Encapsulated Phase Change Materials Research Articles

A study on a milk chiller latent storage system with phase change material encapsulated spherical balls

For dispersed or remotely located families, the collection of raw milk takes place less frequently or transportation to the nearest center is not feasible. It requires chilling of collected milk from udder temperature (∼35 °C) to storage temperature (∼4 °C) and maintaining it throughout thus it demands running chilling at the discrete locations. In this study, a novel design of a milk chiller for coolness storage of 12/24 h based on phase change material is presented. System performance has been demonstrated following the prevailing practice of milk collection and loading/unloading of milk. By switching off the refrigeration after a certain interval, the coolness storage was demonstrated to meet the chilling conditions even during the non-availability of power. The study proposes an integrated portable mobile milk chilling system that can move between solar PV plants and the nearest electric grid during non-sunny days. The proposed milk chiller latent storage system (MC-LSS) contains three major components: a helical coil for refrigerant circulation during charging of the system, spherical capsules for encapsulating phase change materials and interspaced occupied brine solution for storing coolness and circulating throughout PCM-filled capsules. MC-LSS is tested under two cases: FLS-12(first loading of milk chiller and storage for 12 h) and SLS-12 (second loading of milk and storage for 12 h). The temperature history of the Milk chiller latent storage system for the FLS-12 h case is qualitatively analyzed which shows an appreciable reduction in milk temperature around 10–15 °C within the first 20 min and in another ∼40 min of further cooling, milk temperature attains the desired storage temperature (4–5 °C).

Encapsulated Phase Change Material Slurries as Working Fluid in Novel Photovoltaic Thermal Liquid Systems: A Comprehensive Review

Today, energy generation from renewable energy sources is of great interest. Photovoltaic (PV) systems, in this regard, have much to offer, but they suffer from low efficiency, which further deteriorates due to overheating under insolation. So, they need removal of heat from their bodies for better efficiency, which resulted in the introduction of PV-Thermal (PVT) systems, which feature heat transfer fluids (HTF) to draw the heat and deliver it to other systems that make use of it. Nevertheless, the best HTF has yet to be developed. Water-based fluids with additives or nanoparticles seemed like a good choice until HTFs that featured the use of encapsulated phase change materials (ePCM) were proposed. The findings of early studies and subsequent research revealed that the use of ePCM slurries (ePCM-Ss) as the working fluid in PVT systems increased the thermal efficiency, electrical efficiency, and overall efficiency without a notable increase in pumping power. However, preparation of ePCM-Ss is much more complex in many aspects compared to conventional HTFs, as it involves numerous parameters, including but not limited to the use of various shell and core materials, the variety of production methods, the homogeneity of the resulting capsules, the use of additives, the core to shell ratio, and the mass fraction of ePCM in the slurry. All these require an extensive and exhaustive study with quite a lot of background knowledge and interdisciplinary collaboration, as the proper selection of PCM materials and synthesis methods, as well as the correct concentration in the best CF, involve several aspects and expertise in a number of other fields. These parameters also significantly diversify and differentiate ePCM-S by affecting its suspension stability, rheological properties, and thermal properties. In recent years, PCMs have become an attractive research field for researchers due to their advantages. Although there are quite a number of studies addressing ePCM-S, none provide a holistic approach, and they just deal with a certain aspect of this broad topic. This study, therefore, aims to constitute a fundamental guide to refer to from the very beginning to the final implementation of the ePCM-Ss as the working fluid in PVT systems by addressing all steps, aspects, and almost all effective parameters in terms of advantages, disadvantages, challenges, and opportunities.

Entropy and hydrothermal analyses of nano-encapsulated phase change materials within a U-shaped enclosure: Impact of diverse structures of baffles and corrugated wall

The entropy and hydrothermal inspections of natural convection (NC) flow and heat transfer (HT) within cavities may absorb a raft of researchers' attention owing to their significant industrial applications in the electronic devices' cooling, solar collectors, heat exchangers, micro-electro-mechanical systems, etc. Based on this requirement of efficient and long-time cooling, internal baffles, encapsulation of phase change material (PCM) by nanoparticle (NEPCM), internal corrugated hot triangular wavy wall are considered in this examination to ameliorate HT into PCM, thereby HT increment speeds up the rate of PCM melting and reduces the operating period for PCM-based thermic management. The present study investigates the NC of magnetic NEPCMs within a U-shaped enclosure with the bottom as a triangular wavy corrugated wall (subject to stable heat flux due to sunlight transmitted from a PTSC's reflector) and comprised of two cold baffles of variable length. The FEM is the numerical approach to achieving the desired solution. The results are that growth of Hartmann number results in the reduction of streamlines, isotherms, and horizontal and vertical velocities. Ascent of baffle length (l) yields amelioration of the local HT rate while the height of corrugated wall exhibits a reverse effect with/without magnetic field impact.

Encapsulation of polyethylene glycol as a phase change material using alginate microbeads to prevent temperature fluctuation- Case study: Fish packaging

Encapsulated PCM (phase change materials) has been developed to provide a thermal buffering system for food packaging. In this study, polyethylene glycol 400 (PEG) as a PCM was encapsulated in alginate in concentrations of 30, 40 and 50% (W/V) using calcium chloride (CaCl 2 ) in concentrations of 0.5, 1, 1.5%. Crystallization temperature, melting temperature and melting enthalpy of PCM decreased after encapsulation. The optimum encapsulated PEG (50% of PEG and 0.5% CaCl 2 ) had a diameter of 2.21 ± 0.54 μm. FTIR analysis of encapsulated microcapsules indicated characteristic peaks of alginate and pure PEG. TGA analysis showed more thermal stability for encapsulated PCM than pure PCM. After 100 thermal cyclic test microencapsulated beads showed some decrease in melting enthalpy, while other features of encapsulated PCM were almost intact. Encapsulated PCM was used for fish packaging to determine its effectiveness in controlling temperature fluctuation. When the packages were removed from the freezer, fish samples with the package containing encapsulated PCM and control package reached to 0 °C after 6500s and 3000s, 5 °C after 9030s and 4040s, 10 °C after 11520s and 5053s, and 25 °C after 19000s and 8200s, respectively. The data showed that using encapsulated PEG in fish packaging had a positive effect on preserving pH, water holding capacity, total volatile basic nitrogen, and thiobarbituric acid value. The results demonstrated that alginate could effectively encapsulate PEG, and the produced encapsulated PCM can be used for increasing of shelf life of perishable food during temperature fluctuations. • Novel food packaging materials were developed using alginate based PCM microcapsules. • The efficiency to maintain the cold temperature in packaged fish increased. • The shelf-life of product emproved by application of encapsulated PEG in packages.

Biomimetic submicromotor with NIR light triggered motion and cargo release inspired by cuttlefish.

Biomimetic design is very helpful and significant for the smart construction of micro/nanomotors with artificial intelligence. In this work, inspired by cuttlefish, who can rapidly eject poisonous ink and are also capable of fast movement to escape, we designed and fabricated a biomimetic submicromotor with the ability of simultaneous quick movement and a temperature threshold caused explosive cargo release triggered by near infra-red (NIR) light irradiation, which was approximately equivalent to the action of cuttlefish when encountering a predator. The yolk@shell structured polydopamine@mesoporous silica (PDA@MS60) with immovable and asymmetric yolk distribution was employed as a platform, and this was followed by the simultaneous encapsulation of phase change materials (PCM) and cargo molecules. The NIR light irradiation could not only propel the direct motion of the submicromotor, but also caused the explosive release of the cargo loaded in the submicromotor when the temperature exceeded the melting point of the PCM.

Silicon-Containing Additives in Encapsulation of Phase Change Materials for Thermal Energy Storage

Microencapsulated phase change materials (MEPCMs) are effective solutions for addressing the issue of leakage that phase change materials (PCMs) face in thermal energy storage devices. Their applications are ubiquitous as PCMs are utilized in industries such as logistics, construction, electronics, etc., thus, an efficient method to prevent problems such as leakage and poor thermal conductivity is to encapsulate the PCM which not only renders it leakage-proof but also impart mechanical strength and enhanced thermal properties. The application of silicon-based additives is one of the most studied methods to impart such desired properties. We discuss the silicon-containing compounds which are commonly employed in core-shell matrix of encapsulated PCMs, namely, siloxanes and silicone, silicon nitride, silicon carbide, silica/SiO2, and other silicon-containing additives as they are able to provide synergistic improvements and exhibit enhanced physical properties. In this review, the different silicon compounds used as additives or main shell matrix are discussed, the general fabrication of the MEPCM and its thermophysical properties will be briefly highlighted. Lastly, we also examine its application and performance in thermal storage and thermal management. We hope to provide a broader perspective of silicon-containing MEPCM for those who are working in the similar field of research.

Modelling and optimisation of a battery thermal management system with nano encapsulated phase change material slurry for 18650 Li-ion batteries

Modelling and optimisation of a battery thermal management system with nano encapsulated phase change material slurry for 18650 Li-ion batteries

2D nanomaterial aerogels integrated with phase change materials: a comprehensive review

This review showcases how 2D nanomaterial-based aerogels can be integrated with PCMs, marking a milestone in interdisciplinary research. It covers the latest breakthroughs in aerogel fabrication and their potential applications in composite PCMs.

A green, robust, and versatile BN nanosheet unidirectional aerogel encapsulated phase change material for effective thermal management of electronics and solar-thermoelectric conversion

A novel BN nanosheet unidirectional aerogel encapsulated phase change material for effective thermal management of electronics and solar-thermoelectric conversion.

Performance Assessment of Three Latent Heat Storage Designs for a Solar Hot Water Tank

Solar hot water tanks (SHWT) based on a latent heat storage system are gaining momentum for their integration into solar heater water collectors. They can efficiently store daytime solar thermal energy and shift on-peak period loads to off-peak periods. However, their performance is generally limited by the tank configuration, the design of the thermal storage system, and the selection of the appropriate phase change material (PCM). This work presents a numerical investigation of three SHWT-PCM storage designs. A mathematical model was developed to predict the effectiveness of the geometric design and operating conditions in the SHWT-PCM system. Moreover, a sensitivity analysis was performed on the PCM type and PCM thermo-physical properties. The obtained numerical results demonstrated that the energy efficiency of the SHWT-PCM system was significantly impacted by the PCM thermo-physical properties (melting temperature, thermal conductivity, and enthalpy). In addition, it was found that using encapsulated PCM tubes with an external PCM jacket in the SHWT can result in a thermal efficiency of 70%.

Fatty acid eutectics embedded in guar gum/graphene oxide/boron nitride carbon aerogels for highly efficient thermal energy storage and improved photothermal conversion efficiency

Carbon aerogels with low density, high compressibility and fatigue resistance, are of great interest for the encapsulation of phase change materials (PCMs) to resolve their leakage and low thermal conductivity issues, thus providing exciting potential for thermal management and energy storage. In this work, we successfully fabricated interconnected carbon aerogels with superior mechanical performance from graphene oxide (GO), thermally conductive hexagonal boron nitride (BN), and green biomass guar gum (GG). The GG with long soft molecular chains stabilized the porous structures of the carbon aerogels through hydrogen bonding. GG also maintained the even dispersion of BN in the carbon skeleton, forming a connected thermal conductive network. Furthermore, the stearic acid (SA)-capric acid (CA) binary eutectic PCMs were successfully capsulated in the porous structures of the obtained GG/GO/BN carbon aerogels to fabricate composite PCMs with high thermal conductivity and good shape stability, which overcoming the limitations of single PCMs and expanding their thermal energy storage applications. The composite PCMs exhibited an excellent energy storage capacity of 161.63 J/g with almost no change after 100 thermal cycles. In addition, the thermal conductivity of the composite PCMs increased to 0.6061 W∙m−1∙K−1, which was nearly three times that of SA-CA, and the photothermal conversion efficiency of the composite PCMs reached 92.56 %.

Finite element method (FEM) analyses of the entropy and convective process within an inclined porous T‐shaped domain using nano‐encapsulated phase change materials (NEPCMs)

AbstractNumerical treatments based on the finite element method (FEM) are carried out for the entropy generation and convective process within inclined T‐shaped enclosures using the nano–encapsulated phase change materials (NEPCMs). The domain is filled by glass balls as a porous medium and the Brinkman‐extended non‐Darcy model is applied. For the worked mixture, the overall heat capacity of the encapsulated nanoparticles is estimated using the heat capacity of the core and shell and sine profiles are introduced for the latent heat of the change phase. Three different designs are performed for the considered geometry based on the aspect ratio of the boundaries. During the simulations, various values of the fusion temperature , the inclination angle γ and different designs of the considered domain are taken into account and the Ryleigh‐Darcy number is varied between 102 and 104. The main outcomes disclosed that, for the fixed values of and γ (, the increase in the fusion temperature causes a shifting of the melting‐solidification zones from the top boundary to the bottom of the horizontal channel.

MHD Nanofluid Convection and Phase Change Dynamics in a Multi-Port Vented Cavity Equipped with a Sinusoidal PCM-Packed Bed System

In this study, impacts of using a sinusoidal shape encapsulated phase change material (PCM) packed bed (PB) system on the phase change and thermal performance are analyzed in multi-port vented cavity under a partially active magnetic field during hybrid nanoliquid convection. The current study is performed for different magnetic field strengths of domains (Hartmann number between 0 and 50), wave number (between 1 and 8), wave amplitude (between 0.01 H and 0.15 H), and nanoparticle loading (between 0 and 2%) by using the finite element method. The sinusoidal shape of the PCM-PB zone and varying its geometrical form are both found to affect the phase change process and thermal performance. When wave amplitude (Hp) rises from 0.01 H to 0.15 H, full phase change time (t-fr) increases by about 33% while average Nu increases by about 55%. When a partially active magnetic field is imposed at the highest value, up to 30.3% reduction in t-fr is obtained, while average Nu rises by about 9% at t = 18 min. The value of t-fr is reduced by about 15% while spatial average Nu rises by about 55% at the highest nanoparticle loading.

A natural convection conjugate heat transfer of Nano-Encapsulated Phase Change Materials (NEPCMs) in an inclined blocked square enclosure

The current investigation deals numerically with a two-dimensional steady laminar flow natural convection heat transfer of a dilute suspension of a base fluid and suspension of Nano Encapsulated Phase Change Materials (NEPCMs) nanoparticles saturated inside an inclined square enclosure with a centered internal conducting square block with a ratio of 0.5. The enclosure inclination angle varies from 0° to 90° with increments of 15°, and block thermal conductivity to the host fluid has been chosen to be 0.2 and 5. The obtained results are in excellent agreement with those available in the literature for validation. The findings reveal that the heat transfer depends considerably on the inclination angle, block thermal conductivity ratio, and Stefan number for all considered ranges. The present results suggest that the average Nusselt number rate is notably enhanced as the inclination angle rises from 0° to 90° for thermal conductivity KR = 0.2 and KR = 5; this enhancement is more evident as the Rayleigh number is increased. The average Nusselt number improves by 5%, 153%, 558%, and 1120% for Rayleigh numbers of 103, 104, 105, and 106, respectively, when the inclination angle varies from 0° to 90° for a thermal conductivity ratio of 0.2. This improvement is somewhat reduced in the case of a thermal conductivity of 5, where the average Nusselt number grows by around 0.4%, 27%, 213%, and 537% for Rayleigh numbers 103, 104, 105, and 106, respectively. The higher value of the latent heat capacity of encapsulated particles enhances the heat transfer rate; the decreased Stefan number induces a notable improvement in the average Nusselt number. This enhancement is more evident as the inclination angle increases. The findings clearly show a considerable influence on the isotherms and heat capacity ratio distributions for all considered block thermal conductivities and Rayleigh numbers.

Cyclic performance characterization of a high-temperature thermal energy storage system packed with rock/slag pebbles granules combined with encapsulated phase change materials

A thermocline hybrid sensible-latent heat storage system is one of the promising solutions to avoid the challenges encountered by the two storage techniques to what extent and holds the benefits of both methods. Hence, the present study investigates the cyclic performance characteristics of a thermal energy storage system packed with rock/slag pebbles granules combined with encapsulated phase change material (PCM). A concentric-dispersion model is developed to evaluate cyclic behavior based on two different volume fractions. Two different scenarios are adopted for each volume fraction. A hypothetical scenario evaluates the behavior assuming that two PCMs at both tank extremes have the same thermo-physical properties of solid granules in the mid-layer. The average scenario evaluates behavior using the average thermo-physical properties of the three storage materials packed in a tank. The results show that the two adopted strategies greatly influence the system’s performance indicators. Based on the hypothetical strategy, the total bed energy stored in cases 2 and 4 is greater than that of the average scenario, resulting in charging 53.8 kWh in case 2 and 54 kWh in case 4. Besides, the system’s energy recovered has a peak value of 43.3 kWh in a hypothetical strategy in cases 4 and 1, whereas case 3 has the lowest value of 36.3 kWh in the average scenario. The increased percentages in the capacity ratio of the average scenario than a hypothetical scenario are 5.5 %, 9.84 %, 3.52 %, and 9 % in cases 1, 2, 3, and 4. Moreover, they reach 9.8 %, 16.45 %, 10 %, and 17.55 % in the same cases for the total utilization ratio.

Development of BaSO4@n-eicosane phase-change microcapsules with high corrosion resistance for thermal regulation application in architectural coatings

Microencapsulated phase change materials (PCMs) are a promising candidate to provide huge opportunities for energy-saving buildings; however, the most usually used shell materials for encapsulation of PCMs, such as CaCO3 and SiO2, have poor corrosion resistance, resulting in a limitation in their practical applications in the architectural field. Focusing on an effective solution to this issue, we have developed a new type of microencapsulated PCM with n-eicosane as a core and BaSO4 as an inorganic shell through emulsion-templated controllable precipitation. The resultant BaSO4@n-eicosane microcapsules exhibit an ellipsoidal morphology and a well-defined core-shell microstructure, together with a satisfactory latent heat capacity of over 100 J/g. The BaSO4 shell contributes high thermal conduction, rapid heat transfer, high acid and alkali resistance, and outstanding thermal cycling stability to the fabricated microcapsules. This can meet the requirement of long-term use in thermal self-regulatory architectural coatings. The developed composite coatings containing the BaSO4@n-eicosane microcapsules exhibit efficient temperature regulation performance along with high hardness, good scratch resistance, and high corrosion resistance. Based on an investigation into the practical application of the composite coatings, the developed composite coatings can be used for the house roof coating to reduce the indoor temperature effectively, indicating good application potential for comfort temperature regulation in energy-saving buildings. This study offers a new approach to develop multifunctional architectural coatings for sustainability.

Testing the encapsulation of phase change materials using supercritical emulsion extraction

Continuous supercritical CO2 emulsion extraction (SEE-C) technology is proposed for the first time to test the encapsulation of two fatty acids: Stearic acid and isopropyl myristate, to be used as model Phase Change Materials (PCM) in a PMMA shell. Spherical microcapsules with smooth surface and a mean diameter between 163-431 nm have been produced. Encapsulation efficiencies larger than those in the literature and up to a max of 91 % were measured. Therefore, supercritical PCM encapsulation can open new perspectives in thermal energy storage application.

Free convection from a localized heated cylinder with nano encapsulated phase change material and water in a square enclosure

The present study looks on free convection caused by a temperature variation between a cold enclosure and a hot cylinder. The upper cylinder surface has a localized heated, which is otherwise adiabatic. The enclosure’s empty area is filled with hybrid nanofluids. This new type of fluid consists of nano-encapsulated phase-change material (NEPCM) suspended in the water (H2O) as the host fluid. The NEPCM has a polyurethane as a shell with an n-nonadecane as a core within. The n-nonadecane stores heat on charging state and releases the heat on discharging state. During charging and discharging, the latent heat was extracted and it can circulate the heat inside the enclosure. The governing parameters considered are the heater portion, 0.25≤S≤0.75, the Stefan number, 0.2≤Ste≤0.7, the fusion temperature, 0.1≤Θf≤0.5, the heating intensity, 104≤Ra≤106, and the NEPCM concentration, 0≤ϕ≤0.05. The findings demonstrate that by suspending 1% of hybrid particles, the heat transfer rate may be increased over 10%.

Numeric study of geothermal borehole heat exchanger enhancement via phase change material macro encapsulation

This article addresses the theoretical effect of using geothermal boreholes enhanced with macro-encapsulated phase change materials (PCM) employed with a ground sourced heat pump (GSHP). The aim being the improvement of the heat pump performance through soil temperature stabilisation, taking advantage from the PCM inherent property of changing phase at a constant temperature, that can be matched with the temperature of the surrounding soil, contributing as well to increase the energy storage capacity underground. The numeric work studied different PCM thermal parameters with regards to their influence on the overall behaviour of the heat pump, with different operation modes (On/Off and Inverter) changing the solidus and liquidus temperatures and phase change enthalpy values. The CFD results showed that, while it underperformed having 0.15% difference in the best of cases (specifically the On/Off mode), it used in the best case scenario only 30% of the stored energy in the PCM. The application of macro-encapsulation did provide a stabilising effect to the soil and heap pump operation as it was originally intended to do, helping reduce energy expenditure by the system. Significant modifications are needed in order to improve, both concerning geometry and encapsulation techniques to overcome the PCM and other materials thermal limitations. • Combination of vertical ground sourced heat pump boreholes with macro encapsulated PCM for energy storage, with minimal modifications of a double “U” array. • Parametric analysis of PCM thermophysical properties influence on borehole heat exchangers behavior comparison. • 3D Computational Fluid Dynamics simulations, for full turbulent conditions of the heat transport fluid flow, were developed in combination to a scheduled work timeframe to evaluate the heat transfer process. • The results demonstrate that the proof of concept showed that improving the storage of the Phase Change Materials enables a better borehole thermal performance and storage capacity, decreasing borehole depth and decreasing installation costs.

Novel 3D thermal energy storage materials based on highly porous patterned printed clay supports infiltrated with molten nitrate salts

One of the main drawbacks of phase change materials (PCM) to be employed as thermal energy storage (TES) systems in energy applications, such as concentrated solar power (CSP), is the liquid leakage, which considerably reduces the storage efficiency. To overcome this issue, a novel approach is presented, which is based on the development of three-dimensional (3D) engineered TES structures (3DTES) formed by highly porous patterned 3D printed low-cost clay supports (up to ~85% of total porosity) that are infiltrated with a molten sodium nitrate salt. Expanded vermiculite supports are additive manufactured by robocasting, a direct ink writing technology, using clay aqueous inks with a pseudoplastic behavior. 3DTES are lightweight (~1.8 g·cm −3 ), easy to handle, mechanically robust (~68 MPa) and exhibit high PCM encapsulation capacity (~78%), avoiding the molten salt leakage. Furthermore, they present an enthalpy of fusion of ~136 J·g −1 , excellent thermal stability, and high thermal energy storage efficiency (~80%) and thermal conductivity (1.27 W·m −1 ·K −1 ), which is indicative of a great charging-discharging ability. The results open new opportunities through the 3DTES approach to manufacture promising affordable materials with outstanding performance for CSP applications. • Novel 3D engineered thermal energy storage structures (3DTES) are manufactured. • Highly porous 3D printed patterned clay supports are infiltrated with a molten salt. • 3DTES are light, easy to handle, robust and avoid the molten salt leakage. • 3DTES exhibit excellent efficiency, thermal stability and high thermal conductivity. • 3DTES are promising affordable materials with outstanding performance for CSP.