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Table of Content
31 August 2016, Volume 67 Issue S1
    CIESC Journal (HUAGONG XUEBAO) Vol.67 No.S1 August 2016
    2016, 67(S1):  0-0. 
    Abstract ( 43 )   PDF (20110KB) ( 110 )  
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    Thermal management using phase change materials for proton exchange membrane fuel cells
    CHEN Sitong, LI Weiwei, WANG Xueke, WANG Shubo, XIE Xiaofeng, ZHU Tong
    2016, 67(S1):  1-6.  doi:10.11949/j.issn.0438-1157.20160623
    Abstract ( 150 )   PDF (1635KB) ( 403 )  
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    Proton exchange membrane fuel cell (PEMFC) has become the preferential choice of a new generation of energy and power for its high energy conversion rate and environment-friendly. Through analysis about the important influence of temperature on the operating performance of PEMFC, the importance of effective thermal management for fuel cell is proved. The current research status of PEMFC thermal management are induced and summaried according to the classification of active cooling and passive cooling. The material selection and the method of heat transfer enhancement is introduced in detail for the fuel cell thermal management system using phase change materials. And this paper forecasts the research direction of this field in the future.

    Progress of polymer solar cells and materials
    HU Hongchao, CUI Yingde
    2016, 67(S1):  7-21.  doi:10.11949/j.issn.0438-1157.20152002
    Abstract ( 131 )   PDF (1596KB) ( 673 )  
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    Energy and polution is the big problems of human, the best solution is that develop solar energy adequately. Polymer solar cells have been researched for over 20 years, the efficiency have overcome 10%。review the history and theory of polymer solar cells, the structure and materials are important factors for polymer solar cells, especially donor. From PPVs to PCDTBT, TTBDT, BDTTPD, the efficiency of solar cells increase quickly as the new donor material was used in polymer solar cells. It's important for putting into using that researching new donor material as the theory have be studied in a deep-going way and the technology mature.

    A new method for calculating time to maximum rate under adiabatic condition
    GUO Zichao, HAO Lin, WEI Hongyuan
    2016, 67(S1):  22-27.  doi:10.11949/j.issn.0438-1157.20151737
    Abstract ( 167 )   PDF (522KB) ( 523 )  
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    Time to maximum rate under adiabatic condition (TMRad) is a widely-used parameter for evaluation of the probability of decomposition reactions of substances or reactive mixtures under adiabatic conditions. The traditional method for calculation of TMRad necessitates the kinetics and thermodynamics of the decomposition reactions, such as pre-exponential factor, activation energy, reaction order and decomposition enthalpy. To calculate the TMRad using accelerating rate calorimeter (ARC), a whole thermal curve including both onset decomposition temperature and final temperature is required. However, due to the complexity of reaction mechanism or safe operation of calorimetric experiment, the final temperature is often unavailable, meaning the traditional method is in failure. Therefore, to solve this problem, this paper proposes a new method for calculating TMRad, which is based on the assumption that the consumption of reactants is negligible within a narrow temperature range relative to the whole exothermic curve. Moreover, the experiment results also prove the flexibility of this new method to exothermic curve including final temperature.

    Pool boiling heat transfer outside horizontal tubes at higher heat flux
    JI Wentao, ZHANG Dingcai, ZHAO Chuangyao, HE Yaling, TAO Wenquan
    2016, 67(S1):  28-32.  doi:10.11949/j.issn.0438-1157.20160706
    Abstract ( 99 )   PDF (936KB) ( 1185 )  
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    For the flooded evaporator in refrigeration or air conditioning systems, refrigerant is boiling on the shell side and water is flowing in the tube side. The pool boiling heat transfer coefficient of R134a outside one smooth tube and one reentrant cavity enhanced tube No.1 is investigated with an experimental approach. At the saturate temperature of 6, 10 and 16℃, the heat flux of 10-250 kW·m-2, the heat transfer coefficient versus heat flux of smooth tube is investigated and compared with Cooper correlation. The external diameter of smooth tube and enhanced tube are 15.93 mm and 25.36 mm, respectively. At the heat flux of 10-250 kW·m-2, it is found that the deviation of experimental result and Cooper correlation is within ±15%. the average value of m in hqm, is 0.67. For the enhanced tube, the enhanced ratio is the largest at the heat flux less than 40 kW·m-2. The enhanced ratio is decreasing as the increment of heat flux. At the heat flux larger than 250 kW·m-2, the heat transfer coefficient of enhanced tube is approaching the smooth tube, and even smaller than smooth tube.

    Numerical simulation on flow boiling heat transfer of R32 in micro/mini-channels
    ZHAO Ran, WU Xiaomin, HUANG Xiujie
    2016, 67(S1):  33-39.  doi:10.11949/j.issn.0438-1157.20160643
    Abstract ( 96 )   PDF (2533KB) ( 221 )  
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    Two dimensional unsteady numerical simulations of flow boiling heat transfer inside a 1 mm and 2 mm smooth horizontal tubes for R32 were conducted utilizing VOF multiphase model, under the condition of a mass flux of 100 kg·m-2·s-1, a heat flux of 12 kW·m-2, a saturation temperature of 15℃. Single phase flow, bubbly flow, slug flow were observed in the simulation results for R32 flow boiling heat transfer inside a 2 mm channel while single phase flow, bubbly flow, confined bubbly flow, slug flow were observed inside a 1 mm channel. Bubble movement characters and influences on flow boiling heat transfer basic patterns exerted by channel diameter during flow boiling heat transfer inside the tubes for R32 were analyzed based on the distributions of gas phase volume fraction and temperature generated by the simulations. A promising consistency was achieved through the comparison between numerical simulation and experimental results.

    Capillary pressure-saturation relation for gas-liquid two-phase fluid in spherical pore
    LIU Guiling, MIN Jingchun, TANG Yicun
    2016, 67(S1):  40-46.  doi:10.11949/j.issn.0438-1157.20160720
    Abstract ( 94 )   PDF (1474KB) ( 222 )  
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    The relationship between capillary pressure and saturation is one of the most basic and important issues of multiphase flow in porous media. The-state-of-the-art of theoretical models on capillary pressure-saturation relation as well as the progress of Leverett-J function are reviewed and discussed, and then the capillary pressure-saturation equations for liquid-gas two-phase fluid in a single spherical cavity are derived through geometry manipulation. Calculations are performed for solid-liquid contact angles of 10°, 30°, 60° and 90° using such equations, the obtained results are consistent with the experimental data in the literature, providing a rational explanation for the variation characteristics of the capillary pressure-saturation curve.

    Subcooled boiling in narrow channels with different sizes
    ZHAO Nan, ZHANG Wang, YANG Lixin
    2016, 67(S1):  47-56.  doi:10.11949/j.issn.0438-1157.20160641
    Abstract ( 94 )   PDF (2195KB) ( 168 )  
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    In present paper, the heat transfer characteristics of subcooled flow boiling in vertical rectangular narrow channels of different size at atmospheric pressure were investigated experimentally by using deionized water as working fluid, under the working conditions that width δ from 3 mm to 4 mm, mass flux G=143 & 300 kg·m-2·s-1, inlet subcooling ΔTsub=17 &25℃, heat flux q from 1 W·cm-2 to 20 W·cm-2. The visualization experiments were conducted to study the characteristics of bubble nucleation on the heating wall in the same area, then obvious channel size effects were found out, including effects on onset of boiling, heat transfer coefficient, active nucleation site density, bubble departure diameter and bubble departure frequency, etc.

    Influence of high-voltage electrostatic field on formaldehyde diffusion within cellulose Iβ
    XU Bo, CHEN Zhenqian
    2016, 67(S1):  57-62.  doi:10.11949/j.issn.0438-1157.20160609
    Abstract ( 92 )   PDF (2602KB) ( 265 )  
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    Under the effect of different high-voltage electric fields, the simulation of formaldehyde diffusion in cellulose Iβ was studied by molecular dynamics. Results showed that when electric intensity increased from 0 to 109 V·m-1, the diffusion coefficient increased from 5.64×10-10 m2·s-1 to 7.768×10-10 m2·s-1, an increase of nearly 38%. It showed that high-voltage electrostatic field strengthened the formaldehyde diffusion in cellulose Iβ and increased the diffusion coefficient. Electric intensity can strengthen the movement of cellulose chain. However, it will not undermine the stability of cellulose. The application of high-voltage electrostatic field altered the interaction between formaldehyde and cellulose Iβ, improving the electrostatic effect, van der Waals interaction and total interaction.

    Influences of primary nozzle diameter on steam ejector performance
    FU Weina, LIU Zhongliang, LI Yanxia, WU Hongqiang, TANG Yongzhi
    2016, 67(S1):  63-68.  doi:10.11949/j.issn.0438-1157.20160561
    Abstract ( 120 )   PDF (2102KB) ( 257 )  
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    The complex internal flow field of steam ejector was numerically simulated with commercial software FLUENT. The pressure and velocity variation of internal fluid in the flowing process were studied and analyzed. The influences of the mixing steam pressure and the outlet diameter of primary nozzle on the ejector performance of the steam ejector were discussed in a great length. It is found from the results that the entrainment ratio of the steam ejector remains constant first with the back pressure to its critical pressure and then decreases, nevertheless, the entrainment ratio initially increases sharply with the primary nozzle outlet diameter and then decreases after the outlet diameter exceeds a certain value. Therefore there exists a critical outlet pressure for the steam ejector that determines its operation states. The outlet diameter of main nozzle has an optimal range, in which the ejector obtains the best performance, and the dissipation loss of the shock wave is relatively small.

    Thermal and mechanical coupled keyholing process in moving plasma arc welding
    LI Yan, FENG Yanhui, ZHANG Xinxin, WU Chuansong
    2016, 67(S1):  69-75.  doi:10.11949/j.issn.0438-1157.20160614
    Abstract ( 68 )   PDF (2713KB) ( 134 )  
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    Due to the strong heating effect and arc force, plasma arc welding (PAW) can instantly melt metal material and then penetrate through the molten metal, forming a vapor-filled cavity called as "keyhole". The arc temperature is extremely high in keyhole, and thus a large percentage of heat is able to be transferred to the bottom metal through the keyhole. With respect to the moving PAW, a keyhole-tracking heat source was developed to reflect the nonuniform heat transfer due to welding movement. It consists of a double-elliptical heat flux on top surface and a lower developing conical heat source proportional to the keyhole growth. The volume of fluid (VOF) method was applied to track keyhole interface, and the heat source was auto-controlled according to keyhole depth. By numerical simulation, heat transfer during the keyholing process was revealed and corresponding temperature field was calculated to display the thermal-physical mechanism in moving PAW. Moreover, keyhole evolution and molten metal flow in weld pool were also investigated to exhibit how the keyhole promotes deep penetration welding. Finally, experiment was carried out on stainless steel plate of thickness 8 mm, and the measured weld geometry and size coincide with simulation results.

    Numerical predictions of sulfuric acid corrosion on novel heat transfer surfaces
    WANG Yuchen, TANG Guihua
    2016, 67(S1):  76-83.  doi:10.11949/j.issn.0438-1157.20160603
    Abstract ( 97 )   PDF (1209KB) ( 185 )  
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    Low temperature corrosion determined by the sulfuric acid dew point temperature and the sulfuric acid vapor and water vapor condensation rate is an important reason denoting the failures of heat transfer equipment. In this study, the sulfuric acid dew point temperature and sulfuric acid vapor and water vapor condensation rate on the wall and fin surface are calculated by considering both the vapor-liquid equilibrium effect and multi-component diffusion effect. In addition, the local distribution of acid dew point temperature on the fin surface is numerically predicted. It provides a precise guidance for the design of heat exchanger. The results show that the acid dew point temperature is affected by the factors of fuel type, fly ash particle (size and quantity) and structure of heat transfer fins. The fuel type, which affects the flue gas compositions and the combustion temperature, plays an important role on the sulfuric acid dew point temperature. The condensation of the sulfuric acid vapor on the ash particle surface leads to the decrease of sulfuric acid dew point temperature. The studied novel heat transfer fins (the H-type fin with compound dimples and rectangular longitudinal vortex generators) can reduce the local sulfuric acid dew point temperature and the sulfuric acid vapor and water vapor condensation rate on the fin surface.

    Natural convection in cylinder with internal slotted annulus under different structures
    SHEN Chunyun, LU Tingkang, DAI Zhenghua, YANG Mo
    2016, 67(S1):  84-90.  doi:10.11949/j.issn.0438-1157.20160671
    Abstract ( 59 )   PDF (3529KB) ( 203 )  
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    SIMPLE algorithm was used to simulate natural convection in a cylinder with an internal slotted annulus under different slotted structures, the influence on the heat transfer and fluid flow was studied when changing slotted degree and radius ratio. The results showed that under the same conditions calculated numerical results were in good agreement with the existing experimental results. The slot can enhance the heat transfer, but not slotted degree the greater the better. Radius ratio influenced on the heat transfer, showing that the radius ratio was smaller, the annular space more narrow, so the heat transfer effect was worse. With the increase of the radius ratio, the Keq increased obviously, but when the radius ratio exceeded 2, the Keq remained the same.

    Boiling effect of liquid droplet under high temperature radiation
    SUN Fengxian, LIU Changyu, XIA Xinlin
    2016, 67(S1):  91-96.  doi:10.11949/j.issn.0438-1157.20160632
    Abstract ( 82 )   PDF (1027KB) ( 211 )  
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    For a liquid droplet in high temperature surroundings of airflow convection and thermal radiation, the heat and mass transfer model of heating and evaporation has been established. The homogeneous boiling criterion was combined with the evaporation model to predict the inside boiling effect of droplet. A computer code was developed to solve the combined governing equations numerically. After verifying, the temperature rising and evaporating process of an n-dodecane droplet were simulated, in which the thermal expansion and property dependence on temperature were considered. The occurrence of boiling inside droplet is investigated for various high temperature conditions of convection and thermal radiation. The results show that the heating of high temperature convection and thermal radiation can both rapidly rise the temperature of droplet and the evaporation is accompanied by an obvious size expansion. Different from the convection heating, however, the thermal radiation can result in more rapidly rising of temperature inside the droplet. When the radiative temperature is high enough and the temperature of convective airflow is lower, the boiling will take place inside the droplet whose radius is not very small. It is also found that the droplet superheat need for boiling increases with the evaporating process.

    Weak coupled heat and mass transfer on adsorptive heat exchanger
    TU Yaodong, GE Tianshu, WANG Ruzhu
    2016, 67(S1):  97-102.  doi:10.11949/j.issn.0438-1157.20160768
    Abstract ( 72 )   PDF (1154KB) ( 182 )  
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    Traditionally, heat and mass transfer on adsorptive heat exchanger (AHE) is believed to be coupled, the concept of which makes it is hard to design and control the AHE optimally. Here, a novel concept of weak coupled heat and mass transfer is proposed to explain the dynamic behaviors of heat exchanging and moisture removal on AHE, which is based on a lumped parameter method and confirmed by experiments. In this way, heat exchanging and moisture removal can be view as two distinct processes that show great helpful to flexible design of the heat pump with AHE.

    Inverse heat conduction problem based on least squares prediction
    WANG Linlin, LU Mei, HUANG Jian
    2016, 67(S1):  103-110.  doi:10.11949/j.issn.0438-1157.20160535
    Abstract ( 78 )   PDF (2331KB) ( 156 )  
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    With thermo-gram, parameters of tumor inside can be estimated, and an inverse heat conduction model with unknown inner heat source could be obtained from it, and the solving process need a large number solutions of the heat conduction problem, where temperature field in the sub-domain is calculated. For 3D model, it needs a relatively long time. Particle swarm optimization combined with least square methods was applied to solve the inverse problem, in which least square method was used to predict particle's value of fitness function. During the solution process, some of the particles are going to be excluded from the group, by the judgment of new definition of distance. Hence, these particles' positions were rearranged. This method consumes less time than the modified PSO mentioned above, without sacrificing accuracy. Prediction coefficient was analyzed to find how it influences the searching process. So linear decreasing prediction coefficient was applied. Numerical verification shows that above method can reduce the numbers of solution of heat conduction, shorten the solving time, without sacrificing accuracy.

    Performance analysis of novel honeycombed plate heat exchanger based on entransy dissipation resistance
    ZHANG Cancan, WANG Dingbiao, HAN Yong, XIA Chunjie
    2016, 67(S1):  111-116.  doi:10.11949/j.issn.0438-1157.20160539
    Abstract ( 83 )   PDF (2642KB) ( 264 )  
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    The plate heat exchangers are widely used in industrial applications. A novel honeycombed plate heat exchanger is experimentally and numerically investigated in this research. The numerical results have been validated with the experimental values at a reasonable range. The internal velocity field of novel honeycombed plate heat exchanger is changed periodically, which increase the fluid turbulence intensity. The experimental results indicate that the entransy-dissipation is inversely related to its thermal resistance in novel honeycombed plate heat exchanger. The results of the current study provide a useful reference data for future design optimization of the novel honeycombed plate heat exchanger.

    Mathematical model on characteristics of V groove molten pool during MIG welding
    PENG Jingnan, YANG Lixin
    2016, 67(S1):  117-126.  doi:10.11949/j.issn.0438-1157.20160625
    Abstract ( 74 )   PDF (2302KB) ( 205 )  
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    Through analyze the MIG groove welding process and the welding experimental result, the physical process of 3D welding was simplified as a two dimensional mathematical model. For mathematical model establishment, based on the analysis of experimental results, established a two-dimensional mathematical model of welding seam section welding physical process. This model included the welding heat source model and molten pool phase change flow CFD model. The moving Gauss heat source model was used to describe the heat effect of arc and workpiece. By introducing scalar of liquid fraction, mushy region dynamic character which was described using "Darcy" model proposed for porous media, and phase change which was taken into account using source-based method, new CFD model was established to simulate transient heat and mass transfer phenomena in welding process. Comparative analysis the numerical simulation result and the metallographic figure, corrected the moving gauss heat source model parameters. Analyze the molten pool shape influenced by thermal buoyancy and Marangoni force in CFD model. Through comparative analysis the results of numerical simulation and experimental, verified the accuracy of the mathematical model. A further discussion on Gauss heat source parameters and the driving force mechanism model of molten pool flow was made. Results showed that through the reasonable model parameters selection, two-dimensional mathematical model can accurate analysis the evolution of V groove molten pool during MIG welding.

    Numerical study of hydrodynamic and heat transfer characteristics of gas-liquid Taylor flow in a 0.5 mm capillary
    SHI Yanping, ZHANG Jingzhi, LI Wei
    2016, 67(S1):  127-133.  doi:10.11949/j.issn.0438-1157.20160617
    Abstract ( 61 )   PDF (1086KB) ( 215 )  
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    The hydrodynamic and heat transfer characteristics of the fully-developed gas-liquid Taylor flow in a 0.5 mm capillary were studied numerically using the moving frame method. The bubble shapes, pressure drops and heat transfer characteristics were analyzed. The numerical results show that the liquid film thickness, the bubble length and the length of the unsteady region near the bubble tail increase with increasing Re. The effect of void fraction ξg on the bubble shapes is insignificant, while a longer bubble is expected at a higher ξg. The frictional factor f which is higher than the single-phase flow decreases with increasing Re and ξg. The average Nusselt number increases with increasing Re, while the increasing trend decreases with increasing Re. Nutp decreases linearly with increases in ξg and Nutp is about 1.2 to 3 times of that for the single-phase flow which means that Taylor flow can enhance heat transfer.

    Triangular winglet strengthen heat transfer characteristics of solar chimney power plants with vertical collectors
    ZHOU Yan, DONG Haoran, WANG Li, LI Qingling
    2016, 67(S1):  134-141.  doi:10.11949/j.issn.0438-1157.20160621
    Abstract ( 81 )   PDF (2189KB) ( 179 )  
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    In this paper,triangular winglets strengthening the unsteady natural convection flow and heat transfer, which were set up on the collector surface in the solar chimney power plant system, was researched with numerical methods. The number of ribs, rib inclination and arrangement influence on the temperature and velocity difference of the airflow between the inlet and outlet were analyzed. And heat effects of the triangular winglets were evaluated combining with the principle of field synergy. The results show that:With air flowed through the triangular winglets, the temperature gradient increases, the heat transfer is enhanced, the temperature and velocity difference of the airflow between the inlet and outlet increases sharply. As the number of ribs increased, the synergy angle between velocity and temperature gradient decreased because the disturbed effect enhanced, but energy loss increased as the flow friction increased, and when rib inclination is 45°, the velocity difference between inlet and outlet is the largest. With triangular winglets arranged in the vertical rectangular channel, staggered arrangement is better than the aligned.

    Heat transfer enhancement of heat tube with variable cross-section
    WANG Ke, DONG Xiaolin, XU Weifeng, LIU Zunchao, LIU Minshan
    2016, 67(S1):  142-147.  doi:10.11949/j.issn.0438-1157.20160785
    Abstract ( 74 )   PDF (1570KB) ( 184 )  
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    The issue of heat transfer enhancement is analyzed for the widely existed problem of the low heat transfer coefficient of laminar convective heat transfer in tubes. A new type of tube with variable cross-section is introduced under the directions of the heat transfer enhancement principles. Models of new tubes with variable cross-section under different parameters and general round tube are established. With large CFD analysis software FLUENT, and the influence on laminar convective heat transfer in tubes of new variable cross-section heat exchange tubes are investigated. Results show that the new tubes with variable cross-section could markedly enhance the laminar convective heat transfer of the tube side with less additional increase of flow resistance, and has a better synthetic performance of heat transfer enhancement. Within the scope of this study, Nu and η of new heat tubes both increase with the decrease of L1/di or L2/di, and η of new heat tubes is greater than 2.22. The results provide a certain guidance and theoretical basis for the enhancement of laminar convective heat transfer in tubes.

    Mass transfer of positive vanadium ions across cell membrane under magnetoelectric composite field
    ZHU Le, QI Liang, YAO Kejian, XIE Xiaofeng
    2016, 67(S1):  148-158.  doi:10.11949/j.issn.0438-1157.20160711
    Abstract ( 66 )   PDF (1219KB) ( 233 )  
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    The mass transfer of positive vanadium ions across Nafion117 membrane within the magnetic field, electric field, and other additives complex field were studied. Diffusion coefficients were estimated based on experimental data based on the Darcy's Law. The results show that the forward electric field will increase the permeability of vanadium ions. The permeability within an electric field density was estimated to be 30 V·m-1 which is 2.53 times as large as that without applied electric field. A non-uniform magnetic field can significantly help reduce the permeability of vanadium ions. When the non-uniform magnetic and electric fields are applied simultaneously, the effects of non-uniform magnetic field on the mass transfer are more noteble. A higher concentration of sulfuric acid solution contributes more to reduce the permeability of VOVO2+. Permeability of VOVO2+ are also decreased by mixing in glycerol, ligninsulfonate and other cathode electrolyte additives.

    Numerical analysis of temperature frequency characteristics of surface acoustic wave sensor
    LI Yingge, MA Lianxiang, ZHANG Na, YUAN Shikui, DU Dongxing
    2016, 67(S1):  159-165.  doi:10.11949/j.issn.0438-1157.20160555
    Abstract ( 61 )   PDF (2816KB) ( 235 )  
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    Numerical simulation has been carried out concerning the temperature frequency characteristics of a surface acoustic wave (SAW) sensor with ANSYS software. The internal temperature distribution of delay line surface acoustic wave sensor with Si/AlN/Al structure was analyzed under a certain pressure. The results show the effect of natural convection on the temperature field and stress field distribution in the sensor is small. The relationship between the temperature and the output resonant frequency is also simulated. According to the data fitting, the output series resonant frequency of the SAW sensor has a good linear relationship with the environmental temperature, so it can be used in the precise measurement of the temperature.

    Interfacial thermal resistance in mesoporous composites and its thermal conductivity
    LI Jing, FENG Yanhui, ZHANG Xinxin, WANG Ge
    2016, 67(S1):  166-173.  doi:10.11949/j.issn.0438-1157.20160601
    Abstract ( 102 )   PDF (2260KB) ( 212 )  
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    The interface widely exists in composite material, and it plays a decisive impact on the thermal properties of mesoporous composite material. Study on the thermal conductivity of the interface is very important to know and understand the heat transfer mechanism of mesoporous composite material. In this paper, the simulation method of non-equilibrium molecular dynamics was used to calculate the interfacial thermal resistance between base material and filler in the mesoporous composite material, and the interfacial thermal resistance was analyzed with different temperature and different quality of material. Furthermore, the interfacial thermal resistance was used to modify the effective thermal conductivity of the mesoporous composite material. The results showed that the magnitude of the interfacial thermal resistance was 10-11m2·K·W-1 and it would gradually decrease with the temperature increasing. Since temperature increasing leads to the phonons' number increasing at the interface, the number and the energy of phonons penetrating the interface will increase. The greater the difference of the interface material quality, the higher the interfacial thermal resistance. The effective thermal conductivity of the mesoporous composite material can be decreased by downsizing the pore diameter, reducing the length of nanowires, increasing the distance between the nanowires or reducing the filling rate of the nanowires.It can be seen that, with the increasing of the pore size, the effective thermal conductivity of the mesoporous composite of the Z direction decreases, and those of X direction and Y direction have no obvious change. The effective thermal conductivity considering the interfacial thermal resistance is smaller than that without consideration, so it will be known that the interfacial thermal resistance can reduce the thermal conductivity, especially under the small pore diameter. The percentage of the interfacial thermal resistance is between 1%-7%, which will drop off gradually with the increasing of pore size. The effect of reducing the thermal conductivity through the interfacial thermal resistance will be more significant by decreasing the pore diameter and the distance between the nanowires, or increasing the length of nanowires and the filling rate.

    Effect of particle distribution on heat and mass transfer inside adsorption heat transformer
    XUE Bing, YAO Zhimin, SHENG Zunrong, MENG Xiangrui, WEI Xinli
    2016, 67(S1):  174-180.  doi:10.11949/j.issn.0438-1157.20160604
    Abstract ( 69 )   PDF (1052KB) ( 168 )  
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    Adsorption heat transformer with zeolite-water working pair has been proposed to directly generate high-temperature superheated steam from unsaturated hot water. A concept of direct-contact method between adsorbent and working fluid is adopted in order to enhance heat transfer inside the packed bed with porous adsorbent. Steam generation process is modeled to investigate dynamic behavior by combining mass, heat and momentum governing equations. Three-phase calculations of zeolite, water and gas are performed in zeolite-water and zeolite-gas regions connected by a moving water-gas interface. Two typical packed bed with different particle distributions are presented for numerical discussions:fine-coarse bed (F-C bed) and coarse-fine bed (C-F bed). Overall mass of generated steam are the same for the two kinds of beds. In F-C bed steam generation rate is faster but generation time is shorter. Time ratio of steam generation to water input is 58.8% in F-C bed. Superheated steam at 249℃ with gross temperature lift of 139℃ is achieved for both beds. All of the steam is generated at the maximum value for F-C bed, while only one-third of that could be obtained at the peak for C-F bed. Mass ratio of generated steam from the outlet to the moving water-gas interface is larger for F-C bed. It's thus concluded F-C bed is more effective for steam generation with a considerable temperature lift.

    Foam lamellae flow rheology in converging-diverging tubes
    DU Dongxing, ZHANG Jian, SU NRui, WANG Chengcheng, ZHANG Jian, LI Yingge
    2016, 67(S1):  181-185.  doi:10.11949/j.issn.0438-1157.20160570
    Abstract ( 82 )   PDF (1041KB) ( 114 )  
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    Corresponding to the foam flow characteristics in the reservoir media, experimental studies were carried out concerning CO2 and N2 foam lamellae flow rheology in a converging-diverging tube. Non-dimensional parameters of ΔpD/δ and (3μU/σ)2/3 were determined based on two-phase assumption of the foam fluid. Clear linear relationships between the two non-dimensional parameters were observed for both CO2 and N2 foam lamellae flow with various threshold values, which indicates startup pressure is needed to initiate the foam flow. Compared to CO2 foam, N2 foam shows higher flow resistance. While compared to the case in a straight tube, the lamellae flow in the tube with varying diameters has higher pressure drops. It is concluded instead of the power law model, the Herschel-Bulkley type rheology model could be more suitable for describing foam flow mechanism in porous media.

    Performance of regeneration processes of internally heated regenerator and adiabatic regenerator
    WANG Qin, WU Wei, LIU Songsong, GU Chenjie, CHEN Cong, TANG Zhibiao
    2016, 67(S1):  186-194.  doi:10.11949/j.issn.0438-1157.20160602
    Abstract ( 101 )   PDF (1117KB) ( 142 )  
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    In this study, an internally heated counter-flow regenerator with coil tube as support of the packing is used in the novel hybrid liquid desiccant air conditioning system with sectional utilization of condensation heat to improve the effectiveness of the regeneration process. Such an internally heated counter-flow regenerator has been fabricated and tested with lithium chloride solution as liquid desiccant. The effect of the solution temperature and flow rate, air temperature and flow rate on the regeneration rate and regeneration thermal efficiency were discussed, and the results demonstrate that it would be better to avoid improving regeneration effectiveness by heating the regeneration air. Performance comparisons showed that performance of the internally heated regenerator was superior to the adiabatic one.

    Analysis on compound heat transfer enhancement performance in outward convex corrugated tube with twisted insert
    HAN Huaizhi, SONG Fuyuan, ZHANG Guolei, YANG Longbin, LI Yanjun
    2016, 67(S1):  195-202.  doi:10.11949/j.issn.0438-1157.20160575
    Abstract ( 102 )   PDF (3148KB) ( 167 )  
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    The flow and heat transfer characteristic in outward convex corrugated tube combined with insert twisted tube (CT) was numerically studied based on the three-dimension RNG k-ε model. A comparison is proposed between the numerical results and experimental results in order to check the reliability of numerical model. Comparative study on flow and heat transfer between the CT and conventional smooth tube (ST) is performed in order to review the compound heat transfer enhancement mechanism. The results show that compared with ST, the heat transfer performance and overall heat transfer performance of CT increase by 1.48 and 1.3 respectively, and more obvious in the low Reynolds number. Detached vortex is formed between the corrugatoion and twisted tape in CT, breaking the thermal boundary layer. Disturbance is increased by twisted tape in the main flow region, meanwhile, turbulence kinetic energy increase. Therefore, compound heat transfer enhancement is achieved by synergistic effect between the corrugation and twisted tape.

    Heat transfer characteristics of micro-encapsulated phase change material suspension in mini-tubes
    ZHONG Xiaolong, LIU Dong, XU Hailun
    2016, 67(S1):  203-209.  doi:10.11949/j.issn.0438-1157.20160567
    Abstract ( 79 )   PDF (4104KB) ( 245 )  
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    The heat transfer characteristics of 10% micro-encapsulated phase change material suspension(MEPCMS) and distilled water in the mini-tube of radius 1 mm and 2 mm were investigated. It appears that:for Reynolds number ranging from 400 to 1000, the local Nusselt number of MEPCMS and water in 1 mm tube is smaller than it in 2 mm tube. From the analysis of reason it is mainly because the thickness of 1 mm tube is larger than 2 mm tube resulting in stronger axial thermal conductivity. The distilled water joined in MEPCM in 1 mm tube can enhance the heat transfer between the fluid and tube wall and the local Nusselt number increase with Reynolds number increasing. While the 10% micro-encapsulated phase change material suspension in 2 mm shows weaker heat transfer characteristics than distilled water and the local Nusselt number decrease with Reynolds number increasing.

    Experimental and comparative research on flow past bluff bodies in transition flow
    ZOU Shuai, XU Jiahui, ZHOU Jie, XI Guannan
    2016, 67(S1):  210-216.  doi:10.11949/j.issn.0438-1157.20160611
    Abstract ( 53 )   PDF (5241KB) ( 231 )  
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    In order to investigate the characteristics of flow past bluff bodies, an open water tunnel which appears to the flow condition is designed, the PIV(particle image velocimetry) and dyeing methods are introduced to complete the flow visualization. Insight 4 G software can take control of the experimental process strictly. The stability of the experimental apparatus is proved by detecting the flow state on laser plane at different heights in the water channel. The instantaneous flow in different Reynolds number and the periodic characteristic visualization at Re=200 for single cylinder are carried out to validate the correctness of visualization method. Flow field characteristics of circular and square cylinder under the condition of different Reynolds number have been revealed. Comparing the image with the existing simulation and experimental results verifies the accuracy of the particle image velocimetry and dyeing method. Analyze the difference and connection of the flow characteristics of circular and square cylinder to find the universal law and difference in flow past single bluff bodies. In the periodic flow past a cylinder experiment,the periodic rotation of positive and negative vortexes appear alternately. In a cycle, the positive vortexes are gradually formed, enhanced and dissipated, the negative vortexes are also developed in the corresponding position. Flow around a single circular cylinder has no fixed separation point while flow around a single square cylinder has fixed separation point before or after the sharp edges.

    Two-way fluid solid interaction numerical analysis of steam generator heat transfer tube
    ZHAO Yingjie, SUN Baozhi, SHI Jianxin, GAN Yiran, LIU Shanghua
    2016, 67(S1):  217-223.  doi:10.11949/j.issn.0438-1157.20160466
    Abstract ( 82 )   PDF (1499KB) ( 208 )  
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    Taken the steam generator of Daya Bay nuclear power plant as the prototype, two-way fluid solid interaction of steam generator heat transfer tube together with the primary and secondary side was numerically simulated. The results show that the two-way fluid solid interaction method adopted here can accurately capture the displacement variation of steam generator heat transfer tube. The biggest displacement of heat transfer tube is located at the center section. The tube deviates to the third quadrant at equilibrium state. Displacement in X direction is not equal to that in Y direction because of the fluid elastic instability. The stress intensity along the height of heat transfer tube is symmetrically distributed with respect to center section (0.5 m). Stress concentration occurs adjacent to the fixed support due to the effect of fixed constraint, so stress near the fixed support is biggest. The distribution regularities of stress intensity along the circumferential direction at different height are similar. Affected by the displacement of heat transfer tube, stress intensity is symmetrically distributed with respect to the line 20° and 200° connected. Stress extremum occurs adjacent to the angle of 20° and 200°. Two-way fluid solid interaction method of steam generator heat transfer tube can provide theoretical reference for the safety operation of steam generator.

    Mass transfer performance for multiple-impeller bioreactor in cold model and fermentation experiments
    XIE Minghui, LU Hongzhong, TANG Wenjun, XIA Jianye, ZHANG Siliang, ZHOU Guozhong, YU Peiqing
    2016, 67(S1):  224-231.  doi:10.11949/j.issn.0438-1157.20151809
    Abstract ( 90 )   PDF (1658KB) ( 253 )  
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    Carboxyl methyl cellulose (CMC) solutions with different concentrations simulating different mycelial fermentation broth were used for the study of mass transfer characteristics in bioreactor. Two impeller combinations (triple Rushton turbines, 3PY and bottom hollow blade turbine combined with upper two up-pumping hydrofoils (3 blades), HY+2KCXu) were employed. Under low CMC concentration condition, impeller combination of HY+2KCXu showed better mass transfer capacity. Fermentation of Aspergillus niger with production of glucoamylase was conducted under the two impeller combinations. In order to keep the similar oxygen uptake rate (OUR) among the two combinations, impeller rotation speed of the two configurations was adjusted respectively. Ultimately, based on the investigation of enzyme production, biomass amount, broth rheology and also mass transfer capacity of impellers, conclusions were gotten:apparent viscosity of broth in fermentation with HY+2KCXu was lower than that with 3PY. It seemed that in fermenter equipped with HY+2KCXu pellet prevailed than mycelia, thus lower viscosity was resulted, which in turn increased the mass transfer capacity of the system, that may be the reason why this impeller combination can gave higher product titer.

    Numerical simulation of multi-flow and heat transfer characteristics in heat exchangers with triple-helical baffles
    DUAN Zhenya, SHEN Feng, ZHANG Junmei, SONG Xiaomin, CAO Xing
    2016, 67(S1):  232-238.  doi:10.11949/j.issn.0438-1157.20160215
    Abstract ( 78 )   PDF (1793KB) ( 247 )  
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    Triple helical baffle heat exchanger was proposed to arrange more helical baffle in shell side with large helix angle and enhance heat transfer rate. In this paper, the flow characteristics and heat transfer performance of heat exchangers with triple helical baffles were analyzed. The comprehensive performance between single-helical and triple-helical baffle heat exchangers were compared based on the calculating results of pressure drop and heat transfer coefficient when Reynolds number ranges from 1391-4174. The results showed that:heat transfer coefficient and JF factor of triple-helical baffle heat exchangers is 27.9% higher and 13.67% higher than single-helical baffle heat exchanger respectively. Besides entransy dissipation theory was used to analyze the heat transfer performance of triple-helical baffle heat exchanger with different helix angle, and triple-helical baffle with 64.8° got the lowest entransy dissipation rate. The heat transfer rate of central tube and outer tube were compared, outer tube have higher heat transfer rate compared with central tube.

    Numerical analysis of dryout and post-dryout heat transfer in once-through steam generator
    SHI Jianxin, SUN Baozhi, ZHAO Yingjie, LIU Shanghua, ZHANG Linlin
    2016, 67(S1):  239-245.  doi:10.11949/j.issn.0438-1157.20160519
    Abstract ( 87 )   PDF (1941KB) ( 236 )  
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    It is significant to accurately predict the flow boiling and dryout for the design, safe and reliable operation of once-through steam generators. The once-through steam generator of B&W company is simplified reasonably, the two-fluid three-flow-field mathematical model and wall heat flux partition model are introduced to simulate the flow boiling in actual steam generator based on constant heat flux and coupled method respectively. The results show that:Heat transfer performance declines sharply when dryout occurs, soaring maximum of the wall temperature at constant heat flux is considerable (about 300 K·m-1), while a soaring maximum of 25 K·m-1 at coupled method, which is consistent with the actual operating process. The subcooled boiling occurs in preheating region at both thermal boundaries and the heat transfer methods near the wall consist of liquid convective, evaporation and quenching heat transfer. The main heat transfer method in nucleate boiling region is evaporation, accompanied with liquid convective and quenching heat transfer. The liquid convective and quenching heat transfer all drop to 0 when dryout occurs and the heat transfer method is vapor phase convective heat transfer in post-dryout heat transfer region.

    Condensation with non-condensable gas in horizontal rectangular channel
    CHENG Funing, DAI Renkun, WEN Jianjun, YIN Zhan, ZENG Min, WANG Qiuwang
    2016, 67(S1):  246-252.  doi:10.11949/j.issn.0438-1157.20160882
    Abstract ( 100 )   PDF (1011KB) ( 208 )  
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    The influence of N2 mass fraction, coolant mass flux and mixture mass flux on condensation heat transfer in the horizontal rectangular channel have been investigated, with the mixture mass flux ranging from 38 kg·m-2·s-1 to 132 kg·m-2·s-1. The results show that when the steam flows at high speed, the deterioration of noncondensable gas on the condensation heat transfer is relatively decreased, 8% noncondensable gas results in the reduction of 26.4% in condensation heat transfer coefficient. The condensation heat transfer coefficient increases with the increase of the mixture mass flux and decreases with the increase of the coolant mass flux. Moreover, the variations of the condensation heat transfer along the mixture flow direction are also obtained, the results show that the local condensation heat transfer coefficient decreases along the mixture flow direction.

    Molecular dynamics simulation on effect of different carboxylic acid group contents on norbornene derivatives proton exchange membranes bearing bifunctional groups
    FENG Zhiming, LI Weiwei, LI Xue, ZHAO Yang, XIE Xiaofeng, CHAI Chunpeng, LUO Yunjun
    2016, 67(S1):  253-259.  doi:10.11949/j.issn.0438-1157.20160658
    Abstract ( 67 )   PDF (4279KB) ( 143 )  
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    A bifunctional group proton exchange membrane(PEM) was constructed in this paper with sulfonic and carboxylic acid groups based on polynorbornenes on the software platform of Material Studio (MS). The effect on the properties of PEM were studied by changing the different proportion of three structural units 4-(bicyclo[2.2.1]hept-5-en-2-yl) benzene-1-sulfonylchloride (NBSC), dimethyl 8,9,10-rinorborn-5-ene-2,3-dicarboxylate (DCNM) and DCNM-N. Meanwhile, the microscopic structure of the membranes and the transport properties of the small molecules were analyzed. The result shows that the MSD of H2O as well as H3O+ and diffusion coefficients augment gradually with the reducing of carboxylic acid group contents which are the results of the hydrogen bonds interaction among the different components. Besides, under the synergistic action of sulfonic acid and carboxylic acid at 298 K, the proton conductivitise of the three proton exchange membranes are 22.75, 46.14 and 56.77 mS·cm-1 respectively which indicates that proton conductivity rises with the aggrandizement of the number of carboxylic acid group, while the growth rate increases first and then decreases.

    Mechanism of nitric oxides reduction by carbon monoxide over cobalt oxides supported by CeO2 nanorod
    WANG Luyuan, CHENG Xingxing, ZHANG Xingyu, MA Chunyuan
    2016, 67(S1):  260-269.  doi:10.11949/j.issn.0438-1157.20151657
    Abstract ( 132 )   PDF (3356KB) ( 251 )  
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    CeO2 nanorod was synthesized by a hydrothermal method in alkaline solution and cobalt oxides were loaded on CeO2 via wet impregnation methods. In order to study the effects of precursor concentration, the catalytic performances and chemical-physical characteristics of catalysts were investigated. The results indicated that the optimal precursor concentration was 10% (mass). After systematically comparing chemical-physical properties detected by nitrogen physisorption, XRD, XPS, TEM, with deNOx performance, it can be found that Co2O3 was most effective component in the catalysts and increasing its fraction could greatly promote the deNOx activity. The existence of the CoO had negative effect to the CO and NOx reaction while Co3O4 caused N2O generated at a lower temperature.

    Effect of modification of α-alumina carrier with titania on catalyticperformance of silver catalyst for ethylene selective oxidation
    JIANG Jun
    2016, 67(S1):  270-275.  doi:10.11949/j.issn.0438-1157.20151680
    Abstract ( 86 )   PDF (2158KB) ( 439 )  
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    In order to exclude the effect of pore structure of carrier, effect of modification of α-alumina with titania on catalytic performance of silver catalyst for ethylene selective oxidation reaction was studied carefully. Experimental results showed that the specific surface area and the pore structure of the carriers were almost unchanged after modification with titania, but silver was dispersed more evenly on the modified carrier than on the α-alumina and the interaction discovered stronger between the modified carrier and silver than between α-alumina and silver. Modification of alumina with titania deteriorates the catalytic performance and was unfavorable to the performance of non-promoted silver catalysts. But it was beneficial to the catalytic performance of the promoted silver catalysts prepared by co-impregnation method. Research results revealed that decrease of IEP (isoelectric point) for the modified carrier and the strong interaction between the carrier and silver are responsible for the even and good dispersion of silver on the modified carrier. In presence of promoters, the interaction between the carrier and silver is weakened and the oxidation and isomerization side-reactions of ethylene oxide are abated, which jointly improve the catalytic performance of the promoted silver catalyst.

    Oligomerization of isobutene catalyzed by ionic liquid consisting of anhydrous iron trichloride
    YANG Shuqing, ZHENG Xianmin, WANG Luhui, ZHANG Renkun, WANG Dongguang
    2016, 67(S1):  276-282.  doi:10.11949/j.issn.0438-1157.20160424
    Abstract ( 85 )   PDF (1022KB) ( 147 )  
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    The oligomerization of butene is one of important process in chemical and oil refining industries. Its products are important chemical raw materials. Liquid isobutene oligomerization is investigated in a batch autoclave. The ionic liquid (C2H5)3NHCl-FeCl3 (mole fraction of FeCl3 is more than or equal to 0.55) shows good catalytic performance for the oligomerization of isobutene. Under good operating conditions, conversion of isobutene is above 85%, and the total mass content of dimers and trimers in oligomers is above 80%. Addition of CuCl in the ionic liquid can increase both isobutene conversion and the selectivity of dimers and trimers. When the mole ratio of CuCl to[(C2H5)3NH] Cl-0.6FeCl3 is 0.25, the mass content of dimers and trimers in oligomers reach up to 90.20% and conversion of isobutene is 98%.

    Catalytic performance of phosphotungstic acid encapsulated into MIL-101 for oxidative desulfurization with oxygen
    DING Jianwei, YU Meiqing
    2016, 67(S1):  283-288.  doi:10.11949/j.issn.0438-1157.20160577
    Abstract ( 89 )   PDF (1131KB) ( 207 )  
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    A heterogeneous catalyst, chromium terephthalate metal organic framework (MIL-101) encapsulated phosphotungstic acid (HPW), HPW@MIL-101,was prepared by one step method. And then it was used as catalyst in oxidative desulfurization system in which O2 acted as oxidant for the removal of dibenzothiophene (DBT). The effects of oxygen flow rate, sulfur content and reaction temperature on the desulfurization were studied. The results show that the DBT conversion is up to 74% for 60 min under the optimal reaction condition (sulfur content:350 μg·g-1, oxygen flow rate:90 ml·min-1, the amount of catalyst:1% the mass of normal octane; reaction temperature:75℃). The DBT conversion doesn't decrease obviously, after reused for three times with this catalyst. And it is possible to use air as green oxidant in desulfurization.

    Conditions and process of pervaporation benzene/cyclohexane mixture by waterborne polyurethane membranes
    YAO Lulu, YE Hui, SONG Ying, CUI Peng
    2016, 67(S1):  289-295.  doi:10.11949/j.issn.0438-1157.20151807
    Abstract ( 72 )   PDF (1021KB) ( 177 )  
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    The waterborne polyurethane membrane was synthesized with poly-1,4-butylene adipate glycol (PBA-2000) and toluene diisocyanate (TDI) and the properties of pervaporation benzene/cyclohexane mixture were tested to study the mass transfer characteristics during pervaporation process. From experimental data it can be concluded that the separation factor and flux should get bigger and smaller obviously as the membrane is very thin. And the variation of separation factor and flux was slight as the membrane thickness was certain thick. The improvement of downstream vacuum of the membrane should improve both the separation factor and flux. The bigger feed concentration and temperature should increase the flux and decrease the separation factor. The components in the pervaporation membrane should undergo the course of adsorbing swelling-evaporation in membrane-gaseous diffusion. The dry region of the membrane plays more effect during the pervaporation process.

    Influence of Al3+, Na+ and Mg2+ on crystallization of calcium sulfate dihydrate
    LIU Tonghai, DOU Yan, FANG Yang, CUI Peng, SHEN Hao, ZHENG Zhiyin, LIU Rong
    2016, 67(S1):  296-301.  doi:10.11949/j.issn.0438-1157.20151808
    Abstract ( 119 )   PDF (2513KB) ( 315 )  
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    The system, including CaHPO4·2H2O-H2SO4-H3PO4-H2O, is utilized to simulate wet process for phosphoric acid production. Based upon the slurry composition of phosphate mineral analysis, according to single factor experimental demands, the influence of Al3+, Na+and Mg2+ on crystallization and washing rate of CaSO4·2H2O were investigated. The result indicated that, it is beneficial for the size of CaSO4·2H2O crystals when adding Al3+into the system. Na+as the form of 0.9% (mass) Na2O in the slurry also caused agglomeration of CaSO4·2H2O crystals. We also found that it is helpful for the washing rate. But when Mg2+ was added into the system, the unfavorable impact such as increasing the viscosity of solution, seriously influencing crystal growth and washing rate. For our target production, CaSO4·2H2O crystal, XRD, SEM were adopted to characterize the products during the process. The results showed that crystal growth conforms to Burton-Cabrera-Frank model. The impurity ions change the reaction rate and crystal plane growth rate.

    Desulfurization performance of heteropolyacid with functionalized ionic liquids as solvents
    MA Yunqian, YU Meiqing
    2016, 67(S1):  302-306.  doi:10.11949/j.issn.0438-1157.20160600
    Abstract ( 75 )   PDF (967KB) ( 149 )  
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    Five kinds of functionalized ionic liquids ([CPL] [TBAB],[CPL]BF4,[Bmim]HCO3,[Bmim]OAc and[Bmim]Im) were synthetized, as well as heteropolyacid-ionic liquids ([CPL]3PMo12O40 and[Bmim]3PMo12O40) which have the same cations. Wet desulfurization by heteropolyacid is established. The desulfurization performance of the selected optimal desulfurizer is investigated at different absorption temperature and gas flow. The results show that [Bmim]3 PMo12O40-[Bmim]HCO3 has large capacity on desulfurization, and the optimal absorption conditions are over 40℃ and gas flow of 100 ml·min-1.[Bmim]3PMo12O40-[Bmim]HCO3 can be simply regenerated by air.

    Application of exergy destruction minimization in convective heat transfer optimization for elliptical tube
    WANG Junbo, XIE Pan, LIU Zhichun, LIU Wei
    2016, 67(S1):  307-311.  doi:10.11949/j.issn.0438-1157.20160544
    Abstract ( 74 )   PDF (2740KB) ( 343 )  
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    The expression of local exergy destruction rate is deduced on the analysis of convective heat transfer. Lagrange function is constructed with local exergy destruction rate set as optimization objective and prescribe flow power consumption as constraint condition. Besides, energy and mass conservation laws are taken into consideration in this Lagrange function. By taking variation on the Lagrange function, optimization equations are obtained. Through numerical simulation, the optimization equations are solved in the convective heat transfer for elliptical tube flow and the optimized velocity and temperature fields are obtained. The results show that the optimum flow structure in the elliptical tube is longitudinal swirl flow with multi-vortexes. Compared with the elliptical tube with general governing equations (Navier-Stokes equations), the optimized flow has a good heat transfer rate with low increase of flow resistance and the comprehensive performance, (Nu/Nus)/(f/fs), is 3.21. Furthermore, the distribution of vortexes in the elliptical tube is also obtained which is significant to improve the design of elliptical tubes.

    Retrieval of particle size distribution based on TSVD method with constraints
    ZHANG Biao, XU Chuanlong, WANG Shimin
    2016, 67(S1):  312-317.  doi:10.11949/j.issn.0438-1157.20160525
    Abstract ( 56 )   PDF (1039KB) ( 152 )  
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    Particle size distribution is one of the most important parameters and technical indicators. It not only directly affects the performance and quality of the products, but also helps to reduce energy consumption, improve the environment and safeguard human health. In this paper, several common particle size distributions were retrieved by measuring the extinction values of different visible spectrums using total light scattering methods under independent model. Wherein the estimation values were calculated by the Anomalous Diffraction Approximation (ADA), and the measurement values were obtained by applying Mie theory. A novel inversion algorithm was proposed by using Truncated Singular Value Decomposition (TSVD) regularization combined with two constraints, the particle size distribution is non-negative and the integral of the particle size distribution is equal to 1. To demonstrate the advantage performance of the proposed algorithm, several numerical test cases were investigated. The retrieval results show that the improved TSVD algorithm has higher retrieval accuracy than the traditional TSVD algorithm in the absence of measurement errors, and the improved TSVD algorithm has better anti-noise performance than the traditional TSVD algorithm under different measurement errors. Thus this improved TSVD algorithm can be used as an effective method for retrieval of particle size distribution.

    Characteristics of steam dynamic system in different operating environment
    LI Jian, ZHANG Guolei, SHI Zhijun, YANG Longbin, MA Biao, ZENG Shuai, LI Zihao
    2016, 67(S1):  318-325.  doi:10.11949/j.issn.0438-1157.20160546
    Abstract ( 74 )   PDF (1379KB) ( 117 )  
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    Environmental temperature and pressure, which act as the operating condition of the steam power system, play an important role in the safety and economy of the whole system. The simulation model of a steam power system was established to analyze and discuss the characteristics of the system under different ambient temperature and pressure. The results show that auxiliary engine power, steam flow and fuel flow increase with the raise of environmental temperature. Also, auxiliary engine power, steam flow and fuel flow increase with the decline of environmental pressure.Moreover, a lower load of dynamic system leads to a greater proportion of auxiliary engine power.

    Dynamic characteristics simulation of steam supplying system in different steam charging ways
    MA Biao, LI Yanjun, GUO Jiamin, ZHANG Guolei, SONG Fuyuan, LI Jian, ZENG Shuai, ZHANG Xiaoyu
    2016, 67(S1):  326-333.  doi:10.11949/j.issn.0438-1157.20160528
    Abstract ( 64 )   PDF (1099KB) ( 110 )  
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    With steam supplying system as the object of the research, the mathematical models are based on the lumped parameter theory. The study has been carried out in two different charging ways. One of them is charging valve in Auto-Control and the other is bypass valve in Auto-Control. The simulation results show as follows.The time to complete three times charging and discharging is 76.3 seconds when bypass valve is in Auto-Control. The time to complete three times charging and discharging is 62.9 seconds when charging valve is in Auto-Control. 4.5 seconds have been saved for each charging when charging valve is in Auto-Control. The key parameters maintain relatively stable during the charging period in both charging ways. The main parameters have relatively larger fluctuations when the two valves are being switched on. But the main parameters are less than 0.2 MPa. In the same charging way,the fluctuation of drum pressure is less than the fluctuation of superheated steam pressure, and the fluctuation of superheated steam pressure is less than the fluctuation of steam supplying pipe pressure.

    Dynamic simulation of control for main steam pressure of marine steam power system
    ZENG Shuai, SHI Zhijun, WANG Peng, ZHANG Guolei, SUN Baozhi, QUE Chenyu, MA Biao, LI Jian
    2016, 67(S1):  334-340.  doi:10.11949/j.issn.0438-1157.20160435
    Abstract ( 83 )   PDF (1073KB) ( 192 )  
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    Considering the influence that the great fluctuation amplitude and stabilization time of the main steam pressure, a comprehensive control method combining implicit GPC and PID was proposed. The model of the steam power system were built, including supercharged boiler, main steam turbine and condenser. The simulation system was validated through the experimental data. The simulation test was took on the models with the PID-GPC implicit algorithm. The results shows that the control strategy of the PID-GPC implicit algorithm makes up for deficiencies of the poor initial response of implicit GPC, reduces the fluctuation amplitude of the main steam pressure during the dynamic process, shorten the settling time.

    Anodic behavior of Fe in acidic AlCl3-EMIC ionic liquid
    YANG Yang, XUE Dongpeng, LING Guoping
    2016, 67(S1):  341-346.  doi:10.11949/j.issn.0438-1157.20151753
    Abstract ( 68 )   PDF (3850KB) ( 194 )  
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    The anodic behavior of Fe in 2:1 acidic AlCl3-1-ethyl-3-methyl-imidazolium chloride (AlCl3-EMIC) ionic liquid was investigated in this paper. Anodic polarization and chronoamperometry was measured using three-electrode system. The valence state of dissolved Fe was calculated by potentiostatic process. The surface morphologies of Fe were characterized using a scanning electron microscopy (SEM). The results showed that the oxide film would restrain the dissolution of Fe. After the oxide film was removed, Fe began to dissolve at the potential of -0.35 V versus Pt. The anodic current density increased rapidly to a maximum with the positive shift of potential and than decreased abruptly. The product existed in the form of Fe(Ⅱ). After galvanostatic process at 2 mA·cm-2, the surface of Fe showed a pitting morphology, which became homogeneous as time prolonged. With a larger anodic current applied (15 mA·cm-2), no obvious corrosion occurred on the surface of Fe electrode with precipitate formed.

    Effect of components of ionic liquids on oxidation desulfurization performance of hydrogen sulfur
    HU Jinchao, GAO Lixia, LIU Weihai, ZHAO Yonglu, GAO Shang, PAN Xingpeng, GUO Zhihui, YU Jiang
    2016, 67(S1):  347-352.  doi:10.11949/j.issn.0438-1157.20151736
    Abstract ( 94 )   PDF (1039KB) ( 202 )  
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    Based on the natural feature of Fe-based ionic liquids (Fe-IL), non-aqueous wet oxidation desulfurization of hydrogen sulfide was proposed in our preliminary work. But it has the poor gas-liquid mass transfer and low concentration of active Fe(Ⅲ), which leads the desulfurizing agent to be inactivated easily, and presents lower sulfur capacity and regeneration rate during the desulfurizing process. In this work, Fe-IL was used as bulk solution, Zn-based ionic liquids(Zn-IL), Mn-based ionic liquids(Mn-IL) and 1,3-dimethyl ketone of imidazoline (DMI) are selected as additives with different mass ration to construct complex ionic liquids to improve desulfuring performance. According to the results, the complex ionic liquids with bimetal show much better desulfuring performance, and a stronger intensified effect of DMI on improvement of desulfuring performance is observed after the introduction of DMI into Fe-IL. Particularly, the ternary system of DMI and Zn-IL in Fe-IL presents the best desulfuration performance.

    Preparation and characterization of activated carbon from Alternanthera philoxeroides by K2CO3 activation
    CHEN Wenting, RAN Qicheng, CAI Xianzong, LI Xianfa, XU Jianrong
    2016, 67(S1):  353-358.  doi:10.11949/j.issn.0438-1157.20151656
    Abstract ( 107 )   PDF (4454KB) ( 362 )  
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    A series of activated carbons (ACs) were prepared from Alternanthera philoxeroides (AP) by K2CO3 one-step mixing activation. The effects of various process parameters, such as mixing mass ratio of K2CO3 to AP, activation temperature and period, on the adsorptive property and the yield of AC were investigated. The surface morphology of AC were characterized with scanning electron microscopy (SEM). The results indicate that the optimized activation conditions were 1.5 of K2CO3 to AP mixing mass ratio, 800℃ of activation temperature, 3.0 h of the activation time. The yield, iodine number and methylene blue (MB) number of AC were 13.79%, 1477 mg·g-1, 384 mg·g-1, respectively. The recovery ratios of K2CO3 were over 80% when the nitrogen flow rate was no more than 100 ml·min-1. The SEM images of the ACs showed that the activation temperature has obvious effect on the porous structure.

    Multiple physical modeling for damage mechanism of high energy laser weapon
    SONG Naiqiu, ZHANG Haochun, MAO Chao, ZHAO Yang, WEI Yanqiang
    2016, 67(S1):  359-365.  doi:10.11949/j.issn.0438-1157.20160612
    Abstract ( 116 )   PDF (1147KB) ( 345 )  
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    The research on damage mechanism of high energy laser weapon is the basis for evaluating the damage effect. Based on the damage mechanism of the high-energy laser weapon, effect of thermal damage, mechanical damage and radiation damage by laser irradiation were investigated. Considering the surface state of different materials under laser irradiation, two models as steady state and unsteady state were established respectively. Moreover, numerical simulation was performed to evaluate the influence of tangential flow. In addition, the energy utilization efficiency of laser irradiation was discussed, and the effect of different materials on the laser protection was also compared. The results of the current can provide theoretical basis for laser damage assessment.

    Nondestructive evaluation of insulation condition of transformer bushings based on degree of polymerization of oil-paper
    SUN Changhai, LI Weijiang, WANG Ming, CHEN Baitong, WU Yan, ZHONG Juntao, XUE Jingmei, PENG Na, WEN Zheng
    2016, 67(S1):  366-371.  doi:10.11949/j.issn.0438-1157.20160240
    Abstract ( 78 )   PDF (1640KB) ( 228 )  
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    The paper is to study the relationship between degree of polymerization (DP) of oil-paper and frequency domain dielectric spectroscopy (FDS) in the insulation assessment of oil-paper condenser bushings. To achieve the result, a sample of oil-paper condenser bushings was designed and tested in aging. Through the measurement of DP and FDS of different aged samples and the study of relationship between DP and frequency domain curve of capacitance (C)and dielectric loss factor (tan δ),a new method of insulation assessment of oil-paper condenser bushings was invented. The results show that:(1) the capacitance frequency domain dielectric characteristic quantity of the oil-paper insulation sample in 10-3-1 Hz can reflect the aging status of bushing;(2) There is a secondary polynomial function between DP and frequency domain curve of C;(3) The dielectric loss factor reflects the aging status of bushing only in the 1 Hz.

    Preparation and properties of nano composite phase change thermal storage materials
    KANG Yameng, DIAO Yanhua, ZHAO Yaohua, WANG Shun
    2016, 67(S1):  372-378.  doi:10.11949/j.issn.0438-1157.20160619
    Abstract ( 138 )   PDF (2165KB) ( 288 )  
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    Phase change materials(PCMs) is the basis of the research of phase change heat storage technology. Aimed at the low thermal conductivity of common phase change material-paraffin, nano particles addition technology was used to enhance the heat transfer performance of paraffin, so the thermal conductivity and thermal diffusion coefficient of paraffin were improved. Through melting test of nano particle-paraffin and observation of settling process of nano particles, Cu nanoparticle and dispersing agent Hitenol BC-10 were selected to prepare a kind of stable nano-particle/paraffin composite phase change storage material, and its thermal physical properties were tested. The experimental results showed that addition of nano-copper particles could increase the thermal conductivity of paraffin apparently. Compared with the pure paraffin, thermal conductivity of solid nano-copper/paraffin increased by 7.9%, the liquid nano-copper/paraffin increased by 3.8%, while the solid and liquid thermal diffusion coefficient increased by 20.6% and 16% respectively.

    Synthesis of SiO2 nanoparticles by chemical precipitation
    HU Yanwei, CHENG Gong, LI Haoran, HE Yurong
    2016, 67(S1):  379-383.  doi:10.11949/j.issn.0438-1157.20160565
    Abstract ( 164 )   PDF (1660KB) ( 586 )  
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    With excellent physical characteristics such as heat proof, thermal insulation and abrasion resistance, etc., silica nanoparticles have attracted a lot interesting from various industries. Many methods have been proposed to formulate SiO2 nanoparticles, for example, aerosol method, chemical precipitation method, microemulsion method and sol-gel method. Compared with other methods, chemical precipitation uses cheaper materials and is easily to be industrialized. In present work, based on the chemical precipitation method, SiO2 nanoparticles were prepared using sodium silicate (Na2SiO3) as silicon source, ammonium chloride (NH4Cl) as precipitant and cetyl trimethyl ammonium bromide (CTAB) as dispersant. TG-DSC was used to determine the decomposition temperature of CTAB. After the preparation, SiO2 nanoparticles were characterized using Fourier Transform Infrared Spectrometer (FTIR Spectrometer), X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Results show that SiO2 nanoparticles formulated by chemical precipitation were amorphous state with an average diameter of 80 nm.

    Preparation of proton exchange membrane by radiation-induced grafting of PVDF film
    GAO Jinjin, LI Xue, ZHAO Yubin, LI Weiwei, ZHAO Yang, WANG Shubo, XIE Xiaofeng, ZHANG Zhenlin
    2016, 67(S1):  384-389.  doi:10.11949/j.issn.0438-1157.20160654
    Abstract ( 93 )   PDF (1066KB) ( 328 )  
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    Sulfonated proton exchange membrane is a kind of ion exchange membrane with high thermal stability, chemical stability and good mechanical properties, having extremely broad application prospects. Numerous free radicals can be generated when the poly(vinylidene fluoride)(PVDF) membrane was irradiated by 60Co γ-source, acting as active sites for the graft of 4-sulfonyl chloride vinylbenzene monomer, thus the proton exchange membrane can be prepared by subsequent alkaline and acid treatment. And the structures of the monomer, the original PVDF and grafted PVDF membrane were confirmed by FT-IR spectra, indicating that the monomer had been successfully grafted into PVDF membrane. This proton exchange membrane shows good thermal stability, also can meet the requirement of the temperature of proton exchange membrane fuel cells. The relationship of the proton conductivity, water uptake, ionic exchange capacity with degree of graft at different does rate but same total does were studied. The results showed that when the does rate was 40 Gy·min-1, the degree of graft of the membrane was 52.7%, ionic exchange capacity was 1.274 mmol·g-1, water uptake was 36.85% and conductivity was 136 mS·cm-1 at 80℃.

    Synthesis, characterization, simulation of 4-styrenesulfonyl chloride and its application in preparation of proton exchange membrane through radiation induced grafting
    LI Xue, ZHAO Yang, GAO Jinjin, LI Weiwei, WANG Shubo, XIE Xiaofeng
    2016, 67(S1):  390-395.  doi:10.11949/j.issn.0438-1157.20160710
    Abstract ( 92 )   PDF (1694KB) ( 181 )  
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    4-Styrenesulfonyl chloride was synthesized successfully and characterized by FTIR,1H NMR and 13C NMR spectra. Quantum chemistry calculation based on density functional theory was carried out for this synthesized monomer, and the Mulliken population analysis showed that 4-styrenesulfonyl chloride possess comparative charge distribution to styrene, which is commonly used as graft monomer in the preparation of proton exchange membrane, indicating that 4-styrenesulfonyl chloride is possible to be used as graft monomer. Fukui function of 4-styrenesulfonyl chloride declared that the alpha carbon of the vinyl is susceptible to electrophilic attack while the beta carbon showed higher reactivity with respect to nucleophilic and radical attack. Radiation induced graft polymerization of 4-styrenesulfonyl chloride on to FEP film was taken under 60Co gamma rays. After hydrolysis with KOH, H2SO4 solution and rinsing by deionized water to neutral, the membrane turned into proton conductive. The conductivities of these membrane are in accordance with the graft yield and increase with temperature. Conductivity of the membrane with does rate of 20 Gy·min-1 reached 84.56 m S·cm-1 at 348 K.

    One-step synthesis of stable hydrosoluble dispersion of reduced graphene oxide in presence of poly (sodium 4-styrenesulfonate)
    HAN Xiaodong, ZHAO Zhiwei, LI Xuehua, SHI Chenyan
    2016, 67(S1):  396-401.  doi:10.11949/j.issn.0438-1157.20160657
    Abstract ( 155 )   PDF (3555KB) ( 211 )  
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    With the aid of poly(sodium 4-styrenesulfonate) (PSS), a facile one-step method of producing stable hydrosoluble dispersion of reduced graphene oxide is reported. The prepared dispersion was very stable and no aggregation or precipitation was observed for several weeks. The obtained nanosheets were characterized by various diagnostic techniques. The results by scanning electron microscopy (SEM) and UV-Vis spectrum showed that PSS was tightly attached to the reduced graphene oxide and the hydrophilicity of graphene was greatly improved. Fourier transform infrared spectroscopy (FTIR) spectrum indicated the existence of O=S=O groups in PSS. X-Ray photoelectron spectroscopy (XPS) spectrum provided further evidence about the C/S atomic ratio and sulfur-bonded carbon atoms from PSS. The results shown in this study proved that this PSS-coated reduced graphene oxide could be implemented in graphene-based composites.