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Parrado, C., Caceres, G., Bize, F., Bubnovich, V., Baeyens, J., Degreve, J., et al. (2015). Thermo-mechanical analysis of copper-encapsulated NaNO3-KNO3. Chem. Eng. Res. Des., 93, 224–231.
Abstract: The present paper presents a numerical study to investigate and assess the heat transfer behavior of a copper and salt composite. A mixture of nitrates, KNO3-NaNO3, within a deformable spherical shell coating of copper will be used as an encapsulated phase change material, E-PCM. In the context of a thermo-mechanical analysis of this E-PCM, a simulation is proposed to determine its storage capacity and properties The melting, or solidification of the encapsulated PCM particles do not provoke cracking of the deformable shell. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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Zhang, H. L., Baeyens, J., Caceres, G., Degreve, J., & Lv, Y. Q. (2016). Thermal energy storage: Recent developments and practical aspects. Prog. Energy Combust. Sci., 53, 1–40.
Abstract: Thermal energy storage (TES) transfers heat to storage media during the charging period, and releases it at a later stage during the discharging step. It can be usefully applied in solar plants, or in industrial processes, such as metallurgical transformations. Sensible, latent and thermo-chemical media store heat in materials which change temperature, phase or chemical composition, respectively. Sensible heat storage is well-documented. Latent heat storage, using phase change materials (PCMs), mainly using liquid solid transition to store latent heat, allows a more compact, efficient and therefore economical system to operate. Thermo-chemical heat storage (TCS) is still at an early stage of laboratory and pilot research despite its attractive application for long term energy storage. The present review will assess previous research, while also adding novel treatments of the subject. TES systems are of growing importance within the energy awareness: TES can reduce the LCOE (levelized cost of electricity) of renewable energy processes, with the temperature of the storage medium being the most important parameter. Sensible heat storage is well-documented in literature and applied at large scale, hence limited in the content of the present review paper. Latent heat storage using PCMs is dealt with, specifically towards high temperature applications, where inorganic substances offer a high potential. Finally, the use of energy storage through reversible chemical reactions (thermo-chemical Storage, TCS) is assessed. Since PCM and TCS storage media need to be contained in a capsule (sphere, tube, sandwich plates) of appropriate materials, potential containment materials are examined. A heat transfer fluid (HTF) is required to convey the heat from capture, to storage and ultimate re-use. Particle suspensions offer a valid alternative to common HTF, and a preliminary assessment confirms the advantages of the upflow bubbling fluidized bed and demonstrates that particulate suspensions enable major savings in investment and operating costs. Novel treatments of the TES subject in the review involve the required encapsulation of the latent and chemical storage media, the novel development of powder circulation loops as heat transfer media, the conductivity enhancement of PCMs, the use of lithium salts, among others. (C) 2015 Elsevier Ltd. All rights reserved.
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Zhang, H. L., Baeyens, J., Degreve, J., Caceres, G., Segal, R., & Pitie, F. (2014). Latent heat storage with tubular-encapsulated phase change materials (PCMs). Energy, 76, 66–72.
Abstract: Heat capture and storage is important in both solar energy projects and in the recovery of waste heat from industrial processes. Whereas heat capture will mostly rely on the use of a heat carrier, the high efficiency heat storage needs to combine sensible and latent heat storage with phase change materials (PCMs) to provide a high energy density storage. The present paper briefly reviews energy developments and storage techniques, with special emphasis on thermal energy storage and the use of PCM. It thereafter illustrates first results obtained when encapsulating NaNO3/KNO3-PCM in an AISI 321 tube, as example of a storage application using a multi-tubular exchanger filled with PCM. To increase the effective thermal conductivity of the PCM, 2 inserts i.e. metallic foam and metallic sponge are also tested. Experimental discharging (cooling) rates are interpreted by both solving the unsteady-state conduction equation, and by using Comsol Multiphysics. Predictions and experimental temperature evolutions are in fair agreement, and the effect of the inserts is clearly reflected by the increased effective thermal conductivity of the insert-PCM composite. Application of Comsol to predict the mechanical behavior of the system, when melting and associated expansion increase the internal pressure, demonstrates that the pressure build-up is far below the Young's modulus of the AISI 321 encapsulation and that this shell will not crack (C) 2014 Elsevier Ltd. All rights reserved.
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