Suitable Phase Change Temperature Research Articles

Bio-based eutectic composite phase change materials with enhanced thermal conductivity and excellent shape stabilization for battery thermal management

Organic phase change materials (PCMs) are commonly used for battery thermal management. Organic petroleum-based PCMs such as paraffin have an adverse effect on environment. Fatty acids as environmentally friendly bio-based PCMs, have enormous potential in sustainable development strategies. Nevertheless, the application of fatty acids in battery thermal management (BTMS) is restricted by the leakage of liquid PCM, poor thermal performance and the improper phase change temperature. We proposed a novel bio-based eutectic composite phase change materials (CPCM) with enhanced thermal conductivity and excellent shape-stabilization, composed of ethylene-vinyl acetate (EVA), Aluminum nitride (AlN), and the eutectic PCM of Lauric acid (LA) and Stearic acid (SA). Significantly, the screened eutectic PCM of LA-SA possesses a suitable phase change temperature(37.03 °C) corresponding to the battery operating temperature, and long-term thermal cycling stability of up to 100 cycles. And the cross-linked structure of EVA effectively encapsulated the eutectic PCM, whose mass only lost below 4% after being heated at 80 °C for 24 h. Simultaneously, the introduction of AlN can greatly improve their heat transfer ability and mechanical properties. LA-SA/EVA/AlN composites with 5 wt% AlN has adequate latent heat of 107.94 J.g−1 and high thermal conductivity of 0.726 W.(m·K)−1 as well as with low flexural strength of 1.72 MPa. Additionally, the proposed CPCM with 5 wt% AlN achieved the maximum temperature of battery below 45 °C during 4C discharging test. It suggested that the CPCM incorporated with AlN is capable effective cooling battery and dissipate energy inside PCM rapidly.

Shaped ionic wood for enhanced phase change performance

Wood with a porous structure is the best carrier for phase change energy storage materials, which can effectively prevent material leakage during thermal cycling and ensure its shaping effect. In this work, natural poplar wood was treated with delignification and then oxidized by TEMPO as a thermal energy storage matrix. Then, it was immersed in a solution of ethanol as the solvent, polyethylene glycol (PEG) and calcium chloride as the solutes, obtaining phase change energy storage ionic wood (DTW-PCMs). The results showed that the phase change energy storage material PEG-CaCl2 was successfully impregnated into the pore structure of wood; calcium chloride was effectively combined with –COOH in TEMPO oxidized wood for intermediate bonds and formed white complex crystals with PEG2000. The maximum absorption rate and differential scanning calorimetry (DSC) test results showed that TEMPO-oxidized poplar had a maximum absorption rate of 95.26% for PEG2000-CaCl2. Additionally, TEMPO-oxidized poplar exhibited good phase transition performance and suitable phase change temperature. The latent heat of phase transition was 86.96 J/g. Thus, the novel DTW-PCMs displayed a high potential application in the field of thermal energy storage and temperature regulation.

Adjustable temperature and high thermal conductivity composite phase change material based on sodium acetate trihydrate–alanine/expanded graphite for thermal management of electronic devices

Phase change energy storage technology using phase change materials (PCMs) is a viable solution to effectively address the heat dissipation problems of electronic devices. Herein, we proposed to prepare a modified PCM using CH3COONa·3H2O (SAT) as main PCM, 9 wt% DL-Alanine (DL) as temperature modifier, and 2 wt% Na2HPO4·12H2O as nucleating agent. Calculations using density functional theory method confirmed that the adjustment of DL on phase change temperature of SAT was originated from the hydrogen bond between them. Then, the modified PCM was loaded into 14 wt% expanded graphite (EG) to obtain a composite PCM with a suitable phase change temperature of 52.9 °C, phase change enthalpy of 227.4 J/g as well as supercooling degree of 6.6 °C, and the thermal conductivity of the composite PCM was as high as 11.52 W·m−1·K−1. SEM and pore structure analyses showed that the modified PCM was successfully loaded into the pore structure of EG, and their combination was verified by XRD and FT-IR as a physical interaction. After 200 heating–cooling cycles, the phase change temperature and enthalpy of the composite PCM was basically unchanged along with consistent crystal structure and chemical composition, showing an excellent thermal reliability. A comparative analysis applied in a testing system showed that with loading of the composite PCM temperature control module, the critical time of the electronic chip was extended by 4670 s and the thermal equilibrium temperature was decreased by 20.4 °C, presenting a good thermal management performance. Therefore, the prepared composite PCM had great potential for application in thermal management of electronic devices.

Composite energy storage cement-based mortar including coal gasification slag/paraffin shape-stabilized phase change material: physical, mechanical, thermal properties

Using renewable sources to generate energy is an approach to realize a sustainable energy system. Utilizing gasification slag, a solid waste from the coal gasification process, as a porous material not only substantially increases the value of the waste but also enhances thermal performance. This study develops a novel shape-stabilized coal gasification slag/paraffin (CGS-P) phase-change material for use in cement mortar to reduce indoor temperature fluctuations. Using a simple impregnation method, paraffin is incorporated into porous coal gasification slag to produce CGS-P. Coal gasification slag containing 30 % paraffin (CGS-P(30 %)) can maintain its structure without leakage at 60 °C. The thermal and chemical characteristics as well as the specific surface area of CGS-P(30 %) are characterized via X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, Brunauer–Emmett–Teller (BET) analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM)–energy-dispersive X-ray spectroscopy. The results of XRD and FT-IR analyses indicate that CGS-P(30 %) is a combination of paraffin and CGS, with no new substances formed. Furthermore, the BET, SEM, and TGA results confirm that the pores in CGS can effectively encapsulate approximately 30 % paraffin and that CGS-P(30 %) exhibits good thermal stability. The DSC analysis results show that CGS-P(30 %) has suitable phase-change temperatures and latent heat (18.02 °C and 59.30 J/g, respectively, during the endothermic phase). Furthermore, incorporating 30 % CGS-P(30 %) into the cement mortar (CESCM30) results in good mechanical and thermal performance. Particularly in hot climates, CESCM30 can notably reduce indoor temperatures, alleviate indoor cooling energy consumption, and indirectly reduce CO2 emissions. Therefore, CGS derived CGS-P is a promising material for accommodating solar thermal energy.

Thermo-Regulated Cotton: Enhanced Insulation through PVA Nanofiber-Coated PCM Microcapsules

The innovative integration of phase change materials (PCMs) into textiles through microencapsulation presents a transformative approach to developing thermally regulated fabrics. This study explores the synthesis and characterization of microcapsules containing a coconut oil core and an ethylcellulose shell, and their application on cotton fabrics coated with polyvinyl alcohol (PVA) nanofibers. The dual-layer system involving microcapsules and nanofibers is designed to enhance the thermal insulation properties of textiles by regulating heat through the absorption and release of thermal energy. The microencapsulation of PCMs allows for the effective incorporation of these materials into textiles without altering the fabric’s inherent properties. In this study, the coconut oil serves as the PCM, known for its suitable phase change temperature range, while ethylcellulose provides a robust shell, enhancing the microcapsules’ structural integrity. The application of a PVA nanofibers layer not only strengthens the thermal regulation properties but also protects the microcapsules from release while the fabric is manipulated, thereby prolonging the functional life of the fabric. Comprehensive testing, including scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), confirms the successful application and durability of the microcapsules on the textiles. Thermal imaging studies demonstrate the fabric’s enhanced capability to maintain a consistent temperature, highlighting the potential of this technology in applications ranging from smart clothing to energy-efficient building materials or automotive isolation. The integration of PCMs in textiles via microencapsulation and nanofiber technology marks a significant advancement in textile engineering, offering new opportunities for the development of smart and sustainable materials. The study demonstrates the promising potential of integrating PCMs into textiles using microencapsulation and nanofiber technologies. Despite the initially modest insulation improvements, the methodology provides a robust foundation for further research and development.

Disodium hydrogen phosphate dodecahydrate/fumed silica composites with high latent heat and suitable phase change temperature for use in building roof

Introducing phase change materials (PCM) with suitable phase change temperature and large latent heat into the application of building roofs is conducive to building energy efficiency, which can reduce indoor temperature fluctuation and improve thermal comfort. In this paper, the optimized disodium hydrogen phosphate dodecahydrate (DHPD) was combined with fumed silica (FS) to prepare a new type of DHPD/FS composites, with a phase change temperature of 41.5 °C, a latent heat of change of 103.46 J/g, and an optimal content of 22.5 % of FS. The leakage experiments proved that there was no leakage of the PCM at this ratio, and after 200 cycles of thermal cycling, the phase change temperature of DHPD/FS composites basically remains unchanged, with good thermal reliability, but the addition of FS will make the material decrease in thermal conductivity, and the thermal conductivity is reduced to 0.19 W·m−1·K−1. Furthermore, the study investigated the application of the encapsulated DHPD/FS composites as a phase change board on the roof. The results indicated that the inclusion of the phase change board improved indoor thermal comfort and demonstrated good thermal performance. When the phase change board was positioned in the top layer, the enhancement of thermal comfort was most optimal.

Preparation and Photothermal Properties of Accordion‐Like MXene/Sodium Acetate Trihydrate Composite Phase Change Materials

Phase change materials (PCMs) are promising options for thermal energy storage. Combining sodium acetate trihydrate (SAT) with MXene, the composite phase change materials (CPCMs) have been prepared. The surface morphology, thermal storage performance, and solar energy photothermal conversion efficiency of the CPCMs with various MXene contents are analyzed. According to the microstructure morphology analysis, MXene is accordion‐shaped, and tightly associated with SAT. Differential scanning calorimetry measurement results show that CPCMs possess high latent heat and suitable phase change temperature for the applications of solar heat storage. The absorption wavelength range of SAT/MXene is extended from 200–258 nm to 200–497.7 nm with a photothermal conversion efficiency of 81.3%. SAT/MXene‐2%, SAT/MXene‐8%, and SAT/MXene‐14% have thermal conductivities of 0.84, 1.14, and 1.47 W/ (m · K), respectively, which are higher by 44.9%, 96.6%, and 153.4% than 0.59 W/ (m · K) of pure SAT. CPCMs exhibit excellent thermal stability and reliable cycling stability after 50 cycles, which show that MXene can prevent leakage during the solid‐liquid phase transition process. The expansion of PCM's practical applicability and MXene/SAT composites with good photothermal characteristics create a theoretical foundation for the effective use of renewable energy sources.

Thermal Properties and Characterization of n-Decanol-Capric Acid/Expanded Graphite/Boron Nitride for Thermal Energy Storage

To find a low temperature phase change material (PCM) that can be applied to the middle constant temperature chamber of the three chamber refrigerator, this study proposes a binary eutectic PCM of n-decanol and capric acid as a base liquid, expanded graphite as a support material, and boron nitride as a thermal conductivity enhanced particle to modify the material. The composite PCM with suitable phase change temperature and high phase change latent heat is prepared by the solution blending method. The leakage rate experiment determines the maximum adsorption ratio of expanded graphite to be 92 %. The chemical structure, microstructure and thermodynamic properties are characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, thermal conductivity analyzer and thermogravimetric analyzer. The results show that the n-decanol and capric acid binary eutectic PCM is fully wrapped in the porous structure of expanded graphite, and boron nitride thermal conductivity enhanced particles are well adsorbed on the surface and pores of expanded graphite. The n-decanol and capric acid phase change material, boron nitride thermal conductivity enhanced particles and expanded graphite support material are only physically combined and no chemical reaction occurred. The phase change temperature of CPCM-2 with 3 % boron nitride thermal conductivity enhanced particles is -3.68 °C, the phase change latent heat is 129.2 J/g, and the thermal conductivity is 0.75 W/m·K. It has good thermal stability and reliability in the application temperature range.

Hydrogel-stabilized supercooled salt hydrates for seasonal storage and controlled release of solar-thermal energy

Seasonal storage of solar-thermal energy within salt hydrate phase change materials (PCMs), which are known for their large latent heat capacity, suitable phase change temperature range and cost-effectiveness, has garnered...

Form-stable phase change composites with multistage pores based on black phosphorus nanosheets/PVA aerogel for efficient solar photothermal conversion

The development of the form-stable Phase Change Materials (FPCMs) with excellent solar-thermal conversion performance is crucial for sustainable solar energy utilization. However, the leakage of organic phase change materials limits its practical application. Herein, we reported a novel multistage porous aerogel fabricated from black phosphorus (BP) nanosheets, polyvinyl alcohol (PVA) and carbonized kapok (CK) fibers by a solution blending method. The aerogel was directly dipped in molten hexadecanol as the phase change material. The results showed that the HD/PVA-BP30 had a phase change temperature of 55 °C, latent heat of phase change of 164.3 kJ/kg. After 100 melting/freezing cycle, the phase change composite leaks only 0.38 %. The mechanical properties of PVA-BP30 exhibited a compressive strength of 1.04 MPa at 80 % strain, and the mechanical strength of the aerogel increased with increasing BP content. The addition of BP also enhanced the photothermal conversion (73.6 %) under 1 sun illumination. The prepared HD/PVA-BP30 have the characteristics of the suitable phase change temperature, excellent melting/freezing cycle reliability, strong mechanical properties, and anti-leakage properties. Therefore, the reported FPCMs are anticipated to have great potential for solar water heater utilization in bath water.

Biomimetic design of flexible wood film combined with thermochromism and self-luminescence for enhanced energy-saving

In this research, the layered bionic wood films were designed and constructed inspired by the “reinforced concrete”-like chemical structure of wood combined with the macrostructure of bark and phloem. Specifically, a simple strategy for immobilizing diol eutectic phase change components with intelligent discoloration/chromogenic leaching in wood by using delignification wood (DE) with capillary penetration was adopted. The “reinforced concrete” structure solves the problem of easy leakage and weak strength due to strong molecular bonding. The bionic wood film has a high phase change enthalpy (155.5 J/g) and suitable phase change temperature (29.9 °C). On this basis, combined with PVA/glycerol as a flexible matrix as the inner bark of wood and phloem connecting each layer, combined with PVA/glycerol/PLO-8C as a key self-luminescent energy-enriched material as the outer bark of wood, the flexible and self-luminescent energy-saving wood films were reconstructed in a biomimetic way with a high mechanical strength (65.53 MPa). Through the change of color, the phase transition process and the current ambient temperature can be intuitively judged. The surface morphology and luminescence intensity were also not affected after 50 cycles of absorption and luminescence. This study provides a broader development direction for the application of intelligent enhanced energy enrichment of PCM-based on bionic wood construction.

Myristic acid-tetradecanol-capric acid ternary eutectic/SiO2/MIL-100(Fe) as phase change humidity control material for indoor temperature and humidity control

Building materials with the dual function of temperature and humidity regulation can improve people's living comfort and reduce energy consumption. In this work, a simple and convenient strategy for building a comfortable indoor temperature and humidity environment was proposed. The phase change humidity control material (PCHCM) was prepared by the mixing of form-stable composite phase change material (CPCM) as temperature-control component and hygroscopic MIL-100(Fe) as humidity-control component. In PCHCM, the CPCM was obtained by molten recombination of myristic acid, tetradecanol, and capric acid (MA-TD-CA) as phase change material and hydrophilic fumed silica (SiO2) as porous carrier, and MIL-100(Fe) was synthesized by low-temperature solution method. Thermal analysis indicated that, under the optimized mass ratio of 28.8%MA-61.2%TD-10%CA, the CPCM containing 30 % SiO2 could effectively prevent the leakage of ternary eutectic, with a suitable phase change temperature and enthalpy (21.74 °C, 96.70 J·g−1). The thermal and wet performance evaluation confirmed that the PCHCMs containing 40–50 % CPCM had human body comfortable phase change temperature (26.96–27.26 °C) and high saturation adsorption capacity (0.179–0.205 g/g) at 60 % RH as well as outstanding thermal and wet cycle reliability, indicating the novel MA-TD-CA/SiO2/MIL-100(Fe) PCHCM has broad application potential in room temperature and humidity control and building energy conservation.

Effects of Polyethylene Glycol/Porous Silica Form-Stabilized Phase Change Materials on the Performance of Asphalt Binders.

The road performance and temperature-regulating properties of asphalt binders modified with novel polyethylene glycol (PEG)/porous silica (PS) form-stabilized phase-change materials (PEG/PS-fs-PCMs) were studied. PS and PEG were used as the supporting substance and PCMs. The results showed that PEG/PS-fs-PCMs could maintain a maximum weight percentage of 70% without leakage, at temperatures as high as 90 °C. The PEG/PS-fs-PCMs exhibited stable chemical structures, excellent thermal stability, high heat storage density, and suitable phase-change temperature. Based on conventional physical tests, the addition of PEG/PS-fs-PCMs can increase the viscosity and the degree of hardness of asphalt binders; thus, achieving an excellent comprehensive performance of the modified asphalt binder depends on determining the optimal dosage of PEG/PS-fs-PCMs. Additionally, incorporating PEG/PS-fs-PCM particles into the asphalt binder can enhance its ability to withstand permanent deformation at elevated temperatures, while PEG/PS-fs-PCMs mainly act as a filler, weakening the cohesive force of the asphalt molecules, and preventing the ductility of asphalt from expansion, according to DSR and BBR tests. Moreover, the use of PEG/PS-fs-PCMs can enhance the heat transfer properties of the asphalt binders, resulting in an improved temperature regulation performance. However, the accumulation of PEG/PS-fs-PCM particles on asphalt binders can negatively impact the storage stability of the modified asphalt binders, because of the difference in density between the two materials.

Review on PCM Heat Sink for Electronic Thermal Management Application

A significant challenge in thermal management has arisen as a result of the rising demand for high-performance electronic devices. The efficiency, size, and weight of conventional cooling methods like liquid and air cooling are constrained. Due to their high storage of latent heat capacity and isothermal phase transition behavior, phase change materials (PCMs) have become a promising thermal management solution. The purpose of this experimental study is to evaluate the performance of a PCM heat sink for electronic thermal regulation. The PCM heat sink is made up of a PCM module attached to a typical heat sink. To improve heat dissipation capabilities, the PCM module uses a PCM material with a suitable phase change temperature and encapsulation. The experimental setup involves simulating real-world operating conditions by applying controlled heat loads to electronic components. By observing temperature changes, thermal resistance, and transient response, the PCM heat sink’s thermal performance is assessed. To evaluate the superiority of the PCM heat sink, a comparison is made with traditional air-cooled and liquid-cooled heat sink configurations. The experimental investigation’s findings show that the PCM heat sink performs better in terms of thermal management than traditional cooling techniques. The phase change process used by the PCM efficiently absorbs and stores extra heat produced by electronic parts, improving temperature regulation and lowering temperature gradients. Lower component temperatures and higher operational reliability are the results of the PCM heat sink’s improved thermal resistance and heat dissipation efficiency. A further benefit of the PCM heat sink’s isothermal behavior during the phase transition is that it prevents temperature spikes and lessens the effects of heat stress on the electronic devices. The long cooling times provided by the PCM material’s high latent heat storage capacity allow for prolonged operation without affecting device performance. This experimental study concludes by demonstrating the efficiency of a PCM heat sink for electronic thermal management. The design of heat sinks with PCM integration offers notable enhancements in temperature control, thermal resistance, and system overall reliability. The results of this research help to advance thermal management strategies, which makes it easier to create efficient electronic devices with better cooling capacities.

Highly flexible phase-change film with solar thermal storage and sensitive motion detection for wearable thermal management

The utilisation of phase-change materials (PCMs) for the thermal management of wearable devices remains a significant challenge because of intrinsic leakage and rigidity issues. Therefore, this study develops a wearable phase-change film (FSPCF) that addresses these issues while providing high flexibility, superior solar thermal conversion efficiency and sensitive motion detection. The FSPCFs were fabricated using n-eicosane, vinyl-dimethylsiloxane, hydrosilicone oil and multiwall carbon nanotubes (MWCNTs) via salt-template-assisted and dip-coating methods. The interconnected 3D polysiloxane networks provided ample support for n-eicosane and effectively prevented liquid leakage during 500 thermal storage/release cycles. Increasing the amount of the deposited MWCNTs considerably improved the thermal conductivity of the FSPCF, from 0.314 W·m−1·K−1 (FSPCF-0) to 0.719 W·m−1·K−1 (FSPCF-1.2). The synthesised FSPCFs exhibited high thermal-energy-storage density (109.5–117.8 J/g), and a suitable phase-change temperature (about 36℃) for human thermal regulation and desirable thermal stability. Furthermore, FSPCF-added MWCNTs demonstrated excellent solar thermal conversion and storage efficiency (92.3%), making FSPCFs an attractive heat source for integration into wearable devices. Notably, the FSPCFs also demonstrated sensitive motion detection (GF = 46.3) and could monitor various human movements in real time, including curvature movements (bending of fingers, wrists, elbows, knees and neck), facial expressions and vocal vibrations. Overall, the developed film exhibits tremendous potential for use in the thermal management of wearable devices.

Developing a solid–solid phase change heat storage asphalt pavement material and its application as functional filler for cooling asphalt pavement

Currently, functional pavement materials become a research hotpot for road researchers. This paper aims to develop a phase change heat storage asphalt pavement material and then design phase change heat storage asphalt mixtures with active cooling ability. The synthesized polyurethane-based solid–solid phase change material (PUSSPCM) with suitable phase change temperatures, desirable thermal energy storage capacity and excellent phase change cycling stability can meet the active cooling demand of asphalt pavement. There are also excellent leakage resistance, volume stability and chemical stability that enable withstanding the harsh condition of asphalt pavement. Therefore, the PUSSPCM can be considered as a promising phase change filler. Subsequently, the phase change heat storage asphalt mixtures are prepared by the equal volume replacements of limestone filler with PUSSPCM. The replacements can improve the high-temperature stability and low-temperature cracking resistance whereas weaken the water stability of an asphalt mixture. When the replacement amount is no more than 40 vol%, the phase change mixtures can satisfy the pavement performance requirements. The replacements increase the heat absorption capacity but decrease the heat transfer rate, which leads to decrease in the temperature rising rate of the asphalt mixture with more PUSSPCM.

New energy-saving building developed by using polyethylene glycol/halloysite nanotube energy-storage blanket and heat-insulating glass with NaxWO3@SiO2 nano-coating

Transparent heat-insulation glass (HIG) with a highly selective light-absorbing coating and an energy-storage blanket (ESB) loaded with phase change materials show considerable potential in reducing building energy consumption. However, the energy-saving effect of a single material is usually not ideal, and the instability of HIG and ESB limits their applications. In this work, HIG with enhanced stability and a form-stable ESB was prepared. The temperature difference between various indoor areas and energy consumption were reduced simultaneously because of the temperature regulation function of the HIG and ESB in the light and dark areas. NaxWO3@SiO2-coated HIG showed excellent daylighting and near-infrared-light-shielding ability with visible light transmittance of 71% and near-infrared light transmittance of 16%, respectively. Moreover, polyethylene glycol/halloysite nanotube composite phase change material with a high enthalpy of 71.1 J/g and a suitable phase change temperature of 27.5 °C was prepared for the form-stable ESB. The test room experiment indicated that the combination of the HIG and ESB (HIG–ESB) reduced the indoor temperature difference from 6.8 °C to 0.9 °C and the maximum temperature by 33–40%. The energy consumption simulation revealed that the ESB can save energy in all selected cities, whereas HIG is only applicable to cities in warm regions. HIG–ESB achieved the highest annual energy-saving rate of 43.9% in Hong Kong. The joint application of the HIG and ESB provides a new strategy for developing passive energy-saving buildings.

Experimental investigation on high energy-density and power-density hydrated salt-based thermal energy storage

• High energy and power density hydrated salt-based TES device. • Performance evaluation of TES device at different conditions for hot water heating. • Phase-change temperature of 50 ℃ and phase-change enthalpy of 184.5 kJ·kg −1 . • Energy storage density is 2.6 times higher than that of conventional water tank. • High energy storage density (∼88.4 kWh·m −3 ) and high power density (669.9 W·kg −1 ) Thermal energy storage based on phase change materials (PCMs) plays a key role in bridging the gap between energy supply and demand for renewable energy applications. Hydrated salt is one kind of the most promising PCMs due to high phase-change enthalpy, non-flammability and low cost. Herein, we design and fabricate a lab-scale high energy-density and power-density thermal energy storage (TES) device using hydrated salt-based phase change composite (PCC). The thermophysical properties of the hydrated salt-based PCC are characterized and the thermal performances of the PCC-based TES device are analyzed at different operating conditions during charging and discharging processes. The Differential Scanning Calorimeter (DSC) analysis shows that the PCC has high phase-change enthalpy of 184.5 kJ·kg −1 and suitable phase-change temperature of 50 ℃ for hot water heating. The experimental results show that the PCC-based TES device exhibits high specific energy storage density up to 88.4 kWh·m −3 , approximately 2.6 times higher than the conventional water tank storage device. In discharging process, the PCC-based TES device exhibits high energy density (∼81.6 kWh·m −3 ), high efficiency (∼92.3 %), high power density (∼669.9 W·kg −1 ), and stable output hot water temperature (45 ∼ 47 ℃) at different water flow rates (0.42 ∼ 2.42 L·min −1 ) and inlet cold water temperatures (8 ∼ 25 ℃).

Calorimetric study of carbon dioxide (CO2) hydrate formation and dissociation processes in porous media

Understanding the formation and dissociation mechanisms of gas hydrate in porous media is important for the development of new energy-efficient and environmentally friendly technologies related to cold storage as they provide significant latent heat and energy density at suitable phase change temperature. The challenge is to understand the interactions between gas hydrates and the chosen storage media in order to assess the operating conditions likely to optimize time and energy consumption in cold production and storage systems. In this work, CO2 hydrates formation and dissociation are investigated in two morphologically different porous materials: sand and silica gels. A calorimetric approach is applied to study both the CO2 hydrate formation kinetics, particularly the induction time, and the amount of hydrate formed for each of the two porous materials. The experiments are performed using a differential thermal analysis device with two identical measuring cells. The present work is focused on assessing the effect of key factors like water saturation, particle size and the morphology of porous media on CO2 hydrate formation and dissociation processes. Overall, the results do not show a statistically significant correlation between these factors and the induction time. Interestingly, the results obtained with dual porous silica gel showed a higher amount of hydrate formed compared to those with sand for similar initial pressure, temperature and water content conditions. This result may be due to the fact that silica gels provide higher surface area due to their smaller particle size (20–45 µm vs 80–450 µm for sand), and the presence of internal pore volume in silica gel particles.

In-situ copper ion reduction and micro encapsulation of wood-based composite PCM with effective anisotropic thermal conductivity and energy storage

This work develops metallic wood-based phase change materials (MWPCM) with high-performance anisotropic thermal conductivity by impregnating wood with phase change microcapsules and subsequent in situ chemical deposition of copper inside the wood cell lumen. Phase change material (PCM) is encapsulated by polymer to form phase change microcapsules, which solve the leakage problem effectively. Benefited with the well-aligned and hierarchical porous structure of wood, phase change microcapsules coated with copper layer are orderly confined inside wood vessels and fibers, developing a continuous and anisotropic heat transfer network along the highly oriented transport tissues of wood. The morphology, chemical structure and crystallization of microcapsules and MWPCM are investigated using scanning electronic microscope (SEM), flourier transformation infrared spectroscopy (FTIR) and X-ray diffractometer (XRD), and the thermal storage capacity, thermal stability and thermal conductivity of the developed PCM composites are examined using differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and laser flash diffusivity apparatus (LFA) respectively. The results show that PCM capsules were effectively accommodated in orderly porous wood as a carrier; the radial and longitudinal thermal conductivity of MWPCM reached 0.37 W/(m*K) and 0.53 W/(m*K), which increased by 362% and 211% compared to pure wood, respectively. The anisotropic thermal conductivity of MWPCM enabled an efficient heat transfer along the longitudinal direction and reduced the heat loss in the transverse direction. MWPCM exhibited good thermal energy storage capacity (92.9 J/g and 94.6 J/g) and suitable phase change temperature (11.4 °C and 29.4 °C) for indoor thermal energy management. MWPCM also displayed outstanding shape-stability, excellent thermal stability and temperature regulation, which has a great potential for building energy collecting, storage and management.