Experimental investigations on heat content of supercooled sodium acetate trihydrate by a simple heat loss method

Kong, Weiqiang; Dannemand, Mark; Berg, Jakob Brinkø; Fan, Jianhua; Dragsted, Janne; Englmair, Gerald; Furbo, Simon

doi:10.1016/j.solener.2016.09.045

Cited by 51 publications

(29 citation statements)

References 23 publications

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“…Each PCM unit was filled with a different SAT composite (Table 1), with the aim of investigating their stability in the system demonstration. Previous investigations [39] have shown the highest heat contents (Δh) when 1%wt of CMC (as in units 1 and 2) and 1%wt (unit 3) or 2%wt (unit 4) of EDTA were added to SAT. Unit 3 needed 1%wt extra water to achieve a fully dissolved solution during melting.…”

Section: Pcm Unitmentioning

confidence: 97%

“…Another way of reducing the problem of phase separation is to increase the solubility of the crystal water in the melted and supercooled SAT mixture. The heat contents of SAT composites with various concentrations of thickening agents, the chelating agent Disodium Ethylenediaminetetraacetic Acid (EDTA), and polymer additives have been investigated by Kong et al [39].…”

Section: Sodium Acetate Trihydrate Compositionsmentioning

confidence: 99%

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Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system

et al. 2018

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Document Version Peer reviewed versionLink back to DTU Orbit Citation (APA): Englmair, G., Moser, C., Furbo, S., Dannemand, M., & Fan, J. (2018). Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system. Applied Energy, 221, 522-534. https://doi. Highlights Combined short-and long-term heat-storage prototype for domestic solar heating  Interplay of solar collectors, four 200 kg PCM units and a 735 L water tank  Functionality of a segmented heat storage utilizing stable supercooling of SAT  Solidification of supercooled SAT was started by a seed crystal injection device  Supply temperatures and thermal power during PCM charge and discharge were evaluated Abstract A solar heating system with 22.4 m² of solar collectors, a heat storage prototype consisting of four 200 kg phase-change material (PCM) storage units, and a 735 L water tank was designed to improve solar heat supply in single-family houses. The PCM storage utilized stable supercooling of sodium acetate trihydrate composites to conserve the latent heat of fusion for long-term heat storage. A control strategy directed heat from a solar collector array to either the PCM storage or a water buffer storage. Several PCM units had to be charged in parallel when the solar collector output peaked at 16 kW. A single unit was charged with 27.4 kWh of heat within four hours on a sunny day, and the PCM temperature increased from 20 ºC to 80 ºC. The sensible heat from a single PCM unit was transferred to the water tankstarting with about 32 kW of thermal power after it had fully melted at 80 ºC. A mechanical seed crystal injection device was used to initialize the crystallisation of the sodium acetate trihydrate after it had supercooled to room temperature. The unit discharge during solidification peaked at 8 kW. Reliable supercooling was achieved in three of the four units. About 80% of latent heat of fusion was transferred from PCM units after solidification of supercooled sodium acetate trihydrate to the water tank within 5 hours. Functionality tests with practical operation conditions on the novel, modular heat-storage configuration showed its applicability for domestic hot water supply and space heating. Keywords: Solar heating system; heat storage prototype; phase change material; sodium acetate trihydrate; stable supercooling. P pump PCM phase-change material SA sodium acetate SAT sodium acetate trihydrate SH space heating V 2-way valve

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Section: Pcm Unitmentioning

confidence: 97%

Section: Sodium Acetate Trihydrate Compositionsmentioning

confidence: 99%

Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system

et al. 2018

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“…SAT is considered an incongruently melting salt hydrate, which suffers from phase separation. The problem of phase separation has been sought solved by adding thickeners or extra water to the SAT [7,8,[16][17][18][19][20]. The key properties, which determine the capacity of a PCM heat storage, are the specific heat capacity in solid and liquid phase, latent heat and the density of the PCM.…”

Section: Materials Propertiesmentioning

confidence: 99%

Porosity and density measurements of sodium acetate trihydrate for thermal energy storage

Dannemand

Delgado

Lázaro

et al. 2018

Applied Thermal Engineering

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Sodium acetate trihydrate (SAT) can be used as phase change material in latent heat storage with or without utilizing supercooling. The change of density between liquid to solid state leads to formation of cavities inside the bulk SAT during solidification. Samples of SAT which had solidified from supercooled state at ambient temperature and samples which had solidified with a minimal degree supercooled were investigated. The temperature dependent densities of liquid and the two types of solid SAT were measured with a density meter and a thermomechanical analyzer. The cavities formed inside samples of solid SAT, which had solidified after a high or minimal degree of supercooling, were investigated by X-ray scanning and computer tomography. The apparent density of solid SAT depended on whether it solidified from a supercooled state or not. A sample which solidified from a supercooled liquid contained 15% cavities and had a density of 1.26 g/cm 3 at 25 °C. SAT which had solidified with minimal supercooling contained 9% cavities and had a density of 1.34 g/cm 3 at 25 °C. The apparent densities of the solid SAT samples were significant lower than the value of solid SAT reported in literature of 1.45 g/cm 3. The density of liquid and supercooled SAT with extra water was also determined at different temperatures.

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“…Among which, DSP is an ideal nucleating agent considering the cost of the large-scale practical application of SAT compared with nanoparticles nucleating agents. Moreover, severe phase separation still occurs in SAT when the supercooling is lower [28]. Cabeza et al [29] showed that cellulose was the appropriate thickener compared with starch and bentonite.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Mechanism of Latent Heat Reduction of Sodium Acetate Trihydrate Phase Change Materials

Wang

et al. 2020

Materials

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Sodium acetate trihydrate (SAT) phase change material (PCM) has been well known for thermal energy storage due to its high latent heat and resource abundance. However, SAT suffers from severe latent heat reduction after heating and cooling cycles. Although a few of previous researches showed the reduction could be effectively inhibited by using thickeners, the mechanisms of the reduction process and thickeners’ inhibition have not been deeply explored till now. In this work, SAT modified by 5 wt.% nucleating agent of disodium hydrogen phosphate dodecahydrate (SAT/5 wt.% DSP) was prepared and 200 thermal cycles were carried out. The differential scanning calorimeter, Rheometer, X-ray diffractometry, and scanning electron microscope were used to investigate the extent of latent heat reduction, viscosity, phase composition and microstructure, respectively, and the infrared thermal imaging method was used to evaluate heat storage capacity. It was found that the latent heat of SAT/5 wt.% DSP dropped dramatically and the relative decrease in latent heat was measured to be 22.44%. The lower layer of SAT/5 wt.% DSP contained 24.1 wt.% CH3COONa, which was quantitatively consistent with the reduction extent. Furthermore, the phase change endothermic time of the lower layer was only 44.1% of that of the upper. SAT/5 wt.% DSP was further modified by 3 wt.% thickener of carboxymethyl cellulose (SAT/5 wt.% DSP/3 wt.% CMC) and endured 200 thermal cycles. The extent of the latent heat reduction of SAT/5 wt.% DSP/3 wt.% CMC was only 9.29%, and phase compositions were more homogeneous. The 3 wt.% CMC increased viscosity by 14 times, which effectively prevented the Stokes sedimentation velocity of CH3COONa in melts and inhibited the final macroscopic phase separation.

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Experimental investigations on heat content of supercooled sodium acetate trihydrate by a simple heat loss method

Cited by 51 publications

References 23 publications

Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system

Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system

Porosity and density measurements of sodium acetate trihydrate for thermal energy storage

Experimental Investigation on Mechanism of Latent Heat Reduction of Sodium Acetate Trihydrate Phase Change Materials

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