scholarly journals A Review on the Performance Indicators and Influencing Factors for the Thermocline Thermal Energy Storage Systems

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8384
Author(s):  
Wanruo Lou ◽  
Lingai Luo ◽  
Yuchao Hua ◽  
Yilin Fan ◽  
Zhenyu Du
Keyword(s):  
Energy Storage ◽  
Influencing Factors ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Performance Indicators ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Heat Transfer Fluid ◽  
Thermal Energy Storage Systems

Thermal energy storage (TES) system plays an essential role in the utilization and exploitation of renewable energy sources. Over the last two decades, single-tank thermocline technology has received much attention due to its high cost-effectiveness compared to the conventional two-tank storage systems. The present paper focuses on clarifying the performance indicators and the effects of different influencing factors for the thermocline TES systems. We collect the various performance indicators used in the existing literature, and classify them into three categories: (1) ones directly reflecting the quantity or quality of the stored thermal energy; (2) ones describing the thermal stratification level of the hot and cold regions; (3) ones characterizing the thermo-hydrodynamic features within the thermocline tanks. The detailed analyses on these three categories of indicators are conducted. Moreover, the relevant influencing factors, including injecting flow rate of heat transfer fluid, working temperature, flow distributor, and inlet/outlet location, are discussed systematically. The comprehensive summary, detailed analyses and comparison provided by this work will be an important reference for the future study of thermocline TES systems.

scholarly journals Investigation of the dynamic characteristics of a thermal energy storage unit filled with multiple phase change materials

2018 ◽  
Vol 22 (Suppl. 2) ◽  
pp. 527-533 ◽  
Author(s):  
Xiaoyan Li ◽  
Rongpeng Huang ◽  
Xinyue Miao ◽  
Xuelei Wang ◽  
Yabin Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Heat Transfer Fluid ◽  
Energy Storage Systems ◽  
Thermal Energy Storage Systems

In order to improve the thermal performance of thermal energy storage systems, a packed bed thermal energy storage systems unit using spherical capsules filled with multiple phase change materials (multi-PCM) for use in conventional air-conditioning systems is presented. A 3-D mathematical model was established to investigate the charging characteristics of the thermal energy storage systems unit. The optimum proportion between the multi-PCM was identified. The effects of heat transfer fluid-flow rate and heat transfer fluid inlet temperature on the liquid phase change materials volume fraction, charging time and charging capacity of the thermal energy storage system unit are studied. The results indicate that the charging capacity of multi-PCM units is higher than that of the conventional single-PCM (HY-2). For proportions 0:1:0, 2:3:3, 3:2:3, 3:3:2, 4:1:3, and 4:2:2, the charging capacity decreases by approximately 24.84%, 14.69%, 6.47%, 3.82%, and 1.13%, respectively, compared to the 4:2:2 proportion. Moreover, decreasing the heat transfer fluid inlet temperature can obviously shorten the complete charging time of the thermal energy storage systems unit.

scholarly journals Nano-Enhanced Phase Change Materials in Latent Heat Thermal Energy Storage Systems: A Review

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3821
Author(s):  
Kassianne Tofani ◽  
Saeed Tiari
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage Systems ◽  
Heat Pipes ◽  
Energy Storage Systems ◽  
Thermal Energy Storage Systems

Latent heat thermal energy storage systems (LHTES) are useful for solar energy storage and many other applications, but there is an issue with phase change materials (PCMs) having low thermal conductivity. This can be enhanced with fins, metal foam, heat pipes, multiple PCMs, and nanoparticles (NPs). This paper reviews nano-enhanced PCM (NePCM) alone and with additional enhancements. Low, middle, and high temperature PCM are classified, and the achievements and limitations of works are assessed. The review is categorized based upon enhancements: solely NPs, NPs and fins, NPs and heat pipes, NPs with highly conductive porous materials, NPs and multiple PCMs, and nano-encapsulated PCMs. Both experimental and numerical methods are considered, focusing on how well NPs enhanced the system. Generally, NPs have been proven to enhance PCM, with some types more effective than others. Middle and high temperatures are lacking compared to low temperature, as well as combined enhancement studies. Al2O3, copper, and carbon are some of the most studied NP materials, and paraffin PCM is the most common by far. Some studies found NPs to be insignificant in comparison to other enhancements, but many others found them to be beneficial. This article also suggests future work for NePCM and LHTES systems.

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