scholarly journals Constant-volume vapor-liquid equilibrium for thermal energy storage: Generalized analysis of pure fluids

2020 ◽  
Vol 197 ◽  
pp. 01001
Author(s):  
Abdullah Bamoshmoosh ◽  
Gianluca Valenti
Keyword(s):  
Energy Storage ◽  
Energy Density ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Capacity ◽  
High Energy ◽  
Constant Volume ◽  
Temperature Range ◽  
Energy Storage Capacity ◽  
Vapor Liquid

Thermal energy storage is of great interest both for the industrial world and for the district heating and cooling sector. Available technologies present drawbacks that reduce the margin of application, such as low energy density, limited temperature range of work, and investment costs. Phase transition is one of the main phenomena that can be exploited for thermal energy storage because of its naturally high energy density. Constant-volume vapor-liquid transition shows higher flexibility and increased heat transfer properties with respect to available technologies. This work presents a description of the behavior of these types of systems. The analysis is carried out through a generalized approach using the Corresponding State Principle. Variation of internal energy as a function of temperature over a fixed range is calculated at constant volume at different values of specific volume. It is shown that, for lower specific volumes, larger temperature ranges of work can be achieved without occurring in the steep pressure increase typically given by the expansion of liquid. Maximum operating temperature range is increased by up to 20% of the critical temperature with minimal energy loss. In optimal subsets of these ranges of temperature, the energy storage capacity of vapor-liquid systems increases at lower volumes, with energy storage capacity increasing to up to 40% with a 50% increase of the reduced volume. This is especially valid for more complex fluids, which are more interesting for these applications because of their higher heat capacity.

Towards High Energy Density, High Conductivity Thermal Energy Storage Composites

2012 ◽  
Author(s):  
Patrick J. Shamberger ◽  
Daniel E. Forero
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Energy Density ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Energy ◽  
High Energy Density ◽  
Lithium Nitrate ◽  
Nitrate Trihydrate ◽  
Graphitic Foam

Thermal energy storage (TES) materials absorb transient pulses of heat, allowing for rapid storage of low-quality thermal energy for later use, and effective temperature regulation as part of a thermal management system. This paper describes recent development of salt hydrate-based TES composites at the Air Force Research Laboratory. Salt hydrates are known to be susceptible to undercooling and chemical segregation, and their bulk thermal conductivities remain too low for rapid heat transfer. Here, we discuss recent progress towards solving these challenges in the composite system lithium nitrate trihydrate/graphitic foam. This system takes advantage of both the high volumetric thermal energy storage density of lithium nitrate trihydrate and the high thermal conductivity of graphitic foams. We demonstrate a new stable nucleation agent specific to lithium nitrate trihydrate which decreases undercooling by up to ∼70% relative to previously described nucleation agents. Furthermore, we demonstrate the compatibility of lithium nitrate trihydrate and graphitic foam with the addition of a commercial nonionic silicone polyether surfactant. Finally, we show that thermal conductivity across water-graphite interfaces is optimized by tuning the surfactant concentration. These advances demonstrate a promising route to synthesizing high energy density, high thermal conductivity TES composites.

scholarly journals Mg-Based Hydrogen Absorbing Materials for Thermal Energy Storage—A Review

2018 ◽  
Vol 8 (8) ◽  
pp. 1375 ◽  
Author(s):  
Bo Li ◽  
Jianding Li ◽  
Huaiyu Shao ◽  
Liqing He
Keyword(s):  
Energy Storage ◽  
Energy Density ◽  
Energy Loss ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
High Energy ◽  
Low Energy ◽  
Potential Candidate ◽  
Chemical Heat

Utilization of renewable energy such as solar, wind, and geothermal power, appears to be the most promising solution for the development of sustainable energy systems without using fossil fuels. Energy storage, especially to store the energy from fluctuating power is quite vital for smoothing out energy demands with peak/off-peak hour fluctuations. Thermal energy is a potential candidate to serve as an energy reserve. However, currently the development of thermal energy storage (TES) by traditional physical means is restricted by the relatively low energy density, high temperature demand, and the great thermal energy loss during long-period storage. Chemical heat storage is one of the most promising alternatives for TES due to its high energy density, low energy loss, flexible temperature range, and excellent storage duration. A comprehensive review on the development of different types of Mg-based materials for chemical heat storage is presented here and the classic and state-of-the-art technologies are summarized. Some related chemical principles, as well as heat storage properties, are discussed in the context. Finally, some dominant factors of chemical heat storage materials are concluded and the perspective is proposed for the development of next-generation chemical heat storage technologies.

scholarly journals Crystal Transition Behavior and Thermal Properties of Thermal-Energy-Storage Copolymer Materials with N-Behenyl Side-Chain

2019 ◽  
Author(s):  
Yuchen Mao ◽  
Jin Gong ◽  
Meifang Zhu ◽  
Hiroshi Ito
Keyword(s):  
Thermal Properties ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Capacity ◽  
Synthesis Method ◽  
Side Chain ◽  
Monomer Ratio ◽  
Energy Storage Capacity ◽  
Crystal Transition

In this paper, we synthesized MC(BeA-co-MMA) copolymer microcapsules through suspension polymerization. The pendent n-behenyl group of BeA is highly crystalline, and it acts as the side-chain in the structure of BeA-co-MMA copolymer. The highly crystalline n-behenyl side-chain provides BeA-co-MMA copolymer thermal-energy-storage capacity. In order to investigate the correlation between thermal properties and crystal structure of BeA-co-MMA copolymer, the effects of monomer ratio, temperature changing and changing rate, as well as synthesis method were discussed. The monomer ratio influenced crystal transition behavior and thermal properties greatly. The DSC results proved that when the monomer ratio of BeA and MMA was 3:1, MC(BeA-co-MMA)3 showed the highest average phase change enthalpy ΔH (105.1 J·g–1). It indicated that the n-behenyl side-chain formed relatively perfect crystal region, which ensured a high energy storage capacity of copolymer. All the DSC and SAXS results proved that the amount of BeA had a strong effect on the thermal-energy-storage capacity of copolymer and the long spacing of crystals, but barely on the crystal lamella. It was found that MMA units worked like defects in the n-behenyl side-chain crystal structure of BeA-co-MMA copolymer. Therefore, a lower fraction of MMA, that is, a higher fraction of BeA contributed to a higher crystallinity of BeA-co-MMA copolymer for providing a better energy storage capacity and thermoregulation property. ST(BeA-co-MMA) copolymer sheets with the same ingredients as microcapsules were also prepared through light-induced polymerization aiming at clarifying the effect of synthesis method. The results proved that synthesis method mainly influenced the copolymer chemical component, but lightly on the crystal packing of n-behenyl side-chain.

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