Volume 41,Issue 12,2018 Table of Contents

1 Simulation of shear-thinning droplets impact on solid surfaces by using Lattice Boltzmann method

ZHOU Ping , ZENG Zhong , QIAO Long

2018, 41(12):1-9. DOI: 10.11835/j.issn.1000-582X.2018.12.001

[Abstract](1061) [HTML](455) [PDF 1.02 M](807)

Abstract:
The droplet spreading and deposition appear widely in industrial applications, and it is of practical significance to study the effect of non-Newtonian rheology on droplets impact on solid surfaces. In this research, we developed a two-phase lattice Boltzmann model based on the phase field method for power-law fluid flows. By introducing a contact angle condition, power-law droplets impact on solid surfaces was investigated, and the effects of power exponent n (0.5 ≤ n ≤ 1.0) and Weber number We (5 ≤ We ≤ 45) on shear-thinning droplets impact were evaluated. The results indicate that power-law liquid inhibits the droplet spreading and splashing, and it becomes easier for deposition with the decrease of n. In addition, droplets are easier to reach stationary state as weber number increases.

2 Influence of diffusion area on gas emission characteristics of coal specimens

ZHAO Hongbao , WANG Hongbing , ZHANG Huan , WEN Zhijie

2018, 41(12):10-19. DOI: 10.11835/j.issn.1000-582X.2018.12.002

[Abstract](730) [HTML](409) [PDF 4.12 M](905)

Abstract:
In order to study the influence of diffusion area on gas emission characteristics, the self-made briquette specimens were taken as the research object. The test was done through sealing coal briquette surface with the self-developed briquette specimens gas emission test device. The results show that the influence of the diffusion area on the gas emission rate of the briquette decreases with the decrease of the diffusion area, but the gap between the values of velocity reduction is gradually narrowed with the extension of the dispersion time. The dispersion velocity curve is approximately L-shaped as a whole, but there is a velocity "transcendence" phenomenon at the inflection point. And it is found that the influence of the two opposite sides of the sealed briquette on the emission velocity is greater than that of the two adjacent faces of sealed briquette and the influence of the diffusion area on the gas emission of the briquette shows that the relation between the cumulative discharge and the time in different diffusion areas is still a finite monotonic increasing function. However, in the same period of time and under different gas pressures, the cumulative discharge is reduced with the derease of the area of briqutte.

3 Characterizations of phosphorus fractions in the soil at different altitudes of water-level-fluctuation zone,Three Gorges Reservoir

FANG Bo , WANG Chao , WANG Chong , ZHOU Xiaoming , FANG Fang , GUO Jinsong , LI Zhe

2018, 41(12):20-29. DOI: 10.11835/j.issn.1000-582X.2018.12.003

[Abstract](847) [HTML](407) [PDF 733.17 K](799)

Abstract:
The concentrations of different phosphorus fractions in the soils obtained in the Water-Level-Fluctuation Zone (WLFZ) of the Pengxi River Basin, Three Gorges Reservoir were analyzed. In addition, correlations between these concentrations and different physical-chemical characteristics of the soil samples were also analyzed. The results indicate that the average concentration of total phosphorus (TP) is 599.00 mg/kg. And both the TP and inorganic phosphorus(IP) concentrations gradually decrease with the decrease of altitude. The concentrations of active phosphorous(Ac-P) in the soils of the WLFZ significantly less than those of the riverside at the altitude of 180 m, Ac-P concentrations at the elevation of 155 m, 145 m are close to those of the sediment at the elevation of 140 m but lower than the concentration detected in the samples obtained at the altitude of 165 m. The distribution of Ac-P concentrations at different altitudes indicate that the frequent dry-wet alternations result in the loss of Ac-P in the soils. There is a significent negative correlation between the pH and the TP, IP and Ca-P, meaning the increase in pH result in the decrease in TP, IP and Ca-P, and the organic matter concentration is positively correlated with the organic phosphate concentration, indicating that the input of organic matter affected the concentration of organic phosphate.

4 The establishment of the low frequency mode in piedmont complex lithology area

HUANG Cheng , LI Pengfei , CHEN Yuanyong , YANG Xianzhang , ZHANG Wei

2018, 41(12):30-35. DOI: 10.11835/j.issn.1000-582X.2018.12.004

[Abstract](744) [HTML](436) [PDF 3.70 M](977)

Abstract:
The accurate exploration of piedmont complex reservoir is a major problem in geophysical exploration. It's difficult to analyze and predict the distribution law of reservoir sand bodies in piedmont zone because of its complex structural features, rapid formation of lithology and unclear geological structure. In this paper, the importance of low frequency model to the inversion results is studied by taking wedge model in homogeneous medium as an example. And to solve the exploration problems in Shenmu area of Tarim basin of Cretaceous Shushanhe Formation sandstone, we proposed a new method for constructing low frequency model of piedmont complex geological body by using velocity body and attribute body which reflects the sedimentary tendency to supplement the very low frequency (0 to 3 Hz) components, and by using well interpolation model which is controlled by tectonic horizon to supplement 3 Hz to 10 Hz frequency. The method has achieved good results in the evaluation of the target oil and gas exploration in the Kuche foreland basin.

SHI Feng , WANG Hongtu , SHU Cai

2018, 41(12):36-45. DOI: 10.11835/j.issn.1000-582X.2018.12.005

[Abstract](759) [HTML](344) [PDF 2.02 M](754)

Abstract:
To get insight into the swelling and displacement law with seam dip angles change, similar simulation studies of gentle dip, dip and steep dip angles were conducted. The experiment angles and geometrical properties were chosen from a particular coal seam of various dip angles in Nantong Mining District. Digital speckle correlation method was used in the result analysis to quantitate the overburden strata deformation for the displacement and the total plane strain contour maps. Further analysis of the plane strain and displacement distribution gives the following major findings:generally the swelling and displacement condition will be relieved and the corresponding intense regions will rise to the upper boundary with the increase of seam angle; Based on the morphology in both contours, the interfaces of "Three Zones" were determined in the position of maximum value of contour, as well as height of caving zone and fractured zone and the eccentric degree in seam angle of gentle dip and dip; In the dip angle condition, stress arch-shell theory is used to determine height of fractured zone. Quantitative characteristic parameters show the distributions of caving zone and fractured zone are biased toward upper boundary while both heights exhibit a decrease trend.

6 Response surface methodology study on optimal modification conditions for Ni(Ⅱ) adsorption in the water by peanut shell carbon

AN Qiang , JIANG Yunqiu , WU Danqing , CHEN Xuanbing

2018, 41(12):46-54. DOI: 10.11835/j.issn.1000-582X.2018.12.006

[Abstract](825) [HTML](376) [PDF 3.57 M](750)

Abstract:
To improve the removal efficiency of nickel in the water and obtain a kind of adsorbent with low-cost and high efficiency, peanut shell carbon derived from waste peanut shell was produced and modified by potassium permanganate(KMnO₄) and potassium(KOH). Box-Behnken design and response surface methodology were used to optimize the modification conditions of the carbon. SEM and BET were employed to characterize the morphological and structural changes of the peanut shell carbon before and after the modification. The modified peanut shell carbon before and after Ni(Ⅱ) adsorption was analyzed by FTIR to preliminarily discuss its adsorption mechanism. The results show that the best modification conditions are:temperature 361℃, the mass ratio of KOH to carbon 2.5 and the concentration of KMnO₄ 0.76%. Under these best modification conditions, the maximum adsorption capacity of nickel is 85.02 mg/g, which is 15.6 times higher than that of the carbon without modification, proving its superior adsorption performance and pragmatic value. The results of FTIR show that -OH and -NH₂ are the main functional groups in the Ni(Ⅱ) adsorption process and they participate in the co-precipitation and complexation reactions with Ni(Ⅱ). Besides, the effect of cation-π is also one of the adsorption mechanisms of modified peanut shell carbon to Ni(Ⅱ).

7 Study on emission characteristics and field measurement of PM_2.5 in coal-fired power plant boilers

YANG Jianjun , DU Lilao , MA Qixiang , LIN Qicai , LU Lidong , LIU Zhaomei , XU Nan , SHEN Yuanyuan

2018, 41(12):55-65. DOI: 10.11835/j.issn.1000-582X.2018.12.007

[Abstract](711) [HTML](368) [PDF 911.88 K](798)

Abstract:
Field experiments and chemical composition analysis of particle in flue gas from several coal-fired power plants in Guanzhong area of Shaanxi province was carried out with dilution and collection system of PM_2.5 in stationary sources designed by the team. The results show that the proportions of PM_2.5 and PM₁₀ in the particles of 4 coal-fired power plants are quite different. The proportion of PM_2.5 ranges from 6.92% to 54.34%, and the proportion of PM₁₀ ranges from 36.36% to 73.02%. Maximum values (2.0×10⁴ to 4.0×10⁵/cm³) of number concentration levels from 4 coal-fired power plants are quite different, and the difference is about 1 order of magnitude. The mass concentration proportion of small particles to PM_2.5 from coal-fired power plants is mostly low, but the small particles' contribution to PM_2.5 number concentration is great (minimum value > 95%), and the situation of the large particles is quite the opposite. The PM₁/PM_2.5 value of the pulverized coal boiler is large, the ratio range is between 35.29% and 51.35%, and the PM₁/PM_2.5 value of the circulating fluidized bed boiler is small, the ratio range is between 16.62% and 21.47%. SO₄^2- is the most abundant ion component in PM_2.5 of coal-fired power plants, and the proportion of SO₄^2- to total ion concentration ranges from 50.02% to 65.52%, Na⁺ and Ca²⁺ ranking second or third. The main inorganic elements detected in the coal-fired power plants are Si, Al, Ca, Na, Fe, Na and other crustal elements. The emission factors' range of PM_2.5, PM₁₀ and particles in the coal-fired power plants are 0.001 to 0.028 kg/t, 0.002 to 0.086 kg/t and 0.003 to 0.236 kg/t, respectively. The more complex and advanced the combination of dust removal facilities is, the smaller the emission factor is likely to be.

8 Research on the strategy of electric vehicles participating in power system frequency control based on SOC

LI Hongyu , SHE Chao , ZHANG Tingjun , LUO Wenbin

2018, 41(12):66-72. DOI: 10.11835/j.issn.1000-582X.2018.12.008

[Abstract](850) [HTML](409) [PDF 465.78 K](1069)

Abstract:
A large number of unmanaged electric vehicles (EVs) connected to the power grid brings harm to the safety of the power system. By using the technology of V2G, EVs are connected to grid to participate in the system frequency modulation. However, the demand of batteries will be affected. In this research, by analyzing the distribution of probability density of EV battery state, the strategy of participating in system FM control considering battery state of charge was proposed. Based on the characterristics of battery of EVs, a model was built. The EV charging and discharging scenario, which aims at stability of the frequency fluctuation of the power grid, was simulated. According to the state of SOC of the battery, the simulation results based on the control strategy of Matlab/Simulink verify the actual effect of EV participating in the system frequency modulation.

9 Distributed economic dispatch method for microgrids based on the equal incremental cost criterion

XU Ruilin , YANG Yun , LI Junjie , LIAO Yuexi , XIA Haibo , CHEN Minyou

2018, 41(12):73-82. DOI: 10.11835/j.issn.1000-582X.2018.12.009

[Abstract](851) [HTML](490) [PDF 3.59 M](1125)

Abstract:
To achieve the minimal operation cost of microgrids(MGs), a distributed economic dispatch method was proposed, in which a two-layer model was used. The upper layer is a communication network for information transmission, while the lower layer is a MG for power transmission. The communication network consists of two sub-networks, one of which is composed of all agents while the other is only composed of controllable agents. Then construction rules of communication network was established, and a general method was systematically given to derive distributed control laws from any communication networks. The distributed control laws derived from the first sub-network ensure the supply-demand balance, while the distributed control laws derived from the second sub-network minimize the cost of power generation, thus realizing the consensus of incremental cost of all the controllable DGs via the iteration of controllable agents. Based on equal incremental principle, the minimal operation cost of all controllable DGs was obtained. Finally, two simulation cases were designed to evaluate the performance of the method. The simulation results show that the proposed method can realize the minimal operation cost of MGs when the loads and renewable resources fluctuate widely.

10 Optimal configuration of distributed generation considering probability power flow

ZHANG Zhongwei , WANG Jinyu , ZHANG Jianbo , YANG Yang

2018, 41(12):83-91. DOI: 10.11835/j.issn.1000-582X.2018.12.010

[Abstract](777) [HTML](411) [PDF 501.25 K](963)

Abstract:
In order to solve the problem caused by paralleling operation of electric vehicles and distributed power grids, which brings strong randomness, intermittent and correlation to power system. Based on the probabilistic model of distributed power supply and electric vehicle, an optimal configuration model taking distributed power supply total cost, power supply reliability and active network loss as the objective function was established, embeding the probabilistic power flow calculation into the adaptive parameter difference based on the success history. The evolutionary algorithm was used to solve the objective function. The unscented transformation was used to describe the statistical properties of the system state variables by using the mean and covariance of the input random variables to directly deal with the random variables with uncertainty. Then RBF neural network was used to solve the power equation, which avoided calculating the Jacobian matrix and partial derivative, reducing the running time of the algorithm. Finally, the multi-objective function was calculated in parallel using the adaptive parameter differential evolution method based on the success history. The simulation of the IEEE33 node power distribution system verified the effectiveness and efficiency of the method and the method can save planning costs.

11 Progress in the research on anode material Li₄Ti₅O₁₂ for Li-ion batteries

YOU Shili , FANG Ling , XU Haitao , WANG Yu

2018, 41(12):92-100. DOI: 10.11835/j.issn.1000-582X.2018.12.011

[Abstract](771) [HTML](0) [PDF 5.59 M](391)

Abstract:
The material Li₄Ti₅O₁₂ with its advantages of stability, safety, long life, etc., has been the research focus of anode material for lithium ion batteries. In this paper, the structural features and energy storage mechanism of Li₄Ti₅O₁₂ were introduced. The solid state method, microwave method, sol-gel method and other preparation methods of Li₄Ti₅O₁₂ were discussed and summarized. And some modification methods of Li₄Ti₅O₁₂, such as ion doping, surface coating and morphological control, were summarized and reviewed as well. Finally, the prospects for the development of Li₄Ti₅O₁₂ were discussed.

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