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21 pages, 11765 KiB

Open AccessFeature PaperArticle

Numerical Modeling of the Melting Process in a Shell and Coil Tube Ice Storage System for Air-Conditioning Application

by Seyed Soheil Mousavi Ajarostaghi, Sébastien Poncet, Kurosh Sedighi and Mojtaba Aghajani Delavar

Appl. Sci. 2019, 9(13), 2726; https://doi.org/10.3390/app9132726 - 05 Jul 2019

Cited by 35 | Viewed by 3675

Cold thermal energy storage, as a promising way of peak-shifting, can store energy by using cheap electricity during off-peak hours and regenerate electricity during peak times to reduce energy consumption. The most common form of cold storage air conditioning technology is ice on [...] Read more.

Cold thermal energy storage, as a promising way of peak-shifting, can store energy by using cheap electricity during off-peak hours and regenerate electricity during peak times to reduce energy consumption. The most common form of cold storage air conditioning technology is ice on the coil energy storage system. Most of the previous studies so far about ice on coil cold storage system have been done experimentally. Numerical modeling appears as a valuable tool to first better understand the melting process then to improve the thermal performance of such systems by efficient design. Hence, this study aims to simulate the melting process of phase change materials in an internal melt ice-on-coil thermal storage system equipped with a coil tube. A three-dimensional numerical model is developed using ANSYS Fluent 18.2.0 to evaluate the dynamic characteristics of the melting process. The effects of operating parameters such as the inlet temperature and flowrate of the heat transfer fluid are investigated. Also, the effects of the coil geometrical parameters—including coil pitch, diameter, and height—are also considered. Results indicate that conduction is the dominant heat transfer mechanism at the initial stage of the melting process. Increasing either the inlet temperature or the flowrate shortens the melting time. It is also shown that the coil diameter shows the most pronounced effect on the melting rate compared to the other investigated geometrical parameters. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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17 pages, 2131 KiB

Open AccessArticle

Edible Oils as Practical Phase Change Materials for Thermal Energy Storage

by Samer Kahwaji and Mary Anne White

Appl. Sci. 2019, 9(8), 1627; https://doi.org/10.3390/app9081627 - 19 Apr 2019

Cited by 49 | Viewed by 7355

Abstract

Edible oils could provide more accessible alternatives to other phase change materials (PCMs) for consumers who wish to build a thermal energy storage (TES) system with sustainable materials. Edible oils have good shelf life, can be acquired easily from local stores and can [...] Read more.

Edible oils could provide more accessible alternatives to other phase change materials (PCMs) for consumers who wish to build a thermal energy storage (TES) system with sustainable materials. Edible oils have good shelf life, can be acquired easily from local stores and can be less expensive than other PCMs. In this work, we explore whether margarine, vegetable shortening, and coconut oil are feasible PCMs, by investigations of their thermal properties and thermal stability. We found that margarine and vegetable shortening are not useful for TES due to their low latent heat of fusion, Δ_fusH, and poor thermal stability. In contrast, coconut oil remained thermally stable after 200 melt-freeze cycles, and has a large Δ_fusH of 105 ± 11 J g⁻¹, a low degree of supercooling and a transition temperature, T_mpt = 24.5 ± 1.5 °C, that makes it very useful for TES in buildings. We also determined coconut oil’s heat capacity and thermal conductivity as functions of temperature and used the measured properties to evaluate the feasibility of coconut oil for thermal buffering and passive heating of a residential-scale greenhouse. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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34 pages, 33809 KiB

Open AccessFeature PaperArticle

Efficient Characterization of Macroscopic Composite Cement Mortars with Various Contents of Phase Change Material

by Laurent Zalewski, Erwin Franquet, Stéphane Gibout, Pierre Tittelein and Didier Defer

Appl. Sci. 2019, 9(6), 1104; https://doi.org/10.3390/app9061104 - 15 Mar 2019

Cited by 14 | Viewed by 2851

Abstract

The determination of both the thermal and thermodynamical properties of a composite material containing phase change material is done thanks to an inverse method, which combines experimental measurements and numerical computations. Given first an in-house experiment, which allows us to test samples at [...] Read more.

The determination of both the thermal and thermodynamical properties of a composite material containing phase change material is done thanks to an inverse method, which combines experimental measurements and numerical computations. Given first an in-house experiment, which allows us to test samples at a macroscopic scale (i.e., close to the real conditions) and to set various types of thermal stresses, and secondly the simulation of the corresponding thermal behavior, relying on an accurate thermodynamical modeling and taking into account the real operating parameters (e.g., thermal contact resistances and non-symmetric heat fluxes on each side), it is possible to characterize the solid and liquid thermal conductivities and heat capacities, as well as the temperature range associated with a non-isothermal phase transition and the associated latent heat. The specificity of the present approach is to allow, in a single step, a characterization of all the involved thermo-physical parameters that are usually required in simulation tools (e.g., EnergyPlus…). Moreover, the hitherto studies dealing with repeatability and uncertainties of the enthalpy characterization are generally very scant and not encountered very often or only with qualitative assessments. This is a clear caveat, especially when considering any system design. Therefore, for the first time ever, the present paper pays a special attention to the repeatability of the identification method and studies the scedasticity of the results, that is to say the deviations of the determined enthalpy curves, not only from a qualitative point of view but also by proposing quantitative arguments. Finally, the results are very promising since the agreement between all trials is excellent, the maximum error for all parameters being lower than 4%. This is far below the current quality thresholds admitted when characterizing the enthalpy of a phase change material. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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21 pages, 4980 KiB

Open AccessArticle

Application of Hybrid PCM Thermal Energy Storages with and without Al Foams in Solar Heating/Cooling and Ground Source Absorption Heat Pump Plant: An Energy and Economic Analysis

by Renato Lazzarin, Marco Noro, Giulia Righetti and Simone Mancin

Appl. Sci. 2019, 9(5), 1007; https://doi.org/10.3390/app9051007 - 11 Mar 2019

Cited by 18 | Viewed by 4452

Abstract

The use of phase change materials (PCM) can be considered an effective way to improve the energy storage capabilities of hybrid water thermal energy storage (TESs) in solar heating and cooling plants. However, due to a few shortcomings, their use is still limited. [...] Read more.

The use of phase change materials (PCM) can be considered an effective way to improve the energy storage capabilities of hybrid water thermal energy storage (TESs) in solar heating and cooling plants. However, due to a few shortcomings, their use is still limited. This paper aims to give a direct estimation of the considerable advantages achievable by means of these hybrid TESs by simulating the annual performance of an existing gymnasium building located in northern Italy. The solar heating/cooling and ground source absorption heat pump plant is simulated using Trnsys. A validated type allows for the simulation of the hybrid water TESs, and also includes the possibility to use aluminum foams to enhance the heat transfer capabilities of the paraffin waxes used as PCM. This paper presents an optimization of the plant design from both energy and economic points of view by considering different cases: all three tanks modeled as sensible (water) storage, or one of the tanks modeled as PCM storage, or as enhanced PCM with metal foam. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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11 pages, 5176 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Cement Mortar Containing Phase Change Materials

by Hyun-Do Yun, Jong-Won Lee, Young-Il Jang, Seok-Joon Jang and Wonchang Choi

Appl. Sci. 2019, 9(5), 943; https://doi.org/10.3390/app9050943 - 06 Mar 2019

Cited by 17 | Viewed by 3605

Abstract

This paper presents an investigation of the characterization of cement mortar containing phase change materials (PCMs) in order to control the development of hydration heat. The study examined microstructural characteristics and properties of cement mortar with PCMs such as flow, compressive strength, and [...] Read more.

This paper presents an investigation of the characterization of cement mortar containing phase change materials (PCMs) in order to control the development of hydration heat. The study examined microstructural characteristics and properties of cement mortar with PCMs such as flow, compressive strength, and flexural strength. This research involved two types of PCM and up to 15% cement added to cement mortar mixtures. The two types of PCM used in this study are PCM with barium (PCM-Ba) and PCM with strontium (PCM-Sr). The experimental results indicate that both the incremental temperature rise and the maximum temperature release time of PCM up to 5% addition are delayed. Both PCM-Ba and PCM-Sr are effective in reducing the development of hydration heat. The microstructural analysis results show that the crystalloid content of cement mortar without PCMs is about 3% more from cement mortar with PCMs, regardless of the type of PCMs used, and that no significant difference is evident in the formation of crystals between cement mortar with and without PCMs. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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17 pages, 7448 KiB

Open AccessArticle

Passive Thermal Management of Tablet PCs Using Phase Change Materials: Intermittent Operation

by Tousif Ahmed, Maha Bhouri, Dominic Groulx and Mary Anne White

Appl. Sci. 2019, 9(5), 902; https://doi.org/10.3390/app9050902 - 03 Mar 2019

Cited by 15 | Viewed by 3087

Abstract

This paper presents an experimental study of thermal management in a tablet PC under intermittent operation, with phase change materials (PCMs) encapsulated in a very thin aluminized laminate film container. It complements a study of the same system under continuous operation that was [...] Read more.

This paper presents an experimental study of thermal management in a tablet PC under intermittent operation, with phase change materials (PCMs) encapsulated in a very thin aluminized laminate film container. It complements a study of the same system under continuous operation that was published in 2018. Two different types of PCMs were used for the experimental work; PT-37 and n-eicosane. A commercially available tablet PC was used as a test subject to ensure representative dimensions and material properties of every intricate part of the real tablet PC. For intermittent operation, the cycle used corresponds to fifteen minutes of operation (heat generation) followed by fifteen minutes of rest, to imitate a regular usage pattern of a tablet PC. It was observed that thin PCM thermal energy storage (TES) units are capable of providing a reduction in the rate of temperature increase during transient operations for both the electronics and the tablet cover. Reduction in peak temperature of the heat source and external surfaces of the tablet PC was also observed. At the maximum of 8 W operating power, PCMs were able to reduce the back-cover temperature by 20 °C. At all power inputs, heat storage in PCMs resulted in back-cover temperatures lower than 40 °C. Moreover, it was found that the PCM thermal management system tested was not affected by the inclination of the tablet PC. Results obtained from this study confirm that thin PCM encapsulation is indeed a suitable solution to control the temperature in tablet PCs during intermittent operation. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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11 pages, 3105 KiB

Open AccessArticle

Dual-Functional Nanoscale Devices Using Phase-Change Materials: A Reconfigurable Perfect Absorber with Nonvolatile Resistance-Change Memory Characteristics

by Niloufar Raeis-Hosseini and Junsuk Rho

Appl. Sci. 2019, 9(3), 564; https://doi.org/10.3390/app9030564 - 08 Feb 2019

Cited by 24 | Viewed by 4742

Abstract

Integration of metamaterial and nonvolatile memory devices with tunable characteristics is an enthusing area of research. Designing a unique nanoscale prototype to achieve a metasurface with reliable resistive switching properties is an elusive goal. We demonstrate a method to exploit the advantages of [...] Read more.

Integration of metamaterial and nonvolatile memory devices with tunable characteristics is an enthusing area of research. Designing a unique nanoscale prototype to achieve a metasurface with reliable resistive switching properties is an elusive goal. We demonstrate a method to exploit the advantages of a phase-change material (PCM) as a metamaterial light absorber and a nanoscale data storage device. We designed and simulated a metamaterial perfect absorber (MPA) that can be reconfigured by adjusting the visible light properties of a chalcogenide-based PCM. The suggested perfect absorber is based on a Ge₂Sb₂Te₅ (GST) film, and is tuned between two distinct states by heat treatment. Furthermore, we fabricated and characterized a resistive switching memory (ReRAM) device with the same features. The MPA/ReRAM device with a conventional metal/dielectric/metal structure (Ag/GST/Al₂O₃/Pt) consisted of arrays of Ag squares patterned on a GST thin film and an alumina-coated Pt mirror on a glass substrate. Based on the numerical data, amorphous GST showed perfect absorbance in the visible spectrum, whereas, crystalline GST showed broadband perfect absorbance. The fabricated ReRAM device exhibited uniform, bidirectional, and programmable memory characteristics with a high ON/OFF ratio for nonvolatile memory applications. The elucidated origin of the bipolar resistive switching behavior is assigned to the formation and rupture of conductive filaments. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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14 pages, 6743 KiB

Open AccessArticle

Impregnation of Wood with Microencapsulated Bio-Based Phase Change Materials for High Thermal Mass Engineered Wood Flooring

by Damien Mathis, Pierre Blanchet, Véronic Landry and Philippe Lagière

Appl. Sci. 2018, 8(12), 2696; https://doi.org/10.3390/app8122696 - 19 Dec 2018

Cited by 41 | Viewed by 6266

Abstract

Wood is a porous material that can be impregnated and have enhanced properties. Two species of hardwood, red oak (Quercus rubra L.) and sugar maple (Acer saccharum Marsh.), were impregnated in a reactor with a microencapsulated phase change material. The objective [...] Read more.

Wood is a porous material that can be impregnated and have enhanced properties. Two species of hardwood, red oak (Quercus rubra L.) and sugar maple (Acer saccharum Marsh.), were impregnated in a reactor with a microencapsulated phase change material. The objective was to enhance the thermal mass of wood boards used as surface layers for engineered wood flooring manufacturing. Preliminary experiments were conducted on small samples in order to define suitable impregnation parameters, based on the Bethell cycle. Thin wood boards were impregnated with a microencapsulated phase change material dispersed into distilled water. Several cycles of pressure were applied. Heating storage of the impregnated wood boards was determined using a dynamic heat flow meter apparatus method. A latent heat storage of 7.6 J/g over 3 °C was measured for impregnated red oak samples. This corresponds to a heat storage enhancement of 77.0%. Sugar maple was found to be harder to impregnate and thus his thermal enhancement was lower. Impregnated samples were observed by reflective optical microscopy. Microcapsules were found mainly in the large vessels of red oak, forming aggregates. Pull-off tests were conducted on varnished samples to assess the influence of an impregnation on varnish adhesion and no significant influence was revealed. Engineered wood flooring manufactured with impregnated boards such as characterized in this study could store solar energy and thus improve buildings energy efficiency. Although wood is a material with a low-conductivity, the thermal exchange between the PCM and the building air could be good enough as the microcapsules are positioned in the surface layer. Furthermore, flooring is an area with frequent sunrays exposure. Such high thermal mass EWF could lead to energy savings and to an enhancement of occupant’s thermal comfort. This study aimed to characterize the potential of impregnation with MPCM of two wood species in order to make high thermal mass EWF. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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Review

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26 pages, 5505 KiB

Open AccessReview

A Review of Germanium-Antimony-Telluride Phase Change Materials for Non-Volatile Memories and Optical Modulators

by Pengfei Guo, Andrew M. Sarangan and Imad Agha

Appl. Sci. 2019, 9(3), 530; https://doi.org/10.3390/app9030530 - 04 Feb 2019

Cited by 153 | Viewed by 15777

Abstract

Chalcogenide phase change materials based on germanium-antimony-tellurides (GST-PCMs) have shown outstanding properties in non-volatile memory (NVM) technologies due to their high write and read speeds, reversible phase transition, high degree of scalability, low power consumption, good data retention, and multi-level storage capability. However, [...] Read more.

Chalcogenide phase change materials based on germanium-antimony-tellurides (GST-PCMs) have shown outstanding properties in non-volatile memory (NVM) technologies due to their high write and read speeds, reversible phase transition, high degree of scalability, low power consumption, good data retention, and multi-level storage capability. However, GST-based PCMs have shown recent promise in other domains, such as in spatial light modulation, beam steering, and neuromorphic computing. This paper reviews the progress in GST-based PCMs and methods for improving the performance within the context of new applications that have come to light in recent years. Full article

(This article belongs to the Special Issue Advanced Applications of Phase Change Materials)

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