scholarly journals The Effects of Rotary Kiln Operating Conditions and Design on Burden Heating Rates as Determined by a Mathematical Model of Rotary Kiln Heat Transfer

1990 ◽  
Vol 40 (3) ◽  
pp. 337-344 ◽  
Author(s):  
Geoffrey D. Silcox ◽  
David W. Perching
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Rotary Kiln ◽  
Operating Conditions ◽  
Heating Rates

scholarly journals NUMERICAL RESEARCHING THE COMBUSTION AND HEAT TRANSFER WHILE HAYDITE BURNING IN A ROTARY KILN

2016 ◽  
Vol 2 (1) ◽  
pp. 170-174
Author(s):  
Кузнецов ◽  
Valeriy Kuznetsov
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Natural Gas ◽  
Rotary Kiln ◽  
Diffusion Flame ◽  
Gas Combustion ◽  
Thermal Operation ◽  
Natural Gas Combustion

A mathematical model has been elaborated and a computer simulating program has been made up with the help of which a numerical researches were fulfilled for natural-gas combustion and the heat transfer in a rotary kiln while haydite burning. Its thermal operation was considered to find the best conditions of heat transfer from the diffusion flame to expanding calcined granules.

scholarly journals Modeling for Pyrolysis of Solid Biomass

2019 ◽  
Vol 64 (2) ◽  
pp. 192-204
Author(s):  
Biljana Miljkovic ◽  
Branislava Nikolovski ◽  
Dejan Mitrović ◽  
Jelena Janevski
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Weight Loss ◽  
Degradation Mechanism ◽  
Volatile Matter ◽  
Point Of View ◽  
Experimental Results ◽  
Pyrolysis Kinetics ◽  
Heating Rates ◽  
Simulation Results

In comparison to coal, biomass is characterized by a higher content of volatile matter. It is a renewable source of energy which has many advantages from an ecological point of view. Understanding the physical phenomena of pyrolysis and representing them with a mathematical model is the primary step in the design of pyrolysis reactors. In the present study, an existing mathematical model is used to describe the pyrolysis of a single solid particle of biomass. It couples the heat transfer equations with the chemical kinetics equations. A finite difference method is used for solving the heat transfer equation and the two-step pyrolysis kinetics equations. The model equation is solved for a slab particle of equivalent dimension 0.001 m and temperature ranging from 300 to 923 K. An original numerical model for the pyrolysis of wood chips is proposed and relevant equations solved using original program realized in MATLAB.To check the validity of the numerical results, experimental results of pyrolysis of woody biomass in laboratory facility was used. The samples were heated over a range of temperature from 300 to 923 K with three different heating rates of 21, 32 and 55 K/min, and the weight loss was measured. The simulation results as well as the results obtained from thermal decomposition process indicate that the temperature peaks at maximum weight loss rate change with the increase in heating rate. The experimental results showed that the simulation results are in good agreement and can be successfully used to understand the degradation mechanism of solid reaction.

A Mathematical Model of Heat Transfer in a Rotary Kiln Thermo-Reactor

2005 ◽  
Vol 28 (12) ◽  
pp. 1480-1489 ◽  
Author(s):  
S.-Q. Li ◽  
L.-B. Ma ◽  
W. Wan ◽  
Q. Yao
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Rotary Kiln

INFLUENCE OF VAPOR AND CRYSTAL FORMATION PROCESSES ON HEAT EXCHANGE IN FILM VAPORATORS

2021 ◽  
pp. 32-40
Author(s):  
O. Koshelnik ◽  
V. Pavlova ◽  
T. Pugacheva ◽  
O. Kruglyakova ◽  
O. Dolobovska
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Energy Consumption ◽  
Heat Exchange ◽  
Solid Phase ◽  
Heat Transfer Process ◽  
Operating Conditions ◽  
Crystal Formation ◽  
Phase Content ◽  
Three Phase

Evaporators for changing the concentration of solutions have a different design, depending on the type of processed substance. Significant energy consumption in such equipment is associated with the need for removing large quantity of liquid phase. Multiple-effect evaporators are used to reduce the energy consumption of the evaporation process, but such equipment is quite expensive. Evaporators with secondary vapor heat reusing that operate in film mode can be an alternative to multi-effect evaporators. This equipment can operate efficiently across minimal temperature differences due to secondary vapor compressors. The disadvantage of this device is strict requirements for impurities in solutions. Impurities create deposits (incrustations) of various substances on the heat transfer surfaces, which worsens the operating conditions. If crystallizing solutions are used in evaporators with reusing of secondary vapor heat, then one of the ways to reduce the rate of heating surfaces incrustation is to add a solid phase to the initial solution. A mathematical model is proposed to describe the processes of heat and mass transfer during the film flow of crystallizing solutions, which are accompanied by a change in the physical characteristics of the solution and the formation of deposits. The model considers a three-phase liquid suspension with a varying phase content. Two stages of vaporization including vaporization on the surface of the liquid and on the surface of heat exchange are presented. The mathematical model involves the equations of continuity, energy and heat transfer, as well as the equations of motion of a three-phase flow with a changing phase content for both stages of vaporization, taking into account that solid phase turbulizes the flow and intensifies the heat transfer process. This mathematical model makes it possible to study the effect of the solid phase on heat transfer processes and the rate of incrustation in evaporators with reuse of secondary vapor heat.

scholarly journals STUDY OF A FLOWING-TYPE HEAT TRANSFER INTENSIFIER USED AS PART OF A THERMOELECTRIC SEA WATER DESALINATION SYSTEM

2019 ◽  
Vol 46 (3) ◽  
pp. 53-65
Author(s):  
Sh. A. Yusufov ◽  
A. R. Bazaev ◽  
B. A. Bilalov
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mathematical Model ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Operating Conditions ◽  
Thermal Battery ◽  
Additional Heat ◽  
System Solution ◽  
Thermoelectric Heat

Objectives To analyse the thermophysical processes in the thermoelectric heat transfer intensifier operating as part of a desalination system based on semiconductor thermoelectric converters.Method A mathematical model for the design of a desalter containing a thermoelectric heat exchanger, which provides for the use of heat flows by natural thermal conductivity due to so-called heat channels, is proposed. The proposed method of using additional heat sinks on the heat-absorbing side of the device and additional heat sources on the fuel side determines the need for a new mathematical model that differs from the known mathematical models describing heat transfer in the heat transfer flowing-type intensifier.Results The analysis of modelling results shows that a significant contribution to the temperature field of heat conductors is made when considering the heat transfer over the heat channels. The value of the contribution is the greater, the higher the thermal conductivity of the heat channels and the temperature difference between the heat conductors and the surface of the heat channels. In accordance with their purpose, flow-type thermoelectric heat transfer intensifiers (THTIs) for desalination applications must ensure efficient heat transfer from the cooled fluid flow to the heated fluid flow. The results show that, at a given limited length of the heat exchanger, the use of a thermoelectric battery together with heat channels allows equality of temperatures of heat conductors at the output to be achieved.Conclusion The modelling results show that, under the operating conditions of the thermal battery in intensifier mode, the length of the heat exchanger shall not exceed the value, at which the temperature of the heat conductor at the outlet becomes equal. The system solution provides the required length of the thermal battery, which allows equality of coolant temperatures to be achieved at the exit from the THTI operation mode. Following the logic of the desalter scheme under consideration, it is obvious that the reduction in the length of the heat exchanger, with all other things being equal, gives a reduction in the mass and size of the device as a whole.

Design of the Blast Furnace Wall Structure Made of Efficient Materials. Part 4. Calculation Examples

2020 ◽  
Vol 786 (11) ◽  
pp. 30-34
Author(s):  
A.M. IBRAGIMOV ◽  
◽  
L.Yu. GNEDINA ◽  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Blast Furnace ◽  
Boundary Value Problems ◽  
Transfer Process ◽  
Rational Design ◽  
Boundary Value ◽  
Heat Transfer Process ◽  
Furnace Wall ◽  
Time Interval

This work is part of a series of articles under the general title The structural design of the blast furnace wall from efficient materials [1–3]. In part 1, Problem statement and calculation prerequisites, typical multilayer enclosing structures of a blast furnace are considered. The layers that make up these structures are described. The main attention is paid to the lining layer. The process of iron smelting and temperature conditions in the characteristic layers of the internal environment of the furnace is briefly described. Based on the theory of A.V. Lykov, the initial equations describing the interrelated transfer of heat and mass in a solid are analyzed in relation to the task – an adequate description of the processes for the purpose of further rational design of the multilayer enclosing structure of the blast furnace. A priori the enclosing structure is considered from a mathematical point of view as the unlimited plate. In part 2, Solving boundary value problems of heat transfer, boundary value problems of heat transfer in individual layers of a structure with different boundary conditions are considered, their solutions, which are basic when developing a mathematical model of a non-stationary heat transfer process in a multi-layer enclosing structure, are given. Part 3 presents a mathematical model of the heat transfer process in the enclosing structure and an algorithm for its implementation. The proposed mathematical model makes it possible to solve a large number of problems. Part 4 presents a number of examples of calculating the heat transfer process in a multilayer blast furnace enclosing structure. The results obtained correlate with the results obtained by other authors, this makes it possible to conclude that the new mathematical model is suitable for solving the problem of rational design of the enclosing structure, as well as to simulate situations that occur at any time interval of operation of the blast furnace enclosure.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals Comprehensive Parameters Identification and Dynamic Model Validation of Interior-Mount Line-Start Permanent Magnet Synchronous Motors

Machines ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 4 ◽  
Author(s):  
Luqman S. Maraaba ◽  
Zakariya M. Al-Hamouz ◽  
Abdulaziz S. Milhem ◽  
Ssennoga Twaha
Keyword(s):  
Mathematical Model ◽  
Permanent Magnet ◽  
High Efficiency ◽  
Experimental Tests ◽  
Induction Machines ◽  
Test Methods ◽  
Operating Conditions ◽  
Test Method ◽  
Permanent Magnet Synchronous Motors ◽  
Synchronous Motors

The application of line-start permanent magnet synchronous motors (LSPMSMs) is rapidly spreading due to their advantages of high efficiency, high operational power factor, being self-starting, rendering them as highly needed in many applications in recent years. Although there have been standard methods for the identification of parameters of synchronous and induction machines, most of them do not apply to LSPMSMs. This paper presents a study and analysis of different parameter identification methods for interior mount LSPMSM. Experimental tests have been performed in the laboratory on a 1-hp interior mount LSPMSM. The measurements have been validated by investigating the performance of the machine under different operating conditions using a developed qd0 mathematical model and an experimental setup. The dynamic and steady-state performance analyses have been performed using the determined parameters. It is found that the experimental results are close to the mathematical model results, confirming the accuracy of the studied test methods. Therefore, the output of this study will help in selecting the proper test method for LSPMSM.

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