Research

21 pages, 7227 KiB

Open AccessArticle

Development and Characteristics Analysis of Novel Hydrated Salt Composite Adsorbents for Thermochemical Energy Storage

by Yihan Wang, Zicheng Zhang, Shuli Liu, Zhihao Wang and Yongliang Shen

Energies 2023, 16(18), 6572; https://doi.org/10.3390/en16186572 - 12 Sep 2023

Viewed by 809

New composite adsorbents are proposed to further improve the application of thermochemical energy storage technology in buildings. A volcanic is taken as an adsorption substance, which is impregnated in 36.50 wt% and 54.00 wt% saturated MgCl₂ and CaCl₂ solutions to prepare [...] Read more.

New composite adsorbents are proposed to further improve the application of thermochemical energy storage technology in buildings. A volcanic is taken as an adsorption substance, which is impregnated in 36.50 wt% and 54.00 wt% saturated MgCl₂ and CaCl₂ solutions to prepare composite adsorbents, which are called composite-MgCl₂ and composite-CaCl₂, respectively. According to the characterization, the main pore structure of the original volcanic is macropores (>100 nm), and hydrated salts tend to fill them. Compared with zeolite-MgCl₂, the final water uptake of composite-MgCl₂ and composite-CaCl₂ increased by 0.15 g/g and 0.03 g/g. Meanwhile, the TG-DSC measurement results show that the thermochemical energy storage densities of composite-MgCl₂ and composite-CaCl₂ are 1.02 and 1.56 times that of zeolite-MgCl₂, which are 642 kJ/kg and 983 kJ/kg, respectively. Moreover, the composition of the thermochemical energy storage densities of the composites is obtained by theoretical calculations, and the theoretically calculated results are close to the measured results. After several cycles, the composites still have high thermochemical energy storage capacity and low energy storage density cost. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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40 pages, 2879 KiB

Open AccessFeature PaperArticle

Engineering-Scale Integrated Energy System Data Projection Demonstration via the Dynamic Energy Transport and Integration Laboratory

by Ramon Yoshiura, Sarah Creasman and Aaron Epiney

Energies 2023, 16(16), 5878; https://doi.org/10.3390/en16165878 - 08 Aug 2023

Cited by 1 | Viewed by 752

Abstract

The objective of this study is to demonstrate and validate the Dynamic Energy Transport and Integration Laboratory (DETAIL) preliminary scaling analysis using Modelica language system-code Dymola. The DETAIL preliminary scaling analysis includes a multisystem integral scaling package between thermal-storage and hydrogen-electrolysis systems. To [...] Read more.

The objective of this study is to demonstrate and validate the Dynamic Energy Transport and Integration Laboratory (DETAIL) preliminary scaling analysis using Modelica language system-code Dymola. The DETAIL preliminary scaling analysis includes a multisystem integral scaling package between thermal-storage and hydrogen-electrolysis systems. To construct the system of scaled equations, dynamical system scaling (DSS) was applied to all governing laws and closure relations associated with the selected integral system. The existing Dymola thermal-energy distribution system (TEDS) facility and high-temperature steam electrolysis (HTSE) facility models in the Idaho National Laboratory HYBRID repository were used to simulate a test case and a corresponding scaled case for integrated system HYBRID demonstration and validation. The DSS projected data based on the test-case simulations and determined scaling ratios were generated and compared with scaled case simulations. The preliminary scaling analysis performance was evaluated, and scaling distortions were investigated based on data magnitude, sequence, and similarity. The results indicated a necessity to change the normalization method for thermal storage generating optimal operating conditions of 261 kW power and mass flow rate of 6.42 kg/s and the possibility of reselecting governing laws for hydrogen electrolysis to improve scaling predictive properties. To enhance system-scaling similarity for TEDS and HTSE, the requirement for scaling validation via physical-facility demonstration was identified. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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22 pages, 2151 KiB

Open AccessArticle

Numerical Study of a High-Temperature Latent Heat Thermal Energy Storage Device with AlSi₁₂ Alloy

by Chaomurilige, Geng Qiao, Peng Zhao, Yang Li and Yongliang Li

Energies 2023, 16(15), 5729; https://doi.org/10.3390/en16155729 - 31 Jul 2023

Viewed by 744

Abstract

This paper explores the potential of thermal storage as an energy storage technology with cost advantages. The study uses numerical simulations to investigate the impact of adding porous material to the HTF side during solidification to improve the heat transfer effect of TES [...] Read more.

This paper explores the potential of thermal storage as an energy storage technology with cost advantages. The study uses numerical simulations to investigate the impact of adding porous material to the HTF side during solidification to improve the heat transfer effect of TES using AlSi

_{12}

alloy as the phase-change material. The research also examines the effects of adding porous dielectric materials and increasing air velocity on the discharge temperature, discharge power, and discharge time of high-temperature phase-change energy storage systems. The study found that the temperature difference of the PCM (increased), solidification time (reduced more than 85%), the outlet temperature of the air, and heat discharge power of the LHS did not vary significantly across different porous materials (copper foam, nickel foam, and silicon carbide foam) added to the HTF tube. These findings offer important information for the design of high-temperature phase-change energy storage devices and can guide future developments in this field. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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16 pages, 6430 KiB

Open AccessArticle

Performance Analysis of Variable Cross-Section TEGs under Constant Heat Flux Conditions

by Junpeng Liu, Yajing Sun, Gang Chen and Pengcheng Zhai

Energies 2023, 16(11), 4473; https://doi.org/10.3390/en16114473 - 01 Jun 2023

Cited by 2 | Viewed by 857

Abstract

In this paper, five shapes of thermoelectric generator (TEG) models (cylindrical, barrel shaped, hourglass shaped, cup shaped, and inverse cup shaped) are built under the boundary conditions of heat flux at the hot end and convection at the cold end of the TEGs. [...] Read more.

In this paper, five shapes of thermoelectric generator (TEG) models (cylindrical, barrel shaped, hourglass shaped, cup shaped, and inverse cup shaped) are built under the boundary conditions of heat flux at the hot end and convection at the cold end of the TEGs. Based on the numerical simulation results, the configuration of the variable cross-section can effectively boost the performance of TEGs. Remarkably, the hourglass-shaped TEG generated the maximum output power and efficiency, which were 69.62% and 70.96% higher than that of the conventional cylindrical TEG, respectively. The results indicate that the hourglass shape is beneficial to enlarge the temperature difference between the two ends of the TEG, which results in performance improvement. In addition, the effects of heat flux and convection on the performance of TEGs are explored and discussed. After choosing the appropriate boundary conditions, the relationships between the maximum output power and efficiency and the shape factor of the hourglass-shaped TEG are obtained according to the fitting results. Finally, some conclusions are drawn to provide guidance for TEG applications. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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21 pages, 6109 KiB

Open AccessArticle

Performance Study on an Electrocaloric Heat Pump Based on Ga-Based Liquid Metal

by Panpan Song, Yawei Zhu, Zhongyan An, Mingshan Wei, Xiaoxia Sun and Yangjun Zhang

Energies 2023, 16(7), 3104; https://doi.org/10.3390/en16073104 - 29 Mar 2023

Cited by 1 | Viewed by 2251

Abstract

A solid-state heat pump using the electrocaloric effect (ECE) provides a new idea for the future development of heat pumps. However, most of the electrocaloric (EC) heat pumps presented in the literature are low in efficiency and use at least one moving part, [...] Read more.

A solid-state heat pump using the electrocaloric effect (ECE) provides a new idea for the future development of heat pumps. However, most of the electrocaloric (EC) heat pumps presented in the literature are low in efficiency and use at least one moving part, which significantly reduces the reliability of the heat pump and adds to its complexities. In this context, combining the positive and negative ECEs, we proposed a plate-laminar non-mobile EC heat pump adopting Gallium-based liquid metal as an intermediate medium to guarantee highly efficient heat transfer. Numerical simulation in COMSOL Multiphysics has been performed to investigate the correlation between different operating parameters and the performance of the EC heat pump. Changing the temperature span only, a COP of 8.13 and a UVHP of 746.1

W \cdot d m^{- 3}

were obtained at a temperature span of 7 K. It was also found that the UVHP increased by 28.45% and COP increased by 25.46% after adding one layer of EC material. The electric-induced quantity of heat and cooling capacity was found to significantly affect the heating performance. The biggest heating power of 7132.7

W \cdot d m^{- 3}

was obtained under 200

M V \cdot m^{- 1}

, and the biggest COP of 14.84 was obtained under 150

M V \cdot m^{- 1}

at a cyclic period of 8 s. This study provides a highly efficient, non-mobile EC heat pump that employs fluid-thermal conjugated heat transfer, and exploration of the parameters makes the optimization of the heat pump possible by fine-tuning the operation parameters. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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16 pages, 5763 KiB

Open AccessArticle

Optimizing the Transient Performance of Thermoelectric Generator with PCM by Taguchi Method

by Zhaochun Shi, Guohua Wang, Chunli Liu, Qiang Lv, Baoli Gong, Yingchao Zhang and Yuying Yan

Energies 2023, 16(2), 805; https://doi.org/10.3390/en16020805 - 10 Jan 2023

Cited by 4 | Viewed by 1245

Abstract

Phase change material (PCM) is an effective thermal management method to improve the thermoelectric conversion performance of a system. PCM can not only absorb excessive thermal energy at high temperature to protect the thermoelectric module (TEM) and increase the maximum available temperature range, [...] Read more.

Phase change material (PCM) is an effective thermal management method to improve the thermoelectric conversion performance of a system. PCM can not only absorb excessive thermal energy at high temperature to protect the thermoelectric module (TEM) and increase the maximum available temperature range, but also compensate for intermittent energy to extend the working time of the TEM. In the paper, the transient performance is improved by adding PCM to a traditional thermoelectric generator (TEG) system. Due to the low thermal conductivity of PCM, metal fins are used to improve the thermal conductivity of PCM. To achieve maximum efficiency of the TEG system, the Taguchi method is employed. Four factors are heat source thermal power, PCM type, height of the PCM box, and filling ratio of the PCM, respectively. The results show that heat source thermal power has the greatest effect, and PCM has the least effect on the conversion efficiency of the TEG system. Conversion efficiency from thermal to electricity is about 1.472% during 2300 s of the heating and cooling stages. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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Review

Jump to: Research, Other

19 pages, 2296 KiB

Open AccessEditor’s ChoiceReview

Comprehensive Review of Liquid Air Energy Storage (LAES) Technologies

by Ayah Marwan Rabi, Jovana Radulovic and James M. Buick

Energies 2023, 16(17), 6216; https://doi.org/10.3390/en16176216 - 27 Aug 2023

Cited by 1 | Viewed by 3000

Abstract

In recent years, liquid air energy storage (LAES) has gained prominence as an alternative to existing large-scale electrical energy storage solutions such as compressed air (CAES) and pumped hydro energy storage (PHES), especially in the context of medium-to-long-term storage. LAES offers a high [...] Read more.

In recent years, liquid air energy storage (LAES) has gained prominence as an alternative to existing large-scale electrical energy storage solutions such as compressed air (CAES) and pumped hydro energy storage (PHES), especially in the context of medium-to-long-term storage. LAES offers a high volumetric energy density, surpassing the geographical constraints that hinder current mature energy storage technologies. The basic principle of LAES involves liquefying and storing air to be utilized later for electricity generation. Although the liquefaction of air has been studied for many years, the concept of using LAES “cryogenics” as an energy storage method was initially proposed in 1977 and has recently gained renewed attention. With the growing need for alternative energy storage methods, researchers have increasingly explored the potential of cryogenic media, leading to the development of the first LAES pilot plant and a growing body of research on LAES systems. However, one notable drawback of LAES is its relatively low round-trip efficiency, estimated to be around 50–60% for large-scale systems. However, due to its thermo-mechanical nature, LAES offers versatility and can be easily integrated with other thermal energy systems or energy sources across a wide range of applications. Most of the existing literature on LAES focuses on thermodynamic and economic analyses, examining various LAES configurations, and there is a clear lack of experimental studies in this field. This paper aims to conduct a comprehensive review of LAES technology, with a focus on the performance enhancement of these systems. Future perspectives indicate that hybrid LAES solutions, incorporating efficient waste energy recovery sections, hold the most promise for enhancing the tech-no-economic performance of standalone LAES systems. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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28 pages, 2659 KiB

Open AccessReview

Advances in High-Temperature Molten Salt-Based Carbon Nanofluid Research

by Xia Chen, Mingxuan Zhang, Yuting Wu and Chongfang Ma

Energies 2023, 16(5), 2178; https://doi.org/10.3390/en16052178 - 24 Feb 2023

Cited by 4 | Viewed by 1830

Abstract

Molten salt is an excellent medium for heat transfer and storage. The unique microstructure of carbon nanomaterials leads to good mechanical stability, low density, high thermal conductivity, and high strength, etc. The addition of carbon nanomaterials to molten salt to form molten salt [...] Read more.

Molten salt is an excellent medium for heat transfer and storage. The unique microstructure of carbon nanomaterials leads to good mechanical stability, low density, high thermal conductivity, and high strength, etc. The addition of carbon nanomaterials to molten salt to form molten salt nanofluid can remarkably enhance the specific heat capacity and thermal conductivity of molten salt and reduce the molten salt viscosity, which is of great importance to increase the heat storage density and reduce the heat storage cost. Nevertheless, some challenges remain in the study of such nanofluids. The main challenge is the dispersion stability of carbon nanomaterials. Therefore, to improve research on carbon nanofluids, this paper summarizes the progress of carbon-based molten salt nanofluid research worldwide including the preparation methods of molten salt nanofluids, the improvement of heat transfer performance, and the improvement of heat storage performance. The effects of carbon nanoparticle concentration, size, and type on the heat transfer and storage performance of molten salt are derived, and the effects of nanoparticle shape on the heat transfer performance of molten salt are analyzed while more promising preparation methods for carbon-based molten salt nanofluids are proposed. In addition, the future problems that need to be solved for high-temperature molten salt-based carbon nanofluids are briefly discussed. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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Other

Jump to: Research, Review

12 pages, 3895 KiB

Open AccessBrief Report

Thermoelectric Field Analysis of Trapezoidal Thermoelectric Generator Based on the Explicit Analytical Solution of Annular Thermoelectric Generator

by Wei Niu and Xiaoshan Cao

Energies 2023, 16(8), 3463; https://doi.org/10.3390/en16083463 - 14 Apr 2023

Viewed by 869

Abstract

The geometrical configuration is one of the main factors that affect the thermoelectric performance of a device. Research on the trapezoidal thermoelectric generator (TTEG) with varied cross section is mainly based on finite element simulation and experiment. In this paper, an explicit analytical [...] Read more.

The geometrical configuration is one of the main factors that affect the thermoelectric performance of a device. Research on the trapezoidal thermoelectric generator (TTEG) with varied cross section is mainly based on finite element simulation and experiment. In this paper, an explicit analytical solution of the maximum output power of annular thermoelectric generators (ATEG) is proposed, which has been proved to have high accuracy. Then, the maximum output power between ATEG and TTEG is compared. Results show that, for the appropriate geometric parameter δ, the relative error of maximum output power between explicit analytical ATEG and the simulated solution of TTEG can reach the order of 10⁻³. When the hot end is at the a side, the high temperature and θ is 510 K and 10°, respectively. For Bi₂Te₃ material and PbTe material, the relative error of maximum output power between the explicit analytical and simulated solution is 0.0261% and 0.074%, respectively. Under suitable working conditions, the explicit analytical results of ATEG can provide some reference for the performance optimization of TTEG. Full article

(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)

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