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Inorganic salt hydrates as Phase Change Materials (PCM) for thermal energy storage in solar installations

Styś-Maniara Marta, Nartowska Edyta, Metryka-Telka Monika, Porowski Rafał

Structure and Environment

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2022

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Vol. 14, no. 4

161--172

EN

The authors present a general idea of using inorganic salt hydrates in solar installations. A key role in this selection is played by thermophysical parameters, so the authors review their test methods and in turn characterize them for the most promising salt hydrates. Next, the authors describe the advantages and disadvantages of inorganic salt hydrates and indicate possibilities for their improvement. The use of salt hydrate converters in PV installations significantly improves the efficiency of photovoltaic modules. We show that at least 18 salt hydrates are promising for solar applications with the best ones being Sodium Hydrogen Phosphate Dodecahydrate, Sodium Carbonate Decahydrate and Calcium Chloride Hexahydrate. The selection of a test method for determining the thermophysical parameters of salt hydrates should be individual depending on the research objective. Comparing the methods presented, we believe that it is the DSC and DTA methods that provide the most accurate and repeatable results.

PL

Autorzy przedstawiają ogólną koncepcję wykorzystania nieorganicznych hydratów solnych w instalacjach solarnych. Kluczową rolę w tym doborze odgrywają parametry termofizyczne, dlatego autorzy dokonują przeglądu metod ich badania i kolejno charakteryzują je dla najbardziej obiecujących hydratów solnych i ich mieszanin. Następnie autorzy opisują zalety i wady nieorganicznych hydratów solnych oraz wskazują możliwości ich udoskonalenia. Zastosowanie konwerterów hydratów solnych w instalacjach PV znacząco poprawia sprawność modułów fotowoltaicznych. Wykazano, że co najmniej 18 hydratów soli i ich mieszanin jest obiecujących dla zastosowań solarnych ze względu na korzystne parametry termofizyczne, przy czym najlepsze z nich to dodekahydrat wodorofosforan sodu, dekahydrat węglanu sodu i heksadydrat chlorku wapnia. Z przeglądu literatury wynika, że wybór metody badawczej do określenia parametrów termofizycznych hydratów soli powinien być indywidualny w zależności od celu badań. Porównując przedstawione metody, stwierdzono, że to właśnie metody DSC i DTA dają najbardziej dokładne i powtarzalne wyniki.

2

Hybrid nano improved phase change material for latent thermal energy storage system: Numerical study

Benlekkam Mohamed Lamine, Nehari Driss

Archive of Mechanical Engineering

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2022

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LXIX, nr 1

77--98

EN

The phase change materials (PCM) are widely used in several applications, especiallyi n the latent heat thermal energy storage system (LHTESS). Due to the very low thermal conductivity of PCMs. A small mass fraction of hybrid nanoparticles TiO 2–CuO (50%–50%) is dispersed in PCM with five mass concentrations of 0%, 0.25%, 0.5%, 0.75% and 1 mass % to improve its thermal conductivity. This article is focused on thermal performance of the hybrid nano-PCM (HNPCM) used for the LHTESS. A numerical model based on the enthalpy-porosity technique is developed to solve the Navier-Stocks and energy equations. The computations were conducted for the melting and solidification processes of the HNPCM in a shell and tube latent heat storage (LHS). The developed numerical model was validated successfully with experimental data from the literature. The results showed that the dispersed hybrid nanoparticles improved the effective thermal conductivity and density of the HNPCM. Accordingly, when the mass fraction of a HNPCM increases by 0.25%, 0.5%, 0.75% and 1 mass %, the average charging time improves by 12.04 %, 19.9 %, 23.55%, and 27.33 %, respectively. Besides, the stored energy is reduced by 0.83%, 1.67%, 2.83% and 3.88%, respectively. Moreover, the discharging time was shortened by 18.47%, 26.91%, 27.71%, and 30.52%, respectively.

3

Towards development of a prototype high-temperature latent heat storage unit as an element of a RES-based energy system (part 2)

Karwacki J., Bogucka-Bykuć K., Włosiński W., Bykuć S.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2016

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Vol. 64, nr 2

401--408

EN

This paper presents an experimental study performed with the general aim of defining procedures for calculation and optimization of shell-and-tube latent thermal energy storage unit with metals or metal alloys as PCMs. The experimental study is focused on receiving the exact information about heat transfer between heat transfer fluid (HTF) and phase change material (PCM) during energy accumulation process. Therefore, simple geometry of heat transfer area was selected. Two configurations of shell-and-tube thermal energy storage (TES) units were investigated. The paper also highlights the emerging trend (reflected in the literature) with respect to the investigation of metal PCM-based heat storage units in recent years and shortly presents unique properties and application features of this relatively new class of PCMs.