SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems最新文献

{"title":"Preparation and characterization of nanofluids based on molten salts with enhanced thermophysical properties for thermal energy storage at concentrate solar power","authors":"Yaroslav Grosu, U. Nithiyanantham, L. González-Fernández, A. Faik","doi":"10.1063/1.5117736","DOIUrl":"https://doi.org/10.1063/1.5117736","url":null,"abstract":"In the recent years considerable interest of scientific and industrial communities in molten salts based nanofluids is evident. Such interest is motivated by the possibility of enhancement of thermophysical properties of molten salts by means of adding small concentrations of nanoparticles. This enhancement is particularly attractive for thermal energy storage systems at concentrated solar power plants, where molten salts are often used as a storage media as well as heat transfer fluid. Despite the high number of works reporting the effect of nanoparticles on thermophysical properties of molten salts, not only does the mechanism behind the observed enhancement remain mysterious, but the reported values are often contradicting. In this work we attempt to provide some guidelines for the preparation and characterization of nanofluids based on molten salts in order to avoid misleading interpretations regarding their thermophysical properties. We particularly focus on the importance of the preparation method and the stability of molten salt based nanofluids. We also discuss the formation of dendritic structures in molten salt doped with nanoparticles, which has been often related to thermophysical properties enhancement.In the recent years considerable interest of scientific and industrial communities in molten salts based nanofluids is evident. Such interest is motivated by the possibility of enhancement of thermophysical properties of molten salts by means of adding small concentrations of nanoparticles. This enhancement is particularly attractive for thermal energy storage systems at concentrated solar power plants, where molten salts are often used as a storage media as well as heat transfer fluid. Despite the high number of works reporting the effect of nanoparticles on thermophysical properties of molten salts, not only does the mechanism behind the observed enhancement remain mysterious, but the reported values are often contradicting. In this work we attempt to provide some guidelines for the preparation and characterization of nanofluids based on molten salts in order to avoid misleading interpretations regarding their thermophysical properties. We particularly focus on the importance of the preparation method a...","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81562545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards a more reliable evaluation of the Morocco’s solar resource","authors":"Asmae Azzioui, Moulay Hafid Bouhamidi, Mustapha Mouadine, M. Ettarid","doi":"10.1063/1.5117700","DOIUrl":"https://doi.org/10.1063/1.5117700","url":null,"abstract":"The current national energy policy aims to develop and promote renewable and clean energy. To this end, one of the Morocco’s most available energies that could contribute appreciably to improving national energy mix is solar energy. Thus; any solar project must rely (at least in large part) on modeled (satellite-based) irradiance data. However, a key question remains: the reliability of these data sets and generated maps. It is in this outlook that our study comes to highlight the problems with the assessment of the solar resource and to stress the concept of the calibration of satellite data to ground measurements (site-specific adaptation). In order to achieve this desired goal, we have introduced the different procedures of local calibration used in the solar energy industry and operated the calibration of the Moroccan Solar Atlas (MSA). In this context, an innovative protocol of generalization of the calibration to cover the entire territory of Morocco has been implemented and has demonstrated the quality of the proposed method and its contribution compared to conventional methods.The current national energy policy aims to develop and promote renewable and clean energy. To this end, one of the Morocco’s most available energies that could contribute appreciably to improving national energy mix is solar energy. Thus; any solar project must rely (at least in large part) on modeled (satellite-based) irradiance data. However, a key question remains: the reliability of these data sets and generated maps. It is in this outlook that our study comes to highlight the problems with the assessment of the solar resource and to stress the concept of the calibration of satellite data to ground measurements (site-specific adaptation). In order to achieve this desired goal, we have introduced the different procedures of local calibration used in the solar energy industry and operated the calibration of the Moroccan Solar Atlas (MSA). In this context, an innovative protocol of generalization of the calibration to cover the entire territory of Morocco has been implemented and has demonstrated the qua...","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78509429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning for solar trackers","authors":"J. Carballo, J. Bonilla, M. Berenguel, J. Fernández-Reche, Ginés García","doi":"10.1063/1.5117524","DOIUrl":"https://doi.org/10.1063/1.5117524","url":null,"abstract":"A new approach for solar tracking, based on deep learning techniques, is being studied and tested using Tensorflow, an open source machine learning framework. Tensorflow makes the implementation more flexible and increases the development capabilities. Tensorflow facilitates the neural network implementation on several kinds of devices (embedded and mobile devices, mini computers, etc.). Furthermore, Tensorflow supports different types of neural networks which can be tuned and retrained for particular purposes. The presented results are promising, since the retrained networks correctly identify the Sun and the target, with this information the system can be controlled to properly track the Sun’s apparent trajectory without further information.","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79279345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Corrosion monitoring of ferritic-martensitic steels in molten salt environments for CSP applications","authors":"F. Pérez, V. Encinas-Sánchez, M. I. Lasanta, M. Miguel, G. García-Martin","doi":"10.1063/1.5117552","DOIUrl":"https://doi.org/10.1063/1.5117552","url":null,"abstract":"In the present work, the behaviour of a ferritic-martensitic steel, VM12, in Solar Salt was monitored by EIS. To this end corrosion tests at 580°C were carried out for 1000 h. According to the EIS results, a diffusion-controlled reaction occurred during test, which indicates the formation of a porous corrosion layer. The EIS results also shown a corrosion rate of 50 µm·year−1 after 1000 h of testing. Results obtained by EIS were in agreement with the ones obtained by gravimetric and SEM-EDX analysis. Thus, results showed the possible suitability of EIS for monitoring corrosion processes in real-time of steels in CSP plants.In the present work, the behaviour of a ferritic-martensitic steel, VM12, in Solar Salt was monitored by EIS. To this end corrosion tests at 580°C were carried out for 1000 h. According to the EIS results, a diffusion-controlled reaction occurred during test, which indicates the formation of a porous corrosion layer. The EIS results also shown a corrosion rate of 50 µm·year−1 after 1000 h of testing. Results obtained by EIS were in agreement with the ones obtained by gravimetric and SEM-EDX analysis. Thus, results showed the possible suitability of EIS for monitoring corrosion processes in real-time of steels in CSP plants.","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"93 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79638818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Retrofitting operating CSP plants with PV to power auxiliary loads – Technical consideration and case study","authors":"S. Bode, A. Cuéllar, I. Perez","doi":"10.1063/1.5117605","DOIUrl":"https://doi.org/10.1063/1.5117605","url":null,"abstract":"In the context of Concentrating Solar Power (CSP) plants, Photovoltaic (PV) augmentation is the process whereby the online parasitic loads (also known as auxiliary loads) of a CSP plant are supplemented by a PV facility located on site. Typically, the cost of energy generated by a PV plant is lower than that generated by a CSP plant and thus, PV augmentation can improve the financial return of CSP projects. While previous work has explored the topic primarily from the point of view of using CSP-PV hybridization on new build CSP or to provide baseload power, this paper focuses specifically on retrofitting existing CSP plants with a PV facility to service only the auxiliary loads. It discusses the technical and design considerations for PV integration in operational CSP plants, as well as the typical regulatory and permitting constraints that are expected to be encountered in offtake agreements. The paper also presents an analytical modelling tool developed by the authors and presents a case study to demonstrate the various design and optimisation strategies, the benefits, and the economic gains which are possible in CSP-PV augmentation.In the context of Concentrating Solar Power (CSP) plants, Photovoltaic (PV) augmentation is the process whereby the online parasitic loads (also known as auxiliary loads) of a CSP plant are supplemented by a PV facility located on site. Typically, the cost of energy generated by a PV plant is lower than that generated by a CSP plant and thus, PV augmentation can improve the financial return of CSP projects. While previous work has explored the topic primarily from the point of view of using CSP-PV hybridization on new build CSP or to provide baseload power, this paper focuses specifically on retrofitting existing CSP plants with a PV facility to service only the auxiliary loads. It discusses the technical and design considerations for PV integration in operational CSP plants, as well as the typical regulatory and permitting constraints that are expected to be encountered in offtake agreements. The paper also presents an analytical modelling tool developed by the authors and presents a case study to demons...","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81165137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New methodology for solar irradiance calculation using Meteosat satellite imagery","authors":"Elsa Tejada Velasco, I. Salbidegoitia","doi":"10.1063/1.5117713","DOIUrl":"https://doi.org/10.1063/1.5117713","url":null,"abstract":"Solar Resource assessment is necessary for concentrated solar power plants development, it is important to choose a suitable location, to ensure the project viability, to improve operation and maintenance procedures and to optimise the energy production. Satellite imagery is a good choice to elaborate this kind of studies due to its historical database that allows to compare many locations and determine reliable meteorological characteristics. The new methodology developed to calculate solar irradiance using MSG imagery enable users to analyse the plant production with high accuracy, MAE 32% lower than previous works, and easily comprehensible presentation of the results.Solar Resource assessment is necessary for concentrated solar power plants development, it is important to choose a suitable location, to ensure the project viability, to improve operation and maintenance procedures and to optimise the energy production. Satellite imagery is a good choice to elaborate this kind of studies due to its historical database that allows to compare many locations and determine reliable meteorological characteristics. The new methodology developed to calculate solar irradiance using MSG imagery enable users to analyse the plant production with high accuracy, MAE 32% lower than previous works, and easily comprehensible presentation of the results.","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84621768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Value contribution of solar plants to the Chilean electric system","authors":"Carlos Benavides, M. Matus, Erick Sierra, R. Sepúlveda, Ana María Ruz, F. Gallardo","doi":"10.1063/1.5117671","DOIUrl":"https://doi.org/10.1063/1.5117671","url":null,"abstract":"The aim of this paper is to quantify the value contribution of solar energy to the Chilean National Electric System (SEN, in Spanish). The assessment is conducted by using long-term planning, hydrothermal coordination and short-term operation models. The results of modeling different expansion and hydrological scenarios, show that photovoltaic (PV) and concentrated solar power (CSP) generation could represent over 50% of the total generation by 2050, reduce the annual greenhouse gases emissions to 12 million tCO2 by 2050, decrease the operational cost of the system, and the potential to foster local investment and job creation. Due to its storage capacity, it is also shown that CSP plants could contribute to frequency control, adequately complementing PV and wind generation in scenarios with high penetration of renewable energy.The aim of this paper is to quantify the value contribution of solar energy to the Chilean National Electric System (SEN, in Spanish). The assessment is conducted by using long-term planning, hydrothermal coordination and short-term operation models. The results of modeling different expansion and hydrological scenarios, show that photovoltaic (PV) and concentrated solar power (CSP) generation could represent over 50% of the total generation by 2050, reduce the annual greenhouse gases emissions to 12 million tCO2 by 2050, decrease the operational cost of the system, and the potential to foster local investment and job creation. Due to its storage capacity, it is also shown that CSP plants could contribute to frequency control, adequately complementing PV and wind generation in scenarios with high penetration of renewable energy.","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73358817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A sodium boiler and phase-change energy storage system","authors":"J. Coventry, John Pye, Apurva Kumar, Siddharth Iyer, Zebedee Kee, W. Lipiński","doi":"10.1063/1.5117588","DOIUrl":"https://doi.org/10.1063/1.5117588","url":null,"abstract":"A novel concentrating solar thermal power system is described, in which a tubular sodium boiler receiver is coupled to a latent heat salt storage system using NaCl. The isothermal liquid-gas phase change of sodium is matched to the isothermal solid-liquid phase change of NaCl, at an appropriate temperature (around 800°C) for a range of industrial process applications, as well as power generation using the Stirling engine. A storage configuration based on direct contact between the sodium and NaCl in shallow trays within a tank is proposed. In the first part of this paper, a detailed dynamic model of the storage system, coupled to simplified models of the receiver and power cycle, was developed to simulate performance over a year. For a case study based on the PS10 heliostat field, a 5.9 MWe system with annual capacity factor of 59.9% was determined to have a levelised cost of energy of 0.23 USD/kWh, using cost assumptions largely based on the 2017 System Advisor Model. Importantly, storage costs, including salt containment in the tank and trays, were a small fraction (8.7%) of total plant capital costs, an indication of the potential feasibility of this form of storage. A key technical challenge for a sodium boiler operating on sun is expected to be boiling stability. Evaporation of the microlayer, the thin layer of fluid formed below a growing bubble, is primarily responsible for bubble growth. The second part of this paper describes initial work to develop fundamental understanding of the causes of boiling instability. Results of modelling indicate the strong dependence of the microlayer heat transfer on the thermophysical properties of the liquid, which may significantly affect bubble characteristics and influence stability.A novel concentrating solar thermal power system is described, in which a tubular sodium boiler receiver is coupled to a latent heat salt storage system using NaCl. The isothermal liquid-gas phase change of sodium is matched to the isothermal solid-liquid phase change of NaCl, at an appropriate temperature (around 800°C) for a range of industrial process applications, as well as power generation using the Stirling engine. A storage configuration based on direct contact between the sodium and NaCl in shallow trays within a tank is proposed. In the first part of this paper, a detailed dynamic model of the storage system, coupled to simplified models of the receiver and power cycle, was developed to simulate performance over a year. For a case study based on the PS10 heliostat field, a 5.9 MWe system with annual capacity factor of 59.9% was determined to have a levelised cost of energy of 0.23 USD/kWh, using cost assumptions largely based on the 2017 System Advisor Model. Importantly, storage costs, includin...","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73391806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The fluidized bed air heat exchanger in a hybrid Brayton-cycle solar power plant","authors":"Shuo Li, Weibin Kong, Huili Zhang, F. Sabatier, R. Ansart, G. Flamant, J. Baeyens","doi":"10.1063/1.5117650","DOIUrl":"https://doi.org/10.1063/1.5117650","url":null,"abstract":"Using group A particle suspensions as heat transfer fluid in concentrated solar power plants leads to higher efficiency and lower costs. Combined cycle power generation becomes possible with e.g. a topping Brayton air turbine cycle and an advanced steam power block as bottoming cycle. This hybrid combined cycle solar tower power plant will be tested on a 3 MWth pilot-scale at the CNRS-Themis solar tower (France) with the receiver, hot powder storage and air Brayton turbine. The suspension will exit the receiver at a nominal outlet temperature of 750-800°C. Hot powders will be stored and will subsequently exchange heat with the turbine air. The outlet temperature of the air heat exchanger (625 to 700 °C) will considerably determine the hybrid operation (reducing the possibly used fossil fuel boost) and the heat exchanger design is of paramount importance. The air heat exchanger will be a baffled cross-flow fluidized bed. Air will be heated in an in-bed finned-tube bundle. Air will be fed at 5.8 bar and∼270°C. The hydrodynamics and heat transfer characteristics of the air heat exchanger were experimentally investigated towards bubble properties and heat trasnfer coefficient. The bed to tube heat transfer coefficient was measured for different pipe geometries at bed temperatures up to 700 °C, exceeding 2 kW/m2K for a twin-bore finned tube but only about 650 W/m²K for the bare tube of equal outside diameter. The heat transfer coefficient from the tube wall to the turbulent air flow inside the tube (∼ 325 W/m2K) determines the design. NEPTUNE_CFD software was used to perform 3D-numerical simulations of the fluidized bed hydrodynamics via an Eulerian n-fluid approach. Simulation and experimental results were in very fair agreement, stressing the capability of mathematical models to predict the behaviour of a cross-flow bubbling fluidized bed.","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73009226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a concrete parabolic trough collector","authors":"D. Krüger, S. Penkert, Jürgen Schnell, N. Janotte, P. Forman, P. Mark, Tobias Stanecker, J. Krüger, Alois Natterer, Matthias Kintscher, R. Dasbach, J. Wette, K. Hennecke, Timo Zippler","doi":"10.1063/1.5117626","DOIUrl":"https://doi.org/10.1063/1.5117626","url":null,"abstract":"Current parabolic trough collector development mainly aims at cost reduction. Within the project ConSol the goal was to reduce material and production costs by using high-performance concrete for the parabola shell itself and also for part of the tracking system. A high amount of manufacturing at the power plant site (“mobile factory”) by delivery of the raw materials and semi-finished products is foreseen, adding value to the local content. Within the project a collector prototype consisting of an extraordinary thin concrete shell was realised based on FEM calculations. The shell is moved via a novel sickle-shaped hill with a newly developed drive system. The collector’s shape was measured by photogrammetry and its optical performance deduced. A part of the ConSol project was dedicated to the improvement of a PVD coated mirror multilayer system on electrochemical polished aluminium strip substrate. With these new layer systems the reflective properties could be increased significantly. Finally, the costs of the system was summarised and cost benchmarks with existing collector technology.Current parabolic trough collector development mainly aims at cost reduction. Within the project ConSol the goal was to reduce material and production costs by using high-performance concrete for the parabola shell itself and also for part of the tracking system. A high amount of manufacturing at the power plant site (“mobile factory”) by delivery of the raw materials and semi-finished products is foreseen, adding value to the local content. Within the project a collector prototype consisting of an extraordinary thin concrete shell was realised based on FEM calculations. The shell is moved via a novel sickle-shaped hill with a newly developed drive system. The collector’s shape was measured by photogrammetry and its optical performance deduced. A part of the ConSol project was dedicated to the improvement of a PVD coated mirror multilayer system on electrochemical polished aluminium strip substrate. With these new layer systems the reflective properties could be increased significantly. Finally, the costs...","PeriodicalId":21790,"journal":{"name":"SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76428211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}