IEA SHC Task 42 / ECES Annex 29 WG A1: Engineering and Processing of PCMs, TCMs and Sorption Materials

An overview on the recent results on the engineering and characterization of sorption materials, PCMs and TCMs investigated in the working group WG A1 "Engineering and processing of TES materials" of IEA SHC Task 42 / ECES Annex 29 (Task 4229) entitled "Compact Thermal Energy Storage" is presented

Manufacture Techniques of Chitosan-Based Microcapsules to Enhance Functional Properties of Textiles

In recent years, the textile industry has been moving to novel concepts of products, which could deliver to the user, improved performances. Such smart textiles have been proven to have the potential to integrate within a commodity garment advanced feature and functional properties of different kinds. Among those functionalities, considerable interest has been played in functionalizing commodity garments in order to make them positively interact with the human body and therefore being beneficial to the user health. This kind of functionalization generally exploits biopolymers, a class of materials that possess peculiar properties such as biocompatibility and biodegradability that make them suitable for bio-functional textile production. In the context of biopolymer chitosan has been proved to be an excellent potential candidate for this kind of application given its abundant availability and its chemical properties that it positively interacts with biological tissue. Notwithstanding the high potential of chitosan-based technologies in the textile sectors, several issues limit the large-scale production of such innovative garments. In facts the morphologies of chitosan structures should be optimized in order to make them better exploit the biological activity; moreover a suitable process for the application of chitosan structures to the textile must be designed. The application process should indeed not only allow an effective and durable fixation of chitosan to textile but also comply with environmental rules concerning pollution emission and utilization of harmful substances. This chapter reviews the use of microencapsulation technique as an approach to effectively apply chitosan to the textile material while overcoming the significant limitations of finishing processes. The assembly of chitosan macromolecules into microcapsules was proved to boost the biological properties of the polymer thanks to a considerable increase in the surface area available for interactions with the living tissues. Moreover, the incorporation of different active substances into chitosan shells allows the design of multifunctional materials that effectively combine core and shell properties. Based on the kind of substances to be incorporated, several encapsulation processes have been developed. The literature evidences how the proper choices concerning encapsulation technology, chemical formulations, and process parameter allow tuning the properties and the performances of the obtained microcapsules. Furthermore, the microcapsules based finishing process have been reviewed evidencing how the microcapsules morphology can positively interact with textile substrate allowing an improvement in the durability of the treatment. The application of the chitosan shelled microcapsules was proved to be capable of imparting different functionalities to textile substrates opening possibilities for a new generation of garments with improved performances and with the potential of protecting the user from multiple harms. Lastly, a continuous interest was observed in improving the process and formulation design in order to avoid the usage of toxic substances, therefore, complying with an environmentally friendly approach

Microencapsulation of a fatty acid with Poly(melamine-urea-formaldehyde)

The main purpose of this study is to obtain leakage-free, thermally stable decanoic acid microcapsules (microPCMs) for thermal energy storage applications. Decanoic acid (capric acid) is an environmentally friendly fatty acid since it is obtained from vegetable and animal oils. MicroPCMs were prepared with different capsule wall materials via a one-step in situ polymerization technique. The properties of microencapsulated PCMs have been analyzed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analyzer (TGA), Fourier transform infrared (FTIR) spectra analysis and particle size analyzer. The microPCMs prepared using Poly(urea-formaldehyde) (PUF) exhibit higher heat capacities and the microPCMs prepared using Poly(melamine-formaldehyde) (PMF) exhibit higher thermal stabilities. In order to obtain microPCMs with better properties such as suitable latent heat and better heat resistance at high temperatures, we microencapsulated decanoic acid with Poly (melamine-urea-formaldehyde) (PMUF). Furthermore, the effects of surfactants on microPCMs with PMUF were investigated by SEM, a particle size analyzer, DSC, and TGA. The results show that the binary surfactant system was a suitable emulsifier for this process. We determined that the melting temperature was close to 33 C, the latent heat storage capacity was about 88 J/g, and the mean particle diameter was 0.28 µm for microPCMs with PMUF. We recommend decanoic acid microencapsulated with PMUF for thermally stable and leakage-free applications above 95 C. © 2014 Elsevier B.V. All rights reserved.111M614 Firat University Scientific Research Projects Management Unit: FEB2011/18We would like to thank The Scientific & Technical Research Council of Turkey (TUBITAK) (The Project Code: TUBITAK 111M614) and Research Projects Unit of Nigde University (The Project Code: FEB2011/18) for their financial support for this study. We also would like to thank the editorial board and the anonymous reviewers for their helpful and constructive comments and suggestions thatgreatly contributed to improve the quality of the paper

Polystyrene-based caprylic acid microencapsulation for thermal energy storage

In this study, caprylic (octanoic) acid microcapsules were synthesized with polystyrene shell material using the emulsion polymerization method. The influence of the type and concentration of the crosslinking agent on the phase-change properties of the microcapsules was examined. The structure and properties of the microcapsules have been characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). A second main contribution of this work is to investigate whether we could synthesize microcapsules with the same thermal properties during serial production. The effects of serial production on microencapsulated caprylic acid (microPCMs) have been investigated by thermal methods. The results show that reproducibility is an important parameter in the microencapsulation process. It was determined that when the synthesis amount is increased, we obtained lower efficiency in the microencapsulation of caprylic acid. © 2016 Elsevier B.V.111M614We would like to thank The Scientific & Technical Research Council of Turkey ( TUBITAK ) (The Project Code: TUBITAK 111M614 ) for financial support for this study. We would also like to thank Mr. Süleyman Konuklu for his technical help for this study. Finally, we would like to extend special thanks to the editor, Dr. Carl M. Lampert, and the anonymous reviewers for their constructive suggestions

Phase change material sandwich panels for managing solar gain in buildings

In this study, a phase change material (PCM) sandwich panel was developed and tested to evaluate the resulting decrease in heating and cooling loads of a test cabin in Adana, Turkey, where Mediterranean climate prevails. The panel was formed by a macropackage of microencapsulated PCM layer together with an insulation panel. Two different PCMs, with melting points 26°C and 23°C, were used in the panel. Temperature distribution in he cabin was measured for four different cases. In summer, the maximum average temperature reduction achieved in the cabin was 2.5°C when only the PCM was used. This corresponded to a summer cooling load reduction of 7%. In winter, the maximum average temperature increase achieved in the cabin was 2.2°C with the PCM sandwich panel. The winter heating load was decreased by 17%. Energies conserved in cooling and heating were calculated as 186 kWh/year and 206 kWh/year, respectively. Copyright © 2009 by ASME

Preparation of pentadecane/poly(melamine-urea-formaldehyde) microcapsules for thermal energy storage applications

Phase change materials (PCMs) with suitable melting ranges for thermal energy storage applications are alkanes, paraffins, fatty acids, eutectic mixtures, and inorganic PCMs. Paraffinic hydrocarbons and fatty acids with low solubility in water are usually the preferred candidates. Pentadecane, which is an alkane hydrocarbon with the chemical formula C15H32, was used as PCM in this study. The pentadecane was microencapsulated with a poly(melamine-urea-formaldehyde (MUF)) shell for thermal energy storage. Pentadecane/poly(MUF) microcapsules were prepared by in situ polymerization method. The morphological analysis of pentadecane microcapsules was analyzed with scanning electron microscopy (SEM). Thermal properties of microcapsulated pentadecane were determined by differential scanning calorimetry (DSC). The results demonstrated that pentadecane/PUF microcapsules were prepared successfully, and they offer proper phase transition temperature range (8.7°C and 8.1°C) and heat enthalpy values (84.5 and -88.2 kJ/kg) for thermal energy storage applications. According to the results, it was determined that pentadecane/poly(MUF) microcapsules have good potential for thermal energy storage applications. © 2019 John Wiley & Sons, Ltd

The Preparation and Characterization of Chitosan-Gelatin Microcapsules and Microcomposites with Fatty Acids as Thermal Energy Storage Materials

After cellulose, chitosan is the second-most-abundant natural resource and can be used as shell material during microencapsulation. In this study, chitosan-gelatin (CG) microcapsules and microcomposites containing either caprylic or decanoic acid were prepared according to the complex coacervation method and cross-linked by glutaraldehyde. To study the influence of the glutaraldehyde mass ratio upon encapsulation, as well as both the physical and thermal properties of the resulting microcapsules, the properties of microencapsulated phase-change materials (microPCMs) were analyzed by using scanning electron microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Results show the successful synthesis of microPCMs and melting temperatures of approximately 11.5 and 24.2°C with latent heat storage capacities of 79 and 73Jg-1 for microPCMs containing caprylic acid and those containing decanoic acid, respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Microcapsulation and macrocapsulation of phase change materials by emulsion co-polymerization method

In this study, decanoic acid suitable for thermal energy storage applicationswas microencapsulated with poly(styrene-co-ethyl acrylate) by emulsion copolymerizationmethod. Chemical structures, morphological characteristics, andthermal properties of microcapsules and macrocapsules were determined usingFourier Transfer Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy(SEM), and Differential Scanning Calorimeters (DSC) respectively. The microPCMsand macroPCMs were synthesized successfully and the encapsulation ratio wasabout up to 65.5 %. As a result, the as-prepared microcapsules show good potentialsfor thermal energy storage and could be used in many applications. © Springer International Publishing Switzerland 2015

Development of pentadecane/diatomite and pentadecane/sepiolite nanocomposites fabricated by different compounding methods for thermal energy storage

Global warming is one of the most important consequences of excess energy consumption. Phase change materials (PCMs) have prominent advantages in thermal energy storage owing to their high latent heat capacities and small temperature variations during the phase change process. However, leakage is a major problem that limits the use of PCMs. Leakage may occur in encapsulated PCMs or in composites where the PCM is attached to the surface of a supporting material or within the pores of that material. In this study, pentadecane/diatomite and pentadecane/sepiolite nanocomposites were fabricated by using unmodified and microwave-irradiated diatomite and sepiolite samples and by using different compounding processes, such as direct impregnation, vacuum impregnation, and ultrasonic-assisted impregnation methods. The microstructures and the chemical and thermal properties of the composites were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and differential scanning calorimetry. Subsequently, the thermal reliability and stability and the thermal conductivity of the PCM composites were also investigated. A melting temperature of 9.25°C and a latent heat capacity of 58.73 J/g were determined for the pentadecane/diatomite composite that was prepared with the direct impregnation method using a microwave-treated diatomite sample. The pentadecane/sepiolite composite prepared in the melting temperature range 7.98°C to 8.53°C and latent heat capacity range 41.05 to 46.02 J/g. The results of the thermal analysis indicate that fabricated diatomite-based or sepiolite-based PCM composites have good potential as thermal energy storage materials. © 2019 John Wiley & Sons, Ltd

Nanoencapsulation of n-alkanes with poly(styrene-co-ethylacrylate) shells for thermal energy storage

In this work, we synthesized a series of four nanocapsules containing n-alkanes (CnH2n+2), namely tetradecane, pentadecane, hexadecane, and heptadecane, in poly(styrene-co-ethylacrylate) using an emulsion copolymerization method. The nanocapsules were characterized according to their geometric profiles, phase transition temperatures, phase transition heats, mean particle sizes, and chemical stabilities by means of scanning electron microscopy, differential scanning calorimetry, thermal gravimetric analysis and Fourier transform infrared spectroscopy. Furthermore, we also focused on the effect of the core/shell mass ratio on the phase change properties of the nanocapsules. We found that microcapsules were synthesized successfully and that the best core/shell mass ratio was 3:1 for this study. These results indicate that encapsulated n-alkanes with poly(styrene-co-ethylacrylate) have an excellent potential for energy storage. © 2014 Elsevier Ltd.111M614We would like to thank The Scientic & Technical Research Council of Turkey (TUBITAK) (The Project Code: TUBITAK 111M614 ) for their financial support for this study. And also we would like to thank Mr. Suleyman Konuklu for his technical support for this study. Finally, we would like to extend special thanks to the editor and the anonymous reviewers for their constructive comments and suggestions in improving the quality of this paper