Volume 36,Issue 9,2013 Table of Contents

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  • 1  Experimental analysis of the evolution law of the coal seam gas permeability under long-term load
    XU Jiang YE Guibing LIU Dong LI Bobo CHENG Mingjun
    2013, 36(9):1-7. DOI: 10.11835/j.issn.1000-582X.2013.09.001
    [Abstract](1627) [HTML](296) [PDF 8.15 M](1411)
    Abstract:
    Gas-filled coal permeability evolution tests are carried out before and after the long-term load with temperature and effective stress changing by using the triaxial permeability equipment. Based on the experiments,temperature sensitivity coefficient and effective stress sensitivity coefficient of the permeability of the coal sample are analyzed before and after the long-term load. The experimental results are shown as follows:1)Before and after the long-term load,with the increase of effective stress,the permeability and effective stress sensitivity coefficient both decrease when the temperature keeps constant. At the same time,with the increase of temperature,the permeability and temperature sensitivity coefficient also decrease when the effective stress keeps constant;2)The difference of the permeability between before and after long-term load is different with temperature and effective stress changing,and it reflects thermal-fluid-solid coupling effect;3) Before and after the long-term load,the difference of temperature sensitivity coefficient first increases and then decreases with effective stress increasing,and it becomes negative when the effective stress is about 4.3 MPa. What’s more,the difference of effective stress sensitivity coefficient will decrease with the temperature increasing,and become negative after 26 ℃.
    2  Mechanism of crack-oriented of hydraulic fracture and its technique in mine
    XIA Binwei HU Ke LU Yiyu LIU Yong SONG Chenpeng
    2013, 36(9):8-13. DOI: 10.11835/j.issn.1000-582X.2013.09.002
    [Abstract](2681) [HTML](699) [PDF 7.25 M](1729)
    Abstract:
    Drainage is inefficient of coal seam treated by hydraulic fracture due to disordered propagation of fracture. Therefore, we propose a novel approach of fracture-oriented via slotting a slitting in coal seam by high pressure water jet. Firstly,boreholes-oriented are drilled around the borehole of hydraulic fracture. Then we slot the coal seam via high pressure water jet. Finally,we carry out hydraulic fracture in the borehole. Shear destruction area which is formed under geostress is located on crack tip. And crack propagates along horizontal direction because the major principal stress direction is horizontal. Besides,we develop the technique of crack-oriented and apply it in typical low permeability coal seam. The results show that the technique is efficient. The diameter of hydraulic fracture is larger than 25 m,the concentration of gas drainage is 68% on average,and the gas flow is 0.037 m 3/min. The concentration and flow of gas increase 2.12 times and 11.26 times respectively comparing to those of traditional technique.
    3  Experiment analysis on dissolution characteristics of rock salt on the effect of triaxial stress
    SONG Shuyi JIANG Deyi REN Song YANG Chunhe
    2013, 36(9):14-20. DOI: 10.11835/j.issn.1000-582X.2013.09.003
    [Abstract](2070) [HTML](590) [PDF 7.54 M](1550)
    Abstract:
    Rock salt underground storage is an important way of energy reserves. The research of rock salt dissolution characteristics under triaxial stress provides theoretical basis for shape control,security building of rock salt underground storage in the process of making aqueous cavity. The dissolution characteristics of rock salt specimens experiment with triaxial testing machine under triaxial stress,through a lot of rock salt dissolution tests,finds that dissolution characteristics of rock salt change remarkably under stress. Analyzing the relationship between the stress of rock salt specimen with the water hole and sample external axial compression or confining pressure,equivalent stress is adopted to describe the stress distribution of the running water hole wall. Triaxial stress and dissolution coupling experiment on the different confining pressure is carried out to analysis the variation between rock salt dissolution rate and equivalent stress under different confining pressures. The results show that rock salt dissolution rate decreases first and then rapid increases with the increase of equivalent stress. The main impact of the stress for rock salt dissolution rate is that cracks development and corrosion area in rock salt specimen are changed because of the triaxial stress loading. Dissolution rate reduces as a result of corrosion area decreasing (crack closure) in the elastic stage,however dissolution rate increases because of corrosion area increasing (crack development) in the plastic stage.
    4  Experiments on cleaning tunnels with dry ice
    REN Song HE Huayong JIANG Deyi CHEN Jie BAI Yueming
    2013, 36(9):21-27. DOI: 10.11835/j.issn.1000-582X.2013.09.004
    [Abstract](5159) [HTML](3577) [PDF 7.50 M](29098)
    Abstract:
    Vehicle exhaust,dust and grease in tunnels are hard to be degraded,thus there will be more and more pollutants and the traffic safety will be influenced. Therefore,regularly cleaning tunnels is important for guaranteeing the traffic safety in tunnels. A tunnel cleaning method with dry ice is proposed,and a model of dry ice cleaning tunnel is developed based on the physical,chemical and cleaning properties of dry ice. Some experiments about the surface hole,surface temperature and the uniaxial compressive strength of the concrete are conducted. The surface damage and the compressive strength of the concrete is researched after the cleaning process. The test results show that:the dry ice cleaning method can thoroughly clean the surface of concrete;the surface damage and the compressive strength is little influence by the temperature and dry ice micro blasting. So dry ice cleaning method can be used for cleaning tunnel.
    5  Experimental study on adaptability of well pattern using sandstone plate model with ultra-low permeability
    XIAO Qianhua YANG Zhengming XU Xuan TIAN Wenbo ZHANG Yapu
    2013, 36(9):28-34. DOI: 10.11835/j.issn.1000-582X.2013.09.005
    [Abstract](2028) [HTML](606) [PDF 8.90 M](1442)
    Abstract:
    Because the porous flow state is difficult to be simulated by one-dimensional cores and two-dimensional sand filled models,this paper proposes a method of making large-scale natural outcrop flat model and defines two parameters to evaluate adaptability of different well pattern on the ultra-low permeability sandstone flat model. With natural sandstone plate model,production of different well patterns in homogeneous oil reservoirs is simulated. A concept of pressure sweep efficiency and deliverability index for researches on adaptability of well patterns are put forward. Through experiments,plane pressure gradient field of different well patterns under different drawdown pressures are measured,and then seepage areas of the models are divided into immobilized seepage area,nonlinear seepage area,and quasi-linear seepage area,with the help of small core nonlinear seepage curve. Experiments show that adaptability of inverted nine-spot equilateral well pattern is better than those of inverted nine-spot rhombus well pattern and rectangular well pattern. With the increase of drawdown pressure,deliverability index of all well patterns increases,immobilized seepage area reduces,and quasi-linear seepage area expands. At the same time,nonlinear seepage area of inverted nine-spot equilateral well pattern reduces,while those of inverted nine-spot rhombus well pattern and rectangular well pattern fluctuate as expanding first and then reducing.
    6  Stability identification and application of goafs based on Dempster-Shafer theory
    HU Jianhua ZHANG Xingcheng ZHOU Keping DU Xianghui LEI Tao
    2013, 36(9):35-42. DOI: 10.11835/j.issn.1000-582X.2013.09.006
    [Abstract](1616) [HTML](603) [PDF 8.98 M](1464)
    Abstract:
    In the process of underground mining,as the effect of mining method and mining technology,massive goafs have been formed in underground mines,which is the main factor influencing the goafs stability in underground mining. Generally,there are four main factors to affect the goafs stability,i.e. structure parameters,space distribution features,stress environment and characteristic value,and geological condition and mechanical parameters of ore and rock mass. There are the sources of the stability identification of goafs based on the multiple source information. Based on CMS technology and engineering geology survey,numerical simulation technology,and using the AHP weight analysis,a D-S evidence classification model is built based on the multisource information fusion in the goafs stability. Take a mine as example,the mining information and the parameters are collected,and the classifications of goafs stability are identified according to a four grade classification method. The result shows that the stability is relative to the structure parameters,geological parameters and the stress environment parameters of goafs. It is a typical problem of the multisource information fusion. Using D-S evidence theory,the classification of the goafs stability is identified,and the results are consistent with the goafs stability in the engineering recognition. It is an effective approach to indentify the classification of the gaofs stability involving many factors.
    7  Research on a dynamic tracking model for reservoir water flooding of separated zone water injection
    WU Keliu LI Xiangfang LEI Zhengdong RUAN Min XU Hanbing FAN Zhaoqi
    2013, 36(9):43-51. DOI: 10.11835/j.issn.1000-582X.2013.09.007
    [Abstract](2110) [HTML](308) [PDF 11.22 M](1491)
    Abstract:
    Waterflood is one of the main oil reservoir development ways. Premature flooding of production wells during water flooding process will reduce oil recovery. Therefore,it is particularly important to establish a dynamic tracking model for reservoir water flooding of separated zone water injection. Based on the basic principles of heat and mass transfer,according to well temperature curve to determine the water profile,Poisson process analysis and stochastic process methods are adopted to calculate water saturation,water breakthrough time and water cut of each layer in water flooded reservoir at any one time. When oil reservoir gradually become water flooded,the calculated water cut of model considering micro-pore distribution of the reservoir tends to the measured water cut,and the calculation error is less than 5%. Case study shows that the layer of the higher injection rate,with high flow channel such as micro fracture,where there is the faster increase in water saturation,the shorter water breakthrough time and faster increase in water cut,and vice versa. Research result provides time guarantee to take measures for inhibiting or delaying water breakthrough of production wells.
    8  Experiments on variable mass flow in perforated completion horizontal wells
    WEI Jianguang WANG Zhiming ZHANG Quan GAO Xuezhen
    2013, 36(9):52-57. DOI: 10.11835/j.issn.1000-582X.2013.09.008
    [Abstract](1739) [HTML](489) [PDF 8.20 M](1735)
    Abstract:
    A considerable number of experimental work on the influence of flux ratio on variable mass flow in perforated completed horizontal wells has been published by many scholars,but the effects of perforation phasing,perforation diameter and perforation density on frictional,mixing and total pressure drop have not been studied systematically. In this paper,an experiment system is developed to investigate the influence of the perforation phasing,diameter and density. Three values of screw perforating phasing (45°,90°,180°),three kinds of perforation density (8 meter-1,16 meter-1,24 meter-1) and three sizes of perforation diameter (10 mm,20 mm,30 mm) are considered in the experiment of this paper. In the experiment,the Re (Reynolds number) of axial flow in pipe ranges from 1 000 to 20 000,the flux ratio (the ratio of the radial volume inflow at unit wellbore length to the axial volume flow in production pipe) ranges from 0.01% to 10%. The results indicate that:the frictional and total pressure drop increases while mixture pressure drop reduces with the increase of the perforation density and perforation diameter;the “mixing”,frictional and total pressure drop all increases with the increase of the perforation phasing;the proportion of frictional pressure drop to total pressure drop reduces while the proportion of “mixing” and acceleration pressure drop increases with the flux ratio;the “mixing” and acceleration pressure drop increases with the flux ratio,but there exists a critical value of flux ratio. When the actual flux ratio less than the critical value,the “mixing” pressure drop is negative,the acceleration pressure drop is almost 0 that induces the total pressure drop less than the frictional term. When the actual flux ratio is bigger than the critical value,the “mixing” pressure drop increases to positive,and the acceleration pressure drop increases with the flux ratio obviously.
    9  Reservoir characteristics of chromatographic effect of tracer flow in porous medium
    LIU Tongjing JIANG Baoyi LIU Rui ZHANG Xinhong XIE Xiaoqing
    2013, 36(9):58-63. DOI: 10.11835/j.issn.1000-582X.2013.09.009
    [Abstract](1769) [HTML](380) [PDF 7.21 M](1474)
    Abstract:
    Oil field practices have proved that the part of the interpretation model significantly deviated from the reasonable scope in interwell tracer interpretation. It is considered too single and unilateral,and can not adapt to the complicated seepage flow in porous medium and the quantitative description. Therefore,after completed the design of tracer microscopic visualized experiment and natural long core displacement experiment, we try to qualitative and quantitative analysis the tracer characteristics and propose the reservoir characteristic of chromatographic effect of the tracer flow. The tracer microscopic visualization experiments show that the foundation of reservoir characteristics of the chromatographic effect exists,that is small molecular tracers can enter the irreducible water,unconnected pores and low permeability clumps. The natural long core displacement experiment shows that water breakthrough and flowing around are significantly in the small size of non-homogenous natural long core,and reservoir characteristic of chromatographic effect is also significantly,the migration speed between water and tracer is bigger. That must be considered in interwell tracer interpretations. It has an extremely important guiding significance for quantitative interpretation and qualitative understanding of interwell tracer monitoring.
    10  Numerical simulation and water inrush risk evaluation for lower protective seam mining
    WANG Dengke WEI Jianping WEN Zhihui WANG Yungang
    2013, 36(9):64-70. DOI: 10.11835/j.issn.1000-582X.2013.09.010
    [Abstract](1432) [HTML](463) [PDF 8.58 M](1235)
    Abstract:
    In order to determine the safe width of fault waterproof coal (rock) pillar and solve the safety mining problem,the lower protective seam mining of a coal mine in Shanxi Province is taken as an engineering research object. Taking faults’ occurrence and throw into account,numerical tests with FLAC 3D numerical simulation software are conducted to investigate the development of mining-induced fractures in coal seam roof and floor,and the reasonable width of waterproof coal (rock) pillar is determinated through combining numerical simulation with empirical formula method. In addition,the risk evaluation of coal seam floor water inrush of No.6 mining area in this coal mine is finished using the result of numerical simulation. It is shown that fault is not only an important factor affecting the disturbance failure extent of coal seam floor in protective seam mining,but a key factor determining the safe width of waterproof coal (rock) pillar. In the risk evaluation of coal mine water inrush,the effect from mining-induced disturbance failure of coal seam floor should be considered.
    11  Study on global optimization control strategy of ISG velocity coupling hybrid electric vehicle
    YANG Yalian PU Bin HU Xiaosong YE Pan
    2013, 36(9):71-77. DOI: 10.11835/j.issn.1000-582X.2013.09.011
    [Abstract](2221) [HTML](337) [PDF 8.59 M](1413)
    Abstract:
    Hybrid system has the advantage of energy conservation and environmental protection. To improve the fuel economy of a hybrid system,based on the structure of the ISG velocity coupling HEV(hybrid electric vehicle),a dynamics simulation model is built. By using dynamic programming(DP) global optimization method,the variables of the engine throttle and the motor torque are set as the control variables,and the engine speed and the battery SOC are set as the state variables,the engine fuel economy is set as the objective function,and the battery SOC balance and the limited frequent shifting are set as the additional cost function. Then a global optimization program is built,and the simulation results indicate that the fuel economy of DP control HEV is 35.5% more efficient than that of the conventional vehicle.
    12  Trapping characteristics of low density polyethylene under DC ageing by space charge
    LIAO Ruijin NIE Shijun ZHOU Tianchun YANG Lijun YUAN Lei
    2013, 36(9):78-82. DOI: 10.11835/j.issn.1000-582X.2013.09.012
    [Abstract](2028) [HTML](579) [PDF 5.62 M](1590)
    Abstract:
    Space charge in insulation material of high voltage direct current cable is closely linked with the ageing degree of the materials,and it is an interesting topic if one can find some characteristics to indicate the ageing of the material from the space charge measurement. In this paper,the effects of ageing on space charge characteristics of low density polyethylene (LDPE) are investigated by the pulsed electro-acoustic (PEA) method. A space charge trapping model is proposed base on distribution of discrete traps,and the characteristic parameters in the model including trap depth and trap density are calculated. The results show that the relatively shallow traps in the samples transform to the relatively deep traps as the degree of electrical ageing increases. Furthermore,the relationships between ageing degrees and trap depth and trap density are obtained. The information of the trapping parameters in our model provides a good reference for diagnosing the ageing degree of polymeric materials.
    13  High impedance fault identification method of distribution network
    CHEN Minyou HUANG Yong ZHAI Jinqian
    2013, 36(9):83-88. DOI: 10.11835/j.issn.1000-582X.2013.09.013
    [Abstract](1815) [HTML](417) [PDF 7.99 M](1431)
    Abstract:
    High impedance fault is always difficult to be identified due to its unobvious fault signature and difficult detection. This paper decomposes the transient signal in multi-scale by utilizing the good localization performance of the wavelet in both time domain and frequency domain,reconstructs the wavelet coefficients under each scale,takes the wavelet reconstruction coefficient under the scale of 3,calculates the size spectrum of each feeder line in timing floating window and identifies the circuits in which the faults lined according to the value of the size spectrum. A high impedance fault simulation system is built based upon the study of the various transient signals in power systems,and the high impedance fault simulation analysis of the distribution feeder is undertaken through PSCAD simulation platform using high impedance fault model. Simulation analysis shows that the method can effectively extract the feature of high impedance fault on high impedance fault identification.
    14  Study on diagnostic method for defects in an IGBT module based on DTW deviations of time series
    ZHOU Shengqi ZHOU Luowei SUN Pengju
    2013, 36(9):89-95. DOI: 10.11835/j.issn.1000-582X.2013.09.014
    [Abstract](1620) [HTML](358) [PDF 7.72 M](1549)
    Abstract:
    Insulated gate bipolar transistor(IGBT) is one of the key reliability sensitive components of power electronic equipment. Developing prognostic method for defects in an IGBT module is an important measure to enhance the reliability lever of IGBTs. Therefore,a novel prognostic method based on dynamic time warping(DTW) deviations of time series is presented. This method utilizes variations of DTW of gate voltage series caused by defects to estimate if any defect existes in an IGBT module before breakdown. And application value is verified by test results.
    15  Measurement method for spray cooling characteristics of industrial nozzle
    OUYANG Qi LI Wanhong WU Chengbo
    2013, 36(9):96-100. DOI: 10.11835/j.issn.1000-582X.2013.09.015
    [Abstract](1816) [HTML](360) [PDF 7.88 M](1554)
    Abstract:
    In order to study the cooling characteristics of the nozzle, a test platform is designed and developed for spray cooling feature measurement based on unsteady state heat conduction. By heating and keeping Q215 metal samples up to some surface temperature, a series of temperature data are collected by S7-200 modules during spray force cooling. Through Visual C++6.0 and Matlab interface programming, a series of regression equation with thermodynamic property versus temperature, such as density, specific heat capacity, and thermal conductivity etc., and with temperature versus sample time are obtained. The surface heat transfer coefficient and spray cooling feature of nozzle can be indirectly measured by the regression equations. The relation between surface heat transfer coefficient versus temperature, spray pressure and water intensity are investigated by means of the testing equipment. The experiment result shows the method is feasible and can be used in spray cooling feature measurement for all kinds of nozzle.
    16  Microstructure and properties characteristic during interrupted multi-step aging(T6I6) in Mg-Zn-Mn alloy
    ZHANG Dingfei ZHU zengtao QI Fugang ZHAO Xiabing
    2013, 36(9):101-105. DOI: 10.11835/j.issn.1000-582X.2013.09.016
    [Abstract](1796) [HTML](689) [PDF 7.72 M](1131)
    Abstract:
    For researching the interrupted mutil-step aging techniques of Mg alloy, the effect T6I6 on microstructures and mechanical properties of the new alloy ZM61 is studied by XRD analysis, optional microscopy, electronic microscopy and EDS,TEM,hardness and machanical properties tests,etc. The results show that the T6I6 techniques, compared with T6, improve alloy strength more notably. The hardness of ZM61 after treated by T6I6 is 90HV, YS is 340MPa, UTS is 356 MPa, and the increased ratio of strength are 13% and 8% respectively. During the first step and second step of T6I6, only Mn continues to precipitate as α-Mn and forms more Mn simple particles. The grain boundaries of ZM61 alloy become clean during T6I6 treatment. The scope of strength increase sharply in third-step aging and the β precipitates distribute dispersively in the matrix while the strengthen effect been exerted drastically.
    17  Deformation behavior of alloy AZ31-0.5Sr-1.5Y at elevated temperature
    PENG Xiaodong LI Junchen YI Hongyu XIE Weidong WEI Qunyi
    2013, 36(9):106-112. DOI: 10.11835/j.issn.1000-582X.2013.09.017
    [Abstract](1704) [HTML](491) [PDF 9.06 M](1185)
    Abstract:
    The uniaxial hot compression test with Gleeble-1500D thermal simulator is performed on AZ31-0.5Sr-1.5Y alloy in the temperature range of 250-450 ℃ and stain rates of 0.01-1 s -1 with the maximum deformation degree of 0.85. The hot deformation behavior and hot workability of the alloy are studied. The constitutive equation and processing map of the alloy are established and studied by optical microstructure observation. The results show that the steady flow stress of AZ31-0.5Sr-1.5Y deforms at elevated temperatures can be described by the hyperbolic sine constitutive equation, and the activation energy is about 186.83 kJ/mol. After analyzing the hot processing map, at the true strain of 0.6, there is one unsafe deformation zone in the deformation temperature range of 250-300 ℃ and the strain rate range of 0.3-1 s -1. The optimal processing parameters obtained in the present work are the temperature range of 300-400 ℃ and strain rates of 0.01-1 s -1.
    18  Experiments on the preparation of Mn-Al master alloy by self-propagating high-temperature synthesis
    GAO Jiacheng ZHANG Yanke LI Ning CHEN Xiaohua HU De
    2013, 36(9):113-117. DOI: 10.11835/j.issn.1000-582X.2013.09.018
    [Abstract](1690) [HTML](313) [PDF 4.99 M](1361)
    Abstract:
    Self-propagating high-temperature synthesis(SHS) is applied to produce Mn-Al master alloy for the first time. The thermodynamic data of Mn-Al master alloy are estimated, and the adiabatic temperature is calculated by Miedema model and two-parameter model of intermetallics. The reaction product is investigated by using chemical titration optical microscope,X-ray diffraction analysis, in which Mn2O3, Mn3O4 and CaO are taken as raw materials and Al as a reductive agent. Theoretical calculation and experimental results show that the adiabatic temperature is 3 160 K,and the feasibility of the SHS reaction is determined consequently. The content of manganese in master alloy is up to 78%,which broadens the methods of producing Mn-Al master alloy in practice.
    19  Analysis of diffusion equation with the second and third boundary conditions based on steady state approximation
    WANG Chengshan HUANG Tailei MU Xiaojing
    2013, 36(9):118-126. DOI: 10.11835/j.issn.1000-582X.2013.09.019
    [Abstract](2235) [HTML](431) [PDF 11.22 M](1377)
    Abstract:
    One dimensional diffusion equation is widely used to describe mass transfer in particles or droplets in a reactor. The length of the definition domain of the one-dimension Fick equation is limited, because it is determined by the scale of the particles or the droplets. The diffusion equation with a certain length of definition domain has no analytic solution unless series solution. So, to obtain approximate solutions of diffusion equation is of theoretical significance and practical significance. Firstly, assumption of constant concentration variance ratio is used instead of assumption of constant concentration frequently used in kinetics of process metallurgy. Secondly, a detail process to deal with diffusion equation based on steady state approximation is given, and the approximate solutions of the diffusion equation at certain conditions are obtained at the same time. By comparing the approximate solutions with the numerical solutions, it is concluded that the diffusive process of non-steady state is considerably well predicted by the approximate solutions, and approximate solutions accord with the situations being close to the final steady state a little better than accord with the situations being close to the begin of the diffusion, and it fairly satisfies the total mass balance.
    20  Monitoring and deformation analysis of pushed landslide changing water level in the Three Gorges reservoir
    YI Pengying
    2013, 36(9):127-132. DOI: 10.11835/j.issn.1000-582X.2013.09.020
    [Abstract](1794) [HTML](511) [PDF 7.71 M](1251)
    Abstract:
    The typical pushed landslide deform becomes stronger when water fills in the Three Gorges reservoir. In order to better recognize the landslides deformation characteristics and prevent the disaster by the water change regulation, the paper takes an example of the features of geological conditions and deformation of Liangshuijing landslide in Yunyang which is the typical pushed landslide in the Three Gorges reservoir, and designs monitoring project. Through monitoring data including the surface displacement, ground fissure, deep displacement, ground water level, rainfall and macroscopic patrol, the variety law and relationship among monitoring data are obtained. The regularity of landslide deformation and its deformation velocity are concluded when the variation of the rainfall and water level change. Combined the variation of bands-stabilization coefficient, deformation laws of the pushed landslide by the rainfall or the reservoir water are obtained. The deformation caused by rainfall is large in the back landslide, while the deformation caused by hydrodynamic pressure is large in the front landslide. The higher the water level, the severelier of the influence. The deformation is largely influenced by hydrodynamic pressure when reservoir water declines sharply in the front landslide, and the deformation is the largest when rainfall and reservoir sharpe water decline happened simultaneously in the whole landslide. The law provides scientific basis for reduction and prevention disaster of the pushed landslide.
    21  Experimental investigation of electrothermal defrost tubes’ arrangement on heat transfer and flow resistance characteristics of evaporator
    WANG Houhua LI Dawei
    2013, 36(9):133-140. DOI: 10.11835/j.issn.1000-582X.2013.09.021
    [Abstract](1621) [HTML](643) [PDF 9.09 M](1291)
    Abstract:
    The paper presents new arrangement types of electrothermal defrost tubes and manufactures four evaporator samples. Through a wind tunnel refrigeration experimental test-bed, relatively experiments for every sample are carried to study heat transfer and flow resistances characteristics of evaporator. The experiment results show that in experimental face velocity range from 1.5 m/s to 4.3 m/s compared with flat-fin evaporator, the unit area of cooling capacity of DK-8 evaporator increased 28.1% to 36.2%, the fin surface coefficient of heat transfer raises 79.2% to 83.5%, the compressor COP (Coefficient of Performance) improves 38.2% to 46.9%, and the air side flow resistance decreases 5.29% to 18.3% in the same experimental condition and geometric size. The increase amplitude of COP is obviously higher than air side flow resistance. The experimental investigation results prove that it is completely feasible optimized combing defrost design with heat transfer enhancement design.
    22  Purification and characterization of the extracellular algae-lysing components from an algae-lysing bacteria
    WANG Jinxia LUO Guyuan YE Jiangyu XU Xiaoyi LIU Jing
    2013, 36(9):141-145. DOI: 10.11835/j.issn.1000-582X.2013.09.022
    [Abstract](1630) [HTML](536) [PDF 5.92 M](1548)
    Abstract:
    Purification, characterization and initial identification of extracellular algae-lysing constituents of fermentation products of the algicidal bacteria S7 are carried out by ultraviolet spectrum, infrared spectrum, fluorescence spectra and mass spectrum, and the results show that the eluates of methanol have the best algicidal effects. These active algicidal substances made of conjugation unsatuated bonds, hydroxyl, saturated alkyl and aromatic ethers. In the three-dimensional fluorescence spectroscopy, two strong fluorescence peaks appear at 264/436 nm and 378/369 nm respectively. Mass spectrum indicates that the active substances consist of six monomers, and their molecular weights are 163.1, 246.3, 274.3, 318.3, 404.5 and 475.4, respectively.
    23  Analysis on Cd 2+ adsorption capability of activated carbon modified by HNO3
    WANG Weiwen ZHANG Tao LU Jingke DING Chunsheng
    2013, 36(9):146-150. DOI: 10.11835/j.issn.1000-582X.2013.09.023
    [Abstract](1886) [HTML](352) [PDF 5.05 M](1427)
    Abstract:
    In order to improve the absorption ability of Cd 2+, the activated carbon is modified by HNO3. Additionally, the structure changes of activated carbon with and without treatment are studied in virtue of BET, Boehm and other instruments. The research demonstrates that the specific surface area and the number of activated carbon surface functional groups dramatically change after treatment, and the specific surface area and the figure of acid functional groups after HNO3 oxidizing increase. It is worth mentioning that under the condition of pH with 7.00, the removal rate of Cd 2+ by raw activated carbon is approximately 10%, in contrast, the removal efficiency reached 41% by 10% N-GAC and 57% by 70% N-GAC, the removal effects of Cd 2+ could be improved after modification. With the dosing quantity of modified activated carbon increased, the removal effects of Cd 2+ are also increased. PH is the biggest influence factor of removing Cd 2+. As the pH of solution increases, the removal rates of three kinds of adsorbent for Cd 2+ increases. Adsorption kinetic research shows that the adsorption reaction of Cd 2+ on 10% N-GAC is suitable to Lagergren pseudo-first-order (PFO) reaction in the former 20 min and more suitable to Lagergren pseudo-second-order (PSO) reaction after 20 min.
    24  Necessity of shading on north facade and optimal selection of shading device
    TAO Qiuhua LI Zhengrong JIANG Fujian HU Lingzhou
    2013, 36(9):151-158. DOI: 10.11835/j.issn.1000-582X.2013.09.024
    [Abstract](1936) [HTML](473) [PDF 8.73 M](1608)
    Abstract:
    This research is aimed at exploring the necessity of shade on the north facade and optimal selection of shading device. Firstly, the direct and diffuse solar radiation distribution on the surface of each orientation is analyzed in the air conditioning period in Shanghai and Xiamen. Secondly, the simulated building model is established to analysis the impact of different external shades on solar radiation heat gain and day-lighting with Energy-plus. These shades include fixed overhang of different dimensions, roller with different properties and louver of different slat angles. The glare index of different shade devices is also analyzed, results show that the hours exceeding the glare index set point of the fixed overhang and roller are far more than louver’s. Finally, the impact of different external shades on lighting energy consumption and air conditioning energy consumption on the north facades is analyzed. Results show that the use of medium-reflect and medium-transmit external roller is the most energy-saving in Shanghai, the effect of adjustable external blind is close to the roller, and the effect of fixed overhang is not obvious. In Xiamen, the use of adjustable external blind is the most energy-saving, the next is roller, and the last is fixed overhang. Taking energy-saving and glare into consideration, adjustable louver is the best choice of shade on the north facade in Shanghai and Xiamen.

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