Corrosion effect of phase change materials in solar thermal energy storage application

Summary In order to find phase change materials that can be better applied in the field of solar collectors, the phase change heat storage properties of urea (U) and ammonium bromide (AB) were studied. The eutectic ratio of UAB was found by the Edison method, and different additives were added to UAB by dipping and mixing. The structure and property of the composites were characterized by X‐ray powder diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry (DSC), and TG/TGA, respectively. The results showed that the eutectic ratio of UAB was 6:3; it was weakly acidic after melting not layered. When 6‐wt% EG and 1‐wt% nanometer titanium dioxide (TiO2) were added, the thermal conductivity of the material increased by 3.62 times; the thermal diffusivity was increased by 6.77 times. When the mass fraction of EG is between 1% and 6%, the larger the mass fraction of EG, the greater the thermal conductivity of the material. After 1000 cycles, the composite material performance was stable; at the same time, the used materials can be used as fertilizers to solve the problem of material pollution, which indicated that the prepared UAB/TiO2/EG composite PCMs had great application prospect in the field of solar collectors.

Section: Resultsmentioning

confidence: 99%

Section: Analysis Of Ph Testmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Preparation and characterization of urea/ammonia bromide composite phase change material

Liu

Zhang

et al. 2020

“…This can result in severe fouling and plugging in a circulating system. For more detailed corrosion behaviour studies between different container materials, molten salts, alloys, and liquid metals, readers can refer to Lai's book and the recently published review work by Vasu et al The past experience on the corrosivity of medium‐ and high‐temperature molten salts has concluded that: Containment materials of molten salt PCMs are selected primarily from iron‐ and nickel‐based stainless steels and high‐temperature alloys. Among them, stainless steel is the most widely used material and high‐temperature alloys commonly containing a high amount of chromium can help to avoid oxidation by forming a chromia film.…”

Section: Corrosivity and Stabilitymentioning

confidence: 99%

Medium- and high-temperature latent heat thermal energy storage: Material database, system review, and corrosivity assessment

Zhou¹,

Wu²

2018

105

Summary Latent heat thermal energy storage refers to the storage and recovery of the latent heat during the melting/solidification process of a phase change material (PCM). Among various PCMs, medium‐ and high‐temperature candidates are attractive due to their high energy storage densities and the potentials in achieving high round trip efficiency. Although a few review studies on high‐temperature PCMs have emerged in the past few years, the quantity, completeness, and accuracy of the presented data are relatively poor. Also, an efficient indexing methodology for retrieving useful PCM data is missing in the open literature. In this article, we created an up‐to‐date PCM database following a holistic review of the PCMs in medium‐ and high‐temperature applications over a temperature range of 100°C to 1680°C. Such effort then allows us to develop an accurate indexing tool for the fast selection of suitable PCM candidates and extraction of the related property data. More specifically, the created PCM database covers 496 entries of PCM materials, which are extracted from the scattered research works published during the year 1956 to 2017. The collected information includes both the basic thermo‐physical properties of PCMs (eg, melting temperature, heat of fusion, and thermal conductivity) and crucial design factors during construction and engineering phases (eg, energy storage density, volume expansion, liquid/solid densities, and cost). The reviewed PCMs comprise a wide variety of materials, including fluorides, chlorides, hydrates, nitrates, carbonates, metals and alloys, and other uncommon compounds and salts. In addition, the current work presents a brief review on high‐temperature latent heat thermal energy storage systems categorized into metallic and non‐metallic systems. The corrosivity and stability of PCMs, which are commonly ignored in previous studies, are also examined.

“…As mentioned before, PCM presents a liquid state when the temperature is above melting point, which may cause leakage from the tank and corrosion to the wall surfaces of the shell, especially for the material of salt hydrates belonging to inorganic kind . Most of the PCMs used in solar energy or other thermal domains are salt hydrates, because of moderate melting temperature and latent heat energy density.…”

Section: Introductionmentioning

confidence: 99%

Preparation and application of composite EG/Ba(OH)₂ ·8H₂ O form-stable phase change material for solar thermal storage

Han

Zhang

et al. 2019

Summary Composite expended graphite (EG)/Ba(OH)2·8H2O form‐stable phase change material (PCM) is prepared with porous adsorption method in this study to solve the problem of the leakage risk in the application process based on barium hydroxide octahydrate. In addition, the thermal properties and stability have been measured and verified. Thermal conductivity of each group composite material was enhanced by about two to four times, while the addition has little negative effect on the other properties. With microscopic features being characterized by scanning electron microscope (SEM), the experimental result demonstrates that the composite material with 7 wt% of EG is optimal to be a saturated state between two phases. After the thermal cyclings of 100, 300, and 500 times, thermal properties did not change dramatically, which can be used as an ideal material for solar thermal storage system within finite thermal cyclings. In order to simulate the operating condition of solar energy or waste heat storage, the composite material was encapsulated in the heat storage unit with pipe bundle, and heat storage/release experiences were performed to test the performance of the material and hot water supply. The results indicate that the composite material is qualified to storage and release sufficient heat. The experimental data can provide necessary technical reference for engineering design and effect prediction in practical application.