Temperature Distribution In Slab Research Articles

Analysis of dual-phase-lag heat conduction in a two-dimensional slab heated by a moving annular laser pulse

The controlled scan of a laser beam is at the core of the technology used for the micromachining of metals. To improve the laser micromachining of metal surfaces and reduce the thermal stress caused by the difference in temperature obtained in the process, a moving annular pulse laser heat source is introduced in present work. A mathematical model based on the dual-phase-lag (DPL) model is formulated to simulate the temperature response in a finite two-dimensional slab heated by the moving annular pulse laser heat source. Green's function approach and the superposition method are used to develop an analytical solution for the temperature field, and influences of the ratio of the thermalization time to the relaxation time of heat flux vector on the slab temperature distribution are investigated. The laser parameters that comprise the inner and outer radii are also examined to determine the induced temperature characteristics and advantages of the novel heat source.

The foam concrete temperature measuring during its microwave heat treatment

The actual problem of accelerating and reducing the energy costs of the foam concrete slabs heat treatment technological process is considered. It is shown that to solve this problem, it is advisable to use the microwave radiation energy as a heat source. The main advantages of the microwave method of foam concrete slabs heat treatment in comparison with traditional methods are considered. The design of a microwave installation for the foam concrete slabs heat treatment has been developed. The installed microwave radiation sources have energy outputs in the form of a rectangular waveguide openings, which are used as radiating antennas. Huygens-Kirchhoff method was used to calculate the temperature distribution on the foam concrete slab surface; the method of loaded long lines was used to calculate the temperature distribution over the foam concrete slab thickness. A method for measuring the foam concrete slab temperature distribution is proposed. The results of theoretical and experimental temperature distribution studies on the surface and the cross-section of foam concrete slab with a width of 1500 mm, a height of 1000 mm and a thickness of 200 mm, a density of 1000 kg/m3 on the electromagnetic fields oscillation frequency of 2450 MHz are shown. The obtained experimental results showed a high efficiency of using microwave radiation for the foam concrete slabs heat treatment technological processes. Microwave technologies can be used for heat treatment of products made of concrete, reinforced concrete and polymer composite materials.

Numerical analysis of the heat transfer of radiant tubes and the slab heating characteristics in an industrial heat treatment furnace with pulse combustion

For a heat treatment furnace, the precise study of the flow characteristics, combustion and heat transfer in the furnace is essential to know the temperature distribution in a slab during the heating process. In this context several different three-dimensional CFD (Computational Fluid Dynamics) models have been developed to simulate the combustion and heat transfer process in the furnace. These models were developed based on direct fired reheating furnaces with continuous fuel input. In this paper, a novel three-dimensional transient CFD model used to investigate the slab heating characteristics in the heat treatment furnace with pulse combustion was developed. The transient calculation in the furnace was performed based on the steady-state simulation of the furnace temperature, and the movement of slabs on the rollers in the furnace was simulated using dynamic mesh. By comparison, the results from the EDC with two different reaction mechanisms showed good consistency. However, the EDC with the two-step reaction mechanism required one fifth the calculation time of the EDC with the GRI-Mech3.0, and was thus the preferred model. In contrast to direct fired reheating furnaces, the outer radiant tube walls were treated as the coupled boundary conditions in the model to realize indirect heat transfer between the process gas in the furnace and the combustion gas in the radiant tubes. Furthermore, a pulse combustion method was proposed to control the working states of the burners based on UDF (User-Defined Function), in order to realize the pulse combustion process in the heat treatment furnace. By the validation of “Black Box”, the temperature variation of the slab and the gas temperature in the furnace predicted by the model agreed well with the experimental results. The simulation revealed that the temperature distribution of the radiant tubes and furnace gas was uniform and the maximum temperature difference on the outer radiant tube walls was less than 84 K. During the slab transient heating process, the slab temperature distribution became more uniform in the soaking zone and the maximum temperature difference along the thickness of the slab was below 13 K at discharge.

Ubiquitous Monitoring for Industrial Cyber-Physical Systems Over Relay- Assisted Wireless Sensor Networks

Ubiquitous monitoring over wireless sensor networks (WSNs) is of increasing interest in industrial cyber-physical systems (CPSs). Question of how to understand a situation of physical system by estimating process parameters is largely unexplored. This paper is concerned with the distributed estimation problem for industrial automation over relay-assisted WSNs. Different from most existing works on WSN with homogeneous sensor nodes, the network considered in this paper consists of two types of nodes, i.e., sensing nodes (SNs), which is capable of sensing and computing, and relay nodes (RNs), which is only capable of simple data aggregation. We first adopt a Kalman filtering (KF) approach to estimate the unknown physical parameters. In order to facilitate the decentralized implementation of the KF algorithm in relay-assisted WSNs, a tree-based broadcasting strategy is provided for distributed sensor fusion. With the fused information, the consensus-based estimation algorithms are proposed for SNs and RNs, respectively. The proposed method is applied to estimate the slab temperature distribution in a hot rolling process monitoring system, which is a typical industrial CPS. It is demonstrated that the introduction of RNs improves temperature estimation efficiency and accuracy compared with the homogeneous WSN with SNs only.

고온에 노출된 중공슬래브의 잔존성능 추정방법

Generally, the reinforced concrete slab has great fire resistance performance because concrete has excellent thermal material properties under fire. But, in the case of hollow slab, it will be expected that hollow slabs have different temperature distribution and fire endurance performance compare to reinforced concrete slab. Because hollow slab has internal void space that occurs decreasing regenerative effect of concrete and formation of internal air layer. Evaluation method for fire resistance performance of hollow slabs was proposed using wickstrom's method. For the casual use of evaluation, simplified method was proposed which was limited to solid slab and donut type hollow slab which was developed by authors of this research paper. Also, verification on proposed method was performed by comparing results of fire experiment for hollow slab and evaluation results. Proposed method of the results of this study was possible to predict the residual strength and temperature distribution of slabs under fire.

Effect of transverse distribution of secondary cooling water on corner cracks in wide thick slab continuous casting process

In the present work, a two-dimensional heat transfer model to describe the thermal behaviour of the wide thick slab during continuous casting process was developed, in which the boundary conditions for secondary cooling zone were calculated from the realistic water flux along the transverse surface of slab. The accuracy of the model calculation results were verified and calibrated by infrared thermography and nail shooting results. Furthermore, the slab temperature distribution under typical casting conditions were investigated numerically, and based on the hot ductility of microalloyed steel, the different arrangements of nozzles were optimized and designed to reduce the slab transverse corner cracks. The plant results showed that the defect rate of rolled plate corner and edge cracks were reduced from 12·6 to 3·5% with the optimised nozzles configurations.

Numerical Simulation of Induction Heating Process of Continuous Casting Slab

Compared with traditional blazing furnace, the Continuous Casting-Direct Rolling is an advanced manufacturing steel technology, which can reduce energy waste, decrease pollution and enhance efficiency. The characteristics of steels during induction heating are complex, the change of material properties with temperature makes exact analysis methods very difficult to implement. Therefore, a powerful computer aided numerical tool (i.e., finite difference analysis) is selected to numerically model the induction heating process in this paper. The mathematic model coupling with electromagnetic field and thermal field was established, and it was solved by finite difference method (FDM), thus the slab temperature distribution and its variation with time were obtained, and the characteristics in whole induction heating process were studied. To validate the program feasible, the results were evaluated and compared with experiment results, which showed that the simulation results are reliable and effective. The skin effect in heating process from the two results was studied and demonstrated, the temperature change caused by different parameters such as the induced power intensity and the corner radian were also presented, which indicate that the slab temperature can be heated uniformly through adjusting these parameters, thus the continuous casting slab can meet the rolling requirement.

Transient Temperature Analysis of Slab in Erdemir

Abstract A transient thermal model was developed for slab furnaces in Eregli Iron and Steel Works (Erdemir) in Turkey and the model was solved using the FlexPDE computer program. This program uses the finite element method. Program codes were written to solve the temperature distribution of slabs that are put into furnace at 25 °C and removed at about 1 250 °C. To obtain the optimum slab exit temperature variation, the necessary air temperature inside the furnace was calculated to be 1 390 °C. The slab temperature versus time and the temperature variation inside the slab were depicted.

Thermal and structural behaviour of a full-scale composite building subject to a severe compartment fire

This paper presents a numerical investigation of the thermal and structural results from a compartment fire test, conducted in January 2003 on the full-scale multi-storey composite building constructed at Cardington, United Kingdom, in 1994 for an original series of six tests during 1995–1996. The fire compartment's overall dimensions were 11 m×7 m with one edge at the building's perimeter, using largely unprotected steel downstand beams, and including within the compartment four steel columns protected with cementitious spray. The compartment was subjected to a natural fire of fire load 40 kg/m 2 of timber, in common with the original test series, but the composite slab forming its ceiling was subjected to a uniform applied load of 3.19 kN/m 2, which is higher than the original. Numerical modelling studies have been performed using the numerical software FPRCBC to analyse temperature distributions in slabs, manual Eurocode 3 Part 1.2 calculations for beam temperatures, and Vulcan to model the structural response to thermal and mechanical loading. These are compared with the quite comprehensive test data, and a series of cases has been analysed in order to develop a comprehensive picture of the sensitivity of the behaviour to different assumed conditions. The comparison between the modelling of basic cases and the test results shows very good correlation, indicating that such modelling is capable of being used to give a realistic picture of the structural behaviour of composite flooring systems in scenario-related performance-based design for the fire limit state. The extended sensitivity studies show the influence of extra protection to the connection zones of primary beams, and the effects of different vertical support conditions at the perimeter of the fire compartment. The effect of incomplete overlapping of the reinforcing mesh in the slab, which is believed to have occurred in one region, is also considered.

Mathematical Heat Transfer Model Research for the Improvement of Continuous Casting Slab Temperature

To improve the temperature of continuous casting slab, a mathematical heat transfer model simulating the solidification process of continuous casting slab was developed based on the technical conditions of the slab caster of Steelmaking plant of Wu-Han Iron and Steel Group Corp., by which the slab temperature distribution and shell thickness were computed. The adequacy of the model was compared with the measured slab surface temperature at the caster exit. The effects of the main operation parameters including casting speed, secondary cooling conditions, slab size and steel melt superheat on the solidification process were discussed and the means of enhancing the slab temperature was brought forward. Raising the casting speed from 1.0 or 1.1 to 1.3 m/min, controlling the flow rate of secondary cooling water and optimizing the spray pattern at the lower segments of secondary cooling zone could effectively improve the slab temperature. Whereas increasing the superheat is adverse to the production of slab with high temperature. The results of model research have been applied to plant operation at Steelmaking plant of Wu-Han Iron and Steel Group Corp. The slab surface temperature has risen from 900 to 1 250°C, and the slab are directly fed to the rolling mill after exiting caster.

Simulation of slab movement and transient heating in a continuous steel reheat furnace

This paper describes the simulation of transient heating of steel slabs in an industrial-scale continuous reheat furnace. To obtain a reliable slab temperature distribution, the gas flow and heat transfer were simulated with low-Reynolds-number turbulence models in combination with higher-order convection schemes and a radiation model. The transient heating of slabs was simulated with a moving slab technique, which allows the individual slabs to be heated up while moving along the furnace. Not only the individual slab movement and its temperature evolution can be tracked (Langrangian frame of reference), but the temperature distribution for all the slabs passing through the furnace can be monitored as well (Eulerian frame of reference). The developed model could simulate both the furnace start-up and steady-state operation. The simulation confirmed that both temperature profiles (Langrangian and Eulerian frames of reference) coincide in the pseudo-steady state operation. With the developed model, various issues from operation can be investigated in the future, such as skid mark effect and feeding capacity variations.

Effect of Roll Gap on Temperature Distribution in Slab during Steel Hot Rolling : A Bond Graph Approach

The aim of the present work is to show the influence of roll gap on the temperature distribution in slabs during the hot steel rolling deformation process. A Bond Graph model has been created to study the temperature distribution inside the material. Simulation studies for a typical low-carbon steel are presented in this work.

Prediction of Transient Slab Temperature Distribution in the Re-heating Furnace of a Walking-beam Type for Rolling of Steel Slabs.

This article is on heat transfer analysis by the commercial code, FLUENT, for slabs heated in a walking-beam type of a re-heating furnace in POSCO (Pohang Iron & Steel Co., Ltd.). Steady state, three-dimensional analysis is performed for turbulent reactive flow and radiative heat transfer in the furnace. Computation is based on the Favre-averaged conservation equations of mass, momentum, energy and species with the k-e turbulence model. The predicted global energy flow is in good agreement with the measurement. Two-dimensional transient calculation is performed for conduction in a slab with the boundary condition given in terms of the calculated local heat flux in the furnace. Results show substantial variation of the temperature across the furnace as well as between skid and non-skid regions in the slab. Parametric study is performed to examine skid mark severity and energy loss to the skid system with respect to the height and shape of the skid button and the convective heat transfer coefficient to cooling water. It is shown that the radiative exposure, which depends on the height and shape of the skid button, reduces skid mark severity by decreasing heat loss from the slab. The convective heat transfer coefficient to the cooling water turns out not to be of as much significance to skid mark severity as the exposure area of the skid button.

Numerical simulation of thermal process in steel industry

This note deals with a simulation algorithm for a reheating process of long steel products. In the steel industry, it is not always possible to measure the temperature of slabs during the reheating process. Therefore the well-known two-dimensional model of heat conduction with mixed convection-radiation boundary conditions is considered. This non-linear distributed system is discretized according to an implicit finite difference scheme and the temperature distribution of slabs is computed at each time instant by an efficient iterative algorithm.

Temperature Distribution in Materials with Positive Temperature Coefficients of Electrical Conductivity When Heated by Eddy Currents

Steady-state digital and analytical solutions are given for the temperature distribution in slabs and cylinders of materials heated by varying magnetic fields. The materials are assumed to have a positive temperature coefficient of electrical conductivity of the type associated with semiconductors. The stability of the temperature distribution is investigated. It is shown that the solutions can be either stable or unstable, depending upon the size of the sample. Some of the practical significance of such heating is discussEd in relation to the design of high-power wideband transformers.