The soot formation model based on inverse ethylene diffusion flames was performed to study the sensitivity of the soot formation process to the prediction results.The effects of efficiency parameters such as soot ince...The soot formation model based on inverse ethylene diffusion flames was performed to study the sensitivity of the soot formation process to the prediction results.The effects of efficiency parameters such as soot inception,surface growth and coagulation on the simulation results were studied by using the adjustable efficiency model.In addition,the reversible soot model and conjugate heat transfer(CHT)model were also introduced to explore their advantages.Results indicated that,among adjustable efficiency parameters,the nucleation efficiency had the greatest influence on the predicted soot and PAHs distributions,while the Habstraction-C2H2-addition(HACA)process and PAH adsorption surface growth efficiencies impacted little.The adjustable efficiency parameters had a significant effect on the concentration of soot gaseous precursors and soot particles,but their effects on temperature,gas phase molecules,and intermediate species were not obvious.When the nucleation efficiency increased from 2×10^(-6)to 1×10^(-4),the predicted value of the integrated soot was increased by nearly 50%,and the maximum primary particle number density and the number of aggregates were increased by an order of magnitude.The maximum concentration of BAPYR was doubled.However,the peak temperature along the axial direction increased by only 3.5 K.Using the reversible soot model,the approximation results of the adjustable efficiency parameters could be modified,which showed the feasibility of the model.The use of the CHT model promoted pyrolysis of the fuel below the outlet of the fuel tube,with high-temperature zones,soot zones,and PAHs zones moving towards higher flame heights.Besides,when using the reversible model and the CHT model,the maximum soot volume fraction decreased by 39%compared with the basic efficiency parameters,while the concentration of BAPYR increased by 162%,and the concentrations of gas phase species were decreased.展开更多
Soot emissions (PM 2.5) from land-based sources pose a substantial health risk, and now are subject to new and tougher EPA regulations. Flaring produces significant amount of particulate matter in the form of soot, al...Soot emissions (PM 2.5) from land-based sources pose a substantial health risk, and now are subject to new and tougher EPA regulations. Flaring produces significant amount of particulate matter in the form of soot, along with other harmful gas emissions. A few experimental studies have previously been done on flames burning in a controlled condition. In these lab-experiments, great effort is needed to collect, sample, and analyze the soot so that the emission rate can be calculated. Soot prediction in flares is tricky due to variable conditions such as radiation and surrounding air available for combustion. Work presented in this paper simulates some lab-scale flares in which soot yield for methane flame mixture was measured under different conditions. The focus of this paper is on soot modeling with various flair operating conditions. The computational fluid dynamics software ANSYS Fluent 13 is used. Different soot models were explored along with other chemistry mechanisms. The effect of radiation models, quantity of air supplied, different fuel mixture and its effect over soot formations were also studied.展开更多
The serious carbon deposition existing in catalytic partial oxidation of methane(CPOM) to syngas process is one of the key problems that impede its industrialization. In this study, 3-dimensional unsteady numerical si...The serious carbon deposition existing in catalytic partial oxidation of methane(CPOM) to syngas process is one of the key problems that impede its industrialization. In this study, 3-dimensional unsteady numerical simulations of the soot formation and oxidation in oxidation section in a heat coupling reactor were carried out by computational fluid dynamics(CFD) approach incorporating the Moss-Brookes model for soot formation. The model has been validated and proven to be in good agreement with experiment results. Effects of nozzle type,nozzle convergence angle, channel spacing, number of channels, radius/height ratio, oxygen/carbon ratio, preheat temperature and additional introduction of steam on the soot formation were simulated. Results show that the soot formation in oxidation section of the heat coupling reactor depends on both nozzle structures and operation conditions, and the soot concentration can be greatly reduced by optimization with the maximum mass fraction of soot inside the oxidation reactor from 2.28% to 0.0501%, and so that the soot mass fraction at the exit reduces from0.74% to 0.03%.展开更多
As rapid development of economy and acceleration of urbanization process, air pollution problem in Chongqing was more and more prominent. By referring to statistical yearbook and investigating energy usage and economy...As rapid development of economy and acceleration of urbanization process, air pollution problem in Chongqing was more and more prominent. By referring to statistical yearbook and investigating energy usage and economy activity levels of various industrial sectors of Chongqing, basic data （activity level, energy production and consumption situation） of various economic sectors of Chongqing during 2007 -2012 were ob- tained. Using emission coefficient method, soot emission inventory in Chongqing during 2007 -2012 was established. Meanwhile, input-output model containing environmental factor was established to study relationship between economy development and environmental protection and number relationship between economy development and pollutant emission. According to the results, countermeasures of emission reduction in Chongqing were put forward.展开更多
We present a unique approach for communication deadlock analysis for actor-model which has an under-approximated analysis result. Our analysis detects narrowly defined communication deadlocks by finding a cyclic depen...We present a unique approach for communication deadlock analysis for actor-model which has an under-approximated analysis result. Our analysis detects narrowly defined communication deadlocks by finding a cyclic dependency relation in a novel dependency graph called the slave dependency graph. The slave dependency graph is based on a new relationship between Actors, slave dependency, defined by us. After that, we implement this theory in Soot, an analysis tool for Java, and use it to analyze actor-based Java program realized by Akka, a Java library that allows actor-based programming. We argue that our analysis can detect a specific kind of communication deadlock with the precise result, but has many limitations.展开更多
基金supported by the Jiangsu Provincial Natural Science Foundation of China(Grant No.BK20220955)the National Natural Science Foundation of China(Grant No.52076110)+1 种基金China Postdoctoral Science Foundation(Grant No.2021M701719)the Fundamental Research Funds for the Central Universities(Grant No.30922010409)。
文摘The soot formation model based on inverse ethylene diffusion flames was performed to study the sensitivity of the soot formation process to the prediction results.The effects of efficiency parameters such as soot inception,surface growth and coagulation on the simulation results were studied by using the adjustable efficiency model.In addition,the reversible soot model and conjugate heat transfer(CHT)model were also introduced to explore their advantages.Results indicated that,among adjustable efficiency parameters,the nucleation efficiency had the greatest influence on the predicted soot and PAHs distributions,while the Habstraction-C2H2-addition(HACA)process and PAH adsorption surface growth efficiencies impacted little.The adjustable efficiency parameters had a significant effect on the concentration of soot gaseous precursors and soot particles,but their effects on temperature,gas phase molecules,and intermediate species were not obvious.When the nucleation efficiency increased from 2×10^(-6)to 1×10^(-4),the predicted value of the integrated soot was increased by nearly 50%,and the maximum primary particle number density and the number of aggregates were increased by an order of magnitude.The maximum concentration of BAPYR was doubled.However,the peak temperature along the axial direction increased by only 3.5 K.Using the reversible soot model,the approximation results of the adjustable efficiency parameters could be modified,which showed the feasibility of the model.The use of the CHT model promoted pyrolysis of the fuel below the outlet of the fuel tube,with high-temperature zones,soot zones,and PAHs zones moving towards higher flame heights.Besides,when using the reversible model and the CHT model,the maximum soot volume fraction decreased by 39%compared with the basic efficiency parameters,while the concentration of BAPYR increased by 162%,and the concentrations of gas phase species were decreased.
文摘Soot emissions (PM 2.5) from land-based sources pose a substantial health risk, and now are subject to new and tougher EPA regulations. Flaring produces significant amount of particulate matter in the form of soot, along with other harmful gas emissions. A few experimental studies have previously been done on flames burning in a controlled condition. In these lab-experiments, great effort is needed to collect, sample, and analyze the soot so that the emission rate can be calculated. Soot prediction in flares is tricky due to variable conditions such as radiation and surrounding air available for combustion. Work presented in this paper simulates some lab-scale flares in which soot yield for methane flame mixture was measured under different conditions. The focus of this paper is on soot modeling with various flair operating conditions. The computational fluid dynamics software ANSYS Fluent 13 is used. Different soot models were explored along with other chemistry mechanisms. The effect of radiation models, quantity of air supplied, different fuel mixture and its effect over soot formations were also studied.
基金supported by the National Science Foundation of China under Grant No.20776156 and No.21176256the Science Foundation ofChina University of Petroleum,Beijing(No.KYJJ2012-03-01)
文摘The serious carbon deposition existing in catalytic partial oxidation of methane(CPOM) to syngas process is one of the key problems that impede its industrialization. In this study, 3-dimensional unsteady numerical simulations of the soot formation and oxidation in oxidation section in a heat coupling reactor were carried out by computational fluid dynamics(CFD) approach incorporating the Moss-Brookes model for soot formation. The model has been validated and proven to be in good agreement with experiment results. Effects of nozzle type,nozzle convergence angle, channel spacing, number of channels, radius/height ratio, oxygen/carbon ratio, preheat temperature and additional introduction of steam on the soot formation were simulated. Results show that the soot formation in oxidation section of the heat coupling reactor depends on both nozzle structures and operation conditions, and the soot concentration can be greatly reduced by optimization with the maximum mass fraction of soot inside the oxidation reactor from 2.28% to 0.0501%, and so that the soot mass fraction at the exit reduces from0.74% to 0.03%.
基金Supported by Municipal Key Laboratory Project of Chongqing HigherSchool,China(WEPKL2013MS-10)National Innovation and Entre-preneurship Training Program of University Student in 2013,China(201310643003)
文摘As rapid development of economy and acceleration of urbanization process, air pollution problem in Chongqing was more and more prominent. By referring to statistical yearbook and investigating energy usage and economy activity levels of various industrial sectors of Chongqing, basic data （activity level, energy production and consumption situation） of various economic sectors of Chongqing during 2007 -2012 were ob- tained. Using emission coefficient method, soot emission inventory in Chongqing during 2007 -2012 was established. Meanwhile, input-output model containing environmental factor was established to study relationship between economy development and environmental protection and number relationship between economy development and pollutant emission. According to the results, countermeasures of emission reduction in Chongqing were put forward.
文摘We present a unique approach for communication deadlock analysis for actor-model which has an under-approximated analysis result. Our analysis detects narrowly defined communication deadlocks by finding a cyclic dependency relation in a novel dependency graph called the slave dependency graph. The slave dependency graph is based on a new relationship between Actors, slave dependency, defined by us. After that, we implement this theory in Soot, an analysis tool for Java, and use it to analyze actor-based Java program realized by Akka, a Java library that allows actor-based programming. We argue that our analysis can detect a specific kind of communication deadlock with the precise result, but has many limitations.
