Integrated Intelligent Energy

Review on solid particle thermal energy storage technology： Mechanisms， materials， devices and applications

ZHENG Hao, XIONG Yaxuan, QIAN Xiangyao, ZOU Jing, WU Yuting

2026, 48(6): 1-15. doi:10.3969/j.issn.2097-0706.2026.06.001

Asbtract ( 39 )

HTML ( 7)

PDF (1868KB) ( 15 )

Figures and Tables | References | Related Articles | Metrics

Against the backdrop of global low-carbon energy transition， the intermittency of renewable energy， the severe mismatch between energy supply and demand and other prominent energy challenges are positioning energy storage technology as a core support for renewable energy integration. Solid particle thermal energy storage technology has significant advantages， including a wide operating temperature range， stable thermal cycling， and environmental friendliness， showing great application potential in concentrated solar power， industrial waste heat recovery， and other fields. To clarify the application scenarios of different solid particle materials， the internal relationships are elucidated following the main line of "thermal energy storage mechanisms-solid particle materials-thermal energy storage devices-engineering applications"， whereby thermal energy storage mechanisms determine material adaptability， material properties constrain device structures， and device design supports practical applications. Solid particles can serve as media for four technical pathways： sensible heat storage（SHS）， latent heat storage（LHS）， thermochemical heat storage（TCHS）， and composite thermal energy storage（CTES）. The principles of each pathway， suitable typical particle materials， and their key thermophysical parameters are analyzed. SHS technology is mature but materials have low thermal density； LHS has higher thermal density and stable heat release， but materials face challenges like supercooling and encapsulation leakage； TCES materials have high thermal density but slow reaction rates， requiring gas processing systems which increase the initial investment； CTES materials have large interfacial thermal resistance but can improve system stability. The structures and working principles of three mainstream thermal energy storage devices—fixed beds， moving beds， and fluidized beds—are analyzed in depth. By clarifying the heat transfer correlation equations and characteristics （particle size， particle loss， and pressure drop） of different fluidized beds，the application scenarios and existing challenges of different devices are summarized. Specifically， packed beds are suitable for large particles， moving beds for medium particles， and fluidized beds for fine particles （e.g.， microencapsulated phase change and thermochemical particles）. By constructing a complete technical framework from materials to engineering implementation， the findings provide a technical basis for the rapid development and engineering application of solid particle thermal energy storage. Solid particle thermal energy storage technology will focus on high-value utilization of solid waste in terms of materials， optimization of bed structure and low-wear conveying technology in terms of devices， and integration of materials， devices， and intelligent monitoring platforms in terms of the whole thermal storage system in the future.

Research progress on concrete-based energy storage batteries

SHI Chuanqi, XIONG Yaxuan, HAN Chaoran, ZHENG Hao

2026, 48(6): 16-33. doi:10.3969/j.issn.2097-0706.2026.06.002

Asbtract ( 39 )

HTML ( 3)

PDF (4457KB) ( 20 )

Figures and Tables | References | Related Articles | Metrics

Concrete-based energy storage batteries embed electrochemical energy storage units into cement-based materials， enabling structural components to have electrical energy storage function in addition to their load-bearing role. It offers a novel material solution for building energy saving， renewable energy consumption， and infrastructure energization. Recent studies on concrete-based supercapacitors and concrete-based secondary batteries are summarized， covering material composition， structural configuration， performance evaluation， and application progress. The focus is placed on the coordination between energy storage performance and structural performance. Existing studies mainly focus on electrodes， electrolytes， separators， current collectors， and component structures. For electrodes， carbon black， carbon fibers， carbon nanotubes， and graphene can form conductive networks in cement matrices and are suitable for constructing electric double-layer capacitance systems. Metal oxides， metal hydroxides， metal nitrides， and conductive polymers can provide pseudocapacitive or battery-type reactions， contributing to increased capacity. However， their interfacial stability in alkaline pore solution and humid environments remains a challenge that needs to be addressed. In terms of fabrication， in-situ compounding facilitates integration with the concrete casting process. Electrochemical deposition can improve electrode surface activity. Template-assisted methods are beneficial for forming porous transport channels， and 3D printing enables the directional arrangement of electrodes and load-bearing regions. For electrolytes， liquid electrolytes have high ionic conductivity but are prone to leakage. Solid cement-based electrolytes provide better safety and load-bearing capacity but have insufficient transport efficiency. Gel electrolytes show relatively balanced performance in water retention， leakage resistance， and interfacial wetting. Separator materials also evolve from ordinary porous membranes toward cement-based and polymer-cement composite separators to simultaneously meet the requirements of electrode isolation， ion transport， and mechanical support. Related studies have been preliminarily validated in scenarios such as wall-integrated energy storage， LED power supply， pavement wireless charging， and structural health monitoring. However， most of the existing results remain at the stage of small-sized specimens or laboratory-scale devices. The key limitations of concrete-based energy storage batteries are as follows. Conductive phases and pore structures are beneficial for electrochemical performance but may compromise matrix compactness and mechanical strength. The durability of metal components in highly alkaline and moist environments remains insufficient. The energy density， cycling stability， and engineering-scale consistency of the devices are still insufficient to meet long-term service requirements. Future research should focus on alkali-resistant conductive frameworks， polymer-cement composite electrolytes， functional aggregates derived from industrial solid waste， gradient pore design， and directional forming by 3D printing. Long-term testing methods for service environments should also be established. By rationally distinguishing energy storage functional zones from load-bearing functional zones， the engineering applicability of such materials in building components and intelligent infrastructure can be gradually enhanced.

Research on correlation between SWHE performance and geometric parameters driven by working fluid physical properties

WANG Zixuan, LU Yuanwei, YANG Han, WU Yuting

2026, 48(6): 34-45. doi:10.3969/j.issn.2097-0706.2026.06.003

Asbtract ( 32 )

HTML ( 2)

PDF (1934KB) ( 11 )

Figures and Tables | References | Related Articles | Metrics

Spiral-wound tube heat exchangers （SWHE） hold significant application potential in the steam-molten salt heat exchange process within deep peak shaving systems for coal-fired power units. Existing research has primarily focused on optimizing SWHE geometric structures， leaving a research gap regarding the regulatory effects of working fluid thermophysical properties on SWHE performance. A multi-objective optimization framework was established by integrating a SWHE design calculation model with a non-dominated sorting genetic algorithm. The framework targeted comprehensive performance evaluation criteria for both hot and cold sides， average heat transfer coefficient， shell outer diameter， and total entropy generation number. Optimization design research was conducted for five mixed molten salts： solar salt， Hitec， Hitec XL， quaternary nitrate， and ternary nitrate. The results indicated that working fluid thermophysical properties significantly influenced the correlation between SWHE geometric parameters and performance. For instance， when high-viscosity molten salts （such as Hitec XL） served as working fluids， the winding angle of the SWHE exhibited a strong positive correlation with the overall heat transfer coefficient. Furthermore， increasing the tube diameter could enhance the heat transfer coefficient. This behavior differs significantly from SWHEs employing other molten salts as working fluids. Meanwhile， the correlation between the spiral angle of SWHEs using high-thermal-conductivity molten salts （such as quaternary nitrate） as working fluids and the entropy generation number showed characteristics opposite to those observed with other molten salts as working fluids. Finally， through comprehensive decision-making based on heat transfer intensity per unit volume and entropy generation number， four recommended solutions were selected from the Pareto solution set obtained by multi-objective optimization. Solution 1 exhibited optimal compactness （heat transfer area： 984.96 m²， construction cost： 5.838 million yuan）， but had higher operating costs （1.1531 million yuan/year）. Despite its larger heat transfer area （3 904.88 m²） and higher construction cost （12.161 million yuan）， Solution 4 achieves a 51.5% cut in annual operating cost （559 300 yuan/year） compared with Solution 1 due to its low entropy generation number. The results indicate that the thermophysical properties of mixed molten salts correlate with the performance and geometric parameters of SWHE， which lays a theoretical foundation and offers practical solutions for molten salt formulation screening and SWHE engineering design.

Performance analysis of tower-type solar thermal power plants based on multi-working fluid Brayton cycles

ZHANG Yue, ZHAI Rongrong, LI Jingwei, PAN Wenxin, CHEN Yong'an

2026, 48(6): 46-56. doi:10.3969/j.issn.2097-0706.2026.06.004

Asbtract ( 32 )

HTML ( 3)

PDF (1992KB) ( 15 )

Figures and Tables | References | Related Articles | Metrics

To collaboratively optimize the structure and parameters of the Brayton cycle system in tower-type concentrating solar power plants， the effects of cycle configuration， operating parameters， and CO₂-based binary working fluids on the thermodynamic performance of a solar power tower coupled with a supercritical CO₂ Brayton cycle were investigated， aiming to identify suitable configurations and working fluids under different ambient-temperature conditions. A bi-level optimization framework combining a genetic algorithm with sequential quadratic programming was developed. The genetic algorithm searched cycle configurations and discrete variables， whereas sequential quadratic programming optimized continuous operating parameters，such as temperature and pressure. After validation against a published case， the method was applied to cycles with optional reheating， intercooling， and split-flow processes. Based on REFPROP 9.1， four groups comprising 40 CO₂-based binary mixtures were constructed using H₂S， He， butane， and krypton as additives. Their specific work and thermal efficiency were compared， and S-CO₂，S-CO₂-50% He， and S-CO₂-50% H₂S were selected for typical-day analyses under the meteorological conditions of Delingha. The proposed bi-level optimization effectively coordinated cycle configuration and parameter optimization. Compared with the reference case， the optimized cycle increased specific work by 24.6% and thermal efficiency by 2.12%， and the optimal configuration included reheating and intercooling without splitting flow. Comparisons of pure working fluids showed that， relative to S-CO₂， He and H₂S increased specific work by approximately 324.8% and 28.5%， respectively， whereas butane and krypton reduced it by 35.9% and 71.5%. The duration of high-specific-work operation was strongly affected by meteorological conditions and generally increased from the spring equinox to the winter solstice. During high-temperature periods， the specific work of S-CO₂-50%He reaches 286.1 kJ/kg， which was significantly higher than that of S-CO₂-50%H₂S （138.2 kJ/kg） and pure S-CO₂（119.4 kJ/kg）. However， under low-temperature conditions， the specific work of S-CO₂-50% He fell below that of S-CO₂， whereas S-CO₂-50% H₂S provided gains throughout the entire operating period. The genetic algorithm-sequential quadratic programming framework is effective for coupled optimization of cycle structure and operating parameters. Reheating and intercooling are beneficial for enhancing cycle performance， while flow splitting is unnecessary in the optimal design. S-CO₂-50% He is more suitable for high-temperature conditions requiring maximum specific work， whereas S-CO₂-50% H₂S offers more stable performance over a wider temperature range. Working-fluid selection should therefore comprehensively consider local meteorological conditions， off-design performance， and the duration of high-specific-work operation， rather than relying solely on design-point performance.

Optimization of solar-assisted air source heat pump dual-source system for wolfberry drying in Northwest China

WANG Yingchao, LIU Yasuo, GAO Jia, JIANG Jiading, YIN Shaowu, FAN Xiaochao

2026, 48(6): 57-67. doi:10.3969/j.issn.2097-0706.2026.06.005

Asbtract ( 30 )

HTML ( 1)

PDF (2098KB) ( 4 )

Figures and Tables | References | Related Articles | Metrics

To address the high energy consumption，heavy carbon emissions， and the instability and weather dependency of traditional solar drying technologies in Northwest China， an efficient and stable multi-energy complementary drying system has been developed. The system aimed to provide a clean drying technology suitable for regions in Northwest China with abundant solar resources. Taking wolfberry drying in Jinghe County，Xinjiang Uygur Autonomous Region，as the application scenario，a solar-assisted air source heat pump dual-source drying system was proposed and constructed. A dynamic simulation model was established on the TRNSYS platform. Combined with local meteorological data，the operational characteristics of the system under typical operating conditions were analyzed. A dual-mode operational strategy based on working-condition switching was proposed：solar energy provided heating independently on sunny days，while the heat pump supplied auxiliary heating on cloudy days or under insufficient solar irradiation conditions. Taking the system's annual cost as the optimization objective，key parameters including collector area，heat pump heating capacity，and collector tilt angle were optimized using the Genopt optimization algorithm. The system exhibited excellent performance under optimal parameter combinations. The results showed that after optimization，the system's annual cost decreased by 9%，the operational energy efficiency ratio improved to 3.4，and the initial investment was reduced by 11%. Additionally， the drying period for wolfberry was shortened from 18-22 h with traditional methods to 12 h， significantly enhancing drying efficiency. In terms of environmental benefits， the system achieved an 81.3% reduction in CO₂ emissions compared to the conventional drying method supported by coal. The dynamic synergy mechanism and optimized system parameters should follow the principle of "prioritizing solar thermal energy and taking heat pumps as supplementary heat sources". This strategy effectively addressed the intermittency of solar energy， reduced the operating costs， and lowered carbon emissions. The findings provide a reliable theoretical basis and a practically valuable technical scheme for the green upgrading of agricultural product drying equipment in the high irradiation regions of Northwest China.

Study on performance of a 150 ℃ high-temperature coupled heat pump for industrial waste heat recovery

SUN Jian, LIU Minhui, HU Yunrong, XUE Jianhao, HU Zhiwu, DU Xiaoze

2026, 48(6): 68-81. doi:10.3969/j.issn.2097-0706.2026.06.006

Asbtract ( 36 )

HTML ( 2)

PDF (2007KB) ( 8 )

Figures and Tables | References | Related Articles | Metrics

There is insufficient research on working fluid optimization， thermodynamic characteristics and economic performance analysis of existing coupled heat pumps providing 150 ℃ heat supply. Therefore， a 150 ℃ compression-absorption coupled high-temperature heat pump unit was proposed， to improve the utilization rate of low-temperature waste heat， lower the energy consumption in industrial high-temperature heat supply and decrease the operational costs of the unit. A system mathematical model was established based on steady-state thermodynamics， and pure working fluids on the high-pressure side and binary mixed working fluids on the low-pressure side were screened. The effects of evaporator-condenser temperature， heating temperature， waste heat outlet temperature， and compression ratio of the water vapor compressor on the thermodynamic performance of the unit were analyzed， and comparison of economic efficiency was conducted. The results showed that the optimal working fluid on the high-pressure side was trans-1-chloro-3，3，3-trifluoropropene， the optimal mixed working fluid on the low-pressure side was n-Pentane（R601）/cis-1，3，3，3-tetrafluoropropene， the optimal mole fraction of R601 was 0.69， and the coefficient of performance （COP） of the system was 5.16. When the evaporator-condenser temperature increased from 85 ℃ to 95 ℃， the COP decreased from 2.16 to 2.02， while the heating capacity increased from 739.29 kW to 761.26 kW. When the heating temperature increased from 140 ℃ to 160 ℃， the COP decreased from 2.22 to 1.97， while the heating capacity increased from 727.00 kW to 774.95 kW. When the waste heat outlet temperature increased from 40 ℃ to 50 ℃， the COP increased from 1.91 to 2.14， while the heating capacity decreased from 1 314.83 kW to 617.46 kW. When the compression ratio of the water vapor compressor increased from 1.20 to 1.70， the COP decreased from 2.14 to 2.06， the mass fraction of concentrated lithium bromide solution increased from 54.16% to 58.02%， and the circulation ratio decreased from 6.56 to 4.79. Under the same heating capacity， the hourly operating cost of the coupled heat pump system was reduced by 55.6% and 72.8% compared to gas boilers and electric boilers， respectively. The findings indicate that the coupled heat pump unit shows good thermodynamic performance and economic efficiency， and has promising application prospects in deep recovery of industrial medium- and low-temperature waste heat and substitution for high-temperature heat supply.

Simulation and optimal scheduling of integrated heat-electricity-gas energy systems considering network dynamic characteristics

WANG Jin, QIU Yong, ZHANG Ruifang, LIU Yuhui, SHAO Jintao

2026, 48(6): 82-91. doi:10.3969/j.issn.2097-0706.2026.06.007

Asbtract ( 41 )

HTML ( 2)

PDF (2394KB) ( 10 )

Figures and Tables | References | Related Articles | Metrics

In integrated energy systems （IES）， heat network transmission delay can readily cause supply-demand mismatch and energy efficiency loss， undermining system stability. To address this， a method capable of accurately characterizing network dynamic characteristics and effectively optimizing dispatch strategies was developed， to enhance both the economic viability and stability of IES. Initially， a multi-energy coupling model incorporating network dynamic characteristics was constructed based on the Modelica language， and the partial differential equations of the pipeline network and nodal algebraic equations were solved in a unified manner to accurately characterize the spatiotemporal coupling relationship of energy transmission. Subsequently， a two-stage optimization mechanism integrating "operational decision-making and simulation evaluation" was designed， where the dynamic model was used to optimize the day-ahead output schedule of heat sources， and a "thermal power imbalance rate" was introduced to quantify the impact of thermodynamic processes， thereby providing feedback correction for the scheduling strategy. Simulation was conducted based on an established thermal-electrical-gas IES model. The optimization results showed that， compared to the traditional static dispatch strategy （C-OS）， the proposed two-stage optimal dispatch mechanism （HTD-TSOS） significantly reduced the thermal power imbalance rate from 9.58% to 0.97%， effectively suppressing temperature fluctuations at the user end and markedly improving the quality of heat supply. Concurrently， the daily operational cost of the system decreased by approximately 10，400 yuan， yielding remarkable economic benefits. A comparative analysis on the dispatch results indicated that considering heat transmission delays had a profound impact on the output schedule of combined heat and power （CHP） units， whereas its effect on energy storage equipment was relatively minor. Ultimately， this method integrated IES optimal dispatch and network dynamic characteristic analysis into a unified framework， successfully overcoming the limitations of previous studies that treated these two aspects in isolation. The proposed HTD-TSOS significantly alleviated the supply-demand imbalance caused by heat transmission delay， effectively reducing system operational costs while enhancing users’ thermal comfort. This approach provided a highly practical and feasible solution for the optimal operation， efficient regulation， and scientific management of IES， offering valuable references for promoting the large-scale application of IES.

Construction and thermodynamic analysis of an IBC-based atmospheric-pressure SOFC-GT system

FAN Xiaochao, ZHOU Kai, SHI Ruijing, ZHANG Zhihao

2026, 48(6): 92-104. doi:10.3969/j.issn.2097-0706.2026.06.008

Asbtract ( 31 )

HTML ( 1)

PDF (2447KB) ( 6 )

Figures and Tables | References | Related Articles | Metrics

Traditional pressurized solid oxide fuel cell-gas turbine （SOFC-GT）hybrid power generation systems require high-pressure vessels and sophisticated high-temperature sealing structures， and the working conditions of atmospheric-pressure solid oxide fuel cells （SOFC） can hardly match those of conventional Brayton cycle， leading to low waste heat utilization rate and limited industrial application scenarios. To address the technical bottlenecks above， taking efficient recovery of high-temperature exhaust waste heat from SOFC under atmospheric pressure and simplification of system equipment configuration as the research objectives， an atmospheric-pressure SOFC-GT hybrid power generation system based on the inverted Brayton cycle （IBC） characterized by expansion prior to cooling and compression was constructed. The system consisted of three main parts： a fuel/air pretreatment process， an IBC waste heat recovery system， and a SOFC module. Thermodynamic equations for components including turbines， compressors， heat exchangers and afterburners were derived the electrochemical model of SOFC， and an evaluation system centered on total output power， thermal efficiency and exergy efficiency was constructed. The system simulation was completed using EBSILON software. According to the rated operating condition determined by temperature gradient， carbon deposition prevention steam-to-carbon ratio and compressor surge margin， the key parameter sensitivity analysis as well as system exergy balance calculation were carried out simultaneously. Thermodynamic analysis results based on EBSILON software showed that under the given operating conditions， the SOFC AC power generation efficiency reached 58.78%， the net output power of the IBC waste heat utilization system was 33.53 kW， the system's exergy efficiency reached 60.84%， and the total output efficiency reached 72.86%.The hybrid power generation system is demonstrated to have a lower equipment cost and operational difficulty without pressure vessels and complex sealing structures， and its power generation performance is significantly superior to that of the traditional atmospheric-pressure coupling configuration. Although various irreversible processes cause considerable exergy loss and there is still room for optimization in the system's exergy utilization， the total efficiency of 72.86% fully verifies the superior performance of the IBC-based SOFC-GT hybrid power generation system.

Typical daily performance analysis of a wind-photovoltaic-gas complementary integrated energy system

XU Juan, LI Chao, ZHAI Rongrong

2026, 48(6): 105-114. doi:10.3969/j.issn.2097-0706.2026.06.009

Asbtract ( 34 )

HTML ( 1)

PDF (1928KB) ( 21 )

Figures and Tables | References | Related Articles | Metrics

To address the lack of systematic time-of-use （TOU） operational strategies and unified quantitative evaluation frameworks in existing research on wind-solar-gas integrated energy systems （IES）， this study proposed an optimized operational strategy adaptable to seasonal load characteristics by constructing an IES model incorporating wind power， photovoltaics， and fuel cells. The strategy aimed to enhance the system's economic viability， environmental sustainability， and energy utilization efficiency. Initially， a mathematical IES model was developed using Matlab. A three-dimensional comprehensive performance evaluation system was established， encompassing indicators for thermal performance （energy consumption）， economic performance （operational costs）， and environmental performance （CO₂ emissions）. Subsequently， taking an industrial park in Gansu Province as the case study， typical days representing peak， transition， and off-peak seasons were selected to comparatively analyze the system performance under "electricity-following-heat" （EFH） and "heat-following-electricity" （HFE） operational modes. Furthermore， the impact of the cooling load allocation coefficient （β） on system energy consumption under different operational modes was thoroughly investigated. Simulation results indicated that the system's operational strategy exhibited significant seasonal dependence. During the peak and transition seasons， the EFH mode demonstrated superior performance over the HFE mode in terms of energy consumption， operational costs， and CO₂ emissions. During the peak season， the peak energy consumption under the EFH mode （114.7 MW） was substantially lower than that under the HFE mode （175.0 MW）， with the maximum CO₂ emissions reduced by approximately 38.6%. During the off-peak season， the system displayed distinct time-varying characteristics： the HFE mode performed better between 10：00 and 18：00 economically and energetically， whereas the EFH mode was more advantageous during the remaining periods. Additionally， parameter analysis revealed that under the EFH mode， system energy consumption decreased linearly and smoothly as β increased. Conversely， under the HFE mode， energy consumption generally rose with a larger β. The findings confirm that a single operational mode cannot accommodate the IES load variations over a whole year. Implementing a complementary operational strategy based on time segments is crucial for achieving optimal system performance. Specifically， the EFH mode should be applied continuously during the peak and transition seasons， while a TOU strategy should be adopted during the off-peak season. This strategy not only effectively reduces operational costs but also significantly curtails carbon emissions. Meanwhile， the EFH mode exhibits superior robustness against variations in the electric cooling load allocation coefficient， providing a theoretical basis for parameter setting and optimized dispatch in similar systems.

Table of Content