Simulation of oxygen transfer in liquid lead under influence of nanoparticles by using lattice Boltzmann method

Oxygen transfer presents a serious challenge in the application of liquid lead as a nuclear coolant in advanced reactors. To mitigate corrosion by liquid lead in contact with steel, carefully controlling the oxygen concentration has been used as an effective way. Oxygen needs to mix in liquid lead uniformly and quickly. To enhance oxygen transport in liquid lead, nanoparticles are added to the liquid metal. In the current study, a lattice Boltzmann method is applied to investigate natural convection of copper/lead and aluminum oxide/lead in two-dimensional simplified container. Two thermal boundary cases are evaluated in order to check the effect of different natural convection flow patterns on oxygen transport. Some useful information are obtained such as improvement in natural convection and reduction in oxygen equilibrium time.

Hydrodynamics and oxygen transfer in a novel extra-loop fluidized bed bioreactor

In this paper, the characteristics of fluid mixing time in a novel extra-loop fluidized bed were studied. The results showed that the mixing time was shortened with the increase of fluid velocity. All the discrete numbers of the reactor were above 0.2. The serial number n was 2.5 -3.0. It was judged accordingly that the reactor fluid state was continous stirred tank reactor （CSTR） mainly. When the inspiratory capacity increased the mixing time of the reactor was shortened. Thus the air input was beneficial for the fluid mixing. During the three phases mixing process, the mixing time of the reactor could be decreased by the n increase of carrier and air loading together, but the change was not significant. The parameters affecting the reactor fluid state were fluid velocity, inspiratory capacity and carrier. KLa could be increased with the air loading increase, and at the same gas/liquid ratio when the pressure drop was high, KL~ value was increased. The amount of carrier complex influence on KLa. As the carrier loading continued to increase, its value had been dropped but the changes was not significant, and optimization condition was found at above 800 1 000 g carrier loading （pouzzolane） or 600 g PVC. Under gas/liquid ratio of 0.8% -5.2%, KLa was （0.62-1.37）×10^-2· s^-1.

Oxygen Transfer and Hydrodynamics in a Flexible Fibre Biofilm Reactor for Wastewater Treatment

A flexible fibre biofilm reactor was developed for treatment of organic wastewaters.The hydrodynamic characteristics and mass transfer coefficients of oxygen were studied and compared with those of the conventional activated sludge processes.Tracer experiments were performed to obtain the residence time distributions of the reactors.The results indicated that both reactors could be treated as mixed flow reactors.The effects of flow rates of water and air on the overall mass transfer coefficient of oxygen were investigated,and the correlations between the mass transfer coefficient and the ratio of flow rates were obtained.Compared to the conventional activated sludge reactor,the mass transfer coefficients in the flexible fibre reactor were similar to but slightly lower,and less sensitive to the variation in the ratio of flow rates.It indicated that the fibre packing in the reactor hindered the oxygen transfer to some extent.

Catalytic C-H activation-initiated transdiannulation:An oxygen transfer route to ring-fluorinated tricyclic γ-lactones

Catalytic C–H activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic chemistry.Herein,we describe a new Rh(Ⅲ)-catalyzed C–H activation-initiated transdiannulation reaction of N,Ndimethyl enaminones with gem-difluorocyclopropenes in the presence of H_(2)O,enabling a facile and oxygen transfer access to ring-fluorinated tricyclicγ-lactones with a 6-5 ring-junction tetrasubstituted stereocenter.This approach features bond-forming/annulation efficiency,good functional group tolerance and complete regioselectivity,which may include a complex process consisting of Rh(Ⅲ)-catalyzed C(sp2)–H activation,cyclic alkene insertion,defluorinated ring-opening of gem-difluorocyclopropane,intramolecular oxygen transfer,intramolecular cyclization and oxidative hydration.

Oxygen transfer phenomenon between slag and molten steel for production of IF steel

FeO-containing slag originated from the basic oxygen furnace to the ladle is a major reoxidation source during the following secondary refining.Ladle slag reduction treatment(slag treatment)is one of the common countermeasures adopted to eliminate the steel contamination by FeO reoxidation.The oxygen transfer phenomenon between molten steel and slag was studied during the industrial production of interstitial-free(IF)steel,the measured and calculated oxygen activities in steel were compared,and the Fe–O equilibrium at the slag–molten steel interface was investigated by thermodynamic analysis.With slag treatment,the oxygen potential is higher in the molten steel than in the pre-deoxidation slag;this causes oxygen transfer from the molten steel to the slag,decreasing the efficiency of slag treatment.Based on this,a two-step slag deoxidation process was optimized.The second step further reduced the FeO content.On the other hand,the CaO/Al2O3(C/A)ratio in the refining slag must be controlled,because it affects the FeO activity and inclusion absorption capacity of the slag.The results suggest that the C/A ratio of 1.2–1.5 and the FeO content of\6%are beneficial to refine IF steel.

Cold Simulation of Oxygen Transfer Rate in BOF

By measuring the mass transfer coefficient of benzoic acid between water and oil, the oxygen transfer rate in BOF bath was researched, and the influence of top and bottom blowing gas flow rate on the mass transfer between metal and slag was discussed. The results show that with increasing the bottom blowing gas flow rate under the conditions of fixed top blowing, the mass transfer rate evidently increases, and the influence of fixed top blowing on the mass transfer is 10% of bottom blowing. The stirring intensity was determined as a function of top blowing gas flow rate, bottom blowing gas flow rate, and lance height. The equation of the mass transfer coefficient between metal and slag was established. The relationship between the emulsification ratio of oil to water and the bottom blowing gas flow rate under the conditions of top and bottom blowing was obtained. The result shows that with the increase in the bottom blowing gas flow rate, the emulsification ratio increases linearly, which increases the mass transfer rate of benzoic acid between water and oil.

The effect of bubble plume on oxygen transfer for moving bed biofilm reactor

The movement of the bubble plume plays an important role in the operation of a moving bed biofilm reactor （MBBR）, and it directly affects the contact and the mixture of the gas-liquid-solid phases in the aeration tank and also the oxygen transfer from the gas phase to the liquid phase. In this study, the velocity field is determined by a 4-frame PTV as well as the time-averaged and timedependent velocity distributions. The velocity distribution of the bubble plume is analyzed to evaluate the operating efficiency of the MBBR. The results show that the aeration rate is one of the main factors that sway the velocity distribution of the bubble plumes and affect the operating efficiency of the reactor.

Evaluation of oxygen transfer parameters of fine-bubble aeration system in plug flow aeration tank of wastewater treatment plant

Knowledge of the oxygen mass transfer of aerators under operational conditions in a full-scale wastewater treatment plant （WWTP） is meaningful for the optimization of WWTP, however, scarce to best of our knowledge. Through analyzing a plug flow aeration tank in the Lucun WWTP, in Wuxi, China, the oxygenation capacity of fine-bubble aerators under process conditions have been measured in- situ using the off-gas method and the non-steady-state method. The off-gas method demonstrated that the aerators in different corridors in the aeration tank of WWTP had significantly different oxygen transfer performance; furthermore, the aerators in the same corridor shared almost equal oxygen transfer performance over the course of a day. Results measured by the two methods showed that the oxygen transfer performance of fine-bubble aerators in the aeration tank decreased dramatically compared with that in the clean water. The loss of oxygen transfer coefficient was over 50% under low-aeration conditions （aeration amount 〈 0.67 Nm 3 /hr）. However, as the aeration amount reached 0.96 Nm 3 /hr, the discrepancy of oxygen transfer between the process condition and clean water was negligible. The analysis also indicated that the non-steady-state and off-gas methods resulted in comparable estimates of oxygen transfer parameters for the aerators under process conditions.

Theoretical analysis and experimental study of oxygen transfer under regular and non-breaking waves

The dissolved oxygen concentration is an important index of water quality, and the atmosphere is one of the important sources of the dissolved oxygen. In this paper, the mass conservation law and the dimensional analysis method are employed to study the oxygen transfer under regular and non-breaking waves, and a unified oxygen transfer coefficient equation is obtained with consideration of the effect of kinetic energy and wave period. An oxygen transfer experiment for the intermediate depth water wave is performed to measure the wave parameters and the dissolved oxygen concentration. The experimental data and the least squares method are used to determine the constant in the oxygen transfer coefficient equation. The experimental data and the previous reported data are also used to further validate the oxygen transfer coefficient, and the agreement is satisfactory. The unified equation shows that the oxygen transfer coefficient increases with the increase of a parameter coupled with the wave height and the wave length, but it decreases with the increase of the wave period, which has a much greater influence on the oxygen transfer coefficient than the coupled parameter.

Determination of real-time oxygen transfer rate based on an electrochemical method

The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys.The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;however,it is difficult to be studied in situ.Here,a new method of measuring the oxygen transfer rate at the gas-slag and slag-metal interfaces was reported based on electrochemical analyses.The interfacial oxygen transfer rate in the smelting process of Inconel 718 superalloy was investigated at 1723,1773,1823,and 1873 K.The experimental results show that the electrochemical method can measure the real-time oxygen content;hence,this method is promising in controlling the oxygen content in alloys.As the temperature increased,both the equilibrium oxygen content and the rate of oxygen absorption increased significantly,and the increase was the most obvious when the temperature was 1873 K.The possible reason is that the increase in temperature weakens the mass transfer resistance of the electric double layer at the interface,thus accelerating the oxygen transfer rate.

Oxygen transfer characteristics of bubbly jet in regular waves

The dissolved oxygen level is an important index of the water environment,and in this paper,the oxygen transfer of the bubbly jet in regular waves is investigated numerically and experimentally.The Reynolds-averaged Navier-Stokes equations,the re-normalisation group k-e equations,and the volume of fluid(VOF)technique are used along with a 2-D CFD model to simulate the wave and bubble motions as well as the turbulence,and a dissolved oxygen transport equation is used to model the oxygen transfer behavior both through the bubbly interface and the wave surface.A series of experiments are conducted to validate the mathematical model,with good agreement.In addition,a group of dimensionless parameters are defined from the wave parameter and the aeration parameter,and their relationships with the total oxygen transfer coefficient are explored.Furthermore,the dimensional analysis and the least squares methods are used to derive simple prediction formulas for the total oxygen transfer coefficient,and they are validated with the related experimental data.

Effects of carrier-attached biofilm on oxygen transfer efficiency in a moving bed biofilm reactor

Three laboratory-scale moving bed biofilm reactors （MBBR） with different carrier filling ratios ranging from 40% to 60% were used to study the effects of carrier-attached biofilm on oxygen transfer efficiency. In this study, we evaluated the performance of three MBBRs in degrading chemical oxygen demand and ammonia. The three reactors removed more than 95% of NH4^＋ -N at an air flow-rate of 60L·h^-1. The standard oxygen transfer efficiency （αSOTE） of the three reactors was also investigated at air flow-rates ranging from 60 to 100L·h^-1. These results were compared to αSOTE of wastewater with a clean carrier （no biofilm attached）. Results showed that under. these process conditions, αSOTE decreased by approximately 70% as compared to αSOTE of wastewater at a different carrier-filling ratio. This indicated that the biofilm attached to the cartier had a negative effect on αSOTE. Mechanism analysis showed that the main inhibiting effects were related to biofilm flocculants and soluble microbial product （SMP）. Biofilm flocs could decrease otSOTE by about 20%, and SMP could decrease aαSOTE by 30%--50%.

Effects of CeCl_3 on Energy Transfer and Oxygen Evolution in Spinach Photosystem Ⅱ

Due to 4f electron characteristics and alternation valence, cerium involved in an oxidation-reduction reaction in plant, closely relating to photosynthesis. Our studies proved that cerium could promote photosynthesis and greatly improve spinach growth. However, the mechanism of promoting energy transfer and conversion by cerium remains unclear. Here we reported that the effects of Ce^3＋ on energy transfer and oxygen evolution in photosystem Ⅱ （PS Ⅱ ） isolated from spinach, which was related to 4f electron characteristics and alternation valence in Ce molecule. The methods of absorption spectrum, fluorescence spectrum were used in the research. Results showed that Ce^3＋ treatment at low concentration could suitably change PS Ⅱ mieroenvironment, increase the absorbance of visible light, improve the energy transfer among amino acids within PS Ⅱ protein-pigment complex, and accelerate energy transport from tyrosine residue to chlorophyll a. In summary, the photochemical activity of PS Ⅱ （fluorescence quantum yield） and its oxygen evolving rate were enhanced by Ce^3＋.

Oxygen Atom Transfer Reaction of Manganese-oxo Corrole toward Dimethyl Sulfide: a Density Functional Study

The effects of axial ligand on the oxygen atom transfer(OAT)reaction from 5,10,15-tris(pentafluorophenyl)corrole((tpfc)MnVO)to dimethyl sulfide(DMS)have been investigated by density functional theory(DFT)calculations.Imidazole(Im),4-methylimidazole(4-MI)and pyridine(Py)were selected as the axial ligands.The results revealed that the axial ligand can form coordinate bond with(tpfc)MnVO in the transition state(TS)of the OAT reaction.The axial coordination favored charge transferring from(tpfc)MnVO to DMS,and weakened the Mn≡O bond in both singlet and triplet states.Furthermore,axial coordination can reduce the energy barrier of neutral(tpfc)MnVO from 23.62 kJ·mol^-1 to less than 3 kJ·mol^-1 in the triplet state,which is significantly lower than in the singlet state.This makes(tpfc)MnVO tend to direct the OAT reaction via triplet state pathway.On the other hand,the energy barriers of[(tpfc)MnVIO]+species from disproportionation pathway increased from 1.26 to 33.95 kJ·mol^-1 in a doublet state.This suggests axial ligands were conducive for direct(tpfc)MnVO OAT reaction pathway.

Heat Transfer Characteristics of Boiler Convective Heating Surface Under Pressurized Oxygen-fuel Combustion Conditions

增压富氧燃烧是一项极具前景的减排CO2新技术。对增压富氧燃烧条件下,对流受热面换热特性进行研究具有重要的意义。该文以一台实际300MW等级机组煤粉锅炉为计算对象,采用维里方程及Chun等的计算方法计算确定增压富氧燃烧烟气物性,采用宽带关联k模型计算富氧燃烧烟气辐射特性。进行了常规空气燃烧以及φ（O2）：φ（CO2）=21：79、φ（O2）：φ（CO2）=30：70两种比例的0.1、0.5、1.0、1.5、6 MPa五种压力下增压富氧燃烧各对流受热面的热力计算,分析了增压富氧燃烧条件烟气压力变化对各受热面换热特性的影响。研究结果表明：随烟气压力的升高,烟气流速下降,但烟气的Re却基本保持不变,对流换热系数有所增加。增压富氧燃烧烟气的辐射换热系数比空气燃烧烟气辐射换热系数大。实现同样的换热量,增压富氧燃烧条件下（φ（O2）：φ（CO2）=21：79、φ（O2）：φ（CO2）=30：70）对流受热面所需换热面积比常规空气燃烧条件下少。

STUDIES OF DISSOLVED OXYGEN IN PRODUCTION OF D-RIBOSE BY FERMENTATION

This paper mainly dealt with the dissolved oxygen in production of D-ribose by fermentation. The oxygen transfer coefficients of common flask, buffed flask and jar fermentor were determined.

Experimental Study of Dissolved Oxygen Transport by Regular Waves Through a Perforated Breakwater

The perforated breakwater is an environmentally friendly coastal structure, and dissolved oxygen concentration levels are an important index to denote water quality. In this paper, oxygen transport experiments with regular waves through a vertical perforated breakwater were conducted. The oxygen scavenger method was used to reduce the dissolved oxygen concentration of inner water body with the chemicals Na2SO3 and COC12. The dissolved oxygen concentration and wave parameters of 36 experimental scenarios were measured with different perforated arrangements and wave conditions. It was found that the oxygen transfer coefficient through wave surface, K1α1, is much lower than the oxygen transport coefficient through the perforated breakwater, K2α2. If the effect of K1α1 is not considered, the dissolved oxygen concentration computation for inner water body will not be greatly affected. Considering the effect of a permeable area ratio a, relative location parameter of perforations 6 and wave period T, the aforementioned data of 30 experimental scenarios, the dimensional analysis and the least squares method were used to derive an equation of K2α2 （K2α2=0.0042aσ56δ2T1）. It was validated with 6 other experimental scenarios data, which indicates an approximate agreement. Therefore, this equation can be used to compute the DO concentration caused by the water transport through perforated breakwater.

The element transfer behavior of gas pool coupled activating TIG welding

This paper deals with a novel dual shield TIG welding method named gas pool coupled activating TIG( GPCA-TIG)welding. The welding method divides the shielding gas into two layers. Inert gas such as Ar is adopted as the inner layer gas to protect the tungsten electrode and the molten pool metal. Pure O_2,N_2 or mixture of them are used as the outer layer gas to increase the weld penetration and improve the low temperature toughness of weld metal. Through analyzing the interaction between outer gas and arc and the distributions and existing forms of oxygen and nitrogen elements,the transfer behaviors of nitrogen and oxygen from arc to pool were investigated. The results show that,the interaction between the outer gas and arc plasma makes the arc slightly constrict. The incoming oxygen enriches on the molten pool surface and exists in the form of iron oxide,chromium oxide,manganese oxide and silicon oxygen compounds. The incoming nitrogen evenly distributes in the molten pool and exists in the form of nitrogen atom.

Atmospheric Pressure Cold Argon/Oxygen Plasma Jet Assisted by Preionization of Syringe Needle Electrode

An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid barrier-jet was shown to generate uniform discharge with a lower breakdown voltage and a relatively low gas temperature varying from 390 K to 440 K, even when the vol.% oxygen in argon was up to 6%. Utilizing the actinometry method, the concentration of atomic oxygen was estimated to be about in an orders of magnitude of 10^17 cm^-3. The argon/oxygen plasma jet was then employed to clean out heat transfer oil, with a maximum cleaning rate of 0.1 mm/s achieved.

Useful and Unique Descriptions of Tropospheric Processes Which Produce Oxygen and Thereafter Give Birth to Equatorial Electro-Jets

Formation of negative static charges (e-) throughout troposphere is a natural phenomenon revealed by some weather events such as storms and lightning flashes that accompany thunderclouds. This climatic phenomenon (formation of negative charge in that case) has long been considered as physical phenomena of very small space-time scales. Now we have good reasons to say that this perception of troposphere electrical status is totally meaningless. Indeed, it is now easy to show that significant numbers of electrons are provided to troposphere at each appearance of a thunderstorm (or a lightning flash). Thereafter, movement implemented in the troposphere by winds (e.g., West African aerojet) contributes to the formation of low altitudes Electrojets (e.g., West African Equatorial Aerojet gives birth to West African Equatorial Electrojet). The existence of Low Layers Equatorial Electrojets (LL-EEJ) was totally unknown by the first theorists who have studied the Earth’s Ionosphere Plasma Physics and Electrodynamics. This mistake has led their followers to many questions unanswered in their attempt to explain the longitudinal and seasonal variations of observed EEJ. In this paper, we will provide many useful explanations on the manner in which clouds provide oxygen to troposphere and thereafter trigger negative static charges (e-) throughout both troposphere and ionosphere. Indeed, this paper also explains how, opportunely, the ITF (inter tropical front) plays the role of the tap which facilitates oxygen transfer from troposphere to ionosphere. Detailed studies on the Earth’s troposphere plasma physics and electrodynamics are impatiently awaited.