Thermal Engineering最新文献

{"title":"Investigation into Operation of Energy-Intensive Heat Exchangers with Many Plates","authors":"A. E. Baranov,&nbsp;A. E. Belov,&nbsp;D. N. Il’mov,&nbsp;V. A. Mavrov,&nbsp;A. S. Skorokhodov,&nbsp;N. I. Filatov","doi":"10.1134/S0040601524060028","DOIUrl":"10.1134/S0040601524060028","url":null,"abstract":"<p>Heat exchangers in a gas turbine circuit for advanced space power facilities are innovative developments in the field of elaboration of heat exchangers meeting a set of technical and operating requirements. A design of a heat-transfer matrix consisting of a set of biconvex stamped plates with a specific surface relief is proposed. It enables construction of heat exchangers meeting the requirements for strength, stiffness, weight, and size under the specified operating conditions. The results of testing of heat exchangers made of 288 and 450 plates are presented. A nonuniformity of the coolant distribution among heat-transfer panels was found. Under the same operating conditions, it makes the thermal efficiency of a heat exchanger made of 450 plates lower than that of a heat exchanger made of 288 plates. Based on the analysis of test results, a mathematical model has been developed for the thermal and gas-dynamic design calculation of a heat exchanger with an arbitrary number of plates, which takes into account the effect of nonuniformity of the coolant flow through the channels between the plates. The calculation calls for determination of a temperature distribution along the length of each channel considering variable thermophysical properties of the coolant. For the mathematical model, a dimensionless dependence of the resistance coefficient and the Nusselt number on the Reynolds number was found in the Reynolds number range from 500 to 2000. Universal dependences enable simulation in both hot coolant paths consisting of identical interplate channels and cold coolant paths consisting of the same complete and half channels. The correlations for the hydraulic resistance coefficient and the Nusselt number versus the Reynolds number agree well with the known dependences obtained for corrugated heat-transfer surfaces of the same class. The mathematical model has been verified against experimental data. The effect of the scheme of connection of heat exchangers with different number of plates to a gas circuit is examined. The connection schemes are analyzed, and one of them is recommended as the most suitable for practice.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 6","pages":"499 - 512"},"PeriodicalIF":0.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550133","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":"Is SNPP Development a Fashion or an Essential Necessity? [Comment on the Article by V.O. Kindra, I.A. Maksimov, I.I. Komarov, S.K. Osipov, and O.V. Zlyvko “Small Power Nuclear Plants: Technical Level and Prospects for Commercialization (Review)”]","authors":"S. L. Solov’ev","doi":"10.1134/S0040601524050082","DOIUrl":"10.1134/S0040601524050082","url":null,"abstract":"<p>This report examines the issue of economic feasibility of constructing small nuclear power plants (SNPPs). The preparation of this commentary is due to a number of controversial theses presented in the article by V.O. Kindra, I.A. Maksimov, I.I. Komarov, S.K. Osipov, and O.V. Zlyvko “Small-Power Nuclear Power Plants: Technical Level and Prospects for Commercialization (Review)”, published in the journal <i>Teploenergetika</i> no. 4, 2024. The article notes the need to use new circuit solutions and working fluids for SNPPs. However, an analysis of the prerequisites for the creation of SNPPs allows for the conclusion that the use of complex thermal cycle circuits for such plants is inappropriate. The article rightly notes that SNPPs can only be competitive in remote areas that are difficult to access for the import of fossil fuels. But the inaccessibility of the territories is a determining and largely limiting factor for the construction and operation of SNPPs themselves on these sites.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 6","pages":"544 - 545"},"PeriodicalIF":0.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550137","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":"Static Strength Assessment of Turbine Blades in High-Capacity Power Units","authors":"A. N. Arkhipov,&nbsp;I. V. Puchkov,&nbsp;Yu. A. Ravikovich,&nbsp;O. V. Romanova,&nbsp;A. A. Ivanovskii","doi":"10.1134/S0040601524060016","DOIUrl":"10.1134/S0040601524060016","url":null,"abstract":"<p>The article considers assessment methods and criteria of damage inflicted to turbine blades under the effect of static loads in carrying out 3D structural analyses of modern foreign and domestically produced high-capacity power units. Factors that should be considered in performing strength and lifetime analyses of the rotor blades of high-capacity turbines when subjected to short- and long-term static loading are pointed out. The article also describes 3D techniques for carrying out elastoplastic assessment of short-term static strength using a procedure for determining the limit rotation speed to blade fracture, airfoil residual displacements and strains, shank ultimate strength and displacement, root tearing-off, shear, flexural strength, etc. The article presents mutually complementary techniques for determining the bearing capacity as well as global and local long-term strength with using cumulative strain predictions by creep curves. Criteria used in different lifetime assessment methods are described, including those applied at different design stages and in using thermal protection coatings. Cases are considered in which creep strains are determined in the absence of data on creep curves by carrying out elastoplastic analyses by isochronous curves and lifetime analysis using the Larson–Miller curves. The need to take multiaxiality into account in estimating local creep in places of stress concentration is shown, and the applicability limits and criteria of such assessment that make it possible to increase the predicted lifetime by up to two times are described. Examples of tensile and compressive stress relaxation in estimating cumulative creep strain are given. Matters of creep interaction with other types of damage, including high-cycle and low-cycle (thermal cycling) fatigue, and various turbine loading kinds are considered.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 6","pages":"523 - 533"},"PeriodicalIF":0.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550135","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":"Application Research of Differential Evolution Algoritm in Resistance Coefficient Identification of Heating Pipeline","authors":"Bingwen Zhao,&nbsp;Ruxue Yan,&nbsp;Yu Jin,&nbsp;Hanyu Zheng","doi":"10.1134/S0040601524060065","DOIUrl":"10.1134/S0040601524060065","url":null,"abstract":"<p>The district heating system is an important heating mode in the northern cities of China. In recent years, the scale of the district heating system is expanding day by day, the pipe network structure is more and more complex. The problem of hydraulic imbalance of the pipe network is gradually emerging, therefore, it is urgent to establish an accurate and perfect hydraulic simulation model of heating network to assist operation management. Pipe network simulation modeling is one of the important prerequisites to solve the hydraulic imbalance problem of heating pipe network. However, with the increase of service time, the actual resistance coefficient of heating network becomes difficult to obtain, which is one of the key reasons for the low accuracy of pipe network simulation model. In order to overcome this difficulty, this paper proposes to use the resistance coefficient identification model based on the differential evolution algorithm (DEA) to identify the resistance coefficient of the heating pipe network. Based on graph theory, network matrix and the law of conservation of mass, the hydraulic model of the heating pipe network is built, and the nodal pressure method is used to solve the model. On the basis of comprehensive consideration of the mainstream intelligent algorithm, the differential evolution method is selected as the algorithm to identify the resistance coefficient of pipeline. In order to verify the identification effect, the feasibility of the model was verified by calculating the data of three different operating conditions of the practical engineering named “K district heating system”. The results demonstrated that the relative errors of the identified resistance coefficients are all within 10, and 98% of the identified values are less than 5%.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 6","pages":"534 - 543"},"PeriodicalIF":0.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550136","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":"Simulation of Film Condensation from Moving Vapor of Refrigerant-21 on a Horizontal Tube Bundle Using the VOF Method","authors":"K. B. Minko,&nbsp;V. I. Artemov,&nbsp;A. A. Klement’ev","doi":"10.1134/S004060152406003X","DOIUrl":"10.1134/S004060152406003X","url":null,"abstract":"<p>Considerable progress has been made by now in developing mathematical models, algorithms, and available computational tools for simulating heat and mass transfer processes. Advanced approaches yield detailed information on various characteristics of mass transfer in two-phase fluids, in particular during film condensation of vapors. Models developed by various teams are implemented in CFD-codes (ANSYS Fluent, OpenFOAM, Star-CCM+, etc.). To check existing models and select the best one, cross-verification of models and algorithms implemented in various CFD codes and their verification against available and reliable experimental data are needed. In this paper, cross-verification of the VOF (Volume of Fluid) model and the algorithms implemented in the author’s ANES code was carried out against the problem of vapor condensation on a single tube. The calculations were performed using the ANES and ANSYS Fluent CFD-codes. The predictions by the ANSYS Fluent code have been demonstrated to depend on the settings of the algorithms for solving the conservation equation for the liquid volume fraction. Recommendations are presented for setting this code to obtain better agreement of the predictions with experimental data and theoretical relationships. The ANSYS Fluent code was used for two-dimensional simulation of refrigerant-21 condensation in a small tube bundle. Characteristics of the tube bundle (bank) were equal to those of the tube bundle used in the experimental setup of the Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences (tube diameter <img> = 16 mm, transverse tube bundle pitch <span>({{S}_{1}})</span> = 26 mm, longitudinal tube bundle pitch <span>({{S}_{2}})</span> = 15 mm). Condensation of saturated vapor having a saturation temperature of <span>({{T}_{{sat}}})</span> = 333.15 K and arriving at the tube bundle at a velocity of up to 1.2 m/s was studied. The predictions demonstrate qualitative and quantitative agreement with the experimental data.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 6","pages":"482 - 498"},"PeriodicalIF":0.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141552906","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":"Estimating the Influence of Compressor Blade Erosion Wear on the Compressor’s Integral and Local Characteristics","authors":"V. L. Blinov,&nbsp;I. S. Zubkov,&nbsp;G. A. Deryabin","doi":"10.1134/S0040601524050033","DOIUrl":"10.1134/S0040601524050033","url":null,"abstract":"<p>Assessment, monitoring, and prediction of the technical condition of gas turbine unit (GTU) assemblies and components are among the key matters that have to be dealt with during the operation of GTUs. In this connection, various prediction systems that use statistical, experimental, and calculated data on the change in the axial compressor (AC) characteristics resulting from the occurring erosion are becoming of great demand. The article describes an approach to the development of models of erosively worn blades on the basis of freely accessible statistical data on the failures of units as a consequence of a blade compressor’s erosion. The article also proposes a body of mathematics for specifying the blade wear degree, introducing the change in the eroded profile chord, and considering the wear nonuniformity along the blade height. The statement of the problem of numerically studying how the erosion degree and pattern affect the compressor stage performance parameters is described. The outcomes from intermediate studies on comparing different geometrical models of erosion are presented along with assessment of their applicability for flow computations in elaborating a prediction model. The results of computations of a transonic compressor stage have been obtained for different erosion wear degrees of its blading in a wide range of operation modes, and the revealed degradation pattern of the stage integral and local characteristics is analyzed. It has been found from analyzing various erosion wear degrees for the stage considered that, if there is an erosion wear, the compressor pressure ratio may drop by up to 3.31%, the ratio of temperatures by up to 1.55%, the adiabatic efficiency by up to 1.15% (abs.), and mass flowrate at the stage choke line up to 1.26%. With decreasing the rotor rotation frequency, the wear influence decreases, and the change in integral characteristics do not exceed 0.10% for the isodrome (a constant rotation frequency line) 70%. The article briefly outlines possible methods for analyzing the results for constructing the correlations between the erosion wear degree and the change in the compressor integral characteristics and also promising lines for development of studies.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 5","pages":"440 - 451"},"PeriodicalIF":0.9,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141144550","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":"Validation of the STEG Code against Experimental Data on Hydrodynamics of a Horizontal Steam Generator","authors":"H. Abdi,&nbsp;N. Ouregani Jafari,&nbsp;V. I. Melikhov,&nbsp;O. I. Melikhov","doi":"10.1134/S004060152405001X","DOIUrl":"10.1134/S004060152405001X","url":null,"abstract":"<p>A numerical analysis of the experiments addressed to studies of hydrodynamic processes in a horizontal steam generator has been performed using the STEG (STEam Generator) code. The main components of the experimental model include a staggered tube bundle, a submerged perforated sheet (SPS) with baffles, and a downcomer. An air–water mixture was used as a two-phase fluid. The working fluid flow in the model was driven by natural circulation induced by air supply to the lower, middle, and upper sections of the tube bundle. The gas void fraction was measured by the γ-radiography method. In addition, pressure drops along the height of the tube bundle and water levels in the model and above SPS were also measured. Each experiment was performed at a prescribed air load on the evaporation surface and water level in the model. The STEG code was developed at the Department of Nuclear Power Plants of NRU MPEI to model thermohydraulic processes in a horizontal steam generator. The mathematical model is based on a two-fluid approach to the description of a two-phase flow using balance mass, momentum, and energy conservation equations and semiempirical closing correlations for interfacial interactions and interactions with various surrounding structures (tube bundle, walls, etc.). The STEG code was used to perform calculations for nine experimental regimes differing in the perforation ratio of the submerged perforated sheet and the supplied air flowrate. The qualitative regularities of the two-phase air–water mixture circulation in the model of a horizontal steam generator and the effect of experimental values of the main parameters on the circulation have been established. Quantitative results of comparison of the predictions with the experiment demonstrate their good agreement since the relative errors in the predicted air void fractions and pressure drops do not exceed 10%.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 5","pages":"400 - 411"},"PeriodicalIF":0.9,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141131563","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":"Study of Heating and Evaporation of Rotating Graphene Nanofluid under the Influence of Solar Radiation","authors":"K. T. Chan,&nbsp;A. S. Dmitriev,&nbsp;I. A. Mikhailova,&nbsp;P. G. Makarov","doi":"10.1134/S0040601524050045","DOIUrl":"10.1134/S0040601524050045","url":null,"abstract":"<p>Conversion of solar radiation into steam is presently one of the trends in “green” energy (solar thermal energy), ecology, and clean water production. For the first time, a study of the heating and evaporation of a rotating graphene nanofluid under the influence of radiation from a solar simulator was carried out. The influence of various factors on these processes, including the direction of irradiation, graphene concentration, and liquid rotation speed, is considered. It has been shown that the evaporation rate significantly depends on the graphene concentration and the method of irradiation of the samples. When samples are irradiated from the side, as the graphene concentration increases, the average evaporation rate increases and reaches a maximum value and then decreases. When samples are irradiated from above and the liquid–air interface is in direct contact with the incident radiation, only a decrease in the evaporation rate is observed as the graphene concentration increases. In this case, heating of graphene also depends on the method of irradiating the sample. When in direct contact with radiation, graphene is heated to a high temperature, while in the bulk it is heated less efficiently than the base liquid (distilled water). It has been shown that the rate of evaporation from the surface of a rotating graphene nanofluid and the temperature of its volume significantly depend on the rotation speed. Of all the samples studied, a graphene nanofluid with a volume concentration of 0.5% is heated most efficiently. The use of thermal insulation can improve heating by approximately 5%. An analytical calculation of the profile of the interfacial surface is presented and its area is determined at different speeds of rotation of the liquid. Some effects that arise during the rotation of a graphene nanofluid and their influence on the parameters of hydrodynamics and heat and mass transfer, which is important for fundamental and applied energy problems, have been identified.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 5","pages":"452 - 464"},"PeriodicalIF":0.9,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141139447","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":"Coolant Hydrodynamics at the Inlet to the FA of the RITM-Type Reactor of a Small Nuclear Power Plant","authors":"S. M. Dmitriev,&nbsp;T. D. Demkina,&nbsp;A. A. Dobrov,&nbsp;D. V. Doronkov,&nbsp;D. S. Doronkova,&nbsp;A. N. Pronin,&nbsp;A. V. Ryazanov","doi":"10.1134/S0040601524050057","DOIUrl":"10.1134/S0040601524050057","url":null,"abstract":"<p>The results of an experimental study into the features of the process of coolant flow formation in the inlet section of the fuel assembly (FA) of the core of a RITM-type reactor of a small nuclear power plant (SNPP) are presented. The purpose of the work is to evaluate the influence of different design elements of the inlet section on the formation of coolant flow. To achieve this goal, a series of experiments was completed on a research aerodynamic stand with an air working environment using a large-scale experimental model, including structural elements of the FA inlet section from the throttle orifice to the fuel rod fastening unit to the diffuser, as well as a fragment of the fuel rod bundle between the absorber and spacer grids. The studies were carried out using the pneumometric method and the method of injection of a contrast admixture in several sections along the length of the model. Measurements were made over the entire cross section of the model. Features of the coolant flow are visualized by cartograms of the axial flow velocity of the working medium and the distribution of admixture in the cross section of the model. The research results were used by specialists from the design and calculation departments of OKBM Afrikantov to substantiate engineering solutions when designing new cores of RITM reactors. The results of the experiments were collected into a database and used in the validation of the LOGOS CFD computer program created by employees of the All-Russian Research Institute of Experimental Physics and the Institute for Theoretical and Mathematical Physics of Moscow State University as analogues of foreign computer programs of the same class, which include ANSYS, Star CCM, etc. Experimental data were also used when validating one-dimensional thermal-hydraulic codes used at OKBM Afrikantov in substantiating the thermal reliability of reactor cores. The thermohydraulic code CANAL is also included in this class of computer programs.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 5","pages":"375 - 390"},"PeriodicalIF":0.9,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141144441","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":"Comprehensive Development of Brines of the Berikei Geothermal Field","authors":"A. B. Alkhasov,&nbsp;D. A. Alkhasova","doi":"10.1134/S0040601524050021","DOIUrl":"10.1134/S0040601524050021","url":null,"abstract":"<p>It has been shown that complex processing of hydrothermal brines from the Berikei geothermal field can be highly effective. The development of the deposit’s resources can be carried out in two stages. At the first stage, it is proposed to organize the production of chemical compounds based on self-flowing brines. After developing the technology for extracting chemical components from brine, it is recommended to move on to the second stage: implementing an integrated technology for utilizing thermal energy with the subsequent extraction of chemical components from the cooled brine. This technique allows one to use all the resources of the field. The thermal energy of the geothermal brine is recovered in a greenhouse and a geothermal steam-gas power plant (GSGP), which includes units of a binary geothermal power plant (GeoPP) and a gas turbine power plant (GTPP). In a binary GeoPP, the low-boiling working fluid is heated to a higher temperature by removing heat from the geothermal brine. Further heating of the working fluid to the evaporation temperature and its evaporation and overheating are carried out by the heat of the GTPP exhaust gases. The construction of a GSGP will allow for uninterrupted and autonomous supply of electricity to the entire complex. The development of all hydrothermal resources of the Berikei deposit will make it possible to annually obtain 2000 t of lithium carbonate and, thereby, provide a significant part of the needs of Russian industry as well as produce more than 580 000 t of table salt, which will solve the problem of import substitution of this product.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":"71 5","pages":"465 - 469"},"PeriodicalIF":0.9,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141145052","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}