•Heat transfer enhancement techniques in PCM thermal storage systems are presented.•Combination of techniques for better performance was studied.•Studies include description, investigated parameters, ...key results, and conclusions.•Recommendations for current systems design and future research are provided.
The potential of phase-change materials (PCMs) for application in the fields of thermal energy storage and thermal management is well recognized, due to their remarkable energy storage density and negligible temperature variation during operation. However, these materials do face the primary challenge of low thermal conductivity which necessitates incorporation of heat transfer enhancement techniques. Heat transfer enhancement in these systems has been a subject of interest for numerous studies, many of which have focused on employing only one enhancement technique. Very few studies have investigated the combination of two or more techniques. This combination of techniques is referred to as hybrid heat transfer enhancement. This paper provides a review of the major studies on the hybrid heat transfer enhancement techniques. It was found from the study that best enhancement is achieved via the hybrid application of the heat pipe with fins or metal foam. It was also found that the hybrid use of nanoparticles with fins or metal foam is more efficient than the use of nanoparticles alone within the same containment volume. Further research is recommended to explore other possible hybrid enhancement techniques which could lead to improved performance of PCM-based systems.
Infrared stealth technology plays a vital role in development of defense industry and new military equipment. The current study focused on a novel type of flexible and foldable composite films based ...on polyimide (PI)/phosphorene (PR) hybrid aerogel and phase change material (PCM) for infrared stealth and thermal camouflage applications. The composite films were successfully obtained by fabricating a PI/PR hybrid aerogel through prepolymerizaton, film casting, freeze-drying, and thermal imidization, followed by vacuum impregnation of polyethylene glycol (PEG) as a PCM into the aerogel framework. The combination of PI and PR nanoflakes endows the hybrid aerogel with an effective enhancement in mechanical properties, near infrared absorption, and infrared photothermal conversion. The resultant composite films not only present prominent tensile and fatigue-resistant performance but also exhibit a good thermal regulation capability with a high latent-heat capacity of over 150 J/g. More importantly, the composite films demonstrate good infrared stealth and thermal camouflage performance on the high-temperature targets through effective thermal buffer and insulation. With ultralight, flexible, foldable, shape-tunable, and thermal self-regulatory characteristics, the PI/PR aerogel/PEG composite films developed by this work exhibit great application potential in infrared stealth and thermal camouflage for new military equipment.
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•A flexible and foldable composite film was designed for infrared stealth and thermal camouflage.•The film was based on the polyimide/phosphorene hybrid aerogel and phase change material.•The introduction of phosphorene enhances infrared absorption and photothermal conservation.•The film exhibit a good thermal regulation ability to buffer thermal swings.•The film shows great potential for stealth and camouflage applications in new military equipment.
•A novel battery thermal management system based on phase change material (PCM) and liquid cooling.•The PCM acts as a heat buffer to avoid the thermal runaway propagation.•Verifying the heat transfer ...model and thermal runaway model.•Avoiding the thermal runaway by optimizing some parameters of the proposed system.
In order to maintain the proper operating temperature and avoid thermal runaway propagation of lithium-ion power battery module, this paper proposes a novel hybrid battery thermal management system based on phase change material (PCM) and liquid cooling. In the proposed system, the operating temperature of the battery is maintained mainly by latent heat of PCM. In the case of thermal runaway condition, PCM acts as a heat buffer, and the heat dissipates through the liquid cooling system to avoid the thermal runaway propagation. The heat transfer model and the thermal runaway model are established and then verified. The performance of system is numerically analyzed under extreme operating and thermal abuse conditions. The results show that the proposed system combines the advantages of PCM and liquid thermal management schemes, which can fully meet the heat dissipation demand under extreme operating conditions. The high thermal conductivity of PCM is beneficial to the reduction of battery temperature but may cause thermal runaway propagation. The proposed system also have good heat dissipation capacity in avoiding the thermal runaway by optimizing some parameters, such as thethermal conductivity of PCM and water velocity.
•This article contains the experimental investigations of different cooling methods used for photovoltaic (PV) panels.•Phase change material (PCM), thermoelectric (TE) and aluminum fins were chosen ...as the cooling methods.•PV with fin system produced the highest power generation of 47.88 W while PV with PCM and TEM produced the lowest is 44.26 W.
This article contains the experimental investigations of different cooling methods used for photovoltaic (PV) panels. Phase change material (PCM), thermoelectric (TE) and aluminum fins were chosen as the cooling methods. The CaCl2·6H2O is chosen as one of the PCM which is widely used in the cooling of PVs and the other is the PCM with melting temperature above the surface temperature of the PV panel. By using TE material in different numbers (6, 8 and 12) and aluminum fins in different layouts, surface temperatures and output powers of PV panels were compared. It is observed that the PCM which is not chosen appropriately has insulation feature in the PV panel and enhances the temperature of the panel and decreases the output power. When the most successful cooling methods were tested under the same environmental conditions, PV with fin system produced the highest power generation of 47.88 W while PV with PCM and TEM produced the lowest power generation of 44.26 W.
The coupling between photonic spin and orbital angular momenta is significantly enhanced at the subwavelength scale and has found a plethora of applications in nanophotonics. However, it is still a ...great challenge to make such kind of coupling tunable with multiple sates. Here, a versatile metasurface platform based on polyatomic phase‐change resonators is provided to realize multiple‐state switching of photonic angular momentum coupling. As a proof of concept, three coupling modes, namely, symmetric coupling, asymmetric coupling, and no coupling, are experimentally demonstrated at three different crystallization levels of structured Ge2Sb2Te5 alloy. In practical applications, coded information can be encrypted in asymmetric mode using the spin degree of freedom, while revealing misleading one without proper phase change or after excessive crystallinity. With these findings, this study may open an exciting direction for subwavelength electromagnetics with unprecedented compactness, allowing to envision applications in active nanophotonics and information security engineering.
Multistate switching of photonic angular momentum coupling, namely, symmetric, asymmetric, and no coupling, is experimentally demonstrated at different crystallization levels of structured GST. In practical applications, coded information can be encrypted in asymmetric mode using the spin degree of freedom, while revealing misleading one without proper phase change or after excessive crystallinity.
•A novel aluminum nitride-enhanced composite phase change material is proposed.•Aluminum nitride enhance thermal conductivity and stability of composite materials.•Aluminum nitride increase volume ...resistivity and mechanical strength of materials.•Composite phase change material display excellent battery thermal management effect.
Thermal management plays an important role in battery modules, especially under extreme operating conditions. Phase change materials (PCMs)-based cooling has been recognized as a promising approach that can prolong the life span of batteries and endure the passive thermal accumulation in the module. In this study, various mass fractions (0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) of aluminum nitride (AlN) were added to composite PCMs to serve as heat-transfer promoters. The effect of the AlN additives on the thermal conductivity, mechanical properties, and volume resistivity were analyzed, and the root causes originating from the morphologies and structures of the composite PCMs were further examined. The results indicated that adding 20 wt% of the AlN in the composite PCMs was an optimal strategy. In addition, an AlN/paraffin (PA)/expanded graphite (EG)/epoxy resin composite PCMs-based 18650 LiFePO4 battery module was designed for thermal management. This battery module exhibited much better heat dissipation and temperature uniformity than an air-cooled battery module, leading to a 19.4% decrease of the maximum temperature and a less than 1 °C temperature difference at a high discharge rate of 3C. Thus, it could be concluded that the AlN-enhanced composite PCMs thermal management system exhibited a prominent controlling temperature and balancing temperature capacity for the battery module.
Thermal energy storage technologies based on phase‐change materials (PCMs) have received tremendous attention in recent years. These materials are capable of reversibly storing large amounts of ...thermal energy during the isothermal phase transition and offer enormous potential in the development of state‐of‐the‐art renewable energy infrastructure. Thermal conductivity plays a vital role in regulating the thermal charging and discharging rate of PCMs and improving the heat‐utilization efficiency. The strategies for tuning the thermal conductivity of PCMs and their potential energy applications, such as thermal energy harvesting and storage, thermal management of batteries, thermal diodes, and other forms of energy utilization, are summarized systematically. Furthermore, a research perspective is given to highlight emerging research directions of engineering advanced functional PCMs for energy applications.
A comprehensive review regarding the tuning of the thermal conductivity of phase change composites for thermal energy conversion, storage, and utilization is provided, which gives an insightful understanding of the thermal energy storage and conversion processes. The aim is to stimulate potential emerging applications of phase change materials.
•Battery cooling system is modified with phase change material.•Novel cell-to-cell air cooling provides temperature rise less than 5 °C.•Cell-wise phase material cooling maintains temperature ...uniformity within 0.12 °C.•Modular arrangement simplifies capacity build-up and replacement of faulty cell.•Conjugate active and passive cooling reduces the maximum temperature in module.
In a conventional system, the cells of the entire battery pack are sandwiched in a single phase change material (PCM). The PCM material confining the corner cells may reject heat at a faster rate to the adjoining ambient air as compared to the cells located in the middle of the pack. In this work, the conventional battery layout system is modified to induce active and passive cooling for each cell of a battery module. For this, battery pack is arranged into several modules; each module comprised of six cylindrical cells in a 1S6P arrangement. Each cell is placed in a 4 mm cylindrical gap enclosure filled with phase change material and interconnected together for further cooling at inter-spacings. Cooling performance of such modified layout is reported at different discharge rates (2C and 4C) and ambient condition (27 °C, 35 °C and 40 °C). It is found that confined phase change material around each cell help in better heat dissipation from PCM and improved temperature uniformity in the module.
•Optimisation of PCM based cooling coupled with liquid cooling system.•System weight and consumption of different configurations is evaluated.•Suggesting a 2-sided cold plates hybrid system for BTMS ...of pouch cells.•Suggested hybrid BTMS can withstand cell-to-cell variation of battery cells.
In this paper, a novel design for hybrid battery thermal management systems (BTMS) is proposed and evaluated from the economic and engineering perspectives. Numerical models are compared with phase change materials (PCM) BTMS. Further, the suggested hybrid cooling system’s thermal performance at the pack level is investigated considering cell-to-cell variation. A three-dimensional thermal model is used for the numerical simulation of the battery cooling system. The probability distributions is utilised for the cell-to-cell variations of a 168-cell battery pack. Results shows that for a 53 Ah lithium-ion battery (LIB) under a 5C discharge rate, a hybrid cooling system with two-sided cold plates can reduce the maximum temperature from ∼64 ∘C to 46.3 ∘C with acceptable system weight and power consumption, which is used for further pack level simulation. It is concluded that the two-sided cold plate hybrid design system can manage the maximum average temperature as well as temperature difference of cells in the desirable range at extreme cases.
•The performance of a photovoltaic-thermoelectric hybrid system is investigated.•An integrated phase change material/cobalt oxide nanofluid heat sink is proposed.•Around 14% higher electrical power ...is experimentally achieved by this heat sink.•The exergy efficiency of the unit is improved by 17.8% at noon.
Nowadays, photovoltaic panels have been known as effective devices to harness solar energy. These panels mainly convert the UV and visible areas of the solar spectrum into electricity and the rest of the energy is dissipated. One of the favorable methods to take advantage of such dissipated heat is to combine thermoelectric generators (TEG) utilizing the IR area of the solar radiation with photovoltaic panels. Having the different and opposite impact on the efficiency of thermal photovoltaic cells (PV/T) and thermoelectric generators (TEG), the system operating temperature appears as a critical parameter in the productivity of a PV/T-TEG hybrid unit. In the present study, a novel heat sink for a PV/T-TEG hybrid system is introduced. The effectiveness of simultaneous usage of the Co3O4/water nanofluid and the improved phase change material (paraffin wax/Alumina powder) as a cooling method on the performance of the PV/T-TEG is examined throughout an experimental study. Then, the overall electrical, thermal and exergy efficiency of such a system is compared to the units with divers working fluids including water and 0.25%, 0.5%, and 1% nanofluid and the unit consisting of 1% nanofluid with non-enhanced PCM cooling method. The results reveal that using 1% nanofluid with enhanced PCM, as a cooling method, would improve the overall electrical efficiency by 12.28% compared to water cooling technique. Also, an increase of 11.6% in the exergy efficiency of the PV/T-TEG is observed in comparison with PV/T-TEG with the water cooling method. Hence, it could be concluded that the combination of this unit could contribute to harnessing solar energy more efficiently, compared to solo photovoltaic panels.
