Pub Date : 2001-11-11DOI: 10.1115/imece2001/htd-24247
K. Satoh, K. T. Yang
Forest fires are of common occurrence all over the world, causing the loss of precious natural resources. The propagation of forest fires depends on many factors, notably local weather conditions. Additionally, the local terrain such as mountainous areas also plays an important role. For instance, forest fires may propagate from mountain ridges to ridges due to locally strong wind by means of firebrands and hot air flows. While much is known cm the methodologies on the forest fire control, they are largely empirical and may not be totally effective. Therefore, scientific studies based on fundamental physical understanding of the underlying phenomena are needed to provide definitive data on cause-effect relationships in various forest fire scenarios, so that the collective database can be used to suggest control strategies and preventive measures for forest fires. The present study is motivated by this approach, and specifically focuses on the phenomena of rapid forest-fire propagation from mountain slqpes to other similar mountain slopes in the direction of the wind. The study deals with both laboratory experiments and numerical simulations by the use of a CFD-based fire field model.
{"title":"Forest Fire Propagation in Inclined Terrains","authors":"K. Satoh, K. T. Yang","doi":"10.1115/imece2001/htd-24247","DOIUrl":"https://doi.org/10.1115/imece2001/htd-24247","url":null,"abstract":"\u0000 Forest fires are of common occurrence all over the world, causing the loss of precious natural resources. The propagation of forest fires depends on many factors, notably local weather conditions. Additionally, the local terrain such as mountainous areas also plays an important role. For instance, forest fires may propagate from mountain ridges to ridges due to locally strong wind by means of firebrands and hot air flows. While much is known cm the methodologies on the forest fire control, they are largely empirical and may not be totally effective. Therefore, scientific studies based on fundamental physical understanding of the underlying phenomena are needed to provide definitive data on cause-effect relationships in various forest fire scenarios, so that the collective database can be used to suggest control strategies and preventive measures for forest fires. The present study is motivated by this approach, and specifically focuses on the phenomena of rapid forest-fire propagation from mountain slqpes to other similar mountain slopes in the direction of the wind. The study deals with both laboratory experiments and numerical simulations by the use of a CFD-based fire field model.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128047562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Knowledge of the apparent radiative properties of the semitransparent hemispherical shell placed on an opaque surface is of the fundamental interest and also important to a number of application in materials processing and manufacturing ranging from metallurgical slag foaming to batch foams in glass melting to hollow bead fabrication. This paper extends our recent work [7] on using the analytical and numerical ray tracing techniques to study radiative transfer in the system described. Specifically, the local volumetric heating rate and the scattering phase function of a thin hemispherical shell exposed to incident collimated radiation are calculated both analytically and numerically, and the results are discussed in detail. To further elucidate the results, the comparison is made of the total apparent transmittance of the hemispherical shell to a plane parallel layer of semitransparent material.
{"title":"Apparent Radiative Properties and Radiation Scattering by a Semitransparent Hemispherical Shell","authors":"T. Fan, A. Fedorov","doi":"10.1115/1.1497357","DOIUrl":"https://doi.org/10.1115/1.1497357","url":null,"abstract":"\u0000 Knowledge of the apparent radiative properties of the semitransparent hemispherical shell placed on an opaque surface is of the fundamental interest and also important to a number of application in materials processing and manufacturing ranging from metallurgical slag foaming to batch foams in glass melting to hollow bead fabrication. This paper extends our recent work [7] on using the analytical and numerical ray tracing techniques to study radiative transfer in the system described. Specifically, the local volumetric heating rate and the scattering phase function of a thin hemispherical shell exposed to incident collimated radiation are calculated both analytically and numerically, and the results are discussed in detail. To further elucidate the results, the comparison is made of the total apparent transmittance of the hemispherical shell to a plane parallel layer of semitransparent material.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121612625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/htd-24242
K. Satoh, M. Shinohara, Liu Nai-an
Fire whirls have been observed in large-scale forest and city fires, which are likely accompanied by strong winds and heavy damages such as loss of lives and physical properties. Despite the general interest in the research of fire whirls, their detailed mechanisms and physical effects still remain largely unknown. One reason is that such real fire whirls are of large size and their direct studies are obviously not feasible. On the other hand, CFD-based fire field models, despite their inherent deficiencies, do provide a rational means to scale the fire sizes. It is desirable, or even necessary, to study larger-scale fire whirls with higher whirling flames in the laboratory, along with their numerical simulations. If success in the numerical simulations for the larger fire whirls can again be demonstrated, we will then approach more closely to have a quantitative tool in the use of the fire field model to simulate and study the truly large real-life fire whirls. The purpose of the present study is to attempt to create a stable six-meter class whirling flame in the laboratory, and then compare the measured data with what can be simulated with a fire field model.
{"title":"Large-Scale Laboratory Fire Whirls and Their Numerical Simulations","authors":"K. Satoh, M. Shinohara, Liu Nai-an","doi":"10.1115/imece2001/htd-24242","DOIUrl":"https://doi.org/10.1115/imece2001/htd-24242","url":null,"abstract":"\u0000 Fire whirls have been observed in large-scale forest and city fires, which are likely accompanied by strong winds and heavy damages such as loss of lives and physical properties. Despite the general interest in the research of fire whirls, their detailed mechanisms and physical effects still remain largely unknown. One reason is that such real fire whirls are of large size and their direct studies are obviously not feasible. On the other hand, CFD-based fire field models, despite their inherent deficiencies, do provide a rational means to scale the fire sizes. It is desirable, or even necessary, to study larger-scale fire whirls with higher whirling flames in the laboratory, along with their numerical simulations. If success in the numerical simulations for the larger fire whirls can again be demonstrated, we will then approach more closely to have a quantitative tool in the use of the fire field model to simulate and study the truly large real-life fire whirls. The purpose of the present study is to attempt to create a stable six-meter class whirling flame in the laboratory, and then compare the measured data with what can be simulated with a fire field model.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117342828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/htd-24245
R. Rawat, J. Spinti, Wing Yee, Philip J. Smith
In a large-scale pool fire simulation, the processes that must be modeled are complex and coupled. The flow is often highly turbulent, dynamic vortical structures are present, the chemical reactions involve several thousand elementary steps and hundreds of species/intermediates, and radiation, the dominant mode of heat transfer, is strongly affected by the presence of soot. The range of length and time scales associated with all these processes cannot be simulated on even the most powerful supercomputers available today. Our approach to making this intractable problem tractable has been twofold: one, to improve the models used at all levels in the simulation (i.e., transport models and subgrid scale models) and two, to parallelize the simulation tool to run on massively parallel machines. We have employed Large Eddy Simulation (LES) to model the fluid dynamics and the convection-diffusion scalar transport. LES successfully captures the transient nature of the coherent vortical structures present in a pool fire. We have integrated these improved models into a computational framework that provides support for parallelization. Preliminary validation results show the capability of the fire simulation tool to capture the puffing nature of pool fires. In addition, scalability studies of the simulation tool reveal close to linear scalability up to 500 processors.
{"title":"A New LES Pool Fire Simulation Tool","authors":"R. Rawat, J. Spinti, Wing Yee, Philip J. Smith","doi":"10.1115/imece2001/htd-24245","DOIUrl":"https://doi.org/10.1115/imece2001/htd-24245","url":null,"abstract":"\u0000 In a large-scale pool fire simulation, the processes that must be modeled are complex and coupled. The flow is often highly turbulent, dynamic vortical structures are present, the chemical reactions involve several thousand elementary steps and hundreds of species/intermediates, and radiation, the dominant mode of heat transfer, is strongly affected by the presence of soot. The range of length and time scales associated with all these processes cannot be simulated on even the most powerful supercomputers available today. Our approach to making this intractable problem tractable has been twofold: one, to improve the models used at all levels in the simulation (i.e., transport models and subgrid scale models) and two, to parallelize the simulation tool to run on massively parallel machines. We have employed Large Eddy Simulation (LES) to model the fluid dynamics and the convection-diffusion scalar transport. LES successfully captures the transient nature of the coherent vortical structures present in a pool fire. We have integrated these improved models into a computational framework that provides support for parallelization. Preliminary validation results show the capability of the fire simulation tool to capture the puffing nature of pool fires. In addition, scalability studies of the simulation tool reveal close to linear scalability up to 500 processors.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117343919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/htd-24227
Qing Jiang, Chao Zhang
A study of the nitrogen oxides (NOx) emission and combustion process in a gas-fired regenerative, high temperature, low emission industrial furnace has been carried out numerically. The effect of two additives, methanol (CH3OH) and hydrogen peroxide (H2O2), to fuel on the NOx emission has been studied. A moment closure method with the assumed β probability density function (PDF) for mixture fraction is used in the present work to model the turbulent non-premixed combustion process in the furnace. The combustion model is based on the assumption of instantaneous full chemical equilibrium. The results showed that CH3OH is effective in the reduction of NOx in a regenerative industrial furnace. However, H2O2 has no significant effect on the NOx emission.
{"title":"A Study of the NOx Emission in a Regenerative Industrial Furnace","authors":"Qing Jiang, Chao Zhang","doi":"10.1115/imece2001/htd-24227","DOIUrl":"https://doi.org/10.1115/imece2001/htd-24227","url":null,"abstract":"\u0000 A study of the nitrogen oxides (NOx) emission and combustion process in a gas-fired regenerative, high temperature, low emission industrial furnace has been carried out numerically. The effect of two additives, methanol (CH3OH) and hydrogen peroxide (H2O2), to fuel on the NOx emission has been studied. A moment closure method with the assumed β probability density function (PDF) for mixture fraction is used in the present work to model the turbulent non-premixed combustion process in the furnace. The combustion model is based on the assumption of instantaneous full chemical equilibrium. The results showed that CH3OH is effective in the reduction of NOx in a regenerative industrial furnace. However, H2O2 has no significant effect on the NOx emission.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129456060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/htd-24270
M. Prinkey, R. Gemmen, W. Rogers
FLUENT™, a commercial computational fluid dynamics (CFD) package, has been modified to include fuel cell electrochemistry. The model is being developed to account for three loss mechanisms present in fuel cells: ohmic overpotential, concentration overpotential, and electrochemical overpotential, each capable of temperature dependency. Because we envision this model to be applied to a wide range of geometries, the present model is also being developed to directly assess the electric potential field. This paper presents some preliminary results from the present model, and provides a summary status of our development. The main results from the present study arise from an analysis of a single monolithic SOFC geometry. Several cases were analyzed in order to generate a typical steady-state V-I curve for the cell, which summarizes its performance. Results on the detailed distribution of various conserved quantities are also presented. The preliminary results are encouraging, and show that for the geometry under study, simple scale-up relations may hold. Additionally, the newly developed tool no longer requires the modeler to manually input approximate current flow information, which will be seen to be of great benefit in fuel cell analysis.
{"title":"Application of a New CFD Analysis Tool for SOFC Technology","authors":"M. Prinkey, R. Gemmen, W. Rogers","doi":"10.1115/imece2001/htd-24270","DOIUrl":"https://doi.org/10.1115/imece2001/htd-24270","url":null,"abstract":"\u0000 FLUENT™, a commercial computational fluid dynamics (CFD) package, has been modified to include fuel cell electrochemistry. The model is being developed to account for three loss mechanisms present in fuel cells: ohmic overpotential, concentration overpotential, and electrochemical overpotential, each capable of temperature dependency. Because we envision this model to be applied to a wide range of geometries, the present model is also being developed to directly assess the electric potential field. This paper presents some preliminary results from the present model, and provides a summary status of our development.\u0000 The main results from the present study arise from an analysis of a single monolithic SOFC geometry. Several cases were analyzed in order to generate a typical steady-state V-I curve for the cell, which summarizes its performance. Results on the detailed distribution of various conserved quantities are also presented. The preliminary results are encouraging, and show that for the geometry under study, simple scale-up relations may hold. Additionally, the newly developed tool no longer requires the modeler to manually input approximate current flow information, which will be seen to be of great benefit in fuel cell analysis.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"158 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116560456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/htd-24268
Z. Ma, S. Jeter, S. Abdel-Khalik
Concern over global warming due to emission of green house gases has generated considerable interests and intensive development of fuel cells. In order to reduce the fuel cell manufacturing costs and to improve its performance and reliability, a better understanding of the fuel and oxidant species transport processes within fuel cell stack is important for fuel cell design. Fuel and oxidant stream flow distributions within a stack have significant impact on fuel cell performance and efficiency. To this end, this investigation presents the effects of the fuel and oxidant flow distributions on fuel cell stack performance with a model of fluid flow, heat and mass transfer including the electrochemical reaction, within a molten carbonate fuel cell under different gas supply conditions.
{"title":"Modeling of Transport Processes Within a Molten Carbonate Fuel Cell Stack","authors":"Z. Ma, S. Jeter, S. Abdel-Khalik","doi":"10.1115/imece2001/htd-24268","DOIUrl":"https://doi.org/10.1115/imece2001/htd-24268","url":null,"abstract":"\u0000 Concern over global warming due to emission of green house gases has generated considerable interests and intensive development of fuel cells. In order to reduce the fuel cell manufacturing costs and to improve its performance and reliability, a better understanding of the fuel and oxidant species transport processes within fuel cell stack is important for fuel cell design. Fuel and oxidant stream flow distributions within a stack have significant impact on fuel cell performance and efficiency. To this end, this investigation presents the effects of the fuel and oxidant flow distributions on fuel cell stack performance with a model of fluid flow, heat and mass transfer including the electrochemical reaction, within a molten carbonate fuel cell under different gas supply conditions.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131638072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/htd-24244
K. Wakatsuki, B. Ringwelski, J. Quintiere
The fire behavior of heptane burning in a poorly ventilated compartment was studied. The diameter of the heptane pan fires were varied and the ventilation opening size and location were adjusted. Two kinds of compartment fire experiment were conducted: (1) horizontal slits at the top and bottom of a wall, and (2) a single vent at the roof. Temperature, oxygen, fuel mass loss rate and differential pressure were measured. Extinction was studied with an oxygen meter to find the minimum oxygen concentration in the compartment achieved in ventilation-controlled fires. Extinguishments due to ventilation or complete fuel consumption was distinguished. Flow exchange was measured by differential pressure transducers. Particularly, flow exchange of ceiling vent was examined by calculation of flooding pressure difference, which will allow bi-directional flow. The wall vent case had oscillatory combustion (puffing), which sometimes leads to an increase in fire amplitude followed by extinction. This was not observed for the ceiling vent case. Video recording of the flame was conducted through a glass on sidewall. The fire behavior varied from conditions in which the flame extinguishes to cases of steady burning. In some cases, “ghosting flames” were observed.
{"title":"Fire Behavior in a Poorly Ventilated Compartment","authors":"K. Wakatsuki, B. Ringwelski, J. Quintiere","doi":"10.1115/imece2001/htd-24244","DOIUrl":"https://doi.org/10.1115/imece2001/htd-24244","url":null,"abstract":"\u0000 The fire behavior of heptane burning in a poorly ventilated compartment was studied. The diameter of the heptane pan fires were varied and the ventilation opening size and location were adjusted. Two kinds of compartment fire experiment were conducted: (1) horizontal slits at the top and bottom of a wall, and (2) a single vent at the roof. Temperature, oxygen, fuel mass loss rate and differential pressure were measured. Extinction was studied with an oxygen meter to find the minimum oxygen concentration in the compartment achieved in ventilation-controlled fires. Extinguishments due to ventilation or complete fuel consumption was distinguished. Flow exchange was measured by differential pressure transducers. Particularly, flow exchange of ceiling vent was examined by calculation of flooding pressure difference, which will allow bi-directional flow. The wall vent case had oscillatory combustion (puffing), which sometimes leads to an increase in fire amplitude followed by extinction. This was not observed for the ceiling vent case. Video recording of the flame was conducted through a glass on sidewall. The fire behavior varied from conditions in which the flame extinguishes to cases of steady burning. In some cases, “ghosting flames” were observed.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126524435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The self-preserving properties of round nonbuoyant turbulent starting jets, puffs and interrupted jets were studied experimentally and theoretically for flows in still and unstratified environments. The experiments involved dye-containing fresh water sources injected into still fresh water within a large fresh water tank with images of the flows obtained using a video camera. Near-source behavior varied significantly with source properties but self-preserving behavior was observed at distances greater than 20–30 source diameters from the source. Within the self-preserving region, normalized streamwise and radial penetration distances varied as functions of time, in accord with requirements for self-preservation, to the following powers: 1/2 for starting nonbuoyant jets and 1/4 for nonbuoyant puffs. Effects of injected fluid quantity for puffs were reflected by the location of the virtual origin which was independent of injected fluid volume for small volumes but became proportional to injected fluid volume for large volumes typical of interrupted jets.
{"title":"Self-Preserving Properties of Unsteady Round Nonbuoyant Turbulent Starting Jets and Puffs in Still Fluids","authors":"R. Sangras, O. Kwon, G. Faeth","doi":"10.1115/1.1421047","DOIUrl":"https://doi.org/10.1115/1.1421047","url":null,"abstract":"\u0000 The self-preserving properties of round nonbuoyant turbulent starting jets, puffs and interrupted jets were studied experimentally and theoretically for flows in still and unstratified environments. The experiments involved dye-containing fresh water sources injected into still fresh water within a large fresh water tank with images of the flows obtained using a video camera. Near-source behavior varied significantly with source properties but self-preserving behavior was observed at distances greater than 20–30 source diameters from the source. Within the self-preserving region, normalized streamwise and radial penetration distances varied as functions of time, in accord with requirements for self-preservation, to the following powers: 1/2 for starting nonbuoyant jets and 1/4 for nonbuoyant puffs. Effects of injected fluid quantity for puffs were reflected by the location of the virtual origin which was independent of injected fluid volume for small volumes but became proportional to injected fluid volume for large volumes typical of interrupted jets.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133552446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/htd-24229
B. Adams, David H. Wang
A DOE-funded program was used to understand the mechanisms that control the formation of NOx during the combustion of steelmaking by-product fuels and to investigate possible low-cost control options to minimize the NOx emissions. This paper discusses the CFD modeling results of NOx emissions in a reheat furnace. The reheat furnace has a total of 20 burners distributed over three firing zones. The furnace is fired at a rate of 250 × 106 Btu/hr and an overall stoichiometric ratio of 1.06 (fuel lean). Fuels with heating values of approximate 500 Btu/SCF were examined, including coke oven gas (COG), blast furnace gas (BFG) and a blend of COG, BFG, natural gas (NG) and nitrogen. A good range of process variables was modeled to examine effects of fuel type, air preheat, stoichiometric ratio, firing rate and burner stoichiometry distribution on NOx emissions. Modeling results indicated that NOx formation in the reheat furnace is dominated by thermal NO, with some variation depending on the fuel fired. Temperature profiles showed an effective separation of the furnace interior into top and bottom zones as a result of the steel slab barrier. Higher temperatures characterized the bottom zone and elevated NOx levels as a result of the confined space and enhanced fuel air mixing provided by the slab supports. Results also showed that reburning of NOx plays a significant role in final NOx emissions with 30–40% of NOx formed being reduced by reburning in most cases. Modeling identified that operating the side burners in each burner zone slightly substoichiometric (while maintaining the overall furnace stoichiometry at 1.06) provided significant NOx reduction via reburning. NOx reductions of 23% and 30% were predicted when firing with COG and COG-NG-Air fuels, respectively. Overall furnace exit temperatures and heat flux profiles were not significantly affected by the biased firing.
美国能源部资助的一个项目用于了解炼钢副产品燃料燃烧过程中控制氮氧化物形成的机制，并研究可能的低成本控制方案，以最大限度地减少氮氧化物排放。本文讨论了加热炉内NOx排放的CFD模拟结果。加热炉共有20个燃烧器，分布在三个燃烧区。炉的燃烧速率为250 × 106 Btu/hr，总化学计量比为1.06(燃料稀薄)。研究人员检测了热值约为500 Btu/SCF的燃料，包括焦炉煤气(COG)、高炉煤气(BFG)以及焦炉煤气、BFG、天然气(NG)和氮气的混合物。模拟了一系列过程变量，以检验燃料类型、空气预热、化学计量比、燃烧速率和燃烧器化学计量分布对NOx排放的影响。模拟结果表明，再加热炉内NOx的生成以热NO为主，并随燃料的不同而有一定的变化。温度分布表明，由于钢坯屏障，炉内有效地分离为顶部和底部区域。由于平板支架提供的密闭空间和增强的燃料空气混合，底部区域温度较高，NOx水平升高。结果还表明，NOx的再燃烧在最终NOx排放中起着重要作用，在大多数情况下，再燃烧减少了30-40%的NOx生成。建模表明，在每个燃烧器区域操作侧燃烧器的化学计量值略低于1.06(同时保持整个炉的化学计量值为1.06)，通过再燃烧可以显著减少NOx。在使用COG和COG- ng - air燃料时，预计氮氧化物排放量分别减少23%和30%。总体炉膛出口温度和热流密度分布不受偏烧的显著影响。
{"title":"NOx Emissions in a Steel Reheat Furnace Firing By-Product Fuels","authors":"B. Adams, David H. Wang","doi":"10.1115/imece2001/htd-24229","DOIUrl":"https://doi.org/10.1115/imece2001/htd-24229","url":null,"abstract":"\u0000 A DOE-funded program was used to understand the mechanisms that control the formation of NOx during the combustion of steelmaking by-product fuels and to investigate possible low-cost control options to minimize the NOx emissions. This paper discusses the CFD modeling results of NOx emissions in a reheat furnace. The reheat furnace has a total of 20 burners distributed over three firing zones. The furnace is fired at a rate of 250 × 106 Btu/hr and an overall stoichiometric ratio of 1.06 (fuel lean). Fuels with heating values of approximate 500 Btu/SCF were examined, including coke oven gas (COG), blast furnace gas (BFG) and a blend of COG, BFG, natural gas (NG) and nitrogen. A good range of process variables was modeled to examine effects of fuel type, air preheat, stoichiometric ratio, firing rate and burner stoichiometry distribution on NOx emissions.\u0000 Modeling results indicated that NOx formation in the reheat furnace is dominated by thermal NO, with some variation depending on the fuel fired. Temperature profiles showed an effective separation of the furnace interior into top and bottom zones as a result of the steel slab barrier. Higher temperatures characterized the bottom zone and elevated NOx levels as a result of the confined space and enhanced fuel air mixing provided by the slab supports. Results also showed that reburning of NOx plays a significant role in final NOx emissions with 30–40% of NOx formed being reduced by reburning in most cases. Modeling identified that operating the side burners in each burner zone slightly substoichiometric (while maintaining the overall furnace stoichiometry at 1.06) provided significant NOx reduction via reburning. NOx reductions of 23% and 30% were predicted when firing with COG and COG-NG-Air fuels, respectively. Overall furnace exit temperatures and heat flux profiles were not significantly affected by the biased firing.","PeriodicalId":426926,"journal":{"name":"Heat Transfer: Volume 4 — Combustion and Energy Systems","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123237529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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