scholarly journals Enhancement of thermal properties of bio-based microcapsules intended for textile applications

2020 ◽  
Vol 18 (1) ◽  
pp. 669-680
Author(s):  
Virginija Skurkytė-Papievienė ◽  
Aušra Abraitienė ◽  
Audronė Sankauskaitė ◽  
Vitalija Rubežienė ◽  
Kristina Dubinskaitė
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Phase Change ◽  
Multiwall Carbon Nanotubes ◽  
Capric Acid ◽  
Test Method ◽  
Supplementary Information ◽  
Scanning Calorimetry ◽  
Ir Camera ◽  
The Core

AbstractThe thermal properties of bio-based phase change material (PCM) microcapsules and their separate components, core and shell, were investigated considering the influence of used thermal enhancer. As a core, bio-based PCM, capric acid (CA), was used. Biodegradable material, such as polylactic acid (PLA), was used as a shell. To improve the thermal conductivity of PLA/CA microcapsules, the multiwall carbon nanotubes (MWCNTs) were used as a thermal enhancer. Composites of PCM with different concentrations of MWCNT as well as composites of PLA with these carbon compounds were prepared and investigated to assess how MWCNT influences the thermal conductivity of the core and the shell. The heat storage and release capacity, as well as the phase change temperatures of CA/MWCNT composites and manufactured PCM microcapsules, were determined using differential scanning calorimetry. To evaluate the thermal conductivity of prepared composites and to compare it with the conductivity of pure materials (without MWCNT), their thermal resistance was measured using the guarded-hotplate test method. To obtain the supplementary information and to assess the dynamic behavior of used PCM during the temperature changes, another technique, such as monitoring of a cold/hot plate with an IR camera, was used. The results of these measurements showed that introduced MWCNT increases the thermal conductivity of PCM used for the core and the conductivity of films prepared from PLA. Consequently, with reference to the results obtained, it could be stated that the introduction of MWCNT into PLA/CA microcapsules improved the thermal properties of these microcapsules. However, it was determined that too large concentration of MWCNT reduces an enthalpy of melting and crystallization of tested PCM and PCM microcapsules. Therefore, during the investigation, an optimal concentration of MWCNT additives has been determined.

scholarly journals Demonstration of Phase Change Thermal Energy Storage in Zinc Oxide Microencapsulated Sodium Nitrate

2021 ◽  
Vol 11 (13) ◽  
pp. 6234
Author(s):  
Ciprian Neagoe ◽  
Ioan Albert Tudor ◽  
Cristina Florentina Ciobota ◽  
Cristian Bogdanescu ◽  
Paul Stanciu ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Thermal Properties ◽  
High Temperature ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Sodium Nitrate ◽  
Thermal Energy Storage ◽  
Metal Corrosion ◽  
Scanning Calorimetry

Microencapsulation of sodium nitrate (NaNO3) as phase change material for high temperature thermal energy storage aims to reduce costs related to metal corrosion in storage tanks. The goal of this work was to test in a prototype thermal energy storage tank (16.7 L internal volume) the thermal properties of NaNO3 microencapsulated in zinc oxide shells, and estimate the potential of NaNO3–ZnO microcapsules for thermal storage applications. A fast and scalable microencapsulation procedure was developed, a flow calorimetry method was adapted, and a template document created to perform tank thermal transfer simulation by the finite element method (FEM) was set in Microsoft Excel. Differential scanning calorimetry (DSC) and transient plane source (TPS) methods were used to measure, in small samples, the temperature dependency of melting/solidification heat, specific heat, and thermal conductivity of the NaNO3–ZnO microcapsules. Scanning electron microscopy (SEM) and chemical analysis demonstrated the stability of microcapsules over multiple tank charge–discharge cycles. The energy stored as latent heat is available for a temperature interval from 303 to 285 °C, corresponding to onset–offset for NaNO3 solidification. Charge–self-discharge experiments on the pilot tank showed that the amount of thermal energy stored in this interval largely corresponds to the NaNO3 content of the microcapsules; the high temperature energy density of microcapsules is estimated in the range from 145 to 179 MJ/m3. Comparison between real tank experiments and FEM simulations demonstrated that DSC and TPS laboratory measurements on microcapsule thermal properties may reliably be used to design applications for thermal energy storage.

scholarly journals Testing a Gypsum Composite Based on Raw Gypsum with a Direct Admixture of Paraffin and Polymer to Improve Thermal Properties

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3241
Author(s):  
Krzysztof Powała ◽  
Andrzej Obraniak ◽  
Dariusz Heim
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Phase Change ◽  
Large Scale ◽  
Building Materials ◽  
Residential Buildings ◽  
Energy Performance ◽  
Polymer Content ◽  
Volumetric Heat Capacity

The implemented new legal regulations regarding thermal comfort, the energy performance of residential buildings, and proecological requirements require the design of new building materials, the use of which will improve the thermal efficiency of newly built and renovated buildings. Therefore, many companies producing building materials strive to improve the properties of their products by reducing the weight of the materials, increasing their mechanical properties, and improving their insulating properties. Currently, there are solutions in phase-change materials (PCM) production technology, such as microencapsulation, but its application on a large scale is extremely costly. This paper presents a solution to the abovementioned problem through the creation and testing of a composite, i.e., a new mixture of gypsum, paraffin, and polymer, which can be used in the production of plasterboard. The presented solution uses a material (PCM) which improves the thermal properties of the composite by taking advantage of the phase-change phenomenon. The study analyzes the influence of polymer content in the total mass of a composite in relation to its thermal conductivity, volumetric heat capacity, and diffusivity. Based on the results contained in this article, the best solution appears to be a mixture with 0.1% polymer content. It is definitely visible in the tests which use drying, hardening time, and paraffin absorption. It differs slightly from the best result in the thermal conductivity test, while it is comparable in terms of volumetric heat capacity and differs slightly from the best result in the thermal diffusivity test.

scholarly journals Enhancement of the Thermal Performance of the Paraffin-Based Microcapsules Intended for Textile Applications

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1120
Author(s):  
Virginija Skurkyte-Papieviene ◽  
Ausra Abraitiene ◽  
Audrone Sankauskaite ◽  
Vitalija Rubeziene ◽  
Julija Baltusnikaite-Guzaitiene
Keyword(s):  
Thermal Conductivity ◽  
Thermal Performance ◽  
Comparative Method ◽  
Multiwall Carbon Nanotubes ◽  
Acrylic Resin ◽  
Positive Influence ◽  
Outer Shell ◽  
Ir Camera ◽  
Spacer Fabric ◽  
Thermally Conductive

Phase changing materials (PCMs) microcapsules MPCM32D, consisting of a polymeric melamine-formaldehyde (MF) resin shell surrounding a paraffin core (melting point: 30–32 °C), have been modified by introducing thermally conductive additives on their outer shell surface. As additives, multiwall carbon nanotubes (MWCNTs) and poly (3,4-ethylenedioxyoxythiophene) poly (styrene sulphonate) (PEDOT: PSS) were used in different parts by weight (1 wt.%, 5 wt.%, and 10 wt.%). The main aim of this modification—to enhance the thermal performance of the microencapsulated PCMs intended for textile applications. The morphologic analysis of the newly formed coating of MWCNTs or PEDOT: PSS microcapsules shell was observed by SEM. The heat storage and release capacity were evaluated by changing microcapsules MPCM32D shell modification. In order to evaluate the influence of the modified MF outer shell on the thermal properties of paraffin PCM, a thermal conductivity coefficient (λ) of these unmodified and shell-modified microcapsules was also measured by the comparative method. Based on the identified optimal parameters of the thermal performance of the tested PCM microcapsules, a 3D warp-knitted spacer fabric from PET was treated with a composition containing 5 wt.% MWCNTs or 5 wt.% PEDOT: PSS shell-modified microcapsules MPCM32D and acrylic resin binder. To assess the dynamic thermal behaviour of the treated fabric samples, an IR heating source and IR camera were used. The fabric with 5 wt.% MWCNTs or 5 wt.% PEDOT: PSS in shell-modified paraffin microcapsules MPCM32D revealed much faster heating and significantly slower cooling compared to the fabric treated with the unmodified ones. The thermal conductivity of the investigated fabric samples with modified microcapsules MPCM32D has been improved in comparison to the fabric samples with unmodified ones. That confirms the positive influence of using thermally conductive enhancing additives for the heat transfer rate within the textile sample containing these modified paraffin PCM microcapsules.

Synthesis and Thermal Properties of Magnesium Sulfate Heptahydrate/Urea Resin as Thermal Energy Storage Micro-Encapsulated Phase Change Material

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Chenzhen Liu ◽  
Ling Ma ◽  
Zhonghao Rao ◽  
Yimin Li
Keyword(s):  
Particle Size ◽  
Thermal Properties ◽  
Phase Change ◽  
Magnesium Sulfate ◽  
Phase Change Material ◽  
Core Material ◽  
Scanning Calorimetry ◽  
Sulfate Heptahydrate ◽  
Encapsulated Phase Change Material ◽  
Change Material

In this study, micro-encapsulated phase change material (microPCM) was successfully synthesized by emulsion polymerization method, using magnesium sulfate heptahydrate (MSH) as core material and urea resin (UR) as shell material. The surface morphologies and particle size distributions of the microPCM were tested by scanning electron microscopy (SEM) and laser particle size analyzer. The chemical structure of microPCM was analyzed by Fourier-transform infrared spectroscopy (FTIR). The thermal properties were investigated by differential scanning calorimetry (DSC) and thermal conductivity coefficient instrument, respectively.

scholarly journals Analysis of Bio-Based Fatty Esters PCM’s Thermal Properties and Investigation of Trends in Relation to Chemical Structures

2019 ◽  
Vol 9 (2) ◽  
pp. 225 ◽  
Author(s):  
Rebecca Ravotti ◽  
Oliver Fellmann ◽  
Nicolas Lardon ◽  
Ludger Fischer ◽  
Anastasia Stamatiou ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Phase Change ◽  
Energy Demand ◽  
Phase Change Materials ◽  
Arachidic Acid ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Fatty Esters ◽  
Latent Heat Storage ◽  
Chemical Structures

As global energy demand increases while primary sources and fossil fuels’ availability decrease, research has shifted its focus to thermal energy storage systems as alternative technologies able to cover for the mismatch between demand and supply. Among the different phase change materials available, esters possess particularly favorable properties with reported high enthalpies of fusion, low corrosivity, low toxicity, low supercooling, thermal and chemical stability as well as biodegradability and being derived from renewable feedstock. Despite such advantages, little to no data on the thermal behavior of esters is available due to low commercial availability. This study constitutes a continuation of previous works from the authors on the investigation of fatty esters as novel phase change materials. Here, methyl, pentyl and decyl esters of arachidic acid, and pentyl esters of myristic, palmitic, stearic and behenic acid are synthesized through Fischer esterification with high purities and their properties are studied. The chemical structures and purities are confirmed through Attenuated Total Reflectance Infrared Spectroscopy, Gas Chromatography coupled with Mass Spectroscopy and Nuclear Magnetic Resonance Spectroscopy, while the determination of the thermal properties is performed through Differential Scanning Calorimetry and Thermogravimetric Analysis. In conclusion, some correlations between the melting temperatures and the chemical structures are discovered, and the fatty esters are assessed based on their suitability as phase change materials for latent heat storage applications.

Study on a Novel Form-Stable Capric Acid/Organophilic Montmorillonite Composite for Thermal Energy Storage

2012 ◽  
Vol 271-272 ◽  
pp. 197-203
Author(s):  
Ting Wei ◽  
Zhen Wang ◽  
Bai Cun Zheng ◽  
Yan Feng Gao ◽  
Wei Hong Guo
Keyword(s):  
Thermal Properties ◽  
Energy Storage ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Capric Acid ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Excellent Thermal Stability ◽  
Organophilic Montmorillonite

A novel form-stable capric acid/organophilic montmorillonite composite for thermal energy storage is developed in this study. The morphology and thermal properties were determined by scanning electron microscope(SEM), polarized optical microscope(POM), differential scanning calorimetry(DSC) and thermogravimetric analyzer(TGA). The DSC results showed that the on-set temperature of the sample with 40% wt CA was closed to 29°C, the latent heat was 35.8 J/g at 56 kPa and 51.5 J/g at 0 kPa, while the on-set temperature of sample with 60% CA was also 29°C, the latent heat was 79.7 J/g at 56 kPa and 80.8 J/g at 0 kPa. TG investigations revealed that the composites had excellent thermal stability above their working temperature ranges. The POM images exhibited phase behaviors of composites to confirm leakage, and the samples with 20% and 40% CA showed good thermal properties. In addition, SEM images presented the microstructure of all the samples. All of the conclusions indicated that sample with 40% wt CA was a better candidate for novel form-stable CA/OMMT composite for low-temperature thermal energy storage applications.

scholarly journals Copper microsphere hybrid mesoporous carbon as matrix for preparation of shape-stabilized phase change materials with improved thermal properties

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yi Liu ◽  
Yan Chen ◽  
Junwei Zhang ◽  
Junkai Gao ◽  
Zhi Han
Keyword(s):  
Thermal Properties ◽  
Phase Change ◽  
Photoelectron Spectroscopy ◽  
Mesoporous Carbon ◽  
Phase Change Materials ◽  
Copper Ions ◽  
Thermal Constant ◽  
Step Method ◽  
Scanning Calorimetry ◽  
X Ray

Abstract Copper microsphere hybrid mesoporous carbon (MPC-Cu) was synthesized by the pyrolysis of polydopamine microspheres doped with copper ions that were prepared using a novel, facile and simple one-step method of dopamine biomimetic polymerization and copper ion adsorption. The resulting MPC-Cu was then used as a supporter for polyethylene glycol (PEG) to synthesize shape-stabilized phase change materials (PEG/MPC-Cu) with enhanced thermal properties. PEG/MPC-Cu was studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry and thermal constant analysis. The results demonstrated that the thermal conductivity of PEG/MPC-Cu was 0.502 W/(m K), which increased by 100% compared to pure PEG [0.251 W/(m K)]. The melting enthalpy of PEG/MPC-Cu was 95.98 J/g, indicating that PEG/MPC-Cu is a promising candidate for future thermal energy storage applications. In addition, the characterization results suggested that PEG-MPC-Cu possessed high thermal stability. Therefore, the method developed in this paper for preparing shape-stabilized phase change materials with improved thermal properties has substantial engineering application prospects.

scholarly journals Characterization of Thermophysical Properties of Phase Change Materials Using Unconventional Experimental Technologies

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4687
Author(s):  
Arnold Martínez ◽  
Mauricio Carmona ◽  
Cristóbal Cortés ◽  
Inmaculada Arauzo
Keyword(s):  
Thermal Properties ◽  
Phase Change ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Small Sample ◽  
Alternative Methods ◽  
Accurate Estimation ◽  
Inhomogeneous Materials ◽  
Scanning Calorimetry

The growing interest in developing applications for the storage of thermal energy (TES) is highly linked to the knowledge of the properties of the materials that will be used for that purpose. Likewise, the validity of representing processes through numerical simulations will depend on the accuracy of the thermal properties of the materials. The most relevant properties in the characterization of phase change materials (PCM) are the phase change enthalpy, thermal conductivity, heat capacity and density. Differential scanning calorimetry (DSC) is the most widely used technique for determining thermophysical properties. However, several unconventional methods have been proposed in the literature, mainly due to overcome the limitations of DSC, namely, the small sample required which is unsuitable for studying inhomogeneous materials. This paper presents the characterization of two commercial paraffins commonly used in TES applications, using methods such as T-history and T-melting, which were selected due to their simplicity, high reproducibility, and low cost of implementation. In order to evaluate the reliability of the methods, values calculated with the proposed alternative methods are compared with the results obtained by DSC measurements and with the manufacturer’s technical datasheet. Results obtained show that these non-conventional techniques can be used for the accurate estimation of selected thermal properties. A detailed discussion of the advantage and disadvantage of each method is given.

Microencapsulated Phase Change Materials and its Application in Thermal-Regulated Fibers

2012 ◽  
Vol 519 ◽  
pp. 6-9 ◽  
Author(s):  
Wei Li ◽  
Xing Xiang Zhang ◽  
Xue Chen Wang
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Formaldehyde Resin ◽  
Dsc Analysis ◽  
Melamine Formaldehyde ◽  
Scanning Calorimetry ◽  
The Core ◽  
Microencapsulated Phase Change Materials ◽  
Spinning Process ◽  
Alginate Fiber

The phase change materials (PCMs) can absorb, store or release large latent heat over a defined temperature range while the materials change phase or state, so they can be potentially used in thermal energy storage. In this paper, a series of microencapsulated phase change materials (MicroPCMs) with n-octadecane and n-dodecanol as core were successfully fabricated respectively, where the styrene-based copolymer, acrylic based copolymer, melamine-formaldehyde resin and polyurea were selected as shell materials. The morphology of these MicroPCMs was observed by scanning electron microscopy (SEM), and the core-shell structure and the shell thickness of microcapsules were also characterized by SEM. In addition, the phase change properties of MicroPCMs were investigated using differential scanning calorimetry (DSC) analysis. Furthermore, thermal-regulated calcium alginate fiber was produced by adding MicroPCMs in wet-spinning process; and the effects of various types of MicroPCMs on fiber was discussed.

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