scholarly journals MATHEMATICAL SIMULATION OF THE HEATING SYSTEM RADIATOR OF AS A CONTROL OBJECT

2021 ◽  
Vol 11 (3) ◽  
pp. 38-43
Author(s):  
Alexander P. MASLYANITSYN ◽  
Elena V. MASLYANITSYNA ◽  
Marina S. KRASNOVA
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Transfer Function ◽  
Heat Carrier ◽  
Block Diagram ◽  
Thermal Power ◽  
Control Object ◽  
Heating System ◽  
Structural Diagram ◽  
Transfer Processes

The problem of mathematical modeling of a heating system radiator as a control object is considered. The purpose of its development is to create a generalized mathematical model of thermal processes in a room heated by means of water radiators. A calculation scheme of heat transfer processes between the heat carrier of the radiator and the air of the room has been developed, on the basis of which the heat balance equations are writt en. This takes into account both steady and unsteady heat transfer processes between the coolant, radiator and room air. A block diagram of the mathematical model of a heating radiator has been developed. After the introduction of assumptions and transformation of the structural diagram of the nonlinear model, the structural diagram of the linear mathematical model of the heating radiator was obtained. On its basis, the transfer function of the heating radiator is derived, the output coordinate of which is the thermal power. The resulting transfer function can be used in a generalized mathematical model of a heated room. The analysis of the transfer function of the heating radiator is carried out and it is shown that its dynamics is determined not only by geometric parameters, but also by the fl ow rate of the heat carrier.

THERMAL RESISTANCE OF POWER SEMICONDUCTOR MODULES OF SOLDERED CONSTRUCTION

2020 ◽  
Vol 5 ◽  
pp. 122-130
Author(s):  
S.I. MATYUKHIN ◽  
D.O. MALYI ◽  
A.S. VISHNYAKOV ◽  
E.Yu. ORLOV ◽  
V.I. KAZAKOV
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Computer Simulation ◽  
Thermal Resistance ◽  
Comsol Multiphysics ◽  
Power Semiconductor ◽  
Transfer Processes ◽  
Main Effect

The heat transfer processes in power semiconductor modules of soldered construction are studied using the methods of computer simulation in Comsol Multiphysics software. The problem of the thermal resistance of such modules is solved. The factors showing the main effect on the thermal resistance of the modules are studied. A mathematical model allowing engineering calculations of this resistance is developed.

Heat Transfer under a Flow of the Highly Viscous Crude Oil in a Buried Oil Pipeline

2021 ◽  
Vol 107 ◽  
pp. 122-128
Author(s):  
Aidar Kadyirov ◽  
Julia Karaeva ◽  
Ekaterina Vachagina
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Temperature Distribution ◽  
Crude Oil ◽  
Air Temperature ◽  
High Viscosity ◽  
Numerical Calculations ◽  
Oil Pipeline ◽  
Transfer Processes ◽  
The Republic

The paper presents a mathematical model and the results of numerical calculations of heat transfer processes during the flow of highly viscous crude oil in an oil pipeline. Comparison with literature data is performed. The samples of oil from the field of the Republic of Tatarstan (Russia) that are characterized by high viscosity were considered as crude oil. The influence of air temperature on the temperature distribution in the soil was investigated. The analysis of the distribution of crude oil temperature along the length of the pipeline was carried out.

scholarly journals ДВУХТЕМПЕРАТУРНАЯ МАТЕМАТИЧЕСКАЯ МОДЕЛЬ ГИДРОАККУМУЛЯТОРА С ТЕПЛОВЫМ РЕГУЛИРОВАНИЕМ ДЛЯ УСЛОВИЙ НЕВЕСОМОСТИ

2020 ◽  
pp. 12-21
Author(s):  
Полина Сергеевна Коваль ◽  
Константин Сергеевич Епифанов ◽  
Рустем Юсуфович Турна
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Single Phase ◽  
Saturation Temperature ◽  
Heat Fluxes ◽  
Zero Gravity ◽  
Detailed Model ◽  
Conservation Equations ◽  
Transfer Processes ◽  
Two Temperature

It is advisable to use two-phase heat transfer circuits (TPC) on spacecraft with high heat release in thermal control systems (TCS). TPC has many advantages over single-phase heat transfer loops. In such circuits, heat is accumulated and transferred in the form of latent heat of vaporization. TPC can transfer a much larger amount of heat per unit mass flow rate, the temperature of objects can be maintained almost constant throughout the heat supply area and close to the saturation temperature. Besides, all heat transfer processes occurring during boiling are more intense than with conventional convective heat transfer. Therefore, the mass and dimensions of the TCS based on the TPC will be less than based on single-phase circuits. The thermally regulated pressure accumulator (HCA) is the most important element of the TPC. The article proposes a simplified two-temperature mathematical model for describing nonequilibrium heat-mass transfer processes in HCA under zero gravity. The mathematical model of the HCA is formed using the method of idealized elements. The authors detail the energy conservation equations for control volumes and thermal units, mass conservation equations, equations for heat fluxes and mass sweats. It allows you to quickly carry out the calculation and analyze an acceptable result for preliminary estimates. Previously, the authors published the work, which describes a detailed multi-temperature model that allows us to estimate the nonequilibrium in the liquid phase. A detailed model allows you to calculate almost any process in the HCA with fairly high accuracy, but the program is quite voluminous and the calculation takes a lot of time. Therefore, on the recommendation of the developers of the AMESim software package, the authors formed a simplified two-temperature nonequilibrium HCA model. The model is implemented in Fortran software and tested to establish a quasistationary regime and tested for thermal balance. Based on the data of a space experiment on heating HCA with ammonia, the estimated value of the convective component of heat transfer under zero gravity is estimated. This concept and model can be refined based on the actual design of the accumulator. For example, equations can be written for a cylindrical HCA, placing the heater on the surface of the housing or in the center, etc.

scholarly journals STRUCTURAL DIAGRAM OF THE MODULE FOR DETERMINING THE LOCATION OF SMALL SPACE VEHICLES

T-Comm ◽  
2021 ◽  
Vol 15 (4) ◽  
pp. 28-34
Author(s):  
Evgeny A. Titenko ◽  
◽  
Alexander S. Sizov ◽  
Alexey N. Shevtsov ◽  
Ekaterina N. Schitova ◽  
...  
Keyword(s):  
Mathematical Model ◽  
High Performance ◽  
Moving Objects ◽  
Block Diagram ◽  
Space Vehicles ◽  
Continuous Control ◽  
Computational Domain ◽  
Structural Diagram ◽  
Small Spacecraft ◽  
Similar Solutions

Relevance. Known models, algorithms and technical solutions for determining the coordinates of aircraft are partially suitable for determining the location of small spacecraft, since the latter do not have their own means of determining and transmitting coordinates. This limitation does not allow continuous control of a small spacecraft and reduces its functionality. It is proposed to use the actively developing system of automatic dependent surveillance-broadcasting, installed on aircraft and allowing transmission of their coordinates, including to small spacecraft. Such aircraft are considered to be a kind of mobile reference objects in the airspace of the Earth. The study poses and solves a modified triangulation problem – determining the coordinates of a small spacecraft by the coordinates of reference moving objects (aircraft). Purpose. Development of a block diagram of a module that calculates the coordinates of a mobile spacecraft using a mathematical model for processing signals received from reference aircraft transmitting their own coordinates. Methods. Within the framework of the article, the main physical (Doppler effect) and geometric relationships of message transmission between receivers and transmitters and hardware and software solutions are considered, designed to obtain the processing of coordinates of message transmitters on board a small spacecraft. The results obtained make it possible to determine the location of the small spacecraft. The general block diagram of the coordinate determination module has a parallel organization and can be used in high-performance computing systems. On the basis of a mathematical model, an algorithm for determining the area of finding the apparatus and a block diagram of the coordinate processing module are obtained, characterized by the presence of a specialized parallel search unit. Modeling the algorithm on the reference data has shown the required accuracy in determining the area of the vehicle as a result of solving the modified problem. The obtained values of the variance of the computational domain indicate the efficiency of this approach and justify the hardware solution of the problem of determining the coordinates of a small spacecraft. Conclusion. The block diagram of the module for determining the position of the small spacecraft based on the ADS-B signals is the most compact and energetically less expensive solution than the GPS, which allows calculating the coordinates of the small spacecraft using a receiver, the consumption of the battery is only for receiving and processing data. In contrast to the presented scheme for receiving-processing and calculating the coordinates of the small spacecraft, existing similar solutions in a number of nanosatellites of the CubeSat standard are used, in addition to the processing algorithm and the receiving path, also transmitting equipment, which is many times more energy-intensive than the equipment presented in the form of a structural diagram of the position determination module ICA, in this article.

scholarly journals ОПРЕДЕЛЕНИЕ КОЭФФИЦИЕНТА КОНВЕКТИВНОГО ТЕПЛОПЕРЕНОСА В ГИДРОАККУМУЛЯТОРЕ С ТЕПЛОВЫМ РЕГУЛИРОВАНИЕМ ДЛЯ УСЛОВИЙ НЕВЕСОМОСТИ

2019 ◽  
pp. 10-15
Author(s):  
Полина Сергеевна Коваль ◽  
Эдем Русланович Решитов ◽  
Рустем Юсуфович Турна
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Convective Heat ◽  
Single Phase ◽  
Convective Heat Transfer Coefficient ◽  
Zero Gravity ◽  
Two Phase ◽  
Transfer Processes ◽  
Equilibrium Process ◽  
Two Phase Heat Transfer

In the modern world with the increasing power of spacecraft heat dissipation, the need has arisen to use efficient heat removal systems with two-phase heat transfer contours. Their advantages are determined by the fact that they can carry a much larger amount of heat per unit of consumption than when using a single-phase coolant. The energy consumption of the pump for pumping the coolant is insignificant, and the use of heat exchange during boiling allows you to maintain the temperature of objects almost the entire length of the circuit close to the saturation temperature. All heat transfer processes occurring with a change in the state of aggregation of a substance (boiling, condensation) occur much more intensively than during convective heat exchange in a single-phase liquid. A feature of this system is the change in mass of the coolant in the circuit when changing the operating modes of the two-phase heat transfer system. To regulate the amount of coolant in the circuit, as well as to maintain a predetermined pressure (boiling point), a hydraulic accumulator with thermal regulation (HCA) is used. The actual processes of heat and mass transfer in HCA are non-equilibrium, which complicates the calculation of the thermal control system. This paper describes the concept of a nonequilibrium mathematical model for calculating heat and mass transfer processes in HCA. It is shown that the nonequilibrium of processes can be taken into account by the convective heat transfer coefficient “k” in the mathematical model of HCA: k = 1 corresponds to the absence of convection; k > 100 corresponds to an equilibrium process. Based on the analysis of the flight space experiment for heating HCA, a prediction was made of the value of the convective heat transfer coefficient k under zero-gravity conditions. To assess the influence of the “k” value on the process of regulating the two-phase heat transfer contour under weightless conditions, it is recommended to use the values k = 30 ± 15. In ground-based experiments at high-intensity convection in HCA, processes are much more equilibrium than in zero gravity. It is concluded that the equilibrium process (high values of k) can be considered as more conservative concerning the regulatory process in weightlessness.

Automation of Concrete Heat Treatment in Thermoactive Formwork in Monolithic Housing Construction

2020 ◽  
Vol 897 ◽  
pp. 250-254
Author(s):  
Anatoly Fedorovich Tikhonov
Keyword(s):  
Heat Treatment ◽  
Mathematical Model ◽  
Control System ◽  
Transfer Functions ◽  
Block Diagram ◽  
Control Object ◽  
Housing Construction ◽  
Control Actions ◽  
Concrete Mix ◽  
Concrete Temperature

The block diagram and algorithm for concrete treating in thermoactive formwork is presented. Article presents parameters of the concrete mix, to enter in a command block before automated heating of the concrete mix in thermoactive formwork in accordance with the schedule of changes in concrete temperature in the process of obtaining desired strength. Article formulates mathematical model of the control object for thermal treatment of concrete with consideration of the specifics and general patterns, processes and technological requirements. Article determined control actions, transfer functions of the object and phase graph of the control system.

scholarly journals Synthesis of movement control mechanism for vertical guidance of supporting-rotary device measuring antenna complex of desired dynamics

2019 ◽  
pp. 6-10
Author(s):  
A. V. Aksenov
Keyword(s):  
Control System ◽  
Transfer Function ◽  
Supply Voltage ◽  
Block Diagram ◽  
Experimental Studies ◽  
Control Object ◽  
Parametric Identification ◽  
Antenna Complex ◽  
Measuring Antenna ◽  
Rotary Device

The parametric identification of the mechanism of vertical guidance of the support-rotary device of the measuring antenna complex is carried out. The transfer function is defined, which is presented as a model of the control object. The results of experimental studies allow to determine the average speed of movement of the pivoting device on the corner of the place with the required supply voltage. An integrator and a transfer function of the controller are introduced into the algorithm of the control scheme of the object position. The developed scheme of the control system allows to provide the dynamics corresponding to this speed. The block diagram of the control system implementing the necessary dynamics of the object is given. The control algorithm with the controller is studied using the Matlab 7.9.0 software package. The article presents the logarithmic frequency characteristics of open and closed systems. According to the results of the proposed method of synthesis of the controller for the device, the time of the transient process of the installation is determined; a smooth stop of the device is provided, oscillations are eliminated.

scholarly journals Entropy generation analysis and thermal characteristics of radiation heating system

2019 ◽  
pp. 327-327
Author(s):  
Andriy Redko ◽  
Igor Redko ◽  
Serhii Pavlovskiiy ◽  
Nataliia Kulikova ◽  
Artem Cherednik ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Water Temperature ◽  
Entropy Production ◽  
Flux Density ◽  
Radiation Flux ◽  
Cooling System ◽  
Thermal Power ◽  
Heating System ◽  
Thermodynamic Efficiency ◽  
Radiation Heat

This article presents the developed methodology for the numerical simulation of radiation heat transfer from water panel heaters and optimization results of water temperature in the supply pipeline from the mass flow rate of the heat-carrier and the surface area for a given thermal power of the panel system. A numerical mathematical model is developed in the assumption that heat transfer occurs by means of radiation heat exchange by longitudinal ribs and pipes, which are thermally insulated on top. It is assumed that the temperature of the rib base is equal to the temperature of the outer wall of the pipe. The irregularity of the radiation density in different directions depends on the angle and distance to the irradiated area. The aim of the work is to develop a methodology to simulate the heat transfer processes of a radiation panel water heating system and optimization of design and operating parameters. The radiation intensity is determined by a numerical method using the MATLsoftware package. Our results of experimental studies of the radiation flux density are presented and compared with the results of numerical ones. The thermodynamic efficiency of a panel heating system is analyzed using the entropy production method (exergy destruction). The multicriteria optimization of water temperature in the supply pipeline is performed by LP?-search. It is found that the unevenness of surface temperature of panels reaches 24.4% as well as for the panels of about 50m in length a decrease in water temperature to 20K is observed, which leads to the unevenness of radiation flux density over the heated area. The area of the cooling system as a function of water temperature and the conditions under which the entropy production in the system is minimal is determined.

A mathematical model of heat transfer processes in hardening high vacuum furnaces

Vacuum ◽  
1984 ◽  
Vol 34 (5) ◽  
pp. 533-539 ◽  
Author(s):  
A Del Puglia ◽  
B Tesi ◽  
T Bacci ◽  
M Revelli ◽  
G Tonini
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
High Vacuum ◽  
Transfer Processes ◽  
Vacuum Furnaces
Sign in / Sign up

Export Citation Format

Share Document