Simple and universal method in designs of high-efficiency diffractive optical elements for spectrum separation and beam concentration

Diffractive optical elements（DOEs） with spectrum separation and beam concentration（SSBC） functions have important applications in solar cell systems. With the SSBC DOEs, the sunlight radiation is divided into several wave bands so as to be effectively absorbed by photovoltaic materials with different band gaps. A new method is proposed for designing high-efficiency SSBC DOEs, which is physically simple, numerically fast, and universally applicable. The SSBC DOEs are designed by the new design method, and their performances are analyzed by the Fresnel diffraction integral method.The new design method takes two advantages over the previous design method. Firstly, the optical focusing efficiency is heightened by up to 10%. Secondly, focal positions of all the designed wavelengths can be designated arbitrarily and independently. It is believed that the designed SSBC DOEs should have practical applications to solar cell systems.

Determination of optimal grid opening width for herringbone water-sediment separation structures based on sediment separation efficiency

The herringbone water-sediment separation structure(HWSSS) was developed to prevent debris flows. This paper mainly focuses on evaluating the sediment separation efficiency of HWSSS in debris flow prevention and determining the grid opening width D, a crucial structure parameter for HWSSS design. Theoretical analysis on the total sediment separation rate Pt reveals that the efficiency of sediment separation is much related with sediment grain size distribution(GSD) and grid opening width. The lower limit of Pt is deduced from the perspective of safety consideration by transforming debris flow into sediment-laden flow. Hydraulic model tests were carried out. Based on the regression analysis of the experimental data, the quantitative relationships between Pt and D and GSD characteristic values were finally established. A procedure for determining optimal grid opening width is proposed based on these analyses. These results are of significance in evaluating sediment separation effect by HWSSS in debris flow prevention and contribute to a more explicit methodology for design of HWSSS.

Separation efficiency of alumina particles in Al melt under high frequency magnetic field

The effects of separation time and magnetic induction intensity on the separation efficiency of alumina particles with diameters varying from 30 to 200 μm in aluminum melt were investigated. The experimental results show that the particle-accumulated layer is formed in the periphery of the solidified specimen when the diameter of the separated molten metal, the magnetic induction intensity and the separation time are 10 mm, 0.04 T and 1 s, respectively. When the separation time is 2 s, the particle-accumulated layer can be observed obviously and the separation efficiency is about 80%. There are few alumina particles in the inner of the solidified specimen when the separation time is 3 s. The separation efficiency higher than 85% can be achieved when the separation time is longer than 3 s. When the magnetic induction intensity is 0.06 T, the visible particle-accumulated layer can be formed in 1 s and the separation efficiency is higher than 95%. The experimental results were compared with the calculated results at last.

Experimental study on sand particles accumulation,migration and separation efficiency in slug catcher

Sand production often leads to the failure of production equipment on offshore platform.Therefore,a new idea has been put forward,which is installing cyclone or baffle in the internal of the slug catcher for better sand control.In this paper,an experimental study is presented,which mainly includes sand particles accumulation shape,migration law and separation performance.The results suggest that the accumulation area is mainly divided into two zones:the crowded settlement zone and the free settlement zone.The crowded settlement zone has a special shape,which can be characterized by two parameters:accumulation length and accumulation angle.Axial sampling analysis shows obvious particle classification.Median particle size decreases with the increase of the axial distance,and the range of particle size distribution narrows gradually.The separation experiment shows that the gas velocity has the greatest influence on the separation efficiency.When the gas velocity is 14 m·s^ 1,the separation efficiency drops sharply,which can be abated by installing cyclone separator.In addition,the separation efficiency tends to be a constant under different gas velocities by installing baffle with appropriate height.Then the effectiveness and rationality of installing internal components can be strongly proved.All these provide important guidance for maximizing the sand control function of the slug catcher.

Numerical Study of Steam-Water Separators with Wave-type Vanes

Droplet behavior in the wave-type flow channel is discussed, especially with the secondary .droplet generation due to impingement of droplets on the wall considered. A numerical method is suggested to simulate tile droplet behavior in the flow field. Calculations are compared With experimental data on the ; pressure drop and separating efficiency. Good agreement exists between the calculations and air-water experiments. The numerical method developed gives a reasonable description of the droplet deposition and secondary droplet generation, and it can be applied to predict the performance of wave-type vane separators.

Efficiency of Plate Separators for Dispersed Liquid-Liquid Systems

The basic flow model of laminar flow field and the trajectory model of dispersed phase drops are derived. Based on the comparable volumetric flow rate, the dispersed flow rate can be linearly discretized. Consequently, the trajectory of a droplet in the channel can be tracked, and the trajectories of all drops are observed in order to statistically analyse the drops for capture or entrainment. Therefore, in terms of theoretical model of motion, the stratified two phase flow systems are studied in the mixture of nitrobenzene and concentrated sulfuric acid. The analytical results indicate that the trajectories of droplets of different diameters are different at the same location. The larger droplets can help to promote the efficiency of plate separators. The thickness of trickling film has a significant influence on the efficiency of numerical simulation when the concentration of the dispersed phase is greater than 10%. So the modification of thickness of trickling film can help to get the real flow field efficiency. The low flow rate lowers the average Renolds number so that the lighter phase droplets have sufficient time to interact with the trickling film. It is an indispensable factor for predicting efficiency that coalesced drops flow off inclined plates together with trickling films. A comparison confirms that the simulation results are in good agreement with the experiment results.

Separation of galena and chalcopyrite using the difference in their surface acid corrosion characteristics

Galena(PbS)and chalcopyrite(CuFeS_(2))are sulfide minerals that exhibit good floatability characteristics.Thus,efficiently separating them via common flotation is challenging.Herein,a new method of surface sulfuric acid corrosion in conjunction with flotation separation was proposed,and the efficient separation of galena and chalcopyrite was successfully realized.Contact angle test results showed a substantial decrease in surface contact angle and a selective inhibition of surface floatability for corroded galena.Meanwhile,the contact angle and floatability of corroded chalcopyrite remained almost unaffected.Scanning electron microscope results confirmed that sulfuric acid corrosion led to the formation of a dense oxide layer on the galena surface,whereas the chalcopyrite surface remained unaltered.X-ray photoelectron spectroscopy results showed that the chemical state of S^(2-)on the surface of corroded galena was oxidized to SO_(4)^(2-).A layer of hydrophilic PbSO4was formed on the surface,leading to a sharp decrease in galena floatability.Meanwhile,new hydrophobic CuS_(2),CuS,and Cu_(1-x)Fe_(1-y)S_(2-z)species exhibiting good floatability were generated on the chalcopyrite surface.Finally,theoretical analysis results were further verified by corrosion–flotation separation experiments.The galena–chalcopyrite mixture was completely separated via flotation separation under appropriate corrosion acidity,corrosion temperature,and corrosion time.A novel approach has been outlined in this study,providing potential applications in the efficient separation of refractory copper–lead sulfide ore.

Research on High-Efficiency Cyclone Separators and Their Optimum Design

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Industrial Progress:New Energy-Efficient Absorbents for the CO_(2) Separation from Natural Gas,Syngas and Flue Gas

The CO2 separation from natural gas, syngas or flue gas represents an important industrial field of applications. An economic and energy-efficient CO2 separation from these gas streams is a prerequisite for sustainable industry contributions to the megatrends resource efficiency and globalization of technologies. One way of reducing operational expenditure for these separation processes is the development of better performing CO2 absorbents. Although a number of absorbents for the separation of CO2 from process gas streams exist, the need for the development of CO2 absorbents with an improved absorption performance, less corrosion and foaming, no nitrosamine formation, lower energy requirement and therefore less operational expenditure remains. Recent industrial activities have led to the development of novel high-performance CO2 scrubbing agents that can be employed in numerous industrial processes such as natural gas treatment, purification of syngas and the scrubbing of flue gas. The objective of this paper is to introduce these new high-performance scrubbing agents and to compare their performance with other state-of-the-art absorbents. It turned out, that the evaluated absorbents offer high cyclic capacities in the range of 2.4 to 2.6 mol CO2/kg absorbent and low absorption enthalpies (–30 kJ/mol) allowing for distinctive savings in the regeneration energy of the absorbent. Calculations with the modified Kremser model resulted in a reduction of the specific reboiler heat duty of 55%. Furthermore, the absorbents are less corrosive than standard amines as indicated by the measured corrosion rates of 0.21 mm/y versus 1.18 mm/y for a piperazine/methyldiethanolamine mixture. Based on new experimental results it is shown how substantial savings in operational and capital expenditure can be realized due to favorable absorbent properties. The novel high-performance CO2 system solutions meet recent industrial absorbent requirements and allow for more efficient or new CO2 separation processes.

Efficient Particle Separation in Microfluid Channel with Inhomogeneous Magnetic Field

In this paper, we combined magnetostatics and laminar flow in microfluidics and studied a particle separation scheme employing magnetophoretic force in inhomogeneous magnetic field. A detailed model and analysis is shown and the proposed scheme is capable of efficiently separating magnetic particles with different permeability and sizes. The method shows a way to separate efficient particles and could potentially be implemented in biological and chemical systems.

THEORETICAL INVESTIGATION ON BY-ONLY-CURRENT ELECTROMAGNETIC SEPARATION OF INCLUSION FROM MOLTEN METALS

The electromagnetic field under applied AC and DC current in round and rectangular pipe was systematically investigated, then a concept of 'equivalent current density' was proposed for evaluating the inhomogeneous electromagnetic pinch force, and the mono-component removal efficiency and the overall removal efficiency of inclusion were formulated. It is founded that flat pipe is superior to round pipe for the electromagnetic removal of inclusion, and DC current can get a higher removal efficiency than A C current due to absence of skin phenomenon. Under usual condition, a removal efficiency of 52% for 10μm inclusion or more than 92% for 20μm inclusion can be achieved by imposing a current density of 3×106A/m2 in a flat pipe.

Experimental Investigation on Heat Exchange and Separation Performance of an Annular Structured Internal Heat-integrated Distillation Column

In this paper heat exchange coefficient and separation efficiency of an annular structured internal heat-integrated distillation column(HIDi C) were experimentally measured. About 50% heat of the inner column could be transferred to the outer column. The overall heat exchange coefficient decreased with an increase in pressure ratio of the inner column and the outer column, but was little affected by the F-factor. The increase of the pressure ratio decreased obviously the separation efficiency of the outer column but had little effect on that of the inner column.

Evaluation of gas-liquid separation performance of natural gas filters

Fibrous filters are often used to remove contaminants including both dusts and liquid droplets from natural gas. This paper aims to evaluate the gas-liquid separation performance of three types of cartridge filters used in the West-East natural gas transmission project. The comparison of the original pressure drop of clean filters and the evolution of pressure drop as liquid droplets deposited in the filter media are described. The original pressure drops of these filters were similar but the pressure drops at a steady state were different. Fractional efficiency was used to study the separation performance of cartridge filters. Droplets at the outlet of the filters had small diameters, no more than 3 μm, but were very numerous. The effect of filtration velocity on gas-liquid separation performance was analyzed. Higher filtration velocity indicated better gas-liquid separation performance. Finally the quality factor related to pressure drop and filtration efficiency was applied to evaluate the gas-liquid separation performance.

Recent strategies to enhance the efficiency of hematite photoanodes in photoelectrochemical water splitting

Photoelectrochemical(PEC)water splitting is one of the most promising approaches toward achieving the conversion of solar energy to hydrogen.Hematite is a widely applied photoanode material in PEC water splitting because of its appropriate band structure,non-toxicity,high stability,and low cost.Nevertheless,its relatively low photochemical conversion efficiency limits its application,and enhancing its PEC water splitting efficiency remains a challenge.Consequently,increasing efforts have been rendered toward improving the performance of hematite photoanodes.The entire PEC water splitting efficiency typically includes three parts:the photon absorption efficiency,the separation efficiency of the semiconductor bulk,and the surface injection efficiency.This review briefly discusses the recent advances in studies on hematite photoanodes for water splitting,and through the enhancement of the three above-mentioned efficiencies,the corresponding strategies toward improving the PEC performance of hematite are comprehensively discussed and summarized.

Electromagnetic separation of primary iron-rich phases from aluminum-silicon melt

The difference of conductivity between primary iron-rich phases and aluminum melt has been used to separate them by electromagnetic force (EMF) which is induced by imposing a direct electric current and a steady magnetic field in molten Al-Si alloy. Theoretical analysis and experiments on self-designed electromagnetic separation indicates that primary needle-like β phases are difficult to separate; while primary α iron-rich phases can be separated by electromagnetic separation. Primary iron-rich phases have been removed from the melt successfully when the molten metal flows horizontally through separation channel. The iron content is reduced from 1.13% to 0.41%.

Continuous Separation of Inclusions from Aluminum Melt Flowing in a Circular Pipe using a High Frequency Magnetic Field

The continuous separation of inclusions from aluminum melt flowing in a circular pipe using a high frequency magnetic field was investigated both theoretically and experimentally. The separation efficiency was calculated based on the trajectory method and compared with experimental results. It is found that the separation efficiency is a function ofnondimensional parameters ti . The effective way to improve the separation efficiency is to increase the effective magnetic flux density and decrease the pipe radius, and the value of should be kept about 2 in order to obtain the optimum separation efficiency.

SEPARATION CHARACTERISTICS OF THE HYDROCYCLONE WITH A CENTRAL CONE AND ANNULAR TEETH

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Flat Belt Separation System under Slat in Fattening Pig Housing: Effect of Belt Slope Angle

In this study, the separation and drying efficiency of the excreta, separated into solid and liquid fraction by a flat conveyor belt under a partial slatted floor in a facility for fattening pigs, was determined. Two transverse slope angles (4&#176 and 6&#176) for the flat belts were used, in a trial with pigs from 20.61 to 117.83 kg of live weight (LW), and the sample size was 7 pigs per pen, 42 pigs per room. The flat belt was more efficient with 6° than with 4° slope angle (32.65% vs. 29.91% dry matter content of solid fraction during the whole fattening period, respectively;P &#176 than for the 4&#176 (1.4137 vs. 1.3030, during the whole fattening period;P &#176, this efficiency was not improved in finishing period -83.40 to 117.83 kg LW (two extractions per day) with regard to the growth period -20.61 to 83.40 kg LW (one extraction per day). Meanwhile, with 4&#176 it did improved. The ventilation system underneath slat seems to play a key role in the obtained results.

Structure Optimization of a Horizontal Gas-Solid Rapid Separation Device

To meet the requirements for fast and efficient gas-solid separation at the outlet of a gas-solid concurrent downflow fluidized bed(downer),a new horizontal gas-solid rapid separator was designed based on the joint action of centrifugal and inertial forces.Under the same experimental conditions,a fluid catalytic cracking(FCC)catalyst was used as the material(with a particle density of 1500 kg/m3 and a mean particle size of 45.8μm)to experimentally investigate the effects of the insertion length of gas outlet pipe,the bypass cylinder,the gas outlet direction,and the secondary separation structure on the separator performance.The results showed that with an inlet gas flow rate of 14.5 m/s and a gas phase solid content of 60―835 g/m3,the downer system achieved a gas-solid separation efficiency of above 99.5%,with the separator’s pressure drop within 1846 Pa(when the separator included a bypass cylinder and a secondary separation structure with a proper insertion length of gas outlet pipe).

Separation of Oil Phase from Dilute Oil/Water Emulsion in Confined Space Apparatus

A miniature process for separating the oil phase from dilute oil/water emulsion is developed.This process applies a confined space apparatus,which is a thin flow channel made of two parallel plastic plates.The space between the two plates is rather narrow to improve the collisions between oil droplets and the plate surface.Oil droplets have an affinity for the plate surface and thus are captured,and then coalesce onto the surface.The droplet size distribution of the residual emulsion resulted from the separation process is remarkably changed.The oil layer on the plate weakens the further separation of oil droplets from the emulsion.Three types of plate materials,polypropylene(PP),polytetrafluoroethylene(PTFE) and nylon 66,were used.It is found that PP is the best in terms of the oil separation efficiency and nylon 66 is the poorest.The interaction between droplets in the emulsion and plate surface is indicated by the spreading coefficient of oil droplet on the plate in aqueous environment,and the influences of formed oil layer and plate material on the separation efficiency are discussed.