OPTIMIZATION OF STATIONARY AND TRANSITIONAL OPERATING MODES OF THE ELECTRICAL COMPLEX IN METAL PROCESSING LINE

In the electrical complex “induction heater - deforming equipment”, the limiting performance of the complex is the induction heating unit. In this regard, an important task of increasing the effi ciency of the processing complex is to optimize both the design and operating parameters of the induction heating unit. It is shown that the main design parameter infl uencing the energy characteristics of the complex is the length of the heating system. When optimizing the total length of the heater, an iterative model of the process of induction heating of ferromagnetic billets is used. The power distribution algorithm along the length of a two-section heater is a piecewise continuous function. Optimization of the heater length according to the proposed method made it possible to reduce the heater length from 2.8 m to 2.1 m, i.e. by 25%. To search for eff ective control algorithms for non-stationary modes, a refi ned electrothermal model is proposed in the work. It takes into account the nonlinear dependence of the distribution of the power of the sources of internal heat release on the temperature distribution in the metal of the workpieces along the radial and axial coordinates. The problem of fi nding the optimal control of transient modes of a two-section induction heater of methodical action is formulated and solved. The results obtained provide a minimum of energy consumption for heating billets in transient modes under conditions of technological and energy constraints. Variants of starting the heater at various initial temperature states of the load are considered. The results of a comparative analysis of the eff ectiveness of the obtained control algorithms are presented. The structure of the power supply and control system of the induction heating complex is proposed.

Heat enhancement analysis of a differentially heated inclined square enclosure filled with Al2O3 nanofluids under three base fluids: Water, water-ethylene glycol mixture & ethylene glycol

This paper investigates the analysis of natural convection heat enhancement in an inclined square enclosure when filled with water-based nanofluids with left edge wall undergoing heating with consistent heat flux while the the right edge wall being cold and other remaining walls are kept adiabatic. The parameters used in this analysis include: solid fraction volume (range from 0% to 20%), length of the heaters (0.25cm, 0.50cm, and 1.0cm from the left edge), and Rayleigh number (range from 104 to 106). The nanolayer thickness ratio was kept at a constant value of 1.0 throughout the analysis. The heat source is found at the center of the left wall. Polynomial Differential Quadrature (PDQ) equations have been adopted for this analysis for various angles range from 0? to 90?. As the Rayleigh numbers and particle volume fraction got the much-needed raise, the average count of the heat transfer rate improved too. The length of the heat flux heater has become more prominent parameter that has been affecting the calculated temperature and the flow fields. When the heat flux heater length is pushed to an increasing limit, the heat enhancement rate essentially starts to decline. This happens at the smaller inclination angle, though.

Natural convection of $$\mathrm {Al}_{2}\mathrm {O}_{3}$$-water nanofluid in a non-Darcian wavy porous cavity under the local thermal non-equilibrium condition

This study investigates thermal natural convective heat transfer in a nanofluid filled-non-Darcian porous and wavy-walled domain under the local thermal non-equilibrium condition. The considered cavity has corrugated and cold vertical walls and insulated horizontal walls except the heated part positioned at the bottom wall. The transport equations in their non-dimensional model are numerically solved based on the Galerkin finite-element discretization technique. The dimensionless governing parameters of the present work are the nanoparticle in volume concentration, the Darcy number, number of undulations, modified heat conductivity ratio, dimensionless heated part length, and location. Comparisons with other published theoretical and experimental results show good agreement with the present outcomes. The findings indicate that the heater length, its position, and the waves number on the side vertical walls as well as the nanoparticles concentration can be the control parameters for free convective motion and heat transport within the wavy cavity.

Numerical study of magnetohydrodynamic mixed convective flow in a lid-driven enclosure filled with nanofluid saturated porous medium with center heater

This present numerical study explores the MHD mixed convective flow and heat transfer analysis in a square porous enclosure filled with nanofluid having center thin heater. The left and right walls of the enclosure are maintained at temperature T . The bottom wall is c considered with a constant heat source whereas the remaining part of bottom wall and top wall are kept adiabatic. The finite volume method based on SIMPLE algorithm is used to solve the governing equations in order to investigate the effect of heater length, Hartmann, Richardson, and Darcy numbers on the fluid-flow and heat transfer characteristics inside the enclosure. A set of graphical results are presented in terms of streamlines, isotherms, mid height velocity profiles and average Nusselt numbers. The results reveal that heat transfer rate increases as heater length increases for increasing Darcy and Richardson numbers. Among the two positions of heaters, larger enhancement of heat transfer is obtained for horizontal heater of maximum length. It is observed that, Hartmann number is a good control parameter for heat transfer in fluid-flow through porous medium in enclosure. Moreover, Ag-water nanofluid has greater merit to be used for heat transfer enhancement. This problem may be occurred in designing cooling system for electronic equipment to maximize the efficiency with active and secured operational conditions.

Buoyancy Induced Convection From Biheaters in a Cavity: A Numerical Study

A computational study of natural convection from biheaters of finite thickness and finite conductivity placed on a finite thickness and a finite conductive bottom plate of a cavity is performed under constant heat input condition. Cavity is cooled by the sidewalls, while the top and backside of the bottom plate are insulated. Streamline, isotherms, and local heat flux distribution of the sidewalls are discussed. Base Grashof number is chosen as 2.5 × 106. Biheater maintains a nondimensional distance of 0.4 between them. The left heater is placed at a nondimensional distance of 0.2 from the left wall. Heater length ratio is varied from 0.4 to 1.7, while heater strength ratio is varied from 0.25 to 7.0. Optimum operating temperature condition is found from the analysis.

Entropy Generation Analysis of Natural Convection in Square Enclosures with Two Isoflux Heat Sources

This study investigates entropy generation resulting from natural convective heat transfer in square enclosures with local heating of the bottom and symmetrical cooling of the sidewalls. This analysis tends to optimize heat transfer of two pieces of semiconductor in a square electronic package. In this simulation, heaters are modeled as isoflux heat sources and sidewalls of the enclosure are isothermal heat sinks. The top wall and the non-heated portions of the bottom wall are adiabatic. Flow and temperature fields are obtained by numerical simulation of conservation equations of mass, momentum and energy in laminar, steady and two dimensional flows. With constant heat energy into the cavity, effect of Rayleigh number, heater length, heater strength ratios and heater position is evaluated on flow and temperature fields and local entropy generation. The results show that a minimum entropy generation rate is obtained under the same condition in which a minimum peak heater temperature is obtained.

Magnetohydrodynamic mixed convection in a lid-driven rectangular enclosure partially heated at the bottom and cooled at the top

In the present study, numerical simulation of magnetohydrodynamic (MHD) mixed convection heat transfer and fluid flow has been analyzed in a lid-driven enclosure provided with a constant flux heater. Governing equations were solved via differential quadrature (DQ) method. Moving wall of the enclosure has constant temperature and speed. The calculations were performed for different Richardson number ranging from 0.1 to 10, constant heat flux heater length from 0.2 to 0.8, location of heater center from 0.1 to 0.9, Hartmann number from 0 to 100 and aspect ratio from 0.5 to 2. Two different magnetic field directions were tested as vertical and horizontal. It was found that results of DQ method show good agreement with the results of literature. The magnetic field was more effective when it applied horizontally than that of vertical way. In both direction of magnetic field, it reduced the flow strength and heat transfer. Thus, it can be used as an important control parameter for heat and fluid flow.

Finite Element Analysis of Heater Length in a Porous Annulus - Part B

The present study is undertaken to investigate the effect of geometrical and physical parameters on discrete heating of an annular vertical porous cylinder heated isothermally at center portion of inner radius. Finite element method is employed to convert the governing partial differential equations into matrix form of equations by employing 3 noded triangular elements. Darcy model is assumed to represent the flow behavior inside the porous medium. Two temperature model is used to describe energy flow in the medium. The study is conducted for different lengths of heater corresponding to 20%, 35% and 50% of the total height of the cylinder. It is found that the flow pattern for aspect ratio 1 is smoother than that of the 0.5.

Finite Element Analysis of Heater Length in a Porous Annulus - Part A

The focus of present study is to investigate the influence of discrete heating by an isothermal heater placed at the inner radius of a vertical annular cylinder containing porous medium between its inner and the outer radius. Finite element method is used to solve the governing partial differential equations by employing 3 noded triangular elements. Darcy model is used to represent the flow behavior inside the porous medium. It is assumed that the thermal non-equilibrium condition exists between the fluid and solid phases of the porous medium. The study is conducted for different lengths of heater corresponding to 20%, 35% and 50% of the total height of the cylinder. It is found that the Nusselt number for fluid, solid phases as well as total Nusselt number initially decreases and the increases along the length of heater.