Application Of Phase Change Materials Research Articles

Enzymolysis-treated wood-derived hierarchical porous carbon for fluorescence-functionalized phase change materials

Dominating obstacles that currently obstruct the development and industrial application of phase change materials (PCMs) are their low thermal conductivity , high cost, easy leakage and poor mechanical performance. Our goal is to enhance the thermal conductivity and power capacity of PCMs as much as possible using abundant biomass-derived carbon as supports. Herein, cellulase is employed to efficiently hydrolyze segmental cellulose in wood to formulate luxuriant micropores , which contribute to sufficiently expose the interior of the wood to effectively construct luxuriant adsorption sites onto the carbon skeleton during the subsequent high-temperature pyrolysis process. The resulting wood-derived hierarchical porous carbon infiltrates polyethylene glycol (PEG) and sufficiently liberates crystallization via microscopic morphology regulation. The strategy assembles good mechanical performance, high energy storage capacity (151.74 J/g), anisotropic thermal conductivity and improved thermal stability. Furthermore, the composite PCMs loaded with carbon quantum dots (CQDs) integrate the dual advantages of fluorescent function and thermal energy storage , which provides the possibility for the application of enzymolysis-treated wood-supported composite PCMs in specific equipment.

Nano additive enhanced salt hydrate phase change materials for thermal energy storage

ABSTRACT Energy storage plays a vital role in sustainable development. Focus on energy storage using phase change materials (PCMs) are of current research hotspot due to high latent heat value. Nevertheless, poor thermal conductivity, supercooling, phase separation, corrosive nature of salt hydrate is of great concern. Distress related to properties of PCM is resolved using nano additives. Major research focus on the dispersion of nano additive with PCM depends on (a) technique of preparing a novel composite PCM; (b) improvement of their thermophysical characteristic; and (c) advanced application for human comfort without polluting the environment. This article presents a critical review of hybridization techniques of metal, carbon and polymer additives on salt hydrate PCMs. To facilitate researchers, the significant variation on thermophysical properties of salt hydrate with nano additives are vitally compared, analysed and critically reviewed. This review article also includes the advanced application of nano additives-based salt hydrate PCMs.

Role of phase change materials in backfilling of flat-panels ground heat exchanger

The behaviour of a multi-source heat pump system coupled with phase change materials (PCMs) is discussed in this manuscript, as based on selected data collected during one-year testing at the TekneHub Laboratory of the University of Ferrara (Italy), as a synergic prototype setup of two European projects: IDEAS, an H2020 project, and CLIWAX, an EFDR project. Three geothermal loops of novel shallow Flat-Panels ground heat exchangers (GHX) provide the coupling of a water-to-water heat pump with the ground, as backfilled with sand, a mixture of sand and granules with paraffins and containers filled in with hydrated salts. Furthermore, two hybrid photovoltaic panels and a dry-cooler complete the exploitable thermal sources landscape. Finally, a control unit manages all the elements for the exploitation of the different thermal sources. How the increased underground thermal energy storage is driven by PCMs has been investigated by means of specific tests, and compared with the standard case of backfilling sand. Results confirm that PCMs can compensate peak loads occurring during hard weather conditions. Good performances of the multi-source heat pump were found, with a winter coefficient of performance always higher than 5. Finally, the application of PCM in summer should be preferred in climatic zones with hot summers and cold winters, With evidence, latent heat, thermal conductivity and melting point of PCMs should be tuned accordingly to the energy requirements and the local ground thermal conditions.

Phase change material‐assisted freezing of tuna: Impact on freezing process and thawing loss

AbstractDue to slow freezing, freezing fresh fish in a chest freezer often leads to deterioration while products are thawed. Many approaches have been conducted to deal with it. One of them is the application of Phase Change Material (PCM) in refrigeration systems. This study aims to investigate the ability of PCM to accelerate the freezing of fish in the household freezers. The tuna used was stored in the freezer with PCM, which was put on a surface wall cabinet then compared with storage in the freezer without PCM. Besides, the door of the freezer was also opened frequently (three times a day, 1 hr each time) to find out the effect of fluctuating temperatures and freezing operations for 60 hr. The parameters observed include the evolution temperature of the air cabinet and fish, energy consumption of the freezer, and thawing loss. Results showed that PCM accelerated the cooling rate of air cabinets and fish but could not suppress the fluctuation temperature. The quality of the frozen tuna improved, which was indicated by a decreased thawing loss parameter from 3.10% to 1.76%. Overall, this finding revealed PCM has significant potential to improve the fish freezing process.Practical ApplicationsThe household chest freezer is widely used to freeze fish by small and medium‐sized enterprises (SMEs). The most important factors in freezer preferences are simple operations and low energy consumption. But, the freezer worked at slow freezing, which caused higher thawing losses of the product. Hence, the application of PCM to the household freezer potentially improves the freezing process of the fish. So, sellers and retailers of fish could maintain their products without replacing the freezer with an advanced one.

3D porous aerogel based-phase change materials with excellent flame retardancy and shape stability for both thermal and light energy storage

As we all known, the problems of easy leakage, poor thermal conductivity and high flammability will hinder the application of phase change materials for energy storage. In this work, a novel multifunctional composite phase change material was prepared via efficient modifications, which has preeminent flame retardancy and shape stability to achieve safe and efficient storage of heat and light energy. As expected, the composite phase change material had excellent thermal energy storage density (163.9 J/g), even the melting enthalpy ratio could reach 91.1%. In comparison with pure PEG, the thermal conductivity has realized improvement as well, and the shape stability of composite phase change materials was significantly promoted, which could be heated at 80 °C for 1 h without the leakage of PEG. In addition, it showed excellent thermal stability and fire resistance, the maximum decomposition rate and the peak heat release rate were decreased by 47% and 34.1%, respectively, compared with pure PEG. More importantly, composite phase change materials realized the storage of light energy on the basis of thermal energy management and utilization, which could absorb and store ultraviolet and visible light during the day, and then release fluorescence slowly for a long time in the dark. To sum up, neoteric multifunctional composite phase change materials have enormous prospects for safe and efficient application in the fields of solar energy acquisition, thermal and light energy storage and thermal management. • A novel multifunctional composite phase change material was designed. • The composite phase change material had excellent thermal energy storage density, thermal stability and fire resistance. • The maximum decomposition rate and PHRR were decreased by 47% and 34.1%, respectively, compared with pure PEG. • The composite phase change materials realized the simultaneous storage of heat and light energy.

Influence of phase change material (PCM) parameters on the thermal performance of lightweight building walls with different thermal resistances

Phase-change materials (PCM) can effectively improve the thermal performance of lightweight building walls (LBW), but their contribution efficiency is related to PCM parameters and the thermal resistance of the original walls ( R wt ). Therefore, a heat transfer model of LBW integrated with PCM was built and validated in this paper, and the influence rules and contribution efficiency of PCM parameters on the thermal performance of LBW with different R wt were analyzed and evaluated by numerical simulation. The results show that: (1) The suitable phase-transition temperature is more influenced by the PCM location and less by R wt , and the middle of wall and 22–32 °C is the best choice for PCM; (2) The PCM parameter values are not proportional to the improvement of thermal performance and its influences are more noticeable as the R wt decreased, and their optimal values and its contribution efficiency are diminished with R wt is boosted; (3) The PCM contribution efficiency is reduced by 56.61%(attenuation rate), −34.3%(delay time), 58.31%(peak heat flux) and 61.78%(average heat flux) as the R wt [(m 2 ·K)/W] is increased from 2.0 to 5.0 under the suitable PCM parameters. The findings provide data support and theoretical reference for the application of PCM in different types of lightweight buildings.

Insulated box and refrigerated equipment with PCM for food preservation: State of the art

The use of Phase Change Material (PCM) as a cold accumulator in refrigeration contexts leads to better food safety, food security and energy management. However, applying PCM in real usage still depends on the user's experience or a trial-and-error basis. Studies carried out on insulated boxes and in refrigerated equipment (refrigerated trucks, cold storage facilities, display cabinets and domestic refrigerators) were reported. The influence of the studied conditions such as PCM melting point, position, mass of PCM and load, insulation material, external temperature on air/product temperatures and energy consumption was analyzed. Important parameters enabling the application of PCM in boxes and refrigerated equipment are the wall insulation and PCM configuration cited previously. Because of the complex interactions between these parameters, they need to be considered together with the usage conditions. The relationships between heat exchange and airflow inside the equipment should be further studied notably in function to the PCM position. • PCM enhances quality preservation and energy management in food cold chains. • PCM efficiency is related to the insulation of the system and PCM configuration. • Current studies have shown the most efficient design for specific conditions only. • A numerical study may be useful for box design and use conditions.

Phase Change Materials with Enhanced Thermal Conductivity and Heat Propagation in Them

The review contains information o; n the properties of phase-change materials (PCM) and the possibilities of their use as the basis of thermal energy storage. Special attention is given to PCMs with a phase transition temperature ranging between 20 and 80 °C since such materials can be effectively used to reduce temperature variations in residential and industrial rooms. Thus, the application of PCMs in the construction industry enables one to considerably reduce the power consumption and reduce the negative environmental impact of industrial facilities. Thermophysical characteristics of the main types of PCMs are presented. The heat balance for a room with walls made of PCM-added materials is estimated. The calculations demonstrate that such structures can stabilize the temperature in practical applications as a result of the usage of such materials. The construction of a thermal accumulator on the basis of PCM is proposed and analyzed. This facility uses water as a working fluid and paraffin as a PCM. The thermal accumulator has a modular structure so that the number of similar modules is determined by the quantity of energy to be stored. The potential of wide application of PCMs as a basis for thermal energy storage is rather limited due to a very low conductivity (less than 1 W/(m K)) inherent to these materials. This drawback can be overcome by adding carbon nanoparticles whose thermal conductivity is four to five orders of magnitude greater than that of the matrix material. The problem of fabrication of polymer composites with enhanced thermal conductivity due to nanocarbon particles doping is discussed in detail.

Facile preparation of reversible thermochromic phase change materials towards temperature-controlled information storage and self-reporting

Phase change materials (PCMs) are extensively applied in thermal energy management in the recent years due to high latent heat and efficient energy utilization. However, the current studies of PCMs are mainly focused on the single function of thermal storage which greatly limits their advanced applications. Herein, we prepared novel reversible thermochromic phase change materials (TCFPs) consisting of thermochromic compound and filter paper via vacuum-assisted impregnation method. Based on the excellent reversible thermochromic ability, these designed TCFPs can achieve multiple functions, including temperature-controlled information storage and self-reporting along with the thermal storage ability. Taking advantage of the lightweight and flexibility of TCFPs can rapidly create arbitrary shapes, such as the quick response codes, achieving the concealment or exhibition of the information by thermal stimuli. Moreover, TCFPs modified by methyl red can possess a better visual effect and can helps to realize the temperature-controlled self-reporting. Our work demonstrates a facile design strategy of multifunctional TCFPs, unlocking opportunities for smart applications of PCMs.

Properties of PCM-based composites developed for the exterior finishes of building walls

Phase change materials (PCM) are widely known for their high thermal storage capabilities. They are generally utilized to increase the thermal mass of buildings’ lightweight materials, which improves their thermal performance and reduces the need for air-conditioning systems. PCM layers are commonly applied to the buildings’ interior parts, close to the indoor environment, which helps regulate the indoor temperature. However, few studies reported that PCM application on the exterior of the envelopes increases their thermal insulation, which can reduce the outdoor heat gain. Therefore, this study aims to develop PCM-based composites for the exterior finishes of building walls. To this end, microencapsulated PCM was integrated into the cement render and foamed concrete with different fractions. The developed composites were tested, evaluated, and compared to the composites without PCM integration. The results showed that PCM integration into foamed concrete reduced the density and thermal conductivity to 896 kg/m³ and 0.18 W/mK, respectively, i.e., lower by 50% and 86% compared to the conventional cement render. Besides, PCM integration added thermal energy storage of 38 J/g to the composite, which can improve its thermal mass. Although the compressive strength decreased by 53% with PCM integration into the cement render, it increased by 28–49.7% with PCM integration into foamed concrete due to PCM capsules substituting some of the air gaps. The findings of this study demonstrate a high potential of using PCM-based foamed concrete to produce lightweight cladding panels for building exteriors with improved thermal insulation and thermal mass to reduce external heat gain.

A Summary Review on Experimental Studies for PCM Building Applications: Towards Advanced Modular Prototype

The use of phase change material (PCM) as a thermal energy storage system integrated in new buildings, and as retrofits in old buildings, proved its merit as promising renewable energy source. Heating and cooling building applications of PCM have been studied by plenty of scientists, globally, on the basis of numerical and experimental analysis. The performed experiments have mainly focused on one application—active or passive—using permanent prototype design for a certain duration and weather condition. The current study is a new review that focuses on two complementary aspects: (1) Reviewing latest studies in PCM domain and assessing the thermal performance of implemented prototypes within the conducted PCM experimental studies, namely, the effect of the design on the number of acceptable variables and possible PCM applications; and (2) suggesting a new, advanced, flexible, and modular prototype designed to enable several applications of PCM to be adapted and combined within the model. It was implied that the new design allows different configurations that are lacking in the literature and serves for future PCM building applications of thermal analysis towards PCM integration optimization, as an attempt for transforming residential compartments into net zero energy buildings. The designed prototype overcomes the deficiencies found in previous reviewed experimental facilities.

Visible and near-infrared programmable multi-level diffractive lenses with phase change material Sb2S3.

In this paper, we discuss flat programmable multi-level diffractive lenses (PMDL) enabled by phase change materials working in the near-infrared and visible ranges. The high real part refractive index contrast (Δn ∼ 0.6) of Sb2S3 between amorphous and crystalline states, and extremely low losses in the near-infrared, enable the PMDL to effectively shift the lens focus when the phase of the material is altered between its crystalline and amorphous states. In the visible band, although losses can become significant as the wavelength is reduced, the lenses can still provide good performance as a result of their relatively small thickness (∼ 1.5λ to 3λ). The PMDL consists of Sb2S3 concentric rings with equal width and varying heights embedded in a glass substrate. The height of each concentric ring was optimized by a modified direct binary search algorithm. The proposed designs show the possibility of realizing programmable lenses at design wavelengths from the near-infrared (850 nm) up to the blue (450 nm) through engineering PMDLs with Sb2S3. Operation at these short wavelengths, to the best of our knowledge, has not been studied so far in reconfigurable lenses with phase-change materials. Therefore, our results open a wider range of applications for phase-change materials, and show the prospect of Sb2S3 for such applications. The proposed lenses are polarization insensitive and can have the potential to be applied in dual-functionality devices, optical imaging, and biomedical science.

Energy saving simulation of phase change materials in the enclosure structure of archives warehouse in Lhasa

The archives warehouse is an important place to save archives. In order to ensure the safety of archives, the requirements of temperature control are relatively strict in warehouse. Phase Change Material(PCM) is a kind of green environmental protection material, which has the characteristics of phase change latent heat, its energy-saving effect is closely related to outdoor climate conditions. The annual solar irradiance in Lhasa is high, which is conducive to the latent heat effect of PCM. The application of PCM to the enclosure structure of archives warehouse can play the role of thermal insulation in summer and winter. Adding PCM with phase change temperature of 8 °C outside the outer enclosure structure can slow down the temperature fluctuation of the inner wall of the warehouse by 1.66 °C and reduce the energy consumption of the warehouse by 26.05%, the energy-saving effect of archives warehouse is achieved.

Microencapsulation of high temperature metallic phase change materials with SiCN shell

Metallic phase change materials (PCMs) have the advantages of large phase change latent heat, high heat storage density and broad application prospects in various high temperature industrial waste heat recovery and utilization. However, due to the strong corrosion of molten metal at high temperature, appropriate packaging technology is the prerequisite for the promotion and application of metallic PCMs. In this research, a high temperature PCM microencapsulating technology with SiCN shell and a new microencapsulation method was proposed. The high temperature microencapsulated phase change materials (MEPCMs) with the core–shell mass ratios of 5:1, 4:1 and 3:1 were prepared by “solvent evaporation-heating curing” method, using SiCN cured by organic polysilazane (OPSZ) as heat resistant shell material and Al-Si particles as core PCMs. The mechanisms of shell formation and coating of OPSZ were studied experimentally, as well as the material properties and thermal performance of MEPCMs. With the increase of temperature, OPSZ gradually formed a dense SiCN shell on the surface of Al-Si particles. The experimental results showed that MEPCMs with the core–shell mass ratio of 4:1 had a high phase change temperature (571.9 °C-573.7 °C) and good heat storage capability (281.2 J/g-282.9 J/g). SiCN shell was conducive to maintain a complete core–shell structure, and exhibited excellent thermal resistance and oxidation resistance to protect inner core materials during thermal cycles. Therefore, the prepared microcapsule was a potential heat storage material, which provided a new idea for developing microencapsulation method of high temperature PCMs.

Dynamic coupled heat transfer and energy conservation performance of multilayer glazing window filled with phase change material in summer day

Windows as indispensable for buildings play an important role in decreasing building energy consumption and improving indoor thermal comfort. However, the conventional windows made of the pure glazing units fail to meet the requirements of energy conservation for buildings due to poor thermal insulation. Recent researches found that the application of phase change materials (PCM) can improve the heat transfer performance of glazing unit and the PCM-filled glazing units have advantage in reducing building energy consumption and improving indoor thermal comfort. Therefore, the dynamic coupled heat transfer and energy conservation performance of PCM-filled multilayer glazing unit are investigated numerically in this work. A transient coupled heat transfer model considering conduction, phase change and solar radiation transfer in glazing unit is established, and the energy conservation performance is analyzed based on the heat transfer calculation. Results show that the PCM-filled multilayer glazing unit can significantly reduce energy consumption compared with pure glazing unit, and the energy saving rates are 14.55% for double glazing unit, 33.89% for triple glazing unit and 50.71% for four glazing unit, respectively. In addition, the effects of optical and thermal parameters of PCM on thermal performance of glazing units are investigated thoroughly. It is found that the PCM-filled multilayer glazing unit has advantages in thermal insulation which is good choice for transparent envelope in the building fields.

Granular PCM-Enhanced Plaster for Historical Buildings: Experimental Tests and Numerical Studies

The construction sector is among the major players responsible for global energy consumption and therefore related emissions, both because of the constantly increasing indoor air quality standard which requires increasingly higher energy demands as well as the great share of historical buildings which are now obsolete and are not up to date with current regulations. Phase change materials (PCMs) applied on the building envelope represent a feasible possibility to improve the performance of existing buildings, also the historical ones, increasing their thermal inertia without violating any legal restriction or causing further alterations to the structure. More specifically, focus of this research was on the addition of a granular paraffin PCM into a lime-based plaster. Experimental tests at lab scale and numerical simulations with COMSOL Multiphysics were carried out to characterize the plasters realized, namely one reference lime-based plaster and one with incorporated 10% by mass of granular PCM (named REFp and PCMp, respectively). The behavior of these plasters applied on the exterior side of a wall was then simulated and compared in terms of temperatures and heat fluxes. However, considering that the estimated thermal conductivity of the reference lime-based plaster was lower than the values found in literature, the simulations were carried out considering an additional plaster, namely a lime-based plaster (renamed LITp), whose properties were found in literature and considered quite representative of a consistent share of existing historical buildings. Great improvements were observed from the application of PCM into the plaster, with reductions of the incoming energy between 9% and 18%.

WOOD/PCM composite with enhanced energy storage density and anisotropic thermal conductivity

Phase change materials (PCMs) have great potential in energy-saving and environmental field due to their high latent heat. The deficiencies that restrict the application of PCMs are their poor thermal conductivity and liquid leakage after phase change. To shoot these problems, a thermally-induced flexible WOOD/PCM composite with enhanced energy storage density and anisotropic thermal conductivity has been proposed. This composite consisted of polyethylene glycol 6000 (PEG6000), delignified balsa wood and boron nitride (BN). The results revealed that the melting enthalpy and freezing enthalpy of WOOD/PEG6000 composite were 209.3 ​J/g and 214.9 ​J/g, which had an augment of about 8% comparing with pure PEG6000. After adding 33 ​wt% BN to the composite, its thermal conductivity in the out-of-plane direction reached 0.96 ​W/(m·K), while the radial thermal conductivity was 0.36 ​W/(m·K). The controllable anisotropic thermal conductivity implies a good application in the environment where forced unidirectional heat dissipation is needed. Furthermore, the composite also shows excellent thermal induced flexibility, such as bending and compression, which is significant in reducing thermal contact resistance with substrates in application. This work indicates that the prepared PCM composite has a great potential application in thermal energy storage and thermal management.

Modeling and Validation of the Enthalpy-Temperature Curve for Phase Change Materials

Thermo-dynamical studies have proven that introducing phase change materials (PCM) to the building’s envelope could decrease the heat transfer exchange rate and maintain the inside thermal comfort for long periods. Among all types of PCM applications in the building’s envelope, the cement-plaster is the most cost-effective. The composite PCM-plaster material was formed by mixing predefined mass percentages of PCM microcapsules with local cement, sand, and water. This paper aims to establish a direct solution for the enthalpy-temperature variations for the PCM composite material. This solution will enable to study the effect of the composite material on buildings' energy loads. The obtained model has been also validated against experimentally tested samples and results were in complete agreement. This model will enable researchers to obtain the correct heat response when the envelope of the building is subjected to different external weather solicitations.

The Impact of Integrating Phase Change Material Upon Indoor Air Temperature in Hot Climates

The aim of this paper is to identify the effect of PCM as a building material of commercial building envelope on the indoor air temperature within a hot climatic context as Egypt. This paper will expose the potentials of using Phase Change Material (PCM) as an integral part of the building process to save energy, where it first introduces the current environmental challenges and identifies the impact of Thermal Energy Storage as a sustainable approach. Two different types of PCM will be tested in an experimental space in Egypt on different building model orientations and different PCM allocations, to test their effect on indoor air temperature. This will be practically examined by DesignBuilder simulation, to explore the possibilities of improving indoor thermal comfort within the studied types. Finally, conducting a set of recommendations for PCM application as a building material within the Egyptian context.

Development of capric acid-stearic acid-palmitic acid low-eutectic phase change material with expanded graphite for thermal energy storage

Excessive building energy consumption and shortage of fuel resources promote the vigorous development of phase change energy storage technology. The application of phase change materials (PCMs) in the construction industry can reduce indoor temperature fluctuation and the load of energy consuming equipment. To explore PCMs for thermal energy storage in the field of building energy conservation, ternary low eutectic is prepared by capric acid (CA), stearic acid (SA) and palmitic acid (PA). Take into consideration of the poor thermal conductivity and easy leakage in molten state of organic PCMs, with porous matrix of expanded graphite (EG) as the carrier, CA-SA-PA/EG with a mass ratio of CA-SA-PA to EG of 12:1 was prepared by vacuum adsorption method. It is measured by differential scanning calorimetry (DSC) that CA-SA-PA/EG has a melting temperature of 25.39 ℃ and a melting latent heat of 140.22 J/g, which are higher than that of CA-SA-PA, indicating the addition of EG slightly enhances the phase transition characteristics of CA-SA-PA. The identification of microstructure, chemical structure and crystal structure confirmed that CA-SA-PA was evenly adsorbed into the pores of EG, and they have good compatibility without chemical reaction. Besides, the thermal performance and reliability analysis also show that CA-SA-PA/EG has high thermal conductivity of 3.059W/m∙K, good heat storage and release performance and stable thermal and chemical properties, and is a potential candidate in the application field of latent heat storage.