Mar 2009, Volume 3 Issue 1
    

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  • Research articles
    Weidou NI , Shilie WENG ,
  • Research articles
    Linwei MA , Zheng LI , Feng FU , Weidou NI , Xiliang ZHANG ,
    The purposes, objectives and technology pathways for alternative energy development are discussed with the aim of reaching sustainable energy development in China. Special attention has been paid to alternative power and alternative vehicle fuels. Instead of limiting alternative energy to energy sources such as nuclear and renewable energy, the scope of discussion is extended to alternative technologies such as coal power with carbon capture and sequestration (CCS), electric and hydrogen vehicles. In order to take account of the fact that China’s sustainable energy development involves many dimensions, a six-dimensional indicator set has been established and applied with the aim of comprehensively evaluating different technology pathways in a uniform way. The analysis reaches the following conclusions: (a) in the power sector, wind power, nuclear power and hydro power should be developed as much as possible, while R&D of solar power and coal power with CCS should be strengthened continuously for future deployment. (b) in the transportation sector, there is no foreseeable silver bullet to replace oil on a large scale within the time frame of 20 to 30 years. To ease the severe energy security situation, expedient choices like coal derived fuels could be developed. However, its scale should be optimized in accordance to the trade-off of energy security benefits, production costs and environmental costs. Desirable alternative fuels (or technologies) like 2nd generation biofuels and electrical vehicles should be the subject of intensive R&D with the objective to be cost effective as early as possible.
  • REVIEW ARTICLE
    Ceji FU, Zhuomin M. ZHANG

    The ability to manufacture, control, and manipulate structures at extremely small scales is the hallmark of modern technologies, including microelectronics, MEMS/NEMS, and nano-biotechnology. Along with the advancement of microfabrication technology, more and more investigations have been performed in recent years to understand the influence of microstructures on radiative properties. The key to the enhancement of performance is through the modification of the reflection and transmission properties of electromagnetic waves and thermal emission spectra using one-, two-, or three-dimensional micro/nanostructures. This review focuses on recent developments in metamaterials–manmade materials with exotic optical properties, and other nanostructured materials, such as gratings and photonic crystals, for application in radiative energy transfer and energy conversion systems.

  • Research articles
    Jian XIAO , Jing LIU ,
    Mass and energy transport consists of one of the most significant physiological processes in nature, which guarantees many amazing biological phenomena and activities. Borrowing such idea, many state-of-the-art thermo-fluidic devices and materials such as artificial kidneys, carrier erythrocyte, blood substitutes and so on have been successfully invented. Besides, new emerging technologies are still being developed. This paper is dedicated to presenting a relatively complete review of the typical devices and materials in clinical use inspired by biological mass and energy transport mechanisms. Particularly, these artificial thermo-fluidic devices and materials will be categorized into organ transplantation, drug delivery, nutrient transport, micro operation, and power supply. Potential approaches for innovating conventional technologies were discussed, corresponding biological phenomena and physical mechanisms were interpreted, future promising mass-and-energy-transport-based bionic devices were suggested, and prospects along this direction were pointed out. It is expected that many artificial devices based on biological mass and energy transport principle will appear to better improve various fields related to human life in the near future.
  • REVIEW ARTICLE
    Qunzhi ZHU, Hyunjin LEE, Zhuomin M. HANG

    Radiative properties of rough surfaces, particulate media and porous materials are important in thermal engineerit transfer between surfaces and volume elements in participating media, as well as for accurate radiometric temperature measurements. In this paper, recent research on scattering of thermal radiation by rough surfaces, fibrous insulation, soot, aerogel, biological materials, and polytetrafluoroethylene (PTFE) was reviewed. Both theoretical modeling and experimental investigation are discussed. Rigorous solutions and approximation methods for surface scattering and volume scattering are described. The approach of using measured surface roughness statistics in Monte Carlo simulations to predict radiative properties of rough surfaces is emphasized. The effects of various parameters on the radiative properties of particulate media and porous materials are summarized.

  • Research articles
    Yonglin JU , Qingqing SHEN ,
    A brief review is presented on previous experimental results and correlations on the friction factor of cryocooler regenerators operating at oscillating flow and pulsating pressure conditions, for different mesh sizes of packed woven screens, focusing on the effects of different operating frequencies ranging from 20 to 80 Hz, at room and cryogenic temperatures. A comparison of the friction factor data with those of other studies is presented to clarify the reason for the difference. Finally, a new oscillating flow correlation of regenerators, in terms of several non-dimensional parameters, is discussed and compared.
  • Research articles
    Xiaoguang REN , Jiangdong ZHENG , Sefiane KHELLIl , Arumemi-Ikhide MICHAEL ,
    In order to enhance heat transfer and mitigate contamination in the boiling processes, a new type of vapor-liquid-solid (3-phase) circulating fluidized bed boiling system has been designed, combining a circulating fluidized bed with boiling heat transfer. Experimental results show an enhancement of the boiling curve. Flow visualization studies concerning flow hydrodynamics within the riser column are also conducted whose results are presented and discussed.
  • RESEARCH ARTICLE
    Wen XU, Laifeng LI, Rongjin HUANG, Min ZHOU, Liyun ZHENG, Linghui GONG, Chunmei SONG

    The energy conversion properties of Bi-Sb system thermoelectric materials doped by Ag was investigated. Bi85Sb15-xAgx (x=0, 1, 2, 3, 4) alloys with Ag substitution for Sb were synthesized by mechanical alloying and then pressed under 5 GPa at 523 K for 30 min. The phase structure of the alloys was characterized by X-ray diffraction. The electric conductivities and the seebeck coefficients were measured at the temperature range of 80-300 K. The results reveal that the electric conductivities of the Ag-doped Bi-Sb alloys are highly improved. The power factor of Bi85Sb14Ag1 reaches a maximum value of 2.98×10-3 W/(K2?m) at 255 K, which is about three times that of the un-doped sample Bi85Sb15 at the same temperature.

  • Research articles
    Weidou NI , Zhen CHEN , Zheng LI , Jian GAO ,
    The urgency and necessity of alternative fuels give an impetus to the development of modern coal chemical industry. Coal-based methanol/DME is the key element of this industry. Wind power, whose installed capacity increased at a rate of more than 100% in recent years, has the most developed technologies in renewable energy. However, there still exist many unsolved problems in wind power for on-grid utilization. A new integrated system which combines coal-based methanol/DME production with wind power is proposed in this paper. In this system, wind power is used to electrolyze water to produce H2 and O2. The O2 is fed to the gasifier as gasification agent. The H2 is mixed with the CO-rich gas to adjust the H2/CO to an appropriate ratio for methanol synthesis. In comparison with conventional coal-based methanol/DME system, the proposed system omits the expensive and energy-consuming ASU and greatly reduces the water gas shift process, which brings both advantages in the utilization of all raw materials and significant mitigation of CO2 emission. This system will be attractive in the regions of China which have abundant wind and coal resources.
  • Research articles
    Zhen HUANG , Xinqi QIAO , Wugao ZHANG , Junhua WU , Junjun ZHANG ,
    As a developing and the most populous country in the world, China faces major challenges in energy supply and environmental protection. It is of great importance to develop clean and alternative fuels for internal combustion engines. On the basis of researches on DME engine and vehicle at Shanghai Jiaotong University in the last twelve years, fuel injection, combustion, performance and exhaust emissions of DME engine and DME vehicle are introduced in this paper. The results indicate that DME engines can achieve high thermal efficiency and ultra low emissions, and will play a significant role in meeting the energy demand while minimizing environmental impact in China.
  • Research articles
    Chaokui QIN , Hongmei LU , Xiong LIU , Gerhard SCHMITZ ,
    A hybrid air-conditioning system that combines an engine-driven chiller with desiccant dehumidification was configured and experimentally tested to provide reliable data for energy consumption and operation cost. The engine performance and the desiccant wheel performance were measured and a numeric model previously set up for dehumidification capacity prediction was validated. For a reference building, the results based upon measured data show that under present electricity/gas price ratio, more than 40% of operation cost can be saved by the hybrid system.
  • Research articles
    Fuchen WANG , Xinwen ZHOU , Wenyuan GUO , Zhenghua DAI , Xin GONG , Haifeng LIU , Zunhong YU ,
    A non-catalytic POX of oven gas is proposed to solve the problem of secondary pollution due to solid wastes produced from the great amount of organic sulfur contained in oven gas in the traditional catalytic partial oxidation (POX) process. A study of the measurement of flow field and a thermodynamic analysis of the process characteristics were conducted. Results show that there exist a jet-flow region, a recirculation-flow region, a tube-flow region, and three corresponding reaction zones in the non-catalytic POX reformer. The combustion of oven gas occurs mainly in the jet-flow region, while the reformation of oven gas occurs mainly in the other two regions. Soot would not be formed by CH4 cracking at above 1200°C. Since there are very little C2+ hydrocarbons in oven gas, the soot produced would be very tiny, even if they underwent cracking reaction. The integrated model for entrained bed gasification process was applied to simulate a non-catalytic POX reformer. It indicated that the proper oxygen-to-oven gas ratio is 0.22–0.28 at different pressures in the oven gas reformation process.