Mar 2007, Volume 1 Issue 1
    

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  • China’s energy—challenges and strategies
    NI Weidou
    2007, 1(1): 1-8. https://doi.org/10.1007/s11708-007-0001-2
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    In this century, China started facing five major challenges in the energy field: energy supply, shortage of liquid fuel, environmental pollution, green house gas (GHG) emission, and energy supply in rural areas. In this paper, the Chinese energy development strategy and general technical scheme (including energy conservation, utilization of coal, alternative fuel and renewable energy) are discussed, and some key scientific problems in the fundamental research of energy are put forward.
  • The development of pollution control technology in coal combustion in China
    XU Xuchang, ZHANG Hu, ZHUO Yuqun, TONG Huiling, WANG Shujuan, LI Yan
    2007, 1(1): 9-15. https://doi.org/10.1007/s11708-007-0002-1
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    The recent development of coal combustion pollution control technologies in China, including desulphurization, denitrification, particulate matters and heavy metals emission control technologies, have been reviewed. The development histories and the advantages of China s self-developed technologies have been introduced in detail. The key points of future research and development in coal combustion pollution control, e.g., combined emission control and CO2 emission control technologies, have also been discussed.
  • Integrated energy systems based on cascade utilization of energy
    JIN Hongguang, GAO Lin, HAN Wei, LI Bingyu, FENG Zhibing
    2007, 1(1): 16-31. https://doi.org/10.1007/s11708-007-0003-0
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    Focusing on the traditional principle of physical energy utilization, new integration concepts for combined cooling, heating and power (CCHP) system were identified, and corresponding systems were investigated. Furthermore, the principle of cascade utilization of both chemical and physical energy in energy systems with the integration of chemical processes and thermal cycles was introduced, along with a general equation describing the interrelationship among energy levels of substance, Gibbs free energy of chemical reaction and physical energy. On the basis of this principle, a polygeneration system for power and liquid fuel (methanol) production has been presented and investigated. This system innovatively integrates a fresh gas preparation subsystem without composition adjustment process (NA) and a methanol synthesis subsystem with partial-recycle scheme (PR). Meanwhile, a multi-functional energy system (MES) that consumes coal and natural gas as fuels simultaneously, and co-generates methanol and power, has been presented. In the MES, coal and natural gas are utilized synthetically based on the method of dual-fuel reforming, which integrates methane/steam reforming and coal combustion. Compared with conventional energy systems that do not consider cascade utilization of chemical energy, both of these systems provide superior performance, whose energy saving ratio can be as high as 10% 15%. With special attention paid to chemical energy utilization, the integration features of these two systems have been revealed, and the important role that the principle of cascade utilization of both chemical and physical energy plays in system integration has been identified.
  • Cooling strategies and transport theories for brain hypothermia resuscitation
    LIU Jing
    2007, 1(1): 32-57. https://doi.org/10.1007/s11708-007-0004-z
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    The brain is one of the most important organs in a biological body whose normal function depends heavily on an uninterrupted delivery of oxygen. Unlike skeletal muscles that can survive for hours without oxygen, neuron cells in the brain are easily subjected to an irreversible damage within minutes from the onset of oxygen deficiency. With the interruption of cardiopulmonary circulation in many cardiac surgical procedures or accidental events leading to cerebral circulation arrest, an imbalance between energy production and consumption will occur which causes a rapid depletion of oxygen due to the interrupted blood-flow to the brain. Meanwhile, the cooling function of the blood flow on the hot tissue will be stopped, while metabolic heat generation in the tissues still keeps running for awhile. Under such adverse situations, the potential for cerebral protection through hypothermia has been intensively investigated in clinics by lowering brain temperature to restrain the cerebral oxygen demands. The reason can be attributed to the decreased metabolic requirements of the cold brain tissues, which allows a longer duration for the brain to endure reduced oxygen delivery. It is now clear that hypothermia would serve as the principal way for neurologic protection in a wide variety of emergency medicines, especially in cerebral damage, anoxia, circulatory arrest, respiratory occlusion, etc. However, although brain cooling has been found uniquely significant in clinical practices, the serious lack of knowledge on the mechanisms involved prevents its further advancement in brain resuscitation. Compared with the expanded trials in clinics, only very limited efforts were made to probe the engineering issues involved, which turns out to be a major obstacle for the successful operation of brain hypothermia resuscitation. From the viewpoint of biothermal medical engineering, the major theories and strategies for administering brain cooling can generally be classified into three categories: heat transfer, oxygen transport and cooling strategy. Aiming to provide a complete overview of the brain hypothermia resuscitation, this article comprehensively summarizes the recent progresses made in theoretical, practical and experimental techniques in the area. Particularly, attention is paid to the mathematical models to quantify the heat and oxygen transport inside the cerebral tissues. Typical cooling strategies to effectively lower brain temperature and thus decrease oxygen consumption rate in the cerebral tissues are analyzed. Approaches to deliver oxygen directly to the target tissues are discussed. Meanwhile, some future efforts worth pursuing within the area of brain cooling are suggested.
  • Modeling of ion conductivity in Nafion membranes
    YANG Zhen, PENG Xiaofeng, WANG Buxuan, DUAN Yuanyuan, LEE Duujong
    2007, 1(1): 58-66. https://doi.org/10.1007/s11708-007-0005-y
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    A theoretical investigation was conducted to describe the ion transport behavior in a Nafion Membrane of proton exchange membrane fuel cells (PEMFC). By analyzing the surface energy configuration of the ionic clusters in a Nafion membrane, an equivalent field intensity, Ee, was introduced to facilitate the analysis of surface resistance against ion conduction in the central region of clusters. An expression was derived for ionic conductivity incorporating the influence of surface resistance. A face-centered cubic (FCC) lattice model for a spatial cluster distribution was used to modify the effect of water content on ionic conductivity in the polymeric matrix, i.e., the regions between clusters. Compared with the available empirical correlations, the new expression showed much better agreement with the available experimental results, which indicates the rationality to consider the structural influence on ion conduction in water-swollen Nafion membranes.
  • Investigation on the integral output power model of a large-scale wind farm
    BAO Nengsheng, MA Xiuqian, NI Weidou
    2007, 1(1): 67-78. https://doi.org/10.1007/s11708-007-0006-x
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    The integral output power model of a large-scale wind farm is needed when estimating the wind farm s output over a period of time in the future. The actual wind speed power model and calculation method of a wind farm made up of many wind turbine units are discussed. After analyzing the incoming wind flow characteristics and their energy distributions, and after considering the multi-effects among the wind turbine units and certain assumptions, the incoming wind flow model of multi-units is built. The calculation algorithms and steps of the integral output power model of a large-scale wind farm are provided. Finally, an actual power output of the wind farm is calculated and analyzed by using the practical measurement wind speed data. The characteristics of a large-scale wind farm are also discussed.
  • Identifying combustion intermediates in premixed MTBE/gasoline/oxygen flame probed via synchrotron radiation
    YAO Chunde, LI Jing, LI Qi, JI Qing, HUANG Chaoqun, WEI Lixia, WANG Jing, TIAN Zhenyu, LI Yuyang, QI Fei
    2007, 1(1): 79-84. https://doi.org/10.1007/s11708-007-0007-9
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    Molecular-beam sampling mass spectrometry (MBMS) combined with tunable synchrotron radiation photoionization technique offers obvious advantages for the study of flame chemistry over other techniques because of the precision measurement of the combustion intermediates and products in flame. In this paper, the results to identify combustion intermediates in low-pressure premixed gasoline/oxygen flame with the synchrotron radiation were reported. Based on the results obtained, the formation process of five products and the difference between gasoline/oxygen and MTBE/gasoline/oxygen flame were emphatically analyzed. The results achieved provide data basis for the analysis of intermediates and radicals in flame, and are helpful to establish the kinetic modeling of gasoline/oxygen and MTBE/gasoline/oxygen flames.
  • Investigation on regeneration and energy storage characteristics of a solar liquid desiccant air-conditioning system
    SHI Mingheng, DU Bin, ZHAO Yun
    2007, 1(1): 85-90. https://doi.org/10.1007/s11708-007-0008-8
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    Solar liquid desiccant air-conditioner is a new air-conditioning system in which liquid desiccant can be regenerated by solar energy and energy can be stored in the form of chemical energy in the liquid desiccant. In this paper regeneration and energy storage characteristics were studied theoretically and experimentally. Two criterion equations for heat and mass transfer in the regeneration process were obtained. The main factors that influence the regeneration process were analyzed. A principal solar liquid desiccant air-conditioning system under energy storage operating mode is proposed.
  • Study on the NOx release rule along the boiler during pulverized coal combustion
    JIN Jing, ZHANG Zhongxiao, LI Ruiyang
    2007, 1(1): 91-95. https://doi.org/10.1007/s11708-007-0009-7
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    Numerical simulation and experimental study on NOx release along the boiler during pulverized coal combustion have been conducted. With the increase of temperature the NOx emission increased and the peak value of NOx release moved forward. But when the temperature increased to a certain degree, NOx emission began to reduce. NOx emission increased with the increase of nitrogen content of coal. The peak value of NOx release moved backwards with the increase of coal rank. NOx emission increased obviously with the increase of stoichiometric ratio. There existed a critical average diameter of the pulverized coal (dc). If d"ddc, NOx emission reduced with the decrease of pulverized coal size. If d>dc, NOx emission reduced with the increase of the pulverized coal size. The results showed that the simulation results are in agreement with the experimental results for concentration distribution of NOx along the axis of the furnace.
  • Study on combustion characteristics of blended coals
    LI Yonghua, WANG Chunbo, CHEN Hongwei
    2007, 1(1): 96-100. https://doi.org/10.1007/s11708-007-0010-1
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    Power plants in China have to burn blended coal instead of one specific coal for a variety of reasons. So it is of great necessity to investigate the combustion of blended coals. Using a test rig with a capacity of 640 MJ/h with an absolute milling system and flue gas online analysis system, characteristics such as burnout, slag, and pollution of some blended coals were investigated. The ratio of coke and slag as a method of distinguishing coal slagging characteristic was introduced. The results show that the blending of coal has some effect on NOx but there is no obvious rule. SOx emission can be reduced by blending low sulfur coal.
  • A density functional theory study of the adsorption of Hg and HgCl2 on a CaO(001) surface
    GUO Xin, ZHENG Chuguang, LU Nanxia
    2007, 1(1): 101-104. https://doi.org/10.1007/s11708-007-0011-0
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    The adsorption of mercury and mercury chloride on a CaO(001) surface was investigated by the density functional theory (DFT) by using Ca9O9 cluster embedded in an electrostatic field represented by 178 point charges at the crystal CaO lattice positions. For the mercury molecular axis normal to the surface, the mercury can only coordinate to the O2- anion and has a very weak binding energy of 19.649 kJ/mol. When the mercury chloride molecular axis is vertical to the surface, the Cl atom coordinates to the Ca2+ cation and has a binding energy of 23.699 kJ/mol. When the mercury chloride molecular axis is parallel to the surface, the Hg atom coordinates to the O2- anion and has a binding energy of 87.829 kJ/mol, which means that the parallel geometry is more stable than the vertical one. The present calculations show that CaO injection could substantially reduce gaseous mercury chloride, but have no apparent effect on the mercury, which is compatible with the available experimental results. This research will provide valuable information for optimizing and selecting a sorbent for the trace element in flue gas.
  • Spray characteristics of high-pressure swirl injector fueled with alcohol
    WANG Xibin, CHEN Wansheng, GAO Jian, JIANG Deming, HUANG Zuohua
    2007, 1(1): 105-112. https://doi.org/10.1007/s11708-007-0012-z
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    The spray characteristics of methanol and ethanol with high-pressure swirl injector were explored experimentally and numerically. Experimental results show that the spray characteristics of methanol and ethanol had displayed the same trends as that of gasoline. Under the low back-pressure ambient conditions, the spray behavior exhibited a hollow cone with wide spray angle and initial spray slug at the tip, while the spray presented a solid cone in the case of high back-pressure. Vortexes in the opposite direction existed in the rear part of the spray under low back-pressure ambient conditions while the vortexes formed in the middle part under high back-pressure ambient conditions. Experiments also showed that methanol had the largest cone angle, while ethanol and gasoline presented almost the same cone angle. Simulation results indicated that methanol and ethanol had a slightly larger Sauter mean diameter (SMD) than that of gasoline with swirl injector. The SMD profile of methanol coincided well with that of ethanol under low back-pressure ambient conditions, but displayed a slightly larger value under high back-pressure due to fuel evaporation. Numerical simulation could successfully demonstrate the spray characteristics of high-pressure swirl injector for methanol and ethanol fuels.
  • Optimization and performance prediction of a new near-zero emission coal utilization system with combined gasification and combustion
    GUAN Jian, WANG Qinhui, LI Xiaomin, LUO Zhongyang, CEN Kefa
    2007, 1(1): 113-119. https://doi.org/10.1007/s11708-007-0013-y
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    In accordance with the new near-zero emission coal utilization system with combined gasification and combustion, which is based on the CO2 acceptor gasification process, the product gas composition of the gasifier and the combustor was calculated by means of thermodynamic equilibrium calculation software FactSage 5.2. Based on these calculations, the whole system efficiency calculation method that complies with the mass and energy conservation principle was established. To enhance the system efficiency, the system pressure and the gasifier carbon conversion ratio were optimized. The results indicate that the system efficiency increases with increasing pressure and gasifier carbon conversion ratio. After taking into consideration the influence of the pressure and carbon conversion ratio on the performance of the system, the gasifier and the combustor were synthetically studied. The optimum system pressure and carbon conversion ratio were obtained as 2.5 MPa and 0.7, respectively. The system efficiency could reach around 62.1% when operated in these two optimum parameters. If the advanced ion transport membrane (ITM) air separation technology is used, there would be an increase of another 1.3%.
  • Intracellular trehalose improves the survival of human red blood cells by freeze-drying
    HE Hui, LIU Baolin, HUA Zezhao, LI Chuan, WU Zhengzheng
    2007, 1(1): 120-124. https://doi.org/10.1007/s11708-007-0014-x
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    Freeze-drying of human red blood cells has a potential important application for blood transfusion. The aim of this study was to investigate the effects of intracellular trehalose on the survival of red blood cells after freeze-drying and rehydration. Fresh red blood cells were incubated in trehalose solutions of various concentrations at 37vH for 7 h following freeze-drying. Polyvinylpyrrolidone, Trehalose, sodium citrate, and human serum albumin were used as extracellular protective agents for the freeze-drying of red blood cells. The results indicated that the intracellular trehalose concentration was increased with increasing concentration of extracellular trehalose solution, and the maximum concentration of intracellular trehalose reached 35 mmol/L. The viability of freeze-dried red blood cells increased with the increment of intracellular trehalose concentration.