Proceedings of the Russian higher school Academy of sciences最新文献_第2页

Increasing the thermal conductivity of the phase-change material graphene nanotubes 提高相变材料石墨烯纳米管的导热性

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-12-27 DOI: 10.17212/1727-2769-2022-4-50-65

M. Nizovtsev, V. Letushko, Aleksey N. Sterlyagov

{"title":"Increasing the thermal conductivity of the phase-change material graphene nanotubes","authors":"M. Nizovtsev, V. Letushko, Aleksey N. Sterlyagov","doi":"10.17212/1727-2769-2022-4-50-65","DOIUrl":"https://doi.org/10.17212/1727-2769-2022-4-50-65","url":null,"abstract":"The paper presents the results of experimental studies of the use of graphene nanotubes to increase the thermal conductivity of a phase-changing material. Graphene nanotubes were dispersed in molten paraffin by ultrasonic treatment in an amount of 0.1–0.5 wt.%. The obtained samples of paraffin with graphene nanotubes were examined on a scanning calorimeter. All samples with different content of nanotubes during heating and cooling on the DSC curves had two peaks corresponding to the phase transitions of the main hydrocarbons that are part of the paraffin. The presence of nanotubes in paraffin did not significantly affect the shape of the DSC curves. Expe¬riments with sample heating in a thermostat in terms of the time delay in changing the temperature of the samples indicated an increase in the thermal conductivity of paraffin in the solid state when graphene nanotubes were added to it and a decrease in the liquid state. These effects increased with increasing mass content of nanotubes. The method of stationary heat flow was used to determine the coefficient of thermal conductivity of samples of a phase-changing material with nanotubes. According to the measurement results, the maximum increase in the thermal conductivity of paraffin in the solid state was 22 % at a nanotube concentration of 0.5 wt.%. The thermal conductivity coefficients of various materials with «contrasting» inclusions are compared accor¬ding to the results of calculations and experiments.","PeriodicalId":448354,"journal":{"name":"Proceedings of the Russian higher school Academy of sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114943734","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}

引用次数: 1

Prospects for application of Russian absorption thermal transformers at CCGT-CHPP 俄罗斯吸收式热变压器在CCGT-CHPP的应用前景

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-12-27 DOI: 10.17212/1727-2769-2022-4-39-49

D. Mukhin, Konstantin I. Stepanov, S. L. Elistratov

{"title":"Prospects for application of Russian absorption thermal transformers at CCGT-CHPP","authors":"D. Mukhin, Konstantin I. Stepanov, S. L. Elistratov","doi":"10.17212/1727-2769-2022-4-39-49","DOIUrl":"https://doi.org/10.17212/1727-2769-2022-4-39-49","url":null,"abstract":"The electrical power of power plants based on gas turbines (GT) decreases with an increase in air temperature and, as a result, a decrease in its mass flow at the compressor inlet. This makes it relevant to develop methods for increasing air density by lowering its temperature when wor¬king in hot arid regions and regions with a tropical humid climate. To cool the air, it is proposed to use absorption chillers (LBAC). It is shown that for air cooling in a dry hot climate, it is sufficient to use LBAC with single-stage absorption. For a humid tropical climate, where deeper air cooling is required with a simultaneous decrease in its moisture content, it is proposed to use ABCM with two-stage absorption, which are capable of producing cold at negative temperatures. To do this, it is proposed to introduce an additional evaporation and absorption unit with peri¬pheral equipment into the standard industrial design of the LBAC with single-stage absorption. Comparative energy efficiency of LBAC of standard design and LBAC with two-stage absorption during air cooling at the GT compressor inlet has been evaluated. For such critical facilities for the Russian economy as gas pumping stations using gas turbines, an LBAC unit with two-stage absorption and removal of absorption heat by water-circulating cooling systems based on cooling towers, or using air coolers (drycoolers) with the ability to turn off an additional evaporation unit if necessary, is proposed. and absorption.","PeriodicalId":448354,"journal":{"name":"Proceedings of the Russian higher school Academy of sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130559367","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}

引用次数: 0

Comparative analysis of heat and mass transfer apparatus schemes for indirect-evaporative air cooling 间接蒸发式空气冷却传热传质装置方案的比较分析

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-12-27 DOI: 10.17212/1727-2769-2022-4-18-28

M. Gorbachev, V. Terekhov

引用次数: 0

Study of the evaporation process of aqueous-ethanol solution on a superhydrophilic capillary-porous surface under the conditions of forced convection 强迫对流条件下水-乙醇溶液在超亲水毛细管-多孔表面蒸发过程的研究

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-12-27 DOI: 10.17212/1727-2769-2022-4-7-17

M. Gorbachev, M. Makarov, A. I. Syuzaev, V. Terekhov

{"title":"Study of the evaporation process of aqueous-ethanol solution on a superhydrophilic capillary-porous surface under the conditions of forced convection","authors":"M. Gorbachev, M. Makarov, A. I. Syuzaev, V. Terekhov","doi":"10.17212/1727-2769-2022-4-7-17","DOIUrl":"https://doi.org/10.17212/1727-2769-2022-4-7-17","url":null,"abstract":"In view of the continuous growth of global energy consumption, reduction of non-renewable energy sources, as well as increasing greenhouse gas emissions, it is necessary to introduce pro-mising methods to increase the importance of rational use of energy resources in the industrial, domestic and scientific and technical fields, which will reduce the amount of energy to provide the same level of energy supply of buildings or technological processes in production. This paper considers superhydrophilic capillary-porous surfaces capable of providing heat exchange through phase transition, which is of fundamental importance in evaporative radiators for space applications, heat pipes, as well as in the operation of cooling towers for electricity and heat production in centralized heat supply systems. The study of the heat exchange process with phase transition on the capillary-porous surface was carried out by conducting experiments on evaporation of water-ethanol mixture of different concentration under conditions of forced convection at diffe¬rent orientation of the modified surface in space. The results obtained in this work allow us to judge about the effectiveness of capillary-porous structures in heat exchangers operating on eva¬poration cycles and the Maisotsenko cycle, and are also applicable to further study of heat and mass transfer processes occurring on superhydrophilic capillary-porous surfaces.","PeriodicalId":448354,"journal":{"name":"Proceedings of the Russian higher school Academy of sciences","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124390799","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}

引用次数: 0

Calculation of the structural parameters of a multi-cylinder thermal generator based on the Couette-Taylor flow 基于Couette-Taylor流的多缸热力发生器结构参数计算

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-12-27 DOI: 10.17212/1727-2769-2022-4-29-38

N. Miskiv, A. D. Nazarov, A. Serov, V. N. Mamonov

{"title":"Calculation of the structural parameters of a multi-cylinder thermal generator based on the Couette-Taylor flow","authors":"N. Miskiv, A. D. Nazarov, A. Serov, V. N. Mamonov","doi":"10.17212/1727-2769-2022-4-29-38","DOIUrl":"https://doi.org/10.17212/1727-2769-2022-4-29-38","url":null,"abstract":"Direct conversion of wind energy into heat is a relevant direction for the development of alternative heat power engineering. The paper considers an efficient wind heat generator that consists of two rotors nested in each other's annular gaps and forming a system of cylindrical coaxial annular channels filled with a viscous working fluid. Depending on the properties of the working fluid, the velocity of the rotors, the number of annular channels and their geometry, there are combinations of parameters for the optimal design of the heat generator. The proposed method for selecting the design parameters of coaxial rotors makes it possible to directly select the optimal design of rotors for a given power of the heat generator and the properties of a viscous working fluid. The design of the multi-cylinder system of the heat generator, which uses the annular Couette–Taylor flow, is presented in the form of an equivalent single annular gap, which made it possible to generalize the results of investigations carried out with different working fluids under various conditions, in the form of a single dependence of the dimensionless power of the heat generator on the number Reynolds. The obtained dependence is well approximated by a linear function in the experimentally studied range of Reynolds numbers. An algorithm for calculating the geometric design parameters of a multi-cylinder annular system is proposed. As an example, calculations of the structural dimensions of nine variants of heat generators for three power values are given: 10 kW, 20 kW and 50 kW.","PeriodicalId":448354,"journal":{"name":"Proceedings of the Russian higher school Academy of sciences","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124974772","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}

引用次数: 0

Superheavy elements 超重元素

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-09-29 DOI: 10.17212/1727-2769-2022-3-25-30

Aleksey S. Yatsenko

引用次数: 0

Experimental confirmation of the concept of the photon spatial switch based on off-axis zone plate in the millimeter range 基于离轴带板的毫米级光子空间开关概念的实验验证

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-09-29 DOI: 10.17212/1727-2769-2022-3-42-50

A. G. Paulish, O. Minin, I. Minin

引用次数: 0

Two-point model of rotating blades 旋转叶片的两点模型

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-09-29 DOI: 10.17212/1727-2769-2022-3-31-41

S. V. Zhitnik, M. Stepanov

引用次数: 0

The effect of longitudinal and transverse pitch ratio on the flow characteristics of staggered drop-shaped tubes bundle 纵向和横向节距比对交错水滴形管束流动特性的影响

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-09-29 DOI: 10.17212/1727-2769-2022-3-5-24

R. Deeb

引用次数: 0

Stepless control of the modulation index of a three-phase drive inverter in the flat-top’ mode 平顶模式下三相驱动逆变器调制指标的无级控制

Proceedings of the Russian higher school Academy of sciences Pub Date : 2022-06-30 DOI: 10.17212/1727-2769-2022-2-7-19

A. Kromm, Gennady M. Simakov, Andrey E. Gusev

{"title":"Stepless control of the modulation index of a three-phase drive inverter in the flat-top’ mode","authors":"A. Kromm, Gennady M. Simakov, Andrey E. Gusev","doi":"10.17212/1727-2769-2022-2-7-19","DOIUrl":"https://doi.org/10.17212/1727-2769-2022-2-7-19","url":null,"abstract":"The article discusses one of the ways of stepless overmodulation in a semiconductor three-phase voltage inverter implemented according to the B6 scheme. In the review part of the article, the features of the PWM and overmodulation (“flat-top”) modes are briefly considered. The formation of the maximum possible values of the output voltage of the converter is possible due to the maximum values of the modulation index and the voltage inverter coefficient. It is shown that a variable-modulation index in the \"flat-top\" mode has a number of significant advantages over a fixed one, formed, for example, by \"mixing\" the PWM reference signal with additional harmonic signals. The geometric interpretation of the positions of the inverter output voltage vectors on the plane and their connection with the PWM reference signal made it possible to synthesize a high-precision (basic) non-linear characteristic in the inverter reference voltage path and to form a linear stepless control law for the inverter output voltage when the “flat-top” of the specified voltage coefficient is activated. The results of comparison of the basic variant of converter output voltage control with a simpler one obtained by approximating the basic equations using numerical methods of mathematics and computer simulation are presented. The absolute error of the modulation index in the case of approximation is no more than one percent in the entire \"flat-top\" range. The hodographs of the output voltage of the inverter in the X-Y axes are given for three different coefficients of the converter during the transition from PWM to \"flat-top\". The advantages of the method include the simplicity of its implementation in a new or existing space-vector PWM, the implementation of which is carried out exclusively by a software product. This aspect makes this method particularly attractive in low budget drives.","PeriodicalId":448354,"journal":{"name":"Proceedings of the Russian higher school Academy of sciences","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116929591","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}

引用次数: 0