Comprehensive analysis of acid gases on mercury removal by CuCl2 modified char exposure to oxy-fuel environment: Experiment and XPS perception

Zeng Qingshan,Wang Hui,Wu Jingmao,Ran Hengyuan,Yang Kang,Wu Jianfei 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12

In this work, 0.15 mol/L CuCl2 solution was used to impregnate rice husk char. Experiments were conducted in a laboratory-scale fixed-bed reactor to investigate the oxidation mechanism of Hg0 by acidic gases. The effects of acid gases (SO2, HCl and NO) atmospheres on the mercury removal efficiency of the adsorbent were studied by FTIR, XPS and experiments. The FTIR results showed that the surface of the prepared rice husk char adsorbent contained a large amount of Cu2+ and chlorine-containing functional groups. The XPS results showed that the Cu+ on the surface of the adsorbent increased after mercury adsorption. This work shows that the inhibitory effect of SO2 on Hg removal is reflected in the blockage of the pore structure on the adsorbent surface; the competitive adsorption of O2 needed for the generation of C-O*, the formation of an acid mist by SO2 hinders the contact of Hg0 with the active site. The promotion of HCl is due to the production of active chlorine substances (Cl*) to promote the oxidation of Hg0 to HgCl, HgCl2 and HgO. And introduction of NO will react with O2, while generation of NO2 is beneficial to the oxidation of Hg0 to HgO and Hg(NO3)2. The optimum mercury removal efficiency of the adsorbent is nearly 100% under certain conditions.

ELECTRIC-HYDRAULIC COMPOUND CONTROL ANTI-LOCK BRAKING SYSTEM

Feng Yang,Xin Chen,Dong Guo,Mingmao Hu,Ziwen Liao,Zhongcheng Fu,Qingshan Gong 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.6

An anti-lock control strategy for electric-hydraulic compound braking is proposed to improve the emergency braking safety of a hub motor electric vehicle. Based on the half-vehicle braking longitudinal dynamics model, the optimal control is solved to obtain the total braking torque corresponding to each wheel. A fuzzy algorithm is used to determine the proportion coefficient of the motor based on the battery state of charge coefficient (SOC) and the motor speed constraints on the motor braking, and the total braking torque is distributed. The hydraulic and motor braking torques obtained from the allocation are input as reference values to the electric-hydraulic compound braking system, and the output braking torque is fed back into the CarSim vehicle model. The proposed electric-hydraulic compound ABS control strategy is also validated in the co-simulation of CarSim and MATLAB/Simulink on high, medium and low adhesion road surfaces.

Full-scale measurements of wind effects and modal parameter identification of Yingxian wooden tower

Bo Chen,Qingshan Yang,Ke Wang,Linan Wang 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.17 No.6

The Yingxian wooden tower in China is currently the tallest wooden tower in the world. It was built in 1056 AD and is 65.86 m high. Field measurements of wind speed and wind-induced response of this tower are conducted. The wind characteristics, including the average wind speed, wind direction, turbulence intensity, gust factor, turbulence integral length scale and velocity spectrum are investigated. The power spectral density and the root-mean-square wind-induced acceleration are analyzed. The structural modal parameters of this tower are identified with two different methods, including the Empirical Mode Decomposition (EMD) combined with the Random Decrement Technique (RDT) and Hilbert transform technique, and the stochastic subspace identification (SSI) method. Results show that strong wind is coming predominantly from the West-South of the tower which is in the same direction as the inclination of the structure. The Von Karman spectrum can describe the spectrum of wind speed well. Wind-induced torsional vibration obviously occurs in this tower. The natural frequencies identified by EMD, RDT and Hilbert Transform are close to those identified by SSI method , but there is obvious difference between the identified damping ratios for the first two modes.

Developments and applications of a modified wall function for boundary layer flow simulations

Jian Zhang,Qingshan Yang,Q.S. Li 한국풍공학회 2013 한국풍공학회지 Vol.17 No.4

Wall functions have been widely used in computational fluid dynamics (CFD) simulations and can save significant computational costs compared to other near-wall flow treatment strategies. However, most of the existing wall functions were based on the asymptotic characteristics of near-wall flow quantities, which are inapplicable in complex and non-equilibrium flows. A modified wall function is thus derived in this study based on flow over a plate at zero-pressure gradient, instead of on the basis of asymptotic formulations. Turbulent kinetic energy generation (GP), dissipation rate () and shear stress () are composed together as the near-wall expressions. Performances of the modified wall function combined with the nonlinear realizable k - turbulence model are investigated in homogeneous equilibrium atmosphere boundary layer (ABL) and flow around a 6 m cube. The computational results and associated comparisons to available full-scale measurements show a clear improvement over the standard wall function, especially in reproducing the boundary layer flow. It is demonstrated through the two case studies that the modified wall function is indeed adaptive and can yield accurate prediction results, in spite of its simplicity.

An alternative method for estimation of annual extreme wind speeds

Hui, Yi,Yang, Qingshan,Li, Zhengnong Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.2

This paper presents a method of estimation of extreme wind. Assuming the extreme wind follows the Gumbel distribution, it is modeled through fitting an exponential function to the numbers of storms over different thresholds. The comparison between the estimated results with the Improved Method of Independent Storms (IMIS) shows that the proposed method gives reliable estimation of extreme wind. The proposed method also shows its advantage on the insensitiveness of estimated results to the precision of the data. The volume of extreme storms used in the estimation leads to more than 5% differences in the estimated wind speed with 50-year return period. The annual rate of independent storms is not a significant factor to the estimation.

An alternative method for estimation of annual extreme wind speeds

Yi Hui,Qingshan Yang,Zhengnong Li 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.2

This paper presents a method of estimation of extreme wind. Assuming the extreme wind follows the Gumbel distribution, it is modeled through fitting an exponential function to the numbers of storms over different thresholds. The comparison between the estimated results with the Improved Method of Independent Storms (IMIS) shows that the proposed method gives reliable estimation of extreme wind. The proposed method also shows its advantage on the insensitiveness of estimated results to the precision of the data. The volume of extreme storms used in the estimation leads to more than 5% differences in the estimated wind speed with 50-year return period. The annual rate of independent storms is not a significant factor to the estimation.

Full-scale measurements of wind effects and modal parameter identification of Yingxian wooden tower

Chen, Bo,Yang, Qingshan,Wang, Ke,Wang, Linan Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.6

The Yingxian wooden tower in China is currently the tallest wooden tower in the world. It was built in 1056 AD and is 65.86 m high. Field measurements of wind speed and wind-induced response of this tower are conducted. The wind characteristics, including the average wind speed, wind direction, turbulence intensity, gust factor, turbulence integral length scale and velocity spectrum are investigated. The power spectral density and the root-mean-square wind-induced acceleration are analyzed. The structural modal parameters of this tower are identified with two different methods, including the Empirical Mode Decomposition (EMD) combined with the Random Decrement Technique (RDT) and Hilbert transform technique, and the stochastic subspace identification (SSI) method. Results show that strong wind is coming predominantly from the West-South of the tower which is in the same direction as the inclination of the structure. The Von Karman spectrum can describe the spectrum of wind speed well. Wind-induced torsional vibration obviously occurs in this tower. The natural frequencies identified by EMD, RDT and Hilbert Transform are close to those identified by SSI method, but there is obvious difference between the identified damping ratios for the first two modes.

Developments and applications of a modified wall function for boundary layer flow simulations

Zhang, Jian,Yang, Qingshan,Li, Q.S. Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.4

Wall functions have been widely used in computational fluid dynamics (CFD) simulations and can save significant computational costs compared to other near-wall flow treatment strategies. However, most of the existing wall functions were based on the asymptotic characteristics of near-wall flow quantities, which are inapplicable in complex and non-equilibrium flows. A modified wall function is thus derived in this study based on flow over a plate at zero-pressure gradient, instead of on the basis of asymptotic formulations. Turbulent kinetic energy generation ($G_P$), dissipation rate (${\varepsilon}$) and shear stress (${\tau}_{\omega}$) are composed together as the near-wall expressions. Performances of the modified wall function combined with the nonlinear realizable k-${\varepsilon}$ turbulence model are investigated in homogeneous equilibrium atmosphere boundary layer (ABL) and flow around a 6 m cube. The computational results and associated comparisons to available full-scale measurements show a clear improvement over the standard wall function, especially in reproducing the boundary layer flow. It is demonstrated through the two case studies that the modified wall function is indeed adaptive and can yield accurate prediction results, in spite of its simplicity.

Shape Effects on Aerodynamic and Pedestrian-level Wind Characteristics and Optimization for Tall and Super-Tall Building Design

Kim, Yong Chul,Xu, Xiaoda,Yang, Qingshan,Tamura, Yukio Council on Tall Building and Urban Habitat Korea 2019 International journal of high-rise buildings Vol.8 No.4

This paper reviews shape optimization studies for tall and super-tall building design. Firstly, shape effects on aerodynamic and response characteristics are introduced and discussed. Effects of various configurations such as corner modifications, taper, setback, openings, and twists are examined. Comprehensive comparative studies on various configurations including polygon building models, and composite type building models such as corner-cut and taper, corner-cut and taper and helical, and so on, are also discussed under the conditions of the same height and volume. Aerodynamic characteristics are improved by increasing the twist angle of helical buildings and increasing the number of sides of polygon buildings, but a twist angle of $180^{\circ}$ and a number of sides of 5 (pentagon) seem to be enough. The majority of examined configurations show better aerodynamic characteristics than straight-square. In particular, composite type buildings and helical polygon buildings show significant improvement. Next, shape effects on pedestrian-level wind characteristics around tall and super-tall buildings are introduced and discussed. Corner modification buildings show significant reductions in speed-up areas. On the other hand, setback and tapered models with wider projected widths near the ground show adverse effects on pedestrian-level wind characteristics.

Non-stationary and non-Gaussian characteristics of wind speeds

Hui, Yi,Li, Bo,Kawai, Hiromasa,Yang, Qingshan Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.24 No.1

Non-stationarity and non-Gaussian property are two of the most important characteristics of wind. These two features are studied in this study based on wind speed records measured at different heights from a 325 m high meteorological tower during the synoptic wind storms. By using the time-frequency analysis tools, it is found that after removing the low frequency trend of the longitudinal wind, the retained fluctuating wind speeds remain to be asymmetrically non-Gaussian distributed. Results show that such non-Gaussianity is due to the weak-stationarity of the detrended fluctuating wind speed. The low frequency components of the fluctuating wind speeds mainly contribute to the non-zero skewness, while distribution of the high frequency component is found to have high kurtosis values. By further studying the decomposed wind speed, the mechanisms of the non-Gaussian distribution are examined from the phase, turbulence energy point of view.