Spinel zinc ferrites ZnFe2O4, prepared by co-precipitation method using the zinc nitrate Zn(NO3)2·6H2O and ferric nitrate Fe(NO3)3·2H2O as the raw materials, were characterized by the thermo gravimetric anal...Spinel zinc ferrites ZnFe2O4, prepared by co-precipitation method using the zinc nitrate Zn(NO3)2·6H2O and ferric nitrate Fe(NO3)3·2H2O as the raw materials, were characterized by the thermo gravimetric analysis (TG) and differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The influence of synthesis conditions, such as Zn/Fe molar ratio, pH value, the sintering temperature and time, on the microstructures was detailedly investigated. The relationships between the microstructures and the synthesis conditions were discussed. The results show that the pure spinel zinc ferrites ZnFe2O4 are formed when the Zn/Fe molar ratio is 1.05∶2 at pH=8.5 or Zn/Fe molar ratio is 1∶2 at Ph=9-10, and the precursors are sintered at 1100 ℃ for 4 h. Especially no other phases are observed when the Zn/Fe molar ratio is 1∶2 at pH=10 and the precursor is sintered above 700 ℃ for 4 h. The higher sintering temperature and longer sintering time contribute to grain growth.展开更多
Protein folding involves the aminoacid sequence to come forth and form an energy minimized structure.Recently molecular crowding leading to increase in viscosity is said to be one of the major concerns affecting prote...Protein folding involves the aminoacid sequence to come forth and form an energy minimized structure.Recently molecular crowding leading to increase in viscosity is said to be one of the major concerns affecting protein folding.Many external fluorescent probes are used to detect such increases in viscosity.Since most of the protein sequences contain L-Phe and L-Trp,in this study we have used these aminoacids as probes to detect changes in viscosity.This study will help to advance the knowledge on molecular crowding effects in protein folding.展开更多
A new type of hydraulic turbine and its design theory is presented.This turbine has the advantages of the most widely used Francis turbine and Straflo tubine,has its own specific theoretical basis,compact structure, s...A new type of hydraulic turbine and its design theory is presented.This turbine has the advantages of the most widely used Francis turbine and Straflo tubine,has its own specific theoretical basis,compact structure, small volume, low cost and steady operation. And it is convenient to be transported , installed and maintained, and has good hydraulic and cavitation performance. It is named Straflo-Francis turbine.展开更多
Ultrasound is used in various chemical reaction processes, and these reactions are influenced by ultrasonic frequency. A threshold power is required for the ultrasonic degradation reaction and oxidation reaction cause...Ultrasound is used in various chemical reaction processes, and these reactions are influenced by ultrasonic frequency. A threshold power is required for the ultrasonic degradation reaction and oxidation reaction caused by hydroxyl radicals, and the cavitation threshold power is also influenced by frequency generally. In this study, the effects of frequency on the threshold power of methylene blue degradation and KI oxidation were investigated in the range between 22.8 kHz and 1640 kHz. The threshold power of KI oxidation reaction increased with increasing frequency. This phenomenon well agrees with previous study, and it is revealed that the generation of I-3?ion is caused by oxidation reaction of Iˉ ions with hydroxyl radicals. On the other hand, the threshold power of methylene blue degradation reaction was not affected by frequency. The ultrasonic degradation of methylene blue is considered to be caused by hydroxyl radicals, and there is a linear relationship between degradation rate constant and sonochemical efficiency value. However, it is guessed that the degradation of methylene blue is occurred inside cavitation bubble by pyrolysis at high frequency regions.展开更多
In accordance with the cerium-lanthanum ratio of fluorocerium ores in the mineralogy of the Baiyun Ebo process, the (Ce,La)CO<sub>3</sub>F grains were synthesised by hydrothermal method using pure material...In accordance with the cerium-lanthanum ratio of fluorocerium ores in the mineralogy of the Baiyun Ebo process, the (Ce,La)CO<sub>3</sub>F grains were synthesised by hydrothermal method using pure material to simulate bastnaesite minerals, and used as NH<sub>3</sub>-SCR denitrification catalysts. The activity results showed that the synthetic (Ce,La)CO<sub>3</sub>F was roasted at 500<span><span><span style="font-family:;" "=""><span style="white-space:nowrap;">˚</span>C</span></span></span><span><span><span style="font-family:;" "="">, and the NOx conversion was 27% at 200</span></span></span><span><span><span style="font-family:;" "=""><span style="white-space:nowrap;">˚</span>C</span></span></span><span><span><span style="font-family:;" "="">. The NH<sub>3</sub></span></span></span><span><span><span style="font-family:;" "="">-</span></span></span><span><span><span style="font-family:;" "="">SCR catalytic activity of the synthesised (Ce,La)CO<sub>3</sub>F was improved by loaded transition metal Mn. The best catalyst was found to be produced by impregnating (Ce,La)CO<sub>3</sub>F with 1 mol/L manganese nitrate solution, with a NOx conversion of 80% at 250</span></span></span><span><span><span style="font-family:;" "=""><span style="white-space:nowrap;">˚</span>C</span></span></span><span><span><span style="font-family:;" "="">. The loading of Mn resulted in the appearance of numerous well-dispersed MnOx species on the catalyst surface, the dispersion of Ce<sub>7</sub>O<sub>12</sub> species was also greatly enhanced, and the reduction in grain size indicated that Mn<sup>n+</sup> entered into the (Ce,La)CO<sub>3</sub>F lattice causing lattice shrinkage. The number of acidic sites on the catalyst surface and the redox capacity were enhanced. The amount of Ce<sup>3+</sup> in the catalyst was also enhanced by the introduction of Mn<sup>n+</sup>, but the proportion of adsorbed oxygen decreased, which indicated that the introduction of Mn<sup>n+</sup> was detrimental to the increase in the proportion of adsorbed oxygen. The reaction mechanisms of the (Ce,La)CO<sub>3</sub>F and Mn/(Ce,La)CO<sub>3</sub>F catalysts were investigated by <i>in-situ</i> Fourier transform infrared spectroscopy (FTIR). The results showed that catalysts followed the E-R and L-H mechanisms. When loaded with Mn, the main reactive species in the L-H mechanism were the </span></span></span><span><span><span style="font-family:;" "=""><span></span></span></span></span><span><span><span style="font-family:;" "=""><span> </span>(ad) species on the Br<span style="white-space:nowrap;">ø</span>nsted acidic site and the O-Ce<sup>3+</sup>-O-NO, O-Mn<sup>3+</sup>-O-NO species. The main reactive species for the E-R mechanism were NH<sub>3</sub>/</span></span></span><span><span><span style="font-family:;" "=""><span></span></span></span></span><span><span><span style="font-family:;" "=""><span> </span>(ad) species and NO. The </span></span></span><span><span><span style="font-family:;" "=""><span></span></span></span></span><span><span><span style="font-family:;" "=""><span> </span>(ad) species on the Br<span style="white-space:nowrap;">ø</span>nsted acidic sites act as the main reactive NH3</span></span></span><span><span><sub><span style="font-family:;" "=""> </span></sub></span></span><span><span><span style="font-family:;" "="">(g) adsorbing species, bonded to the Ce<sup>4+</sup> in the carrier (Ce,La)CO<sub>3</sub>F to participate in the acid cycle reaction. The introduction of Mn<sup>n+</sup> increases the number of Br<span style="white-space:nowrap;">ø</span>nsted acidic sites on the catalyst surface, and acts as an adsorption site for NO, to react with NO to generate more monodentate nitrate species, to participate in the redox cycle reactions. The above results indicated that Mn<sup>n+</sup> and (Ce,La)CO<sub>3</sub>F have a good mutual promotion effect, which makes the loaded catalyst have excellent performance, which provides a theoretical basis for the high value utilization of bastnaesite</span></span></span><span><span><span style="font-family:;" "="">.</span></span></span>展开更多
The seas of northern Europe are strongly affected by human activities and there is a great need for improved marine conservation. The same region is also the current hotspot for offshore wind power development. Wind f...The seas of northern Europe are strongly affected by human activities and there is a great need for improved marine conservation. The same region is also the current hotspot for offshore wind power development. Wind farms can have negative environmental impacts during construction, but during the operational phase many organisms are attracted to the foundations and thereby may also find refuge from fisheries. Given the recent implementation of marine spatial planning in Europe and elsewhere, this is a critical time to address potential compatibility and synergies between marine conservation and wind power. This review concludes that offshore wind farms can be at least as effective as existing marine protected areas in terms of creating refuges for benthic habitats, benthos, fish and marine mammals. The degree of advantage for these organisms depends on the location of the wind farm and the level of imposed fishing restriction. Under certain conditions wind farms may even be more efficient means of conservation than ordinary marine protected areas. However, offshore wind farms can be negative for several species of seabirds, essentially as occupying preferred feeding or wintering grounds. In areas important to these seabirds wind farms may not comply with conservation. The results bring important messages to marine spatial planning as some but not all wind farms can be spatially combined with, and even synergistic to, marine conservation.展开更多
A three-dimensional, nineteen-velocity(D3Q19) Lattice Boltzmann Method(LBM) model was developed to simulate the fluid flow of a laminar square jet in cross flows based on the single relaxation time algorithm. The code...A three-dimensional, nineteen-velocity(D3Q19) Lattice Boltzmann Method(LBM) model was developed to simulate the fluid flow of a laminar square jet in cross flows based on the single relaxation time algorithm. The code was validated by the mathematic solution of the Poiseuille flow in a square channel, and was further validated with a previous well studied empirical correlation for the central trajectory of a jet in cross flows. The developed LBM model was found to be able to capture the dominant vortex, i.e. the Counter-rotating Vortex Pair(CVP) and the upright wake vortex. Results show that the incoming fluid in the cross flow channel was entrained into the leeside of the jet fluid, which contributes to the blending of the jet. That the spread width of the transverse jet decreases with the velocity ratio. A layer-organized entrainment pattern was found indicating that the incoming fluid at the lower position is firstly entrained into the leeside of the jet, and followed by the incoming fluid at the upper position.展开更多
In this paper, FLUENT software was used to simulate the burning process in a utility boiler. Chose the kinetics/diffusion-limited as combustion model, two-competing-rates as devolatilization model, RNG k-εmodel as vi...In this paper, FLUENT software was used to simulate the burning process in a utility boiler. Chose the kinetics/diffusion-limited as combustion model, two-competing-rates as devolatilization model, RNG k-εmodel as viscous model, and PDF model as combustion turbulent flow model. Numerical calculation of NOx formation in a 330 MW cyclone-opposed coal-fired utility boiler with 32 double air registers was done. The distribution characteristics of temperature, NOx and oxygen concentration in furnace were studied. They were symmetrically distributed in furnace. In the combustion area, temperature and NOx concentration are high, while oxygen concentration is low. Temperature and NOx concentration are declined gradually along with furnace height, while oxygen concentration is raised. The higher the temperature is and the greater the excess air coefficient is, the more NOx formation.展开更多
The ultrasonic degradation of methylene blue at a frequency of 490 kHz was carried out in the absence and presence of TiO2 or Al2O3 particle, and the effects of amounts of particle on the enhancement of degradation ra...The ultrasonic degradation of methylene blue at a frequency of 490 kHz was carried out in the absence and presence of TiO2 or Al2O3 particle, and the effects of amounts of particle on the enhancement of degradation rate constant estimated by assuming first-order-kinetics were investigated. The degradation reaction was enhanced by particle addition, and the apparent degradation rate constant is proportional to the increase in amount of particle. In addition, the constant of proportionality is not influenced by degraded material and ultrasonic frequency. However, particle type influences the constant of proportionality, and the value of TiO2 particle is about 6 times as large as that of Al2O3 particle.展开更多
In the last three decades much effort has been devoted in process integration as a way to improve economic and environmental performance of chemical processes. Although the established frameworks have undergone consta...In the last three decades much effort has been devoted in process integration as a way to improve economic and environmental performance of chemical processes. Although the established frameworks have undergone constant refinement toward formulating and solving complicated process integration problems, less attention has been drawn to the problem of sequential applications of mass integration. This work addresses this problem by proposing an algorithm for optimal ordering of the process sinks in direct recycling problems, which is compatible with the typical mass integration formulation. The order consists in selecting the optimal sink at a specific integration step given the selection of the previous steps and the remaining process sources. Such order is identified through a succession of preemptive goal programming problems, namely of optimization problems characterized by more objectives at different priority levels. Indeed, the target for each sink is obtained by maximizing the total flow recycled from the available process sources to this sink and then minimizing the use of pure sources, starting from the purest one;the hierarchy is respected through a succession of linear optimization problems with a single objective function. While the conditional optimality of the algorithm holds always, a thorough statistical analysis including structured to random scenarios of process sources and process sinks shows how frequently the sequential ordering algorithm is outperformed with respect to the total recycled amount by a different selection of process sinks with the same cardinality. Two more case studies proving the usefulness of ordering the process sinks are illustrated. Extensions of the algorithm are also identified to cover more aspects of the process integration framework.展开更多
In the face of the pressing environmental issues,the past decade witnessed the booming development of the distributed energy systems(DESs).A notable problem of DESs is the inevitable uncertainty that may make DESs dev...In the face of the pressing environmental issues,the past decade witnessed the booming development of the distributed energy systems(DESs).A notable problem of DESs is the inevitable uncertainty that may make DESs deviate significantly from the deterministically obtained expectations,in both aspects of optimal design and economic operation.It thus necessitates the sensitivity analysis to quantify the impacts of the massive parametric uncertainties.This paper aims to give a comprehensive quantification,and carries out a multi-stage sensitivity analysis on DESs from the perspectives of evaluation criteria,optimal design and economic operation.First,a mathematical model of a DES is developed to present the solutions to the three stages of the DES.Second,the Monte-Carlo simulation is carried out subject to the probabilistic distributions of the energy,technical and economic parameters.Based on the simulation results,the variance-based Sobol method is applied to calculate the individual importance,interactional importance and total importance of various parameters.The comparison of the multi-stage results shows that only a few parameters play critical roles while the uncertainty of most of the massive parameters has little impact on the system performance.In addition,the influence of parameter interactions in the optimal design stage are much stronger than that in the evaluation criteria and operation strategy stages.展开更多
Experiments were carried out to study the heat transfer performance of an impinging jet in a cross flow.Several parameters including the jet-to-cross-flow mass ratio(X=2%-8%), the Reynolds number(Red=1434-5735)and the...Experiments were carried out to study the heat transfer performance of an impinging jet in a cross flow.Several parameters including the jet-to-cross-flow mass ratio(X=2%-8%), the Reynolds number(Red=1434-5735)and the jet diameter(d=2-4 mm) were explored. The heat transfer enhancement factor was found to increase with the jet-to-cross-flow mass ratio and the Reynolds number, but decrease with the jet diameter when other parameters maintain fixed. The presence of a cross flow was observed to degrade the heat transfer performance in respect to the effect of impinging jet to the target surface only. In addition, an impinging jet was confirmed to be capable of enhancing the heat transfer process in considerable amplitude even though the jet was not designed to impinge on the target surface.展开更多
Aqueous 1,8-diamino-p-menthane (KIER-C3) and commercially available amine solutions were tested for CO2 absorption. A 2-amino-2-methyl-1-propanol (AMP) solution with an addition of KIER-C3 showed 9.3% and 31.6% higher...Aqueous 1,8-diamino-p-menthane (KIER-C3) and commercially available amine solutions were tested for CO2 absorption. A 2-amino-2-methyl-1-propanol (AMP) solution with an addition of KIER-C3 showed 9.3% and 31.6% higher absorption rate for CO2 than the AMP solution with an addition of monoethanolamine (MEA) and ammonia (NH3), respectively. The reaction rate constant for CO2 absorption by the AMP/KIER-C3 solution was determined by the following equation: k2,AMP/C3 = 7.702×106 exp (-2248.03/T). A CO2 loading ratio of the AMP/KIER-C3 solution was also 2 and 3.4-times higher than that of the AMP/NH3 solution and the AMP/MEA solution, respectively. Based on the experimental results, KIER-C3 may be used as an excellent additive to increase CO2 absorption capability of AMP.展开更多
To make coal-fired power generation more environmentally friendly,China has initiated a series of ultra-low emission ret-rofits to the air pollution control(APC)system of the existing power plants.In this study,a life...To make coal-fired power generation more environmentally friendly,China has initiated a series of ultra-low emission ret-rofits to the air pollution control(APC)system of the existing power plants.In this study,a life cycle assessment(LCA)is conducted to analyze the environmental net benefits for the typical ultra-low emission retrofit of a 1000 MW power plant.The key processes,substances,and APC devices are verified and discussed.The results confirm that the retrofit effectively decreases the environmental stress of acidification potential(AP),eutrophication potential(EP),and photochemical ozone creation potential(POCP)by 69%-79%,which can be attributed to significantly reduced emissions at the stack.However,the retrofit has also increased other impact categories by 24%-79%,primarily due to the consumption of additional elec-tricity and adsorbents.The retrofit of selective catalytic reduction,electrostatic precipitator(ESP),and wet limestone flue gas desulfurization devices has a dominant effect on the impacts of EP,human toxicity potential(HTP),and AP.A newly installed wet ESP shows some environmental benefits(only for AP),but causes considerable burdens,in particular for the investigated impact categories global warming potential(GWP),marine aquatic ecotoxicity(MAETP),and abiotic depletion fossil(ADP fossil).The obtained results indicate that the hidden environmental consequences,which are associated with the production of energy and materials,need to be examined more comprehensively to inform the development of ultra-low emission technologies and strategies effectively.展开更多
基金Funded by the National Science Foundation in China (No. 10804117)Natural Science Foundation of Shanghai (No. 08ZR1421900)the Major Program for the Fundamental Research of Shanghai (No. 06JC14033)
文摘Spinel zinc ferrites ZnFe2O4, prepared by co-precipitation method using the zinc nitrate Zn(NO3)2·6H2O and ferric nitrate Fe(NO3)3·2H2O as the raw materials, were characterized by the thermo gravimetric analysis (TG) and differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The influence of synthesis conditions, such as Zn/Fe molar ratio, pH value, the sintering temperature and time, on the microstructures was detailedly investigated. The relationships between the microstructures and the synthesis conditions were discussed. The results show that the pure spinel zinc ferrites ZnFe2O4 are formed when the Zn/Fe molar ratio is 1.05∶2 at pH=8.5 or Zn/Fe molar ratio is 1∶2 at Ph=9-10, and the precursors are sintered at 1100 ℃ for 4 h. Especially no other phases are observed when the Zn/Fe molar ratio is 1∶2 at pH=10 and the precursor is sintered above 700 ℃ for 4 h. The higher sintering temperature and longer sintering time contribute to grain growth.
文摘Protein folding involves the aminoacid sequence to come forth and form an energy minimized structure.Recently molecular crowding leading to increase in viscosity is said to be one of the major concerns affecting protein folding.Many external fluorescent probes are used to detect such increases in viscosity.Since most of the protein sequences contain L-Phe and L-Trp,in this study we have used these aminoacids as probes to detect changes in viscosity.This study will help to advance the knowledge on molecular crowding effects in protein folding.
基金This project is supported by China Ministry of Water Conservancy and the Key Subject of Flowing Machinery in Sichuan.
文摘A new type of hydraulic turbine and its design theory is presented.This turbine has the advantages of the most widely used Francis turbine and Straflo tubine,has its own specific theoretical basis,compact structure, small volume, low cost and steady operation. And it is convenient to be transported , installed and maintained, and has good hydraulic and cavitation performance. It is named Straflo-Francis turbine.
文摘Ultrasound is used in various chemical reaction processes, and these reactions are influenced by ultrasonic frequency. A threshold power is required for the ultrasonic degradation reaction and oxidation reaction caused by hydroxyl radicals, and the cavitation threshold power is also influenced by frequency generally. In this study, the effects of frequency on the threshold power of methylene blue degradation and KI oxidation were investigated in the range between 22.8 kHz and 1640 kHz. The threshold power of KI oxidation reaction increased with increasing frequency. This phenomenon well agrees with previous study, and it is revealed that the generation of I-3?ion is caused by oxidation reaction of Iˉ ions with hydroxyl radicals. On the other hand, the threshold power of methylene blue degradation reaction was not affected by frequency. The ultrasonic degradation of methylene blue is considered to be caused by hydroxyl radicals, and there is a linear relationship between degradation rate constant and sonochemical efficiency value. However, it is guessed that the degradation of methylene blue is occurred inside cavitation bubble by pyrolysis at high frequency regions.
文摘In accordance with the cerium-lanthanum ratio of fluorocerium ores in the mineralogy of the Baiyun Ebo process, the (Ce,La)CO<sub>3</sub>F grains were synthesised by hydrothermal method using pure material to simulate bastnaesite minerals, and used as NH<sub>3</sub>-SCR denitrification catalysts. The activity results showed that the synthetic (Ce,La)CO<sub>3</sub>F was roasted at 500<span><span><span style="font-family:;" "=""><span style="white-space:nowrap;">˚</span>C</span></span></span><span><span><span style="font-family:;" "="">, and the NOx conversion was 27% at 200</span></span></span><span><span><span style="font-family:;" "=""><span style="white-space:nowrap;">˚</span>C</span></span></span><span><span><span style="font-family:;" "="">. The NH<sub>3</sub></span></span></span><span><span><span style="font-family:;" "="">-</span></span></span><span><span><span style="font-family:;" "="">SCR catalytic activity of the synthesised (Ce,La)CO<sub>3</sub>F was improved by loaded transition metal Mn. The best catalyst was found to be produced by impregnating (Ce,La)CO<sub>3</sub>F with 1 mol/L manganese nitrate solution, with a NOx conversion of 80% at 250</span></span></span><span><span><span style="font-family:;" "=""><span style="white-space:nowrap;">˚</span>C</span></span></span><span><span><span style="font-family:;" "="">. The loading of Mn resulted in the appearance of numerous well-dispersed MnOx species on the catalyst surface, the dispersion of Ce<sub>7</sub>O<sub>12</sub> species was also greatly enhanced, and the reduction in grain size indicated that Mn<sup>n+</sup> entered into the (Ce,La)CO<sub>3</sub>F lattice causing lattice shrinkage. The number of acidic sites on the catalyst surface and the redox capacity were enhanced. The amount of Ce<sup>3+</sup> in the catalyst was also enhanced by the introduction of Mn<sup>n+</sup>, but the proportion of adsorbed oxygen decreased, which indicated that the introduction of Mn<sup>n+</sup> was detrimental to the increase in the proportion of adsorbed oxygen. The reaction mechanisms of the (Ce,La)CO<sub>3</sub>F and Mn/(Ce,La)CO<sub>3</sub>F catalysts were investigated by <i>in-situ</i> Fourier transform infrared spectroscopy (FTIR). The results showed that catalysts followed the E-R and L-H mechanisms. When loaded with Mn, the main reactive species in the L-H mechanism were the </span></span></span><span><span><span style="font-family:;" "=""><span></span></span></span></span><span><span><span style="font-family:;" "=""><span> </span>(ad) species on the Br<span style="white-space:nowrap;">ø</span>nsted acidic site and the O-Ce<sup>3+</sup>-O-NO, O-Mn<sup>3+</sup>-O-NO species. The main reactive species for the E-R mechanism were NH<sub>3</sub>/</span></span></span><span><span><span style="font-family:;" "=""><span></span></span></span></span><span><span><span style="font-family:;" "=""><span> </span>(ad) species and NO. The </span></span></span><span><span><span style="font-family:;" "=""><span></span></span></span></span><span><span><span style="font-family:;" "=""><span> </span>(ad) species on the Br<span style="white-space:nowrap;">ø</span>nsted acidic sites act as the main reactive NH3</span></span></span><span><span><sub><span style="font-family:;" "=""> </span></sub></span></span><span><span><span style="font-family:;" "="">(g) adsorbing species, bonded to the Ce<sup>4+</sup> in the carrier (Ce,La)CO<sub>3</sub>F to participate in the acid cycle reaction. The introduction of Mn<sup>n+</sup> increases the number of Br<span style="white-space:nowrap;">ø</span>nsted acidic sites on the catalyst surface, and acts as an adsorption site for NO, to react with NO to generate more monodentate nitrate species, to participate in the redox cycle reactions. The above results indicated that Mn<sup>n+</sup> and (Ce,La)CO<sub>3</sub>F have a good mutual promotion effect, which makes the loaded catalyst have excellent performance, which provides a theoretical basis for the high value utilization of bastnaesite</span></span></span><span><span><span style="font-family:;" "="">.</span></span></span>
文摘The seas of northern Europe are strongly affected by human activities and there is a great need for improved marine conservation. The same region is also the current hotspot for offshore wind power development. Wind farms can have negative environmental impacts during construction, but during the operational phase many organisms are attracted to the foundations and thereby may also find refuge from fisheries. Given the recent implementation of marine spatial planning in Europe and elsewhere, this is a critical time to address potential compatibility and synergies between marine conservation and wind power. This review concludes that offshore wind farms can be at least as effective as existing marine protected areas in terms of creating refuges for benthic habitats, benthos, fish and marine mammals. The degree of advantage for these organisms depends on the location of the wind farm and the level of imposed fishing restriction. Under certain conditions wind farms may even be more efficient means of conservation than ordinary marine protected areas. However, offshore wind farms can be negative for several species of seabirds, essentially as occupying preferred feeding or wintering grounds. In areas important to these seabirds wind farms may not comply with conservation. The results bring important messages to marine spatial planning as some but not all wind farms can be spatially combined with, and even synergistic to, marine conservation.
基金Supported by the National Natural Science Foundation of China(51476145,51476146)
文摘A three-dimensional, nineteen-velocity(D3Q19) Lattice Boltzmann Method(LBM) model was developed to simulate the fluid flow of a laminar square jet in cross flows based on the single relaxation time algorithm. The code was validated by the mathematic solution of the Poiseuille flow in a square channel, and was further validated with a previous well studied empirical correlation for the central trajectory of a jet in cross flows. The developed LBM model was found to be able to capture the dominant vortex, i.e. the Counter-rotating Vortex Pair(CVP) and the upright wake vortex. Results show that the incoming fluid in the cross flow channel was entrained into the leeside of the jet fluid, which contributes to the blending of the jet. That the spread width of the transverse jet decreases with the velocity ratio. A layer-organized entrainment pattern was found indicating that the incoming fluid at the lower position is firstly entrained into the leeside of the jet, and followed by the incoming fluid at the upper position.
基金Supported by Major Project of Tackle Key Problems of Shanghai (Z2003-1)
文摘In this paper, FLUENT software was used to simulate the burning process in a utility boiler. Chose the kinetics/diffusion-limited as combustion model, two-competing-rates as devolatilization model, RNG k-εmodel as viscous model, and PDF model as combustion turbulent flow model. Numerical calculation of NOx formation in a 330 MW cyclone-opposed coal-fired utility boiler with 32 double air registers was done. The distribution characteristics of temperature, NOx and oxygen concentration in furnace were studied. They were symmetrically distributed in furnace. In the combustion area, temperature and NOx concentration are high, while oxygen concentration is low. Temperature and NOx concentration are declined gradually along with furnace height, while oxygen concentration is raised. The higher the temperature is and the greater the excess air coefficient is, the more NOx formation.
文摘The ultrasonic degradation of methylene blue at a frequency of 490 kHz was carried out in the absence and presence of TiO2 or Al2O3 particle, and the effects of amounts of particle on the enhancement of degradation rate constant estimated by assuming first-order-kinetics were investigated. The degradation reaction was enhanced by particle addition, and the apparent degradation rate constant is proportional to the increase in amount of particle. In addition, the constant of proportionality is not influenced by degraded material and ultrasonic frequency. However, particle type influences the constant of proportionality, and the value of TiO2 particle is about 6 times as large as that of Al2O3 particle.
文摘In the last three decades much effort has been devoted in process integration as a way to improve economic and environmental performance of chemical processes. Although the established frameworks have undergone constant refinement toward formulating and solving complicated process integration problems, less attention has been drawn to the problem of sequential applications of mass integration. This work addresses this problem by proposing an algorithm for optimal ordering of the process sinks in direct recycling problems, which is compatible with the typical mass integration formulation. The order consists in selecting the optimal sink at a specific integration step given the selection of the previous steps and the remaining process sources. Such order is identified through a succession of preemptive goal programming problems, namely of optimization problems characterized by more objectives at different priority levels. Indeed, the target for each sink is obtained by maximizing the total flow recycled from the available process sources to this sink and then minimizing the use of pure sources, starting from the purest one;the hierarchy is respected through a succession of linear optimization problems with a single objective function. While the conditional optimality of the algorithm holds always, a thorough statistical analysis including structured to random scenarios of process sources and process sinks shows how frequently the sequential ordering algorithm is outperformed with respect to the total recycled amount by a different selection of process sinks with the same cardinality. Two more case studies proving the usefulness of ordering the process sinks are illustrated. Extensions of the algorithm are also identified to cover more aspects of the process integration framework.
基金supported by the Key Program of the Natural Science Foundation of Zhejiang Province(LZ21E060001)the Key Research and Development Plan of Zhejiang Province(2020C03115)。
基金supported by National Natural Science Foundation of China(No.51936003)National Key Research and Development Program of China(No.2018YFB1502904)
文摘In the face of the pressing environmental issues,the past decade witnessed the booming development of the distributed energy systems(DESs).A notable problem of DESs is the inevitable uncertainty that may make DESs deviate significantly from the deterministically obtained expectations,in both aspects of optimal design and economic operation.It thus necessitates the sensitivity analysis to quantify the impacts of the massive parametric uncertainties.This paper aims to give a comprehensive quantification,and carries out a multi-stage sensitivity analysis on DESs from the perspectives of evaluation criteria,optimal design and economic operation.First,a mathematical model of a DES is developed to present the solutions to the three stages of the DES.Second,the Monte-Carlo simulation is carried out subject to the probabilistic distributions of the energy,technical and economic parameters.Based on the simulation results,the variance-based Sobol method is applied to calculate the individual importance,interactional importance and total importance of various parameters.The comparison of the multi-stage results shows that only a few parameters play critical roles while the uncertainty of most of the massive parameters has little impact on the system performance.In addition,the influence of parameter interactions in the optimal design stage are much stronger than that in the evaluation criteria and operation strategy stages.
基金Supported by the National Natural Science Foundation of China(51106140)the Natural Science Foundation of Zhejiang Province(Z1110695)
文摘Experiments were carried out to study the heat transfer performance of an impinging jet in a cross flow.Several parameters including the jet-to-cross-flow mass ratio(X=2%-8%), the Reynolds number(Red=1434-5735)and the jet diameter(d=2-4 mm) were explored. The heat transfer enhancement factor was found to increase with the jet-to-cross-flow mass ratio and the Reynolds number, but decrease with the jet diameter when other parameters maintain fixed. The presence of a cross flow was observed to degrade the heat transfer performance in respect to the effect of impinging jet to the target surface only. In addition, an impinging jet was confirmed to be capable of enhancing the heat transfer process in considerable amplitude even though the jet was not designed to impinge on the target surface.
基金financially supported by the Brain Korea 21 Project in 2012the Energy Efficiency & Resources of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No.2006CCD11P011A -21-3-010)
文摘Aqueous 1,8-diamino-p-menthane (KIER-C3) and commercially available amine solutions were tested for CO2 absorption. A 2-amino-2-methyl-1-propanol (AMP) solution with an addition of KIER-C3 showed 9.3% and 31.6% higher absorption rate for CO2 than the AMP solution with an addition of monoethanolamine (MEA) and ammonia (NH3), respectively. The reaction rate constant for CO2 absorption by the AMP/KIER-C3 solution was determined by the following equation: k2,AMP/C3 = 7.702×106 exp (-2248.03/T). A CO2 loading ratio of the AMP/KIER-C3 solution was also 2 and 3.4-times higher than that of the AMP/NH3 solution and the AMP/MEA solution, respectively. Based on the experimental results, KIER-C3 may be used as an excellent additive to increase CO2 absorption capability of AMP.
基金This project is supported by the Chinese National Key R&D Program(No.2018YFB0605205)the Zhejiang Provincial Natural Science Foundation(Grant No.LQ21E060001).
文摘To make coal-fired power generation more environmentally friendly,China has initiated a series of ultra-low emission ret-rofits to the air pollution control(APC)system of the existing power plants.In this study,a life cycle assessment(LCA)is conducted to analyze the environmental net benefits for the typical ultra-low emission retrofit of a 1000 MW power plant.The key processes,substances,and APC devices are verified and discussed.The results confirm that the retrofit effectively decreases the environmental stress of acidification potential(AP),eutrophication potential(EP),and photochemical ozone creation potential(POCP)by 69%-79%,which can be attributed to significantly reduced emissions at the stack.However,the retrofit has also increased other impact categories by 24%-79%,primarily due to the consumption of additional elec-tricity and adsorbents.The retrofit of selective catalytic reduction,electrostatic precipitator(ESP),and wet limestone flue gas desulfurization devices has a dominant effect on the impacts of EP,human toxicity potential(HTP),and AP.A newly installed wet ESP shows some environmental benefits(only for AP),but causes considerable burdens,in particular for the investigated impact categories global warming potential(GWP),marine aquatic ecotoxicity(MAETP),and abiotic depletion fossil(ADP fossil).The obtained results indicate that the hidden environmental consequences,which are associated with the production of energy and materials,need to be examined more comprehensively to inform the development of ultra-low emission technologies and strategies effectively.