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Journal ArticleDOI

Latent heat storage above 120°C for applications in the industrial process heat sector and solar power generation

10 Mar 2008-International Journal of Energy Research (John Wiley & Sons, Ltd.)-Vol. 32, Iss: 3, pp 264-271
TL;DR: In this paper, phase change materials (PCMs) are used for thermal storage in the temperature range of 120-300 °C for solar thermal power generation and high temperature process heat.
Abstract: This paper is focussed on thermal storage technologies using phase change materials (PCMs) in the temperature range of 120-300 °C for solar thermal power generation and high temperature process heat. As state-of-the-art reference system a steam accumulator is described, which typically has a volume-specific thermal energy density of 20-30 kWh/m³. Regarding efficiency, a fundamental demand on thermal storage is the minimization of temperature differences between working fluid and storage medium. This requires isothermal storage systems for processes using water/steam. An obvious solution is, therefore, the application of PCMs. The selection of the PCMs depends strongly on the operation conditions of the respective application. At present, the main emphasis is directed to alkali metal nitrates and nitrites and their mixtures. For example, the eutectic mixture of the binary system KNO3-NaNO3 has been identified as an excellent system to be used for processes using saturated steam at around 25 bar. At around 5 bar the ternary system KNO3-NaNO2-NaNO3, commonly used as heat transfer fluid, can also be used as a PCM. To overcome the low thermal conductivity of the salt systems, approaches of increased surfaces area and increased thermal conductivity using expanded graphite (EG) have been investigated. Using EG/PCM-composites the effective thermal conductivity can be increased from below 0.5 W/(mK) to 3-20 W/(mK). Three design concepts have been developed. In the macro-encapsulated design, the PCM is enclosed in metal tubes, giving a short distance for heat transfer and increasing the heat transfer area. In the second design, the heat exchanger tubes are embedded in EG/PCM-composite storage material. The third design option uses graphite foils arranged perpendicularly onto the heat exchanger tubes and a suitable salt system filled in between. The upgrade of existing steam accumulators using these PCM concepts is also proposed.
Citations
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Journal ArticleDOI
TL;DR: In this article, a review of thermal energy storage system design methodologies and the factors to be considered at different hierarchical levels for concentrating solar power (CSP) plants is presented.

1,031 citations

Journal ArticleDOI
TL;DR: In this article, the state of the art in investigations and developments of high-temperature phase change materials perspective for storage thermal and a solar energy in the range of temperatures from 120 to 1000 °C.
Abstract: The development of energy saving technologies is very actual issue of present day. One of perspective directions in developing these technologies is the thermal energy storage in various industry branches. The review considers the modern state of art in investigations and developments of high-temperature phase change materials perspective for storage thermal and a solar energy in the range of temperatures from 120 to 1000 °C. The considerable quantity of mixes and compositions on the basis of fluorides, chlorides, hydroxides, nitrates, carbonates, vanadates, molybdates and other salts, and also metal alloys is given. Thermophysical properties of potential heat storage salt compositions and metal alloys are presented. Compatibility of heat storage materials (HSM) and constructional materials have found its reflection in the present work. Data on long-term characteristics of some HSMs in the course of repeated cycles of fusion and solidification are analyzed. Article considers also other problems which should be solved for creation of commercial high-temperature heat storage devices with use of phase change materials.

933 citations

Journal ArticleDOI
TL;DR: In this paper, an updated review of the state of technology and installations of several energy storage technologies were presented, and their various characteristics were analyzed, including their storage properties, current state in the industry and feasibility for future installation.

761 citations

Journal ArticleDOI
TL;DR: In this paper, the Advanced Research Projects Agency-Energy (ARPA-Energy) gave DE-AR0000471 and DE-ARM0000181 for the first time, respectively.
Abstract: United States. Advanced Research Projects Agency-Energy (Awards DE-AR0000471 and DE-AR0000181)

483 citations

Journal ArticleDOI
TL;DR: In this paper, a detailed review of research outcomes and recent technological advancements in the field of inorganic phase change materials is presented while focusing on providing solutions to the associated disadvantages of this class of PCMs.
Abstract: Latent heat energy storage system is one of the promising solutions for efficient way of storing excess thermal energy during low consumption periods. One of the challenges for latent heat storage systems is the proper selection of the phase change materials (PCMs) for the targeted applications. As compared to organic PCMs, inorganic PCMs have some drawbacks, such as corrosion potential and phase separation; however, there are available techniques to overcome or minimize these drawbacks. On the other hand, inorganic PCMs are found to have higher thermal conductivity and storage capacity over organic PCMs. As a result inorganic PCMs have a great potential in thermal energy storage field, especially in medium to high temperature applications where organic PCMs are not a viable option. In this study, a detailed review of research outcomes and recent technological advancements in the field of inorganic phase change materials is presented while focusing on providing solutions to the associated disadvantages of this class of PCMs. Long term stability, thermal cycling performance, and heat transfer enhancements are also discussed in the context of this review.

450 citations

References
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ReportDOI
01 Apr 1979
TL;DR: In this article, the authors provided selected data with value judgements for an additional set of 107 salt systems of interest as candidate materials for thermal energy storage sub-systems, for electrochemical energy storage systems, and in electrochemical aluminum production.
Abstract: The present work provides selected data with value judgements for an additional set of 107 salt systems of interest as candidate materials for thermal energy storage sub-systems, for electrochemical energy storage systems, and in electrochemical aluminum production The physical properties assessed are: melting points; phase diagrams; eutectic compositions; density; surface tension; viscosity; electrical conductivity; diffusion constants for ions; heat of fusion; heat capacity; volume change on fusion; vapor pressure; thermal conductivity (liquid and solid); and cryoscopic constant The status of corrosion studies in the form of annotated bibliographic summaries, and salient observations on safety and hazards are also reported A summarizing series of tables is provided as index to the data-gaps status for this set of candidate materials

298 citations

Journal ArticleDOI
TL;DR: In this article, the authors use steam accumulators for compensation of fast transients in insolation for solarthermal systems using steam as working medium and integrate latent heat storage material to increase the storage capacity.

141 citations