Direct absorption solar collectors use nanofluids to absorb and convert solar radiation. Despite the limitations of the photothermal properties of these nanofluids within the absorption spectra range, modifying the su...Direct absorption solar collectors use nanofluids to absorb and convert solar radiation. Despite the limitations of the photothermal properties of these nanofluids within the absorption spectra range, modifying the surface structure of the nanoparticles can broaden their absorption spectrum, thereby significantly improving the solar thermal conversion efficiency. This paper utilizes the finite element method to investigate the influence of surface pits on the photothermal properties of plasmonic nanoparticles, considering both material composition and surface micro-nano structures. Based on the findings, a novel Ti N nanoparticle is proposed to enhance photothermal performance. This nanoparticle exhibits the lowest average reflectance(0.0145) in the 300–1100 nm wavelength range and the highest light absorption intensity across the solar spectrum, enabling highly efficient solar energy conversion. It not only reduces material costs but also effectively broadens the light absorption spectrum of spherical plasmonic nanoparticles. The distributions of the electric field, magnetic field, and energy field of the nanoparticles indicate that the combination of the “lightning rod” effect and surface plasmon resonance(SPR) significantly enhances both the electric and magnetic fields, thereby increasing the localized heating effect and improving the photothermal performance. Additionally, the number and size of the pits have a significant impact on the absorption efficiency(η_(abs)) of TiN nanoparticles. When the surface of the nanoparticles has 38 pits, η_(abs) can reach90%, with the minimum optical penetration depth(h) of the nanofluid being 7 mm and the minimum volume fraction(f_(v))being 6.95×10^(-6). This study demonstrates that nanoparticles with micro-nano structures have immense potential in solar thermal applications, particularly in the field of direct absorption solar collectors.展开更多
A unified theory of non-equilibrium radiation thermodynamics is always in search as it is meaningful for solar energy utilization.An exergy analysis of photo-thermal interaction process between the solar radiation ene...A unified theory of non-equilibrium radiation thermodynamics is always in search as it is meaningful for solar energy utilization.An exergy analysis of photo-thermal interaction process between the solar radiation energy and solar receiver is conducted in this paper.The non-equilibrium radiation thermodynamic system is described.The thermodynamic process of photo-thermal interaction between the solar radiation and solar receiver is introduced.Energy,exergy and entropy equations for the photo-thermal process are provided.Formulas for calculating the optimum receiving temperatures of the solar receiver under both non-concentration and solar concentration conditions are presented.A simple solar receiver is chosen as the calculation example to launch the exergy analysis under non-concentration condition.Furthermore,the effect analysis of solar concentration on the thermodynamic performance of the solar receiver for solar thermal utilization is carried out.The analysis results demonstrate that both the output exergy flux and efficiency of the solar receiver can be improved by increasing the solar concentration ratio during the solar thermal utilization process.The formulas and results provided in this paper may be used as a theoretical reference for the further studies of non-equilibrium radiation thermodynamic theory and solar thermal utilization.展开更多
Reducing CO2 emissions and restraining dependence on nuclear power generation are serious concerns in the prevention of global warming since the Great East Japan Earthquake. To do so, it is necessary to use and expand...Reducing CO2 emissions and restraining dependence on nuclear power generation are serious concerns in the prevention of global warming since the Great East Japan Earthquake. To do so, it is necessary to use and expand natural renewable energy source such as solar energy and to promote energy conservation. However, in high-latitude regions, it is difficult to directly and effectively use solar power due to on insufficient amount of solar radiation. If steam can be generated from warm water at less than 373 K, it is possible to obtain steam by solar water heaters from weak solar radiation and industrial waste warm water without the consumption of any fossil fuels. In this study, the authors have been developing a system which generates steam over 423 K from warm water at less than 373 K using an adsorption heat pump with zeolite. Therefore, bench-scale equipment which generates steam continuously and the experimental results are mentioned.展开更多
As the total amount and share of new energy installed capacity continue to rise,the demand for flexible regulation capability of the power system is becoming more and more prominent.The current conventional molten sal...As the total amount and share of new energy installed capacity continue to rise,the demand for flexible regulation capability of the power system is becoming more and more prominent.The current conventional molten salt energy storage system has insufficient peaking capacity.A solar-molten salt energy storage system based on multiple heat sources is constructed in this study.The heat generated from the solar field and the steams are used for the peaking process to further enhance the peaking capacity and flexibility.The installation multi-stage steam extraction and the introduction of an external heat source significantly improve the system performance.The simulation models based on EBSILON software are developed and the effects of key parameters on performance are discussed.The feasibility of the proposed system is further evaluated in terms of exergy and economy.The results demonstrate that the proposed SF-TES-CFPP(solar field,thermal energy storage system,coal-fired power plant)system exhibits the enhancement of peaking capability and flexible operation.In comparison with the conventional TES-CFPP,the integration of solar energy into the peaking process has enabled the SF-TES-CFPP system to enhance its peaking capacity by 20.60 MW while concurrently reducing the coal consumption rate by 10.26 g/kWh.The round-trip efficiency of the whole process of the system can be up to 85.43%through the reasonable heat distribution.In addition,the exergy loss of the principal components can be diminished and the exergy efficiency of the system can be augmented by selecting an appropriate main steam extraction mass and split ratio.The economic analysis demonstrates the dynamic payback period is 9.90 years with the net present value(NPV)across the entire life cycle reaching 1.06902×10^(9)USD.展开更多
The design and potential application analysis of the novel solar-absorbing integrated facade module and its corresponding building-integrated solar facade water heating system are presented in this study.Compared with...The design and potential application analysis of the novel solar-absorbing integrated facade module and its corresponding building-integrated solar facade water heating system are presented in this study.Compared with the conventional building envelope,the main novities of the proposed facade module lie in its contributions towards the supplied water preheating to loads and the internal heat gain reduction.Besides,the proposed building-integrated solar facade water heating system broadens the combination modes of the solar thermal system and the building envelope.A dynamic model is introduced first for system design and performance prediction.To evaluate the energy-saving potential and feasibility of the implementation of the proposed facade module,this paper carried out a suitable case study by replacing the conventional facade module in the ongoing retrofitting project of a kitchen,part of the canteen of a graduate school.The detailed thermal performances of three system design options are compared in the typical winter and summer weeks and throughout the year,and then,with the preferred system design,the economic,energy,and environmental effects of the proposed system are evaluated.It was found that the system with a high flow rate of the circulating water is suggested.The annual electricity saved reaches 4175.3 kWh with yearly average thermal efficiency at 46.9%,and its corresponding cost payback time,energy payback time,and greenhouse gas payback time are 3.8,1.7,1.7 years,respectively.This study confirms the feasibility and long-term benefits of the proposed building-integrated solar facade water heating system in buildings.展开更多
Refrigeration challenges in regions with electricity shortages significantly decrease the quality of life for residents. In response to the prevalent refrigeration challenges in power-deficient areas, a novel distribu...Refrigeration challenges in regions with electricity shortages significantly decrease the quality of life for residents. In response to the prevalent refrigeration challenges in power-deficient areas, a novel distributed solar refrigeration system, comprising an evacuated U-tube solar collector and elastocaloric refrigerator, is theoretically introduced. Theoretical formulations for the energy efficiency and cooling power of the solar refrigeration system are presented to facilitate predictive assessments of the performance properties. Under typical conditions, the energy efficiency and cooling power of the solar refrigeration system are,respectively, 4.84% and 200.15 W. Subsequently, an extensive parameter study is conducted to comprehensively uncover key performance influencers and identify avenues for improvement. In addition, local sensitivity analyses identify that the length ratio is the top influential parameter, while the heat transfer fluid flow rate is the least sensitivity. A pragmatic case study,conducted with the weather data of Ningbo City, China, serves to empirically predict the performance of the hybrid system within the constraints of practical circumstances.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 52106099)the Taishan Scholars Program。
文摘Direct absorption solar collectors use nanofluids to absorb and convert solar radiation. Despite the limitations of the photothermal properties of these nanofluids within the absorption spectra range, modifying the surface structure of the nanoparticles can broaden their absorption spectrum, thereby significantly improving the solar thermal conversion efficiency. This paper utilizes the finite element method to investigate the influence of surface pits on the photothermal properties of plasmonic nanoparticles, considering both material composition and surface micro-nano structures. Based on the findings, a novel Ti N nanoparticle is proposed to enhance photothermal performance. This nanoparticle exhibits the lowest average reflectance(0.0145) in the 300–1100 nm wavelength range and the highest light absorption intensity across the solar spectrum, enabling highly efficient solar energy conversion. It not only reduces material costs but also effectively broadens the light absorption spectrum of spherical plasmonic nanoparticles. The distributions of the electric field, magnetic field, and energy field of the nanoparticles indicate that the combination of the “lightning rod” effect and surface plasmon resonance(SPR) significantly enhances both the electric and magnetic fields, thereby increasing the localized heating effect and improving the photothermal performance. Additionally, the number and size of the pits have a significant impact on the absorption efficiency(η_(abs)) of TiN nanoparticles. When the surface of the nanoparticles has 38 pits, η_(abs) can reach90%, with the minimum optical penetration depth(h) of the nanofluid being 7 mm and the minimum volume fraction(f_(v))being 6.95×10^(-6). This study demonstrates that nanoparticles with micro-nano structures have immense potential in solar thermal applications, particularly in the field of direct absorption solar collectors.
基金This study is financially supported by the Excellent Youth Foundation of Jilin Province of China(Grant No.20190103062JH)the Special Project for the Outstanding Youth Cultivation of Jilin City of China(Grant No.20190104126).
文摘A unified theory of non-equilibrium radiation thermodynamics is always in search as it is meaningful for solar energy utilization.An exergy analysis of photo-thermal interaction process between the solar radiation energy and solar receiver is conducted in this paper.The non-equilibrium radiation thermodynamic system is described.The thermodynamic process of photo-thermal interaction between the solar radiation and solar receiver is introduced.Energy,exergy and entropy equations for the photo-thermal process are provided.Formulas for calculating the optimum receiving temperatures of the solar receiver under both non-concentration and solar concentration conditions are presented.A simple solar receiver is chosen as the calculation example to launch the exergy analysis under non-concentration condition.Furthermore,the effect analysis of solar concentration on the thermodynamic performance of the solar receiver for solar thermal utilization is carried out.The analysis results demonstrate that both the output exergy flux and efficiency of the solar receiver can be improved by increasing the solar concentration ratio during the solar thermal utilization process.The formulas and results provided in this paper may be used as a theoretical reference for the further studies of non-equilibrium radiation thermodynamic theory and solar thermal utilization.
文摘Reducing CO2 emissions and restraining dependence on nuclear power generation are serious concerns in the prevention of global warming since the Great East Japan Earthquake. To do so, it is necessary to use and expand natural renewable energy source such as solar energy and to promote energy conservation. However, in high-latitude regions, it is difficult to directly and effectively use solar power due to on insufficient amount of solar radiation. If steam can be generated from warm water at less than 373 K, it is possible to obtain steam by solar water heaters from weak solar radiation and industrial waste warm water without the consumption of any fossil fuels. In this study, the authors have been developing a system which generates steam over 423 K from warm water at less than 373 K using an adsorption heat pump with zeolite. Therefore, bench-scale equipment which generates steam continuously and the experimental results are mentioned.
基金supported by the National Key R&D Program(No.2022YFB4202404)。
文摘As the total amount and share of new energy installed capacity continue to rise,the demand for flexible regulation capability of the power system is becoming more and more prominent.The current conventional molten salt energy storage system has insufficient peaking capacity.A solar-molten salt energy storage system based on multiple heat sources is constructed in this study.The heat generated from the solar field and the steams are used for the peaking process to further enhance the peaking capacity and flexibility.The installation multi-stage steam extraction and the introduction of an external heat source significantly improve the system performance.The simulation models based on EBSILON software are developed and the effects of key parameters on performance are discussed.The feasibility of the proposed system is further evaluated in terms of exergy and economy.The results demonstrate that the proposed SF-TES-CFPP(solar field,thermal energy storage system,coal-fired power plant)system exhibits the enhancement of peaking capability and flexible operation.In comparison with the conventional TES-CFPP,the integration of solar energy into the peaking process has enabled the SF-TES-CFPP system to enhance its peaking capacity by 20.60 MW while concurrently reducing the coal consumption rate by 10.26 g/kWh.The round-trip efficiency of the whole process of the system can be up to 85.43%through the reasonable heat distribution.In addition,the exergy loss of the principal components can be diminished and the exergy efficiency of the system can be augmented by selecting an appropriate main steam extraction mass and split ratio.The economic analysis demonstrates the dynamic payback period is 9.90 years with the net present value(NPV)across the entire life cycle reaching 1.06902×10^(9)USD.
基金the financial supports from Foshan Science and Technology Innovation Project(2018IT100363)Guangdong Basic and Applied Basic Research Foundation(2022A1515110180)Guangdong Technology-transfer Center for the Commercialization of University-Innovations(zc01010000059).
文摘The design and potential application analysis of the novel solar-absorbing integrated facade module and its corresponding building-integrated solar facade water heating system are presented in this study.Compared with the conventional building envelope,the main novities of the proposed facade module lie in its contributions towards the supplied water preheating to loads and the internal heat gain reduction.Besides,the proposed building-integrated solar facade water heating system broadens the combination modes of the solar thermal system and the building envelope.A dynamic model is introduced first for system design and performance prediction.To evaluate the energy-saving potential and feasibility of the implementation of the proposed facade module,this paper carried out a suitable case study by replacing the conventional facade module in the ongoing retrofitting project of a kitchen,part of the canteen of a graduate school.The detailed thermal performances of three system design options are compared in the typical winter and summer weeks and throughout the year,and then,with the preferred system design,the economic,energy,and environmental effects of the proposed system are evaluated.It was found that the system with a high flow rate of the circulating water is suggested.The annual electricity saved reaches 4175.3 kWh with yearly average thermal efficiency at 46.9%,and its corresponding cost payback time,energy payback time,and greenhouse gas payback time are 3.8,1.7,1.7 years,respectively.This study confirms the feasibility and long-term benefits of the proposed building-integrated solar facade water heating system in buildings.
基金supported by the Baima Lake Laboratory Joint Funds of the Zhejiang Natural Science Foundation of China(Grant No.LBMHY24E060010)。
文摘Refrigeration challenges in regions with electricity shortages significantly decrease the quality of life for residents. In response to the prevalent refrigeration challenges in power-deficient areas, a novel distributed solar refrigeration system, comprising an evacuated U-tube solar collector and elastocaloric refrigerator, is theoretically introduced. Theoretical formulations for the energy efficiency and cooling power of the solar refrigeration system are presented to facilitate predictive assessments of the performance properties. Under typical conditions, the energy efficiency and cooling power of the solar refrigeration system are,respectively, 4.84% and 200.15 W. Subsequently, an extensive parameter study is conducted to comprehensively uncover key performance influencers and identify avenues for improvement. In addition, local sensitivity analyses identify that the length ratio is the top influential parameter, while the heat transfer fluid flow rate is the least sensitivity. A pragmatic case study,conducted with the weather data of Ningbo City, China, serves to empirically predict the performance of the hybrid system within the constraints of practical circumstances.
