Key Laboratory of Coal Science and Technology

Taiyuan, China

Key Laboratory of Coal Science and Technology

Taiyuan, China
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Lei Y.,Taiyuan University of Technology | Zheng F.,Taiyuan University of Technology | Song C.,Taiyuan University of Technology | Lyu Y.,Key Laboratory of Coal Science and Technology
International Journal of Heat and Mass Transfer | Year: 2017

A new circular tube with delta-winglet vortex generators is proposed in order to improve the thermal hydraulic performance for energy conservation. The delta-winglet vortex generators are punched out from the fin which inserted in the center of the circular tube. Three-dimensional numerical investigation is performed to study the thermal hydraulic characteristics of the circular tube with delta-winglet vortex generators. The effects of attack angle (β = 15 deg, 30 deg, 45 deg, and 60 deg) and pitch (P = 1D, P = 2D, P = 3D, and P = 4D) of delta-winglet vortex generators on heat transfer and fluid flow are examined in detail. The mechanism of heat transfer enhancement is analyzed based on the viewpoint of field synergy principle. The results demonstrate that delta-winglet vortex generators generate swirling motion of flow to enhance the fluid flow mixing in circular tube resulting in heat transfer augmentation with a moderate pressure drop penalty. It was found that the Nusselt number increase with the increasing attack angle and decreasing pitch of the delta-winglet vortex generators. The mechanism of heat transfer enhancement in circular tube by using delta-winglet vortex generators can be well explained by field synergy principle. © 2017


Li Y.-Z.,Taiyuan University of Technology | Lei Y.-G.,Taiyuan University of Technology | Lu Y.-K.,Key Laboratory of Coal Science and Technology | Jing S.-L.,Taiyuan University of Technology | Wang F.,Taiyuan University of Technology
Gao Xiao Hua Xue Gong Cheng Xue Bao/Journal of Chemical Engineering of Chinese Universities | Year: 2017

Shell side flow in traditional segmental baffle heat exchangers has large dead zone, which leads to the decrease of heat transfer area and increase of resistance loss. In order to improve heat transfer efficiency of segmental baffle heat exchangers, a novel louver baffle supported tube bundle configuration was proposed. The heat transfer and flow resistance of confined external flow within louver baffle supported tube bundles were investigated by three-dimensional numerical simulation. The results show that the flow field is uniform and has less dead zone. Compared with shell-side confined external flow, pressure drop of the proposed confined external flow decreases by 17.1%~45.7%, which greatly improves energy consumption. Moreover, the pressure drop decreases with the decrease of inclination angle, with the best overall performance at 45°. The maximum heat transfer coefficient of the new confined external flow is 25.9% higher than that supported by segmental baffles under same pressure drop. This study can help the design and development of shell and tube heat exchangers with low power consumption. © 2017, Editorial Board of “Journal of Chemical Engineering of Chinese Universities”. All right reserved.


Lei Y.,Taiyuan University of Technology | Li Y.,Taiyuan University of Technology | Jing S.,Taiyuan University of Technology | Song C.,Taiyuan University of Technology | And 2 more authors.
Applied Thermal Engineering | Year: 2017

Two novel shell-and-tube heat exchangers with louver baffles are invented and designed for energy conservation. A certain amount louver baffles at the inclination angle between shell side flow direction and louver baffle are equipped in shell side to support tube bundles. Numerical simulations are carried out to investigate the thermo-hydraulic performance of the two reformed shell-and-tube heat exchangers with louver baffles. For comparison, a shell-and-tube heat exchanger with conventional segmental baffles also studied in the paper. Fluid flow structures and temperature distributions are presented for the analysis of the physical behavior of fluid flow and heat transfer. Oblique flow is produced in the shell side of the shell-and-tube heat exchangers with louver baffles that decrease and eliminate the dead spaces and augment the local heat transfer. Compared with the shell-and-tube heat exchanger with segmental baffles, abrupt change of fluid flow is avoided that decrease the pressure drop in the shell side. The numerical results indicated that the heat transfer coefficient per pressure drop of both the shell-and-tube heat exchangers with louver baffles are higher than that of the shell-and-tube heat exchanger with segmental baffles. This implies that at the same heat transfer quantity, the pumping power of the shell-and-tube heat exchangers with louver baffles is lower than that of the shell-and-tube heat exchanger with conventional segmental baffles. © 2017


Zuo Z.-J.,Key Laboratory of Coal Science and Technology | Li J.,Key Laboratory of Coal Science and Technology | Han P.-D.,Taiyuan University of Technology | Huang W.,Key Laboratory of Coal Science and Technology
Journal of Physical Chemistry C | Year: 2014

To better understand the autoxidation mechanism of Cu-based catalysts, we studied the oxidation of Cu sheet exposed to ultrahigh vacuum and air at ambient temperature using X-ray photoelectron spectroscopy (XPS) and density functional theory. Six main stages of Cu autoxidation are revealed: (1) dissociative adsorption of O2, (2) coexistence of nondissociative and dissociative H2O adsorption, (3) diffusion of O and OH into Cu bulk, (4) formation of metastable Cu2O layer, (5) further oxidation and formation of metastable Cu(OH)2 and CuO layer, and (6) transformation phase of the metastable Cu(OH)2 to CuO. The formation of Cu(OH)2 depends on the relative humidity of air and the concentration of adsorbed OH of the Cu sheet. On the basis of these results, we propose that the preservation time of the Cu-based catalysts should be decreased or the catalysts should be preserved in a high vacuum and at low relative humidity. Considering the time of the sample preparation before ex situ XPS analysis and other surface characterizations, the Cu-based catalysts need to be etched by ∼10 s using an Ar ion gun. These findings serve as a guide for the preservation and preparation of Cu-based catalysts before actual measurement. © 2014 American Chemical Society.


Luan C.,Key Laboratory of Coal Science and Technology | Luan C.,Taiyuan University of Technology | Zhang A.,Taiyuan University of Technology | Wang X.,Key Laboratory of Coal Science and Technology | And 2 more authors.
Indian Journal of Chemistry - Section A Inorganic, Physical, Theoretical and Analytical Chemistry | Year: 2012

Cu-Zn-Al catalyst prepared by a complete liquid phase technology for CO hydrogenation has been investigated in a fixed bed reactor in terms of catalytic performance and compared with catalysts prepared by a traditional method such as co-precipitation. The catalysts are characterized by XRD, NH3-TPD, H2-TPR and XPS. Results show that the activity of the liquid phase prepared catalyst is much lower in fixed bed reactor than in a slurry reactor. It was also much lower than that of the catalyst prepared by co-precipitation, although its stability is higher. XPS and XRD characterization reveal that there are obvious differences in the structure, morphology and surface state of the catalysts prepared by the two methods. In the catalyst prepared by liquid phase technology, Cu exists in the form of metallic Cu even though the catalyst is unreduced and there are more acid sites and more carbon on its surface than on the surface of the co-precipitation catalyst. It is concluded that there is a surface carbon film covering the liquid phase catalyst, and the carbon film is an important reason for the low activity when the catalyst is applied to fixed bed reactor. Coke burning off, an effective way for removing the surface carbon, improves the catalyst activity in a fixed reactor.


Dong X.Q.,Taiyuan University of Technology | Dong X.Q.,Key Laboratory of Coal Science and Technology | Dong X.Q.,Seoul National University | Yang G.-H.,Taiyuan University of Technology | And 2 more authors.
Fresenius Environmental Bulletin | Year: 2012

The alternating current (AC) impedance characteristics of silty soil samples have been studied by measuring their AC impedance parameters within the frequency range of 50-10 6 Hz. The parameters include the real part Z′, imaginary part Z″, impedance module |Z|, and phase difference θ. The effects of the frequency f and the water content w on these parameters are analyzed. The electrical resistivity ρ s of silty soil is also calculated, and the relational expression between ρ s and w is fitted. Finally, a predication formula of soil w is developed using ρ s and f The results indicate that Z′, -Z″, and |Z| decrease with increasing logarithm of frequency, log f, and w. Also, θ increases with increasing log f, and 6 does not change with w, except at f= 50 and 10 2 Hz. Given the strong relation of Z′ with w, Z′ of silty soil is primarily determined by the polarizability of free water. In contrast, Z″ of silty soil mainly represents loss from conduction. |Z| is affected by the polarizability of free water and conduction loss. θ shows the capacitance of the silty soil. At every f an exponential function is used to simulate soil w increase with decreasing ρ s, which has a very high correlation coefficient. Calculated by the predication formula, w is very close to the true w, indicating the reliability of the formula. © by PSP Volume 21 - No 2a. 2012.


Lu Y.,Key Laboratory of Coal Science and Technology | Yin J.,Key Laboratory of Coal Science and Technology | Liu Y.,Taiyuan University of Technology | Zhang W.,Key Laboratory of Coal Science and Technology
Huagong Xuebao/CIESC Journal | Year: 2011

A heterotrophic nitrifier with high efficiency of removing NH4 +-N and significant accumulation of NO2 --N, named strain C16, was isolated from the activated sludge of a cokes wastewater treatment facility . Cells of strain C16 were Gram negative, short rods. The colonies were translucent white. It was identified as Alcaligenes sp. according to its morphological and physiological properties and the analysis of its 16S rRNA gene sequence. Results show that all NH4 +-N have been removed. The removal rate of NH4 +-N by this strain is 94.7% and the accumulation of NO2 --N is tremendous in the optimization medium after 4 d cultivation through the experiment of medium optimization. The concentration of NO2 --N is up to 30.1 mg·L-1 compared with the counterpart original cultivation which is just 7.34 mg·L-1. © All Rights Reserved.


Dong X.,Taiyuan University of Technology | Dong X.,Key Laboratory of Coal Science and Technology | Dong X.,Seoul National University | Woo H.,Seoul National University | And 2 more authors.
Environmental Earth Sciences | Year: 2013

To verify the applicability of the time-continuous electrical conductivity (EC) measurement in analyzing the contaminant movement in the subsurface, a new column test device employing non-destructive four-electrode sensors was developed. Using the seawater to create a simple one-dimensional steady-flow condition, laboratory transport experiments were conducted and the EC breakthrough curves at different distances were obtained. Comparison between the EC breakthrough curves obtained from the EC sensors and those from the effluent solute chemical analysis showed that the estimated resident concentration from the EC breakthrough curves are useful in understanding solute transport in soils. The pore water velocity and longitudinal dispersion coefficient estimated using the computer code, CXTFIT, were found to be slightly underestimated, especially at sensors located at smaller distances from the outlet boundary. Results showed that the developed column test device employing the four-electrode sensors proposed in this study provides a non-destructive, convenient, and inexpensive means of evaluating the seawater transporting in soils. © 2013 Springer-Verlag Berlin Heidelberg.


Dong X.,Taiyuan University of Technology | Dong X.,Key Laboratory of Coal Science and Technology | Dong X.,Seoul National University | Liu X.,Taiyuan University of Technology | And 2 more authors.
Environmental Earth Sciences | Year: 2014

To obtain the breakthrough curves without efforts required in the sampling and chemical analysis, a new soil column test device was developed. The device can conduct time-continuous electrical conductivity (EC) measurements without disturbing the soil matrix at all stages of the test. This device is composed of soil column, channel selector, LCR meter, and data logger. The soil column employs three 4-electrode sensors installed at different positions. To verify its applicability, the electrical conductivity breakthrough curves at different distances have been obtained with the use of five different species influent solutions (KCl, NaCl, CaCl2, MgCl2, and seawater). Results showed that the EC breakthrough curves and the transport parameters (the pore-water velocity, the dispersion coefficient, and the dispersivity) are very reasonable, and understand the one-dimensional steady flow exactly. The developed soil column test device proposed in this study provides a nondestructive, convenient, and inexpensive means of obtaining EC breakthrough curves. © 2014, Springer-Verlag Berlin Heidelberg.


Zuo Z.-J.,Key Laboratory of Coal Science and Technology | Han P.-D.,Taiyuan University of Technology | Hu J.-S.,Key Laboratory of Coal Science and Technology | Huang W.,Key Laboratory of Coal Science and Technology
Journal of Molecular Modeling | Year: 2012

Methanol and dimethyl ether (DME) adsorption over clean and hydrated γ-Al2O3(100) and (110) surfaces was studied by using density functional theory (DFT) combined with conductor-like solvent model (COSMO) in gas phase and liquid paraffin. On clean γ-Al2O 3 (100) and (110) surfaces, DME and methanol preferentially interact with Al3 and Al1 of the γ-Al2O3(110) and (100) surfaces, respectively. On hydrated γ-Al2O3(100) and (110) surfaces, the OH group can influence the adsorptive behavior of DME and methanol. The Al3 and Al1 active sites of the hydrated (110) and (100) surfaces are inactivated due to hydroxyl influence, respectively. Compared to the adsorption energies of DME and methanol adsorption over the clean and hydrated (110) and (100) surfaces in gas phase and liquid paraffin, it is found that the solvent effects can slightly reduce adsorptive ability. © Springer-Verlag 2012.

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