In this study, the effects of particle size distribution （PSD）, chemical composition and pore structure of petroleum coke on the slurryability of petroleum coke water slurry （PCWS） were investigated. Four petroleu...In this study, the effects of particle size distribution （PSD）, chemical composition and pore structure of petroleum coke on the slurryability of petroleum coke water slurry （PCWS） were investigated. Four petroleum cokes were studied, and they showed completely different slurryability. The solid concentration at fixed viscosity （i.e. apparent viscosity of 1000 mPa） （SCFV） of four PCWSs is different from each other, with the highest value of 70.9%, and lowest of 62.1%. The apparent viscosity of the four PCWSs all increased with an increase of the solid concentration. The results showed that the PSD, inherent moisture content, specific surface area and pore volume of petroleum coke were key factors to affect the slurryability. The slurryability was enhanced with increasing PSD range and particle packing fraction, and with decreasing inherent moisture content, specific surface area and pore volume.展开更多
NiO and Ce0.8Sm0.2O1.9 were synthesized by the combination of sol gel and citric acid-nitrate low temperature self-propagating combustion method. Anode precursors which include home-made NiO and Ce0.8Sm0.2O1.9 were pr...NiO and Ce0.8Sm0.2O1.9 were synthesized by the combination of sol gel and citric acid-nitrate low temperature self-propagating combustion method. Anode precursors which include home-made NiO and Ce0.8Sm0.2O1.9 were prepared by different NiO content and fabrication condition. The anode precursors with pure hydrogen at 820 ℃ for 2.5 h were reduced, The electrical conductivity was tested, and the effect of microstructure on electrical conductivity of Ce0.8Sm0.2O1.9 composite anodes was investigated. The results show that the anode electrical conductivity depends strongly on the anode microstructure that is dramatically affected by Ni content and fabrication condition.展开更多
Compositely doped oxide La0.5Sr0.5CoO2.91 （LSC） was synthesized using solid state reaction and citric acid-nitrate low temperature self-propagating combustion methods. The crystal structure and the particle size mic...Compositely doped oxide La0.5Sr0.5CoO2.91 （LSC） was synthesized using solid state reaction and citric acid-nitrate low temperature self-propagating combustion methods. The crystal structure and the particle size micrograph of LSC powders synthesized by different methods were investigated with XRD and SEM. The experimental results show that the single perovskite phase of LSC can be synthesized by solid state reaction method, but LaSrCoO4 phase appears in LSC powder synthesized by citric acid-nitrate low temperature self-propagating combustion method. The LSC particle by citric acid-nitrate low temperature self- propagating combustion method has smaller size. To analyze the character of cathode material based on Ceo.gGdo.101.95（GDC） electrolyte, two types of cathode wafers were fabricated with the two kinds of LSC and GDC powders at the mass rate of 6：4, respectively. The electrical conductivity of the sintered samples was measured by four probe DC method from 300 to 800 ℃. The cathode with LSC particle by citric acid- nitrate low temperature self-propagating combustion method has higher electrical conductivity. In order to investigate the stability, the two samples were put into the muffle furnace to heat up in air at 800℃for 800 h. To analysis the reason for reduced electrical conductivity, the crystal structure and the particle micrograph of the cathode wafers before and after an exposure were investigated with XRD and SEM. The result shows that new crystal structure appears in both the two kinds of cathode wafers and crystal micrographs change a lot.展开更多
Lean premixed flame characteristics of several typical low calorific value (LCV) syngases (basis CO/H2/CH4/CO2/N2),including bituminous coal,wood residue,corn core,and wheat straw gasification syngas,were investigated...Lean premixed flame characteristics of several typical low calorific value (LCV) syngases (basis CO/H2/CH4/CO2/N2),including bituminous coal,wood residue,corn core,and wheat straw gasification syngas,were investigated using OH planar laser induced fluorescence (PLIF) technology.OH radical distributions within the turbulent flame were measured for different turbulence intensities.Flame structures of syngases were analyzed and characterized with respect to burnt and unburnt regions,flame curvature (sharp cusp),local extinction (holes and penetration),OH reaction layer thickness,wrinkling,and other features,with OH-PLIF instantaneous images and statistical analysis.Results show that H2 content,LCV,and turbulence intensity are the most effective factors influencing the OH radical intensity and thickness of OH radical layers.The bituminous coal gasification syngas with relatively higher LCV and H2 content tends to burn out easily.Through changes in thickness of the OH radical layers and signal intensities,the reaction layer can be compressed by intensifying turbulence and thereby the combustion processes of syngas.展开更多
In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocollo...In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocolloid viscosity.Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion.The fractal concept is introduced to describe the irregular and dynamic aggregate structure.The structure of aggregates,which is considered to play an important role in viscosity,is affected by both intermolecular and electrostatic forces.The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction.The aggregate structure is also affected by the pH of the solution.Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force,the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure.展开更多
Large-eddy simulation(LES) with fully resolved rotor method(FRM) is applied to explore the turbulent wake flow characteristics and vortex evolution laws of a two-bladed horizontal-axis wind turbine. Relevant wind tunn...Large-eddy simulation(LES) with fully resolved rotor method(FRM) is applied to explore the turbulent wake flow characteristics and vortex evolution laws of a two-bladed horizontal-axis wind turbine. Relevant wind tunnel experiments have been done based on time resolved particle image velocimetry(TRPIV) technique. The simulation results are validated by the experimental data and they are in good agreement. The axial average velocity, turbulent kinetic energy, shear Reynolds stress, and vortex structure of the wind turbine wake are analyzed based on the comparison of LES results and experimental data. It is observed that the wake diameter of wind turbine enlarges with the increase of tip speed ratio(TSR). Turbulent kinetic energy meets its minimum value when x/R=2.0. Shear Reynolds stress appears a positive peak in the near wake when x/R<2.0, and the value of shear Reynolds stress decreases along the axial direction. The blade tip vortex dissipates more quickly than the central vortex in the wind turbine wake, and the gradient of the relationship curve between the blade tip vortex core position and the vortex age decreases as the TSR increases. With the increase of TSR, the thrust coefficient increases, and the power coefficient increases first and then decreases.The present work proves that LES with FRM could calculate wind turbine turbulent wake flow with a high accuracy.展开更多
In order to eliminate secondary pollution caused by municipal solid waste(MSW)incineration,a MSW gasification and melting process is proposed.The process is expected to reduce the emission of pollutants,especially hea...In order to eliminate secondary pollution caused by municipal solid waste(MSW)incineration,a MSW gasification and melting process is proposed.The process is expected to reduce the emission of pollutants,especially heavy-metals and dioxins.In this paper,the combustible components of MSW and simulated MSW were gasified in a lab-scale fluidized bed at 400°C-700°C when the excess air ratio(ER)was between 0.2 and 0.8.The experimental results indicated that the MSW could be gasified effectively in a fluidized bed at approximately 600°C-700°C when excess air ratio was 0.2-0.4.The melting characteristics of two typical fly ash samples from MSW incinerators were investigated.The results indicated that fly ash of pure MSW incineration could be melted at approximately 1,300°C and that of MSW and coal co-combustion could be melted at approximately 1,400°C.When temperature was over 1,100°C,more than 99.9%of the dioxins could be decomposed and most of the heavy-metals could be solidified in the slag.Based on the above experiments,two feasible MSW gasification and mel-ting processes were proposed for low calorific value MSW:(1)sieved MSW gasification and melting system,which was based on an idea of multi-recycle;(2)gasification and melting scheme of MSW adding coal as assistant fuel.展开更多
The analysis of microstructure and polymeriza-tion degree showed that acid wash altered the cellulose morphology and decreased the polymerization degree signifi-cantly.A series of experiments were done to study the ef...The analysis of microstructure and polymeriza-tion degree showed that acid wash altered the cellulose morphology and decreased the polymerization degree signifi-cantly.A series of experiments were done to study the effect of acid wash on cellulose rapid pyrolysis.Experimental results showed that under acid pretreatment,the yield of bio-oil decreased while the production of gas and char increased.With an increase in acid concentration,this trend would be further enhanced.Sulphuric acid limited the formation of bio-oil more effectively than hydrochloric acid and pho-sphoric acid.According to the GC-MS analysis of bio-oil,high-concentration acid wash restrained the formation of levoglucosan by catalyzing dehydration process and cross linking reaction.展开更多
The leakage accident of molten salt in the thermal storage tank will cause the shutdown and enormous economic losses of Concentrated Solar Power plants.This study investigates the heat transfer and flow characteristic...The leakage accident of molten salt in the thermal storage tank will cause the shutdown and enormous economic losses of Concentrated Solar Power plants.This study investigates the heat transfer and flow characteristic of commercial molten nitrates leaking in the thermal state porous foundation material.The migration width and depth of three molten nitrates,Solar Salt(60 wt%NaNO_(3)-40 wt%KNO_(3)),Hitec XL(7 wt%NaNO_(3)-45 wt%KNO_(3)-48 wt%Ca(NO_(3))_(2))and Hitec(7 wt%NaNO_(3)-53 wt%KNO_(3)-40 wt%NaNO_(2)),are obtained at different operating temperatures.Experimental results indicate that the temperature rising rate of foundation material in the nitrate leaking process has a trend of first increasing rapidly and then decreasing,and then it increases slightly as the depth increases.The temperature rising rate increases obviously with increasing operating temperature of the molten salt.With the increase of the operating temperature,the distances from the storage tank bottom to solid salt in foundation and the total migration depths both increase obviously,while the average migrating widths change slightly.At the same operating temperature,the temperature rising rate of the foundation material where Hitec XL and Hitec salt leak is significantly greater than that with Solar Salt,which is closely related to the melting points of molten salts.The migration depth of Hitec is 95.03%greater than that of Solar Salt and 19.11%larger than that of Hitec XL at the operating temperature of 300℃.Compared with Hitec XL,the leakage of Hitec with a smaller viscosity has a larger temperature rising rate and a wider and deeper transporting range during the leakage process.This work could guide the installation locations of the leak detection devices for high temperature storage tank and the environmental treatment of leaking accident.展开更多
Pyrolysis was carried out in an entrained flow drop-tube furnace（DTF） and tube furnace（TF） using Pingzhuang lignite coal with various catalyst concentrations（2 wt%, 4 wt%, and 6 wt%） of KCl and CaCl2 for the syn...Pyrolysis was carried out in an entrained flow drop-tube furnace（DTF） and tube furnace（TF） using Pingzhuang lignite coal with various catalyst concentrations（2 wt%, 4 wt%, and 6 wt%） of KCl and CaCl2 for the syngas component at 800°C–1200°C. Five catalysts（KCl, CaCl2, NiCl2, MnCl2, and ZnCl2） at 6 wt% were chosen for DTF at 800°C–1200°C. An online gas chromatograph analyzer and the Fourier transform infrared spectra were used for the analysis of the syngas and char structure. Results showed that the overall CO2 and CH4 content in DTF was lower than that in TF, mainly due to the CH4 carbon reaction at high temperature. Moreover, the CO% in DTF was higher than in the TF experiment, as char reacts with carbon dioxide to form carbon monoxide. In DTF experiment, the maximum and minimum CO2 content was 15.20% with 6 wt% Mn at 800°C and 0.33% with 6 wt% K at 1100°C, respectively. The maximum CO% was found in raw coal. Concentrations of Mn2+, Zn2+, and K+can significantly increase H2%, whereas Ca2+ and Ni2+ have a minor effect on H2%; however, the overall presence of catalyst has a positive impact on the H2 content.展开更多
A novel method to apply artificial neural network (ANN) for both chemical kinetics reduction and source term evaluation is introduced and tested in direct numerical simulation (DNS) and large eddy simulation (LES) of ...A novel method to apply artificial neural network (ANN) for both chemical kinetics reduction and source term evaluation is introduced and tested in direct numerical simulation (DNS) and large eddy simulation (LES) of reactive flows. To gather turbulence affected flame data for ANN training, a new computation-economical method, called 1D pseudo-velocity disturbed flame (PVDF), is developed and used to generate thermo-chemical states independent of the modeled flame. Then a back-propagation ANN is trained using scaled conjugate gradient algorithm to memorize the sample states with reduced orders. The new method is employed in DNS and LES modeling of H2 /air and C3H8 /air premixed flames experiencing various levels of turbulence. The test result shows that compared to traditional computation with full mechanism and direct integration, this method can obtain quite large speed-ups with adequate prediction accuracy.展开更多
The main objective of this article was to experimentally investigate the dynamic response of diffusion flame under acoustic excitation in a laboratory-scale burner.Two parametric variations of the burner,the burner in...The main objective of this article was to experimentally investigate the dynamic response of diffusion flame under acoustic excitation in a laboratory-scale burner.Two parametric variations of the burner,the burner inlet length and variation of the airflow rate,were studied.Experimental results were analyzed through nonlinear time series analysis and several resonance characteristics were obtained.Results indicate that the flame-acoustic resonance only appears under certain frequencies together with the fuel tube vibration.Resonance characteristics of the combustion chamber and air inlet in the non-premixed burner indicate quasi-periodic or limit cycle oscillations,respectively.Flame-acoustic resonance would trigger the frequency and amplitude mode-transition in burners.Moreover,the intermittency of flame heat release was observed under variation of inlet length and airflow rate in the burner;the 445 mm case shows more frequency peaks and fluctuations than the 245 mm one.Four typical flame forms were examined during the flame-acoustic resonance conditions,evolves from wrinkled flames to diverged flames,then evolves to reattached flames and finally to blow-off flames.This study proposed the practical application of nonlinear time-series analysis method as a detection tool for flame-acoustic resonance in laboratory non-premixed burners,which could contribute to the detection and prevention of potential thermoacoustic instabilities or resonance structure failures of industrial boilers.Finally,this study demonstrates an alternative to conventional linear tool for the characterization of nonlinear acoustic resonance in industrial boilers.展开更多
Two-flux method can be used, as a simplification for the radiative heat transfer, to predict heat flux in a slab consisting of gas and particles. In the original two-flux method (Schuster, 1905 and Schwarzschild, 1906...Two-flux method can be used, as a simplification for the radiative heat transfer, to predict heat flux in a slab consisting of gas and particles. In the original two-flux method (Schuster, 1905 and Schwarzschild, 1906), the radiation field was assumed to be isotropic. But for gas-particles mixture in combustion environments, the scatterings of particles are usually anisotropic, and the original two-flux method gives critical errors when ignoring this anisotropy. In the present paper, a multilayer four-flux model developed by Rozé et al. (2001) is extended to calculate the radiation heat flux in a slab containing participating particles and gas mixture. The analytic resolution of the radiative transfer equation in the framework of a two-flux approach is presented. The average crossing parameter ε and the forward scattering ratio ζ are defined to describe the anisotropy of the radiative field. To validate the model, the radiation transfer in a slab has been computed. Comparisons with the exact analytical result of Modest (1993) and the original two-flux model show the exactness and the improvement. The emissivity of a slab containing flyash/CO2/H2O mixture is obtained using the new model. The result is identical with that of Goodwin (1989).展开更多
基金the financial support from National Key Basic Research Program Project (No. 2010CB227001)
文摘In this study, the effects of particle size distribution （PSD）, chemical composition and pore structure of petroleum coke on the slurryability of petroleum coke water slurry （PCWS） were investigated. Four petroleum cokes were studied, and they showed completely different slurryability. The solid concentration at fixed viscosity （i.e. apparent viscosity of 1000 mPa） （SCFV） of four PCWSs is different from each other, with the highest value of 70.9%, and lowest of 62.1%. The apparent viscosity of the four PCWSs all increased with an increase of the solid concentration. The results showed that the PSD, inherent moisture content, specific surface area and pore volume of petroleum coke were key factors to affect the slurryability. The slurryability was enhanced with increasing PSD range and particle packing fraction, and with decreasing inherent moisture content, specific surface area and pore volume.
文摘NiO and Ce0.8Sm0.2O1.9 were synthesized by the combination of sol gel and citric acid-nitrate low temperature self-propagating combustion method. Anode precursors which include home-made NiO and Ce0.8Sm0.2O1.9 were prepared by different NiO content and fabrication condition. The anode precursors with pure hydrogen at 820 ℃ for 2.5 h were reduced, The electrical conductivity was tested, and the effect of microstructure on electrical conductivity of Ce0.8Sm0.2O1.9 composite anodes was investigated. The results show that the anode electrical conductivity depends strongly on the anode microstructure that is dramatically affected by Ni content and fabrication condition.
文摘Compositely doped oxide La0.5Sr0.5CoO2.91 （LSC） was synthesized using solid state reaction and citric acid-nitrate low temperature self-propagating combustion methods. The crystal structure and the particle size micrograph of LSC powders synthesized by different methods were investigated with XRD and SEM. The experimental results show that the single perovskite phase of LSC can be synthesized by solid state reaction method, but LaSrCoO4 phase appears in LSC powder synthesized by citric acid-nitrate low temperature self-propagating combustion method. The LSC particle by citric acid-nitrate low temperature self- propagating combustion method has smaller size. To analyze the character of cathode material based on Ceo.gGdo.101.95（GDC） electrolyte, two types of cathode wafers were fabricated with the two kinds of LSC and GDC powders at the mass rate of 6：4, respectively. The electrical conductivity of the sintered samples was measured by four probe DC method from 300 to 800 ℃. The cathode with LSC particle by citric acid- nitrate low temperature self-propagating combustion method has higher electrical conductivity. In order to investigate the stability, the two samples were put into the muffle furnace to heat up in air at 800℃for 800 h. To analysis the reason for reduced electrical conductivity, the crystal structure and the particle micrograph of the cathode wafers before and after an exposure were investigated with XRD and SEM. The result shows that new crystal structure appears in both the two kinds of cathode wafers and crystal micrographs change a lot.
基金supported by the National Natural Science Foundation of China (50806066)the National Basic Research Program of China (2009CB219802)the Program of Introducing Talents of Discipline to University (B08026)
文摘Lean premixed flame characteristics of several typical low calorific value (LCV) syngases (basis CO/H2/CH4/CO2/N2),including bituminous coal,wood residue,corn core,and wheat straw gasification syngas,were investigated using OH planar laser induced fluorescence (PLIF) technology.OH radical distributions within the turbulent flame were measured for different turbulence intensities.Flame structures of syngases were analyzed and characterized with respect to burnt and unburnt regions,flame curvature (sharp cusp),local extinction (holes and penetration),OH reaction layer thickness,wrinkling,and other features,with OH-PLIF instantaneous images and statistical analysis.Results show that H2 content,LCV,and turbulence intensity are the most effective factors influencing the OH radical intensity and thickness of OH radical layers.The bituminous coal gasification syngas with relatively higher LCV and H2 content tends to burn out easily.Through changes in thickness of the OH radical layers and signal intensities,the reaction layer can be compressed by intensifying turbulence and thereby the combustion processes of syngas.
基金supported by the Research Foundation of Science and Technology Department of Zhejiang Province,China (2009C21023)the China Postdoctoral Science Foundation (20080441248)
文摘In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocolloid viscosity.Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion.The fractal concept is introduced to describe the irregular and dynamic aggregate structure.The structure of aggregates,which is considered to play an important role in viscosity,is affected by both intermolecular and electrostatic forces.The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction.The aggregate structure is also affected by the pH of the solution.Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force,the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure.
基金supported by the Inner Mongolia Autonomous Region Open Major Basic Research Project(Grant No.20120905)the National Natural Science Foundation of China(Grant No.51666014)
文摘Wind tunnel experiments of the wake characteristics of a two-blade wind turbine, in the downstream region of 0
基金supported by the Foundation of Key Laboratory for Wind and Solar Power Energy Utilization Technology,Ministry of Education and Inner Mongolia Construction(Grant No.201503)the National Natural Science Foundation of China(Grant No.51346006)
文摘Large-eddy simulation(LES) with fully resolved rotor method(FRM) is applied to explore the turbulent wake flow characteristics and vortex evolution laws of a two-bladed horizontal-axis wind turbine. Relevant wind tunnel experiments have been done based on time resolved particle image velocimetry(TRPIV) technique. The simulation results are validated by the experimental data and they are in good agreement. The axial average velocity, turbulent kinetic energy, shear Reynolds stress, and vortex structure of the wind turbine wake are analyzed based on the comparison of LES results and experimental data. It is observed that the wake diameter of wind turbine enlarges with the increase of tip speed ratio(TSR). Turbulent kinetic energy meets its minimum value when x/R=2.0. Shear Reynolds stress appears a positive peak in the near wake when x/R<2.0, and the value of shear Reynolds stress decreases along the axial direction. The blade tip vortex dissipates more quickly than the central vortex in the wind turbine wake, and the gradient of the relationship curve between the blade tip vortex core position and the vortex age decreases as the TSR increases. With the increase of TSR, the thrust coefficient increases, and the power coefficient increases first and then decreases.The present work proves that LES with FRM could calculate wind turbine turbulent wake flow with a high accuracy.
文摘In order to eliminate secondary pollution caused by municipal solid waste(MSW)incineration,a MSW gasification and melting process is proposed.The process is expected to reduce the emission of pollutants,especially heavy-metals and dioxins.In this paper,the combustible components of MSW and simulated MSW were gasified in a lab-scale fluidized bed at 400°C-700°C when the excess air ratio(ER)was between 0.2 and 0.8.The experimental results indicated that the MSW could be gasified effectively in a fluidized bed at approximately 600°C-700°C when excess air ratio was 0.2-0.4.The melting characteristics of two typical fly ash samples from MSW incinerators were investigated.The results indicated that fly ash of pure MSW incineration could be melted at approximately 1,300°C and that of MSW and coal co-combustion could be melted at approximately 1,400°C.When temperature was over 1,100°C,more than 99.9%of the dioxins could be decomposed and most of the heavy-metals could be solidified in the slag.Based on the above experiments,two feasible MSW gasification and mel-ting processes were proposed for low calorific value MSW:(1)sieved MSW gasification and melting system,which was based on an idea of multi-recycle;(2)gasification and melting scheme of MSW adding coal as assistant fuel.
基金supported by the National Natural Science Foundation of China(Grant No.50476057)。
文摘The analysis of microstructure and polymeriza-tion degree showed that acid wash altered the cellulose morphology and decreased the polymerization degree signifi-cantly.A series of experiments were done to study the effect of acid wash on cellulose rapid pyrolysis.Experimental results showed that under acid pretreatment,the yield of bio-oil decreased while the production of gas and char increased.With an increase in acid concentration,this trend would be further enhanced.Sulphuric acid limited the formation of bio-oil more effectively than hydrochloric acid and pho-sphoric acid.According to the GC-MS analysis of bio-oil,high-concentration acid wash restrained the formation of levoglucosan by catalyzing dehydration process and cross linking reaction.
基金This work was supported by the National Natural Science Foundation of China(52036008).
文摘The leakage accident of molten salt in the thermal storage tank will cause the shutdown and enormous economic losses of Concentrated Solar Power plants.This study investigates the heat transfer and flow characteristic of commercial molten nitrates leaking in the thermal state porous foundation material.The migration width and depth of three molten nitrates,Solar Salt(60 wt%NaNO_(3)-40 wt%KNO_(3)),Hitec XL(7 wt%NaNO_(3)-45 wt%KNO_(3)-48 wt%Ca(NO_(3))_(2))and Hitec(7 wt%NaNO_(3)-53 wt%KNO_(3)-40 wt%NaNO_(2)),are obtained at different operating temperatures.Experimental results indicate that the temperature rising rate of foundation material in the nitrate leaking process has a trend of first increasing rapidly and then decreasing,and then it increases slightly as the depth increases.The temperature rising rate increases obviously with increasing operating temperature of the molten salt.With the increase of the operating temperature,the distances from the storage tank bottom to solid salt in foundation and the total migration depths both increase obviously,while the average migrating widths change slightly.At the same operating temperature,the temperature rising rate of the foundation material where Hitec XL and Hitec salt leak is significantly greater than that with Solar Salt,which is closely related to the melting points of molten salts.The migration depth of Hitec is 95.03%greater than that of Solar Salt and 19.11%larger than that of Hitec XL at the operating temperature of 300℃.Compared with Hitec XL,the leakage of Hitec with a smaller viscosity has a larger temperature rising rate and a wider and deeper transporting range during the leakage process.This work could guide the installation locations of the leak detection devices for high temperature storage tank and the environmental treatment of leaking accident.
基金supported by the Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 51621005)
文摘Pyrolysis was carried out in an entrained flow drop-tube furnace（DTF） and tube furnace（TF） using Pingzhuang lignite coal with various catalyst concentrations（2 wt%, 4 wt%, and 6 wt%） of KCl and CaCl2 for the syngas component at 800°C–1200°C. Five catalysts（KCl, CaCl2, NiCl2, MnCl2, and ZnCl2） at 6 wt% were chosen for DTF at 800°C–1200°C. An online gas chromatograph analyzer and the Fourier transform infrared spectra were used for the analysis of the syngas and char structure. Results showed that the overall CO2 and CH4 content in DTF was lower than that in TF, mainly due to the CH4 carbon reaction at high temperature. Moreover, the CO% in DTF was higher than in the TF experiment, as char reacts with carbon dioxide to form carbon monoxide. In DTF experiment, the maximum and minimum CO2 content was 15.20% with 6 wt% Mn at 800°C and 0.33% with 6 wt% K at 1100°C, respectively. The maximum CO% was found in raw coal. Concentrations of Mn2+, Zn2+, and K+can significantly increase H2%, whereas Ca2+ and Ni2+ have a minor effect on H2%; however, the overall presence of catalyst has a positive impact on the H2 content.
基金supported by the National Natural Science Foundation of China (51176169)the Program of Introducing Talents of Discipline to University (B08026)
文摘A novel method to apply artificial neural network (ANN) for both chemical kinetics reduction and source term evaluation is introduced and tested in direct numerical simulation (DNS) and large eddy simulation (LES) of reactive flows. To gather turbulence affected flame data for ANN training, a new computation-economical method, called 1D pseudo-velocity disturbed flame (PVDF), is developed and used to generate thermo-chemical states independent of the modeled flame. Then a back-propagation ANN is trained using scaled conjugate gradient algorithm to memorize the sample states with reduced orders. The new method is employed in DNS and LES modeling of H2 /air and C3H8 /air premixed flames experiencing various levels of turbulence. The test result shows that compared to traditional computation with full mechanism and direct integration, this method can obtain quite large speed-ups with adequate prediction accuracy.
基金supported by National Science Fund for Distinguished Young Scholars(51825605)。
文摘The main objective of this article was to experimentally investigate the dynamic response of diffusion flame under acoustic excitation in a laboratory-scale burner.Two parametric variations of the burner,the burner inlet length and variation of the airflow rate,were studied.Experimental results were analyzed through nonlinear time series analysis and several resonance characteristics were obtained.Results indicate that the flame-acoustic resonance only appears under certain frequencies together with the fuel tube vibration.Resonance characteristics of the combustion chamber and air inlet in the non-premixed burner indicate quasi-periodic or limit cycle oscillations,respectively.Flame-acoustic resonance would trigger the frequency and amplitude mode-transition in burners.Moreover,the intermittency of flame heat release was observed under variation of inlet length and airflow rate in the burner;the 445 mm case shows more frequency peaks and fluctuations than the 245 mm one.Four typical flame forms were examined during the flame-acoustic resonance conditions,evolves from wrinkled flames to diverged flames,then evolves to reattached flames and finally to blow-off flames.This study proposed the practical application of nonlinear time-series analysis method as a detection tool for flame-acoustic resonance in laboratory non-premixed burners,which could contribute to the detection and prevention of potential thermoacoustic instabilities or resonance structure failures of industrial boilers.Finally,this study demonstrates an alternative to conventional linear tool for the characterization of nonlinear acoustic resonance in industrial boilers.
基金the sponsorship by le Ministère de la Recherche de France the Programme Sino-Francais de Recherches Avancées (PRA E01-06: Combustion propre : aspects numériques et expérimentaux) the National Natural Science Foundation of China (Grant No.N50106015).
文摘Two-flux method can be used, as a simplification for the radiative heat transfer, to predict heat flux in a slab consisting of gas and particles. In the original two-flux method (Schuster, 1905 and Schwarzschild, 1906), the radiation field was assumed to be isotropic. But for gas-particles mixture in combustion environments, the scatterings of particles are usually anisotropic, and the original two-flux method gives critical errors when ignoring this anisotropy. In the present paper, a multilayer four-flux model developed by Rozé et al. (2001) is extended to calculate the radiation heat flux in a slab containing participating particles and gas mixture. The analytic resolution of the radiative transfer equation in the framework of a two-flux approach is presented. The average crossing parameter ε and the forward scattering ratio ζ are defined to describe the anisotropy of the radiative field. To validate the model, the radiation transfer in a slab has been computed. Comparisons with the exact analytical result of Modest (1993) and the original two-flux model show the exactness and the improvement. The emissivity of a slab containing flyash/CO2/H2O mixture is obtained using the new model. The result is identical with that of Goodwin (1989).
