The Gasbag Phase-change Carbon Dioxide Energy Storage System leverages elastic gasbags to store carbon dioxide under varying geographical conditions.This approach utilizes the phase-change sensible heat effect to effi...The Gasbag Phase-change Carbon Dioxide Energy Storage System leverages elastic gasbags to store carbon dioxide under varying geographical conditions.This approach utilizes the phase-change sensible heat effect to efficiently manage energy storage and release.This technology requires lower pressure and temperature control,resulting in reduced energy consumption and improved efficiency.Additionally,it is less restricted by geographical factors to a certain extent,enabling the formation of a closed-loop system.This contributes to the development of new energy utilization systems.The article examines and compares two experimental energy storage projects employing elastic gasbags to maintain a constant pressure supply of carbon dioxide on the low-pressure side.It further details the precise calculation methods for system cycle efficiency and energy storage density while analyzing energy losses incurred during the storage and release phases.Finally,an economic analysis is conducted using specific data,demonstrating that optimizing temperature and pressure parameters at various nodes enhances overall system efficiency while reducing energy consumption.Furthermore,the study highlights the system's high sensitivity to grid electricity prices.This research is anticipated to contribute to the development of more efficient and reliable energy storage solutions for power systems,addressing the growing energy demands and sustainability challenges.展开更多
The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high ...The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high energy storage density,showing great potential toward addressing the energy storage problems associated with decentralized,intermittent,and unstable renewable energy sources.Notably,effective heat transfer within the SLPCM-LHTES is crucial for extending its application potential.Therefore,a comprehensive understanding of the heat transfer processes in SLPCM-LHTES from a theoretical perspective is necessary.In this review,we propose a three-stage heat transfer pathway in SLPCM-LHTES,including external heating,interfacial heat transfer,and intrinsic phase transition processes.From the perspective of this three-stage pathway,the theoretical basis of heat transfer processes and typical efficiency enhancement strategies in SLPCM-LHTES are summarized.Moreover,an overview of the typical applications of SLPCM-LHTES in various fields,such as building energy efficiency,textiles and garments,and battery thermal management,is presented.Finally,the remaining challenges and possible avenues of research in this burgeoning field will also be discussed.展开更多
Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was desi...Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was designed for cold storage applications.The optimal number of PCM plates was determined through numerical simulations to meet the required cold storage temperature and control time.Additionally,the air temperature field,flow field,and melting characteristics of the PCMplates during the cooling release process were analyzed.The effects of plate positioning and thickness on the cooling release performance were further investigated.The results indicated that when 64PCMplateswere used,the duration formaintaining temperatures below−18℃increased from0.6 h to approximately 16.94 h.During the cooling release process,the temperature field in the cold storage exhibited stratification,and the melting of the PCM plates was non-uniform.Placing the PCM plates at the top or within the interlayers without cargo above proved more effective,with their cooling release power being approximately twice that of the PCM plates placed in the interlayers with cargo above.Furthermore,reducing the thickness of the PCMplates from15 to 7.5mmresulted in a 3.6-h increase in the time below−18℃and a 4.5-h reduction in the time required to reach 80%liquid phase fraction.展开更多
Deep mining is an inevitable tendency in the development of coal industry. There are many heat damage problems with the increase of mining depth. The technology of using doublet wells, together with Heat Exchange Ma...Deep mining is an inevitable tendency in the development of coal industry. There are many heat damage problems with the increase of mining depth. The technology of using doublet wells, together with Heat Exchange Machine Systems （HEMSs）, to store cold energy is a key to solve the heat damage problems in deep mines. Based on the geological conditions, thermodynamic and hydraulic parameters of Jiahe Mine, the isotherms in the period of cold energy storage and refrigeration and the volumes of cold water within different temperature ranges of the cold energy storage well were numerically analyzed. The results show that 1） with the same pumped and injected water volumes, the lower the temperature of injected water is, the larger the volume.of cold water in the cold energy storage well is. With the larger volume, the effect of cold energy storage is better. 2） the larger the volumes of pumped and reinjected water frigeration is better. And 3） without disturbance, the volume and temperature of cold water in the cold energy storage well can keep unchanged or have only a little change for a long time. Therefore the technology of doublet wells for cold energy storage is feasible and the cold energy storage aquifers can meet the requirement of the technology.展开更多
Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a ...Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).展开更多
Recently, although renewable energy has a great development, primary source is still thermal power generation, which uses fossil fuel as the energy source. Supply and demand of fossil fuel are essential for social and...Recently, although renewable energy has a great development, primary source is still thermal power generation, which uses fossil fuel as the energy source. Supply and demand of fossil fuel are essential for social and economy development. However, development pattern that excessively relies on the natural source is impossible to provide a sustainable development way for us. As a result, we should combine renewable energy with new energy technology as the aim of economy. It means that it is urgent to exploit new energy. Meanwhile, the ratio of energy waste cannot be ignored. How to decrease energy waste is also significant. Construction sector costs a lot of energy, which is mainly used for heating and refrigeration. In the new energy generation technology, thermal energy can be transformed to electricity with combination of BIPV and thermal energy storage technology. Photovoltaic generation has a great progress in the building construction. As a result, the thermal energy storage technology becomes the key link in the production chain. In this paper, feasibility of applying phase-change material (PCM) in the thermal energy storage will be analyzed. And analysis results are provided with a relative mathematical model.展开更多
This paper proposes a theoretical study of a cold storage system in a CO2 （carbon dioxide） MT （medium temperature） plant for supermarkets application. The aim of this plant strategy is that in the daily hours the ...This paper proposes a theoretical study of a cold storage system in a CO2 （carbon dioxide） MT （medium temperature） plant for supermarkets application. The aim of this plant strategy is that in the daily hours the storage can export heat form the refrigerant outcoming the gas cooler/condenser whereas during the nightly hours it can be maintained cooled by this latter before its incoming into the evaporator. Besides, the storage can be used for reducing the energy peak consumption, permitting to size the plant on a lower energy target, and it can influence the choice of the optimisation logic of the plant controller, in this work a model for a MT CO2 transcritical/subcritical cycle, able to manage the transient due to the changes of loads and external conditions, is proposed to take into account the evolution with time in a fixed time step. A parametrical analysis has been conduced for understanding the optimal design of the plant. A seasonal analysis is considered too, for understanding the cold storage benefits in different periods of year.展开更多
As the installed capacity of renewable energy such as wind and solar power continues to increase,energy storage technology is becoming increasingly crucial.It could effectively balance power demand and supply,enhance ...As the installed capacity of renewable energy such as wind and solar power continues to increase,energy storage technology is becoming increasingly crucial.It could effectively balance power demand and supply,enhance allocation flexibility,and improve power quality.Among various energy storage technologies,liquid CO_(2)energy storage(LCES)stands out as one of the most promising options due to its advantages such as high round-trip efficiency(RTE),high energy storage density(ESD),safety,stability,and longevity.Within the system,the cold and heat storage units play a critical role in determining the overall performance of the system and are particularly important among its various components.In this paper,a novel LCES system is proposed and the heat transfer characteristics are analyzed in detail.Then,the impact of key parameters on the liquefaction ratio and RTE is discussed.The results indicate that the RTE,ESD,and exergy efficiency of the system are 56.12%,29.46 kWh/m^(3),and 93.73%under specified design conditions,respectively.During the gas-liquid phase change process of carbon dioxide or when it is in a supercritical state,the related heat transfer processes become more complex,leading to increased energy loss.The analysis of key parameters of the Linde-Hampson liquefaction unit reveals that as the liquefaction temperature decreases,both the liquefaction ratio and RTE increase.While the liquefaction pressure has a minimal impact on the liquefaction ratio,it significantly affects RTE,with an optimal liquefaction pressure identified.展开更多
Cold sintering as a new technology for the fabrication of ceramic composites could overcome the shortcomings of traditional high temperature sintering approach and achieve dense structure in the composite at a relativ...Cold sintering as a new technology for the fabrication of ceramic composites could overcome the shortcomings of traditional high temperature sintering approach and achieve dense structure in the composite at a relatively low temperature(<200℃).In this work,a shape stabilization phase change composite is fabricated and investigated by dint of such new fabrication approach,in which a mixed nitrate salt of NaNO_(3)-KNO_(3) is used as phase change material and magnesia powder is acted as structure skeleton.Using of deionized water as sintering additive,the effects of sintering agent content,sintering temperature,uniaxial pressure and time on the composite microstructure characteristics and macroscopic properties are evaluated.The results show that the liquid salt could be effectively accommodated in the magnesia skeleton,forming a dense and stable structure in the composite.There is existence of optimal cold sintering parameters at which a benign combination of mechanical strength and thermal cycling performance could be attained in the composite.Under the sintering temperature of150℃,duration time of 8 min,uniaxial pressure of 150 MPa,and water mass content of 7%,the fabricated composite exhibits a heat storage density of 610 kJ/kg at its potential utilization temperature range of30℃-580℃ and a compressive strength over 240 MPa with a dense density higher than 98%,demonstrating that it can be a viable alternative used in thermal energy storage domains.展开更多
In this study,the influence of the phase-change cooling storage system on integrating and controlling of the combined cooling,heating,and power system was analyzed through experiments and computational fluid dynamics ...In this study,the influence of the phase-change cooling storage system on integrating and controlling of the combined cooling,heating,and power system was analyzed through experiments and computational fluid dynamics simulations.The model of three-dimensional phase change material plate and cold storage tank was established and verified.The phase change material selected in this study is a eutectic salt with a phase change temperature of 8℃.The thermodynamic performance of the cold storage tank filled with phase change material plates was calculated,and the energy storage and release efficiency of the phase-change cooling storage system was analyzed.The results indicate that the phase change process correlates positively with the heat transfer fluid flow rate.The heat transfer fluid flow rates of 1.2 m^(3)/h,1.6 m^(3)/h,and 2.0 m^(3)/h all allow the phase change material within the encapsulation module to completely solidify within 8 hours;the flow rate required for melting is not less than 2.0 m^(3)/h,and the highest energy storage efficiency is up to 72%.Considering the thermodynamic performance of the phase-change cooling storage system,it is recommended to use a heat transfer fluid flow rate of 1.6 m^(3)/h for the cooling charge process and 2.0 m^(3)/h for the cooling release process.展开更多
海上风电接入海上油田群电网是实现“双碳”目标的重要途径之一。然而,随着海上风电的高比例接入,以新能源为主导的海上独立电网存在电力电量平衡及频率稳定等问题,因此,该文提出一种以新能源为主导的海上独立电网储能优化配置方法。首...海上风电接入海上油田群电网是实现“双碳”目标的重要途径之一。然而,随着海上风电的高比例接入,以新能源为主导的海上独立电网存在电力电量平衡及频率稳定等问题,因此,该文提出一种以新能源为主导的海上独立电网储能优化配置方法。首先,考虑电池储能系统(battery energy storage system,BESS)参与一次调频和紧急频率支援,构建BESS频率稳定性约束条件。其次,构建以经济性为目标的储能双层优化配置模型。其中,外层模型引入荷电状态(state of charge,SOC)自适应调整和频率稳定约束,内层模型考虑冷备机组启停工况。然后,采用CPLEX求解器和樽海鞘算法求解双层模型得到储能优化配置结果。最后,以一海上油气田群独立电网为例,验证了所提理论的正确性和有效性。结果表明,所提方法可以提升海上独立电网的频率稳定性、经济性、风电消纳能力,减少了冷备机组启停次数。展开更多
A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperatur...A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperature 300℃ under uniaxial pressure in the presence of small amount o f transient liquid.The fabricated composite achieved as high as 98.65% of the theoretical density.The NaCl-Al2O3 composite also retained the chloride salt without leakage after 30 heating-cooling cycles between 750℃-850℃ together with a holding period o f 24h at 850℃.X-ray diffraction measurements indicated congruent solubility o f the alumina in chloride salt,excellent compatibility o f NaCl with Al2O3,and chemical stability at high temperature.Structural analysis by scanning electron microscope also showed limited grain growth,high density,uniform NaCl distribution and clear faceted composite structure without inter-diffusion.The latent heat storage density o f 252.5J/g was obtained from simultaneous thermal analysis.Fracture strength test showed high sintered strength around 5 GPa after 50 min.The composite was found to have fair mass losses due to volatilization.Overall,cold sintering process has the potential to be an efficient,safe and cost-effective strategy for the fabrication of high temperature thermal energy storage materials.展开更多
In this study,experimental and numerical investigations were conducted on a tube-fin heat-exchanger latent-heat cold energy storage unit.The fin side of the heat exchanger was filled with water as the energy storage m...In this study,experimental and numerical investigations were conducted on a tube-fin heat-exchanger latent-heat cold energy storage unit.The fin side of the heat exchanger was filled with water as the energy storage medium,and modified expanded graphite(MEG)was employed to improve the thermal characteristics of water.The water contact angle of the expanded graphite decreased from 106.31°to 0°,and the hydrophilicity and the absorption rate of water significantly improved after the modification.Moreover,the experimental analyses of the charge/discharge process showed that the cooling capacity of the system filled with 90 wt.%water/MEG was 80.8%of that of pure water,whereas its cooling time was only 69.7%of that of pure water.The average power increased by 15.9%compared with that of water.The system filled with 90 wt.%water/MEG completed two energy charging and discharging cycles,whereas the system filled with water completed only 1.5 cycles within 15000 s.Furthermore,the effects of the flow rate and inlet temperature of the heat transfer fluid on the charging process were explored.Finally,a numerical model was built and validated to investigate the phase change behavior and the effect of the structure size on the performance of the system.The heat-exchanger fin spacing had no significant effect on the cold energy storage unit,whereas the vertical spacing of the tube pass had the highest effect.It can be concluded that the heat exchanger combined with high-thermal-conductivity water/MEG exhibits better energy storage capacity and working power,showing a wide application prospect in the field of cold energy storage.展开更多
This paper aims to explore an efficient, cost-effective, and water-saving seasonal cold energy storage technique based on borehole heat exchangers to cool the condenser water in a 10 MW solar thermal power plant. The ...This paper aims to explore an efficient, cost-effective, and water-saving seasonal cold energy storage technique based on borehole heat exchangers to cool the condenser water in a 10 MW solar thermal power plant. The proposed seasonal cooling mechanism is designed for the areas under typical weather conditions to utilize the low ambient temperature during the winter season and to store cold energy. The main objective of this paper is to utilize the storage unit in the peak summer months to cool the condenser water and to replace the dry cooling system. Using the simulation platform transient system simulation program (TRNSYS), the borehole thermal energy storage (BTES) system model has been developed and the dynamic capacity of the system in the charging and discharging mode of cold energy for one-year operation is studied. The typical meteorological year (TMY) data of Dunhuang, Gansu province, in north-western China, is utilized to determine the lowest ambient temperature and operation time of the system to store cold energy. The proposed seasonal cooling system is capable of enhancing the efficiency of a solar thermal power plant up to 1.54% and 2.74% in comparison with the water-cooled condenser system and air-cooled condenser system respectively. The techno-economic assessment of the proposed technique also supports its integration with the condenser unit in the solar thermal power plant. This technique has also a great potential to save the water in desert areas.展开更多
Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage f...Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage free,no encapsulation,negligible volume variation,as well as superior energy storage properties such as high thermal conductivity(compared with ice and paraffin)and volumetric energy density,making them excellent thermal energy storage materials.Considering these characteristics,the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle.The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2°C at 9.85 s,which is reduced by 9.8°C,and the energy storage efficiency of the device is 66%.The influence of initial temperature,elastocaloric materials,and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed.Since SMAs are both solid-state refrigerants and thermal energy storage materials,hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.展开更多
The growing interest in energy conservation has inspired companies to seek alternatives to highly polluting fuel electricity generation. This study designed an optimised solar wind power generation system to fulfil th...The growing interest in energy conservation has inspired companies to seek alternatives to highly polluting fuel electricity generation. This study designed an optimised solar wind power generation system to fulfil the energy requirement of a cold chain logistics centre. This study first conducted a thorough analysis of the clarity indicators and daily temperature positions of the cold chain logistics centre, determined the average daily electricity demand, and proposed an effective design scheme. The energy simulation software, RETScreen 8.0, was used to determine the scale of solar photovoltaic and wind power projects that meet the expected energy needs of the cold chain logistics centre. The results indicated that the estimated annual total energy demand was 833689.2 kWh. The annual power generation of 6 kW from solar photovoltaic projects and 150 kW from wind power projects was found to be enough to meet the expected electricity demand. Solar photovoltaic power generation and wind power generation account for 2.44% and 97.56%, respectively. The hybrid energy system achieved a 96.6% reduction in carbon emissions and provides a reasonable payback period of 6.1 years and an electricity generation of 904368.674 kWh per year. The feasibility of the project and the calculated period of investment return are very reasonable. Therefore, this hybrid renewable energy system provides reliable power by combining energy sources.展开更多
基金funded by the Natural Science Foundation of Heilongjiang Province,China(Grant No.PL2024E027)。
文摘The Gasbag Phase-change Carbon Dioxide Energy Storage System leverages elastic gasbags to store carbon dioxide under varying geographical conditions.This approach utilizes the phase-change sensible heat effect to efficiently manage energy storage and release.This technology requires lower pressure and temperature control,resulting in reduced energy consumption and improved efficiency.Additionally,it is less restricted by geographical factors to a certain extent,enabling the formation of a closed-loop system.This contributes to the development of new energy utilization systems.The article examines and compares two experimental energy storage projects employing elastic gasbags to maintain a constant pressure supply of carbon dioxide on the low-pressure side.It further details the precise calculation methods for system cycle efficiency and energy storage density while analyzing energy losses incurred during the storage and release phases.Finally,an economic analysis is conducted using specific data,demonstrating that optimizing temperature and pressure parameters at various nodes enhances overall system efficiency while reducing energy consumption.Furthermore,the study highlights the system's high sensitivity to grid electricity prices.This research is anticipated to contribute to the development of more efficient and reliable energy storage solutions for power systems,addressing the growing energy demands and sustainability challenges.
基金financial support was provided by the National Natural Science Foundation of China(Nos.52476146,52006008,and 52471219)the Guangdong Basic and Applied Basic Research Foundation(2023A1515140059 and 2025A1515011255)+2 种基金the Peking University Third Hospital Haidian transformation project(HDCXZHKC2023210)the National Foreign Expert Individual Human Project(Category H,No.H20240116)the State Key Laboratory of New Ceramic Materials Tsinghua University(No.KFZD202402).
文摘The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high energy storage density,showing great potential toward addressing the energy storage problems associated with decentralized,intermittent,and unstable renewable energy sources.Notably,effective heat transfer within the SLPCM-LHTES is crucial for extending its application potential.Therefore,a comprehensive understanding of the heat transfer processes in SLPCM-LHTES from a theoretical perspective is necessary.In this review,we propose a three-stage heat transfer pathway in SLPCM-LHTES,including external heating,interfacial heat transfer,and intrinsic phase transition processes.From the perspective of this three-stage pathway,the theoretical basis of heat transfer processes and typical efficiency enhancement strategies in SLPCM-LHTES are summarized.Moreover,an overview of the typical applications of SLPCM-LHTES in various fields,such as building energy efficiency,textiles and garments,and battery thermal management,is presented.Finally,the remaining challenges and possible avenues of research in this burgeoning field will also be discussed.
基金supported by National Natural Science Foundation of China(Nos.51806092,52201410)Non-Carbon Energy Conversion and Utilization Institute under the Shanghai Class IV Peak Disciplinary Development Program,High-End Foreign Experts Recruitment Plan of China(G2022013028L).
文摘Phase Change Material(PCM)-based cold energy storage system(CESS)can effectively utilize the peak and valley power resources to reduce the excessive dependence on the power grid.In this study,a PCM-based CESS was designed for cold storage applications.The optimal number of PCM plates was determined through numerical simulations to meet the required cold storage temperature and control time.Additionally,the air temperature field,flow field,and melting characteristics of the PCMplates during the cooling release process were analyzed.The effects of plate positioning and thickness on the cooling release performance were further investigated.The results indicated that when 64PCMplateswere used,the duration formaintaining temperatures below−18℃increased from0.6 h to approximately 16.94 h.During the cooling release process,the temperature field in the cold storage exhibited stratification,and the melting of the PCM plates was non-uniform.Placing the PCM plates at the top or within the interlayers without cargo above proved more effective,with their cooling release power being approximately twice that of the PCM plates placed in the interlayers with cargo above.Furthermore,reducing the thickness of the PCMplates from15 to 7.5mmresulted in a 3.6-h increase in the time below−18℃and a 4.5-h reduction in the time required to reach 80%liquid phase fraction.
基金Project 50490270 supported by Key Project of National Natural Science Foundation of China
文摘Deep mining is an inevitable tendency in the development of coal industry. There are many heat damage problems with the increase of mining depth. The technology of using doublet wells, together with Heat Exchange Machine Systems （HEMSs）, to store cold energy is a key to solve the heat damage problems in deep mines. Based on the geological conditions, thermodynamic and hydraulic parameters of Jiahe Mine, the isotherms in the period of cold energy storage and refrigeration and the volumes of cold water within different temperature ranges of the cold energy storage well were numerically analyzed. The results show that 1） with the same pumped and injected water volumes, the lower the temperature of injected water is, the larger the volume.of cold water in the cold energy storage well is. With the larger volume, the effect of cold energy storage is better. 2） the larger the volumes of pumped and reinjected water frigeration is better. And 3） without disturbance, the volume and temperature of cold water in the cold energy storage well can keep unchanged or have only a little change for a long time. Therefore the technology of doublet wells for cold energy storage is feasible and the cold energy storage aquifers can meet the requirement of the technology.
基金Supported by the National Natural Science Foundation of China(21476065)the China National Tobacco Corporation
文摘Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).
文摘Recently, although renewable energy has a great development, primary source is still thermal power generation, which uses fossil fuel as the energy source. Supply and demand of fossil fuel are essential for social and economy development. However, development pattern that excessively relies on the natural source is impossible to provide a sustainable development way for us. As a result, we should combine renewable energy with new energy technology as the aim of economy. It means that it is urgent to exploit new energy. Meanwhile, the ratio of energy waste cannot be ignored. How to decrease energy waste is also significant. Construction sector costs a lot of energy, which is mainly used for heating and refrigeration. In the new energy generation technology, thermal energy can be transformed to electricity with combination of BIPV and thermal energy storage technology. Photovoltaic generation has a great progress in the building construction. As a result, the thermal energy storage technology becomes the key link in the production chain. In this paper, feasibility of applying phase-change material (PCM) in the thermal energy storage will be analyzed. And analysis results are provided with a relative mathematical model.
文摘This paper proposes a theoretical study of a cold storage system in a CO2 （carbon dioxide） MT （medium temperature） plant for supermarkets application. The aim of this plant strategy is that in the daily hours the storage can export heat form the refrigerant outcoming the gas cooler/condenser whereas during the nightly hours it can be maintained cooled by this latter before its incoming into the evaporator. Besides, the storage can be used for reducing the energy peak consumption, permitting to size the plant on a lower energy target, and it can influence the choice of the optimisation logic of the plant controller, in this work a model for a MT CO2 transcritical/subcritical cycle, able to manage the transient due to the changes of loads and external conditions, is proposed to take into account the evolution with time in a fixed time step. A parametrical analysis has been conduced for understanding the optimal design of the plant. A seasonal analysis is considered too, for understanding the cold storage benefits in different periods of year.
基金supported by the National Natural Science Foundation of China(Grant Nos.52206032 and 21978308)Special Fund for Central Guiding Local Science and Technology Development,China(ZYYD2022B11&2022ZY0048).
文摘As the installed capacity of renewable energy such as wind and solar power continues to increase,energy storage technology is becoming increasingly crucial.It could effectively balance power demand and supply,enhance allocation flexibility,and improve power quality.Among various energy storage technologies,liquid CO_(2)energy storage(LCES)stands out as one of the most promising options due to its advantages such as high round-trip efficiency(RTE),high energy storage density(ESD),safety,stability,and longevity.Within the system,the cold and heat storage units play a critical role in determining the overall performance of the system and are particularly important among its various components.In this paper,a novel LCES system is proposed and the heat transfer characteristics are analyzed in detail.Then,the impact of key parameters on the liquefaction ratio and RTE is discussed.The results indicate that the RTE,ESD,and exergy efficiency of the system are 56.12%,29.46 kWh/m^(3),and 93.73%under specified design conditions,respectively.During the gas-liquid phase change process of carbon dioxide or when it is in a supercritical state,the related heat transfer processes become more complex,leading to increased energy loss.The analysis of key parameters of the Linde-Hampson liquefaction unit reveals that as the liquefaction temperature decreases,both the liquefaction ratio and RTE increase.While the liquefaction pressure has a minimal impact on the liquefaction ratio,it significantly affects RTE,with an optimal liquefaction pressure identified.
基金supported by the National Key Research and Development Program of China (2023YFB2406500)National Natural Science Foundation of China (52406214)。
文摘Cold sintering as a new technology for the fabrication of ceramic composites could overcome the shortcomings of traditional high temperature sintering approach and achieve dense structure in the composite at a relatively low temperature(<200℃).In this work,a shape stabilization phase change composite is fabricated and investigated by dint of such new fabrication approach,in which a mixed nitrate salt of NaNO_(3)-KNO_(3) is used as phase change material and magnesia powder is acted as structure skeleton.Using of deionized water as sintering additive,the effects of sintering agent content,sintering temperature,uniaxial pressure and time on the composite microstructure characteristics and macroscopic properties are evaluated.The results show that the liquid salt could be effectively accommodated in the magnesia skeleton,forming a dense and stable structure in the composite.There is existence of optimal cold sintering parameters at which a benign combination of mechanical strength and thermal cycling performance could be attained in the composite.Under the sintering temperature of150℃,duration time of 8 min,uniaxial pressure of 150 MPa,and water mass content of 7%,the fabricated composite exhibits a heat storage density of 610 kJ/kg at its potential utilization temperature range of30℃-580℃ and a compressive strength over 240 MPa with a dense density higher than 98%,demonstrating that it can be a viable alternative used in thermal energy storage domains.
基金supported by the National Key Research and Development Program of China (Grant No.2023YFB4204000)National Key Research and Development Program of China (Grant No.2024YFB4206500)。
文摘In this study,the influence of the phase-change cooling storage system on integrating and controlling of the combined cooling,heating,and power system was analyzed through experiments and computational fluid dynamics simulations.The model of three-dimensional phase change material plate and cold storage tank was established and verified.The phase change material selected in this study is a eutectic salt with a phase change temperature of 8℃.The thermodynamic performance of the cold storage tank filled with phase change material plates was calculated,and the energy storage and release efficiency of the phase-change cooling storage system was analyzed.The results indicate that the phase change process correlates positively with the heat transfer fluid flow rate.The heat transfer fluid flow rates of 1.2 m^(3)/h,1.6 m^(3)/h,and 2.0 m^(3)/h all allow the phase change material within the encapsulation module to completely solidify within 8 hours;the flow rate required for melting is not less than 2.0 m^(3)/h,and the highest energy storage efficiency is up to 72%.Considering the thermodynamic performance of the phase-change cooling storage system,it is recommended to use a heat transfer fluid flow rate of 1.6 m^(3)/h for the cooling charge process and 2.0 m^(3)/h for the cooling release process.
文摘海上风电接入海上油田群电网是实现“双碳”目标的重要途径之一。然而,随着海上风电的高比例接入,以新能源为主导的海上独立电网存在电力电量平衡及频率稳定等问题,因此,该文提出一种以新能源为主导的海上独立电网储能优化配置方法。首先,考虑电池储能系统(battery energy storage system,BESS)参与一次调频和紧急频率支援,构建BESS频率稳定性约束条件。其次,构建以经济性为目标的储能双层优化配置模型。其中,外层模型引入荷电状态(state of charge,SOC)自适应调整和频率稳定约束,内层模型考虑冷备机组启停工况。然后,采用CPLEX求解器和樽海鞘算法求解双层模型得到储能优化配置结果。最后,以一海上油气田群独立电网为例,验证了所提理论的正确性和有效性。结果表明,所提方法可以提升海上独立电网的频率稳定性、经济性、风电消纳能力,减少了冷备机组启停次数。
文摘A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperature 300℃ under uniaxial pressure in the presence of small amount o f transient liquid.The fabricated composite achieved as high as 98.65% of the theoretical density.The NaCl-Al2O3 composite also retained the chloride salt without leakage after 30 heating-cooling cycles between 750℃-850℃ together with a holding period o f 24h at 850℃.X-ray diffraction measurements indicated congruent solubility o f the alumina in chloride salt,excellent compatibility o f NaCl with Al2O3,and chemical stability at high temperature.Structural analysis by scanning electron microscope also showed limited grain growth,high density,uniform NaCl distribution and clear faceted composite structure without inter-diffusion.The latent heat storage density o f 252.5J/g was obtained from simultaneous thermal analysis.Fracture strength test showed high sintered strength around 5 GPa after 50 min.The composite was found to have fair mass losses due to volatilization.Overall,cold sintering process has the potential to be an efficient,safe and cost-effective strategy for the fabrication of high temperature thermal energy storage materials.
基金National Key R&D Program of China(Grant No.:2020YFA0210704).
文摘In this study,experimental and numerical investigations were conducted on a tube-fin heat-exchanger latent-heat cold energy storage unit.The fin side of the heat exchanger was filled with water as the energy storage medium,and modified expanded graphite(MEG)was employed to improve the thermal characteristics of water.The water contact angle of the expanded graphite decreased from 106.31°to 0°,and the hydrophilicity and the absorption rate of water significantly improved after the modification.Moreover,the experimental analyses of the charge/discharge process showed that the cooling capacity of the system filled with 90 wt.%water/MEG was 80.8%of that of pure water,whereas its cooling time was only 69.7%of that of pure water.The average power increased by 15.9%compared with that of water.The system filled with 90 wt.%water/MEG completed two energy charging and discharging cycles,whereas the system filled with water completed only 1.5 cycles within 15000 s.Furthermore,the effects of the flow rate and inlet temperature of the heat transfer fluid on the charging process were explored.Finally,a numerical model was built and validated to investigate the phase change behavior and the effect of the structure size on the performance of the system.The heat-exchanger fin spacing had no significant effect on the cold energy storage unit,whereas the vertical spacing of the tube pass had the highest effect.It can be concluded that the heat exchanger combined with high-thermal-conductivity water/MEG exhibits better energy storage capacity and working power,showing a wide application prospect in the field of cold energy storage.
基金This work was supported by the Key Project of the National Natural Science Foundation of China for International Academic Exchanges(Grant No.51561145012)and the Gree Electric Appliances,Inc.Zhuhai,Guangdong Province.
文摘This paper aims to explore an efficient, cost-effective, and water-saving seasonal cold energy storage technique based on borehole heat exchangers to cool the condenser water in a 10 MW solar thermal power plant. The proposed seasonal cooling mechanism is designed for the areas under typical weather conditions to utilize the low ambient temperature during the winter season and to store cold energy. The main objective of this paper is to utilize the storage unit in the peak summer months to cool the condenser water and to replace the dry cooling system. Using the simulation platform transient system simulation program (TRNSYS), the borehole thermal energy storage (BTES) system model has been developed and the dynamic capacity of the system in the charging and discharging mode of cold energy for one-year operation is studied. The typical meteorological year (TMY) data of Dunhuang, Gansu province, in north-western China, is utilized to determine the lowest ambient temperature and operation time of the system to store cold energy. The proposed seasonal cooling system is capable of enhancing the efficiency of a solar thermal power plant up to 1.54% and 2.74% in comparison with the water-cooled condenser system and air-cooled condenser system respectively. The techno-economic assessment of the proposed technique also supports its integration with the condenser unit in the solar thermal power plant. This technique has also a great potential to save the water in desert areas.
基金supported by the National Natural Science Foundation of China(Grant No.51976149)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(Grant No.2019QNRC001).
文摘Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage free,no encapsulation,negligible volume variation,as well as superior energy storage properties such as high thermal conductivity(compared with ice and paraffin)and volumetric energy density,making them excellent thermal energy storage materials.Considering these characteristics,the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle.The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2°C at 9.85 s,which is reduced by 9.8°C,and the energy storage efficiency of the device is 66%.The influence of initial temperature,elastocaloric materials,and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed.Since SMAs are both solid-state refrigerants and thermal energy storage materials,hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.
文摘The growing interest in energy conservation has inspired companies to seek alternatives to highly polluting fuel electricity generation. This study designed an optimised solar wind power generation system to fulfil the energy requirement of a cold chain logistics centre. This study first conducted a thorough analysis of the clarity indicators and daily temperature positions of the cold chain logistics centre, determined the average daily electricity demand, and proposed an effective design scheme. The energy simulation software, RETScreen 8.0, was used to determine the scale of solar photovoltaic and wind power projects that meet the expected energy needs of the cold chain logistics centre. The results indicated that the estimated annual total energy demand was 833689.2 kWh. The annual power generation of 6 kW from solar photovoltaic projects and 150 kW from wind power projects was found to be enough to meet the expected electricity demand. Solar photovoltaic power generation and wind power generation account for 2.44% and 97.56%, respectively. The hybrid energy system achieved a 96.6% reduction in carbon emissions and provides a reasonable payback period of 6.1 years and an electricity generation of 904368.674 kWh per year. The feasibility of the project and the calculated period of investment return are very reasonable. Therefore, this hybrid renewable energy system provides reliable power by combining energy sources.
