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- 저자 : Junhao Ma (검색결과 4 건)
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Cascade hydrogenation of n-C16 to produce jet fuel over tandem catalysts of modified ZSM-22
Yi Li,Junhao Sun,Jie Wei,Chao Mu,Yujun Zhao,Shengping Wang,Xinbin Ma 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.111 No.-
ZSM-22 with one-dimensional straight channels and suitable acid properties is widely applied in theselective hydrocracking of long-chain alkanes to produce middle distillate. In this work, the tandem catalystswith two kinds of modified ZSM-22 were employed in series to optimize the distribution of theproduct in the hydrotreatment of n-C16 to produce jet fuel. The yield of linear alkanes with high carbonnumbers was enhanced over the upstream catalyst bed of Pt/L-HZSM-22 with shielded external acid siteswhile the isomerization with less further cracking occurred over the downstream catalyst bed of Pt/Me-HZSM-22 with introduced mesopores. The tandem catalysts can combine the ability of Pt/L-HZSM-22 toproduce heavy n-alkanes and the stronger isomerization performance of Pt/Me-HZSM-22. The highestyield of jet fuel (23 wt.%) can be obtained over the tandem catalysts instead of any individual catalyst. The strategy of the tandem zeolite has been initially verified and proposed to broaden the investigationperspectives of the oil refinery.
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Coupling effects of vortex-induced vibration for a square cylinder at various angles of attack
Deqian Zheng,Wenyong Ma,Xiaobin Zhang,Wei Chen,Junhao Wu 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.34 No.5
Vortex-induced vibration (VIV) is a significant concern when designing slender structures with square cross sections. VIV strongly depends on structural dynamics and flow states, which depend on the conditions of the approaching flow and shape of a structure. Therefore, the effects of the angle of attack on the coupling effects of VIV for a square cylinder are expected to be significant in practice. In this study, the aerodynamic forces for a fixed and elastically mounted square cylinder were measured using wind pressure tests. Aerodynamic forces on the stationary cylinder are firstly discussed by comparisons of variation of statistical aerodynamic force and wind pressure coefficient with wind angle of attack. The coupling effect between the aerodynamic forces and the motion of the oscillating square cylinder by VIV is subsequently investigated in detail at typical wind angels of attack with occurrence of three typical flow regimes, i.e., leading-edge separation, separation bubble (reattachment), and attached flow. The coupling effect are illustrated by discussing the onset of VIV, characteristics of aerodynamic forces during VIV, and interaction between motion and aerodynamic forces. The results demonstrate that flow states can be classified based on final separation points or the occurrence of reattachment. These states significantly influence coupling effects of the oscillating cylinder. Vibration enhances vortex shedding, which creates strong fluctuations in aerodynamic forces. However, differences in the lock-in range, aerodynamic force, and interaction process for angles of attack smaller and larger than the critical angle of attack revealed noteworthy characteristics in the VIV of a square cylinder.
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Modeling the Diffusion-Driven Growth of a Pre-Existing Gas Bubble
Anil Kunwar,Haitao Ma,Junhao Sun,Shuang Li,Jiahui Liu 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.5
Finite element method is utilized to solve the diffusion equation and model the diffusion driven growth of a pre-existing spherical gas bubble in molten tin at the solder/substrate interface for reflow time of 120 s and temperature of 250 °C. The gibbs free energy change required for determining the equilibrium concentration at liquid solder/gas bubble boundary was calculated using the thermodynamic polynomial coefficients. The rate of change of radius, as function of concentration flux, is calculated using the lagrangian mesh update methodology. With an initial diameter of 20 μm, the bubble growth is calculated as a function of contact angle. When the wetting angle is varied from a value of 30° to 135°, the numerical calculation has yielded the final sizes for the bubble to change from 62.87 μm to 82.8 μm respectively. The effect of wetting transition in the growth of bubble was studied by the in-situ observation of bubble dynamics through synchrotron radiation imaging technique. The scanning electron microscopy images of the morphologies of intermetallic compounds influenced by growing bubble in Sn/Cu solder joint and bubble pictures obtained through synchrotron radiation are utilized to get the experimental size of the bubble. The mean experimental bubble diameter has been obtained as 76.39 μm. The growing bubble inhibits the growth of intermetallic compound at its vicinity and thereby reduces the strength of solder joints.
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Shiqi Liu,Xiangting Hou,Chengze Yu,Xiangrui Pan,Junhao Ma,Guocheng Liu,Chengzhi Zhou,Yanjun Xin,Qinghua Yan 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-
Among the bromine flame retardants, tetrabromobisphenol A (TBBPA) is a highly effective flame retardantthat can be used as both reactive and additive. However, the synthesis reaction of TBBPA has alow conversion rate and many brominated phenolic organics. Therefore, there is an urgent need toremove brominated organic pollutants produced in the process of producing flame retardants to reducethe harm to the environment and human beings and to reduce production costs. In this study, an efficientprocess was developed to treat the wastewater and waste residue generated in TBBPA production process,realizing its harmless and resource utilization. In the resource utilization system, through the ingeniousdesign of solution mixing, precipitation separation, three-effect evaporation and concentration,valuable substances were extracted to realize the recovery and reuse of wastewater. In the harmless utilizationprocess of hazardous waste residue, through high-temperature pyrolysis at 500 C for 2 h afteroptimization with hypoxia-hyperoxia atmosphere modulation, it can avoid the production of dioxinsand carbon black, effectively remove the organic impurities, realize the harmlessness and obtain highqualitysodium sulfate. This paper aims to propose a simple, efficient and feasible utilization system,including the three major technological processes of TBBPA production, integrated wastewater treatmentand optimized the harmless treatment of waste residue to obtain sodium sulfate, so as to realize TBBPAgreen production. Compared with the traditional TBBPA synthesis system, wastewater and waste residuetreatment processes, the TBBPA quality is increased by 2 % and the economic cost is reduced by 10 %,which is of great significance to the development of the industry.
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