Sep 2009, Volume 3 Issue 3
    

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  • Research articles
    Multi-objective dynamic optimization model for China’s road transport energy technology switching
    Dan GAO , Zheng LI , Feng FU , Linwei MA
    2009, 3(3): 247-253. https://doi.org/10.1007/s11708-009-0048-3
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    Deducting the future switching of the road transport energy technology is one of the key preconditions for relative technology development planning. However, one of the difficulties is to address the issue of multi-objective and conflicting constrains, e.g., minimizing the climate mitigation or minimizing economic cost. In this paper, a dynamic optimization model was established, which can be used to analyze the road transport energy technology switching under multi-objective constrains. Through one case study, a series of solutions could be derived to provide decision-makers with the flexibility to choose the appropriate solution with respect to the given situation.
  • Research articles
    Numerical study and control method of interaction of nucleation and boundary layer separation in condensing flow
    Liansuo AN , Zhi WANG , Zhonghe HAN ,
    2009, 3(3): 254-261. https://doi.org/10.1007/s11708-009-0047-4
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    The spontaneous nucleation flow in turbine cascade was numerically studied. The model was implemented within a full Navier–Stokes viscous flow solution procedure and the process of condensation was calculated by the quadrature method of moments that shows good accuracy with very broad size distributions. Results were presented for viscous and inviscous flow, showing the influence of boundary layer separation and wake vortices on spontaneous nucleation. The results show that the degree of flow separation in wet steam flow is greater than that in superheated steam flow due to condensation shock and that the loss cannot be neglected. Furthermore, the impact of boundary layer separation and wake vortices on velocity profiles and its implications for profile loss were considered. The calculations showed that layer separation and wake vortices influence nucleation rate, leading to different droplet distributions. A method for controlling homogeneous nucleation and for reducing degree of flow separation in high-speed transonic wet steam flow was presented. The liquid phase parameter distribution is sensitive to the suction side profile of turbine cascade, which impacts the nucleation rate distribution leading to different droplet distributions and affects the degree of flow separation. The numerical study provides a practical design method for turbine blade to reduce wetness losses.
  • Research articles
    Emerging technologies to power next generation mobile electronic devices using solar energy
    Dewei JIA , Yubo DUAN , Jing LIU ,
    2009, 3(3): 262-288. https://doi.org/10.1007/s11708-009-0015-z
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    Mobile electronic devices such as MP3, mobile phones, and wearable or implanted medical devices have already or will soon become a necessity in peoples’ lives. However, the further development of these devices is restricted not only by the inconvenient charging process of the power module, but also by the soaring prices of fossil fuel and its downstream chain of electricity manipulation. In view of the huge amount of solar energy fueling the world biochemically and thermally, a carry-on electricity harvester embedded in portable devices is emerging as a most noteworthy research area and engineering practice for a cost efficient solution. Such a parasitic problem is intrinsic in the next generation portable devices. This paper is dedicated to presenting an overview of the photovoltaic strategy in the chain as a reference for researchers and practitioners committed to solving the problem.
  • Research articles
    Convective mass transfer from a horizontal rotating cylinder in a slot air jet flow
    Hongting MA , Dandan MA , Na YANG ,
    2009, 3(3): 289-296. https://doi.org/10.1007/s11708-009-0019-8
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    The effects of air jet impinging on the mass transfer characteristics from a rotating spinning cylinder surface were experimentally investigated. The effects of rotational Reynolds number"Graphic", jet-exit Reynolds number "Graphic", the nozzle width-to-cylinder diameter ratio "Graphic", and the ratio of the distance between nozzle exit and the front of cylinder to nozzle width "Graphic" on the mean "Graphic" were determined. The phenomena of the first and second critical point was analyzed and validated. On the basis of experimental data, the correlation equation was obtained.
  • Research articles
    Investigation of vortical flows over oscillating body using fast Lagrangian vortex method
    Baoshan ZHU ,
    2009, 3(3): 297-306. https://doi.org/10.1007/s11708-009-0010-4
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    A computational method facilitating long-time and high-resolution unsteady vortical flows is developed with the advantages of the discrete vortex methods. Both the velocity and pressure distribution of the flow field are calculated by integral formulations in combination with a fast summation algorithm. The vorticity field is described by Lagrangian representation, which is well suited to the moving boundary. Viscosity diffusion of the vorticity is considered with the core spreading model corrected by an adaptive splitting and merging algorithm. The effectiveness of the present method is examined by comparing the numerical results of unsteady separated flows which pass a cylinder and a thin cambered blade undergoing rotational oscillations with available experimental results. Interesting results about vortex shedding patterns and lock-in characteristics are provided for the thin cambered blade.
  • Research articles
    Synchronous observation of rising soluble bubble through quiescent solution
    Yifu ZHANG , Shuai TIAN , Weizhong LI , Yongchen SONG ,
    2009, 3(3): 307-312. https://doi.org/10.1007/s11708-009-0028-7
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    An experimental method using computer image processing technology (CIPT) was proposed to observe and investigate the velocity, deformation, heat and mass transfer, etc. of a rising soluble gas (CO2) bubble through a quiescent hot water. A model was set up to describe the behavior of the bubble in a visual experimental system in which a high-speed camera rose instantaneously with the movement of the bubble. A series of trajectory videos about the bubble were recorded by a computer linked to the camera. The trajectory, volume changes and rate of mass transfer of the bubble were obtained by the CIPT. It is found that the single bubble follows a rolling trajectory at the initial stage when there is mass transfer. With the volume decreasing, the disturbed behavior of the bubble becomes tempered. When the rising velocity of the bubble reaches the maximum, the velocity is nearly at a constant. The experimental and analysis results show that this method is useful for the research on the mass transfer and the movement of rising bubbles in liquid.
  • Research articles
    Cooling performance of grid-sheets for highly loaded ultra-supercritical steam turbines
    Dieter BOHN , Robert KREWINKEL , Shuqing TIAN ,
    2009, 3(3): 313-320. https://doi.org/10.1007/s11708-009-0036-7
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    In order to increase efficiency and achieve a further CO2-reduction, the next generation of power plant turbines will have steam turbine inlet temperatures that are considerably higher than the current ones. The high pressure steam turbine inlet temperature is expected to be increased up to approximately 700°C with a live steam pressure of 30MPa. The elevated steam parameters in the high and intermediate pressure turbines can be encountered with Ni-base alloys, but this is a costly alternative associated with many manufacturing difficulties. Collaborative research centre 561 “Thermally Highly Loaded, Porous and Cooled Multi-Layer Systems for Combined Cycle Power Plants” at RWTH Aachen University proposes cooling the highly loaded turbines instead, as this would necessitate the application of far less Ni-base alloys.
    To protect the thermally highly loaded components, a sandwich material consisting of two thin face sheets and a core made from a woven wire mesh is used to cover the walls of the steam turbine casing. The cooling steam is led through the woven wire mesh between the two face sheets to achieve a cooling effect. The wire mesh provides the grid-sheet with structural rigidity under varying operating conditions.
    In the present work, the cooling performance of the grid-sheets will be investigated applying the conjugate heat transfer method to ultra-supercritical live and cooling steam conditions for a section of the cooling structure. The behaviour of the flow and the heat transfer in the grid-sheet will be analyzed in detail using a parameter variation. The numerical results should give a first prediction of the cooling performance under future operating conditions.
  • Research articles
    Exhaust hood for steam turbines-single-flow arrangement
    Michal HOZNEDL , Ladislav TAJC , Jaroslav KREJCIK , Lukas BEDNAR , Kamil SEDLAK , Jiri LINHART ,
    2009, 3(3): 321-329. https://doi.org/10.1007/s11708-009-0039-4
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    In the past, increased attention was given to the development of an optimal shape for the inlet part of LP turbine casings in SKODA POWER. A double-flow design is typically used for high power output turbines. An optimized shape for the internal diffuser has been found, which transforms the kinetic energy of steam into increased pressure, thus effectively increasing the thermodynamic efficiency of the stage. Some conclusions have been drawn from laboratory experiments, others derived directly from on-site measurements at power plants. The conclusions from the development of double-flow turbines form the basis for the design of the single-flow turbine arrangement. Single-flow design is typically used for lower output turbines. There are still some limitations in applying this arrangement. The designer needs to resolve the bearing position and how to ensure access to them. Reinforcing the ribs and supports are used, therefore, to ensure the rigidity of the entire casing. The optimization of the single-flow diffuser shape is therefore the subject of the study presented below.
  • Research articles
    Status of domestic gasification technology in China
    Zhimin HUANG , Jiansheng ZHANG , Guangxi YUE ,
    2009, 3(3): 330-336. https://doi.org/10.1007/s11708-009-0021-1
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    Five domestic gasification technologies in China were presented and reviewed, including opposed multi-burner (OMB) gasification technology of coal water slurry (CWS), oxygen staged gasification technology, two-stage dry feed entrained flow gasification, pulverized coal gasification process of HT-L, and ash agglomerating fluidized bed gasification. The former four technologies belong to pressurized entrained flow gasification technology. The process description, technology characteristics, research and development process, performance indexes and commercialization progress of these technologies were mainly discussed.
  • Research articles
    A reliability growth model for 300?MW pumped-storage power units
    Jinyuan SHI , Yu YANG , Zhicheng DENG ,
    2009, 3(3): 337-340. https://doi.org/10.1007/s11708-009-0032-y
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    A reliability growth model for pumped-storage power units is presented. Ways for estimating and fitting on checking the model’s parameters are given together with analysis results concerning the reliability growth of 300MW pumped-storage power units. On site operation, reliability data show that the reliability growth model conforms to rules of reliability growth tendency. Analysis results of reliability growth indicate that measures taken for improving maintenance and operation by the pumped-storage power companies are effective and that the reliability of the 300MW pumped-storage power units exhibits a rising tendency.
  • Research articles
    Design and analysis of dual fuel methanol-power poly-generation
    Minghua WANG , Zheng LI , Weidou NI ,
    2009, 3(3): 341-347. https://doi.org/10.1007/s11708-009-0023-z
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    A dual fuel head poly-generation flowsheet was designed based on coal gas and coke oven gas. To help clearly understand the system performance, a 1.2×108−3.2×108kg methanol and 274―496MW power poly-generation system was simulated by using the commercially available software ASPEN Plus and GT Pro. The technology scheme, the operating parameters, and the efficiency of the system were also analyzed and evaluated, which will be used for building industrial devices.
  • Research articles
    Development of MCBurn and its application in the analysis of SCWR physical characteristics
    Ganglin YU , Kan WANG ,
    2009, 3(3): 348-352. https://doi.org/10.1007/s11708-009-0031-z
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    The MCBurn, a coupled code system linking the Monte Carlo N-particle transport code(MCNP) and Oak Ridge isotope generation and depletion code (ORIGEN), can resolve the basic calculation problems in reactor physical design and analysis, such as criticality, power distribution, nuclide burn up, and neutron fluence. It has been verified in the pressurized water reactor (PWR) pin model, fast reactor (FR) burn up model, and boiling water reactor(BWR) assemble model with benchmarked results. In supercritical water reactor (SCWR) physical calculations, the calculation conditions such as the geometry, the neutron spectrum, and the fuel materials, etc., are more complex than those in traditional reactors, which is a great challenge to reactor physics calculation code. However, the MCBurn code is a possible solution. In this paper, several update functions of the MCBurn in new neutron cross-section lib, code interface, and neutron flux distribution were described. The application of the MCBurn in SCWR were verified on a supercritical water reactor assemble. The calculation results show that the MCBurn is accurate and adaptable in the SCWR calculation.
  • Research articles
    Numerical simulation of charge stratifications to improve combustion and NO formation of lean-burn SI engines
    Zhijun PENG ,
    2009, 3(3): 353-358. https://doi.org/10.1007/s11708-009-0035-8
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    The influences of charge stratification on spark ignition (SI) engine combustion and NO emission were analyzed using a phenomenological model. The mixture in the cylinder was divided spherically into three parts: a central core with a stoichiometric air-fuel charge, a dilution region without any combustible charge, and a mixing region lying between the core and the dilution region. Three mixture stratification parameters such as the extent of dilution in the mixing region, the extent of combustible charge in the mixing region, and the gradient of stratification in the mixing region were investigated. The results indicate that the extent of combustible charge in the mixing region could reduce in-cylinder NO formation significantly, compared with the extent of dilution in the mixing region. As long as the degree of dilution in the mixing region is within the dilution limit of the combustible charge, the gradient of dilution has little effect on combustion and NO formation.
  • Research articles
    Syngas composition study
    Zhe WANG , Jinning YANG , Zheng LI , Yong XIANG ,
    2009, 3(3): 369-372. https://doi.org/10.1007/s11708-009-0044-7
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    The syngas composition characteristic was investigated in the real slurry-feed gasifier using a detailed gas phase reaction mechanism. The results show that the time for syngas to reach equilibrium is much shorter than the residence time for slurry feed entrained-flow gasifiers, indicating a gas phase species partial equilibrium state. Further calculation shows that the four major species, CO, CO2, H2, and H2O, are in equilibrium via the reaction "Graphic". Suggestions are provided for future modeling and model validation.