This work aims at the mathematical modeling of a parabolic trough concentrator, the numerical resolution of the resulting equation, as well as the simulation of the heat transfer fluid heating process. To do this, a t...This work aims at the mathematical modeling of a parabolic trough concentrator, the numerical resolution of the resulting equation, as well as the simulation of the heat transfer fluid heating process. To do this, a thermal balance was established for the heat transfer fluid, the absorber and the glass. This allowed us to establish an equation system whose resolution was done by the finite difference method. Then, a computer program was developed to simulate the temperatures of the heat transfer fluid, the absorber tube and the glass as a function of time and space. The numerical resolution made it possible to obtain the temperatures of the heat transfer fluid, the absorber and the glass. The simulation of the fluid heating process was done in one-hour time steps, from six in the morning to six in the afternoon. The results obtained show that the temperature difference between the inlet and the outlet of the sensor is very significant. These results obtained, regarding the variation of the temperatures of the heat transfer fluid, the absorber and the glass, as well as the powers and efficiency of the parabolic trough concentrator and various factors, allow for the improvement of the performances of our prototype.展开更多
Facile and efficient method for constructing carbon dots(CDs)with narrow full width at half maximum(FWHM)is a major challenge in the field,and researches on regulating the FWHM of CDs are also rare and scarce.In this ...Facile and efficient method for constructing carbon dots(CDs)with narrow full width at half maximum(FWHM)is a major challenge in the field,and researches on regulating the FWHM of CDs are also rare and scarce.In this work,we delved into the synthesis of CDs with narrow fluorescence emission FWHM(NFEF-CDs)in the m-phenylenediamine(m-PD)/ethanol system,utilizing solid superacid resin as cata-lyst with solvothermal method.The resulting NFEF-CDs exhibit a photoluminescent(PL)emission peak at 521 nm with a narrow FWHM of 41 nm,an absolute PL quantum yield(QY)of 80%,and display excitation-independent PL behavior.Through comprehensive characterization,we identified the protonation of edge amino on NFEF-CDs as the key factor in achieving the narrow FWHM.Subsequently,we validated the broad applicability of solid superacid resins as catalysts for synthesizing CDs with narrow FWHM in the m-PD/ethanol system.Finally,we utilized a self-leveling method to prepare NFEF-CDs film on the surface of poly(methyl methacrylate)(PMMA)substrate and investigated the solid-state fluorescence properties of NFEF-CDs as well as their performance as luminescence solar concentrator(LSC)for photovoltaic conver-sion.The results revealed that the as-prepared LSC exhibit an internal quantum efficiency(η_(int))of 42.39%and an optical efficiency(η_(opt))of 0.68%.These findings demonstrate the promising prospects of NFEF-CDs in the field of LSCs and provide a theoretical basis for their application in photovoltaic conversion.展开更多
Harnessing the freely available source of energy from the sun offers a number of additional benefits. Not least of these benefits is the fact that solar energy is an environmentally sustainable alternative. A four-win...Harnessing the freely available source of energy from the sun offers a number of additional benefits. Not least of these benefits is the fact that solar energy is an environmentally sustainable alternative. A four-wing compound parabolic concentrator (CPC) was designed as a modification of the regular non-imaging CPC concentrator that has a widespread use as solar collector. The design is intended to increase the angle of acceptance as well as concentration of energy from the sun. The conceptual design, mathematical formulation as well as construction and initial trial results have been presented in this paper. Pilot trials of the four-wing concentrator used for sanitizing both liquid and waste products produced satisfactory results. Improvements in terms of design as well as material used for construction and better preservation of heat can be considered further in the future research.展开更多
The nonuniform irradiation in the standard photovoltaic（PV） cells causes their relatively high series resistance,which results in a considerably lowered efficiency of PV cells.Currently the concentrator of uniform i...The nonuniform irradiation in the standard photovoltaic（PV） cells causes their relatively high series resistance,which results in a considerably lowered efficiency of PV cells.Currently the concentrator of uniform irradiation designed for concentrator photovoltaic is rare in China and lack sufficient theoretical research.In this paper,a systematic research on the solar reflective concentrator is conducted.A novel structure for a solar reflective concentrator is designed with the application of a flat mirror matrix to concentrate the sunlight for concentrator photovoltaic（CPV） systems.Sunlight beams are focused through the reflection of the mirror array on the solar cell to generate electricity.The concentrator is capable of producing much more uniform sunlight with a certain concentration ratio.The design scheme includes laying out the flat mirrors,optimizing the optical pathway and the parameters of each mirror.The prototype of the CPV system was installed at Nanjing,China.In the configuration of the prototype,it is composed of 24 pieces parallelogram flat mirrors,which are arranged into a total reflective array of 5 rows and 5 columns.In comparison with the parabolic trough concentrator,the experimental measurements verify such design has high efficiency.The concentrator model of a flat mirror matrix and the proposed new design method will lay a solid foundation for designing the concentrator of uniform irradiation.展开更多
In order to improve structure performance of the dish solar concentrator,a three-dimensional model of dish solar concentrator was established based on the high-precision numerical algorithms.And a virtual wind tunnel ...In order to improve structure performance of the dish solar concentrator,a three-dimensional model of dish solar concentrator was established based on the high-precision numerical algorithms.And a virtual wind tunnel experiment with constant wind is adopted to investigate the pressure distribution of the reflective surface,velocity distribution of the fluid domain for the dish solar concentrator in different poses and wind speeds distribution.Some results about wind pressure distribution before and after dish solar concentrator surface and wind load velocity distribution in the entire fluid domain had been obtained.In particular,it is necessary to point out that the stiffness at the center of the dish solar concentrator should be relatively raised.The results can provide a theoretical basis for the improvement of solar concentrator dish structure as well as the failure analysis of dish solar concentrator in engineering practice.展开更多
The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the sol...The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanidedoped surface-functionalized ionosilicas(ISs)embedded in poly(methyl methacrylate)(PMMA)coated on the surface of commercial Si-based PV cells.The IS-PMMA hybrid materials exhibit efficient solar radiation harvesting(spectral overlap of^9.5×10^19 photons/(s·m2))and conversion(quantum yield^52%).The direct solar radiation and the down-shifted radiation are partially guided and lost through total internal reflection to the layer edges being unavailable for PV conversion of the coated PV cell.By tuning the down-shifting layer thickness,it also acts as luminescent solar concentrator enabling the collection of the guided radiation by flexible PV cells applied on the borders of the down-shifting layer leading to an enhancement of the PV energy conversion from^5%(in the case of the single-use of the luminescent down-shifting layer)to^13%comparing with the bare PV cell.The overall electrical output of the device resulted in an absolute external quantum efficiency increase of^32%for the optimized Eu^3+-based films in the UV spectral region(compared with the bare PV device,which is among the best values reported so far).展开更多
The accelerated life test was carded out to investigate the change of spectral transmittance of di-methyl silicon oil and the effects on the electrical performance of silicon solar cell. The di-methyl silicon oil samp...The accelerated life test was carded out to investigate the change of spectral transmittance of di-methyl silicon oil and the effects on the electrical performance of silicon solar cell. The di-methyl silicon oil samples be- fore and after accelerated life test were analyzed by FT-IR, GC-MS and LC-MS. The ring compounds and linear compounds with larger molecular weight were detected. The spectral transmittance of di-methyl silicon oil de- creased because the chromophore and auxochrome of the products made a sunlight receive decrease on the surface of the solar celt, and resulted in the reduction of cell performance. According to the decrease of spectral transmit- tance of di-methyl silicon oil, two recovery methods were proposed. The results showed that extraction was supe- rior to vacuum distillation in recovering the aged di-methyl silicon oil.展开更多
Objective: To analyze the biomechanical elements of Nitinol Patellar Concentrator (NT-PC) in heating commi nuted patellar fractures. Methods: The epoxy resin three dimensional photoelasticity pobal model was loaded wi...Objective: To analyze the biomechanical elements of Nitinol Patellar Concentrator (NT-PC) in heating commi nuted patellar fractures. Methods: The epoxy resin three dimensional photoelasticity pobal model was loaded with Nitinol Patellar Connector and frozen. After dividing layer, photographing and tracing, iterative method was used to calculate the stress value of every tuteed node. Rasults: Stress values of 1 262 nodes scattered in 12 layers were obtained The stress distribution indicated that an overall stress field was yield when the NT-PC fixated the patellar model, and there existed fixative stress in the facies articularis and distal pole of the patellar model. Conclusion: The NT-PC has evident therapeutic effect for the comminuted patellar fractures. The existing stress is helpful in maintaining anatomical reduction and enhancing fracture healing.展开更多
Physical methods show great potential and advantages on comprehensive reutilization of waste printed circuit boards (PCBs) because of lower investment and operation cost, higher efficiency and environment friendliness...Physical methods show great potential and advantages on comprehensive reutilization of waste printed circuit boards (PCBs) because of lower investment and operation cost, higher efficiency and environment friendliness. However, metals contained in fine fraction of PCBs cannot be recovered effectively by conventional equipments such as high tension electrostatic separator or shaking table. In the paper, this conundrum was resolved successfully with the enhanced Falcon SB concentrator. The separation mechanism of Falcon SB concentrator was analyzed and main factors affecting separation efficiency such as magnitude of rotation frequency of bowl, water counter pressure and slurry concentration of feed were studied and interaction of factors above also were investigated using Design-Expert software. Experiment results show that complete liberation degree and great difference of density between metals and nonmetals are suitable to recover metals from -74 μm PCBs using enhanced Falcon SB concentrator and 80.77 % integration efficiency can be achieved when slurry concentration of feed is 40 g/L with the water counter pressure of 0.01 MPa and rotation frequency of 50 Hz.展开更多
Positron sources are one of the most important components of the injector of a circular electron positron collector(CEPC).The CEPC is designed as an e^(+)e^(−)collider for a Higgs factory.Its accelerator system is com...Positron sources are one of the most important components of the injector of a circular electron positron collector(CEPC).The CEPC is designed as an e^(+)e^(−)collider for a Higgs factory.Its accelerator system is composed of 100-km-long storage rings and an injector.The design goal of the positron source is to obtain positron beams with a bunch charge of 3 nC.The flux concentrator(FC)is one of the cores of the positron source.This paper reports the design,development,and measurements of an FC prototype system.The prototype includes an FC and an all-solid-state high-current pulse modulator.Preliminary tests show that the peak current on the FC can reach 15.5 kA,and the peak magnetic field can reach 6.2 T.The test results are consistent with the theoretical simulation.The FC system fulfills the requirements of the CEPC positron source as well as provides a reference for the development of similar devices both domestically and abroad.展开更多
A unique method is proposed to encapsulate solar cells and improve their power conversion efficiency by using a millimeter-sized cylindrical lens array concentrator. Millimeter-sized epoxy resin polymer（ERP） cylindr...A unique method is proposed to encapsulate solar cells and improve their power conversion efficiency by using a millimeter-sized cylindrical lens array concentrator. Millimeter-sized epoxy resin polymer（ERP） cylindrical lens array concentrators are fabricated by the soft imprint technique based on polydimethylsiloxane stamps. The photovoltaic measurements show that millimeter-sized ERP cylindrical lens array concentrators can considerably improve the power conversion efficiency of silicon solar cells. The validity of the proposed method is proved by the coupled optical and electrical simulations. The designed solar cell devices with the advantages of high-efficiency and convenient cleaning are very useful in practical applications.展开更多
A new transparent photovoltaic panel composed of a luminescent solar concentrator and Al/BaTiO3/ZnO/Pt ferroelectric solar cells is presented,in which a portion of the incoming solar illumination is converted by the f...A new transparent photovoltaic panel composed of a luminescent solar concentrator and Al/BaTiO3/ZnO/Pt ferroelectric solar cells is presented,in which a portion of the incoming solar illumination is converted by the fluorophores to ultraviolet(UV)light which is then absorbed by ZnO.Firstly,the solar cells are simulated using Atlas-Silvaco.Then,the panel is modelled based on the obtained solar cell characteristics.This panel would be of great importance for building integrated photovoltaics domain because of its high transparency.展开更多
There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).A...There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).As an application of the MET,we selected the task of production of solar concentrators.Different types of solar concentrators with flat mirrors were developed and prototypes of these solar concentrators(approximately 1 m in diameter)were made.The proposed solar concentrators were developed on the basis of concentrators patented in Mexico,Spain,and USA.It may be possible to install these concentrators on horizontal roofs of buildings.However,installing them on agricultural fields has become the new trend.As an example,we propose to use them in the potato fields in Canada to obtain dual advantages such as for electrical energy generation and for the minimal loss of agricultural harvest.The second example was analyzed for bean fields,in Mexico.In this paper,we describe the main results in regard to microequipment development for solar concentrator production,several prototypes of solar concentrators with flat mirrors and their co-location and agricultural fields.展开更多
Transparent luminescent solar concentrator(LSC)is extensively regarded as the most promising sunlight tapping device for its application in buildings integrated with photovoltaics(BIPV)or as solar window glass.Convent...Transparent luminescent solar concentrator(LSC)is extensively regarded as the most promising sunlight tapping device for its application in buildings integrated with photovoltaics(BIPV)or as solar window glass.Conventional LSCs doped with organic dyes suffered from high reabsorption losses with no transparency;whereas,recently reported heavy metal-doped quantum dots avoided such losses but possessed the risk of high toxicity and low ambient stability.Thus,luminophores with massive spectral shifts and co rdial relationships with the enviro nment are very much desirable.In this paper,we report the fabrication of PMMA based transparent LSC embedded with nanocrystals of environmental friendiness and multispectral harvesting gadolinium oxysulphide(Gd_(2)O_(2) S:Er,Yb)fluorophore.The Gd_(2)O_(2) S:Er,Yb nanofluorophore absorbs various excitation wavelengths ranging from UV to NIR and emits in the visible region offering huge Stoke’s and anti-Stoke’s shift concurrently.The non-existent reabsorption losses and overlapping maxima of Gd_(2)O_(2) S:Er,Yb nanofluorophore generated photon flux with solar cells’responsivity enhance the efficiency characteristics of the LSC waveguide.Performance analysis of LSC as a function of varying nanofluorophore dispersion ratio and changing edge width optimizes the fabrication process and exhibits high power conversion efficiency of-6,93%and optical efficiency of-8.57%.The LSC slab demonstrates high photostability under irradiation for prolonged hours without any dip in the emission characteristics.The Gd_(2)O_(2) S:Er,Yb nanofluorophore diffused LSC waveguide offering spectral tunability,cost-reduction,efficiency enhancement,and high concentration factor whilst being sustainable for long term use makes it a fascinating transparent solar window.展开更多
A metal plate cooling model for 400~ single concentrator solar cells was established. The effects of the thickness and the radius of the metal plate, and the air environment on the temperature of the solar cells were ...A metal plate cooling model for 400~ single concentrator solar cells was established. The effects of the thickness and the radius of the metal plate, and the air environment on the temperature of the solar cells were analyzed in detail. It is shown that the temperature of the solar cells decreased sharply at the beginning, with the increase in the thickness of the metal plate, and then changed more smoothly. When the radius of the metal plate was 4 cm and the thickness increased to 2 mm or thicker, the temperature of the solar cell basically stabilized at about 53℃. Increasing the radius of the metal plate and the convective transfer coefficient made the temperature of the solar cell decrease remarkably. The effects of A1 and Cu as the metal plate material on cooling were analyzed contrastively, and demonstrated the superiority of A1 material for the cooling system. Furthermore, considering cost reduction, space holding and the stress of the system, we optimized the structural design of the metal plate. The simulated results can be referred to the design of the structure for the metal plate. Finally, a method to devise the structure of the metal plate for single concentrator solar cells was given.展开更多
A single concentrator solar cell model with a heat sink is established to simulate the thermal performance of the system by varying the number, height, and thickness of fins, the base thickness and thermal resistance ...A single concentrator solar cell model with a heat sink is established to simulate the thermal performance of the system by varying the number, height, and thickness of fins, the base thickness and thermal resistance of the thermal conductive adhesive. Influence disciplines of those parameters on temperatures of the solar cell and heat sink are obtained. With optimized number, height and thickness of fins, and the thickness values of base of 8, 1.4 cm, 1.5 mm, and 2 mm, the lowest temperatures of the solar cell and heat sink are 41.7 ~C and 36.3 ~C respectively. A concentrator solar cell prototype with a heat sink fabricated based on the simulation optimized structure is built. Outdoor temperatures of the prototype are tested. Temperatures of the solar cell and heat sink are stabilized with time continuing at about 37 ℃-38 ℃ and 35 ℃-36 ℃respectively, slightly lower than the simulation results because of effects of the wind and cloud. Thus the simulation model enables to predict the thermal performance of the system, and the simulation results can be a reference for designing heat sinks in the field of single concentrator solar cells.展开更多
A passive current sensor,consisting of SmFe_(2)/PZT/SmFe_(2)self-biased magnetoelectric(ME)composite and Fe_(73.5)Cu_(1)Nb_(3)Si_(13.5)B_(9)nanocrystalline flux concentrator for weak current detection at power-line fr...A passive current sensor,consisting of SmFe_(2)/PZT/SmFe_(2)self-biased magnetoelectric(ME)composite and Fe_(73.5)Cu_(1)Nb_(3)Si_(13.5)B_(9)nanocrystalline flux concentrator for weak current detection at power-line frequency,was fabricated and characterized.Giant magnetostrictive material of SmFe_(2)plate with large anisotropic constant provides a huge internal anisotropic field to bias the ME transducer in closed magnetic loop.Consequently,the additional magnetomotive force induced by the internal field and the corresponding increased effective permeabil-ity contribute to the improvement of the sensitivity.Experimental results demonstrate that the presented sensor has a higher sensitivity of 152 mV·A^(-1)at 50 Hz with a slight nonlinearity of~0.01%full scale(FS)and matches well with the predicted value.This presented current-sensing device exhibits approximately 2.3 times higher sensitivity than that of conventional ME composite with[Pb(Zr_(0.48),Ti_(0.52)O_(3)](PZT)and Terfenol-D plates serving as a key sensitive component.In addition,time stabilities of the presented sensor were evaluated for a long period of 72 h and analyzed through mathematical statistics method,and favorable stabilities with an uncertainty of 0.5μV are obtained in continuous 1 h testing.These results provide a significant advancement toward promising application of the tri-layer self-biased ME laminate for power-line elec-tric cords monitoring.展开更多
An analysis of the thermal characteristics of the industrial thermocompression heat pump systems is presented in this paper By using thermocompression, waste heat is thermotransformed to a higher temperature level to ...An analysis of the thermal characteristics of the industrial thermocompression heat pump systems is presented in this paper By using thermocompression, waste heat is thermotransformed to a higher temperature level to be convenient for its usage in thermal processes. The thermocompression heat pumps can be optimally applied in various industrial plants （production of fruit, grape and tomato concentrates, in beer, sugar and dairy industries, in chemical and pharmaceutical industries etc.）. The range of optimal application of the turbo compressor, screw compressor and ejector thermocompression is estimated. The complex thermal and flow phenomena in the processes of thermocompression, evaporation and condensation are discussed. The theoretical and experimental results of the investigations on the experimental grape vacuum concentrator and on the industrial NaOH concentrator are presented. A significant increment of the energy efficiency can be achieved by optimal application of the thermocompression in the thermal concentrating processes. A significant feature and great advantage of the concentrating technology with thermocompression are a possibility for realization of the low temperature concentrating processes, which is very important for the quality of many concentrating products with high energy efficiency technology.展开更多
The main geometrical and operating parameters of the water steam centrifugal compressors working in various concentrator operating conditions are realized in this paper. The interdependence between centrifugal stage p...The main geometrical and operating parameters of the water steam centrifugal compressors working in various concentrator operating conditions are realized in this paper. The interdependence between centrifugal stage pressure ratio, peripheral Mach number and impeller peripheral speed, as well the influence of the concentrator system capacity on the dimensions of the centrifugal compressor are determined to obtain the range of reasonable usage of the centrifugal thermocompression systems in the industrial concentrators. The high peripheral impeller speed, high Mach number and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the water steam centrifugal compressor flow field. The calculating methods for 3-D viscid unsteady transonic fluid flows in the turbocompressors are discussed and the results of CFD simulations and experimental investigations are used for optimal design of the water steam centrifugal compressor flow field. The application of the centrifugal compressor in the industrial concentrators with thermocompression systems and the influence on the energy efficiency of the systems are analyzed. Significant increment of the energy efficiency of the industrial concentrators can be achieved by introduction of the thermocompression systems.展开更多
There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cookin...There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cooking efficiency and cooking capacity. Apart from thermal efficiency, there is an imperative need for other important parameters of the solar concentrators such as its stagnation temperature, cooking capacity, cost per watts delivered, weight of the cooker, ease of handling and aesthetics. The characterization of a concentrator at its operating temperature settles appropriate size and type of concentrator for any thermal application. The performance test is conducted at Chandwad (20.3292°N, 74.2444°E), Maharashtra and the proposed protocol aims for evaluation of thermal performance of solar cooking system and standardization of reporting the test results so that anyone can easily recognize and use it.展开更多
文摘This work aims at the mathematical modeling of a parabolic trough concentrator, the numerical resolution of the resulting equation, as well as the simulation of the heat transfer fluid heating process. To do this, a thermal balance was established for the heat transfer fluid, the absorber and the glass. This allowed us to establish an equation system whose resolution was done by the finite difference method. Then, a computer program was developed to simulate the temperatures of the heat transfer fluid, the absorber tube and the glass as a function of time and space. The numerical resolution made it possible to obtain the temperatures of the heat transfer fluid, the absorber and the glass. The simulation of the fluid heating process was done in one-hour time steps, from six in the morning to six in the afternoon. The results obtained show that the temperature difference between the inlet and the outlet of the sensor is very significant. These results obtained, regarding the variation of the temperatures of the heat transfer fluid, the absorber and the glass, as well as the powers and efficiency of the parabolic trough concentrator and various factors, allow for the improvement of the performances of our prototype.
基金supported by the National Natural Science Foundation of China(No.22308161)the Jiangsu Funding Program for Excellent Postdoctoral Talent(No.2022ZB369),Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Facile and efficient method for constructing carbon dots(CDs)with narrow full width at half maximum(FWHM)is a major challenge in the field,and researches on regulating the FWHM of CDs are also rare and scarce.In this work,we delved into the synthesis of CDs with narrow fluorescence emission FWHM(NFEF-CDs)in the m-phenylenediamine(m-PD)/ethanol system,utilizing solid superacid resin as cata-lyst with solvothermal method.The resulting NFEF-CDs exhibit a photoluminescent(PL)emission peak at 521 nm with a narrow FWHM of 41 nm,an absolute PL quantum yield(QY)of 80%,and display excitation-independent PL behavior.Through comprehensive characterization,we identified the protonation of edge amino on NFEF-CDs as the key factor in achieving the narrow FWHM.Subsequently,we validated the broad applicability of solid superacid resins as catalysts for synthesizing CDs with narrow FWHM in the m-PD/ethanol system.Finally,we utilized a self-leveling method to prepare NFEF-CDs film on the surface of poly(methyl methacrylate)(PMMA)substrate and investigated the solid-state fluorescence properties of NFEF-CDs as well as their performance as luminescence solar concentrator(LSC)for photovoltaic conver-sion.The results revealed that the as-prepared LSC exhibit an internal quantum efficiency(η_(int))of 42.39%and an optical efficiency(η_(opt))of 0.68%.These findings demonstrate the promising prospects of NFEF-CDs in the field of LSCs and provide a theoretical basis for their application in photovoltaic conversion.
文摘Harnessing the freely available source of energy from the sun offers a number of additional benefits. Not least of these benefits is the fact that solar energy is an environmentally sustainable alternative. A four-wing compound parabolic concentrator (CPC) was designed as a modification of the regular non-imaging CPC concentrator that has a widespread use as solar collector. The design is intended to increase the angle of acceptance as well as concentration of energy from the sun. The conceptual design, mathematical formulation as well as construction and initial trial results have been presented in this paper. Pilot trials of the four-wing concentrator used for sanitizing both liquid and waste products produced satisfactory results. Improvements in terms of design as well as material used for construction and better preservation of heat can be considered further in the future research.
基金supported by National Natural Science Foundation of China (Grant No. 50775035)National Hi-tech Research and Development Program of China (863 Program,Grant No. 2006AA050203,Grant No. 2007AA04Z421)
文摘The nonuniform irradiation in the standard photovoltaic（PV） cells causes their relatively high series resistance,which results in a considerably lowered efficiency of PV cells.Currently the concentrator of uniform irradiation designed for concentrator photovoltaic is rare in China and lack sufficient theoretical research.In this paper,a systematic research on the solar reflective concentrator is conducted.A novel structure for a solar reflective concentrator is designed with the application of a flat mirror matrix to concentrate the sunlight for concentrator photovoltaic（CPV） systems.Sunlight beams are focused through the reflection of the mirror array on the solar cell to generate electricity.The concentrator is capable of producing much more uniform sunlight with a certain concentration ratio.The design scheme includes laying out the flat mirrors,optimizing the optical pathway and the parameters of each mirror.The prototype of the CPV system was installed at Nanjing,China.In the configuration of the prototype,it is composed of 24 pieces parallelogram flat mirrors,which are arranged into a total reflective array of 5 rows and 5 columns.In comparison with the parabolic trough concentrator,the experimental measurements verify such design has high efficiency.The concentrator model of a flat mirror matrix and the proposed new design method will lay a solid foundation for designing the concentrator of uniform irradiation.
基金Projects(201208430262,201306130031)supported by the China Scholarship Council
文摘In order to improve structure performance of the dish solar concentrator,a three-dimensional model of dish solar concentrator was established based on the high-precision numerical algorithms.And a virtual wind tunnel experiment with constant wind is adopted to investigate the pressure distribution of the reflective surface,velocity distribution of the fluid domain for the dish solar concentrator in different poses and wind speeds distribution.Some results about wind pressure distribution before and after dish solar concentrator surface and wind load velocity distribution in the entire fluid domain had been obtained.In particular,it is necessary to point out that the stiffness at the center of the dish solar concentrator should be relatively raised.The results can provide a theoretical basis for the improvement of solar concentrator dish structure as well as the failure analysis of dish solar concentrator in engineering practice.
基金Project supported by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership in the frame of Operational Competitiveness and Internationalization Programme(projects UIDB/50011/2020&UIDP/50011/2020,UID/EEA/50008/2020,UID/QUI/50006/2019,CENTRO-01-0145-FEDER-030186,CENTRO-01-0145-FEDER-000005,Pest-OE/QUI/UI0616/2014,POCI-01-0145-FEDER-016884,PTDC/CTM-NAN/0956/2014,UID/QUI/00686/2016,UID/QUI/00686/2018,UID/QUI/00686/2019 and NORTE-01-0145-FEDER-030858)。
文摘The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanidedoped surface-functionalized ionosilicas(ISs)embedded in poly(methyl methacrylate)(PMMA)coated on the surface of commercial Si-based PV cells.The IS-PMMA hybrid materials exhibit efficient solar radiation harvesting(spectral overlap of^9.5×10^19 photons/(s·m2))and conversion(quantum yield^52%).The direct solar radiation and the down-shifted radiation are partially guided and lost through total internal reflection to the layer edges being unavailable for PV conversion of the coated PV cell.By tuning the down-shifting layer thickness,it also acts as luminescent solar concentrator enabling the collection of the guided radiation by flexible PV cells applied on the borders of the down-shifting layer leading to an enhancement of the PV energy conversion from^5%(in the case of the single-use of the luminescent down-shifting layer)to^13%comparing with the bare PV cell.The overall electrical output of the device resulted in an absolute external quantum efficiency increase of^32%for the optimized Eu^3+-based films in the UV spectral region(compared with the bare PV device,which is among the best values reported so far).
基金Supported by the National Natural Science Foundation of China(No.51478297)Program of Introducing Talents of Discipline(No.B13011)
文摘The accelerated life test was carded out to investigate the change of spectral transmittance of di-methyl silicon oil and the effects on the electrical performance of silicon solar cell. The di-methyl silicon oil samples be- fore and after accelerated life test were analyzed by FT-IR, GC-MS and LC-MS. The ring compounds and linear compounds with larger molecular weight were detected. The spectral transmittance of di-methyl silicon oil de- creased because the chromophore and auxochrome of the products made a sunlight receive decrease on the surface of the solar celt, and resulted in the reduction of cell performance. According to the decrease of spectral transmit- tance of di-methyl silicon oil, two recovery methods were proposed. The results showed that extraction was supe- rior to vacuum distillation in recovering the aged di-methyl silicon oil.
文摘Objective: To analyze the biomechanical elements of Nitinol Patellar Concentrator (NT-PC) in heating commi nuted patellar fractures. Methods: The epoxy resin three dimensional photoelasticity pobal model was loaded with Nitinol Patellar Connector and frozen. After dividing layer, photographing and tracing, iterative method was used to calculate the stress value of every tuteed node. Rasults: Stress values of 1 262 nodes scattered in 12 layers were obtained The stress distribution indicated that an overall stress field was yield when the NT-PC fixated the patellar model, and there existed fixative stress in the facies articularis and distal pole of the patellar model. Conclusion: The NT-PC has evident therapeutic effect for the comminuted patellar fractures. The existing stress is helpful in maintaining anatomical reduction and enhancing fracture healing.
基金Project 200360290015 supported by the Doctoral Program of Higher Education, China Ministry of Education
文摘Physical methods show great potential and advantages on comprehensive reutilization of waste printed circuit boards (PCBs) because of lower investment and operation cost, higher efficiency and environment friendliness. However, metals contained in fine fraction of PCBs cannot be recovered effectively by conventional equipments such as high tension electrostatic separator or shaking table. In the paper, this conundrum was resolved successfully with the enhanced Falcon SB concentrator. The separation mechanism of Falcon SB concentrator was analyzed and main factors affecting separation efficiency such as magnitude of rotation frequency of bowl, water counter pressure and slurry concentration of feed were studied and interaction of factors above also were investigated using Design-Expert software. Experiment results show that complete liberation degree and great difference of density between metals and nonmetals are suitable to recover metals from -74 μm PCBs using enhanced Falcon SB concentrator and 80.77 % integration efficiency can be achieved when slurry concentration of feed is 40 g/L with the water counter pressure of 0.01 MPa and rotation frequency of 50 Hz.
基金This work was supported by the National Key Programme for S&T Research and Development(No.2016YFA0400400)the Youth Innovation Promotion Association CAS(2019016).
文摘Positron sources are one of the most important components of the injector of a circular electron positron collector(CEPC).The CEPC is designed as an e^(+)e^(−)collider for a Higgs factory.Its accelerator system is composed of 100-km-long storage rings and an injector.The design goal of the positron source is to obtain positron beams with a bunch charge of 3 nC.The flux concentrator(FC)is one of the cores of the positron source.This paper reports the design,development,and measurements of an FC prototype system.The prototype includes an FC and an all-solid-state high-current pulse modulator.Preliminary tests show that the peak current on the FC can reach 15.5 kA,and the peak magnetic field can reach 6.2 T.The test results are consistent with the theoretical simulation.The FC system fulfills the requirements of the CEPC positron source as well as provides a reference for the development of similar devices both domestically and abroad.
基金Project supported by the Natural National Science Foundation of China(Grant No.61377021)
文摘A unique method is proposed to encapsulate solar cells and improve their power conversion efficiency by using a millimeter-sized cylindrical lens array concentrator. Millimeter-sized epoxy resin polymer（ERP） cylindrical lens array concentrators are fabricated by the soft imprint technique based on polydimethylsiloxane stamps. The photovoltaic measurements show that millimeter-sized ERP cylindrical lens array concentrators can considerably improve the power conversion efficiency of silicon solar cells. The validity of the proposed method is proved by the coupled optical and electrical simulations. The designed solar cell devices with the advantages of high-efficiency and convenient cleaning are very useful in practical applications.
文摘A new transparent photovoltaic panel composed of a luminescent solar concentrator and Al/BaTiO3/ZnO/Pt ferroelectric solar cells is presented,in which a portion of the incoming solar illumination is converted by the fluorophores to ultraviolet(UV)light which is then absorbed by ZnO.Firstly,the solar cells are simulated using Atlas-Silvaco.Then,the panel is modelled based on the obtained solar cell characteristics.This panel would be of great importance for building integrated photovoltaics domain because of its high transparency.
文摘There is an increased interest in renewable forms of energy across the world,with solar energy being one of the most promising forms.Over the last couple of years,we have developed the MET(MicroEquipment Technology).As an application of the MET,we selected the task of production of solar concentrators.Different types of solar concentrators with flat mirrors were developed and prototypes of these solar concentrators(approximately 1 m in diameter)were made.The proposed solar concentrators were developed on the basis of concentrators patented in Mexico,Spain,and USA.It may be possible to install these concentrators on horizontal roofs of buildings.However,installing them on agricultural fields has become the new trend.As an example,we propose to use them in the potato fields in Canada to obtain dual advantages such as for electrical energy generation and for the minimal loss of agricultural harvest.The second example was analyzed for bean fields,in Mexico.In this paper,we describe the main results in regard to microequipment development for solar concentrator production,several prototypes of solar concentrators with flat mirrors and their co-location and agricultural fields.
基金Project supported by Department of Science and Technology,Government of India(DST/TMD/CERI/C-24(g))。
文摘Transparent luminescent solar concentrator(LSC)is extensively regarded as the most promising sunlight tapping device for its application in buildings integrated with photovoltaics(BIPV)or as solar window glass.Conventional LSCs doped with organic dyes suffered from high reabsorption losses with no transparency;whereas,recently reported heavy metal-doped quantum dots avoided such losses but possessed the risk of high toxicity and low ambient stability.Thus,luminophores with massive spectral shifts and co rdial relationships with the enviro nment are very much desirable.In this paper,we report the fabrication of PMMA based transparent LSC embedded with nanocrystals of environmental friendiness and multispectral harvesting gadolinium oxysulphide(Gd_(2)O_(2) S:Er,Yb)fluorophore.The Gd_(2)O_(2) S:Er,Yb nanofluorophore absorbs various excitation wavelengths ranging from UV to NIR and emits in the visible region offering huge Stoke’s and anti-Stoke’s shift concurrently.The non-existent reabsorption losses and overlapping maxima of Gd_(2)O_(2) S:Er,Yb nanofluorophore generated photon flux with solar cells’responsivity enhance the efficiency characteristics of the LSC waveguide.Performance analysis of LSC as a function of varying nanofluorophore dispersion ratio and changing edge width optimizes the fabrication process and exhibits high power conversion efficiency of-6,93%and optical efficiency of-8.57%.The LSC slab demonstrates high photostability under irradiation for prolonged hours without any dip in the emission characteristics.The Gd_(2)O_(2) S:Er,Yb nanofluorophore diffused LSC waveguide offering spectral tunability,cost-reduction,efficiency enhancement,and high concentration factor whilst being sustainable for long term use makes it a fascinating transparent solar window.
基金Project supported by the Doctoral Initial Fund of Beijing University of Technology,China (Grant No. X0006015201101)the National Natural Science Foundation of China (Grant No. 10804005)
文摘A metal plate cooling model for 400~ single concentrator solar cells was established. The effects of the thickness and the radius of the metal plate, and the air environment on the temperature of the solar cells were analyzed in detail. It is shown that the temperature of the solar cells decreased sharply at the beginning, with the increase in the thickness of the metal plate, and then changed more smoothly. When the radius of the metal plate was 4 cm and the thickness increased to 2 mm or thicker, the temperature of the solar cell basically stabilized at about 53℃. Increasing the radius of the metal plate and the convective transfer coefficient made the temperature of the solar cell decrease remarkably. The effects of A1 and Cu as the metal plate material on cooling were analyzed contrastively, and demonstrated the superiority of A1 material for the cooling system. Furthermore, considering cost reduction, space holding and the stress of the system, we optimized the structural design of the metal plate. The simulated results can be referred to the design of the structure for the metal plate. Finally, a method to devise the structure of the metal plate for single concentrator solar cells was given.
基金supported by the Doctoral Initial Fund of Beijing University of Technology,China(Grant No.X0006015201101)the National Natural Science Foundation of China(Grant Nos.60876006 and 51202007)
文摘A single concentrator solar cell model with a heat sink is established to simulate the thermal performance of the system by varying the number, height, and thickness of fins, the base thickness and thermal resistance of the thermal conductive adhesive. Influence disciplines of those parameters on temperatures of the solar cell and heat sink are obtained. With optimized number, height and thickness of fins, and the thickness values of base of 8, 1.4 cm, 1.5 mm, and 2 mm, the lowest temperatures of the solar cell and heat sink are 41.7 ~C and 36.3 ~C respectively. A concentrator solar cell prototype with a heat sink fabricated based on the simulation optimized structure is built. Outdoor temperatures of the prototype are tested. Temperatures of the solar cell and heat sink are stabilized with time continuing at about 37 ℃-38 ℃ and 35 ℃-36 ℃respectively, slightly lower than the simulation results because of effects of the wind and cloud. Thus the simulation model enables to predict the thermal performance of the system, and the simulation results can be a reference for designing heat sinks in the field of single concentrator solar cells.
基金financially supported by the National High Technology Research and Development Program of China (No. 2012AA040602)the National Natural Science Foundation of China (No. 61374217)
文摘A passive current sensor,consisting of SmFe_(2)/PZT/SmFe_(2)self-biased magnetoelectric(ME)composite and Fe_(73.5)Cu_(1)Nb_(3)Si_(13.5)B_(9)nanocrystalline flux concentrator for weak current detection at power-line frequency,was fabricated and characterized.Giant magnetostrictive material of SmFe_(2)plate with large anisotropic constant provides a huge internal anisotropic field to bias the ME transducer in closed magnetic loop.Consequently,the additional magnetomotive force induced by the internal field and the corresponding increased effective permeabil-ity contribute to the improvement of the sensitivity.Experimental results demonstrate that the presented sensor has a higher sensitivity of 152 mV·A^(-1)at 50 Hz with a slight nonlinearity of~0.01%full scale(FS)and matches well with the predicted value.This presented current-sensing device exhibits approximately 2.3 times higher sensitivity than that of conventional ME composite with[Pb(Zr_(0.48),Ti_(0.52)O_(3)](PZT)and Terfenol-D plates serving as a key sensitive component.In addition,time stabilities of the presented sensor were evaluated for a long period of 72 h and analyzed through mathematical statistics method,and favorable stabilities with an uncertainty of 0.5μV are obtained in continuous 1 h testing.These results provide a significant advancement toward promising application of the tri-layer self-biased ME laminate for power-line elec-tric cords monitoring.
文摘An analysis of the thermal characteristics of the industrial thermocompression heat pump systems is presented in this paper By using thermocompression, waste heat is thermotransformed to a higher temperature level to be convenient for its usage in thermal processes. The thermocompression heat pumps can be optimally applied in various industrial plants （production of fruit, grape and tomato concentrates, in beer, sugar and dairy industries, in chemical and pharmaceutical industries etc.）. The range of optimal application of the turbo compressor, screw compressor and ejector thermocompression is estimated. The complex thermal and flow phenomena in the processes of thermocompression, evaporation and condensation are discussed. The theoretical and experimental results of the investigations on the experimental grape vacuum concentrator and on the industrial NaOH concentrator are presented. A significant increment of the energy efficiency can be achieved by optimal application of the thermocompression in the thermal concentrating processes. A significant feature and great advantage of the concentrating technology with thermocompression are a possibility for realization of the low temperature concentrating processes, which is very important for the quality of many concentrating products with high energy efficiency technology.
文摘The main geometrical and operating parameters of the water steam centrifugal compressors working in various concentrator operating conditions are realized in this paper. The interdependence between centrifugal stage pressure ratio, peripheral Mach number and impeller peripheral speed, as well the influence of the concentrator system capacity on the dimensions of the centrifugal compressor are determined to obtain the range of reasonable usage of the centrifugal thermocompression systems in the industrial concentrators. The high peripheral impeller speed, high Mach number and high pressure ratio cause separated jet-wake flow and transonic flow phenomena in the water steam centrifugal compressor flow field. The calculating methods for 3-D viscid unsteady transonic fluid flows in the turbocompressors are discussed and the results of CFD simulations and experimental investigations are used for optimal design of the water steam centrifugal compressor flow field. The application of the centrifugal compressor in the industrial concentrators with thermocompression systems and the influence on the energy efficiency of the systems are analyzed. Significant increment of the energy efficiency of the industrial concentrators can be achieved by introduction of the thermocompression systems.
文摘There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cooking efficiency and cooking capacity. Apart from thermal efficiency, there is an imperative need for other important parameters of the solar concentrators such as its stagnation temperature, cooking capacity, cost per watts delivered, weight of the cooker, ease of handling and aesthetics. The characterization of a concentrator at its operating temperature settles appropriate size and type of concentrator for any thermal application. The performance test is conducted at Chandwad (20.3292°N, 74.2444°E), Maharashtra and the proposed protocol aims for evaluation of thermal performance of solar cooking system and standardization of reporting the test results so that anyone can easily recognize and use it.
