CALCULATION OF HEAT TRANSFER INTENSITY OF GAS FUEL COMBUSTION PRODUCTS

Link for citation: Mrakin A.N., Afanaseva  O.V., Kuleshov O.Yu. Calculation of heat transfer intensity of gas fuel combustion products. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.109-115.  The relevance of the research is determined by the modern trend in the field of thermal power engineering and heat engineering for the transition from traditional gaseous fuel (methane) to the use of hydrogen, methane-hydrogen mixtures, as well as thermochemical conversion gases. Switching to new non-design fuel is justified by considerations of reducing the negative impact on the environment and increasing the thermal efficiency of fuel combustion plants. In this case, the use of fuels with a composition different from the design one will affect the heat transfer processes. The main aim: carrying out a comparative analysis of indicators of the intensity of radiant and convective heat transfer of combustion products of non-design fuels, such as hydrogen, methane-hydrogen mixture and thermochemical conversion gases. As an assumption in the formulation of the problem and objectives of the study, the constancy of the heat release power in the apparatus due to changes in the amount of fuel burned was taken. Objects: heat exchange surface of a fire-tube hot water boiler. Methods: carrying out numerical calculation using traditional approaches to determine the indicators of the intensity of heat transfer in the system «combustion products – metal wall of the pipe of thermal power plants». We also used the relations tested earlier by other authors to calculate the thermophysical parameters of gas mixtures. Results. According to the results of the performed comparative calculations, we can conclude that the transition from the use of conventional fuel (natural gas/methane) to its thermochemical conversion gases under the considered conditions has almost no effect on the integral heat transfer performance. To a greater extent, this transition is caused by changes in the intensity of heat transfer for products of combustion of hydrogen and methane-hydrogen mixture, which will affect the operation of thermal power and heat technological installations. At the same time, it is necessary to conduct additional research on the combustion kinetics of thermochemical methane conversion gases, their thermophysical properties, etc., because the hardware design, type of the catalyst used and operating parameters of the process will affect the composition of obtained synthesis gas

PROBLEM OF USING GROUP DISCUSSION METHOD IN EDUCATIONAL PROCESS UNDER COVID-19 PANDEMIC

The paper considers the problem of using the method of group discussion in the educational process as one of the most important educational problems during the global pandemic Covid-19 in the context of the global lockdown. The group discussion proved a most effective tool in teaching foreign languages. There have been discussed the ways to solve the problem. The effectiveness of the introduction of online technologies into the educational process is stated. The practice of working with students in a distance mode using the Zoom program (March – December 2020) has been submitted. The advantages and disadvantages of the new teaching method are analyzed. The significant advantages of Zoom over other online platforms are the ability to use brainstorming methods, group discussion, case study, and dividing a group within a conference into microgroups. The disadvantages of using Zoom in teaching a foreign language are insignificant and solvable, they are mostly technical problems

Development of a Holographic Waveguide with Thermal Compensation for Augmented Reality Devices

In this research, studies were conducted on the possibility of providing thermal compensation of the information display device circuit based on a holographic waveguide when the wavelength of the radiation source ch as a result of changes in ambient temperature. A variant of implementing the waveguide structure in terms of the geometry of the diffraction gratings arrangement is proposed, its main parameters (grating period, thickness, refractive index) and the dependencies between them affecting the quality of the reproduced image are determined

Experimental Study Results Processing Method for the Marine Diesel Engines Vibration Activity Caused by the Cylinder-Piston Group Operations

The article discusses the method and results of processing statistical data from an experimental study of vibrations in marine diesel engines caused by the operation of cylinder-piston groups. The results of the application of a ranking method for identifying factors that influence vibration in marine diesel engines are presented to determine the most significant ones. A series of experiments were conducted according to special plans to actively implement the random balance method. This helped to establish the correctness of selecting the most significant factors from a variety of factors that influence the process under study. The article presents a mathematical model that enables the calculation of current values and prediction of changes in the most significant indicators, with the clearance between the piston and the cylinder liner being the most important

Development of a Distributed Mathematical Model and Control System for Reducing Pollution Risk in Mineral Water Aquifer Systems

The article is devoted to the problem of the growing need of the mineral water fields’ exploitation process automation. The implementation of control systems and mathematical modeling methods can significantly reduce the fields’ structural integrity violation and pollution of aquifers risks. This research is especially relevant for the fields with difficult conditions of mineral waters occurrence, since the insufficient accuracy of determining the fields’ operating mode parameters can lead to a severe incident. The article describes a distributed mathematical model developed from the geo-filtration equation. Based on this model, a new method for assessing the mutual influence of the fields, the production of which is carried out from one aquifer, is presented. For a more detailed study of the operating mode parameters influence on the object a physical model of the reservoir was developed. The using of Arduino sensors and the developed software allows us to construct a 3D graph of the input action and its response at the different points of the object as temperature distribution. The simulation results make it possible to use the proposed model for the automatic control system synthesis

Image Quality for Near-Eye Display Based on Holographic Waveguides

The paper analyzes the image quality in augmented reality display based on holographic waveguides. Brightness, brightness non-uniformity, image noise, etc., depend on the parameters of the waveguide substrate, the configuration, and the relief shape of diffraction optical elements. The optimal structure of holographic waveguides obtained by analog holography has been studied. The presented recommendations to achieve the best image quality are based on experimental results for different configurations of holographic waveguides

Development of a Distributed Mathematical Model and Control System for Reducing Pollution Risk in Mineral Water Aquifer Systems

The article is devoted to the problem of the growing need of the mineral water fields’ exploitation process automation. The implementation of control systems and mathematical modeling methods can significantly reduce the fields’ structural integrity violation and pollution of aquifers risks. This research is especially relevant for the fields with difficult conditions of mineral waters occurrence, since the insufficient accuracy of determining the fields’ operating mode parameters can lead to a severe incident. The article describes a distributed mathematical model developed from the geo-filtration equation. Based on this model, a new method for assessing the mutual influence of the fields, the production of which is carried out from one aquifer, is presented. For a more detailed study of the operating mode parameters influence on the object a physical model of the reservoir was developed. The using of Arduino sensors and the developed software allows us to construct a 3D graph of the input action and its response at the different points of the object as temperature distribution. The simulation results make it possible to use the proposed model for the automatic control system synthesis

Prospects for Solar Energy Development in Belarus and Tatarstan

This paper discusses the resource, technical, and economic potential of using solar photovoltaic (PV) systems in Belarus and Tatarstan. The considered countries are characterized by poor actinometric conditions and relatively low tariffs for traditional energy resources. At the same time, Belarus is experienced with solar power due to different incentive mechanisms that have been used over the past decade. Moreover, the cost of building solar power plants in Belarus in 2013–2017 was lower than the world average. The cost of electricity production is analyzed depending on the geographical location of sites and the type of owners of solar power plants (i.e., households, businesses and industrial enterprises, electricity producers). Using the data on the cost of photovoltaic systems as presented by IRENA and considering actinometric data for Belarus and Tatarstan, a long-term forecast of PV electricity cost is made. The moments of the break-even points and payback periods are defined for Belarus and Tatarstan

Apparatus for receiving activated coal at mini thermal power plants

Актуальность исследования обусловлена необходимостью разработки технологических решений и аппаратурного оформления производства побочных продуктов на объектах малой распределенной энергетики. Большинство описанных в литературе и представленных на рынке объектов малой энергетики ориентированы на получение тепловой и электрической энергии, т.е. на работу по принципу когенерации. Получение побочных продуктов путем термической переработки твердого топлива позволит оптимизировать систему производства тепловой и электрической энергии на мини-ТЭС, повысить эффективность использования топлива, решить экологические проблемы, а также обеспечить ценными химическими продуктами близлежащие районы и потребителей. Цель: разработать конструкцию и провести расчет аппарата малой мощности для получения активированного угля на мини-ТЭС. Объект:аппарат малой мощности для получения активированного угля путем термической переработки твердого углеродсодержащего сырья в кипящем слое. Методы: гидродинамический расчет неизотермических струй в кипящем слое, тепловой расчет, расчет параметров газораспределительной решетки. Результаты. Разработана конструкция аппарата малой мощности для получения активированного угля на мини-ТЭС. В качестве прототипа установки выбрана конструкция реактора с кипящим слоем. Активатор представляет собой герметичный аппаратс перфорированной газораспределительной решеткой. Для рассматриваемого активатора выбрана наиболее простая перфорированная решетка с вертикальной ориентацией круглых отверстий, вогнутая к центру. Уголь поступает сверху через загрузочный патрубок и распределяется слоем на газораспределительной решетке, подача пара на активацию угля осуществляется в режиме струйного псевдоожижения через форсунки. Горячие газы, в качестве которых используются продукты сгорания топлива, подаются под решетку и приводят слой в псевдоожиженное состояние. Проведен гидродинамический и тепловой расчет аппарата, а именноопределена критическая скорость начала псевдоожижения, степень расширения слоя, расход продуктов сгорания, расчет изотермической струи в псевдоожиженном слое, определены параметры газораспределительной решетки: длина газового факела струи,площадь живого сечения решетки.The relevance of the research is caused by the need to develop technological solutions and hardware design for production of by-pro- ducts at small distributed energy facilities. The majority of small energy objects described in the literature and presented on the market are focused on generation of heat and electrical energy, i.e. on operation of the cogeneration principle. Obtaining by-products by thermal processing of solid fuels allows optimizing the system for production of heat and electricity at mini thermal power plants, improving fuel efficiency, solving environmental problems, and providing valuable chemical products to nearby areas and consumers. The main aim of the research is to develop the design and carry out the calculation of the apparatus of low power to obtain activated carbon at mini thermal power plants. Object: the apparatus of low power for obtaining activated carbon by thermal processing of solid carbon-containing raw materials in the fluidized bed. Methods: hydrodynamic calculation of non-isothermal jets in a fluidized bed, heat calculation, calculation of parameters of the gas distribution grid. Results. The authors have developed the design of a low-power apparatus for producing activated carbon at mini thermal power plant and chose the design of a fluidized bed reactor as a prototype of the installation. The activator is a sealed apparatus with a perforated gas distribution grid. For the considered activator, the simplest perforated grating with a vertical orientation of round holes concave toward the center was chosen. Coal enters from the top through the loading nozzle and is distributed by a layer on the gas distribution grid, steam is supplied to the activation of coal in a jet fluidization mode through the nozzles. Hot gases - the products of fuel combustion - are fed under the grate and bring the layer into a fluidized state. The authors carried out the hydrodynamic and thermal calculations of the apparatus, namely, they determined the critical velocity of the onset of fluidization, the degree of expansion of the bed, the flow rate of combustion products, the calculation of the isothermal jet in the fluidized bed, the parameters of the gas distribution grid: the length of the gas jet, the area of the cross section of the lattice