scholarly journals A Review of Thermal Property Enhancements of Low-Temperature Nano-Enhanced Phase Change Materials

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2578
Author(s):  
Joseph D. Williams ◽  
G. P. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Low Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Phase Change Materials ◽  
Relative Effectiveness ◽  
Food Storage ◽  
The Stability

Phase change materials (PCMs) are of increasing interest due to their ability to absorb and store large amounts of thermal energy, with minimal temperature variations. In the phase-change process, these large amounts of thermal energy can be stored with a minimal change in temperature during both the solid/liquid and liquid/vapor phase transitions. As a result, these PCMs are experiencing increased use in applications such as solar energy heating or storage, building insulation, electronic cooling, food storage, and waste heat recovery. Low temperature, nano-enhanced phase change materials (NEPCM) are of particular interest, due to the recent increase in applications related to the shipment of cellular based materials and vaccines, both of which require precise temperature control for sustained periods of time. Information such as PCM and nanoparticle type, the effective goals, and manipulation of PCM thermal properties are assembled from the literature, evaluated, and discussed in detail, to provide an overview of NEPCMs and provide guidance for additional study. Current studies of NEPCMs are limited in scope, with the primary focus of a majority of recent investigations directed at increasing the thermal conductivity and reducing the charging and discharging times. Only a limited number of investigations have examined the issues related to increasing the latent heat to improve the thermal capacity or enhancing the stability to prevent sedimentation of the nanoparticles. In addition, this review examines several other important thermophysical parameters, including the thermal conductivity, phase transition temperature, rheological affects, and the chemical stability of NEPCMs. This is accomplished largely through comparing of the thermophysical properties of the base PCMs and their nano-enhanced counter parts and then evaluating the relative effectiveness of the various types of NEPCMs. Although there are exceptions, for a majority of conventional heat transfer fluids the thermal conductivity of the base PCM generally increases, and the latent heat decreases as the mass fraction of the nanoparticles increases, whereas trends in phase change temperature are often dependent upon the properties of the individual components. A number of recommendations for further study are made, including a better understanding of the stability of NEPCMs such that sedimentation is limited and thus capable of withstanding long-term thermal cycles without significant degradation of thermal properties, along with the identification of those factors that have the greatest overall impact and which PCM combinations might result in the most significant increases in latent heat.

Latent Heat Storage: Container Geometry, Enhancement Techniques, and Applications—A Review

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
S. Arunachalam
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Heat Exchangers ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Low Thermal Conductivity

Energy storage helps in waste management, environmental protection, saving of fossil fuels, cost effectiveness, and sustainable growth. Phase change material (PCM) is a substance which undergoes simultaneous melting and solidification at certain temperature and pressure and can thereby absorb and release thermal energy. Phase change materials are also called thermal batteries which have the ability to store large amount of heat at fixed temperature. Effective integration of the latent heat thermal energy storage system with solar thermal collectors depends on heat storage materials and heat exchangers. The practical limitation of the latent heat thermal energy system for successful implementation in various applications is mainly from its low thermal conductivity. Low thermal conductivity leads to low heat transfer coefficient, and thereby, the phase change process is prolonged which signifies the requirement of heat transfer enhancement techniques. Typically, for salt hydrates and organic PCMs, the thermal conductivity range varies between 0.4–0.7 W/m K and 0.15–0.3 W/m K which increases the thermal resistance within phase change materials during operation, seriously affecting efficiency and thermal response. This paper reviews the different geometry of commercial heat exchangers that can be used to address the problem of low thermal conductivity, like use of fins, additives with high thermal conductivity materials like metal strips, microencapsulated PCM, composite PCM, porous metals, porous metal foam matrix, carbon nanofibers and nanotubes, etc. Finally, different solar thermal applications and potential PCMs for low-temperature thermal energy storage were also discussed.

Thermal Characterization of High Temperature Inorganic Phase Change Materials for Thermal Energy Storage Applications

2012 ◽  
Author(s):  
Jamie Trahan ◽  
Sarada Kuravi ◽  
D. Yogi Goswami ◽  
Muhammad Rahman ◽  
Elias Stefanakos
Keyword(s):  
Thermal Properties ◽  
High Temperature ◽  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Melting Behavior ◽  
Scanning Calorimetry

As the importance of latent heat thermal energy storage increases for utility scale concentrating solar power (CSP) plants, there lies a need to characterize the thermal properties and melting behavior of phase change materials (PCMs) that are low in cost and high in energy density. In this paper, the results of an investigation of the melting temperature and latent heat of two binary high temperature salt eutectics are presented. Melting point and latent heat are analyzed for a chloride eutectic and carbonate eutectic using simultaneous Differential Scanning Calorimetry (DSC) and Thermogravimetric Analsysis (TGA). High purity materials were used and the handling procedure was carefully controlled to accommodate the hygroscopic nature of the chloride eutectic. The DSC analysis gives the values of thermal properties of the eutectics, which are compared with the calculated (expected/published) values. The thermal stability of the eutectics is also examined by repeated thermal cycling in a DSC and is reported in the paper along with a cost analysis of the salt materials.

scholarly journals Thermal Conductivity Enhancement of Phase Change Materials for Low-Temperature Thermal Energy Storage Applications

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 75 ◽  
Author(s):  
Randeep Singh ◽  
Sadegh Sadeghi ◽  
Bahman Shabani
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Low Temperature ◽  
Phase Change ◽  
Thermal Energy ◽  
Heat Load ◽  
Phase Change Materials ◽  
Solidification Processes ◽  
Energy Storage Applications ◽  
Melting And Solidification

Low thermal conductivity is the main drawback of phase change materials (PCMs) that is yet to be fully addressed. This paper studies several efficient, cost-effective, and easy-to-use experimental techniques to enhance thermal conductivity of an organic phase change material used for low-temperature thermal energy storage applications. In such applications, the challenges associated with low thermal conductivity of such organic PCMs are even more pronounced. In this investigation, polyethylene glycol (PEG-1000) is used as PCM. To improve the thermal conductivity of the selected PCM, three techniques including addition of carbon powder, and application of aluminum and graphite fins, are utilized. For measurement of thermal conductivity, two experimental methods—including flat and cylindrical configurations—are devised and increments in thermal conductivity are calculated. Melting and solidification processes are analyzed to evaluate melting and solidification zones, and temperature ranges for melting and solidification processes respectively. Furthermore, latent heat of melting is computed under constant values of heat load. Ultimately, specific heat of the PCM in solid state is measured by calorimetry method considering water and methanol as calorimeter fluids. Based on the results, the fin stack can enhance the effective thermal conductivity by more than 40 times with aluminum fins and 33 times with carbon fins. For pure PCM sample, Initiation of melting takes place around 37 °C and continues to above 40 °C depending on input heat load; and solidification temperature range was found to be 33.6–34.9 °C. The investigation will provide a twofold pathway, one to enhance thermal conductivity of PCMs, and secondly ‘relatively easy to set-up’ methods to measure properties of pure and enhanced PCMs.

Metallic Composites Phase-Change Materials for High-Temperature Thermal Energy Storage

2013 ◽  
Author(s):  
Xiaobo Li ◽  
Hengzhi Wang ◽  
Hui Wang ◽  
Sohae Kim ◽  
Keivan Esfarjani ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Phase Change Materials ◽  
Metallic Alloys ◽  
Heat Of Fusion ◽  
Latent Heat Of Fusion ◽  
High Latent Heat

Inorganic materials and organic salts are usually used as phase change materials (PCMs) for thermal energy storage. Some of these materials have high latent heat of fusion; however one major drawback of these materials is the low thermal conductivity, which limits the rate of charging and discharging process. In this paper, we studied metallic alloys (eutectic alloys or alloys with a narrow melting temperature range) as phase-change materials, which have both high thermal conductivity and high latent heat of fusion. A formula was presented from entropy change to predict the latent heat of fusion of metallic alloys. We found that the latent heat of fusion of alloys can be expressed from three different contributions: the latent heat from each element, the sensible heat, and the mixing entropy. From the theory we also showed that latent heat of fusion could be greatly increased by maximizing the entropy of mixing, which can be realized by introduce more elements in the alloys, i.e., form ternary alloys by adding elements to binary alloys. This idea is demonstrated by the synthesis and measurement of the binary alloy 87.8Al-12.2Si (at%) and ternary alloy 45Al-40Si-15Fe (at%). The metallic alloy is synthesized by hot pressing method. The latent heat of fusion of 45Al-40Si-15Fe (at%) is about 865 kJ/kg with melting temperature from 830 °C to 890 °C from the differential scanning calorimetry (DSC) measurement, comparing with 554.9 kJ/kg and 578.3 °C for the binary alloy 87.8Al-12.2Si (at%). From the binary to the ternary alloy, the contribution to the latent heat from mixing entropy increases by 17%.

Nano-Phase Change Materials for Electronics Cooling Applications

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Laura Colla ◽  
Davide Ercole ◽  
Laura Fedele ◽  
Simone Mancin ◽  
Oronzio Manca ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Phase Change ◽  
Specific Heat ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Melting Time ◽  
Numerical Comparison ◽  
Al2o3 Nanoparticles ◽  
Paraffin Waxes

The present work aims at investigating a new challenging use of aluminum oxide (Al2O3) nanoparticles to enhance the thermal properties (thermal conductivity, specific heat, and latent heat) of pure paraffin waxes to obtain a new class of phase change materials (PCMs), the so-called nano-PCMs. The nano-PCMs were obtained by seeding 0.5 and 1.0 wt  % of Al2O3 nanoparticles in two paraffin waxes having melting temperatures of 45 and 55 °C, respectively. The thermophysical properties such as specific heat, latent heat, and thermal conductivity were then measured to understand the effects of the nanoparticles on the thermal properties of both the solid and liquid PCMs. Furthermore, a numerical comparison between the use of the pure paraffin waxes and the nano-PCMs obtained in a typical electronics passive cooling device was developed and implemented. A numerical model is accomplished to simulate the heat transfer inside the cavity either with PCM or nano-PCM. Numerical simulations were carried out using the ansys-fluent 15.0 code. Results in terms of solid and liquid phase fractions and temperatures and melting time were reported and discussed. They showed that the nano-PCMs determine a delay in the melting process with respect to the pure PCMs.

scholarly journals Nano-Enhanced Phase Change Materials in Latent Heat Thermal Energy Storage Systems: A Review

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3821
Author(s):  
Kassianne Tofani ◽  
Saeed Tiari
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Heat Pipes ◽  
Energy Storage Systems ◽  
Thermal Energy Storage Systems

Latent heat thermal energy storage systems (LHTES) are useful for solar energy storage and many other applications, but there is an issue with phase change materials (PCMs) having low thermal conductivity. This can be enhanced with fins, metal foam, heat pipes, multiple PCMs, and nanoparticles (NPs). This paper reviews nano-enhanced PCM (NePCM) alone and with additional enhancements. Low, middle, and high temperature PCM are classified, and the achievements and limitations of works are assessed. The review is categorized based upon enhancements: solely NPs, NPs and fins, NPs and heat pipes, NPs with highly conductive porous materials, NPs and multiple PCMs, and nano-encapsulated PCMs. Both experimental and numerical methods are considered, focusing on how well NPs enhanced the system. Generally, NPs have been proven to enhance PCM, with some types more effective than others. Middle and high temperatures are lacking compared to low temperature, as well as combined enhancement studies. Al2O3, copper, and carbon are some of the most studied NP materials, and paraffin PCM is the most common by far. Some studies found NPs to be insignificant in comparison to other enhancements, but many others found them to be beneficial. This article also suggests future work for NePCM and LHTES systems.

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