thermal conductivity increase was observed at 65 °C. The composite PCM containing 3.6 wt% of EG in PW obtained by developed method can be recommended as a rational composition in benefit of the thermal conductivity and caloric properties for utilization in high-performance TES systems.

Plastic composite of bamboo charcoal stabilized polyethylene glycol with thermal energy storage and temperature regulation for building energy efficiency

AbstractPhase change materials (PCMs) are often used as building materials to reduce the energy consumption. However, conventional PCMs are susceptible to leakage and have a short service life. To solve this problem, thermal energy storage (TES) composites were fabricated by using bamboo charcoal (BC) encapsulating polyethylene glycol (PEG) as the PCM and low density polyethylene (LDPE) as the matrix. The shape and structure of BC and BC‐plastic composites were examined using scanning electron microscopy, X‐ray diffractometry, and mercury intrusion porosimetry. Differential scanning calorimetry, thermogravimetry (TG), and infrared thermography were used to characterize the manufactured TES composites. Physical and mechanical strength assessments were also conducted. The results demonstrated that: (1) BC possessed a rich void structure with a porosity of 61.4%, which could be used to adsorb PEG and the composites was a combination of PEG, BC, and LDPE with no chemical reaction; (2) thermal tests demonstrated that the composites exhibited favorable temperature regulation properties, featuring a maximum latent heat capacity of 29.1 J/g along with suitable phase change temperatures, yet thermal durability needs to be improved much further, addition of PEG reduced thermal conductivity of the composite from 0.38 to 0.34 W/mK; (3) the addition of PEG was beneficial for the impact strength but had a negative impact on the flexural and tensile properties; and (4) due to their satisfactory thermal performance and acceptable mechanical properties, these TES composites can be effectively utilized as building materials for temperature control purposes.Highlights Bamboo charcoal (BC) had a large number of pores that can encapsulate polyethylene glycol (PEG). PEG/BC performed satisfactory latent heat. Low density polyethylene was used as the matrix to realize the second encapsulation of phase change material. Thermal energy storage composites had excellent stability and good heat storage capacity. PEG incorporation negatively affected flexural and tensile properties.

Use of phase change materials in wood and wood-based composites for thermal energy storage: A Review

Using phase change materials (PCMs) is an efficient solution for reducing energy consumption in buildings. These materials have a large capacity for storing thermal energy, making them an appealing option for energy management purposes. Phase change materials have been successfully incorporated into various construction materials such as concrete, brick, or plaster. The primary objective of this review is to examine previous studies conducted on the application of PCMs in wood. The initial section presents an overview of the direct impregnation techniques utilized for wooden materials. This is followed by a discussion on the implementation of macroencapsulated PCMs in wooden structures that are typically present in residential buildings. In addition, the use of shape-stabilized PCM/wood composites, preventing potential leaks during the phase change transition, is explored. Finally, patents related to the use of PCMs in wood are described. Future challenges include the incorporation of PCMs into wood composites to improve their thermal properties. This literature review shows that there is a gap in knowledge regarding the utilization of phase change materials in wood-based panels such as oriented strandboards, fiberboards, and particleboards. This provides an opportunity for future research to improve the performance of the products manufactured by the wood-based panels industry.

An energy storage composite using cellulose grafted polyethylene glycol as solid–solid phase change material

AbstractPhase‐change material (PCM) has great thermal energy ability, which has been used as building material for energy conservation. While the most widely used solid–liquid PCM usually appeared leakage during the phase change transition. In order to overcome the leakage of solid–liquid PCM and prepare a viable building energy‐saving materials for indoor temperature regulation, thermal energy storage composites were prepared by utilizing cellulose grafted PEG as phase change material (PCM) and high‐density polyethylene (HDPE) as the substrate. The liquid leakage of PEG was solved after graft to fabricate solid–solid PCM. HDPE is beneficial for solving the leakage and improving the mechanical property by its secondary encapsulation. The synthesized Cellulose‐PEG was characterized by scanning electron microscopy (SEM), X‐ray diffractometer (XRD), and differential scanning calorimetry (DSC). Thermal and mechanical characteristics of the composite were explored. The outcomes revealed that: (1) PEG was successfully grafted to the surface of cellulose and Cellulose‐PEG showed solid–solid phase change behavior. (2) Both the melting‐cooling temperatures and the thermal stability of solid–solid wood plastic composite (SSWPC) had the potential as thermal energy storage material for temperature regulating. (3) The addition of Cellulose‐PEG adversely affected moisture resistance, flexural property, and impact strength due to the weak interface bonding. The physical and mechanical degradation was tolerable for applying situation where mechanical performance is less crucial.Highlights Cellulose‐PEG showed solid–solid phase change behavior without liquid leakage. High‐density polyethylene (HDPE) was used as the matrix to realize the second encapsulation of PCM. Cellulose‐PEG negatively influenced the physical and mechanical property of HDPE. Solid–solid wood plastic composite presented great thermal storage capacity for indoor temperature regulating.

Synergistic enhancement of phase change materials through three-dimensional macropore lamellar structured MOF/EG composite for solar energy storage and beyond

The concept of high energy storage density, negligible changes in volume and pressure after phase change, approximately constant operating temperature and non-toxic of solid–liquid phase change energy storage are very appealing properties that makes it a good strategy to store heat. However, leakage and single thermal energy storage function has become a bottleneck for the further advances of long-term thermal stability and multifunctionality. It is reassuring to know that Metal-organic frameworks (MOF)-porous carbon materials can offer a solution to continuity challenge for growing demand for multifunctionality in phase change materials (PCMs). Herein, a phase change material (PCM) composite with good shape stability, thermal conductivity, and photothermal conversion capability was designed. EG in the blended system can effectively prevent the agglomeration of ZIF particles while simultaneously providing a high specific surface area and pore volume for the adsorption of paraffin wax. The as-obtained PCM composite possesses a 3-fold enhancement in thermal conductivity, 95.56% photothermal conversion efficiency, and excellent shape stability. It demonstrates the potential of MOFs-enhanced PCM composites for thermal energy storage and highlight the importance of synergistic or hybridization strategies in the development of advanced materials for sustainable energy applications.

Effects of expanded graphite on NaNO3/semi-coke ash shape-stable phase change composites for thermal energy storage

As an alkaline industrial solid waste with a porous structure, semi-coke ash can have adverse effects on the environment if accumulated or buried in large quantities. The research group has previously used this material in combination with NaNO3 to prepare a shape-stable phase change composite. Building upon the previous research team, this work manufactured the shape-stable phase change composite by cold-compression hot-sintering method using NaNO3 as the phase change material, semi-coke ash as the skeleton material and an innovative addition of expanded graphite as the thermal conductivity enhancer to enhance thermal conductivity of phase change material. Then, key thermal performance, mechanical strength, chemical compatibility, microscopic morphology, economic efficiency and emission reduction capacity were investigated. Results demonstrated that the sample SS2 with 0.5 wt% expanded graphite performed best, which also presented a mechanical strength of 113.82 MPa, a thermal conductivity of 1.844 W/(m·K), and an excellent thermal energy storage density of 424.91 J/g between 100–400 °C; Both the thermal performance and mechanical strength of sample SS2 decreased to some extent after the heating/cooling cycles; The semi-coke ash, expanded graphite, and NaNO3 showed excellent chemical compatibility while both the thermal energy storage cost (0.022 ¥/kJ) and the raw material carbon emissions (1041 kg) of producing per ton sample SS2 in this work were far below traditional shape-stable phase change materials.

Achieving extraordinary thermal stability of salt hydrate eutectic composites by amending crystallization behaviour with thickener

Commercial thermal energy storage (TES) systems necessitate reliable thermal performance throughout their operational lifetime. Repeated volume changes of the phase change materials (PCMs) during thermal cycling disengages thermal contacts between the conductive fillers like expanded graphite (EG) in TES composites, causing unstable thermal conductivity (k) that fades with cycling. Our in-operando crystallization studies on eutectic PCM made of zinc nitrate hexahydrate (ZNH) and KNO3 revealed that the thermal stability of PCM composites can be considerably degraded by the formation of large and sharp-cornered PCM crystals during the freezing cycle. While the crystals can push EG particles, disengaging thermal contacts between them, we have newly discovered that carboxymethyl cellulose (CMC) can be used to retain the thermal contacts by forming networks of smaller PCM crystals. Furthermore, the scalable synthesis methodology of EG/ZNH eutectic composites was introduced. Here EG particles were strongly connected into a matrix via a stable, corrosion resistant polydimethylsiloxane (PDMS) binder, stabilizing thermal networks and thereby maintaining k up to 1000 melt/freeze cycles. The thermal conductivity of our 25 vol% EG sample (13.3 W m−1 K−1) is more than 48% higher than other salt hydrate eutectic composites reported in the literature. We expect this study to provide insights on cooperative interaction between different components of TES systems (PCM, filler, thickener, binder) for exceptionally robust thermal properties.

Preparation of 3D BN-BT/PVDF skeleton structure composites for high thermal conductivity and energy storage

To obtain high energy storage dielectric materials with high thermal conductivity for electronic devices, we designed and constructed three-dimensional (3D) BN-BT/PVDF skeleton structure composites based on the ice template method and freeze-drying technology. Phonon thermal conductivity and intrinsic thermal conductivity can be improved by the hexagonal boron nitride (h-BN) thermal conductive skeleton orientation along the ice crystal on nanoscale. The 3D BN-BT/PVDF skeleton structure composites with high thermal conductivity and high energy storage can be obtained by impregnating the barium titanate (BT) modified polyvinylidene fluoride (PVDF) precursor into a 3D thermal conductive skeleton. When the h-BN content is 25 wt%, the comprehensive performance of BN-BT/PVDF composite are the most excellent with the energy storage density of 2.6355 J/cm3, which is 5.64 times of pure PVDF, and the thermal conductivity can reach 0.302 W/(m·K), an improvement of 152%, showing a promising industrial application prospects.

Waste polyvinyl chloride derived latent thermal energy storage composites for waste heat recovery via packed bed system

Latent thermal energy storage (TES) techniques utilizing phase change materials (PCMs) provide a promising way to mitigate the discrepancy between the intermittent nature of solar energy supply and consistent demand for human society. However, the development is hindered by the slow charging/discharging rates of the low thermal conductivity PCMs. Meanwhile, the high value-added utilization of waste plastic is receiving increasing attention as an environmentally sustainable strategy. In this regard, waste polyvinyl chloride (PVC) is recovered as SiC skeletons to obtain green phase change composites (PCCs) for waste heat recovery. After being infiltrated with paraffin wax (OP44E), proposed PCCs demonstrate a high retention ratio of latent heat up to 91.1% and a thermal conductivity of 2.4 W·m−1·K−1, which is benefitted from limited expansion and impurity remove process, respectively. With the elevated thermal conductivity and spectral absorptance, proposed PCCs exhibit superior solar-thermal energy storage rates. Furthermore, numerical simulation of the thermal charging/discharging performance and flow characteristics is carried out for the packed bed TES system. The results reveal a reduction in charging and discharging time by 21% and 41.1% for proposed PCCs, respectively. This work introduces a novel strategy for recycling waste heat via high-performance TES and repurposing waste plastics simultaneously.

Development of paraffin wax & used cooking oil based composite thermal energy storage for efficient potable water generation in a solar distillation unit

The purpose of this study is to develop a novel composite thermal energy storage system (CTESS) using blends of used cooking oil (UCO) and paraffin wax (PW) and experimentally investigate its effect on the performance of solar still for effective seawater desalination. The CTESS was developed by mixing UCO with PW in various volume ratios and the volume ratio of UCO and PW was optimized at 1:1. The objective was to examine the performance of the solar still with used cooking oil and paraffin wax (SSUCO) and compare it with a conventional solar still (CSS) without any energy storage. The investigation was carried out experimentally, and the results show that the SSUCO significantly enhanced freshwater production compared to CSS. On the first day, the overall freshwater production from SSUCO and CSS was found to be approximately 2870 ml/m2 and 1830 ml/m2, respectively, whereas, on the second day, it was about 2680 ml/m2 and 1750 ml/m2. The productivity of SSUCO increased by 56.83 % and 53.14 % on day 1 and day 2, respectively. The thermal efficiency of SSUCO on day 1 and day 2 was found to be 45.52 % and 41.67 %, respectively, whereas, for CSS, it was 29.03 % and 27.21 %. Economic analysis showed that the cost per litre of yield and payback period for SSUCO was reduced by 40.54 % compared to CSS. Moreover, the environmental analysis revealed that the carbon credit gained by SSUCO was 64.2 % higher than that of CSS. The results indicate that CTESS is a highly promising technique for seawater desalination in solar stills. It provides notable advantages such as increased productivity, enhanced thermal efficiency, and significant economic and environmental benefits.

MXene reconciles concurrent enhancement of thermal conductivity and mechanical robustness of SiC-based thermal energy storage composites

Latent heat thermal energy storage techniques based on phase change materials (PCMs) play a vital role in efficient and stable utilization of intermittent solar and thermal energy sources. However, low thermal conductivity and poor mechanical strength are daunting bottlenecks of traditional PCMs, inhibiting their wide applications. Here, we successfully enhance both thermal conductivity and mechanical robustness of porous SiC-based composite phase change materials (CPCMs) via doping MXene into SiC skeletons, which are superior to state-of-the-art ceramic CPCMs. The thermal conductivity of MXene-doped CPCMs achieves 15.21 ​W/(m·K) at a porosity of 72.9%, which is 25% higher than that of undoped counterparts. The underlying mechanism lies in that the oxide layer on the surface of MXene melts at a high temperature, filling the gap between SiC grains and optimizing the thermal transport path. Compared with virgin SiC skeletons, the flexural strength and compressive strength of MXene-doped skeletons are enhanced by 20% and 29%, respectively. This is because MXene removed from the oxide layer disperses in the ceramic matrix and improves the mechanical strength of the composite through pull-out, crack deflection and the change of fracture mode. Superior cycle stability and thermal shock resistance are also demonstrated. High thermal conductivity, robust mechanical strength, exceptional stability, and high solar absorptance enable prepared composites to realize high-performance dual-functional thermal and solar energy storage.

Mechanical and Thermal Characterization of Phase-Change Material and High-Density Polyethylene Functional Composites for Thermal Energy Storage

AbstractPhase-change materials (PCMs) can be used to develop thermal energy storage systems as they absorb large amount of latent heat nearly at a constant temperature when changing phase from a solid to a liquid. To prevent leakage when in a liquid state, PCM is shape stabilized in a polymer matrix of high-density polyethylene (HDPE). The present research explores the injection-molded mechanical and thermal properties of different PCM/HDPE composite ratios. The tensile strength and modulus of elasticity at room temperature and with the PCM fully melted within the composite are measured. Additionally, the hardness, latent heat of fusion, phase-change temperature, and thermal conductivity are investigated. An analysis of microstructures of the composite is used to support the findings. The PCM within the PCM/HDPE composite gives it the benefit of thermal storage but causes a decrease in mechanical properties.

Thermo-mechanical properties of a novel carbon fiber modified self-encapsulated PEG/sulphoaluminate cement-based thermal energy storage composite

In order to synergistically enhance the thermo-mechanical properties of cement-based thermal energy storage composites (TESC), a novel carbon fiber modified self-encapsulated PEG/sulphoaluminate cement-based thermal energy storage composite (CF-PSTESC) was developed using polyethylene glycol (PEG), sulphoaluminate (SAC) and carbon fiber (CF) as the phase change material (PCM), matrix material and modified material separately in this study. The thermal and mechanical performances of CF-PSTESC and their coupling effects were investigated and analyzed using differential scanning calorimetry, mechanical strength test, transient planar heat source method and microstructural analysis. The results show that PEG can be effectively encapsulated in the hydration products of SAC, but it will change the phase change temperature of PEG somewhat. Moreover, the thermal conductivity of CF-PSTESC improved as the CF content grew, which improved by 4.1% and 15.1% at 10 °C and 30 °C, separately, at a CF content of 1.00 wt%. Furthermore, the introduction of CF showed a remarkable influence on the mechanical strength enhancement of CF-PSTESC as confirmed by the experimental results. The compressive strength and flexural strength of CF-PSTESC were increased by 64.9% and 65.7%, separately, when the CF content was 1.00 wt%. Based on the above research results, the CF-PSTESC prepared in this study is a promising TESC.

Bio-based poly (lactic acid) shaped wood-plastic phase change composites for thermal energy storage featuring favorable reprocessability and mechanical properties

Bio-based poly (lactic acid) shaped wood-plastic phase change composites for thermal energy storage featuring favorable reprocessability and mechanical properties

A novel form stable phase change material with comb-like cross-linked polyurethane as supporting skeleton

To improve the homogeneity of phase-change materials (PCMs) composites for thermal energy storage, the poly(ethylene glycol monomethyl ether)-based trimethylolpropane (Ymer-N120) with long side ethyoxyl chains is employed to form comb-like polyurethane which functioned as supporting materials for PCMs. And the results of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, differential scanning calorimetry, accelerated thermal cycling testing, thermogravimetric analysis and field emission scanning electron microscopy (FESEM) suggested a crosslinked polyurethane embedded with micron grade myristic acid (MA) crystals was prepared during the thermal curing process. The obtained comb-like polyurethane (YP) can provide 3D structure supporting materials for melting MA. And the long side ethyoxyl chain of Ymer-N120 promote the melting MA form micron-sized crystals. The results of thermal reliability testing confirmed the advantages of same methylene groups in side chains and suggested the maximal hold capability of YP crosslinks is about 50 wt% of composites. With the 50 wt% addition of MA, YPM50 can supply high latent heat (over 90 J/g of YPM50) with fine thermal stability (due to its initial decomposing temperature reaches 190 °C) without leakage (after 500 times of accelerated thermal cycling testing). All results indicated this structure supplies an effective solution for the leakage of PCMs, which show a promising application in TES.

Cobalt phosphate-based composite with wall care putty as building envelope material for thermal energy storage

The four different thermal energy storage composites were synthesized by charging Co3(PO4)2·xH2O with wall care putty (Korean make) in aqueous media. These four different composites are abbreviated as A1, A3, A4 and A5 having composition 0.46 %, 1.00 %,1.63 % and 2.22 % of Co3(PO4)2·xH2O, respectively. Differential Scanning Calorimeter (DSC) was used to measure specific heat capacity (CP) for all above composites. Among all composites, the CP = 1.34 Jg-1K−1 is found maximum for composite A5 at 339 K in N2 atmosphere. The highest heat storage density is also observed, 80.95 ∼ 88.83 kJ kg−1, for composite A5 in temperature range 336 K to 342 K for storing heat up to ∼ 13 min. The optical band gap (Eg) is calculated using Tauc and Menth as well as Kubelka-Munk function for all composites and all found insulator. The calculated crystallite size of composite A3 is ∼ 400 nm.