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Experimental and numerical investigations on micromixing performance of multi-orifice cross-flow jet mixers
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作者 Hang Yang Zhaojin Lu +4 位作者 Likun Ma Wei Yin Bingjie Wang Zhishan Bai Xiaoyong Yang 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第6期63-72,共10页
Multi-orifice cross-flow jet mixers(MOCJMs)are used in various industrial applications due to their excellent mixing efficiency,but few studies have focused on the micromixing performance of MOCJMs.Herein,the flow cha... Multi-orifice cross-flow jet mixers(MOCJMs)are used in various industrial applications due to their excellent mixing efficiency,but few studies have focused on the micromixing performance of MOCJMs.Herein,the flow characteristics and micromixing performance inside the MOCJM were investigated using experiments and computational fluid dynamics(CFD)simulations based on the Villermaux/Dushman system and the finite-rate/modified eddy-dissipation model.The optimal A value was correlated with the characteristic parameters of MOCJMs to develop a CFD calculation method applicable to the study of the micromixing performance of the MOCJMs.Then the micromixing efficiency was evaluated using the segregation index XS,and the effects of operational and geometric parameters such as mixing flow Reynolds number(ReM),flow ratio(RF),total jet area(ST),the number of jet orifices(n),and outlet configuration on the micromixing efficiency were investigated.It was found that the intensive turbulent region generated by interactions between jets,as well as between jets and crossflows,facilitated rapid reactions.XS decreased with increasing ReM and decreasing RF.Furthermore,MOCJMs with lower ST,four jet orifices,and the narrower outlet configuration demonstrated a better micromixing efficiency.This study contributes to a deeper understanding of the micromixing performance of MOCJMs and provides valuable guidance for their design,optimization,and industrial application. 展开更多
关键词 Multi-orifice cross-flow jet mixer Micromixing performance Finite-rate/modified eddy dissipation model Computational fluid dynamics Villermaux/Dushman reaction
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Fuzzy Comprehensive Analysis of Static Mixers Used for Selective Catalytic Reduction in Diesel Engines
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作者 Xin Luan Guoqing Su +1 位作者 Hailong Chen Min Kuang 《Fluid Dynamics & Materials Processing》 EI 2024年第11期2459-2473,共15页
The proper selection of a relevant mixer generally requires an effective assessment of several models against theapplication requirements. This is a complex task, as traditional evaluation methods generally focus only... The proper selection of a relevant mixer generally requires an effective assessment of several models against theapplication requirements. This is a complex task, as traditional evaluation methods generally focus only on a single aspect of performance, such as pressure loss, mixing characteristics, or heat transfer. This study assesses aurea-based selective catalytic reduction (SCR) system installed on a ship, where the installation space is limitedand the distance between the urea aqueous solution injection position and the reactor is low;therefore, the staticmixer installed in this pipeline has special performance requirements. In particular, four evaluation indices areused in this study: The B value, C value, pressure loss correction factor (Z′), and the ratio of the required distanceto the equivalent diameter of the pipe (LV/D) when the velocity field after the mixer attains uniformity. Six typesof static mixers were simulated with varying concentrations, flow speeds, and positions. A fuzzy comprehensiveevaluation method was introduced to evaluate and compare the related advantages and disadvantages. The resultsshowed that 1) mixing performance was related to the shape of the mixer and had no direct relationship with flowvelocity. 2) For the same mixer position, the lower the urea concentration, the greater the difficulty of evenly mixing the solution. 3) At a constant urea concentration, the mixing performance improved when the mixer was closer to the injection inlet. 4) The installation of a GK mixer in the SCR system of a 9L20C diesel engine was best. 展开更多
关键词 Static mixer fuzzy comprehensive evaluation coefficient of variation mixing performance
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Optimal Design and Experimental Study of Tightly Coupled SCR Mixers for Diesel Engines
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作者 Jianhua Zhang Wen Sun Zhijun Li 《Energy Engineering》 EI 2024年第10期2893-2906,共14页
Two types of tightly coupled Selective Catalytic Reduction(SCR)mixers were designed in this study,namely Mixer 1 integrated with an SCR catalyst and Mixer 2 arranged separately.Computational Fluid Dynamics(CFD)softwar... Two types of tightly coupled Selective Catalytic Reduction(SCR)mixers were designed in this study,namely Mixer 1 integrated with an SCR catalyst and Mixer 2 arranged separately.Computational Fluid Dynamics(CFD)software was utilized to model the gas flow,spraying,and pyrolysis reaction of the aqueous urea solution in the tightly coupled SCR system.The parameters of gas flow velocity uniformity and ammonia distribution uniformity were simulated and calculated for both Mixer 1 and Mixer 2 in the tightly coupled SCR system to compare their advantages and disadvantages.The simulation results indicated that Mixer 1 exhibited a gas velocity uniformity of 0.972 and an ammonia distribution uniformity of 0.817,whereas Mixer 2 demonstrated a gas velocity uniformity of 0.988 and an ammonia distribution uniformity of 0.964.Mixer 2 performed better in the simulation analysis.Furthermore,a 3D-printed prototype of Mixer 2 was manufactured and installed on an engine test bench to investigate ammonia distribution uniformity and NOX conversion efficiency.The experimental investigations yielded the following findings:1)The ammonia distribution uniformity of Mixer 2 was measured as 0.976,which closely aligned with the simulation result of 0.964,with a deviation of 1.2%from the model calculations;2)As exhaust temperature increased,the ammonia distribution uniformity gradually improved,while an increase in exhaust flow rate resulted in a decrease in ammonia distribution uniformity;3)When utilizing Mixer 2,the NOX conversion efficiency reached 84.7%at an exhaust temperature of 200°C and 97.4%at 250°C.Within the exhaust temperature range of 300°C to 450°C,the NOX conversion efficiency remained above 98%.This study proposed two innovative mixer structures,conducted simulation analysis,and performed performance testing.The research outcomes indicated that the separately arranged Mixer 2 exhibited superior performance.The tightly coupled SCR systemequippedwith Mixer 2 achieved excellent levels of gas velocity uniformity,ammonia distribution uniformity,and NOX conversion efficiency.These findings can serve as valuable references for the design and development of ultra-low emission after-treatment systems for diesel engines in the field of diesel engine aftertreatment. 展开更多
关键词 Tightly coupled SCR MIXER ammonia distribution uniformity
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CFD simulation of hydrodynamics and mixing performance in dual shaft eccentric mixers 被引量:2
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作者 Songsong Wang Xia Xiong +5 位作者 Peiqiao Liu Qiongzhi Zhang Qian Zhang Changyuan Tao Yundong Wang Zuohua Liu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第10期297-309,共13页
This work aims to systematically study hydrodynamics and mixing characteristics of non-Newtonian fluid(carboxyl methyl cellulose,CMC)in dual shaft eccentric mixer.Fluid rheology was described by the power law rheologi... This work aims to systematically study hydrodynamics and mixing characteristics of non-Newtonian fluid(carboxyl methyl cellulose,CMC)in dual shaft eccentric mixer.Fluid rheology was described by the power law rheological model.Computational fluid dynamics was employed to simulate the velocity field and shear rate inside the stirred tank.The influence mechanism of the rotational modes,height difference between impellers,impeller eccentricities,and impeller types on the flow field have been well investigated.We studied the performance of different dual-shaft eccentric mixers at the constant power input with its fluid velocity profiles,average shear strain rate,mixing time and mixing energy.The counter-rotation mode shows better mixing performance than co-rotation mode,and greater eccentricity can shorten mixing time on the basis of same stirred condition.To intensify the hydrodynamic interaction between impellers and enhance the overall mixing performance of the dual shaft eccentric mixers,it is critical to have a reasonable combination of impellers and an appropriate spatial position of impellers. 展开更多
关键词 Dual shaft eccentric mixers Non-Newtonian fluid Mixing Laminar flow Computational fluid dynamics
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Low Voltage CMOS Gilbert Mixers for Bluetooth Transceiver 被引量:1
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作者 崔福良 马德群 +3 位作者 黄林 叶菁华 郭淦 洪志良 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2004年第9期1066-1073,共8页
Based on the analyses of the reported Gilbert mixers operating at low supply vol tage,a down-conversion mixer and an up-conversion mixer for 2.4GHz bluetooth transceiver are presented with the modified low voltage de... Based on the analyses of the reported Gilbert mixers operating at low supply vol tage,a down-conversion mixer and an up-conversion mixer for 2.4GHz bluetooth transceiver are presented with the modified low voltage design techniques,respe ctively.Feedback and current mirror techniques suitable for low voltage operatio n are used to improve the linearity of the up-conversion mixer,and folded-casc ode output stage is adopted to optimize the noise and conversion gain of the dow n-conversion mixer operating at low voltage.Based on 0.35μm CMOS technology,s imulations are performed with 2V supply voltage.The results show that 20dBm thir d-order intercept point (IIP3),87mV output signal amplitude are achieved for up -conversion mixer with about 3mA current;while 20dB conversion gain (CG),6.5nV /Hz input-referred noise,4.4dBm IIP3 are obtained for down-conversion mixer with about 3.5mA current. 展开更多
关键词 bluetooth transceiver low voltage MIXER
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CMOS Mixers for 2.4GHz WLAN Transceivers 被引量:2
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作者 池保勇 石秉学 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2003年第5期472-475,共4页
A down-conversion mixer and an up-conversion mixer for 2.4GHz WLAN transceivers are presented.The down-conversion mixer uses a class-AB input stage to get high linearity and to realize input impedance matching and sin... A down-conversion mixer and an up-conversion mixer for 2.4GHz WLAN transceivers are presented.The down-conversion mixer uses a class-AB input stage to get high linearity and to realize input impedance matching and single-ended to differential conversion.The mixers are implemented in 0.18μm CMOS process.The measured results are given to show their performance. 展开更多
关键词 WLAN transceivers MIXER Gilbert cell
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Synergistic and interference effects in coaxial mixers: Numerical analysis of the power consumption 被引量:1
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作者 Juan Huang Gance Dai 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第4期684-694,共11页
This paper is concerned with the design and application of coaxial mixers with the aid of analysis of interaction between each individual impeller. Two types of coaxial mixers pitched blade turbine(PBT)-helical ribbon... This paper is concerned with the design and application of coaxial mixers with the aid of analysis of interaction between each individual impeller. Two types of coaxial mixers pitched blade turbine(PBT)-helical ribbon(HR)and inner-outer HR operated in laminar regime were studied experimentally and numerically. The interaction implies synergistic and interference effects, which was revealed through the investigation of axial circulation rate, energy dissipation rate and power consumption. The influence factors including rotational speed ratio,rotating mode and impeller configuration were explored systematically. Quantitative analysis of power consumption involves three parameters: rate of variation in power consumption, interactive mode and ratio of power consumption. Analysis indicated that some important properties were embodied in the power curve.These properties are one-way and two-way interactions, critical speed ratio and dominant impeller. Finally, a new suggestion for power estimation was given. 展开更多
关键词 Numerical simulation Mixing Laminar flow Coaxial mixers Power consumption Interaction
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CFD modeling of immiscible liquids turbulent dispersion in Kenics static mixers: Focusing on droplet behavior 被引量:13
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作者 M.M.Haddadi S.H.Hosseini +1 位作者 D.Rashtchian G.Ahmadi 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第2期348-361,共14页
The present study is concerned with the computational fluid dynamics(CFD)simulation of turbulent dispersion of immiscible liquids,namely,water–silicone oil and water–benzene through Kenics static mixers using the Eu... The present study is concerned with the computational fluid dynamics(CFD)simulation of turbulent dispersion of immiscible liquids,namely,water–silicone oil and water–benzene through Kenics static mixers using the Eulerian–Eulerian and Eulerian–Lagrangian approaches of the ANSYS Fluent 16.0 software.To study the droplet size distribution(DSD),the Eulerian formulation incorporating a population balance model(PBM)was employed.For the Eulerian–Lagrangian approach,a discrete phase model(DPM)in conjunction with the Eulerian approach for continuous phase simulation was used to predict the residence time distribution(RTD)of droplets.In both approaches,a shear stress transport(SST)k-ωturbulence model was used.For validation purposes,the simulated results were compared with the experimental data and theoretical values for the Fanning friction factor,Sauter mean diameter and the mean residence time.The reliability of the computational model was further assessed by comparing the results with the available empirical correlations for Fanning friction factor and Sauter mean diameter.In addition,the influence of important geometrical and operational parameters,including the number of mixing elements and Weber number,was studied.It was found that the proposed models are capable of predicting the performance of the Kenics static mixer reasonably well. 展开更多
关键词 CFD Liquid–liquid dispersion Kenics static MIXER Eulerian–Eulerian APPROACH Eulerian–Lagrangian APPROACH
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Comparative analysis of different static mixers performance by CFD technique:An innovative mixer 被引量:12
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作者 M.M.Haddadi S.H.Hosseini +1 位作者 D.Rashtchian Martin Olazar 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第3期672-684,共13页
The flow and mixing behavior of two miscible liquids has been studied in an innovative static mixer by using CFD,with Reynolds numbers ranging from 20 to 160.The performance of the new mixer is compared with those of ... The flow and mixing behavior of two miscible liquids has been studied in an innovative static mixer by using CFD,with Reynolds numbers ranging from 20 to 160.The performance of the new mixer is compared with those of Kenics,SMX,and Komax static mixers.The pressure drop ratio(Z-factor),coefficient of variation(CoV),and extensional efficiency(α)features have been used to evaluate power consumption,distributive mixing,and dispersive mixing performances,respectively,in all mixers.The model is firstly validated based on experimental data measured for the pressure drop ratio and the coefficient of variation.CFD results are consistent with measured data and those obtained by available correlations in the literature.The new mixer shows a superior mixing performance compared to the other mixers. 展开更多
关键词 CFD New static mixer Coefficient of variation Pressure drop ratio
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Transfer Characteristics in Mechanically Stirred Airlift Loop Reactors with or without Static Mixers 被引量:5
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作者 吕效平 王延儒 时钧 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2000年第3期208-211,共4页
The mechanically stirred internal loop airlift reactors equipped with or without static mixers are devised for intensification of gas-liquid mass transfer rate. The influences of superficial gas velocity, agitation o... The mechanically stirred internal loop airlift reactors equipped with or without static mixers are devised for intensification of gas-liquid mass transfer rate. The influences of superficial gas velocity, agitation or static mixers on gas hold-up, mixing time, liquid circulating velocity and volumetric mass transfer coefficient have been investigated with tap water and carboxymethyl cellulose (CMC) aqueous solution. The experimental results indicate that mechanical agitation is more efficacious than static mixer in highly viscous media for improving mass transfer in airlift reactors. The empirical correlation of volumetric mass transfer coefficient with apparent viscosity, and energy consumption for mechanical agitation and aeration is developed. 展开更多
关键词 airlft loop reactor static mixer STIRRER HYDRODYNAMICS mass transfer
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PRESSURE DROP OF PSEUDO-PLASTIC FLUIDS IN STATIC MIXERS
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作者 许国军 冯连芳 +1 位作者 李允明 王凯 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 1997年第1期97-100,共4页
1 INTRODUCTIONUse of static mixers to process non-Newtonian fluids is quite commn.Data on thepressure drop of non-Newtonian fluids in Kenics static mixers are very useful in thedesign and engineering application of su... 1 INTRODUCTIONUse of static mixers to process non-Newtonian fluids is quite commn.Data on thepressure drop of non-Newtonian fluids in Kenics static mixers are very useful in thedesign and engineering application of such mixers.However,only a few studies con-cerned with the pressure drop of non-Newtonian fluid flow in static ndxers can befound in literature.Wilkinson and Cliff presented pressure drop data for aqueousglycerine solutions(Newtonian fluids)and aqueous 1% polyacrylamide solution showingviscoelastic behavior.They found no difference between the friction factors of 展开更多
关键词 STATIC MIXER pseudo-plastic fluid pressure DROP
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Design of Subharmonic Mixers above 100 GHz
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作者 Bo Zhang Ge Liu +4 位作者 Zhe Chen Xiao-Fan Yang Ning-Bo Chen San-Tong Wu Yong Fan 《Journal of Electronic Science and Technology》 CAS 2013年第4期349-351,共3页
This paper presents the design and simulation of several fixed-tuned sub-harmonic mixers cover frequencies from 110 GH to 130 GHz, 215 GH to 235 GHz, 310 GH to 350 GHz, and 400 GH to 440 GHz. Among them, 120 GHz, 225 ... This paper presents the design and simulation of several fixed-tuned sub-harmonic mixers cover frequencies from 110 GH to 130 GHz, 215 GH to 235 GHz, 310 GH to 350 GHz, and 400 GH to 440 GHz. Among them, 120 GHz, 225 GHz, 330 GHz subharmonic mixers are designed with flip-chipped planar schottky diode mounted onto a suspended quartz-based substrate, the 225 GHz and 425 GHz subharmonic mixers are GaAs membrane integrated, and the 115 GHz subharmonic mixer has been fabricated and tested already. 展开更多
关键词 Conversion loss planar schottkydiodes sub-harmonic mixer TERAHERTZ terahertzmonolithic integrated circuit membrane mixer.
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A numerical study of mixing intensification for highly viscous fluids in multistage rotor-stator mixers
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作者 Liying Chen Junheng Guo +3 位作者 Wenpeng Li Shuchun Zhao Wei Li Jinli Zhang 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2022年第7期218-230,共13页
How to achieve uniform mixing of highly viscous fluids with low energy consumption is a major industry demand and one of the hot spots of mixing research.A typical multistage rotor-stator mixer(MRSM)equipped with a di... How to achieve uniform mixing of highly viscous fluids with low energy consumption is a major industry demand and one of the hot spots of mixing research.A typical multistage rotor-stator mixer(MRSM)equipped with a distributor was investigated to disclose the effects on the mixing performance and power consumption for highly viscous fluids via numerical simulation,considering the influence factors associated with different geometric parameters of both MRSM and the distributor.The mixing index and power consumption are used to evaluate the performance of the mixers.The dimensionless correlations for the mixing index and the power consumption are established considering the factors including the flow rate,rotor speed,the number of mixing units.Adopting the optimized mixer with the distributor(X1-T1),the mixing index increases to 0.85(obviously higher than 0.46 for the mixer T1 without a distributor),meanwhile the corresponding power consumption is about 1/5 of that of T1 achieving the same mixing effect.It illustrates that the distributor can significantly improve the mixing of highly viscous fluids in the MRSM without the cost of large power consumption.These results would provide a guidance on the design and optimization of multistage rotor-stator mixers in industrial applications. 展开更多
关键词 Multistage rotor-stator mixer Computational fluid dynamics Mixing index Power consumption DISTRIBUTOR
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Characterization of the pairwise correlations in different quantum networks consisting of four-wave mixers and beamsplitters
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作者 祁健 忻俊 +1 位作者 王海龙 荆杰泰 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第7期153-160,共8页
We investigate the performances of the pairwise correlations(PCs) in different quantum networks consisting of fourwave mixers(FWMs) and beamsplitters(BSs). PCs with quantum correlation in different quantum netwo... We investigate the performances of the pairwise correlations(PCs) in different quantum networks consisting of fourwave mixers(FWMs) and beamsplitters(BSs). PCs with quantum correlation in different quantum networks can be verified by calculating the degree of relative intensity squeezing for any pair of all the output fields. More interestingly, the quantum correlation recovery and enhancement are present in the FWM+BS network and the repulsion effect phenomena(signal(idler)-frequency mode cannot be quantum correlated with the other two idler(signal)-frequency modes simultaneously)between the PCs with quantum correlation are predicted in the FWM + FWM and FWM + FWM + FWM networks. Our results presented here pave the way for the manipulation of the quantum correlation in quantum networks. 展开更多
关键词 pairwise correlation four-wave mixer degree of relative intensity squeezing quantum network
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Noise temperature distribution of superconducting hot electron bolometer mixers
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作者 Kang-Min Zhou Wei Miao +5 位作者 Yue Geng Yan Delorme Wen Zhang (任远) Kun Zhang Sheng-Cai Shi 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第5期41-46,共6页
We report on the investigation of optimal bias region of a wide-band superconducting hot electron bolometer(HEB)mixer in terms of noise temperature performance for multi-pixel heterodyne receiver application in the 5-... We report on the investigation of optimal bias region of a wide-band superconducting hot electron bolometer(HEB)mixer in terms of noise temperature performance for multi-pixel heterodyne receiver application in the 5-meter Dome A Terahertz Explorer(DATE5)telescope.By evaluating the double sideband(DSB)receiver noise temperature(Trec)across a wide frequency range from 0.2 THz to 1.34 THz and with a large number of bias points,a broad optimal bias region has been observed,illustrating a good bias applicability for multipixel application since the performance of the HEB mixer is uniquely determined by each bias point.The noise temperature of the HEB mixer has been analyzed by calibrating the noise contribution of all RF components,whose transmissions have been measured by a time-domain spectroscopy.The corrected noise temperature distribution shows a frequency independence relation.The dependence of the optimal bias region on the bath temperature of the HEB mixer has also been investigated,the bath temperature has limited effect on the lowest receiver noise temperature until 7 K,however the optimal bias region deteriorates obviously with increasing bath temperature. 展开更多
关键词 superconducting hot electron bolometer(HEB)mixer noise temperature distribution bath temperature dependence frequency dependence
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A 16-QAM 45-Gbps 7-m Wireless Link Using InP HEMT LNA and GaAs SBD Mixers at 220-GHz-Band
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作者 Yukun Li Yong Zhang +3 位作者 Chengkai Wu Jianhan Cui Huali Zhu Bo Yan 《China Communications》 SCIE CSCD 2021年第5期255-262,共8页
This paper presents a 220-GHz-band 7-m wireless link with a 45-Gbps transmission data rate by using 16 quadrature amplitude modulation(16-QAM).Super-heterodyne transceiver modules are developed for transmission and re... This paper presents a 220-GHz-band 7-m wireless link with a 45-Gbps transmission data rate by using 16 quadrature amplitude modulation(16-QAM).Super-heterodyne transceiver modules are developed for transmission and reception of the modulated signals,which consist of a Schottky barrier diodes(SBD)based sub-harmonic mixer(SHM),an InP HEMT low noise amplifier(LNA),a waveguide band-pass filter(BPF),and a 108-GHz local oscillator(LO)multiplier chain.The transmitter features a peak transmit power of 1.41 dBm,and the IF frequency varies from 5 GHz to 20 GHz.Besides,the receiver features a conversion gain of 9.3 dB in average and a noise temperature of 3052.8 K.The measured results indicate that the transceiver modules enable data transmission of a 45-Gbps 16-QAM signal with Signal-Noise-Ratio(SNR)from 11.59 dB to 15.36 dB in a 7-m line-of-sight channel. 展开更多
关键词 wireless link 16 quadrature amplitude modulation(16-QAM) super-heterodyne transceiver modules sub-harmonic mixer(SHM)
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Quantitative Evaluation of Mixing Characteristics of Static Mixers by Visualization Experiments
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作者 Noboru Mochizuki Aya Kaide Takashi Saeki 《Journal of Flow Control, Measurement & Visualization》 2018年第1期27-38,共12页
We propose a convenient way of evaluating the mixing performance of static mixers used for round pipe by conducting flow visualization experiments under the turbulent region and using water as the main stream. A fluor... We propose a convenient way of evaluating the mixing performance of static mixers used for round pipe by conducting flow visualization experiments under the turbulent region and using water as the main stream. A fluorescent pigment, glycerin, two carboxymethyl cellulose solutions, and rapeseed oil were each injected upstream of the mixer. Three static mixer conditions were tested: 1) no static mixer;2) a Kenics-type static mixer;and 3) a multi-stacked elements (MSE) static mixer. The mixing trend downstream of the mixer in each condition and with each injection fluid was monitored using a laser and high-speed video camera system to obtain cross-sectional images. We propose suitable indexes based on the images obtained for quantitative evaluations of the mixing characteristics of static mixers. 展开更多
关键词 Line MIXER Stacked ELEMENTS PIGMENT MIXING Performance VISUALIZATION EXPERIMENT
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Mixers of Ultra-High Gain from 5.0 to 18.0 GHz
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作者 Hsin-Chia Yang Jui-Ming Tsai +3 位作者 Cheng-Huang Tsao Mu-Chun Wang Sungching Chi Tsin-Yuan Chang 《Wireless Engineering and Technology》 2013年第1期1-4,共4页
Mixers in the communication system provide the possibility of encoding and decoding radio-frequency EM waves with signals through the help of local oscillators. A mixer with capability of high conversion gain, good is... Mixers in the communication system provide the possibility of encoding and decoding radio-frequency EM waves with signals through the help of local oscillators. A mixer with capability of high conversion gain, good isolation, and good linearity is comparably appreciated. Extensively wide ranges of frequencies, from 5.0 to 18.0 GHz, are to be examined addressing the promising functions of mixers in this study. A TSMC 0.18 μm CMOS model implanted in Agilent ADS is used for the circuit designs. Generated from Gilbert Cell Mixer, the modified circuits take advantage of extra active and passive devices to optimize the conversion gains. Characteristics of high conversion gain over 20 dB or even higher (as high as 29.842 dB at -40 mW RF power at working frequency 6 GHz) and low noise figures (NF) are shown. 展开更多
关键词 Gilbert Cell MIXER P1dB LINEARITY Noise FIGURE (NF) Conversion Gain Isolation
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CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer
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作者 Junhai Deng Shilin Lan +4 位作者 Juchang Wu Shenghua Du Weidong Liu Luchang Han Yefeng Zhou 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第6期173-188,共16页
Kenics static mixers(KSM)are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency,low power homogenization and easy continuous production.Resolving liquid droplet size and its d... Kenics static mixers(KSM)are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency,low power homogenization and easy continuous production.Resolving liquid droplet size and its distribution and thus revealing the dispersion characteristics are of great significance for structural optimization and process intensification in the KSM.In this work,a computational fluid dynamics-population balance model(CFD-PBM)coupled method is employed to systematically investigate the effects of operating conditions and structural parameters of KSM on droplet size and its distribution,to further reveal the liquid-liquid dispersion characteristics.Results indicate that higher Reynolds numbers or higher dispersed phase volume fractions increase energy dissipation,reducing Sauter mean diameter(SMD)of dispersed phase droplets and with a shift in droplet size distribution(DSD)towards smaller size.Smaller aspect ratios,greater blade twist and assembly angles amplify shear rate,leading to smaller droplet size and a narrower DSD in the smaller range.The degree of impact exerted by the aspect ratio is notably greater.Notably,mixing elements with different spin enhance shear and stretching efficiency.Compared to the same spin,SMD becomes 3.7-5.8 times smaller in the smaller size range with a significantly narrower distribution.Taking into account the pressure drop and efficiency in a comprehensive manner,optimized structural parameters for the mixing element encompass an aspect ratio of 1-1.5,a blade twist angle of 180°,an assembly angle of 90°,and interlaced assembly of adjacent elements with different spin.This work provides vital theoretical underpinning and future reference for enhancing KSM performance. 展开更多
关键词 CFD Population balance Liquid-liquid dispersion Kenics static mixer
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Terahertz high-sensitivity SIS mixer based on Nb–AlN–NbN hybrid superconducting tunnel junctions
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作者 刘博梁 刘冬 +8 位作者 姚明 金骏达 王争 李婧 史生才 Artem Chekushkin Michael Fominsky Lyudmila Filippenko Valery Koshelets 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期681-686,共6页
The terahertz band,a unique segment of the electromagnetic spectrum,is crucial for observing the cold,dark universe and plays a pivotal role in cutting-edge scientific research,including the study of cosmic environmen... The terahertz band,a unique segment of the electromagnetic spectrum,is crucial for observing the cold,dark universe and plays a pivotal role in cutting-edge scientific research,including the study of cosmic environments that support life and imaging black holes.High-sensitivity superconductor–insulator–superconductor(SIS)mixers are essential detectors for terahertz astronomical telescopes and interferometric arrays.Compared to the commonly used classical Nb/AlO_(x)/Nb superconducting tunnel junction,the Nb/AlN/NbN hybrid superconducting tunnel junction has a higher energy gap voltage and can achieve a higher critical current density.This makes it particularly promising for the development of ultra-wideband,high-sensitivity coherent detectors or mixers in various scientific research fields.In this paper,we present a superconducting SIS mixer based on Nb/AlN/NbN parallel-connected twin junctions(PCTJ),which has a bandwidth extending up to490 GHz–720 GHz.The best achieved double-sideband(DSB)noise temperature(sensitivity)is below three times the quantum noise level. 展开更多
关键词 SIS mixer TERAHERTZ gap voltage critical current density hybrid superconducting tunnel junction
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