Furnace Transfer Research Articles

Oxygen and Nitrogen Transfer in Furnaces in Crystal Growth of Silicon by Czochralski and Directional Solidification Processes.

Impurity concentrations of oxygen, carbon, nitrogen, iron, and other heavy metals should be well controlled in silicon crystals to maintain the crystal quality for application in electronic and solar cell devices. Contamination by impurities occurs during the melting of raw materials and during the crystal growth process. Quantitative analysis of impurity transfer using numerical and experimental analysis is important to control impurity concentrations. This paper reviews the analysis of the impurity transport phenomena in crystal growth furnaces of Czochralski and directional solidification methods by a model of global analysis and an experiment during the crystal growth of silicon.

Calculations of Heat Transfer in Furnaces of Steam Boilers under Laws of Radiation of Gas Volumes and Development of Innovative Designs of Furnaces

The analysis of heat transfer in furnaces of steam boilers is carried out. Throughout the 20th century, due to the lack of precise methods of calculation in Russia and foreign countries, there was incomplete local information about the scope of heat fluxes in furnaces. After the discovery by the author of the laws of thermal radiation of gas volumes, it became possible to obtain accurate data on the distribution of heat flows along with the height and perimeter of the screen surfaces of fire chambers (furnaces). The executed calculations showed essential no uniformity of distribution of heat fluxes, vaporization, and in-pipe deposits on height and perimeter of screen surfaces of fire chambers. Proposed are innovative furnaces, in which the distribution of heat fluxes, vaporization, in-pipe deposits on the screen surfaces are leveled.

Impact Analysis of Intermediate Heat Carrier on Heat Transfer in Furnace

Intermediate heat carriers have been applied in engineering as enhanced heat transfer elements, but their theoretical analysis still needs to be improved. Therefore, an intermediate heat carrier is added to establish the quaternary model of the furnace gas under nongray radiation characteristics. Based on this model, an analytical expression of heat flux on the surface of the billet is derived. General rule of the impact of intermediate heat carrier on the thermal efficiency in the furnace can be properly derived by analytical calculation from a theoretical point of view. The results show that the longer the length of the intermediate heat carrier located at the top of the furnace, the greater the heat exchange capacity on the surface of the billet. Meanwhile, when the intermediate heat carrier is located in the center of the furnace top, the billet gets higher heat flux; the closer to both sides, the lower the heat flux. In addition, the influence that the surface emissivity of the intermediate heat carrier has on the heat transfer of the billet surface is related to the values of εg and αgw. Comparison with previous literature shows that adding intermediate heat carrier can improve the heat exchange capacity of billet.

Development of a New Burner Device Based on Injection-Radiation Method for Gas Fuel Combustion

This paper presents the results of designing a promising burner device that combines injection and radiation methods for gaseous fuel combustion. Infrared radiation from the heated surface of nozzle of radiation burner provides intensive heat transfer in furnaces and boilers, specifies their high efficiency at low flue gas temperatures, and very low NOx emissions. Effective gas combustion is facilitated by additional heating of the initial fuel mixture during filtration through the hot walls of porous nozzle. The new design of radiation burner has high performance characteristics, provides effective combustion of gaseous fuel up to 99% and meets high environmental standards and requirements.

A thermofluid network based methodology for integrated system simulation of heat transfer and combustion in a coal-fired furnace

Coal-fired power plant boilers are made up of several complex and interdependent subsystems that all need to work together properly to ensure plant availability, efficiency and safety, while limiting emissions to the environment. Having a process model where the relevant subsystems are coupled, and the interdependencies can be ascertained, is therefore invaluable. Such an integrated model may be based on a one-dimensional thermofluid network approach to model the water to steam cycle and the coal and air to flue gas cycle. If quick solution times are required, for instance in model based on-line process condition monitoring, such an integrated model cannot capture the same level of detail that would typically be available in a three-dimensional CFD model. However, even in a reduced model a three-dimensional approach may be required, for instance when modelling the thermal radiation heat transfer in the furnace. This paper proposes a network based methodology which combines the zonal method to model the radiation heat transfer in three dimensions with a one-dimensional burnout model for the heat generation, and characteristic flow maps for the mass transfer. The methodology was applied to the single burner furnace of the IFRF’s experimental facility at Ijmuiden in the Netherlands, for which extensive empirical data is available. The new model was used to predict the radial temperature profile near the furnace exit and the heat absorbed through the walls, as well as the temperature, carbon burnout, oxygen and carbon dioxide profile along the centerline of the furnace. To better understand the benefits and limitations associated with the specific combination of models implemented here, a CFD model was also developed and used for comparison. The results obtained with the new model compare well with the CFD benchmark, as well as the experimental results. This provides confidence that the combination of models applied here can be used to model the integrated behavior in the single burner furnace and forms the basis for expansion to utility scale boilers.

Method of calculating heat transfer in furnaces of small power

This publication presents the experiences and results of generalization criterion equation of importance in the analysis of the processes of heat transfer and thermal calculations of low-power heat generators cooled combustion chambers. With generalizing depending estimated contribution of radiation and convective heat transfer component in the complex for the combustion chambers of small capacity boilers. Determined qualitative and quantitative dependence of the integrated radiative-convective heat transfer from the main factors working combustion chambers of small volume.

HEAT AND MASS TRANSFER MODEL IN FURNACES IN THE SILICON CARBIDE PRODUCTION

The paper researches the process of heat and mass transfer in furnaces of the resistance in the silicon carbide production and considers a solid body with gas cavities and internal heat in general physical model of the process. Solid part is multicomponent and moist. The thermal conductivity with variable thermal parameters, variable porosity, the heat of chemical reactions, the process of drying the solid component, the generation of gas in chemical reactions and heat transfer seepage gas flow are taking into account. The mathematical description of the process is a system of two differential equations: the heat equation for a porous body with a chemically reactive components and heat transfer equation in the process of filtering the gas through the interconnected pores. Differential equations are supplemented by the necessary closing relations. Closing relations are the results of the considering of the processes model accompanying the silicon carbide production: the drying, calculating the pressure field in the system of interconnected pores, heat of chemical reactions and the effective thermal conductivity. The obtained mathematical model allows determining the temperature field, choosing variants of loading the furnace and regimes of melting in the silicon carbide production.

Regularities of heat transfer in the gas layers of a steam boiler furnace flame. Part II. Gas layer radiation laws and the procedure for calculating heat transfer in furnaces, fire boxes, and combustion chambers developed on the basis of these laws

The article presents the results stemming from the scientific discovery of laws relating to radiation from the gas layers generated during flame combustion of fuel and when electric arc burns in electric-arc steel-melting furnaces. The procedure for calculating heat transfer in electric-arc and torch furnaces, fire-boxes, and combustion chambers elaborated on the basis of this discovery is described.

Method for Handling Turbulent Fluctuation in Radiative Heat Transfer in Furnaces (Proposal of Efficient Method and Examination Based on Absorption Line Database)

An effective method is proposed for handling turbulent fluctuations of temperature and partial pressure of infrared-active gas in order to evaluate radiative heat transfer under the influence of turbulence-radiation interaction with fair accuracy and feasible calculation load, assuming large-scale industrial furnaces where the re-absorption of radiative energy by combustion gas on optical path toward objects to be heated cannot be neglected. The proposed method realizes feasible calculation load suitable to simulation tools based on two kinds of simplification. Firstly, assuming that temperature fluctuations of arbitrary two positions are independent from each other, local emission of radiative energy from turbulent combustion gas is treated as steady emission though its value is evaluated by averaging the fluctuating intensity corresponding to turbulence. Secondly, absorption of radiative energy by turbulent combustion gas on the optical path is evaluated based on the steady spatial distribution of absorption coefficient in correspondence to spatial distribution of time-averaged temperature. Validity of the proposed method is examined on a model optical path imaging the typical course of radiative energy in large-scale industrial furnaces. H2O is selected as fuel taking the reliability of absorption line database into consideration. Examination results indicate that the validity of proposed method is secured even if the cross-correlation of temperature fluctuation extends over realistic distance and even if the fluctuation intensity is fairly large. The error attendant to proposed method is sufficiently smaller than the error raised by entire neglect of turbulent fluctuation of temperature and gas composition.

An Efficient Method of Non-Gray Analysis for Studying Raditive Heat Transfer in Furnaces with Comparable Accuracy to Line-by-Line Analysis (Proposal of Method and Examination in Isothermal Field)

An Efficient Method of Non-Gray Analysis for Studying Raditive Heat Transfer in Furnaces with Comparable Accuracy to Line-by-Line Analysis (Proposal of Method and Examination in Isothermal Field)

An Efficient Method of Non-Gray Analysis for Studying Raditive Heat Transfer in Furnaces with Comparable Accuracy to Line-by-Line Analysis (Proposal of Method and Examination in Non-Isothermal Field)

An Efficient Method of Non-Gray Analysis for Studying Raditive Heat Transfer in Furnaces with Comparable Accuracy to Line-by-Line Analysis (Proposal of Method and Examination in Non-Isothermal Field)

New Weighted Sum of Gray Gases Model Applicable to Computational Fluid Dynamics (CFD) Modeling of Oxy−Fuel Combustion: Derivation, Validation, and Implementation

Radiation is the principal mode of heat transfer in furnaces. Models for gaseous radiative properties have been well-established for air combustion. However, there is uncertainty regarding their applicability to oxy−fuel conditions. In this paper, a new and complete set of weighted sum of gray gases model (WSGGM) is derived, which is applicable to computational fluid dynamics (CFD) modeling of both air−fuel and oxy−fuel combustion. First, a computer code is developed to evaluate the emissivity of any gas mixture at any condition using the exponential wide band model (EWBM), and the calculated results are validated in detail against data in the literature. Then, the validated code is used to generate emissivity databases for representative air- and oxy-firing conditions, for each of which a refined WSGGM with new parameters is derived. The practical way to implement the model to CFD simulations of combustion systems is given. Finally, as a demonstration, the new model is implemented to CFD modeling of two ...

Calculation of heat transfer in boiler furnaces during firing of fuel in a bed

A method for calculating complex heat transfer in furnaces is proposed, central to which is using the experimentally determined temperature of the bed of burning solid fuel.

Three-dimensional global modeling of a unidirectional solidification furnace with square crucibles

A new model for three-dimensional (3D) global simulation of heat transfer in a unidirectional solidification furnace with square crucibles was proposed. Convective, conductive and radiative heat transfers in the furnace are solved together in a coupled way by using a finite volume method. An efficient algorithm for view factor calculations in modeling radiative heat transfer and a mixed 2D/3D space discretization technique were developed. With coupling a 2D transient global simulation, the proposed 3D global model can be used to investigate 3D features of heat transfer in the entire furnace throughout a whole solidification process with moderate requirement of computation resources. Some typical results of 3D features of a unidirectional solidification furnace for producing multi-crystalline silicon used for solar cells were presented as a case study.

Applicability of the standard method for calculating heat transfer in furnaces with stokers

Features pertinent toheat transfer in furnaces during combustion of solid fuel in a bed are considered. The results from the tests are compared with the calculated characteristics of heat transfer. A conclusion is drawn regarding the need to revise the calculation method for furnaces with a bed of burning fuel.

Heat Transfer in Industrial Combustion

7R51. Heat Transfer in Industrial Combustion. - CE Baukal Jr (R&D Test Center, John Zink Co LLC, Tulsa OK). CRC Press, Boca Raton FL. 2000. 545 pp. ISBN 0-8493-1699-5. $89.95Reviewed by Lea-Der Chen (Dept of Mech Eng, Univ of Iowa, 2129EB, Iowa City IA 52242).This book, as stated in Preface, is intended to “fill a gap in the literature for books on heat transfer in industrial combustion, written for the practicing engineers.” This reviewer would like to congratulate the author for a well-written and a comprehensive book on industrial combustion. This book covers the three modes of heat transfer and their relevance to industrial combustion. It also covers the modeling strategies, including the thermodynamic equilibrium approximation, for example, using the robust NASA equilibrium code; correlations for heat calculation; and CFD-base multidimensional modeling. In addition, this book gives a comprehensive introduction of the experimental techniques that are important to combustion measurements. With the comprehensive review of the literature and the clear presentation of fundamentals of mass, momentum, and heat transport in combustion flames, this book should find its place as a valuable reference to practitioners in the field of combustion. As a university professor, this reviewer also finds that this book would be very useful when teaching my combustion and propulsion class (a senior-level technical elective or first-year graduate-level course). Examples from the book such as submerged burners and flame impingements will be used to illustrate the breadth and complexities of the field. There are 12 chapters, five appendices, and two indices in the book. These chapters are, in numerical order: introduction, some fundamentals of combustion, heat transfer modes, heat sources and sinks, computer modeling, experimental techniques, flame impingement, heat transfer from burners, heat transfer in furnaces, lower temperature applications, higher temperature applications, and advanced combustion systems. The Appendices are reference sources for further information on: common conversions; methods of expressing mixture ratios for CH4, C3H8, and H2; properties for CH4, C3H8, and H2 flames; fluid dynamics equations; and material properties. The book concludes with an author index and a detailed subject index. Each chapter begins with a summary of a literature review and is followed by in-depth discussion of the chapter’s subject matter. The book gives a clear link of fundamental principles to industrial combustion. At the same time, it also gives readers a working level of calculation that can be used to estimate heat transfer performance. Should the author plan a second edition of the book, perhaps it could be expanded into a handbook for heat transfer calculation for industrial combustion. In doing so, this reviewer also would like to suggest that Chapter 5 (Computer Modeling) be expanded to give more examples that can further illustrate the utilities and limitations of commercial CFD codes for heat transfer calculation of the industrial combustion examples. This reviewer recommends Heat Transfer in Industrial Combustion to his peers as well as to the libraries of institutions for higher learning.

Complex Heat Transfer in Furnaces with a Circulating Fluidized Bed

Intensity of heat transfer to screen surfaces in the furnaces with a circulating fluidized bed (CFB) is determined by both radiation and convection of particles. Due to the formation of a thermal boundary layer near the screens the role of radiation decreases and that of convection increases with an increase in concentration of particles in the furnace. Generalization of the data obtained in pilot-full-scale and industrial furnaces with a CFB allowed one to obtain a simple empirical dependence of the furnace-mean coefficient of heat transfer α (W/(m2·K) on the volumetric-mean concentration of particles c (kg/m3): α = 85·c0.3.

Analysis of spectral radiative heat transfer in furnaces using an efficient computational technique

Modeling of radiative heat transfer in participating media has significant applications in science and engineering. Neglect of scattering, emission and absorption of radiant energy by tiny particles and other gases in pulverized coal gasifiers or combustors results in serious errors in total heat flux. Recently, an efficient computational technique for solving the radiative transfer equations for the participating media has been devised (Park and Kim, JQSRT, 1997, 58(1), 115–126), which is as accurate as the S 4 method but consumes much less computer time. In the present paper, we reinterpret this new algorithm regarding its efficiency and accuracy and extend it to a realistic case where the spectral variations in the radiative properties are taken into consideration. The spectral distribution of radiation is subdivided into a finite number of bands within which the properties are assumed uniform. Solutions are found for each band employing the present technique, and are summed to obtain the total contribution. The results based on this new algorithm are benchmarked with those based on other methods such as S 4 method, and are found to be accurate as well as efficient in the cases of spectral radiative heat transfer analyses.

Numerical Simulations of Highly Preheated Air Combustion in an Industrial Furnace

The numerical simulations of reactive turbulent flows and heat transfer in an industrial slab reheat furnace in which the combustion air is highly preheated have been carried out. The influence of the ratio of the air and fuel injection velocities on the NOx production rate in the furnace has also been studied numerically. A moment closure method with the assumed β probability density function (PDF) for mixture fraction was used in the present work to model the turbulent non-premixed combustion process in the furnace. The combustion model was based on the assumption of instantaneous full chemical equilibrium. The turbulence was modeled by the standard k-ε model with a wall function. The numerical simulations have provided complete information on the flow, heat, and mass transfer in the furnace. The results also indicate that a low NOx emission and high heating efficiency can be achieved in the slab reheat furnace by using low NOx regenerative burners. It is found that the air/fuel injection velocity ratio has a strong influence on the NOx production rate in the furnace.

97/03962 One-dimensional mathematical simulation for heat transfer in furnace of pulverized coal boiler

97/03962 One-dimensional mathematical simulation for heat transfer in furnace of pulverized coal boiler