scholarly journals Mathematical Model for Optimization of Heat Exchange Systems of a Refinery

2020 ◽  
Vol 161 ◽  
pp. 01001
Author(s):  
Vladimir Aleksandrovich Lebedev ◽  
Ekaterina Aleksandrovn Yushkova
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Exergy Analysis ◽  
Parametric Optimization ◽  
System Optimization ◽  
Automated System ◽  
Thermal Processes ◽  
Pinch Analysis ◽  
Relevant Today ◽  
Qualitative Characteristics

The article is devoted to the issue of thermodynamic optimization of heat transfer systems. Optimization is carried out by an exergy pinch method. This method includes the advantages of exergy analysis and pinch method. Exergy analysis takes into account the quantitative and qualitative characteristics of thermal processes, the pinch method allows structural and parametric optimization of heat transfer systems. The article presents a mathematical model for optimization by exergy pinch analysis. This model allows automated system optimization. Exergy pinch analysis allows more efficient use of energy and resources at the enterprise, which is relevant today.

scholarly journals Mathematical model for optimization of heat exchange systems

2020 ◽  
Vol 164 ◽  
pp. 02011
Author(s):  
Vladimir Lebedev ◽  
Ekaterina Yushkova
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Exergy Analysis ◽  
Parametric Optimization ◽  
System Optimization ◽  
Automated System ◽  
Thermal Processes ◽  
Pinch Analysis ◽  
Relevant Today ◽  
Qualitative Characteristics

The article is devoted to the issue of thermodynamic optimization of heat transfer systems. Optimization is carried out by an exergy pinch method. This method includes the advantages of exergy analysis and pinch method. Exergy analysis takes into account the quantitative and qualitative characteristics of thermal processes, the pinch method allows structural and parametric optimization of heat transfer systems. The article presents a mathematical model for optimization by exergy pinch analysis. This model allows automated system optimization. Exergy pinch analysis allows more efficient use of energy and resources at the enterprise, which is relevant today.

scholarly journals Exergy pinch analysis of a furnace in a primary oil refining unit

2019 ◽  
Vol 124 ◽  
pp. 05088
Author(s):  
Vladimir Lebedev ◽  
Ekaterina Yushkova ◽  
Ivan Churkin
Keyword(s):  
Energy Efficiency ◽  
Exergy Analysis ◽  
Energy Resources ◽  
Oil Refining ◽  
Thermal Processes ◽  
Pinch Analysis ◽  
Specific Design ◽  
Refining Unit ◽  
Qualitative Characteristics ◽  
Exergy Losses

The article considers the issue of thermodynamic optimization of heat power equipment. The solution to this problem allows one to increase the energy efficiency of heat systems by reducing the energy resources consumption. The article compares the traditional (enthalpy) pinch method and the exergy pinch method. The exergy method of thermodynamic analysis allows one to take into account both quantitative and qualitative characteristics of thermal processes. A furnace that heats oil in the ELOU AT-6 primary oil refining unit was selected as an object of the study. The results obtained using the traditional pinch method showed that the furnace does not require optimization. However, the exergy analysis showed that the furnace has exergy losses. The method of exergy pinch analysis allows us to formulate and justify specific design measures aimed at increasing the furnace energy efficiency. Using the exergy pinch analysis, one can identify the unused exergy and determine the part in which the loss occurs.

scholarly journals Selecting the rational electrodes location in a DC multi-electrode arc furnace

Vestnik IGEU ◽  
2020 ◽  
pp. 23-31
Author(s):  
A.L. Kukharev
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Design Parameter ◽  
Scientific Data ◽  
Design Parameters ◽  
Thermal Processes ◽  
Vortex Flows ◽  
Mixing Conditions ◽  
Transfer Parameters ◽  
Circle Diameter

One of the main design parameters of multi-electrode furnaces, which largely determines their heat and eco-nomic indicators, is the ratio of the pitch circle diameter of electrodes to the bath diameter Dp/Db. The existing methods for choosing rational design parameters are more relevant to arc furnaces operating on alternating current of industrial frequency. For multi-electrode direct current furnaces, which use magnetohydrodynamic effects to improve mixing conditions and temperature homogenization of the melt, there is no relationship between the heat transfer parameters and the pitch circle diameter of electrodes. This work is a continuation of a number of patents and articles. Elsewhere, the design was justified, a mathematical model of magnetohydrodynamic and thermal processes in the melt of the furnace containing three roof arc and three bottom electrodes was developed, the model was verified through the results of physical experiments, and the parameters of heat transfer in the furnace at Dp/Db ≈ 0,2 were studied. The proposed type of furnace requires the study of the Dp/Db effect on the heat transfer parameters in the melt, which will allow a rational choice of the design parameter. The results were obtained using a three-dimensional mathematical model of magnetohydrodynamic and thermal processes in the steel melt constructed with the non-induction approximation and taking into account the k- turbulence model. The results were processed using methods of analysis of vortex structures and estimation of the integral parameters of hydrodynamic and thermal processes in the molten bath. Numerical experiments have been carried out with the design parameter Dp/Db varying from 0,2 to 0,5. New scientific data on the patterns of changes in the structure of flows and heat transfer parameters in the molten pool of a six-electrode furnace have been obtained. Dp/Db increase within the indicated range causes the increase of intensity of vertical vortex flows circulating between the axis of the corresponding electric arc and the axis of the bath and of the azimuthal flows circulating in horizontal sections of the bath. Vortex flows formed due to natural convection near the side walls of the furnace are suppressed. The maximum value zones of the effective thermal conductivity that reaches 1,8·105 W/(m·K) are redistributed to the central part of the bath, which contributes to increasing temperature distribution efficiency in the bath. The obtained results allow recommending a rational range of values of Dp/Db within 0,4–0,5, which decreases the volume of stagnant zones in the proposed six-electrode furnace by more than 40 % and increases the integral values of the Nusselt number over the depth of the horizontal section of the bath on average by more than 10 %. The obtained data revealing the possibility of improving the mixing conditions and increasing the heat transfer efficiency in the melt of the six-electrode furnace can be recommended for choosing the Dp/Db ratio when designing high power furnace.

INFLUENCE OF HEAT TREATMENT OF MOUNTAIN MASSIVE ON TEMPERATURE MODE OF GEOTHERMAL CIRCULATION SYSTEM

2018 ◽  
pp. 44-50
Author(s):  
Yu. P. Morozov
Keyword(s):  
Heat Transfer ◽  
Operating Time ◽  
Fluid Motion ◽  
Coolant Temperature ◽  
Circulation System ◽  
Thermal Processes ◽  
Temperature Mode ◽  
Heat Influx ◽  
Stationary Heat Transfer

Based on the solution of the problem of non-stationary heat transfer during fluid motion in underground permeable layers, dependence was obtained to determine the operating time of the geothermal circulation system in the regime of constant and falling temperatures. It has been established that for a thickness of the layer H <4 m, the influence of heat influxes at = 0.99 and = 0.5 is practically the same, but for a thickness of the layer H> 5 m, the influence of heat inflows depends significantly on temperature. At a thickness of the permeable formation H> 20 m, the heat transfer at = 0.99 has virtually no effect on the thermal processes in the permeable formation, but at = 0.5 the heat influx, depending on the speed of movement, can be from 50 to 90%. Only at H> 50 m, the effect of heat influx significantly decreases and amounts, depending on the filtration rate, from 50 to 10%. The thermal effect of the rock mass with its thickness of more than 10 m, the distance between the discharge circuit and operation, as well as the speed of the coolant have almost no effect on the determination of the operating time of the GCS in constant temperature mode. During operation of the GCS at a dimensionless coolant temperature = 0.5, the velocity of the coolant is significant. With an increase in the speed of the coolant in two times, the error changes by 1.5 times.

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.

Second Law Analysis of Spray Evaporation

1990 ◽  
Vol 112 (2) ◽  
pp. 130-135 ◽  
Author(s):  
S. K. Som ◽  
A. K. Mitra ◽  
S. P. Sengupta
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Entropy Generation ◽  
Exergy Analysis ◽  
Droplet Evaporation ◽  
Second Law ◽  
Hot Gas ◽  
Second Law Analysis ◽  
Initial Drop ◽  
Parallel Stream

A second law analysis has been developed for an evaporative atomized spray in a uniform parallel stream of hot gas. Using a discrete droplet evaporation model, an equation for entropy balance of a drop has been formulated to determine numerically the entropy generation histories of the evaporative spray. For the exergy analysis of the process, the rate of heat transfer and that of associated irreversibilities for complete evaporation of the spray have been calculated. A second law efficiency (ηII), defined as the ratio of the total exergy transferred to the sum of the total exergy transferred and exergy destroyed, is finally evaluated for various values of pertinent input parameters, namely, the initial Reynolds number (Rei = 2ρgVixi/μg) and the ratio of ambient to initial drop temperature (Θ∞′/Θi′).

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