Bolotin, Kirill Evgenyevich

Telicko J., Bolotin K.

Abstract Buildings consume about 40 % of all energy. Ventilation plays a significant role in both the energy consumption of buildings and the comfort of occupants. To achieve energy efficiency and comfort, smarter ventilation control algorithms can be employed, such as those with feedback based on CO2 levels. Furthermore, by knowing the current number of people in a space, ventilation can theoretically be adjusted to maintain a constant CO2 level without wasting energy when people are not present. An additional benefit of such control could arise due to occupants’ habits. For example, if a person senses elevated CO2 levels, even if the ventilation system has started operating more intense, they might choose to open a window, potentially compromising energy efficiency. Therefore, if the control algorithm were to maintain a constant CO2 level, occupants may be less likely to open windows. In our work, we explore a model in combination with a custom monitoring system based on computer vision to implement such control. The monitoring system combines outside and inside CO2 sensors with precise people counting based on computer vision to provide data to the model. The model relies on the mass balance equation for CO2 and considers the historical data of the number of occupants and their activities to estimate the overall CO2 generation in indoor spaces. The results suggest that the model can effectively forecast CO2 dynamics with an absolute deviation of 40 ppm. However, it was observed that the analysis of the actual air exchange level could be compromised by several factors.

Bolotin K., Jakovics A., Telicko J.

Abstract Paper is devoted to the development and verification of a tool for modeling and designing radiant-panel heating and cooling systems. Source of radiation is capillary mats, which consist of tubes through which water flows with a temperature of 18°C to 32°C, depending on the operating mode. The tool is an analytical model that takes into account the radiation from capillary mats located on the ceiling and walls, the mutual radiation of all surfaces in the room, including doors and windows, simplified convection, as well as third-party sources of thermal energy, such as the sun, electronics and people. The model was compared with a similar numerical model created in Comsol Multiphysics, and also verified by experimental data.

Bolotin K., Brazhnik D.

Paper is devoted to study of the possibility of using a bottom induction stirrer with a rotating electromagnetic field for a force on melt of precious metals in a graphite crucible of an induction crucible furnace. The option of liquid metal stirring after melting is completed to achieve temperature uniformity was investigated. Numerical simulation of three depended problems was carried out: electromagnetic, hydrodynamic, and heat transfer in liquids. The optimization of supply current frequency magnitude was carried out by the Nelder-Mead method; the difference between the maximum and minimum temperatures in the melt volume four seconds after the start of stirring was chosen as the objective function, its minimization was achieved. Range of optimal frequencies of the supply current from 250 to 260 Hz was determined. The most effective frequency is f = 256.2 Hz, with it the temperature difference was ΔT = 8.6 °C. At the next stage, the process of mixing the metal during its melting will be considered.

Evgeny S., Sokolov I., Bolotin K., Zakharov V.

Purpose The purpose of this paper is to determine how the shape of the container affects the efficiency of a traveling magnetic field (TMF) stirring. Design/methodology/approach The modeling approach is based on finite element software Comsol which includes harmonic electromagnetic (EM), transient CFD and particle tracing modules. For evaluating efficiency of stirring the particle, homogenization parameter is used. Findings It has been determined that the use of an elliptical cylinder-shaped vessel allows better heat removal from the side surface and, at the same time, the stirring efficiency does not drop significantly. Practical implications The results of the work can be used in the design of EM stirring installations in which exothermic reactions occur. Originality/value The transient simulation of particle transport in a TMF-driven melt flow gives the opportunity to estimate the efficiency of stirring process in different vessel shapes.

Bolotin K., Shvidkii E.L., Sokolov I., Bychkov S.A.

Purpose The purpose of this paper is to search optimal shape of soft magnetic composite-based inserts used to compensate the working gap between the liquid metal and the induction stirrer in metallurgical installations. Design/methodology/approach The study was based on numerical simulation of electromagnetic processes in frequency domain. To optimize inserts shape, the Nelder–Mead method was used. The maximum of integral electrodynamic force along x-axis was chosen as the objective function. All simulations were performed in finite element software package Comsol Multiphysics. Findings Optimal inserts shape was determined, at which the value of integral electrodynamic force along x-axis increased by 20% from 692  to 792 N. Originality/value Magnetic concentrators based on soft magnetic composite materials have long been used in high-frequency systems; at the same time, their use in low-frequency systems has not been previously considered in detail. The study of the shape effect of concentrators on the effectiveness of electromagnetic field in a liquid metal in a three-dimensional formulation was carried out for the first time.

Brazhnik D.S., Bolotin K.E.

Present paper is devote to study of different approaches to taking into account the distribution of Joule heat in the numerical simulation of the heating of a copper load in a graphite crucible of an induction furnace. Two options were considered and compared: the electromagnetic and heat transfer problems with temperature feedback, solved in the time domain, and only the thermal problem solved in the time domain, the distribution of the released heat to which was transferred from the frequency domain electromagnetic problem. Main objective of this study is to reduce the estimated time due to the correct selection of assumptions.

Bolotin K.E., Brazhnik D.S.

Paper presents results of numerical simulation of an induction stirrer with a traveling magnetic field, the magnetic core of which is made of a iron-based soft magnetic composite. Material magnetic properties were calculated by the analytical method. Numerical model includes an frequency domain electromagnetic problem, which takes into account the magnetization curve of magnetic core material. The integral tangential Lorentz force was chosen as the estimation parameter. A comparison of the calculation results for magnetic cores made of soft magnetic composite and electrical steel was made.

Sokolov I., Shvydkiy E., Losev G., Bolotin K., Bychkov S.

Abstract In modern times, exposure to a liquid metal by a travelling magnetic field is widely applied. There are laboratory studies on the processes of stirring and crystallization under the action of a traveling magnetic field. However, in the majority of studies it is assumed that the inductor power supply of the linear induction machine is carried out by a symmetrical three-phase system of currents with an equal phase shift, which, in some cases, is not quite correct. To approximate the model to real operating conditions, a numerical simulation of the magnetic field and the flow of liquid metal was carried out when supplied from a power source of symmetric three-phase voltage. The distortion of magnetic field, which, in turn, causes an nonuniform distribution of forces and the flow of a liquid metal, is shown. Evaluation of asymmetrical effect on the liquid metal flow was carried out by means of finite element method. That effect is caused by different coefficients of mutual coils induction of the linear induction machine, which is confirmed by experimental data.

K. Bolotin, E. Shvydkiy, I. Sokolov

E. Shvydkiy, K. Bolotin, I. Sokolov

Sokolov I.V., Bolotin K.E., Sarapulov S.F., Kravtsov A.A.

Volume heating used during silicon purifying permit uniformly temperature distribution at all bowl. Forced stirring with quartz devices is associated with high process failure and low efficiency. To intensify the process, it is proposed to use electromagnetic stirring by a traveling magnetic field. Optimal shape design of stirrer can be obtained by a multiobjective optimization method based on gradient descent to reduce primary weight and stirring time, simultaneously. Objective function is defined from magnetohydrodynamic problem considered in this article. Also, different version of magnetic core is examined. This coupled-field problem is decoupled to separated magnetic, hydrodynamic and thermal problems and analyzed by means of finite element method, while the optimal design problem is solved by gradient-based algorithm and best solution is chosen.

Bolotin K.E., Sokolov I.V., Bychkov S.A.

Shape optimization occupies an important place in the development of MHD-stirrer for liquid metal, allowing to reduce economic and time costs. For all importance and relevance, there is still no unequivocal opinion as to which optimality criterion should be chosen: integral electromechanical force, integral melt velocity or time of technological process, for example, equalizing temperature in the melt volume. Present paper is devoted to comparing results of magnetic core optimization for MHD-stirrer with a traveling EM field for listed optimality criteria. As a parameter, by which efficiency of obtained result was evaluated, the time taken to equalize temperature in the melt volume was chosen.

Bolotin K.E., Frizen V.E., Sokolov I.F., Bychkov S.A.

Paper presents results of numerical simulation of the induction stirrer for 12-ton metallurgical aggregate for liquid aluminum. A comparison between several designs of stirrer was made. Influence of stirrer position relative to metal was considered. In addition, a study of the effect of adding special high temperature magnetodielectric inserts to the lining was made. Based on the results obtained, the most energy effective design of the induction stirrer.

Bolotin K.E., Frizen V.E., Shvidkiy E.L.

The article deals with numerical modelling of a bottom electromagnetic stirrer with a rotating field. The influence of the magnitude of the current, working gap and frequency was considered. Three-dimensional numerical modelling of electromagnetic, hydrodynamic turbulent and temperature fields using the commercial software package COMSOL Multiphysics.

Smolyanov I., Frizen V., Bolotin K., Ulrych B.

This paper considers the physical experiments of a laboratory induction heating plant with various forms of billet. The obtained results of numerical simulation are verified with the help of a physical experiment. The main method of obtaining physical thermal and electromagnetic characteristics is the finite element method implemented in the computer environment of Comsol Multiphysics. The magnetic problem is solved in a quasistatic formulation. Thermal processes are analyzed in stationary and dynamic modes. The major purpose of the paper is research of energy and technology feature for different form of charge. The main conclusions are given on the possibility of improving the energy parameters depending on the technology.

Di Barba P., Ghafoorinejad A., Mognaschi M.E., Dughiero F., Forzan M., Sieni E.

In this paper, a multi-physics case study belonging to the class of induction heating problem is considered. Finite Element Analysis is used to evaluate the temperature along a line on a graphite disk heated by two power inductors. In order to build a surrogate field model of the device, i.e., to compute the temperature profile on the disk, given the amplitudes and frequencies of the supply currents, three methods have been used (Support Vector Regression (SVR), fully connected Neural Network (NN) and Gaussian Process Regression (GPR)). In turn, to solve the inverse problem, i.e., to identify frequencies and currents of the two coils, given a prescribed temperature profile, two approaches have been implemented. The former is an optimization approach based on a multi-objective formulation, solved by means of the NSGA-II algorithm; the latter is a two-step procedure, based on fully connected Deep Neural Networks (DNNs), solving an optimal design problem first and, subsequently, an optimal control problem.

Bicakci S., Citak H., Gunes H., Coramik M., Ege Y.

Stolzke T., Schwarz J., März M.

Uskov V.A., Solokhnenko V.V., Burtsev D.S., Ponomarev A.A., Ogneva A.D.

This article considers the intensity of a magnetic field as one of the key parameters of induction heating, which is frequently used in machine engineering. Following the analysis of papers by leading researchers, the authors of this article developed a mathematical model to calculate magnetic field intensity at any point within a random cylindrical inductor by using the superposition principle and the Biot-Savart-Laplace law. This mathematical model contains elliptical integrals of the first and second types and do not have an analytical solution, but can be solved by numerical methods. In this case the mathematical model was implemented with publicly available and versatile software: MS Office (Excel) using the built-in Visual Basic for Applications (VBA) programming language by using the Simpson method (method of parabolas). It can be used for subsequent induction research, improving induction plant parameter calculation procedures, and as the basis for the development of specialized software for induction heating system modeling and design.

Shishkin A.V., Yavorovsky Y.V., Zhigulina E.V.

Kamaev D.A., Frizen V.E., Lusgin V.I.

Nie J., Wang K., Chao X., Li J., Song K., Lv L.

To adjust the flow rate of liquid in the pipeline in real-time in the process of crop drip irrigation, to achieve sustainable agricultural irrigation. This paper designs and develops a kind of liquid speed-regulating device for drip irrigation based on traveling wave magnetic field. This paper aims to use the electromagnetic driving force generated by the traveling wave magnetic field to realize the soft control of liquid flow rate in drip irrigation pipelines. First of all, the structure of the combined traveling wave magnetic field generator was designed. COMSOL physical field simulation software was used to build the traveling wave magnetic field simulation model, and the magnetic field distribution diagram and the variation curve of the magnetic field intensity were generated in the time domain. Then, through the analysis of the simulation model, the harmonic interference of a single row and combined traveling-wave magnetic field generator is compared, and the optimal spacing between the traveling-wave magnetic field generator units is determined. Finally, the water-fertilizer fusion liquid used in the process of agricultural irrigation was selected and the liquid speed regulation experiment was carried out. The experimental results show that the combined liquid speed regulating device can effectively reduce the number of traveling wave field harmonics, compared with the single wave field generator at the same power, the magnetic field intensity is increased by 33.9 %. When the excitation current is 2 A and the initial flow rate is 0.5 m/s, the device can increase the flow rate of water-fertilizer fusion liquid for agricultural drip irrigation by 2.27 % and decrease by 2.13 %, which can meet the real-time and effective speed regulation requirements of water-fertilizer fusion liquid in the process of agricultural drip irrigation.

Elsaady W., Moughton C., Nasser A., lacovides H.

Continuous demands on resources of energy heighten the need for better and smarter use of available resources. Induction heating (IH) is a technology that is proved to be more efficient in many industrial applications compared to direct resistive heating. Also, IH can be used in domestic devices, as it provides clean and contactless regime of heating. In this paper, a fully coupled numerical approach of a domestic IH system for water boiling is presented. The approach couples the modelling of magnetic field generated in the system with both heat transfer and fluid flow phenomena. The nonlinear and temperature-dependent characteristics of materials are accounted for in the coupled numerical approach. The numerical approach is validated by experimental measurements that are implemented for four case studies. In addition, a detailed parametric study is presented to investigate the effects of different design parameters. The results provide a picture of the nonlinear, complex, transient buoyancy-driven fluid motion. It is found that the heating efficiency is highly affected by different design parameters such as susceptor material, thickness, and offset distance from the bowl base. These effects are highly nonlinear due to the inclusion of nonlinear magnetic and thermal characteristics. The results also highlight the importance of the investigation of IH systems as integrated systems, in contrast to most of existing similar studies. By this holistic approach, different thermal processes and effects of different design parameters are involved, and consequently the heating efficiency can be clearly assessed.

Berga K.K., Berenis D., Kalvāns M., Krastiņš I., Beinerts T., Grants I., Bojarevičs A.

In order to obtain a uniform thermal distribution of a liquid metal melt in e.g. aluminum furnaces, mixing can be provided by rotating permanent magnets. A rotating permanent magnet generates a rotating magnetic field which induces a volume force in the nearby liquid metal. This paper presents a quick-and-dirty experimental and numerical study of temperature equalization with a permanent magnet for a liquid metal volume with a vertical temperature gradient. Thermocouples and a thermal camera have been used to capture the temperature dynamics. The setup consists of a thin walled stainless steel container filled with GaInSn eutectic alloy and a cylindrical NdFeB permanent magnet placed near the side wall. A parametric sweep has been performed by changing the inclination angle of the magnet in order to find the most efficient position for which the thermal balance can be achieved the fastest.

Skrigan I.N., Lopukh D.B., Vavilov A.V., Martynov A.P.

A mathematical model is presented for the motion of solid particles in a borosilicate glass melt using cold hearth melting. The spatial distribution and deposition of noble-metal particles in industrial induction conical and flat-bottom furnaces is studied. The advantage of a conical-bottom furnace for retention of dispersed particles in the melt in suspension and their removal with discharged glass is shown. The obtained results are confirmed experimentally.

Tarasov F.E., Shmakov E.I.

The paper is concerned with numerical study of parameters of the magnetic system for induction heating of the large-size installations. The paper is included in a papers series concerning development of the installation for maintaining the specified pressing tool temperature for a long time period, more than 24 hours. Induction heating is the basic heating mechanism. Studies of the energy parameters depending on the power frequency are presented in this section of the paper. Determination of the basic frequency dependencies of efficiency and heat release is the objective of the paper. The studies were performed using numerical modeling in a three-dimensional formulation by the finite element method. A parametric study was carried out in which the frequency of the supply current was changed from 50 Hz to 60 kHz. During the study, the dependences of total electromagnetic power, volumetric loss density and efficiency on frequency were obtained. It was found that the optimal frequency for the most efficient induction heating process is 10 kHz.

Tarasov F.E., Shmakov E.I.

The paper is concerned with numerical study of parameters of the magnetic system for induction heating of the large-size installations. The paper is included in a papers series concerning development of the installation for maintaining the specified pressing tool temperature for a long time period, more than 24 hours. Induction heating is the basic heating mechanism. Studies of the inductor parameters depending on the power frequency are presented in this section of the paper. Study of the power supply parameters is the objective of the paper. The studies were performed using numerical modeling in a three-dimensional formulation by the finite element method. The study of the frequency influence of the inductor supply on the coils resistance and the power factor in the range of 0 - 60 kHz has been carried out. Numerical results have shown that increasing the frequency leads to a linear increase in the resistance of the coils and a decrease in the power factor.

Bicakci S., Coramik M., Gunes H., Citak H., Ege Y.

In this study, a new field-programmable gate array (FPGA)-based electromagnetic stirrer system was developed allowing mixing on a single axis, and the energy efficiency of the system was increased with fuzzy logic control. The electromagnetic stirrer system was designed with three phases and each phase is fed with pulsewidth modulation (PWM) voltage with 120° phase difference. Ranked control of phases in the system used the FPGA structure in the myRIO® embedded system to determine the PWM signal production, increase intervals for phase frequencies, and rotation rate of the magnetic stir bar. In the system, to increase the energy efficiency with fuzzy logic control, the ARM® microcontroller structure in the myRIO® embedded system was used. Programming of the myRIO® embedded system was provided through the graphic-based LabVIEW ® software. In situations where the system is operated with 100% duty cycle, the force affecting the magnetic stir bar should be continuous and have fixed value until the next phase change. As a result, the magnetic stir bar performs more than 120° rotation and a braking effect of the force is observed. To resolve this situation, fuzzy logic control ensured operation of a different duty cycle without loss of speed of the stir bar. Thus, the energy efficiency of the system was increased with lower current and lower stimulation duration. Within the scope of this article, the experimental results obtained about the structure, control, and energy efficiency of the electromagnetic stirrer system are discussed in detail.

Liu Z., Zhu X., Shao S., Liu Z., Wei X.

In order to improve the flow state of the liquid in the electromagnetic stirrer for aluminum alloy liquid and reduce the volume of the device, the structural parameters of the electromagnetic stirrer for aluminum alloy liquid were optimized by using the finite element model combined with the optimization method of NSGA-II multi-objective genetic algorithm. The relationship between the flow rate of aluminum alloy liquid after optimization and the magnitude and frequency of loading current was simulated and analyzed. The results show that: compared with the original structure, the optimized structure has smaller yoke volume, and can produce more suitable electromagnetic field and flow field distribution. Further studies show that the flow rate of molten aluminum alloy increases linearly with the increase of loading current when the current frequency is constant, and decreases with the increase of current frequency when the current is constant. The research results provide a theoretical basis for determining the optimal operating parameters of the electromagnetic stirrer, and a new method for the optimization design of the electromagnetic stirrer based on the finite element model.

Yerasimou Y., Pickert V., Dai S., Wang Z.

The press-pack packaging technology has been adopted in recent years for insulated-gate bipolar transistors (IGBTs) to be utilized in high voltage-high current applications, such as high-voltage direct current (HVdc) electric power transmission. Traditionally, the heat management of such systems is based on water coolant; however, there are numerous challenges associated with that method, such as the requirement to deionize the water to prevent electrical potentials and inherent problems of corrosion and leakage in the cooling piping structure. This article presents the design and development of a liquid metal heat sink for press-pack IGBTs. The use of a thermal management system based on liquid metal increases the heat dissipation capability without corroding the cooling structure. Analytical work is performed on the design of the heat sink. Moreover, the thermal performance of the heat sink is experimentally validated against a commercial water-based cooling system. The presented results show that the cooling performance of the liquid metal system is increased, whereas the shortcomings of the water-based system are eliminated.

Telicko J., Jakovics A.

Hussain M.

Since its inception in 2015, the YOLO (You Only Look Once) variant of object detectors has rapidly grown, with the latest release of YOLO-v8 in January 2023. YOLO variants are underpinned by the principle of real-time and high-classification performance, based on limited but efficient computational parameters. This principle has been found within the DNA of all YOLO variants with increasing intensity, as the variants evolve addressing the requirements of automated quality inspection within the industrial surface defect detection domain, such as the need for fast detection, high accuracy, and deployment onto constrained edge devices. This paper is the first to provide an in-depth review of the YOLO evolution from the original YOLO to the recent release (YOLO-v8) from the perspective of industrial manufacturing. The review explores the key architectural advancements proposed at each iteration, followed by examples of industrial deployment for surface defect detection endorsing its compatibility with industrial requirements.

Yang B., Liu Y., Liu P., Wang F., Cheng X., Lv Z.

Traditional ventilation and air conditioning systems typically operate on a predetermined schedule with fixed operating parameters. Occupant-centric control (OCC) strategies have been proposed to reduce system operation energy consumption without sacrificing thermal comfort. Indoor occupancy detection in real time is a critical step in successfully implementing the OCC strategy. Thus, the deep learning-based computer vision method was adopted in the first step of the study, and the detection performance and camera position were analyzed in an office scenario. Next, the proposed OCC strategy was used to regulate the supply air parameters and outdoor air volume in stratum ventilation based on the monitored occupant number. The traditional static control strategy was then compared to two control strategies: constant air volume and variable air volume. Occupant detection performance results showed the mean NRMSD for the five most common relative positions of the occupants and camera was 0.1109, with sitting back to camera having the lowest accuracy. Subjective response results demonstrated that, when compared to the traditional control strategy, thermal comfort was improved by 43%–73%, perceived air quality was maintained at an acceptable level, CO2 concentration was less than 700 ppm, and energy could be saved by 2.3%–8.1%. Furthermore, the lower the occupancy, the greater the improvement in comfort and the greater the energy savings. This research focused on how the stratum ventilation system responds to dynamic changes in occupancy and provided insights into reducing unnecessary energy waste while maintaining comfort.

Wang Y., Wu X., Gao J., Feng A., Wang J., Liu D., Zhou X.

• Simplified models and numerical models were established for calculating the heat transfer and surface temperature of prefabricated floor or ceiling RHC system. • The calculated heat transfer and surface temperature using the simplified models and numerical models agreed well with the experimental test results. • Both the heat transfer and surface temperature linearly changed with the mean water temperature under heating and cooling conditions. • The pipe space clearly affected the heat transfer and surface temperature of prefabricated floor or ceiling RHC system. • The heat transfer and surface temperature varied greatly as the transition changed from laminar flow to transitional flow with the increasing of water flow velocity. Prefabricated radiant heating and cooling (RHC) system is a typical form of high efficiency and lightweight radiant terminal, which has been extensively used in the residential and non-residential buildings. Heat transfer and surface temperature are the key parameters for rational design of a prefabricated RHC system. Therefore, in this paper, based on the analysis of the heat transfer mechanism, simplified models and numerical models were established for calculating the heat transfer and surface temperature of the prefabricated floor or ceiling RHC system. Compared with experimental test results, when the supply water temperature increased from 35℃ to 50℃ under heating condition or from 13℃ to 19℃ under cooling condition, the relative errors calculated by the simplified models were between -10.8% and 3.7% and between -3.8% and 5.0% for the heat transfer and surface temperature of the prefabricated floor RHC system, and ranged from 0.8% to 6.9% and from -0.7% to 0.3% for the prefabricated ceiling RHC system. Moreover, the calculated heat transfer and surface temperature of the prefabricated ceiling or floor RHC system using the simplified models were highly consistent with the numerical simulation results. Hence, the calculation accuracy of the proposed simplified models for the heat transfer and surface temperature can meet the requirements of engineering application, which will provide the support for the rational design of a prefabricated floor or ceiling RHC system.

Wei S., Tien P.W., Chow T.W., Wu Y., Calautit J.K.

The present study investigated the potential of the application of a live occupancy detection approach to assist the operations of demand-controlled ventilation (DCV) systems to ensure that sufficient interior thermal conditions and air quality were attained while reducing unnecessary building energy loads to improve building energy performance. Faster region-based convolutional neural network (RCNN) models were trained to detect the number of people and occupancy activities respectively, and deployed to an artificial intelligence (AI)-powered camera. Experimental tests were carried out within a case study room to assess the performance of this approach. Due to the less complexity of people counting model, it achieved an average intersection over union (IoU) detection accuracy of about 98.9%, which was higher than activity detection model of about 88.5%. During the detection, the count-based occupancy profiles were produced according to the real-time information about the number of people and their activities. To estimate the effect of this approach on indoor air quality and energy demand, scenario-based modelling of the case study building under four ventilation scenarios was carried out via building energy simulation (BES). Results showed that the proposed approach could provide demand-driven ventilation controls data on the dynamic changes of occupancy to improve the indoor air quality (IAQ) and address the problem of under- or over-estimation of the ventilation demand when using the static or fixed profiles. • A CNN-based model was developed to perform occupancy counting and activity detection. • The occupancy information was detected for indoor air quality and building ventilation energy demand estimation. • Building energy modelling was carried out under different ventilation scenarios. • Live occupancy detection can assist HVAC operations to provide demand-driven ventilation controls.

Dzelme V., Telicko J., Jakovics A.

Abstract Capillary heat exchangers are a great alternative to conventional radiators or electric heaters when used with heat pumps due to larger area and therefore a lower working temperature. In this work, we study thermal conditions in a model room using either capillary or conventional heaters. Experimental measurements in a special test building are used to validate and adjust numerical models. The results show that the vertical temperature distribution is similar with both heating systems, but air flow velocities are considerably higher and floor temperature is less uniform in case of radiator heating. Overall, the capillary system provides more uniform thermal conditions.

Telicko J., Vidulejs D.D., Jakovics A.

Abstract Monitoring systems allow operators to accomplish the greatest comfort indoors, but, as a rule, the available parameters are not enough to analyse the epidemiological threat in buildings. Due to the pandemic and increasing incidence of the disease, there is a need for monitoring systems that can provide the necessary information to analyse the risk of infection. With timely notification of people about the risks, such a system could not only increase safety in buildings, but also save crucial resources such as the work of medical personnel. This paper presents an example of real-world implementation of a cheap and scalable system to indicate risks and inform people inside. To achieve this, an appropriate set of sensors and communication protocols was selected, and processing of indirect measurements with artificial intelligence (AI) algorithms was carried out on an embedded Jetson Nano computer. Based on the experiments and a review of the literature, the necessary parameters for measurements were selected. Detailed analysis of measured data for risk evaluation is provided in [1].

Telicko J., Jakovics A., Drirkis I.

This manuscript describes the development of a wireless sensor system for long term monitoring of temperature, humidity and heat flux reading within building structural elements, including places that are hard to reach using wired sensors. The system was tested in cold Latvian climate in 3 different buildings. The main objectives during the development phase were the maximization of network operational lifetime, ensurance of work stability and maintenance cost reduction to make the system feasible for wide use in practical applications. An optimal radio module and microcontroller combination yielded sufficient signal range and data transfer stability, as well as efficient control of energy consumption.

Shvydkii E.L., Bychkov S.A., Zakharov V.V., Sokolov I.V., Tarasov F.E.

A model is developed for an electromagnetic stirrer using a traveling magnetic field. Electromagnetic and hydrodynamic problems are simultaneously solved for a two-dimensional case by a finite element method. The behavior of impurities in a turbulent flow is calculated using the Stokes law. A nonstationary magnetic field is shown to be applied. The calculated spatial distribution of impurities has a homogeneous character in the liquid metal volume. The model is verified by measuring the magnetic induction in an experimental setup.

K. Bolotin, E. Shvydkiy, I. Sokolov

E. Shvydkiy, K. Bolotin, I. Sokolov

Nemethova E., Krajcik M., Petras D.

This study evaluates the potential of thermal comfort enhancement in a modern office building with high ratio of glazed façade and a heating / cooling system with high thermal inertia. Application of proper control strategies for HVAC systems is important to prevent overheating, overcooling and excessive energy consumption. In this paper, the effect of various control settings and strategies on the thermal comfort is studied. The study is performed on a validated simulation model for a representative thermal zone located in a real administrative building, called the Energetikum.

Bolotin K.E., Sokolov I.V., Bychkov S.A.

Shape optimization occupies an important place in the development of MHD-stirrer for liquid metal, allowing to reduce economic and time costs. For all importance and relevance, there is still no unequivocal opinion as to which optimality criterion should be chosen: integral electromechanical force, integral melt velocity or time of technological process, for example, equalizing temperature in the melt volume. Present paper is devoted to comparing results of magnetic core optimization for MHD-stirrer with a traveling EM field for listed optimality criteria. As a parameter, by which efficiency of obtained result was evaluated, the time taken to equalize temperature in the melt volume was chosen.

Ivanov A.N., Bukanin V.A., Zenkov A.E.

A description of ICF ELTA (Induction Crucible Furnace Electro-Thermal Analysis) program and several results of simulation using this program are described. Main attention is paid to non-conductive and conductive types of crucible. Problems of metal melting both in first type and in graphite crucible are presented.

Slazhniev M.A., Kim K.H., Sim H.S., Kim S.W., Kim W.J.

In this study, there are presented design and conceptual approaches developments for 2 (two) kinds of the original complex technological foundry equipment for the melting, holding and managed electromagnetic magneto-hydrodynamic high-strength aluminum alloys pouring at continuous billet casting processes.