The Experts below are selected from a list of 11940 Experts worldwide ranked by ideXlab platform
Long Zhang - One of the best experts on this subject based on the ideXlab platform.
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performance comparisons of desiccant wheels for air dehumidification and enthalpy recovery
Applied Thermal Engineering, 2002Co-Authors: Long Zhang, Jianlei NiuAbstract:Desiccant wheels have two major applications: air dehumidification and enthalpy recovery. Since the operating conditions are different, heat and mass transfer behaviors in the wheels are quite different. In this paper, the performances of desiccant wheels used in air dehumidification and enthalpy recovery are compared with each other. To accomplish this task, a two-dimensional, dual-diffusion transient heat and mass transfer model which takes into account the heat conduction, the surface and gaseous diffusion in both the axial and the thickness directions is presented. Effects of the Rotary Speed, the number of transfer units, and the specific area on the performance of the wheel are investigated and compared in the two situations. The cycles that the desiccant and air undergo in the wheel are plotted in psychrometric charts to demonstrate the different heat and moisture transfer mechanisms during the dehumidification and enthalpy recovery processes.
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performance comparisons of desiccant wheels for air dehumidification and enthalpy recovery
Applied Thermal Engineering, 2002Co-Authors: Long ZhangAbstract:Desiccant wheels have two major applications: air dehumidification and enthalpy recovery. Since the operating conditions are different, heat and mass transfer behaviors in the wheels are quite different. In this paper, the performances of desiccant wheels used in air dehumidification and enthalpy recovery are compared with each other. To accomplish this task, a two-dimensional, dual-diffusion transient heat and mass transfer model which takes into account the heat conduction, the surface and gaseous diffusion in both the axial and the thickness directions is presented. Effects of the Rotary Speed, the number of transfer units, and the specific area on the performance of the wheel are investigated and compared in the two situations. The cycles that the desiccant and air undergo in the wheel are plotted in psychrometric charts to demonstrate the different heat and moisture transfer mechanisms during the dehumidification and enthalpy recovery processes.
Jianlei Niu - One of the best experts on this subject based on the ideXlab platform.
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performance comparisons of desiccant wheels for air dehumidification and enthalpy recovery
Applied Thermal Engineering, 2002Co-Authors: Long Zhang, Jianlei NiuAbstract:Desiccant wheels have two major applications: air dehumidification and enthalpy recovery. Since the operating conditions are different, heat and mass transfer behaviors in the wheels are quite different. In this paper, the performances of desiccant wheels used in air dehumidification and enthalpy recovery are compared with each other. To accomplish this task, a two-dimensional, dual-diffusion transient heat and mass transfer model which takes into account the heat conduction, the surface and gaseous diffusion in both the axial and the thickness directions is presented. Effects of the Rotary Speed, the number of transfer units, and the specific area on the performance of the wheel are investigated and compared in the two situations. The cycles that the desiccant and air undergo in the wheel are plotted in psychrometric charts to demonstrate the different heat and moisture transfer mechanisms during the dehumidification and enthalpy recovery processes.
Fuhui Wang - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical study of drill string dynamics in gas drilling of horizontal wells
Journal of Natural Gas Science and Engineering, 2015Co-Authors: Zhanghua Lian, Qiang Zhang, Tiejun Lin, Fuhui WangAbstract:Abstract The combination of gas drilling and horizontal well has been considered as an effective technique for the exploitation of low permeability reservoirs to protect reservoir, enlarge drainage area and increase production. Given the currently inadequate understanding about drill string dynamic characteristics in gas drilling of horizontal wells, a theoretical model of drill string dynamics is established in this paper. The nonlinear dynamics equations are derived to study the motion state of drill string. Meanwhile, an experimental apparatus is developed according to similarity principle, and the kinetic characteristic of drill string is investigated based on the simulation experiment. Particular attention is focused on the lateral vibration which results from the impact and frictional interaction with wellbore constraint. The effect of weight on bit and Rotary Speed on drill string motion pattern is also discussed based on experimental results. Finally, the buckling and contact of drill string are analyzed through finite element simulation study. The results indicates that the contact force between wellbore and drill string is relatively large and helical buckling of drill string can be caused without the lubrication and damping effects of drilling fluid in gas drilling. The work presented in this paper can provide theoretical foundation and technological basis for drill string dynamics analysis and drilling parameter optimization in horizontal wells drilled with gas.
Xichen Zhang - One of the best experts on this subject based on the ideXlab platform.
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optimization of fermentation condition for antibiotic production by xenorhabdus nematophila with response surface methodology
Journal of Applied Microbiology, 2008Co-Authors: Y H Wang, Q. Zhang, Jing Feng, Xichen ZhangAbstract:Aims: To evaluate the influence of environmental parameters on the production of antibiotics (xenocoumacins and nematophin) by Xenorhabdus nematophila and enhance the antibiotic activity. Methods and Results: Response surface methodology (RSM) was employed to study the effects of five parameters (the initial pH, medium volume in flask, Rotary Speed, temperature and inoculation volume) on the production of antibiotics in flask cultures by X. nematophila YL001. A 25−1-factorial central composite design was chosen to explain the combined effects of the five parameters and to design a minimum number of experiments. The experimental results and software-predicted values of production of antibiotics were comparable. The statistical analysis of the results showed that, in the range studied, medium volume in flask, Rotary Speed, temperature and inoculation volume had a significant effect (P < 0·05) on the production of antibiotics at their individual level, medium volume in flask and Rotary Speed showed a significant influence at interactive level and were most significant at individual level. The maximum antibiotic activity was achieved at the initial pH 7·64, medium volume in 250 ml flask 25 ml, Rotary Speed of 220 rev min−1, temperature 27·8°C and inoculation volume of 15·0%. Maximum antibiotic activity of 331·7 U ml−1 was achieved under the optimized condition. Conclusions: As far as known, there are no reports of production of antibiotic from X. nematophila by engineering the condition of fermentation using RSM. The results strongly support the use of RSM for fermentation condition optimization. The optimization of the environmental parameters resulted not only in a 43·4% higher antibiotic activity than unoptimized conditions but also in a reduced amount of the experiments. The chosen method of optimization of fermentation condition was efficient, relatively simple and time and material saving. Significance and Impact of the Study: This study should contribute towards improving the antibiotics activity of X. nematophila. Integrated into a broader study of the impact of environmental factors on the production of antibiotic, this work should help to build more rational control strategy, possibly involving scale-up of production of antibiotics by X. nematophila.
Jinhe Liu - One of the best experts on this subject based on the ideXlab platform.
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pitting corrosion of friction stir welded aluminum alloy thick plate in alkaline chloride solution
Electrochimica Acta, 2010Co-Authors: Jinhe Liu, Hongqiang ZhuAbstract:The pitting corrosion of different positions (Top, Middle and Bottom) of weld nugget zone (WNZ) along thickness plate in friction stir welded 2219-O aluminum alloy in alkaline chloride solution was investigated by using open circuit potential, cyclic polarization, scanning electron microscopy and atomic force microscope. The results indicate that the material presents significant passivation, the top has highest corrosion potential, pitting potential and re-passivation potential compared with the bottom and base material. With the increase of traverse Speed from 60 to 100 mm/min or Rotary Speed from 500 to 600 rpm, the corrosion resistance decreases.
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microstructure and pitting corrosion of friction stir welded joints in 2219 o aluminum alloy thick plate
Corrosion Science, 2009Co-Authors: Jinhe LiuAbstract:Abstract Effect of welding parameters on the microstructure and pitting corrosion of different positions along the thickness of weld nugget zone in friction stir welded 2219-O aluminum alloy plate was investigated using scanning electron microscopy (SEM), polarization experiment and electrochemical impedance tests (EIS). It was found that the material presents significant passivation and the top has best corrosion resistance compared to the bottom and base material. Corrosion resistance decreases with the increase of traverse Speed from 60 to 100 mm/min at Rotary Speed 400 rpm. Corrosion resistance at Rotary Speed 600 rpm is lower than that at 500 rpm.
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temperature evolution microstructure and mechanical properties of friction stir welded thick 2219 o aluminum alloy joints
Materials & Design, 2009Co-Authors: Jinhe Liu, Guohong Luan, Chunlin DongAbstract:Abstract The aim of this work is to investigate the temperature evolution, microstructure and mechanical properties of the joint during friction stir welding of thick 2219-O aluminum alloy with the butt joint. Different types of thermocouple layouts were designed to measure the temperature evolutions during tool inserting and stable welding processes. Dynamic recrystallised structures in the weld nugget zone (WNZ) were observed and different grain sizes were presented through the thickness. Tensile testing results indicated that the tensile strength (σb) and yield strength (σ0.2) of joints increased and the elongation (δ) of joints decreased with increasing the tool Rotary Speed. The joint top had the highest mechanical properties. Most of the failures presented a ductile fracture in the joints. Vickers microhardness was measured across the joint top, middle and bottom, and through the thickness in the WNZ. The result showed that the microhardness of different zones varied significantly.
