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China’s energy—challenges and strategies
NI Weidou
Frontiers of Energy and Power Engineering in China. 2007, 1 (1): 1-8.
https://doi.org/10.1007/s11708-007-0001-2
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.
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The development of pollution control technology in coal combustion in China
XU Xuchang, ZHANG Hu, ZHUO Yuqun, TONG Huiling, WANG Shujuan, LI Yan
Frontiers of Energy and Power Engineering in China. 2007, 1 (1): 9-15.
https://doi.org/10.1007/s11708-007-0002-1
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.
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Integrated energy systems based on cascade utilization of energy
JIN Hongguang, GAO Lin, HAN Wei, LI Bingyu, FENG Zhibing
Frontiers of Energy and Power Engineering in China. 2007, 1 (1): 16-31.
https://doi.org/10.1007/s11708-007-0003-0
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.
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Cooling strategies and transport theories for brain hypothermia resuscitation
LIU Jing
Frontiers of Energy and Power Engineering in China. 2007, 1 (1): 32-57.
https://doi.org/10.1007/s11708-007-0004-z
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.
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Modeling of ion conductivity in Nafion membranes
YANG Zhen, PENG Xiaofeng, WANG Buxuan, DUAN Yuanyuan, LEE Duujong
Frontiers of Energy and Power Engineering in China. 2007, 1 (1): 58-66.
https://doi.org/10.1007/s11708-007-0005-y
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.
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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
Frontiers of Energy and Power Engineering in China. 2007, 1 (1): 79-84.
https://doi.org/10.1007/s11708-007-0007-9
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.
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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
Frontiers of Energy and Power Engineering in China. 2007, 1 (1): 113-119.
https://doi.org/10.1007/s11708-007-0013-y
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%.
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