Dynamic measurements of hydrate based gas separation in cooled silica gel

Mingjun Yang,Yongchen Song,Lanlan Jiang,Xiaojing Wang,Weiguo Liu,Yuechao Zhao,Yu Liu,Shanrong Wang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.1

Hydrate based gas separation is a promising method for carbon dioxide capture. The purpose of thisstudy is to analyze hydrates formation and dissociation characters when gas mixture flows throughcooled silica gel. The additives mixture (THF/SDS) was used to saturate the silica gel partly, and gasmixture (CO2/H2) was injected into it to form hydrates. Magnetic resonance imaging (MRI) images wereobtained using fast spin echo multi-slice pulse sequence. Hydrates saturations were calculatedquantitatively using MRI data. The experimental results showed that the optimal initial solutionsaturation was 34.2% in this investigation. The gas component was analyzed to assess the separationefficiency. For hydrates dissociation processes at 1 atmospheric pressure, CO2 concentrations increasedobviously. Half of the six cycles showed that more than 85.00 mol% CO2 contained in the capture gas, andthe lowest CO2 concentration was 64.83 mol%. Hydrate blockages appeared frequently, which restrictedthe contact of gas and solution and caused the incomplete transformations of residual solution tohydrates. It was a key restricted factor for hydrate based CO2 capture.

Hybrid medium model for conjugate heat transfer modeling in the core of sodium-cooled fast reactor

Wang, X.A.,Zhang, Dalin,Wang, Mingjun,Song, Ping,Wang, Shibao,Liang, Yu,Zhang, Yapei,Tian, Wenxi,Qiu, Suizheng,Su, G.H. Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.4

Core-wide temperature distribution in sodium-cooled fast reactor plays a key role in its decay heat removal process, however the prediction for temperature distribution is quite complex due to the conjugate heat transfer between the assembly flow and the inter-wrapper flow. Hybrid medium model has been proposed for conjugate heat transfer modeling in the core. The core is modeled with a Realistic modeled inter-wrapper flow and hybrid medium modeled assembly flow. To validate present model, simulations for a three-assembly model were performed with Realistic modeling, traditional porous medium model and hybrid medium model, respectively. The influences of Uniform/Non-Uniform power distribution among assemblies and the Peclet number within the assembly flow have been considered. Compared to traditional porous medium model, present model shows a better agreement with in Realistic modeling prediction of the temperature distribution and the radial heat transfer between the inter-wrapper flow and the assembly flow.

CFD simulation of flow and heat transfer characteristics in a 5×5 fuel rod bundles with spacer grids of advanced PWR

Wang Yingjie,Wang Mingjun,Ju Haoran,Zhao Minfu,Zhang Dalin,Tian Wenxi,Liu Tiancai,Qiu Suizheng,Su G.H. 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.7

High fidelity nuclear reactor fuel assembly simulation using CFD method is an effective way for the structure design and optimization. The validated models and user practice guidelines play critical roles in achieving reliable results in CFD simulations. In this paper, the international benchmark MATiS-H is studied carefully and the best user practice guideline is achieved for the rod bundles simulation. Then a 5 5 rod bundles model in the advanced pressurized water reactor (PWR) is established and the detailed three-dimensional thermal-hydraulic characteristics are investigated. The influence of spacer grids and mixing vanes on the flow and hear transfer in rod bundles is revealed. As the coolant flows through the spacer grids and mixing vanes in the rod bundles, the drastic lateral flow would be induced and the pressure drop increases significantly. In addition, the heat transfer is enhanced remarkably due to the strong mixing effects. The calculation results could provide meaningful guidelines for the design of advanced PWR fuel assembly

A Novel Algorithm for Green Citrus Detection based on the Reticulate Grayladder Feature

Mingjun Wang,Jun Zhou,Weiyan Shang,Rufu Hu,Xuefeng Wang,Liang Gong 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.10

Immature green citrus fruit detection using conventional color images is a challenging task due to fruit color similarity with the background, partial occlusion, varying illumination and shape irregularity. Therefore, most existing green fruits detection algorithms, which use color as the main discriminant feature, have a low recognition rate and a high rate of false positives. In this manuscript, we developed a novel Green Citrus fruit Detection algorithm based on the proposed Reticulate Grayladder Feature (GCDRGF), which contained 4 major steps: First, an 8-graylevel image was generated by the preprocessing steps of median filtering, histogram-based equalization and 8-graylevel discretization of the input raw image. Secondly, reticulate grayladders were obtained by a multidirectional scanning on the 8-graylevel image, and rule-based pseudo-grayladder removal strategies were used to remove false positives of target grayladders. Thirdly, grayladder clustering and fruit location fitting were used to generate candidate regions for target fruits. Finally, majority voting was performed to determine the results of candidate regions based on the analysis of apparent features and recticulate grayladders within candidate regions. The experimental results proved the effectiveness of the proposed reticulate grayladder feature and the corresponding detection algorithm with respect to various illuminant and imaging conditions. Compared with the existed eigenfruit algorithm, our algorithm has a higher rate of successful recognition and a lower rate of false positives, which helps to greatly improve the productivity of robotic operations.

Ab initio investigation into the structural, electronic and elastic properties of AlCu2TM (TM = Ti, Zr and Hf) ternary compounds

Mingjun Pang,Yongzhong Zhan,Haizhou Wang 한국물리학회 2012 Current Applied Physics Vol.12 No.3

The AleCueTM (TM = transition metal) alloy system has attracted great attention for both excellent glass-forming ability and its interesting physical properties. In this work, an investigation into the crystal,electrical and elastic properties of the AlCu2TM (TM = Ti, Zr, and Hf) compounds has been conducted by first-principles calculations based on density-functional theory. The fully relaxed structure parameters of the AlCu2TM compounds are in good agreement with previous experimental and other theoretical results. Besides, the cohesive energies of all the AlCu2TM compounds have been evaluated. The energy band and densities of state of these compounds are also obtained. According to the calculated single crystal elastic constants, all the compounds are mechanically stable. The polycrystalline bulk moduli,shear moduli, Young’s moduli and Poisson’s ratio have been deduced by using VoigteReusseHill (VRH)approximations. The calculated negative Cauchy pressure and ratio of bulk modulus to shear modulus indicated that the AlCu2TM compounds are ductile materials. The Debye temperatures of the AlCu2TM compounds decrease with increasing the TM (Ti, Zr, and Hf) atomic number.

Investigation on effect of surface properties on droplet impact cooling of cladding surfaces

Wang, Zefeng,Qu, Wenhai,Xiong, Jinbiao,Zhong, Mingjun,Yang, Yanhua Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.3

During transients or accidents, the reactor core is uncovered, and droplets entrained above the quench front collides with the uncovered fuel rod surface. Droplet impact cooling can reduce the peak cladding temperature. Besides zirconium-based cladding, versatile accidental tolerant fuel (ATF) claddings, including FeCrAl, have been proposed to increase the accident coping time. In order to investigate the effect of surface properties on droplet impact cooling of cladding surfaces, the droplet impact phenomena are photographed on the FeCrAl and zircaloy-4 (Zr-4) surfaces under different conditions. On the oxidized FeCrAl surface, the Leidenfrost phenomenon is not observed even when the surface temperature is as high as 550 ℃ with We > 30. Comparison of the impact behaviors observed on different materials shows that nucleate and transition boiling is more intensive on surfaces with larger thermal conductivity. The Leidenfrost point temperature (LPT) decreases with the solid thermal effusivity (${\sqrt{k{\rho}C_p}}$). However, the CHF temperature is relatively insensitive to the surface oxidation and Weber number. Droplet spreading diameter is analyzed quantitatively in the film boiling stage. Based on the energy balance a correlation is proposed for droplet maximum spreading factor. A mechanistic model is also developed for the LPT based on homogeneous nucleation theory.

Short-Term Wind Speed Forecast Based on Least Squares Support Vector Machine

Wang, Yanling,Zhou, Xing,Liang, Likai,Zhang, Mingjun,Zhang, Qiang,Niu, Zhiqiang Korea Information Processing Society 2018 Journal of information processing systems Vol.14 No.6

There are many factors that affect the wind speed. In addition, the randomness of wind speed also leads to low prediction accuracy for wind speed. According to this situation, this paper constructs the short-time forecasting model based on the least squares support vector machines (LSSVM) to forecast the wind speed. The basis of the model used in this paper is support vector regression (SVR), which is used to calculate the regression relationships between the historical data and forecasting data of wind speed. In order to improve the forecast precision, historical data is clustered by cluster analysis so that the historical data whose changing trend is similar with the forecasting data can be filtered out. The filtered historical data is used as the training samples for SVR and the parameters would be optimized by particle swarm optimization (PSO). The forecasting model is tested by actual data and the forecast precision is more accurate than the industry standards. The results prove the feasibility and reliability of the model.

Airbag Damping of the Hollow Fiber Composite with Different Porosity in the Fiber Wall

Mingjun Li,Guoqun Zhou,Yongwen Xu,Guifang Wang 한국섬유공학회 2019 Fibers and polymers Vol.20 No.2

The inner cavity of the hollow fiber with porosity in its fiber wall constitutes a damping airbag with slow passage of gas. The magnitude of the damping value of the airbag and its damping influencing factors need to be researched, which adds the nonlinear airbag damping to the damping of the raw materials and increases the total damping loss factor of the structure. In this paper, the hollow fiber damping materials with different hollow inside diameters, different fiber wall thicknesses, different wall porosity and different wall pore structure were prepared by adjusting and controlling the technological parameters of the hollow fiber spinning and the formula of spinning casting solution. Meanwhile, we have a comprehensive study on the relationship between the factors and performances. It was found and confirmed that the size of the airbag, the wall pore structure, the wall porosity and the wall thickness of the airbag were the most crucial parameters, which can affect the additional damping of the airbag in the hollow fiber. And the controlling method of the four key parameters was also obtained. Finally, the mechanism and effect of hollow fiber airbag damping was proved.

Preparation and characterization of Ag2O/SWNTs photocatalysts and its photodegradation on tetracycline

Huiqin Wang,Pengwei Huo,Jinze Li,Mingjun Zhou,Qingfeng Guan,Ziyang Lu,Yongsheng Yan 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.30 No.-

The Ag2O/SWNTs photocatalysts were prepared by precipitated method, the photocatalysts werecharacterized by XRD, SEM, TEM, EDS, BET, UV–vis DRS, XPS, PL and Raman. The photocatalytic activitieswere evaluated by degradation of tetracycline. The results showed that the composited photocatalystswere successfully prepared, the responded light was enhanced with increasing the supported dosage ofAg2O, and the photocatalytic activity was also improved. The enhanced photocatalytic activity wasattributed to the synergy effect of SWNTs and Ag2O, the recycled degradation of tetracycline exhibitedstability of Ag2O/SWNTs composited photocatalysts. Finally, the possible mechanism for transferredprocesses of photoelectrons and photoholes were proposed.

High photocatalytic degradation of tetracycline under visible light with Ag/AgCl/activated carbon composite plasmonic photocatalyst

Huiqin Wang,Xiaoqing Yang,Jinzhao Zi,Mingjun Zhou,Zhefei Ye,Jinze Li,Qingfeng Guan,Peng Lv,Pengwei Huo,Yongsheng Yan 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.35 No.-

Ag/AgCl/activated carbon (AC) plasmonic photocatalysts were prepared by precipitation and photoreduc-tion method. The as-prepared plasmonic photocatalysts were characterized by XRD, SEM, BET, EDS, UV–visDRS, XPS and PL. The results show the composite photocatalysts are successfully obtained and obviouslyexhibit surface plasmon resonance and effectively enhance the separation of h+/e . The photocatalyticdegradation rate of tetracycline (TC) could reach 97.3% in 60 min under visible light irradiation and cycledexperiments show stably photocatalytic activities. The active species analysis displays holes andsuperoxide radicals are the main reactive species. Photocatalytic kinetic indicates that the degradationprocesses obey pseudo first order kinetic equation.