Optimized Salt Selection for Solar Thermal Latent Heat Energy Storage

Raud, Ralf; Bell, Stuart; Ong, Teng‐Cheong; Will, Geoffrey; Steinberg, Ted

doi:10.1002/adsu.201800074

Cited by 22 publications

(11 citation statements)

References 29 publications

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“…With regard to the accuracy of the predictive methods outlined in Section , in general, when comparing the error of the predicted values and the error of the published values from literature, they are on par with one another (see Tables S8 and S9 in the Supporting Information). This further validates the approach used in the optimization analysis used in the previous study to generate the list of recommended salt mixtures …”

Section: Discussionsupporting

confidence: 78%

“…This list of salts is for a single PCM application for TES. However, as mentioned in the previous study and as presented in Figure , an optimum design could utilize a cascaded storage system using five different PCMs . Potential further work could include testing more salts from the list of salts recommended in the previous optimization study for an additional four salts to create a cascaded storage system.…”

Section: Discussionmentioning

confidence: 96%

“…A significant proportion of eutectic salt combinations has not been tested and most of their thermophysical properties and their eutectic compositions are unknown or unpublished. Therefore, a systematic method of predicting the eutectic composition, melting temperature, and latent heat of fusion was performed for over 500 salt mixtures and presented in a previous study . In conjunction with a cost optimization analysis, this previous study was able to provide a comprehensive list of the best PCM candidates for selection criteria 1 and 2 (melting point and latent heat).…”

Section: Preliminary Selection Process Based On Theoretical/publishedmentioning

confidence: 99%

“…With the eutectic composition, melting temperature, and latent heat of fusion determinable for any salt combination using Gibbs diagrams and the aforementioned equations, a large list of possible salt combinations was incorporated into a cost optimization analysis . The results of this analysis yielded a comprehensive list of eutectic salts best suited for PCMs based on their thermal properties, and cost effectiveness when implemented in a finned tube heat exchanger.…”

Section: Preliminary Selection Process Based On Theoretical/publishedmentioning

confidence: 99%

“…Binary salt mixtures are diamonds, ternary are triangles, and quaternary mixtures are squares. Dotted line represents Sunshot target of $15 000 MWh −1 , all salts that fall below the line are potentially suitable PCM candidates …”

Section: Preliminary Selection Process Based On Theoretical/publishedmentioning

confidence: 99%

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High‐Temperature Phase Change Material (PCM) Selection for Concentrating Solar Power Tower Applications

Ong

Graham

Will

et al. 2018

Advanced Sustainable Systems

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reflect and concentrate sunlight onto a central receiver system that is situated at the top of a tower. This system is able to achieve higher operating temperatures at the receiver and much larger solar concentration ratios compared to parabolic trough systems, [2] resulting in higher thermodynamic efficiencies. [3] Several CSP tower plants are currently in successful operation, however they suffer from the same drawbacks as many renewable energy technologies in that their energy generation is intermittent. This is a major hindrance if renewable energy technologies are to compete with coal-fired power plants in providing baseload power to the grid. A solution to this for CSP plants is the use of thermal energy storage (TES) systems, in order to store thermal energy captured from sunlight for future use (during overcast weather conditions, or at night). [4] There are three types of TES systems. The first uses sensible heat (sensible heat thermal energy storage, SHTES), where a substance with a high heat capacity stores the thermal energy for future use. Typically, current operating plants (both parabolic and tower configurations) store thermal energy with molten solar salt-a combination of potassium nitrate and sodium nitrate. Energy is stored in or extracted from the solar salt by raising or lowering its temperature in response to the energy demand. These solar salts are limited by their maximum operating temperature of 585 °C and their energy storage capacity is determined by the heat capacity of the material. [5] The second TES system, latent heat thermal energy storage (LHTES), uses phase change materials (PCMs) that extract and store energy in the form of latent heat as the material transitions through a phase change (e.g., from solid to liquid). The energy of transformation is large, and therefore the storage material is able to charge and discharge significantly larger amounts of energy than sensible heat systems. This in turn improves the efficiency of the storage system, and occupies a smaller volume. Many PCMs can operate at much higher temperatures than sensible heat materials, which is a desirable property since the latest generation of CSP towers is capable of reaching temperatures in excess of 550 °C. [6,7] Additionally, the heat transfer process of extracting energy from PCMs is a relatively isothermal process, which translates to better temperature control and management of the entire heat transfer system that leads to higher efficiencies. [3,8] With current concerns about the environmental impact of greenhouse gas emissions, reducing our reliance on fossil fuels has become an ever-growing necessity. A thermal energy storage system that utilizes phase change materials (PCMs) in the form of molten salts, coupled with a concentrating solar power tower plant, is proposed as an effective means of achieving highly efficient and cost competitive power generation on par with traditional fossil fuel-based power. In this study, a set of five selection criteria are applied to a wide range of salt mixtures to...

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Section: Discussionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 96%

Section: Preliminary Selection Process Based On Theoretical/publishedmentioning

confidence: 99%

Section: Preliminary Selection Process Based On Theoretical/publishedmentioning

confidence: 99%

Section: Preliminary Selection Process Based On Theoretical/publishedmentioning

confidence: 99%

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