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Table of Content
31 March 2019, Volume 70 Issue S1
    Reviews and monographs
    Progress in research and application of microwave in chemical process
    Zhaowen ZENG, Cheng ZHENG, Taoyan MAO, Yuan WEI, Runhui XIAO, Siyu PENG
    2019, 70(S1):  1-14.  doi:10.11949/j.issn.0438-1157.20181484
    Abstract ( 151 )   HTML ( 9)   PDF (1595KB) ( 94 )  
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    Compared with the conventional heating method, microwave-assisted organic syntheses takes the advantages of speeding up the reaction rate, increasing the product yields and changing the selectivity. These phenomena, which cannot be reproduced by conventional heating method, are named microwave nonthermal effects by researchers. But debates about whether nonthermal effects exist or not have continued until now. Up to now, the mechanism of microwave-promoting synthetic reactions is unclear. In this paper, the application progress of microwave technology in organic synthesis and chemical separation process was summarized. The research progress of microwave thermal effect and non-thermal effect in recent years was reviewed. The case analysis and theoretical viewpoint of microwave effect were expounded, and the development of microwave-assisted industrialization was analyzed and prospected.

    Research progress of microwave assisted biodiesel production
    Hui SHANG, Yu DING, Wenhui ZHANG
    2019, 70(S1):  15-22.  doi:10.11949/j.issn.0438-1157.20181400
    Abstract ( 145 )   HTML ( 13)   PDF (547KB) ( 106 )  
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    Due to the characteristics of selectivity, instantaneity and volumetric heating, microwaves can increase the reaction rate by increasing the average energy of organic reaction molecules and increasing their collision frequency. Microwave assisted preparation of biodiesel through catalytic transesterification has attracted more and more attention from the scholars. The application of microwave in the preparation of biodiesel has significant advantages compared to the traditional heating method the reaction time is obviously shortened and the products compositions are changed as well. This paper reviews the research progress of biodiesel preparation through acidic/basic catalytic transesterification using microwave heating, and the future trend is also prospected.

    Thermodynamics
    Effect of microwave field on hydrogen bonds in glycerol aqueous solution system
    Hui SHANG, Lu LIU, Hanmo WANG, Wenhui ZHANG
    2019, 70(S1):  23-27.  doi:10.11949/j.issn.0438-1157.20181413
    Abstract ( 108 )   HTML ( 3)   PDF (757KB) ( 46 )  
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    Molecular dynamics simulation was employed to investigate the effect of the microwave on the hydrogen bond in the glycerol aqueous solution with different concentration. It was observed that at higher glycerol concentration, glycerol molecules existed in large clusters, whilst water in small clusters or at free state. The clusters of glycerol molecules changed from large to small and became more ordered under the electric field. As the electric field intensity further increased, the overall structure of glycerol molecule did not change obviously, the hydrogen bonds at the edge of glycerol clusters were found broken. For water molecules, smaller clusters under the effect of electric field were broken and disappeared, so water molecules were arranged neatly in the direction of electric field. As the electric field intensity continues to increase, the structure of water remained unchanged, and the hydrogen bonds of water changed to a free state. Therefore at higher glycerol concentration, the hydrogen bonds of water decreased, and those of glycerol first increased and then decreased slightly; at lower glycerol concentration, hydrogen bonds of water increased first and then decreased slightly, while those of glycerol decreased.

    Fluid dynamics and transport phenomena
    Low frequency electromagnetic parameters and absorbing heat generation properties of carbon nanotubes
    Zhe LI, Wenlong WANG, Meng ZHANG, Jing SUN, Yanpeng MAO, Xiqiang ZHAO, Zhanlong SONG
    2019, 70(S1):  28-34.  doi:10.11949/j.issn.0438-1157.20181402
    Abstract ( 70 )   HTML ( 4)   PDF (699KB) ( 40 )  
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    The microwave thermal utilization technology has promoted the application study of microwave absorbing materials. Carbon nanotubes (CNTs), small in density, large in surface area and with quantum size effect,are new strong absorbing materials in recent years. This article investigated the complex permittivity and complex permeability of CNTs with the change of carbon nanotubes content. On basis of it, absorbing heat generation properties of carbon nanotube were explored under microwave radiation. The coaxial transmission method is suitable for the measurement of small samples which is accurate, so choosing this method to explore its electromagnetic parameters. The results show that both electrical and magnetic losses are exits in CNTs when losing microwave energy. From study of heat generation properties, it is concluded that CNTs is a material whose microwave absorbing ability is strong.

    Chaotic analysis of pressure fluctuation and identification of flow regime in chlor-alkali electrolyzer
    Li ZHANG, Gang YOU, Xiaofeng QIAO, Guangwen XU, Guozhen LIU, Yunyi LIU
    2019, 70(S1):  35-44.  doi:10.11949/j.issn.0438-1157.20180914
    Abstract ( 75 )   HTML ( 5)   PDF (1893KB) ( 44 )  
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    In order to clarify the pressure fluctuation characteristics and flow patterns of the gas- liquid two-phase flow in the chlor-alkali electrolyzer, the pressure signals at the upper opening of the recirculation plate in the anode chamber of a cold-model electrolyzer were analyzed by using chaos method. The flow patterns were identified by the Kolmogorov entropy descending method and the pictures taken by a high-speed camera. The flow pattern maps were drawn. The flow patterns under different current densities were determined. The results show that, the attractors of pressure signal of electrolyzer have fractional dimension. The values of Lyapunov exponent are greater than 0 when the current density exceeds 6 kA·m-2. These results demonstrate the gas-liquid two-phase flow in the electrolyzer has chaotic characteristics. For the position of the upper opening of the circulation plate and the lower section of the electrolyzer, the fully developed section of the jet flow and the isolated bubble flow appear when the current density is less than 5 kA·m-2. The transition section of the jet flow and combined bubble flow appear when the current density is 5-8 kA·m-2. The initial section of the jet flow and combined bubble flow appear when the current density is greater than 8 kA·m-2.

    Experimental study on condensation of FC-72 in narrow rectangular channel with ellipse-shape pin fins in microgravity
    Leigang ZHANG, Bo XU, Juan SHI, Zhenqian CHEN
    2019, 70(S1):  45-53.  doi:10.11949/j.issn.0438-1157.20190025
    Abstract ( 83 )   HTML ( 1)   PDF (970KB) ( 29 )  
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    The condensation heat transfer of FC-72 in a narrow rectangular channel with four kinds of elliptical pin-fin surfaces and a flat surface under microgravity condition was studied by visualization experiments. The effects of microgravity on condensate distribution, steam-liquid interface, condensation substrate temperature, inlet steam temperature and heat flux were analyzed. The results showed that the steam-liquid interface in the narrow rectangular channel was unstable, fluctuated and climbed along the lateral wall in microgravity. No obvious changes were observed in liquid film on the condensing surface after the release of drop cabin. For unsteady state, the condensation substrate temperature increased slightly, and there was a certain delay. After the release of drop cabin, the change of flow pattern in steam generator coil improved the heating efficiency, which resulted in a sharp rise in inlet steam temperature. For pulsating state, the change of substrate temperature was similar to that of unsteady state, but there was no obvious change in inlet steam temperature. For quasi-steady state, the temperature at some temperature measuring points jumped a little bit, but the inlet steam temperature had no obvious change. Furthermore, the heat flux decreased sharply in microgravity, falling by 18.8%.

    Experimental study on evolution of waterfilm height during static flash of pure water
    Huihui WANG, Dan ZHANG, Qingzhong YANG, Zhaocheng NIU
    2019, 70(S1):  54-60.  doi:10.11949/j.issn.0438-1157.20180991
    Abstract ( 72 )   HTML ( 2)   PDF (1236KB) ( 21 )  
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    Experimental study on evolution of waterfilm height during static flash of pure water was carried out with superheat varying between 7.0 K and 32.5 K, orifice diameter at 5, 10, 20 mm, and flash speed between 0.004 s-1 and 0.073 s-1. Results indicated that the maximum expansion rate of waterfilm increased with rising superheat or orifice diameter. At given orifice diameter, the flash speed decreased with rising superheat, however, the maximum expansion rate of waterfilm increased with it. At given superheat, both flash speed and the maximum expansion rate increased with increasing orifice diameter. At last, an experimental correlation was set up between maximum expansion rate and superheat, flash speed. The calculated results matched well with experimental data. These results provided a technical support for the miniaturization, compactness and finely control of industrial flash system.

    Two-phase mass transfer of multi-benzene gemini quaternary ammonium salt in oil-water
    Guanghua ZHANG, Qiuchen DONG, Jing LIU
    2019, 70(S1):  61-68.  doi:10.11949/j.issn.0438-1157.20181401
    Abstract ( 45 )   HTML ( 2)   PDF (644KB) ( 17 )  
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    Distribution coefficients of two kinds of cationic gemini quaternary ammonium salt corrosion inhibitors (bi-PDTBP and PDTBP) between water and oil were measured by ultraviolet spectrophotometry, from which thermodynamic parameters were calculated. Effects of temperature, oil-water ratio, salt content, inhibitor concentration and time on the mass transfer between water and oil were systematically investigated. Finally, the corrosion inhibition performance of two corrosion inhibitors for Q235 steel in 1 mol/L hydrochloric acid was studied by weight loss experiments. Results showed that temperature and inhibitor concentration can promote the mass transfer of corrosion inhibitors between oil-water two phases, while oil-water ratio and salt concentration can hinder the mass transfer of corrosion inhibitors between oil-water two phases. The mass transfer process is spontaneous and endothermic reaction accompanied by an increase in entropy. In addition, as the concentration of two inhibitors increases, the corrosion inhibition efficiency increases gradually, and bi-PDTBP showed greater corrosion inhibition effect than PDTBP at high temperature.

    Study on heat and mass transfer characteristics outside flat tube for evaporative condensers
    Siyu SHAN, Hongbo TAN
    2019, 70(S1):  69-78.  doi:10.11949/j.issn.0438-1157.20190033
    Abstract ( 77 )   HTML ( 6)   PDF (1108KB) ( 50 )  
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    Enhancement of the heat and mass transfer outside the tube of evaporative condensers can effectively reduce the energy consumption in a refrigeration system. The improving characteristics of heat and mass transfer outside a flat tube for evaporative condensers were investigated. Numerical simulation of the heat and mass transfer on the flat tube was carried out in Fluent using user define functions and component transport models. The heat transfer performance of a circular tube with the same perimeter was compared with that of the flat tube. The thickness and velocity of the liquid film outside the tube, the temperature distribution and the variation of moisture content outside the tube are studied, and the average heat transfer coefficients of the flat tube and the circular tube are compared. The results show that the average heat transfer coefficient of the flat tube is 9.04% higher than that of the circular tube. In addition, the influence of wind speed and spray density on the heat transfer of flat tube evaporative condenser is calculated. The wind speed varies from 1.5 m·s-1 to 3 m·s-1 and the spray density varies from 0.15 kg·m-1·s-1 to 0.3 kg·m-1·s-1. The results show that the average heat transfer coefficient increases by 5.68% and 30.26% respectively. Investigating the heat and mass transfer characteristics outside a flat tube for evaporative condensers provides theoretical guidance for the application of the flat tube in evaporative condensers.

    Experimental and numerical study of cooling characteristics of foam nickel plate
    Yaxiao TIAN, Naiyong WANG, Changxing LI, Wenjing DU
    2019, 70(S1):  79-85.  doi:10.11949/j.issn.0438-1157.20180888
    Abstract ( 66 )   HTML ( 3)   PDF (679KB) ( 23 )  
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    In this paper, the cooling characteristics of foam nickel plate in the cooling section of the production line are studied by means of experiment and numerical analyses. Experimental results show that during the normal operation progress, the temperature of the entire foam nickel plate remains basically unchanged. The maximum temperature gradients are located at two positions, one is the entrance of the reducing gas and the other is in the first half of the high temperature water cooling section. If changing the movement velocity of the nickel plate, the first temperature gradient becomes larger together with the larger movement velocity of the nickel plate and the second temperature gradient decreases with the increase of movement velocity, and the corresponding positions are also changed. If changing the temperature of the high temperature water, the higher the water temperature, the smaller the temperature gradient in the second place, and the other temperature distribution is less affected.

    Numerical simulation of foam metal copper/paraffin phase change thermal storage process
    Hua CHEN, Xiuli LIU, Yaxing YANG, Liqiong ZHONG, Lei WANG, Na GAO
    2019, 70(S1):  86-92.  doi:10.11949/j.issn.0438-1157.20181268
    Abstract ( 69 )   HTML ( 6)   PDF (3321KB) ( 45 )  
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    The uniformity and stability of the paraffin temperature distribution in the phase change heat storage box with the addition of foam copper into the pure paraffin were predicted by Fluent software. The simulated results showed that the addition of foam copper greatly improved the heat recovery performance of paraffin and shortened paraffin phase transition time. Moreover, after adding foam copper, the paraffin inside temperature difference decreased significantly, the temperature distribution became more uniform, and top overheating and bottom un-melting caused by nature convection were effectively alleviated. The average error between the simulated results and test data were within 15.7%, which was in good agreement with the measured values.

    Simulation research of microwave heating efficiency for beamed energy thruster
    Hao YANG, Eryan YAN
    2019, 70(S1):  93-98.  doi:10.11949/j.issn.0438-1157.20181431
    Abstract ( 84 )   HTML ( 1)   PDF (920KB) ( 29 )  
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    Microwave beamed energy thruster is a kind of delivery tool using ground microwave beams to provide the energy to launch to the Earth 1st orbit from ground. The energy conversion is different with conventional microwave heating. In order to study the energy efficiency, the report gives a simple energy receiving module of thermal exchange system to simulate conversion process. Millimeter wave heating efficiency as well as maximum temperature have been analysised with the module. Further more, three fabric of exchange system was designed for 2-D simulation to explore the influence of structure. Genetic algorithm was used to optimize the parameters affecting the performance. Simulation results show that thermal exchange system performance follow with material permittivity damping which expected to be moderate. The maximum energy efficiency is over 30%, and the stabilization efficiency is around 23%.

    Catalysis, kinetics and reactors
    Catalysis effects of K2CO3 for gasification of semi-coke
    Fanrui MENG, Boyang LI, Xianchun LI, Shuang QIU
    2019, 70(S1):  99-109.  doi:10.11949/j.issn.0438-1157.20181224
    Abstract ( 62 )   HTML ( 5)   PDF (1870KB) ( 39 )  
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    Steam gasification of potassium-loaded semi-coke has been carried out with a fixed-bed laboratory gasifier at atmospheric pressure. With the K2CO3 loading increased the micropore area decreased. At a loading of 5% (mass), the K2CO3 mainly plays the role of filling pores. Above the loading of 10% (mass), the accumulation of catalyst will lead to more pores on the surface and interior of the particles. Increasing the gasification temperature could increase the carbon conversion rate, but above 750℃ the carbon conversion rate increased indistinctively. The loading values above which the effect was negligible were 10% (mass). High concentration of C(O) on the surface of particles and in open pores has a higher desorption rate and led to the generation rate of CO increase. Under non-catalytic conditions, CO/CO2 decreased as gasification time increasing, while H2/(2CO2+CO) increased first and then decreased. Under catalytic conditions, H2/(2CO2+CO) was stable at 1.5-1.7. The active components, such as K2Ca(CO3)2, K2O, and KO2, appeared in the catalyst semi-coke samples and increased with the catalyst loading increasing. Catalyst deactivation phenomenon was aggravated due to the loading increasing, but it was not completely inactivation under the condition of gasification 1 h at 750℃.

    One-pot synthesis of 2-amino-4-aryl-3-cyano-4H-benzochromene derivatives catalyzed by K2CO3 under microwave irradiation
    Yucai ZENG, Xiaoling LIU, Qifeng LIANG, Jianquan LYU
    2019, 70(S1):  110-114.  doi:10.11949/j.issn.0438-1157.20181418
    Abstract ( 100 )   HTML ( 4)   PDF (420KB) ( 27 )  
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    A series of 2-amino-4-aryl-3-cyano-4H-benzo[h]chromene or benzo[h]chromene derivatives were synthesized by a three-component one-pot reaction of aromatic aldehydes, malononitrile and α-naphthol(or β-naphthol) with K2CO3 as catalyst in anhydrous ethanol solvent under microwave irradiation. With benzaldehyde, malononitrile and α-naphthol as template reaction, the reaction conditions were optimized by single factor experiments. The results showed that 2-amino-4-aryl-3-cyano-4H-benzo[h]chromene(4a) was obtained 83.6% yield with the condition of each reactant 10 mmol, K2CO3 1 mmol and anhydrous ethanol 15 ml as solvent, using microwave power 500 W, reflux reaction 5 min at 80℃. Under the best of the above conditions,using substituted benzaldehyde to replace benzaldehyde, 4H-benzo[h]chromene derivatives(4) were obtained 65.8%~89.4% yield. Using β-naphthol to replace α-naphthol, 4H-benzo[f]chromene derivatives(6) were obtained 67.5%~82.9% yield. The structures of these compound were characterized by m.p. and IR.

    Separation engineering
    Microwave extraction of cardiovascular Chinese medicine formula warming heart
    Dantong LIU, Cheng ZHENG, Taoyan MAO
    2019, 70(S1):  115-123.  doi:10.11949/j.issn.0438-1157.20181392
    Abstract ( 72 )   HTML ( 1)   PDF (2799KB) ( 24 )  
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    Related researches show that traditional extraction methods, like decoction, are not suitable for extracting components with low thermal stability and the extraction rates are not high. At the same time, the current researches focus on the extraction of single herbs. Thus, in this paper, the microwave extraction technique was used to extract the active components in the warm-heart, a traditional Chinese medicine compound. The HPLC method was used to analyze the content of active ingredients in the extract. The factors influencing the extraction process, which is microwave power, extraction time and the number of times of extraction respectively, were investigated by single factor experiment. In addition, the cell wall breaking condition was analyzed by SEM to understand its microwave extraction mechanism. The experimental results showed that the optimal extraction conditions of microwave extraction active components were: microwave power 1200 W, extraction time 40 min, extraction times 1. Compared with the traditional heating extraction method, the microwave-assisted extraction technology could significantly shorten the extraction time and achieve energy saving and high efficiency. That was because microwave radiation could penetrate the inside of Chinese herbal medicines to break the cell wall and extract the effective formation of Chinese herbal medicines more efficiently.

    Resveratrol and polydatin by microwave-ultrasound extraction and determination by HPLC
    Mixia MA, Ning QIN, Qing MIN, Wenxiang HU
    2019, 70(S1):  124-129.  doi:10.11949/j.issn.0438-1157.20181483
    Abstract ( 74 )   HTML ( 2)   PDF (438KB) ( 35 )  
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    Objective to establish a method for the determination of resveratrol and polydatin in peanut bud and grape pip extract. High performance liquid chromatography (HPLC) was used. The chromatographic column was Di Ma C18, the mobile phase was acetonitrile water solution, gradient elution, flow rate 1 ml/min, column temperature 30℃, 306 nm and 20 μl. The linear range of resveratol showed good linear relationship 0.343-15.15×103μg /ml, R2 = 0.9967. The linear range of polydatin showed good linear relationship 110.712-1774.23×103 μg/ml, R2 = 0.9993. The method is rapid, simple and reproducible, and is suitable for quantitative analysis of resveratrol in peanut sprouts and grape seeds.

    Formation of framework supported pore for PVA/ZnO composite and Pb(Ⅱ) adsorption
    Sheng XU, Lingli LIU, Meng CAO, Shangxi ZHANG, Xin DAI, Yang LIU, Zhenxi WANG
    2019, 70(S1):  130-140.  doi:10.11949/j.issn.0438-1157.20181339
    Abstract ( 53 )   HTML ( 5)   PDF (2430KB) ( 43 )  
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    PVA/tetra-ZnO composite was prepared by in-situ chemical crosslinking reaction which was used as the absorbent of Pb(II) in waste water. The FTIR and TGA results indicated the successful grafting of APTES on the tetra-ZnO particles surface and the tetra-ZnO particles dispersed uniformly after modification. A special “framework supported” structure was formed around the pore-channel wall of PVA/tetra-ZnO composite due to the interlocking characteristic of the tetra-ZnO particle s four whisker arms and which was beneficial for the diffusion and adsorption of heavy metal ions solution. The Pb(II) adsorption capacity reached to the maximum at 7% tetra-ZnO content, and the adsorption effect was most significant at pH 4.0. Contrary to the distribution of pore size, the absorbed Pb(II) on PVA/tetra-ZnO composite was graded distribution from the out to inside with a gradual decease trend. The Langmuir model was better fitted the Pb(II) adsorption isotherm process which revealed the homogeneous monolayer adsorption mechanism. The adsorption kinetics indicated the stepwise adsorption process due to the perfect fitting degree of pseudo-first-order model as well the pseudo-first-order model. The intraparticle diffusion kinetics model indicated that the chemical adsorption and intraparticle diffusion played the important role during the whole adsorption process. Besides, the stress stability and thermo stability of PVA/tetra-ZnO composites were improved than neat PVA.

    Process system engineering
    Networked grading performance assessment method of chemical process based on Ms-LWPLS
    Chenxin CAO, Yupeng DU, Xin WANG, Zhenlei WANG
    2019, 70(S1):  141-149.  doi:10.11949/j.issn.0438-1157.20181369
    Abstract ( 64 )   HTML ( 4)   PDF (601KB) ( 42 )  
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    A networked performance assessment method based on multi-space locally weighted projection to latent structures (Ms-LWPLS) is proposed to solve the nonlinear relationship between input and output data of chemical process. This method divides the historical training datasets into different sets of performance grades, extracting the process changes of different performance grade of training datasets by Ms-LWPLS method. This method obtains the latent structures accurately by matching the training datasets and performance grade labels through the non-linear networked structure. The“off-line modeling”is achieved by the trained neural network. With the model obtained, the sliding window is used as the assessment unit, working as the input data into the trained neural network model. The current performance grade is identified according to the network output and the transition performance coefficient is constructed. The steady-state performance grades and the transition performance grades are recognized and distinguished. Finally, the method is applied to the online performance assessment of ethylene cracking process, which shows the effectiveness and accuracy of the performance assessment method proposed.

    Soft sensor of wet ball mill load parameters based on transfer variational autoencoder - label mapping
    Enwei ZHI, Fei YAN, Mifeng REN, Gaowei YAN
    2019, 70(S1):  150-157.  doi:10.11949/j.issn.0438-1157.20181069
    Abstract ( 94 )   HTML ( 4)   PDF (760KB) ( 59 )  
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    When the working condition of wet ball mill is changed, the distributions of real time data and modeling data are inconsistent, and the i.i.d assumption of traditional soft sensor method would not be satisfied, which leads to the inaccuracy of soft sensor model and the deterioration of the system performance. Therefore, by introducing the transfer learning method, a soft sensor model based on transfer variational autoencoder - label mapping strategy is proposed to achieve the precise measurement of wet ball mill load parameters under multiple working conditions. Firstly, the parameters of hidden variables distribution obtained by encode with target domain data are transferred to fit corresponding hidden variable of source domain data. For then, acquiring transfer data by decoding. Moreover, the similarity measure is used to select similar samples to construct the label mapping model, and the mapped labels are obtained. Then the final soft sensor model is constructed according to the transfer data and mapped labels. The experimental results show that the proposed soft sensor method is significantly better than the existing method, and the proposed method is suitable for soft sensor modeling under the situation of multi working condition.

    A grid reconstruction strategy based on pseudo Wigner-Ville analysis for dynamic optimization problem
    Weifeng XU, Aipeng JIANG, Haokun WANG, Enhui JIANG, Qiang DING, Hanhan GAO
    2019, 70(S1):  158-167.  doi:10.11949/j.issn.0438-1157.20180805
    Abstract ( 56 )   HTML ( 1)   PDF (709KB) ( 23 )  
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    In order to solve the contradiction between approximation accuracy and computation time of control vector parameterization (CVP) method, a control vector parameterization method based on pseudo Wigner-Ville time-frequency analysis is proposed. The method first gives a small number of meshes for the first optimization iteration, and quickly obtains the approximate trajectory of the control variables. Then, through the pseudo Wigner-Ville analysis, the influence of the instantaneous frequency change of the mesh nodes on the performance index is obtained, and the original mesh nodes are reconstructed based on above analysis, including the elimination and refinement of the time nodes. And then combined with the variable time node CVP method, the corresponding time nodes with the maximum instantaneous frequency are used as parameters, which are optimized together with the control variables to find accurate time switching points. Three classical chemical reaction examples are used to verify the proposed method. The calculation results show that compared with the traditional CVP method and literature results, the proposed method can reconstruct the time grid more effectively and find more accurate time switching points, leading to lower calculation cost and more accurate solution.

    Energy and environmental engineering
    Energy consumption analysis of novel pyrolysis method of sewage sludge based on microwave-induced target-oriented heating
    Chaoqian WANG, Wenlong WANG, Zhe LI, Jing SUN, Zhanlong SONG, Xiqiang ZHAO, Yanpeng MAO
    2019, 70(S1):  168-176.  doi:10.11949/j.issn.0438-1157.20181404
    Abstract ( 106 )   HTML ( 6)   PDF (889KB) ( 65 )  
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    There are many difficulties of current research on sewage sludge pyrolysis, such as time consuming, high energy consumption and limitation of char properties. To solve those difficulties, this paper provides a novel technical approach of microwave-induced synergistic pyrolysis. Namely without adding extra microwave absorbent, semi-pyrolytic sludge char can be obtained by pre-pyrolysis of sewage sludge itself under conventional low energy consumption; then it is used as basal body to be pyrolysed under microwave, which is based on in-situ carbonation enhancement by high-energy-site effects and heavy metal solidification via vitrification; finally, highly stable sludge char is expected to be produced with low energy consumption in the novel process. The paper tested the dielectric properties, proximate analysis, toxicity characteristic leaching procedure, specific surface area and SEM images of sewage sludge materials. By brief analysis and verification of feasibility of the novel approach, its energy consumption mechanism was focused on, which will contribute to practical application. In this experiment, semi-pyrolytic sludge char produced by pre-pyrolysis(700℃, 10 min) could increase whole dielectric properties by 22%, that was conductive to achieve average 900℃ in 5 min under microwave pyrolysis (900 W). That was helpful for improving properties of sludge char, and the novel pyrolysis process saved up to 50% than the traditional one (700℃, 60 min) . Energy saving property of the novel approach is mainly attributed to obviously shorten whole pyrolysis time and high efficiency utilization of microwave energy. This novel technical approach can complete the preparation of highly stable sludge char with low energy consumption, and will open a large-scale disposal route for sewage sludge.

    Spectrum changes of electromagnetic pluses in chemical reactions
    Xingpeng LIU, Dandan YAN
    2019, 70(S1):  177-181.  doi:10.11949/j.issn.0438-1157.20181405
    Abstract ( 47 )   HTML ( 1)   PDF (486KB) ( 16 )  
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    Microwave-assisted chemical reactions have been attractive. However, the problems of inhomogeneous heating have been preventing the further application of microwaves in chemical engineering. In order to solve these problems, the characteristics of electromagnetic wave propagation in chemical reactions need to be investigated. As a typical time-varying and non-equilibrium system, the dielectric properties of chemical reactions change during chemical reactions. Moreover, the frequency of the electromagnetic waves in the reactions can be influent by the variation of dielectric properties. In this paper, based on the polarization characteristics of the simple polar-molecule reactions, the propagation of electromagnetic pulses in the reactions with different reaction rates is simulated to disclose the effects of the time-varying and dispersive characteristics on the spectrum of electromagnetic pluses. For slow reactions, the time-varying characteristics are negligible, and the dispersive characteristics leads to the spectrum variation. For fast reactions, the time-varying and dispersive characteristics make the spectrum changes of electromagnetic pluses.

    Broadband permittivity measurement apparatus using substrate integrated waveguide structure
    Hu CHEN, Qian CHEN, Changjun LIU, Kama HUANG, Zhuo LONG
    2019, 70(S1):  182-185.  doi:10.11949/j.issn.0438-1157.20181379
    Abstract ( 53 )   HTML ( 2)   PDF (484KB) ( 26 )  
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    The microwave energy has been applied to chemistry, materials, and medicine since 1980s. The application of microwave energy is related with permittivity of materials. If the permittivity of materials is known, the absorption and reflection on microwave energy can be obtained. Hence the measurement for permittivity in microwave power applications is very important. However, the traditional measurements have some limitations on realtime measurement. The measurement apparatus has been proposed and the permittivity of materials has been reconstructed by modern optimization algorithm (artificial neural network). The applications of microwave energy have been extended by the valuable data gained. The research work will contribute to application of microwave power.

    Design and experimental study on silica gel-water adsorption air cooler
    Hongbin WANG, Jiajie PENG, Haiquan SUN, Quanwen PAN, Ruzhu WANG, Hailiang WANG, Zhaohong XU
    2019, 70(S1):  186-192.  doi:10.11949/j.issn.0438-1157.20181217
    Abstract ( 71 )   HTML ( 3)   PDF (600KB) ( 23 )  
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    The adsorption air cooler does not require the cooling water circuit and the cooling water pump, so it can meet the needs of miniaturized applications. In this paper, a silica gel-water adsorption air cooler was experimentally studied, which consists of two adsorbers, one condenser and one heat pipe type evaporator. The dynamic operating characteristics of the cooler were obtained. This paper discusses the influence of heat source temperature, cooling water inlet temperature and cold air outlet temperature on system performance. The experimental results show that the cooler can be effectively driven by low-grade heat source at 60—90℃. The cooling capacity of 0.84—2.29 kW and the corresponding COPs of 0.26—0.43 were achieved.

    Thermodynamics simulation of biogas fueled chemical looping reforming for H2 generation using NiO/Ca2Al2SiO7
    Daofeng MEI, Haibo ZHAO, Shuiping YAN
    2019, 70(S1):  193-201.  doi:10.11949/j.issn.0438-1157.20181282
    Abstract ( 76 )   HTML ( 3)   PDF (651KB) ( 45 )  
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    Thermodynamics analyses were carried out in biogas fueled chemical looping reforming (CLR) process for H2 generation, where the main component of cement Ca2Al2SiO7 was used as a support for NiO/Ca2Al2SiO7 oxygen carrier. Around 430 cases for CLR were studied via a home-built MATLAB? code, considering the effects of NiO loading yNiO, oxygen carrier circulation rate Fs, oxygen carrier conversion variation ΔXs, steam concentration xH2O and air reactor temperature TAR. The global enthalpy variation ΔH can be easily tuned to ΔH=0, i.e. CLRa state, by varying the (NiO+Ca2Al2SiO7)/biogas ratio. Under CLRa state, increase of TAR and ΔXs can lead to the decrease of H2 yield, while rising of Fs would result in the higher H2 yield. The simulation suggests that the optimized H2 yield of 1.57 (m3 H2)?(m3 biogas)-1 can be achieved with NiO loading lower than 10%(mass), TAR close to 1150 K, ΔXs lower than 0.25, Fs higher than 2 kg?s-1 and xH2O lower than 54.5%(vol). Heat balance of the global FR, AR and WGS reactors showed that the CLRa can be run under auto-thermal condition, meanwhile heat at exits of reactors can be recovered to be used in the preheating of gases entering reactors.

    Material science and engineering, nanotechnology
    Microwave synthesis and properties of dioctadecyl tetrahydroxyethyl dibromopropane diammonium
    Siyu PENG, Cheng ZHENG, Taoyan MAO, Yuan WEI, Huafeng SONG
    2019, 70(S1):  202-210.  doi:10.11949/j.issn.0438-1157.20181393
    Abstract ( 76 )   HTML ( 3)   PDF (665KB) ( 32 )  
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    A gemini surfactant called dioctadecyl tetrahydroxyethyl dibromopropane diammonium (DTDD) was synthesized via quaternization reaction under the condition of microwave and high pressure using octadecyl diethanolamine and 1,3-dibromopropane as the main raw materials. The target compound was characterized by IR and1H NMR, and its purity was determined by HPLC-ELSD. By analysing the single-factor and orthogonal array design experiments, the optimal synthesis conditions for the synthesis of DTDD by microwave method were determined as follows: microwave power was set to 900W, reaction time was 8h and reaction temperature was 140°C, reaching a yeild of 92%. Compared with the traditional heating method, the reaction rate using microwave synthesis was greatly increased. The critical micelle concentration (CMC), surface tension, Kraft point, and foam properties of the product and the traditional surfactant octadecylmethyldihydroxyethyl ammonium bromide (OMDAB) were determined. The performance test results showed that compared with OMDAB, the target product had good surface properties with the critical micelle concentration of 0.087 g/L and the corresponding surface tension γ(CMC) of 31.09 mN/m.

    Synthesis and application of carboxylic acid metal salt beta crystal nucleating agent
    Wenlin ZHAO, Jiebing HE
    2019, 70(S1):  211-216.  doi:10.11949/j.issn.0438-1157.20190062
    Abstract ( 57 )   HTML ( 5)   PDF (3203KB) ( 23 )  
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    A new type of carboxylic acid metal salt β-crystalline nucleating agent is developed. It is a new compound. This nucleating agent not only efficiently induces the formation of β-PP, but also has a high nucleation efficiency. The impact strength of β-nucleating PP can be increased by 2 to 4 times, and the heat deformation temperature of PP can be greatly increased. The contradiction between the impact strength and the thermal deformation temperature of polypropylene products is effectively relieved. At present, it has been widely used in PPR tubes and PPH plates, large injection products, and lithium battery diaphragm.

    Effect of nanoparticles on thermal properties of molten salt composite heat storage materials
    Qiang YU, Yuanwei LU, Xiaopan ZHANG, Yuting WU
    2019, 70(S1):  217-225.  doi:10.11949/j.issn.0438-1157.20181516
    Abstract ( 67 )   HTML ( 7)   PDF (1300KB) ( 27 )  
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    In order to study the effects of SiO2 nanoparticles content on the specific heat capacity and thermal conductivity of nano-SiO2/NaNO3-KNO3/EG composite heat storage materials, a series of nano-SiO2/NaNO3-KNO3/EG composites were prepared by mechanical dispersion method. NaNO3-KNO3 and SiO2 nanoparticles with different mass fractions (0.1%, 0.5%, 1%, 2%, 3%) were used as heat storage materials and expanded graphite (EG) was used as matrix material. Then the specific heat and the thermal diffusivity of composite heat storage materials were measured, and the microstructural characteristics were analyzed by scanning electron microscopy (SEM). The results show that adding 1% of SiO2 nanoparticles to the composite can significantly affect its average specific heat capacity and thermal conductivity, with a measured value of 3.92 J/(g·K) and 8.47 W/(m·K), respectively, which are 1.37—2.17 times and 1.7—3.2 times higher than that of the other similar composites. This is owed to its high density network nanostructure with the large specific surface area and high surface energy which can improve the specific heat capacity and thermal conductivity.

    Microwave synthesis and properties of dioctadecyldihydroxyethyl ammonium bromide
    Yanrao CHEN, Taoyan MAO, Cheng ZHENG
    2019, 70(S1):  226-234.  doi:10.11949/j.issn.0438-1157.20190005
    Abstract ( 71 )   HTML ( 3)   PDF (2498KB) ( 35 )  
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    Dioctadecyldihydroxyethyl ammonium bromide (DODAB) was prepared by microwave synthesis of octadecyldiethanolamine and bromooctadecane. The optimum synthetic conditions were determined as follows: the concentration of reactant was 2.17 mol·L-1, the reaction time was 158.61 min, and the microwave power was 626.06 W. Under these conditions, the predicted conversion was 93.71%. The product was characterized by IR and 1H NMR. The surface activity of the product is determined as follows: CMC=0.501 g·L-1, surface tension is 30.27 mN·m-1, which is better than cationic surfactant D1821. The results show that the softening effect of DODAB is similar to that of D1821. With the increase of treatment times, the softening effect of DODAB treatment is slightly weaker than that of D1821, but its hand feel is more natural and comfortable. At the same time, DODAB is better than D1821 in maintaining fabric whiteness and yellowing resistance.

    Synthesis of long chain alkyl xylene from coal to olefin
    Lei YAN, Siyu CHEN, Meiliangzi XIAO, Wei DING
    2019, 70(S1):  235-241.  doi:10.11949/j.issn.0438-1157.20190174
    Abstract ( 124 )   HTML ( 7)   PDF (557KB) ( 67 )  
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    The synthesis of long chain alkylated xylene from coal to olefin was studied by using a fraction of coal to olefin and mixed xylene as raw materials. Condition experiment method used to get the better process parameters are the initial reaction temperature of room temperature, the quality of the mixed xylene/coal to olefin ratio of 2∶3(equal to the amount of substance ratio of 2.2—2.5∶1), the catalyst for 1/110 of the total reaction liquid (mass fraction), the reaction time for 60 min, the long chain alkyl dimethyl benzene content in more than 80%. The average molecular weight was calculated to be about 302.5, equivalent to the average molecular weight of tetraalkylxylene, with a certain molecular weight distribution, which was a better raw material for the production of alkyl aryl sulfonate, and the amplification experiment was carried out in a 30 L reactor.

    Synthesis of 3-methyl-benzidine hydrochloride
    Ning QIN, Qing MIN, Kaiyuan SHAO, Wenxiang HU
    2019, 70(S1):  242-247.  doi:10.11949/j.issn.0438-1157.20190265
    Abstract ( 137 )   HTML ( 6)   PDF (497KB) ( 57 )  
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    3-Methyl-benzamidine hydrochloride is an important raw material and intermediate in the field of pesticide and pharmaceutical research. There are two routes to synthesize 3-methyl-benzamidine hydrochloride. The one is two-step synthesis method in which 3- methyl-benzonitrile and hydroxylamine hydrochloride react to generate 3-methyl-benzamil -doxime, and then its hydrogenation reduction occurs to get 3-methyl-benzamidine hydrochlor -ide. In the preparation of 3-methyl-benzamildoxime, the effects of conventional heating synthesis, microwave synthesis and ultrasonic synthesis were investigated. Another synthetic method is the reaction of sodium amide and 3-methyl-benzonitrile under reaction conditions close to absolute anhydrous. After the reaction was completed at room temperature, ammonium chloride was directly added to the reaction flask. This synthesis method was called one-pot method. The results were confirmed by the boiling point, MS and 1H NMR spectrum. The experimental results show that the yield relationship of the three synthetic methods for preparing 3-methyl-benzamidoxime in the two-step synthesis method is microwave synthesis > ultrasonic synthesis> conventional heating synthesis. The total yield of the two-step synthesis method was 58.05%, and the yield by one-pot synthesis was 78.19%. Both two-step synthesis and one-pot synthesis can be used to synthesize 3-methyl-benzamidine hydrochloride.

    Process safety
    Research on valve internal leakage monitoring based on single acoustic sensor
    Wenliang WANG, Fang WANG, Shi en WU, Weiguo LIN
    2019, 70(S1):  248-256.  doi:10.11949/j.issn.0438-1157.20190007
    Abstract ( 69 )   HTML ( 6)   PDF (879KB) ( 31 )  
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    Aiming at simulation and monitoring for valve internal leakage, a single-senor based non-intrusive acoustic monitoring method for valve internal leakage and a valve internal leakage simulation method are proposed. A virtual valve composed of a flange, thin paper sheet and perforated aluminum sheet is designed, which can truly simulate the transient leakage of a valve and overcome shortcomings in traditional valve internal leakage simulation method. By analyzing and comparing the frequency domain characteristics of the output signal of the upstream and downstream acoustic sensors under different conditions, the redundancy of the upstream acoustic sensor and the feasibility of single-sensor based acoustic monitoring method for valve internal leakage are verified. The time-frequency domain characteristics of the output signal of single acoustic sensor under different conditions are analyzed and compared, a time-frequency domain feature extraction method for acoustic signals based on wavelet packet energy fractionation and the kurtosis coefficient is proposed, the valve internal leakage diagnosis model based on support vector data description method (SVDD) was established with the normal samples under valve closed condition. The experimental results show that the proposed method for valve internal leakage monitoring with single acoustic sensor is effective, and it has strong anti-interference ability and high detection sensitivity.