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30 May 2014, Volume 65 Issue S1
    CIESC Journal(HUAGONG XUEBAO)Vol.65 No.S1 May 2014
    2014, 65(S1):  0-0. 
    Abstract ( 226 )   PDF (1531KB) ( 187 )  
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    Characteristics of evaporative surface of micro wick structures in heat pipes
    CHEN Qiang, HUANG Yonghua
    2014, 65(S1):  1-4.  doi:10.3969/j.issn.0438-1157.2014.z1.001
    Abstract ( 668 )   PDF (1288KB) ( 230 )  
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    Three-dimensional numerical simulation on the evaporative surface of the micro wick structures in heat pipes was conducted using interfacial tension theory and surface discrete method. The micro menisci caused by wetting were discretized with triangle-based mesh. Following the principle of minimizing free energy, the thermodynamic equilibrium status was then determined by moving mesh nodes. The behaviors of capillary force, total evaporation area, and thin-film area, etc. were studied systematically with different geometric parameters and contact angles.
    Impact of contact force on thermal transport at a point contact
    WANG Jianli, BAO Jiajian, DONG Mei, ZHAO Weiwei, YANG Juekuan, NI Zhonghua, CHEN Yunfei
    2014, 65(S1):  5-10.  doi:10.3969/j.issn.0438-1157.2014.z1.002
    Abstract ( 39 )   PDF (1379KB) ( 200 )  
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    The thermal contact resistance plays an important role in heat transport in the applications such as nuclear reactor, thermoelectric devices, electronic cooling system, etc. To investigate the thermal transport at nanosized point contact, a structure is established by pressing two microwires crosswise against each other, and the theoretical expression based on the present model is deduced. Combined with the surface topography obtained by the atomic force microscopy (AFM), the impact of the contact force on the thermal contact resistance and electrical contact resistance is investigated. The experimental results show that, if the relative displacement between the two microwires is smaller than 5 μm, the corresponding contact force is calculated to be less than 10-7N, and the relationship between the thermal contact resistance and electrical contact resistance agrees approximately well with that predicted by the Wiedemann-Franz law. As the displacement increases, the measured thermal contact resistance has a sharp decrease, then remains nearly unchanged. In that case, the thermal contact resistance is about an order of magnitude smaller than the initial data, and the electrical resistance is displacement-independent, making the thermal contact resistance much larger than the theoretically predicted value, and the Lorenz number ranges from 4 to 5×10-8 W·Ω·K-2, which is possibly due to the insulating layer covered on the microwires. The AFM images illustrate that the surface roughness ranges from tens to hundreds nanometers, making the significant change in the absolute value of the thermal contact resistance in different experiments.
    PIV experiment on turbulence characteristic with different winglets inserted
    CHE Cuicui, TIAN Maocheng, LENG Xueli, TANG Yufeng
    2014, 65(S1):  11-16.  doi:10.3969/j.issn.0438-1157.2014.z1.003
    Abstract ( 431 )   PDF (4166KB) ( 260 )  
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    The velocity fields in the circular tube with trapezoid-winglets inserted were investigated by particle image velocimetry (PIV) technique and the turbulent characteristics induced by different arrangement winglets were also compared. The results showed that swirling flow induced by the up-flow winglets extent along the radial direction and had greater intensity as well as better persistence. Inside vortex pair the flow was to the wall direction while outer vortex pair the flow was away from the tube wall, which flow pattern was inversed for the down-flow winglets. In addition, the swirling flow induced by down-flow winglets extent more along the circumference direction and the disturbance effect was obvious in a short distance downstream the winglets. Both swirling flow patterns could disturb the near wall region flow, destroying the velocity boundary layer and notably improving the velocity component normal to the mainstream, which lead to the intensification of the transverse mixing action and mass transfer in the tube. As the Reynolds number increasing, the dissipative interaction between the two flow layers was enhanced, decreasing the stability of longitudinal vortex. In a certain range of Reynolds numbers involved in the experiment, it could be drawn that both arrangement winglets showed better disturbance effect when Re=3000.
    Turbulent flow characteristics of nanofluids inside circular tube
    WANG Peng, BAI Minli, LÜ Jizu, HU Chengzhi, WANG Yuyan
    2014, 65(S1):  17-26.  doi:10.3969/j.issn.0438-1157.2014.z1.004
    Abstract ( 861 )   PDF (7734KB) ( 296 )  
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    The current study explained the mechanism of heat transfer enhancement of nanofluids from the micro-flow aspect. The Eulerian-Eulerian and Euler-Lagrange multiphase models are implemented respectively to explore the flow field of nanofluids inside a horizontal circular tube under turbulent state.The pressure loss is used to validate the accuracy of predictions for each model, which is the most important flow parameter in turbulent flow but also is frequently ignored in previous numerical work.The results indicated that there is obvious velocity slip phenomenon between water and nanoparticles.Compared with the pure water, the development of nanofluids boundary layer is inevitably disturbed, which consequently decreases its thickness and thermal resistance.The distribution of nanoparticles in the entire flow field is not uniform, which improves overall heat transfer capacity inside the boundary layer. The present authors suggest the enhanced heat transfer capability of nanofluids is the result of altered flow characteristics when nanoparticles are present and the flow conditions are most important drivers of heat transfer enhancement in nanofluids. The thorough understanding on flow characteristics of nanofluids is essential for nanofluids flow, which is the basis of further utilization of nanofluids in engineering applications.
    Coupled heat and moisture in hollow fiber membrane tube bank used for desiccant regeneration in liquid desiccant air dehumidification process
    HUANG Simin, CHEN Baiman, YANG Minlin, XIAO Hanmin
    2014, 65(S1):  27-31.  doi:10.3969/j.issn.0438-1157.2014.z1.005
    Abstract ( 394 )   PDF (591KB) ( 191 )  
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    The coupled heat and moisture transfer in a counter flow hollow fiber membrane tube bank used for liquid desiccant regeneration are investigated. Two fibers, the solution stream inside the fibers, and the air stream surrounding the fibers are selected as the calculating domain. The partial differential equations governing the fluid flow and heat mass transports are established and solved by a controlled volume method and a body-fitted transform technology. The friction factor, Nusselt and Sherwood numbers in the unit cells during the desiccant regeneration process are obtained and analyzed. These fundamental data for the uniform temperature and heat flux boundary conditions are compared. The features of the heat and moisture transports for the solution regeneration are disclosed.
    Numerical simulation of thermoacoustic waves in square cavity filled with water
    ZHAN Liyuan, LI Yuhua, JIANG Yuyan, WANG Gang, TANG Dawei
    2014, 65(S1):  32-38.  doi:10.3969/j.issn.0438-1157.2014.z1.006
    Abstract ( 428 )   PDF (2142KB) ( 230 )  
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    The generation and propagation of thermoacoustic waves in a water-filled square cavity is numerically studied in order to investigate the effects of them on the heat transfer at the boundary. In all cases considered, the left wall of the cavity is rapidly heated with different heating methods to generate thermoacoustic waves. The results show that the amplitudes of pressure and heat flux waves at the middle point of the right wall in water are much larger than that in air under the same boundary conditions. The value of pressure and heat flux increases sharply with the overheat ratio. Under the constant heat flux boundary condition, the pressure average in water is higher, but the heat flux is lower than that in air during the computation.
    Frequency analysis and amplitude characteristics of pressure oscillation for steam jet
    QIU Binbin, ZHAO Quanbin, ZHAO Weiyue, YAN Junjie, LIU Jiping
    2014, 65(S1):  39-43.  doi:10.3969/j.issn.0438-1157.2014.z1.007
    Abstract ( 395 )   PDF (1745KB) ( 246 )  
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    Experimental investigation on pressure oscillation characteristics for steam jet have been performed in steam mass flux 298-865 kg·m-2·s-1, water temperature 20-70℃. The dominant frequency agreed with the periodic ballooning and contraction of steam plume. The dominant frequency first increased and then decreased with the increasing water temperature for the condensation region transforming from condensation oscillation region to stable condensation region. The dominant frequency decreased with the increasing water temperature. The variation of dominant frequency was opposite to that of amplitude. Based on the experimental data and analysis, a correlation was given to predict the dimensionless root mean square amplitude. The prediction error was within ±30% in steam mass flux 370-865 kg·m-2·s-1, water temperature 20-60℃.
    Interface-capturing method on quadtree-based adaptive Cartesian grid
    WANG Shenghui, YOU Wei, LI Zengyao
    2014, 65(S1):  44-50.  doi:10.3969/j.issn.0438-1157.2014.z1.008
    Abstract ( 368 )   PDF (2765KB) ( 219 )  
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    Capturing the moving ingerface is one of the critical issues in the simulation of two-phase flows. In this paper, a moving interface capturing method based on the level set method and the quadtree grid is preseated, in which the grid is locally and self-adaptively controlled. It is validated from three moving interface problems with the given velocity field of translational flow, rotational flow and shear flow that the combination of the Level set method and the quadtree grid is more efficient and accurate.
    Boundary element analysis of heat conduction problems in anisotropic media with variable coefficients
    GAO Xiaowei, ZHAO Jinjun, LIU Jian, HU Jinxiu
    2014, 65(S1):  51-60.  doi:10.3969/j.issn.0438-1157.2014.z1.009
    Abstract ( 524 )   PDF (2141KB) ( 366 )  
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    A method for establishing fundamental solutions of general variable coefficient heat conduction problems in anisotropic media using the boundary element method was presented. The pure boundary integral equation is derived for solving general two- and three- dimensional steady heat conduction problems in anisotropic media. The established fundamental solutions are suitable for the situation that the thermal conductivity is a function of spatial coordinates, and therefore the developed integral equation can be used to solve the heterogeneous material heat transfer problems. The domain integrals induced by heat sources can be transformed into a boundary integral using the radial integral method, so a pure boundary element method which does not need any interior points is formed. Three examples for two- and three- dimensional problems are provided and the correctness and effectiveness of the proposed method is validated by comparing the results using the current method with that of using finite element method.
    Energy effectiveness analysis of countercurrent humidifier
    XIE Yingchun, MEI Ning
    2014, 65(S1):  61-65.  doi:10.3969/j.issn.0438-1157.2014.z1.010
    Abstract ( 661 )   PDF (1248KB) ( 328 )  
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    In this paper, the ε-NTU function of direct contact devices based on modified energy effectiveness definition was verified by 75 groups of countercurrent humidifier experimental data. The affection of pressure, water/air mass flow ratio, inlet water temperature and inlet air wet bulb temperature on heat capacity rate ratio and energy effectiveness were analyzed. The results show maximum relative-error of modified ε-NTU function is 27.7%, which can be used in engineering calculation. Heat capacity rate ratio change monotonically increase or decrease with operation parameters, while energy effectiveness curves has minimum inflection point at heat capacity flow being equal to 1. At fixed operating pressure, the affection of inlet air wet bulb temperature, water/air mass flow ratio and inlet water temperature on energy effectiveness of countercurrent humidifier decreases in turn.
    Natural convection of water near its density maximum in cavity with complex geometry structure
    HU Yupeng, MO Dongming, LI Yourong
    2014, 65(S1):  66-72.  doi:10.3969/j.issn.0438-1157.2014.z1.011
    Abstract ( 380 )   PDF (2902KB) ( 265 )  
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    A series of numerical simulations on natural convection of water near its density maximum in a cavity with complex geometry structure was performed using finite volume method. The flow and thermal fields and the variation law of local and average Nusselt on the wall with the Rayleigh number at different density inversion parameters were obtained. The results show that the effect of density inversion parameter on the flow structure and heat transfer characteristic is significant. The flow intensity becomes weak with the increase of the aspect ratio. Under the same conditions, the flow, thermal fields and heat transfer rates vary in degree with the geometry structure of the out wall changes.
    Strengthen absorption mechanism research on aqua ammonia falling film absorption based on transversally grooved tube
    CHEN Xiaozhuan, WEN Xiaoping, SHENG Wei, ZHANG Anchao, LIU Jianhua
    2014, 65(S1):  73-78.  doi:10.3969/j.issn.0438-1157.2014.z1.012
    Abstract ( 525 )   PDF (1447KB) ( 291 )  
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    On the basis of laminar and turbulent theory, mathematical model was presented about aqua ammonia falling film absorption performance, and theoretical formula of ammonia absorption rate for aqua ammonia was deduced. This formula indicated two methods which can improve ammonia absorption rate, namely sprinkle density of aqua ammonia outside tube and ammonia solubility of aqua ammonia. When sprinkle density of aqua ammonia increased from 615 kg·m-1·h-1 to 3191 kg·m-1·h-1, ammonia absorption rate rose by 220%. In winter the aqua ammonia absorption experiments using 2# tube were carried out under absorption pressure of 0.15 MPa. When average temperature of aqua ammonia increased from 25℃ to 34℃, ammonia absorption rate decreased by 130%.In summer the aqua ammonia absorption experiments using 2# tube were carried out under absorption pressure of 0.25 MPa. When average temperature of aqua ammonia increased from 35℃ to 50℃, ammonia absorption rate decreased by 86%.An important parameter having influence on transversally grooved tube (TGT) falling film absorption performance is comprehensive impact factor of groove size i.e.e2/pd. Choosing this comprehensive impactfactor and falling film Reynolds number as independent variable, the correlation equation of Sherwood number was established for ammonia solution falling film absorption outside tube.
    Jet flow phenomenon during subcooled nucleate boiling of self-rewetting fluid
    ZHOU Leping, LI Yuanyuan, WEI Longting, DU Xiaoze, WANG Buxuan
    2014, 65(S1):  79-84.  doi:10.3969/j.issn.0438-1157.2014.z1.013
    Abstract ( 482 )   PDF (4077KB) ( 248 )  
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    In this paper, a self-rewetting fluid, namely aqueous n-butanol solution, is employed for demonstrating the thermocapillary effect on bubble behaviors during subcooled nucleate boiling on thin wire by comparing with deionized water. Bubble-top jet flow for these fluids is observed around a platinum micro heated wire by high speed CCD camera. Corresponding numerical simulation proves that it is the thermocapillary convection that attracts the subcooled water to flow from the superheated microlayer at the base to the top of a stationary bubble. For n-butanol solution, however, the thermocapillary convection can induce it to flow oppositely, which causes the subcooled solution to flow onto the heated surface. The simulation for the solution is in good agreement with the experiment where the subcooled liquid near the bubble top flow towards the bubble base and hence multi-jet flows occur. The multi-jet flows can sustain for a long period and cause transient chaos at the superheated thin liquid layer near the heated surface. The temperature around the bubble presents sharp temperature gradient and the velocity in the near wall regionis almost vertical to the wall. The studies on the effect of thermocapillary convection are crucial to the mechanisms of subcooled nucleate boiling of fluids.
    Numerical simulation on flow and heat transfer characteristics in shell side of outward convex corrugated double-pipe heat exchangers
    HAN Huaizhi, LI Bingxi, HE Yurong, SHAO Wei
    2014, 65(S1):  85-94.  doi:10.3969/j.issn.0438-1157.2014.z1.014
    Abstract ( 778 )   PDF (3625KB) ( 423 )  
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    The flow and heat transfer mechanism in the shell side of corrugated double-pipe heat exchanger are studied numerically based on the k-ε model. The independent analysis of first layer thickness and main flow region grid are carried out using hexahedral mesh in the whole region combined with dense mesh in the corrugation region. Compared the data from empirical formula with computational results, the accuracy of numerical methods is verified. The strengthening heat transfer mechanism is revealed by analyzing the difference of the flow and heat transfer parameters distribution (speed, temperature and turbulent kinetic energy and turbulence dissipation rate) between corrugated tube and smooth tube. Meanwhile, the local Nusselt numbers and pressure drop distributed law along the corrugation wall is also analyzed. The results indicate that the detached vortex formed at the downstream side of corrugation which resulting in an obvious effect of heat transfer augmentation destroys the velocity and temperature boundary layer meanwhile increase the frictional resistance and thermal diffusivity.
    Visualized experiment of melting of paraffin wax in aluminum foam with open cells
    GAO Dongyan, CHEN Zhenqian, CHEN Linghai
    2014, 65(S1):  95-100.  doi:10.3969/j.issn.0438-1157.2014.z1.015
    Abstract ( 526 )   PDF (1990KB) ( 221 )  
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    The visualized experiments of melting of paraffin wax in open-cell aluminum foam are performed using the microscopical technique and the infrared camera. The phase change process of paraffin wax and fluid flow are revealed in aluminum foam at the pore level, and the thermal performance of the paraffin-aluminum foam composite is visually investigated. The experimental results indicate that the aluminum foam can helpfully enhance phase change heat transfer of paraffin wax, and the wax-aluminum foam composite mainly dominated by the conduction of metal matrix has better thermal performance than the pure wax with clearly melting interface. In addition, several fragments of suspended matters are observed to be existed in the liquid wax.
    Heat transfer characteristics of clathrate hydrate slurry in horizontal mini-tubes
    ZHANG Peng, YE Jian, QIAN Wenqiang
    2014, 65(S1):  101-105.  doi:10.3969/j.issn.0438-1157.2014.z1.016
    Abstract ( 658 )   PDF (2354KB) ( 357 )  
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    The heat transfer characteristics of tatra-n-butyl ammonium bromide(TBAB)clathrate hydrate slurry (CHS) flowing through the heated mini-tubes under constant heat flux are investigated in the present paper. The inlet and outlet temperature, outer tube wall temperature and flow velocity of TBAB CHS in heated tube were measured. The variation of the temperature along the tube was obtained by solving the continuity, momentum and energy equations. It was found that influence of heating flux on heat transfer was larger in smaller tube. In addition, influence of flow velocity in laminar region is smaller than that in turbulence region. Referring to the results of ice slurry and MPCM slurry, a similar form is adopted to fit experimental data. The empirical heat transfer correlation are quantitatively similar to those of experimental results and the relative errors are within ±20%.
    Experimental analysis of heat transfer performance of thermal insulated tubing for steam injection in wellbore
    WANG Zhiguo, SONG Mingqi, ZHANG Xin, JIA Yongying, XIANG Xinyao
    2014, 65(S1):  106-110.  doi:10.3969/j.issn.0438-1157.2014.z1.017
    Abstract ( 496 )   PDF (729KB) ( 204 )  
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    In the process of thermal recovery of heavy oil, hot fluid is injected into oil reservoir through pipe strings made up of thermal insulated tubing. Thermal insulated tubing is the key component to reduce heat loss and to protect tubes in the process of hot fluid injection. Currently the researches on heat loss of thermal insulated tubing by domestic and foreign scholars mainly focus on theoretical analysis and numerical calculation. Thermal insulated tubing consists of interior tube, thermal insulating layer and exterior tube, its thermal insulated effect depends on the apparent heat conductivity of thermal insulating layer. This paper designed and developed ground analogue test device of thermal insulated tubing and actually measured the surface temperature hot fluid distribution with device, then calculated the apparent heat conductivity of new and old thermal insulated layer based on experimental date. The study result shows that: heat bridge existed between the collar and exterior of insulated pipe, and the affected length of insulated pipe is about 0.5 m.Heat flow rate in the normal insulated pipe is less 3 times than that in the heat density of collar. The apparent hot flow, surface temperature and apparent heat conductivity of oldthermal insulated tubing is obviously higher than those of new thermal insulated tubing, and the thermal insulated performance in the old insulated tubing decreases. According with current manufacture technique and structure characteristics of thermal insulated tubing, some suggestions are proposed for improving thermal insulated performance.
    Numerical investigations of double diffusive mixed convection in enclosure
    XU Hongtao, XIAO Ruixue, YAN Zhenrong, SHAO Bin, YANG Mo
    2014, 65(S1):  111-118.  doi:10.3969/j.issn.0438-1157.2014.z1.018
    Abstract ( 468 )   PDF (2925KB) ( 234 )  
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    The double diffusive mixed convection around a heated cylinder in an enclosure was numerically studied. The heated cylinder was located at the center of the enclosure with high temperature and concentration. The inlet flow with low temperature and concentration was located at the lower-left wall of the enclosure and the exit was at the upper-right wall. First, the influences of Richardson number (Ri) on the interior flow characteristics were presented. It showed that the oscillation phenomenon occurred at Ri=0.001. At Ri=1.0, the flow was in a steady state. Then, the influences of Lewis number (Le) and buoyancy ratio (Br) on the double diffusive mixed convection were investigated while the Richardson number was kept constant at 1.0. The average Nusselt number Nuavand Sherwood number Shav were reported. The current study can provide the theoretical supports for the pollutant control, thermal comfort or smoke control in space.
    Condensation heat transfer of mixed R134a/R125 outside horizontal tubes
    ZHANG Dingcai, DU Jiadi, JI Wentao, ZHANG Zhen, ZHU Chunjie, HE Yaling, TAO Wenquan
    2014, 65(S1):  119-124.  doi:10.3969/j.issn.0438-1157.2014.z1.019
    Abstract ( 501 )   PDF (1911KB) ( 296 )  
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    Experimental studies of film condensation of R134a and mixed R134a/R125 at three different concentrations have been conducted on three tubes, one is smooth tube, the others are two-dimensional and three-dimensional enhanced tubes at the same fin density. The results indicate that the predicted condensation heat transfer coefficients of R134a on smooth tube from Nusselt theory agree with the experimental data within ±10 percent. The condensation heat transfer coefficients of pure R134a are consistent with Nusselt theoretical trend for smooth and enhanced tubes. Compared with pure R134a, the condensation heat transfer coefficients of mixed R134a/R125 are all decreased. For smooth tube, condensation heat transfer coefficient of mixed refrigerants decreased with the increase of temperature difference. But for enhanced tubes, condensation heat transfer coefficients increased with the increase of temperature difference, which is close to pure R134a at high temperature difference, the mixed refrigerant including 6 percent and more R125. Indicating that condensation heat transfer of mixed refrigerants is quite different with pure refrigerants. Condensation heat transfer coefficient of three-dimensional enhanced tube is higher than that of the two-dimensional tubes, and two-dimensional tube is significantly higher than that of smooth tube at the same working fluid. The condensation heat transfer enhancement factor of HT-3D, HT-2D are 9.83 and 7.85, respectively, which compared with smooth tube at the temperature difference 8 K.
    Calculation of vapor compression heat pump evaporator gravity-independent
    MA Rui, WU Yuting, LIU Gang, MA Chongfang
    2014, 65(S1):  125-129.  doi:10.3969/j.issn.0438-1157.2014.z1.020
    Abstract ( 378 )   PDF (1412KB) ( 179 )  
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    Vapor compression heat pump has a good prospect of application in high temperature environments and high-power spacecraft thermal control system. Aerospace vapor compression heat pump operates in the microgravity environment. Microgravity vapor compression heat pump adaptability is the key to a vapor compression heat pump technology aerospace research and development. The evaporator is a key component of the vapor compression heat pump.By calculating vapor compression heat pump evaporator to explore its gravity-independent conditions and get gravity-independent critical velocity and critical diameter at different evaporation temperatures and under different flow rates. The results showed that the minimum critical velocity in the evaporator gravity-independent region in 1.45-1.5 m·s-1. The maximum critical diameter increases with cooling capacity, and cooling capacity from 50 W to 300 W, the critical diameter from 0.42 mm to 1.02 mm.
    Dynamic characteristics of boiler-accumulator under condition of different steam charging and discharging
    YU Haitao, LI Yanjun, ZHANG Guolei, MA Hongbo
    2014, 65(S1):  130-137.  doi:10.3969/j.issn.0438-1157.2014.z1.021
    Abstract ( 493 )   PDF (3493KB) ( 212 )  
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    With boiler-steam accumulator system as the object of the research, the purpose of this paper is to investigate the dynamic characteristics of this system under two different conditions of steam charging and discharging by the way of combination between simulation and experiment, the mathematical models are based on the lumped parameter theory. The calculation results demonstrate that the established model can correctly reflect the dynamic characteristics of this system, and provide some references for the optimal design and safe operation of the system. Further analysis shows that the steam accumulator needs 57 s to charge steam from the lower limit to the upper limit of pressure in the continuous process of steam charging and discharging, but 67 s in the intermittent process, which is longer obviously. At the same time, for some using steam occasions of periodic intermittent or instant, the effect of the continuous steam charging and discharging is more significant in terms of eliminating large fluctuation of load in the steam boiler, stabilizing pressure, improving the efficiency of the boiler, etc.
    Heat transfer of thermal cracking and initiated cracking of aviation kerosene
    JIA Zhenjian, ZHOU Weixing, HUANG Hongyan, YU Wenli
    2014, 65(S1):  138-143.  doi:10.3969/j.issn.0438-1157.2014.z1.022
    Abstract ( 301 )   PDF (2043KB) ( 218 )  
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    Nitro-propane (NP) was employed as the initiator to investigate the effect of initiated cracking on heat transfer of aviation fuel RP-3 with a one-stage and cracking system operating under supercritical pressure. The pyrolysis products are analyzed using a chromatograph/mass spectrometry (GC-MS). The heat sink, conversion rate and heat transfer coefficient were calculated based on the experimental results. Experimental results indicate that the heat transfer characteristics are influenced by the pyrolysis rate and physical property change caused by products distribution. NP accelerates the pyrolysis and increases the heat sink of fuel in temperature range of 800 K to 900 K. Under the same heat flux conditions, the effects of NP are reflected in the reduction of fuel and wall temperature. The reductions of fuel and wall temperature increase first and decrease along the flow direction, and the maximum decrease is more than 10 K. However, the Reynolds numbers decrease because of large amount gaseous products generated by pyrolysis reaction, which has negative effect on the convective heat transfer. So the influence of initiated cracking on the heat transfer of RP-3 is not a simple effect of promotion or inhibition, the regularity is different in different temperature ranges.
    Heat transfer characteristics of evaporator with rectangular microgrooves under electric field
    GUO Lei, DIAO Yanhua, ZHAO Yaohua, LIU Yan, WANG Shun
    2014, 65(S1):  144-151.  doi:10.3969/j.issn.0438-1157.2014.z1.023
    Abstract ( 364 )   PDF (3825KB) ( 232 )  
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    The influence of electric field on the evaporation/boiling heat transfer characteristic for an evaporator with rectangular micro-channels was experimentally investigated. R141b was used as the working fluid. The cylindrical electrode was used to produce electric field. The experimental result indicates that heat transfer enhancement is strongly dependent on the electric field strength. The heat transfer enhancement increase with the increase of the electric field strength. Furthermore, operating pressure has a strong influence on the evaporation/boiling heat transfer enhancement when the electric field strength keeps constant. The maximum enhancement of heat transfer coefficient is 1.28 times.
    Wall temperature distribution characteristics of flow and heat transfer inside horizontal helically-coiled tube
    LU Guoqiang, HAN Jitian, KONG Lingjian, CHEN Changnian, JI Cuilian
    2014, 65(S1):  152-156.  doi:10.3969/j.issn.0438-1157.2014.z1.024
    Abstract ( 40 )   PDF (1029KB) ( 302 )  
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    Helically-coiled tube is a kind of high-efficiency heat transfer tube. When fluid flows in horizontal helically-coiled tube it will be affected by gravity and centrifugal forces, and the flow direction changes from time to time, resulting in secondary flow and thus behaving different flow and heat transfer characteristics from those in other tubes. In order to explore the temperature distribution characteristics of the inner tube wall when fluid flows in single phase and under subcooled boiling, the inner tube wall temperatures on the bottom, the rising part and the top cross sections selected in a horizontal helically-coiled tube are experimentally studied by means of increasing the heat flux gradually. Factors which result in these characteristics are explained in detail. The completed work has significance of reference for the design and engineering applications of helically-coiled tube heat exchangers.
    Thermal performance of electronic components based on phase change materials
    LAI Yanhua, WU Tao, WEI Lulu, DONG Zhen, LÜ Mingxin
    2014, 65(S1):  157-161.  doi:10.3969/j.issn.0438-1157.2014.z1.025
    Abstract ( 361 )   PDF (2433KB) ( 587 )  
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    A comparison was made among the thermal manage performance of electronic components based on radiator with three different kinds of material filling state, without paraffin, pure paraffin, composite of graphite with paraffin. The surface temperature of electronic component substrate and radiator during input power changes were tested by experiment. The results indicated that paraffin and composite of graphite with paraffin can shorten the time for electronic components reaching steady state. Temperature change rates declined. While the power increased abruptly, temperature between radiators and chips rose smaller and smoother when filled with paraffin and composite of graphite with paraffin, resulting in effectively restrain the adverse effects of heat shock on electronic components. In cooling process, the surface temperature of radiator filled with paraffin, composite of graphite with paraffin changed smoother, which was beneficial to extending the service life of radiator.
    Temperature distribution and heat loss experiments of low melting point molten salt heat storage tank
    CUI Wujun, WU Yuting, XIONG Yaxuan, LIU Shanwei, MENG Qiang, MA Chongfang
    2014, 65(S1):  162-167.  doi:10.3969/j.issn.0438-1157.2014.z1.026
    Abstract ( 634 )   PDF (2464KB) ( 241 )  
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    In order to study the temperature distribution and heat loss mechanism of molten salt heat storage tank, experiments of heating, internal cycle and natural cooling were conducted by using the molten salt storage tank in the solar trough heat collecting and transfer experimental system with low melting point molten salt developed by the laboratory. Molten salt temperature distributions in the heating and cooling process were obtained and the curves of heat loss with time and temperature were correlated. The results indicated that in heating process, obvious temperature stratification were observed in the molten salts tank below heater, but for natural cooling, no obvious temperature stratification were observed.
    Influence of opacifiers on thermal insulation properties of composite aerogels
    FANG Wenzhen, ZHANG Hu, QU Xiaodi, HE Yaling, TAO Wenquan
    2014, 65(S1):  168-174.  doi:10.3969/j.issn.0438-1157.2014.z1.027
    Abstract ( 877 )   PDF (2668KB) ( 460 )  
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    Aerogels are almost transparent to the near-infrared wavelengths, and therefore the opacifiers are widely doped to enhance aerogels insulation performances. Mie scattering theory was employed to calculate the mean extinction coefficient of composite aerogels doped with different kinds of opacifiers with different diameters and their shading effects were compared. A Hot Disk TPS2500S thermal analyzer based on the transient plane source method was used to measure the thermal conductivity of composite aerogels at different temperature and comparison with the theoretical analysis was conducted. The predicted thermal conductivities by theoretical model are in good agreement with the experimental data obtained by the Hot Disk thermal analyzer at different temperature. The results show that the optimal diameter of doped opacifiers is approximately at 3.5 μm, the shading effect of SiC opacifier is better than that of TiO2 and ZrO2, and there exists an optimal volume content of opacifiers (~3.75%) making the overall thermal insulation performance best. The developed theoretical model can be adopted to predict the influence of doped opacifiers on the effective thermal conductivity of composite aerogels.
    Design and analysis of plastic fin-tube heat exchanger for flue gas heat recovery
    CHEN Lin, SUN Yingying, LIANG Jiangtao, DU Xiaoze, YANG Lijun
    2014, 65(S1):  175-179.  doi:10.3969/j.issn.0438-1157.2014.z1.028
    Abstract ( 408 )   PDF (1205KB) ( 307 )  
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    Heat loss due to exhausted flue gas accounts for more than half of boiler's total heat losses. Flue gas heat recovery helps to reduce both fuel consumption and pollution emission, which is of great significance. One of the main problems in flue gas heat recovery that restricts the flue gas outlet temperature is the low temperature acid corrosion to metal heat exchangers. In order to overcome this problem, an anti-corrosion fin-tube heat exchanger based on thermally conductive plastic was designed as a low temperature economized. Using the heat recovery operational condition in a 1000 MW thermal power plant, the parameters of heat transfer area and outline dimensions of the heat exchanger were calculated by a validated mathematical model. Then, the influences of plastic thermal conductivity and number of flow paths on the design parameters were analyzed. It is hoped that the results in this paper could give some reference to engineering applications.
    Lattice Boltzmann simulation for heat and mass transfer in fractal porous media
    MA Qiang, CHEN Jun, CHEN Zhenqian
    2014, 65(S1):  180-187.  doi:10.3969/j.issn.0438-1157.2014.z1.029
    Abstract ( 451 )   PDF (3055KB) ( 366 )  
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    According to stochastic and fractal features of real porous media in nature, the reconstructed stochastic porous media with fractal features were generated by random midpoint displacement algorithm (RMD) and binaryzation processing. The relationship between Hurst exponent of fractal Brown surface and box dimension of reconstructed porous media was presented. Based on the fractal reconstructed theory, the reconstruction process of porous media was carried out based on a real porous media image, and the two-point correlation function was implemented to compare the structure characteristics between real porous media image and reconstructed porous media image. A lattice Boltzmann model (LBM) which was derived from the binary gas mixture theory was introduced to simulate the gas diffusion process in stochastic porous media. The feasibility of this model was validated by comparing with the analytical solution of unsteady diffusion process. The effective diffusivity of stochastic fractal porous media reconstructed by RMD with different Hurst exponent was calculated in this paper. For a given porosity, the positive correlation between the effective diffusivity and Hurst exponent was proposed. Using thermal lattice Boltzmann model, the heat conduction process in stochastic porous media was studied, and the effect of fractal features on effective diffusivity of porous media was presented.
    Numerical simulation of thermal radiation effect for plane window in aerodynamic thermal environment
    LIU Yuanchun, YUAN Zigui, LI Tianyu, HE Yurong, ZHU Jiaqi
    2014, 65(S1):  188-193.  doi:10.3969/j.issn.0438-1157.2014.z1.030
    Abstract ( 566 )   PDF (1473KB) ( 280 )  
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    In this paper, a finite element analysis is used to present the distributions of thermal fields and stress fields at different Mach numbers at an altitude of 15 km in a standard atmosphere for the CVD ZnS plane window. Then, the radiation intensity distribution of the window is obtained according to the temperature distribution. The results show that the temperature increases sharply in a short time, then the temperature distribution remains stable. The stress reaches the maximum value in an extremely short time and then decreases. The imaging quality of the plane window rapidly decreases with increasing the Mach number. The thermal radiation effect is one key factor for the quality of infrared image.
    Rheology characteristics for foam lamellae flow in a straight tube
    DU Dongxing, MA Xinjun, ZHANG Fahu, LI Yingge
    2014, 65(S1):  194-198.  doi:10.3969/j.issn.0438-1157.2014.z1.031
    Abstract ( 482 )   PDF (969KB) ( 244 )  
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    For understanding foam rheology in porous media, experimental investigations were carried out concerning foam lamellae flow characteristics in a straight tube. Foam is treated as single phase non-Newtonian fluid and its flow behavior was studied based on power law constitutive model. It is observed the film foam flow exhibits remarkably high apparent viscosity and obvious shear-thinning behavior, with flow consistency coefficient of K=0.11 and flow behavior index of n=0.61 for CO2 foam. Parameter studies were carried out for different internal gas types. It is found N2 foam is stronger than CO2 foam due to the water solubility of CO2 gas. Non-dimensional analysis was performed and a fit model with a threshold value of 0.71 was proposed based on experimental data, which indicates a startup pressure difference is necessary to mobilize the lamellae. The fit model is deemed to predict foam dynamic flow behavior in porous media in a more realistic and accurate manner.
    Rheological properties of vicoelastic fluid based nanofluid
    YANG Juancheng, XU Hongpeng, LI Fengchen
    2014, 65(S1):  199-205.  doi:10.3969/j.issn.0438-1157.2014.z1.032
    Abstract ( 724 )   PDF (3607KB) ( 312 )  
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    Viscoelastic fluid based nanofluid (VFBN) takes the advantages of turbulent drag reduction and convective heat transfer enhancement. Rheological properties of viscoelastic fluid are related with the mechanism of turbulent drag reduction. In order to get the rheology properties of VFBN, the VFBN with aqueous solution of cetyltrimethylammonium chloride/sodium salicylate as viscoelastic base fluid and copper nanoparticles as suspended nanoparticles was prepared. The mass fraction of viscoelastic fluids are 2.5×10-3, 5×10-3and 1×10-2, and the corresponding volume fraction of copper (spherical) nanoparticles are 0.1%, 0.25%, 0.5% and 1.0%, respectively. Experimental results indicate that VFBN shows obvious shear-thinning characteristics, the suspended nanoparticles can increase the zero-shear viscosity and enhance the viscoelasticity of base fluid. Based on the Giesekus constitutive equation, fitted correlations for the measured shear viscosity of VFBN have been obtained by modifying some experimental parameters.
    Analysis of thermal conductivity and viscosity of graphite suspensions
    MA Lei, WANG Jianjian, MARCONNET Amy, LIU Wei, CHEN Gang
    2014, 65(S1):  206-210.  doi:10.3969/j.issn.0438-1157.2014.z1.033
    Abstract ( 577 )   PDF (2231KB) ( 310 )  
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    Thermal conductivity and viscosity of graphite suspensions were experimentally studied by transient hotwire method and ARG2 method, respectively. By choosing different sonication time, thermal conductivity of graphite suspension at different volume fractions were obtained, as well as a thermal percolation behavior was observed. The viscosity shows opposite trend compared with thermal conductivity near percolation regime, which increases much faster before percolation than after percolation.
    Variation manner of mean free path of gas molecules in nano-porous space
    WANG Lixin, WEI Gaosheng, DU Xiaoze, YANG Yongping
    2014, 65(S1):  211-216.  doi:10.3969/j.issn.0438-1157.2014.z1.034
    Abstract ( 368 )   PDF (1274KB) ( 224 )  
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    Based on Zeng et al's model and in combination with simplified unit cell structure of cubic array of nano-spheres, the influencing factors, mechanism, and variation process of mean free path in nano-porous space are analyzed in this paper. The results show that the nano-porous structure features of nano-porous materials are directly related with specific surface area and density. The mean free path of gas molecules in nano-porous space decreases apparently with the rising of specific surface area and density. The nano-porous materials with a relative higher specific surface area and a larger density are more favorable for confining the gaseous conductivity in nano pores space. It is shown that p=104 Pa and p=4×105 Pa are two inflection pressures. When p<104 Pa, the mean free path of gas molecules almost does not change with vary of pressure. When p>4×105 Pa, the limiting effect of nano-porous structures on movement of gas molecules can be ignored. With the increase of temperature, the mean free path of gas molecules in nano-porous space is increasing, while, the increasing rate decreases gradually.
    Numerical simulation of heat transfer between air flow and ceramic foam in air receiver
    LI Qing, BAI Fengwu, ZHANG Yanan
    2014, 65(S1):  217-222.  doi:10.3969/j.issn.0438-1157.2014.z1.035
    Abstract ( 567 )   PDF (3445KB) ( 273 )  
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    A one-dimensional dynamic simulation model of the porous ceramic foam air receiver for solar power tower was established on Dymola. Rosseland radiation model and air properties variation with temperature and pressure were considered in this model. Modelica language was used in programming, which can solve the Algebraic Differential Equations automatically. The heat transfer between air flow and ceramic foam in the air receiver was studied. The influence on the temperatures of air and absorber, the time needed to reach steady, brought by the input radiation power, the thickness and average cell size of ceramic foam were analyzed.
    Numerical simulation of asymmetric flow in Venturi tube
    JIANG Yanhua, YANG Mo, GUO Chunsun, SHEN Siwei
    2014, 65(S1):  223-228.  doi:10.3969/j.issn.0438-1157.2014.z1.036
    Abstract ( 615 )   PDF (2320KB) ( 265 )  
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    In order to study the flow in the completely symmetric structure of the converging-diverging tube such as Venturi, the incompressible unsteady flow numerical models are established respectively for two dimensional channels and three dimensional tubes, and the numerical simulation method is adopted in the study. This paper confirms the flow bifurcation phenomenon, and mainly discusses the asymmetric flow in the symmetric structure. The simulation results show that, when Reynolds number reaches a critical value, the flow field in the symmetric Venturi tube will appear the asymmetric phenomenon, and produce irregular recirculation zones in the extended corner. In addition, the study indicates that the flow characteristics in the symmetric converging-diverging tube are affected by Reynolds number and geometry shape of tube, and the variation rules which flow asymmetric characteristics change with Reynolds number and geometry shape are obtained.
    Fields synergy analysis of turbulent heat transfer in helically coiled tube with non-uniform surface heat flux
    CUI Wenzhi, YIN Fei
    2014, 65(S1):  229-234.  doi:10.3969/j.issn.0438-1157.2014.z1.037
    Abstract ( 447 )   PDF (1540KB) ( 221 )  
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    Physical and mathematic models of fluid flow and heat transfer in helically coiled tube are established, and numerical simulations of the turbulent heat transfer in helically coiled tube are performed under the uniform and non-uniform heat flux boundary conditions. The results show that, when the same heating power is exerted to the helically coiled tube surface, the turbulent heat transfer coefficient of the uniform heat flux boundary is higher than that with non-uniform heat flux boundary, and the fields synergy angle of the uniform heat flux boundary is less than that with non-uniform heat flux boundary. Meanwhile, the turbulent heat transfer coefficient of small curvature is higher with the same Dean number under non-uniform heat flux boundary while the fields synergy angle is smaller. With the increase of the tube diameter, heat transfer coefficient in helically-coiled tube declines while the fields synergy angle raises.
    Analysis model of critical heat flux on downward facing curved surface for pool boiling
    HE Hui, PAN Liangming, CHEN Deqi
    2014, 65(S1):  235-239.  doi:10.3969/j.issn.0438-1157.2014.z1.038
    Abstract ( 339 )   PDF (1263KB) ( 187 )  
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    To facilitate the IVR (in-vessel retention) of molten core debris strategy at severe reactor accident, the capacity of ERVC (external reactor vessel cooling) is a key parameter, i.e. the CHF (critical heat flux) of the external reactor vessel should be higher than the related location heat flux. In this paper, an analysis model of CHF on the downward facing curved surface for pool boiling has been proposed, which adopts the Helmholtz instability analysis of vapor-liquid interface of the vapor jets which penetrating in the thin liquid film underneath the elongated bubble adhering to the lower head outer surface. When the heat flux closing to the CHF point, the vapor-liquid interface becomes highly distorted which resulted in obvious vapor blanket, it will block liquid to feed the thin liquid film underneath the vapor blanket from the bulk region. As a result, the thin liquid film will dry out gradually. As a consequence, the CHF occurs. Based on the aforementioned mechanism and the energy balance between the thin liquid film evaporation and water feeding, and taking the subcooling of the bulk water into account, the mathematic model about the downward facing curved surface CHF has been proposed. The CHF of the downward facing curved surface for pool boiling increases along with the downward facing orientation, and subcooling has significant effects on the CHF. Comparing the result of this model with the published experimental results, it shows good agreement under the both of saturated and subcooled boiling conditions.
    Numerical simulations of impinging heat transfer characteristics for multi-pulsating jets with phase difference
    GENG Liping, XU Qinggong, ZHENG Chuanbo, ZHOU Jingwei
    2014, 65(S1):  240-244.  doi:10.3969/j.issn.0438-1157.2014.z1.039
    Abstract ( 459 )   PDF (2163KB) ( 314 )  
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    A series of numerical simulations for multi-pulsating jets with phase difference are carried out in order to obtain impinging heat transfer characteristics. The results are compared with changed phase difference in jet modes and values and pulse frequency. Jet modes include the symmetrically increasing phase difference (mode A), the gradually increasing phase difference (mode B) and alternative phase difference (mode C). It can be found that mode B with gradually increasing phase mode has the best heat transfer characteristics within this research scope. When the phase difference lies between 0°-180°, the heat transfer characteristics become stronger with the increase of phase difference. When the phase difference is 120°, the heat transfer characteristics are best-distributed on the whole plate. Such well-distribution of heat transfer is also influenced by frequency. And the heat transfer characteristics are better-distributed when the frequency increase in the range of 0-10Hz. However, the influence of frequency is less than those of phase difference in jet modes and values.
    Thermodynamic analysis of reverse Brayton cycle refrigeration system based on single screw expanders
    WANG Wei, WU Yuting, MA Chongfang
    2014, 65(S1):  245-250.  doi:10.3969/j.issn.0438-1157.2014.z1.040
    Abstract ( 892 )   PDF (2460KB) ( 399 )  
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    Expansion refrigeration can obtain relatively larger temperature drop, and it had the potential of utilization on industrial energy saving, such as cryogenics air separation, light hydrocarbon recovery, expansion valve replacement and mine cooling, etc. At present, lots of large-scale gas expansion refrigeration systems have been applied in many industrial fields. In many actual industrial processes, there were tremendous demands for small-scale gas expansion refrigeration units. However, those systems didn't realize commercial application due to technical and economic bottleneck. So research and development small-scale reverse Brayton cycle refrigeration system was very important to energy conservation and emission reduction for our country. In this paper, a typical process of reverse Brayton cycle refrigeration system was presented and the thermodynamic model was established, the influence factors of internal heat exchanger and the adiabatic efficiency of expanders were analyzed. From the simulation result, it was concluded that internal heat exchanger couldn't improve the coefficient of performance for entire system, but could decrease the outlet temperature of expander efficiently. With the increase of reheat temperature difference, the effect of reheat reduced. Those works can provide the theoretic basis to study on small-scale reverse Brayton cycle refrigeration system.
    Simultaneous measurement of thermal properties and convective heat transfer coefficient of individual carbon fiber using Raman spectroscopy
    HU Yudong, LIU Jinhui, WANG Haidong, ZHANG Xing
    2014, 65(S1):  251-257.  doi:10.3969/j.issn.0438-1157.2014.z1.041
    Abstract ( 45 )   PDF (1558KB) ( 273 )  
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    The new developed laser-Raman method was used to measure the thermal conductivity of individual carbon fiber at 333.15 K. The local temperature along the individual fiber was determined by Raman shift. The measuring result without concerning thermal contact resistance is 110.6 W·m-1·K-1,which fits well with data from direct-current method. Then the method is made better. By changing laser heating spot, the thermal contact resistance is determined. And then the intrinsic thermal conductivity is determined to be 135.0 W·m-1·K-1 by concerning the thermal contact resistance. Moreover, by changing laser heating power the laser absorptivity is determined. And when the fiber is being heated in the air, the convective heat transfer coefficient is obtained by iterative solution.
    Analysis for influence of channel arrangements on performance of multi-media plate exchangers
    SONG Jiwei, HAN Ge, DU Tingting, CHENG Lin
    2014, 65(S1):  258-263.  doi:10.3969/j.issn.0438-1157.2014.z1.042
    Abstract ( 50 )   PDF (2673KB) ( 389 )  
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    For multi-media plate exchangers, compact is one of the important features, so, which can be used widely in the fields of waste heat recovery or heating system. But, the fluid channel arrangements are numerous and varied in the case of the channel number increasing, and the performance of multi-media plate exchangers will change in a wide range. The flowing and heat exchanging characteristics become more complex than two-fluid heat exchangers. Actually optimization of fluid channel arrangement can improve the performance of multi-media exchangers in the same initial conditions. The numerical method was utilized in this paper to analyze the influence of different fluids channel arrangements on the performance of a novel multi-media plate exchanger. And the entransy dissipation number was used as the objective function. Choose 26 kinds of arrangement in the range of 3-6 fluid channels. Correspondingly the entransy dissipation number and flow pressure loss of the novel multi-media plate exchanger were calculated. Under the same initial conditions, the conclusion showed that the total pressure loss reduced step by step with the fluid channel number increasing. In the case of same fluid channel number, different arrangements had very large impact on the value of entransy dissipation number of the plate exchanger. The value of the minimum entransy dissipation number with the same channel number will reduce with the channel number increasing. And also, the regular methods for channels arrangement to reduce the irreversible loss were summarized in this paper, which could provide some references for performance optimization of the multi-media plate exchanger.
    A new type of liquid-suction heat exchanger for automotive air conditioning system
    WANG Yan, YANG Jianfeng, ZENG Min, WANG Qiuwang
    2014, 65(S1):  264-271.  doi:10.3969/j.issn.0438-1157.2014.z1.043
    Abstract ( 534 )   PDF (3609KB) ( 272 )  
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    Liquid suction heat exchangers are commonly installed in refrigeration system with the intent of ensuring proper system operation and increasing system performance. Previous researchers have investigated performance of liquid suction heat exchangers, and some of them have concluded that the relative capacity change index (RCI) will increase with the increasing of heat recovery efficiency for certain refrigerants. In this study, two kinds of liquid suction exchangers set up with different baffles are numerical simulated by ANSYS FLUENT using the refrigerant R404A. They are used in an automotive air conditioning system and almost have the same geometrical parameters. The results indicated that for the same mass flow rate the overall heat transfer rate and average heat transfer coefficient of the shell-and-tube heat exchanger with continuous helical baffles (CH-STHX) are higher than that of the shell-and-tube heat exchanger (STHX) by 32.2% and 41.7%. The shell-side average heat transfer coefficient of the liquid refrigerant in the CH-STHX is about 3.5 times higher than that of the STHX. As the price of heat transfer enhancement, the shell-side pressure drop of the CH-STHX is extremely increasing to 11 times larger than that of the STHX. While the tube-side heat transfer coefficient and pressure drop of the CH-STHX almost keep the same with that of the STHX. And most importantly, the heat recovery efficiency increases from 0.21 to 0.29 for the CH-STHX, by 38.1%.
    Flow dead zones in shell side of shutter baffle heat exchanger
    GU Xin, WANG Ke, HAO Jianshe, LIU Minshan, PAN Guohua
    2014, 65(S1):  272-276.  doi:10.3969/j.issn.0438-1157.2014.z1.044
    Abstract ( 697 )   PDF (2507KB) ( 320 )  
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    The size and distribution regularities of flow dead zone of shutter baffle heat exchanger were researched by numerical simulation and experiment. It is concluded that the size of flow dead zone in shell side of shutter baffle heat exchanger is reduced with increase of Reynolds number. The size and distribution of flow dead zone are affected by assemble types of shutter baffles. When the shutter baffle is co-rotating arranged, the size of dead zone in shell side was less than that of symmetrical. When Re=5000,Re=10000 and Re=15000, the dead zone in shell side of shutter baffle heat exchanger with shutter baffle co-rotating arrangement are respectively 50.5%、51.6%、43.0% of that with shutter baffle symmetrical arrangement.
    Cooling effects of a rotating cylinder under a side impinging air slot jet
    XU Rui, LI Changfeng, WEI Jiaxing, YU Yanfei, HOU Jinliang
    2014, 65(S1):  277-284.  doi:10.3969/j.issn.0438-1157.2014.z1.045
    Abstract ( 399 )   PDF (3673KB) ( 219 )  
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    The heat transfer characteristics of a rotating cylinder under a side air impinging jet were experimentally investigated in this study. In practical industrial applications, such as food processing, textile and paper drying process, there are heat transfer and mass transfer problems on the side of the rotating cylinder under impinging jet flow. The height and diameter of the cylinder were fixed, and the variable parameters were as follows: (1) the jet Reynolds number (Rej=655-60237); (2) the rotational Reynolds number(Rer=1975-7899); (3) the ratio of the cylinder diameter (D) to the nozzle width (w) (D/w=2-16); (4) the relative jet-impinging distance (L/w=1-16, L is the shortest nozzle-to-cylinder distance). This experiment measured local average temperature on the heated wall surface of the cylinder using thermocouples under stationary and rotating condition. The experimental results showed that the rotation allowed the surface temperature of the cylinder to tend towards uniformity along the circumferential direction of the cylinder. In addition, the heat transfer experiment included the pure rotating condition, the pure jet-flow condition and the coexistent condition of rotation and jet flow. The results showed that the average Nusselt number (Nu) increased with the increase of Rej and Rer, and decreased with the increase of D/w. The influence of D/w on Nu decreased with the increase of L/w, and Nu first increased and then decreased with the increase of L/w. In other words, there is a critical L/w value that can produce the highest Nu, and the critical L/w value increased with D/w. Finally, this study proposed reasonable and accurate empirical correlations of Nu in view of three test conditions. All the results can provide reference for practical design of the cooling system in relevant power machinery.
    Theoretic analysis on transient solidification behaviors of a molten blast furnace slag particle
    LIU Xiaoying, ZHU Xun, LIAO Qiang, WANG Hong
    2014, 65(S1):  285-291.  doi:10.3969/j.issn.0438-1157.2014.z1.046
    Abstract ( 449 )   PDF (3130KB) ( 282 )  
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    A theoretic analysis is performed with temperature model on transient air cooling and solidification behaviors of a spherical molten slag particle. With considering the variation of thermal conductivity with temperature and the radiation between slag and environment, the temperature distribution and the transient moving of phase-change interface inside the particle are obtained by applying the finite difference method. The effects of variable thermal conductivity, heat transfer boundary condition, slag particle size, air flow rate and initial temperature of the slag particle are discussed. The simulation results indicate that the variable thermal conductivity of the slag extends the solidification process, while the radiation significantly improves the cooling speed. Meanwhile, the solidification process is speeded up with increasing air flow rate and decreasing particle size. The cooling and solidification process is prolonged for the slag particle with higher initial temperature.
    Convection thermal resistance calculation method and validation based on generalized theory
    LENG Xueli, TIAN Maocheng, QIU Yan, BAI Chao
    2014, 65(S1):  292-296.  doi:10.3969/j.issn.0438-1157.2014.z1.047
    Abstract ( 363 )   PDF (2535KB) ( 219 )  
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    The entransy dissipation and generalized thermal resistance theory is utilized in researching dissipation and generalized transfer temperature difference in convection. Three computing forms of heat transfer resistance for control volume is proposed and validated by two-dimensional laminar convection in parallel channels. Traditional surface heat transfer coefficient does not accurately reflect the thermal conductivity (resistance) capabilities of control volume while compare with it. The generalize resistance method is reliable for two reasons, first is that three forms of expression consistent with others perfectly, second is that the thermal resistance consistent with conduction while convection degenerate to conduction. The validation of convection in parallel flow shows that the basically general trend of generalized thermal resistance increases with flow development, consistent with basic idea of convective heat transfer. On the while, the definition style of thermal resistance does not increase with flow in several circumstance and influenced by temperature and transfer quantity obviously, due to the definition type simplify the expression of thermal resistance construction.
    Simulation of loop heat pipe start-up characteristic
    HUANG Jie, WANG Naihua, CHENG Lin
    2014, 65(S1):  297-302.  doi:10.3969/j.issn.0438-1157.2014.z1.048
    Abstract ( 552 )   PDF (2766KB) ( 318 )  
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    Two loop heat pipes (LHP) with parallel connection are used to cool the condenser of Alpha Magnetic Spectrometer 02(AMS-02).However, a series of factors lead to only one of LHPs primarily setting up and the other one failing to set up. The article established three-dimensional model of the LHP evaporator, used FLUENT to simulate its start-up temperature field. It is concluded that higher heat load facilitate start-up. Contact thermal resistance produced by structure or equipment difference can cause failure start-up. Finally, wick with primary and second wicks is better for start-up than wick of one single material.
    Thermodynamics and thermal stress analysis of TEG under high heat flux condition
    WU Yongjia, MING Tingzhen, PENG Keyuan, SHEN Wenqing
    2014, 65(S1):  303-307.  doi:10.3969/j.issn.0438-1157.2014.z1.049
    Abstract ( 414 )   PDF (909KB) ( 274 )  
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    Thermoelectric generator is a device taking advantage of the temperature difference in thermoelectric material to generate electric power, where the higher the temperature difference of the hot-cold ends, the higher the efficiency will be. However intensive thermal stress level in solar thermoelectric generator (TEG) model provoked by high heat flux is responsible for structure failure of the device, which negatively influences the expected lifecycle of thermoelectric module. Based on the fact, three-dimensional TEG models with different geometries are employed to examine the effect of the conducting strip, ceramic plate and tin soldering geometry configuration on the module's stress level. The simulation results indicate that decreasing ceramic plate thickness, shortening thermo-pins distance, reducing copper strip thickness will effectively alleviate thermal stress intensity in the module.
    Pool boiling experiment on TiO2 nanotube array surface
    MO Dongchuan, ZHANG Hui, LÜ Shushen
    2014, 65(S1):  308-315.  doi:10.3969/j.issn.0438-1157.2014.z1.050
    Abstract ( 478 )   PDF (2735KB) ( 227 )  
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    Micro-scale modification surface are usually used to enhance the pool boiling heat transfer, but the characteristics and mechanisms that how the nano-scale affects the pool boiling is still not clear.A series of TiO2 nanotube array surface with different diameters are fabricated by electrochemical anodization and the pool boiling heat transfer performance with saturated deionized water on different TiO2 nanotube array surface were experimentally investigated in this paper. Different Ti surface were prepared and their pool boiling heat transfer performance were also investigated for comparison. Before and after each pool boiling experiment, the contact angle of pure water on the surface of each sample was observed to test the surface wettability. A high speed camera was used to record the bubble dynamic process in the experiment. The results showed that the pool boiling heat transfer performances with different TiO2 nanotube array were quite different. But the enhanced effect was not monotonic variation with the diameter increasing, which indicates that the diameter is not the only one of most important points on the pool boiling performance. In fact, the diameters of the TiO2 nanotube here were smaller than the cavity diameter, and it was difficult to generate cavity. As a result, very small bubble was not observed. Anyway, all TiO2 nanotube array had good surface wettability, and they can significantly enhance the critical heat flux (CHF) as much as 116% of the Ti surface. But the high temperature and large interfacial velocity during pool boiling are detrimental to the TiO2 nanotube array, and some TiO2 nanotube array may be damaged after the CHF, which leads to a significant CHF decreasing in the next pool boiling experiment.
    Laminar heat transfer characteristics in circular tubes with twisted tapes of alternate axes
    WANG Te, WANG Feilong, FAN Aiwu, LIU Wei
    2014, 65(S1):  316-322.  doi:10.3969/j.issn.0438-1157.2014.z1.051
    Abstract ( 428 )   PDF (3150KB) ( 246 )  
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    In order to improve the performance of laminar heat transfer in a tube, three types of twisted tape with alternate axes were designed. Numerical study was performed on the laminar heat transfer characteristics in circular tubes inserted with these different twisted tapes. The results show that, (1) For the case with short-width twisted tape of alternate axes, Nusselt number (Nu) increases with the increment of the dislocation angle under small Reynolds number (Re); but for large Re, the impact of dislocation angle grows negligible. However, a sudden decrease of Nu occurs at large Re for the small dislocation angles cases. The dislocation angle has an insignificant effect on the friction factor (f). The value of performance evaluation criterion (PEC) is the highest for the case with a 90° dislocation angle. (2) For the case with center-cleared twisted tape of alternate axes, the largest Nu is reached at the 60° dislocation angle. The friction factor f is relatively larger than that when the dislocation angle is 0°, and it exhibits an obvious increment with the dislocation angle. The PEC value demonstrates a complex variation with the dislocation angle. However, in general, the thermo-hydraulic performance is the best for the case with a 60° dislocation angle. (3) For the case with center-cleared short-width twisted tape of alternate axes, the Nu increases with the increment of the dislocation angle under small Re; but at large Re, the differences for different dislocation angle is limited. The dislocation angle has an insignificant effect on the friction factor (f). The PEC value is the highest for the case with a 90° dislocation angle. But the sudden decrease of Nu does not occur at large Re for the small dislocation angles cases. The largest f appears when the dislocation angle is 60°, but the differences between the cases with different dislocation angles are small. Moreover, the friction factor f is reduced by a great extent as compared with short-width twisted tape of alternate axes. The variation tendency of PEC is similar to that of Nu, and it performs best at the 90° dislocation angle. (4) In summary, a better comprehensive thermo-hydraulic performance could be obtained by applying the center-cleared short-width twisted tape of alternate axes.
    Heat transfer characteristics of supercritical carbon dioxide in a micro-capillary tube
    WANG Ke, XIE Jin, LIU Zunchao, LIU Tong, MA Lu
    2014, 65(S1):  323-327.  doi:10.3969/j.issn.0438-1157.2014.z1.052
    Abstract ( 550 )   PDF (2863KB) ( 304 )  
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    Three-dimensional model of single tube with an inner diameter of 1.31 mm was established; using CFD software Fluent, the flow and heat transfer characteristics of supercritical carbon dioxide in the micro-capillary tube was analyzed. The influences of the heat flux, inlet mass flow rate, flow direction and pressure on the heat transfer of supercritical carbon dioxide and pressure drop are analyzed. It was shown that: boundary wall thinning by increasing the import mass flow rate; which could enhance heat transfer. Changing the heat flux has little influence on heat transfer and pressure drop of supercritical carbon dioxide. Due to the effects of gravity and buoyancy, the impact of the flow direction on the heat transfer performance was large; the heat transfer coefficient of vertically upward fluid flow is greater than that of the vertical downward flows and horizontal flow.
    Numerical simulation analysis of gypsum-based phase change energy storage component
    CUI Na, XIE Jingchao, LIU Jiaping, WANG Wei, LI Yue
    2014, 65(S1):  328-335.  doi:10.3969/j.issn.0438-1157.2014.z1.053
    Abstract ( 624 )   PDF (3121KB) ( 441 )  
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    In order to solve phase change energy-saving technology applications in building envelope thermal design and improve indoor thermal comfort, experimental and theoretical studies about phase change component were carried out in this paper.The composite phase change component with different mass of phase change material was made of super-hemihydrate plaster and paraffin phase change material. DSC method was used to test phase change energy storage gypsum board's phase change temperature and phase change latent heat and steady-state test method was used to test thermal conductivity of different proportions of the component. Phase change heat transfer model was established and simplified. Heat transfer process and heat transfer mechanism of the component were analyzed. Solved by numerical simulation to study the effect of different proportions of phase change component in the Beijing area. Changing thermal conductivity and convective heat transfer coefficient respectively, application effects were studied for opotimization. The results show that along with the rising of the paraffin content, the thermal conductivity of phase change component minished. Among the four kinds ratio, component with 33% PCM had the best application effect in passive buildings in Beijng and in transition season its energy-saving amount was 10% more than that in traditional buildings. Enlarging thermal conductivity and convective heat transfer coefficient of phase change component can both improve indoor comfort and reduce energy consumption. The results of the research can provide a reference for building envelope thermal design with phase change material.
    Energy transfer conversion mechanism and minimum entropy generation principle for convective heat transfer enhancement
    LU Xiaoping, YU Shurong, YU Jianping, HE Ailing, GUO Dandan
    2014, 65(S1):  336-339.  doi:10.3969/j.issn.0438-1157.2014.z1.054
    Abstract ( 678 )   PDF (419KB) ( 341 )  
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    According to the relationship between generalized force and generalized flow, established all phase entropy generation rate equation, and analysed the relationship between entropy flow and total entropy generation of system. The results show that when the steady state, the decreasing of total entropy generation of system, the increasing of entropy flow and heat transfer, specifically, in the case that heat and mass transfer processes are both spontaneous process. When mass flow and heat flow are in the same phase, the decreasing of phase difference between mass flow and heat flow, the increasing of heat transfer, which reflects field synergy mechanism of energy transfer between two spontaneous process, with positive entropy generation rate,while in the case that heat transfer is nonspontaneous process, and mass transfer is spontaneous process. When mass flow and heat flow are in the opposite phase, the increasing of phase difference between mass flow and heat flow, the increasing of heat transfer, which reflects the thermodynamic coupling mechanism of energy conversion between spontaneous process,with positive entropy generation rate,and nonspontaneous process, with negative entropy generation rate. Between mass flow and heat flow from the same phase to the opposite phase, corresponding to the energy transfer mechanism of field synergy,and the energy conversion mechanism of thermodynamic coupling, all reflecting the minimum entropy generation principle for convective heat transfer.
    Three-dimensional simulation of solidification and heat transfer for air-cooling molten blast furnace slag droplet
    QIU Yongjun, ZHU Xun, WANG Hong, LIAO Qiang
    2014, 65(S1):  340-345.  doi:10.3969/j.issn.0438-1157.2014.z1.055
    Abstract ( 758 )   PDF (2378KB) ( 400 )  
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    Solidification and heat transfer of an air-cooling molten blast furnace slag droplet is numerically simulated by the volume of fluid (VOF) method coupling with the solidification/melting model. The effects of droplet diameter and air velocity are investigated on the dynamic solidification evolution and heat transfer of the slag droplet, respectively. The results show that it is available for the air-cooling technique to realize fast solidification of the molten slag droplet surface, while non-uniform solidification evolution is found to occur inside the slag droplet. The solidification process of the molten slag droplet is expedited with decreasing droplet diameter and increasing air velocity due to the enhancement in the heat transfer. The optimum slag droplet diameter and air velocity should be comprehensively determined for a practical heat recovery system. As for a droplet with diameter of 0.5-2 mm at initial temperature of 1673.15 K, it releases the heat of solidification within 2 s under air velocity of 1-5 m·s-1, and the highest air outflow temperature as a result can reach above 900 K.
    Mathematical model of continuous working process of marine steam accumulator and its performances simulation
    GUO Jiamin, SUN Baozhi, LEI Yu, ZHANG Guolei, YANG Longbin, LI Yanjun
    2014, 65(S1):  346-352.  doi:10.3969/j.issn.0438-1157.2014.z1.056
    Abstract ( 511 )   PDF (2976KB) ( 330 )  
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    According to the characteristics of marine steam accumulator, the mathematical model of continuous working process of marine steam accumulator which considered the evaporation (condensation) relaxation time is established. The accuracy of the model is validated by the experimental results of the marine steam accumulator. On this basis, the influence of the key parameters on the dynamic characteristics of the continuous charging and discharging process is studied with the simulation model. The water filling coefficient of marine steam accumulator determines the heat storage capacity of marine steam accumulator and restricts the maneuverability of the system. However, the charge and discharge pressure not only influence energy storage and conversion efficiency, but also play a key role for optimizing the volume of steam accumulator. So the relationship of the water filling coefficient and the charge and discharge pressure should be matched reasonably by taking into account the requirements of steam catapult system about the launch cycle, steam pressure and the quantity of steam, to make it not only satisfy the launch efficiency but also achieve the required steam parameters for aircraft take-off.
    Permeability measurement method of crushed tight porous medium
    ZHOU Bo, XU Ruina, JIANG Peixue
    2014, 65(S1):  353-358.  doi:10.3969/j.issn.0438-1157.2014.z1.057
    Abstract ( 585 )   PDF (1595KB) ( 357 )  
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    A model for flows in low permeability porous media with nano scale pores has been derived with assumptions including homogeneity, the Darcy's law, ideal gas model and the Klinkenberg effect. Numerical simulations are carried out for pressure pulse decay experiment with spherical crushed samples using the finite difference method with suitable boundary conditions. Non-dimensional parameters Z,Z* and bK are introduced when the governing equations are non-dimensionalized. Various pressure decay curves are investigated numerically when various parameters Z,Z* and bK are applied. A data processing method for the present pressure pulse decay experiment is proposed. Porosity, permeability and the Klinkenberg coefficient can be determined by combining both the measured pressure decay curves at the sample boundaries and the numerical solutions of the governing equations. The permeability and the Klinkenberg coefficient of a porous medium sample cannot be determined using only one pressure decay curve.
    Influences of capillary structures on flat plat heat pipe performance
    WANG Chen, LI Yanxia, LIU Zhongliang, ZHANG Guangmeng, ZHANG Ming
    2014, 65(S1):  359-363.  doi:10.3969/j.issn.0438-1157.2014.z1.058
    Abstract ( 458 )   PDF (1979KB) ( 382 )  
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    Experimental investigations of flat plate heat pipes (FPHP) are presented. The capillary structures of the three tested FPHPs are intersected narrow grooves on evaporation surface (FPHP 1), interlaced channels(FPHP 2) and intersected micro-grooves on both evaporation surface and condensation surface(FPHP 3). The experimental results showed that FPHP 3 has the smallest thermal resistance and the best axial heat conduction ability, while FPHP 2 has the largest thermal resistance and the poorest axial heat conduction ability. FPHP 3 also has the best radial temperature-leveling performance while the other two are of a similar radial temperature-leveling ability. Therefore, the intersected micro-grooves on both evaporation surface and condensation surface are the best capillary structure for flat plate heat pipes. The reason is perhaps the structure enhances both the boiling heat transfer on the evaporation surface and the condensation heat transfer on the condensation surface.
    Analysis on structural stress of tube in steam generator based on fluid-structure interaction
    SUN Baozhi, ZHENG Lusong, HAN Wenjing, ZHANG Guolei, LIU Shanghua
    2014, 65(S1):  364-370.  doi:10.3969/j.issn.0438-1157.2014.z1.059
    Abstract ( 401 )   PDF (4753KB) ( 385 )  
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    Taken the steam generator of nuclear power plant as the prototype, the vapor-liquid two-phase flow and the boiling heat transfer were simulated by two-fluid model. The coupled flow and heat transfer process between the fluid of the primary and secondary sides and the heat transfer tubes with support plates was numerically simulated using CFX software. Based on the flow and heat transfer calculation, the pressure of fluid in the primary and secondary sides was extracted. The pressure load was transferred to the structure model in Workbench. And the structural stress of tube was calculated. The fluid-structure interaction results show that there is an abrupt increase in secondary velocity at the positions of support plates. The fluid pressure loss of secondary side increases because of the increase of fluid turbulence dissipation. The pressure stress of the heat transfer tube depends on the pressure difference between the primary side and the secondary side. The overall average of the pressure stress is about 58 MPa, which is consistent with the actual measured parameter.
    Influence of high temperature composite insulation structure on its transient thermal characteristics
    AI Qing, LIU Hua, XIA Xinlin, HAN Jiecai
    2014, 65(S1):  371-376.  doi:10.3969/j.issn.0438-1157.2014.z1.060
    Abstract ( 604 )   PDF (1789KB) ( 404 )  
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    A heat transfer model combined conduction, radiation and phase change for multilayer composite insulation structure is built in this paper, radiative heat transfer in semitransparent participating material of the composite insulation structure is simulated by Monte Carlo method (MCM), and then be regarded as radiative source term of the energy equation, while energy equation is solved by finite volume method (FVM). Transient heat transfer characteristics of three different typical composite insulation structures, which are respectively composed of fiber blanket insulation and metal film, fiber blanket insulation, fiber reinforced aerogel and metal film, fiber blanket insulation, fiber reinforced aerogel, phase change insulation materials and metal film composite insulation structure, are analyzed and compared. Computational results show that the structures and components of the composite insulation significantly influence its transient heat transfer characteristics. The proposed research work can provide guidance for optimization design of the composite insulation structure.
    Impact of multiphase and turbulence models on hydrodynamics simulation of commercial flat-sheet MBR
    YU Dawei, WEI Yuansong, ZHENG Xiang, FAN Yaobo, WEI Ding
    2014, 65(S1):  377-385.  doi:10.3969/j.issn.0438-1157.2014.z1.061
    Abstract ( 19 )   PDF (3956KB) ( 215 )  
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    Phase distribution and velocity field sketch out hydrodynamics characteristics of flat-sheet MBR (membrane bioreactor), which could be analyzed by multiphase and turbulence models efficiently. Aiming at structure optimization, fouling mitigation and energy reduction for MBR, flat-sheet membranes of three major domestic and abroad companies, including Kubota, Toray and SINAP, were chosen to investigate spatial structure of commercial submerged flat-sheet MBR, and to compare effects of different multiphase and turbulence models on phase distribution, velocity field and computational expense. Results showed that the spatial structure of all three flat-sheet membrane was usually designed according to company's manuals, resulting that ratios of length/width and height/diameter were in the range of 1.37±0.63 and 0.97±0.23, respectively. Multiphase model plays key roles rather than turbulence models in phase distribution and velocity field simulation, and the combination of VOF (volume of fluid) and standard k-ε is more accurate and faster for simulating velocity field of submerged flat-sheet MBR. Multiphase model is the key factor of affecting computational costs. On 6 cores platform, VOF consumes 4.5-2.2 times more CPU time than mixture, and realizable k-ε consumes almost the same time as standard k-ε.
    Influence of ultrasonic treatment on NaCl aqueous solution and MgSO4 aqueous solution in nanofiltration membrane transport
    MU Chao, HU Guoxin
    2014, 65(S1):  386-390.  doi:10.3969/j.issn.0438-1157.2014.z1.062
    Abstract ( 517 )   PDF (2426KB) ( 270 )  
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    The potential use of ultrasonic treatment on the nanofiltration membrane for enhancing the electrolyte aqueous solution in the nanofiltration membrane transport was investigated. The mechanisms for mass transport of the electrolyte solution in the nanofiltration membrane with ultrasonic treatment were researched by an embedded ultrasound transducer and the cross-flow nanofiltration integrated experiments with NaCl and MgSO4 in single-salt aqueous solution, the operating variables studied were feed concentra-tion (2-30 mol·m-3) and applied pressure (0.1-0.26 MPa). It was observed that the observed rejections of NaCl and MgSO4 with ultrasonic treatment were lower than those without ultrasonic treatment in constant feed concentration. However, the membrane flux and streaming potential with ultrasonic treatment were higher than those without ultrasonic treatment in constant feed concentration.
    Particle swarm optimization with two new strategies for heat exchangers network synthesis
    HE Qiaole, CUI Guomin, XU Haizhu
    2014, 65(S1):  391-397.  doi:10.3969/j.issn.0438-1157.2014.z1.063
    Abstract ( 345 )   PDF (1186KB) ( 180 )  
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    The optimization of heat exchanger networks synthesis (HENS) still remains an open problem because of the complexity nature of stream matches. The complexity of mixed integer nonlinear program (MINLP) keeps the opening for the heuristic algorithms including particle swarm optimization (PSO), and the HENS play an important role in the chemical process optimization. Two strategies that dedicated to improve the performance of PSO for optimal design of heat exchanger network are proposed. Although the standard PSO algorithm is capable of detecting the promising region, it exhibits the deficiency of that they cannot perform a refined local search to compute the optimum with high accuracy once there. The matter that the best position ever recorded is not the true minimum fitness will lead to the excessive roaming the search spaces and frequent updating. Local search technique to overcome above difficulties was proposed. In local search component, two local search strategies that perform more refined search around potential solutions of particle at hand were proposed. In cases take consideration of the fixed equipment cost, a formula alteration strategy was proposed to overcome the matter that, due to existence of the non-zero fixed equipment cost a, the evolution will likely to be trapped into a local optimum. Since the area cost is relatively small compared with the fixed equipment cost a in the initial iteration phase of evolution. The proposed strategies has been applied to several four streams cases taken from the literature and the results are very encouraging. The presented case studies revealed special search ability in local optimization incorporated with the proposed strategies.
    Anti-fouling properties of electroless Ni-W-P deposit on heat transfer surface
    CHENG Yanhai, CHEN Hengyang, YANG Jinyong, HAN Dongtai, ZHU Zhencai
    2014, 65(S1):  398-402.  doi:10.3969/j.issn.0438-1157.2014.z1.064
    Abstract ( 571 )   PDF (1898KB) ( 346 )  
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    In the present work, ternary Ni-W-P deposits with different tungsten content were prepared by varying sodium tungstate concentration in electroless plating. Studies on phase transformation behavior carried out by differential scanning calorimetry (DSC) showed that Ni-W-P deposits exhibited higher thermostability and activation energy with the increase of W composition. Further fouling experiments indicated the surfaces of Ni-W-P deposits with different W content inhibited the adhesion of fouling compared with the mild steel surface. However, there is not necessarily a relationship between the fouling adhesion rate and surface roughness or free energy of the ternary Ni-W-P deposits, but is intimately related to the W content.
    Microwave-assisted synthesis of cupric(Ⅱ) complex with porphyrin and its interaction with c-myc G4 DNA
    SUN Fuqiang, MEI Wenjie, WU Weili, WU Jian, ZHANG Zhao, ZHANG Ziyi, CUI Yingde
    2014, 65(S1):  403-408.  doi:10.3969/j.issn.0438-1157.2014.z1.065
    Abstract ( 22 )   PDF (1240KB) ( 148 )  
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    5,10,15,20-tetra(4-merhoxyphenyl)porphyrin (TMOPP) was synthesized from pyrrole and p-methoxybenzaldehyde in propanoic acid solution at 130℃. Then, TMOPP and 1,4-dibromobutane were mixed in DMF solution at 100℃ to prepare target complex(CuTMOPP) under microwave-assisted with the yield of 64.7% in 20 min. The target compound was characterized by using ESI-MS, UV and IR spectra. Further, the binding behaviour of CuTMOPP with c-myc G4 DNA was investigated via FRET melting point methods, as well as spectroscopy methods. The results indicated that the target compound CuTMOPP may bind c-myc G4 DNA by electrostatic binding mode, as a result, the replication of c-myc G4 DNA was blocked, and an evaluation of biological activity is now in progress.
    Calculation of electrostatic potential of low conductivity hydrocarbon products and liquid hydrogen in tanks
    DONG Juhui, HUANG Yonghua
    2014, 65(S1):  409-414.  doi:10.3969/j.issn.0438-1157.2014.z1.066
    Abstract ( 610 )   PDF (2236KB) ( 257 )  
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    Static electricity can be generated at the interface between a fluid and a solid surface. Hydrocarbon products as well as liquid hydrogen in chemical and energy industry are of low conductivity, inflammable and explosive, which enables the static charge easily accumulated, resulting in high electric potentials and electric fields during its transportation and storage. To avoid safety hazard due to sparks of sufficient energy for an explosion to occur inside a tank, this paper studied the formation and distribution of electrical potential of some typical hydrocarbon products and liquid hydrogen in cylindrical vessels. Poisson equation and Laplace equation were solved by using Bessel function to get the potential value distribution of liquid and gas in the tanks. The impact parameters such as tank structure, fluid properties and charge density to the potential were analyzed. The potential variation behavior against the above parameters was obtained. It was found that the maximum static potential appears at about 72% of the liquid level/height from the bottom instead of the liquid-gas interface. The calculations also showed that the potential reaches its crest value for each fluid studied when the filling rate is 65%-75% of the full capacity. Some suggestions were given for design of low conductivity fluid tanks to avoid high electric potential safety hazard.
    Low gas velocity of PEMFC aided by gravity water drainage
    PEI Houchang, TU Zhengkai, LIU Zhichun, SHEN Jun, QIU Zizhao, LIU Fan, LIU Wei
    2014, 65(S1):  415-420.  doi:10.3969/j.issn.0438-1157.2014.z1.067
    Abstract ( 447 )   PDF (3247KB) ( 279 )  
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    Low gas velocity in proton exchange membrane fuel cell (PEMFC) can be occurred as gas distribution inconformity. Low gas velocity of PEMFC aided by gravity water drainage was investigated experimentally. It released that gravity can help droplets separate from gas diffusion layer (GDL) which help the liquid water drainage from PEMFC stack too. The experiment released that the performance of stack will be the best when the cathode downward and the droplet gravity accordance to the orientation of the droplet separate from GDL; Gravity drops consistent with the direction of purge gas in the PEMFC stack when the channel was vertical which improved the water management. In different orientation of PEMFC stack channel the output of stack would be increasing as the temperature rising when the reaction gas flow rate was low. The gas humidification had little effect on stack performance when the channel was vertical. It should be avoided that the cathode was horizontal and upwards when the stack was working.
    Mass transfer enhancement of proton exchange membrane fuel cell
    SHEN Jun, ZHOU Bing, QIU Zizhao, TU Zhengkai, LIU Zhichun, LIU Wei
    2014, 65(S1):  421-425.  doi:10.3969/j.issn.0438-1157.2014.z1.068
    Abstract ( 426 )   PDF (2739KB) ( 239 )  
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    The improvement of proton exchange membrane fuel cell (PEMFC) performance depends on the ability of mass transfer. Based on the theoretical analysis, the investigation focusing on the enhancement of mass transfer has been carried out using three dimension model through two methods, adding blocks in gas channel and perforation of gas diffusion layer (GDL). The results show that the two methods above would effectively strengthen the ability of mass transfer and improve the performance of the PEMFC. What's more, extra parasitic power would be needed and the effect of adding blocks should be comprehensively evaluated.
    Numerical simulation of laser ablation properties of irradiated material
    ZHAO Yang, ZHANG Haochun, LI Yao, YU Haiyan, GUO Yangyu
    2014, 65(S1):  426-432.  doi:10.3969/j.issn.0438-1157.2014.z1.069
    Abstract ( 406 )   PDF (1715KB) ( 267 )  
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    High power laser irradiation damage was mainly caused by three aspects as thermal, mechanical and radiation damages of the material, and direct characterization parameters for laser ablation was the thermal and mechanical effects of the material caused by laser irradiation. According to performance indicators and damage models of an airborne laser (ABL) weapon system, design framework and algorithmic process for ABL simulation system were build and the appropriate mathematical and physical models were established. Discrete method was used for solving the heat conduction equation, and the key parameters to characterize the ability of laser damage were obtained. Probability of damage occurrence for materials was simulated under different operating conditions, and the factors to affect damage probability were also analyzed.
    Preparation and properties of in-situ crosslinked feather keratin hybrid films with using γ-glycidoxypropyltrimeth oxysilane as crosslinking agent
    DENG Xiangwen, YIN Guoqiang, ZHANG Buning, HE Ming, DOU Yao, WANG Haiyang
    2014, 65(S1):  433-440.  doi:10.3969/j.issn.0438-1157.2014.z1.070
    Abstract ( 588 )   PDF (2357KB) ( 442 )  
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    The in-situ crosslinked feather keratin-silica hybrid films were successfully prepared by solvent casting in the presence of glycerol and γ-glycidoxypropyltrimethoxysilane (KH560). The structure and properties of the feather keratin-silica hybrid films were characterized by means of FTIR,TG,SEM and contact angle tests. The effect of KH560 amounts on the mechanical properties,thermal stability and the surface and bulk hydrophobicity was investigated. The results showed that in thermal and alkaline processed conditions, KH560 reacted onto feather keratin chains through the amino-oxirane addition reaction. Simultaneously the methoxysilane groups (Si-O-CH3) hydrolyzed to form silanol groups (Si-OH) and the condensation reaction of the silanol group (Si-OH) would form Si-O-Si linkages to result in a crosslinked structure. The crosslinking treatment improved the mechanical strength,thermal stability and the surface and bulk hydrophobicity.
    A pilot study of flame arrester performance test methods
    SUN Shaochen, BI Mingshu, LIU Gang, LIU Duo
    2014, 65(S1):  441-450.  doi:10.3969/j.issn.0438-1157.2014.z1.071
    Abstract ( 15 )   PDF (2437KB) ( 343 )  
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    The combustible gas explosions occurred frequently in modern industry,and these hazards have resulted in a great amount of casualties and property losses. So the research of combustion and explosion of combustible gas in pipeline has become an important subject in the fields of safe technology. Flame arrester is a kind of safety equipment which can prevent flammable gas and liquid vapors from spreading,and widely used in petrochemical and natural gas industry in recently years.As a class of safety equipment, flame arrester is installed in the import and export of the device or pipe. Element which is the core components of flame arrester allows media circulation and block off the flame. With the development of modem society,people pay much attention on safe production. Accordingly,the performance test on flame arresters used for safe production seems to be necessary.The research of the flame arrester related detection technology started very later in China, and relative to the foreign standards, domestic standards technology is backward in technology, shorter period of refresh technology, incomplete standard system. So in this paper the study of flame arrester performance test method is carried out, in order to improve the detection level in this field, and promote the existing technology that complete performance detection of flame arrester. At the same time, it will be benefit for both of explosion prevention and the security of production and people.
    Research and development of zeolite membrane seed coating machine
    WANG Jinhong, HU Binsheng, WU Yongfeng, XU Zhuo, RAO Yuping
    2014, 65(S1):  451-456.  doi:10.3969/j.issn.0438-1157.2014.z1.072
    Abstract ( 438 )   PDF (1297KB) ( 215 )  
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    A seed crystal coating machine dedicated for 800-1000 mm industrial stainless steel or ceramic tubular membrane support was developed. The machine adopt a coating method of spray and smear, seed crystal suspension was first spayed onto the rotating tubular support and then smeared evenly to form a thin film by inflated silicone rubber balloon. Combined with automatic control technology, the machine provided a solution for automatic seed crystal coating in process of zeolite membranes mass production. Main structure and working principle was introduced and the key factors affecting coating performance such as balloon hardness, balloon structure, balloon inflation pressure and moist state of seed crystal has been tested and analyzed. Production experiment of NaA zeolite sieve membrane with prototype has been conducted and the performance of products has been tested with 90% industrial alcohol at temperature of 75℃. Result showed the design was feasible and reliable, prototype coating speed was 30 products per hour and yield was above 98%; permeation flux of produced sieve membrane was 4-5.5 kg·m-2·h-1, water ratio of penetrating fluid was 99.2%-99.8%.