The Experts below are selected from a list of 75 Experts worldwide ranked by ideXlab platform
Sheng Chen - One of the best experts on this subject based on the ideXlab platform.
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methane combustion in various regimes first and second thermodynamic law comparison between air firing and Oxyfuel Condition
Energy, 2016Co-Authors: Yongxin Feng, Kai Xu, Sheng Chen, Chuguang ZhengAbstract:MILD Oxyfuel combustion has been attracting increasing attention as a promising clean combustion technology. How to design a pathway to reach MILD Oxyfuel combustion regime and what can provide a theoretical guide to design such a pathway are two critical questions that need to be answered. So far there has been no open literature on these issues. A type of combustion regime classification map proposed in our previous work, based on the so-called ”Hot Diluted Diffusion Ignition” (HDDI) configuration, is adopted here as a simple but useful tool to solve these problems. Firstly, we analyze comprehensively the influences of various dilution atmosphere and fuel type on combustion regimes. The combustion regime classification maps are made out according to the analyses. In succession, we conduct a comparison between the map in air-firing Condition and its Oxyfuel counterpart. With the aid of the second thermodynamic-law analysis on the maps, it is easy to identify the major contributors to entropy generation in various combustion regimes in advance, which is crucial for combustion system optimization. Moreover, we find that, for the first time, a combustion regime classification map also may be used as a safety indicator. With the aid of these maps, some conclusions in previous publications can be explained more straightforwardly.
Chuguang Zheng - One of the best experts on this subject based on the ideXlab platform.
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methane combustion in various regimes first and second thermodynamic law comparison between air firing and Oxyfuel Condition
Energy, 2016Co-Authors: Yongxin Feng, Kai Xu, Sheng Chen, Chuguang ZhengAbstract:MILD Oxyfuel combustion has been attracting increasing attention as a promising clean combustion technology. How to design a pathway to reach MILD Oxyfuel combustion regime and what can provide a theoretical guide to design such a pathway are two critical questions that need to be answered. So far there has been no open literature on these issues. A type of combustion regime classification map proposed in our previous work, based on the so-called ”Hot Diluted Diffusion Ignition” (HDDI) configuration, is adopted here as a simple but useful tool to solve these problems. Firstly, we analyze comprehensively the influences of various dilution atmosphere and fuel type on combustion regimes. The combustion regime classification maps are made out according to the analyses. In succession, we conduct a comparison between the map in air-firing Condition and its Oxyfuel counterpart. With the aid of the second thermodynamic-law analysis on the maps, it is easy to identify the major contributors to entropy generation in various combustion regimes in advance, which is crucial for combustion system optimization. Moreover, we find that, for the first time, a combustion regime classification map also may be used as a safety indicator. With the aid of these maps, some conclusions in previous publications can be explained more straightforwardly.
Li Xiaoyu - One of the best experts on this subject based on the ideXlab platform.
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Long term stability and permeability of mixed ion conducting membranes under Oxyfuel Conditions
Publikationsserver der RWTH Aachen University, 2013Co-Authors: Li XiaoyuAbstract:The thermochemical properties, especially the long-term behaviour of mixed electron-ion conducting materials for oxygen separation, were investigated under Oxyfuel Condition in this thesis. Amongst those oxygen-permeable materials, perovskite-type oxides demonstrate remarkably high oxygen fluxes. Nevertheless, great effort has been put into the investigation of the long-term sustainable problem occurring in the intermediate temperature (IT) range of 500-800°C in some perovskite membranes, which is caused by thermodynamic decomposition. This decay of membrane properties during operation becomes a serious obstacle for applications in coal-fired power plants. Besides, a relatively low expansion coefficient of membrane materials is also suggested to avoid compatibility issues. Perovskite-structured BaxSr1-xCoyFe1-yO3-d (BSCF) materials were synthesized by the method of solid state reaction. The sintering behaviour of BSCF powders was studied prior to the production of the gastight membranes. In view of future application, characteristic membrane properties like melting temperature, oxygen nonstoichiometry and thermal expansion behaviour were measured in synthetic air accordingly. The association between the thermochemical properties and the doping compositions of BSCF materials as well as temperature effect was investigated. Moreover, the degradation process in BSCF membranes during long-term operation was studied under Oxyfuel Condition. In the case of oxygen permeation measurements, the variation of oxygen flux through the membranes under the air/He pressure gradient was recorded. A slow exponential decay of the permeate flux was observed at 800°C compared to the more stabilized oxygen permeability of membranes at higher temperatures. The reason for the deterioration of membrane permeability is mainly ascribed to the phase decomposition from cubic into hexagonal polymorph. Unexpectedly, an increment of oxygen flux was found in the Ba0.4Sr0.6Co0.2Fe0.8O3-d membrane measured at 850°C, though kinetic decomposition still occurs in this material. Based on the permeation behaviour of BSCF membranes during cyclic permeation tests, it is confirmed that the cubic-hexagonal phase transition is reversible and membrane performance could be retrieved by the periodical variation of temperatures above 850°C. The driving force as well as kinetics for the phase transition is discussed in this study according to the long-term annealing measurements. In conclusion, the oxygen permeability and stability of membranes are proven to be strongly dependent on temperature, oxygen partial pressure and chemical composition, most notably concerning the cobalt content
Yongxin Feng - One of the best experts on this subject based on the ideXlab platform.
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methane combustion in various regimes first and second thermodynamic law comparison between air firing and Oxyfuel Condition
Energy, 2016Co-Authors: Yongxin Feng, Kai Xu, Sheng Chen, Chuguang ZhengAbstract:MILD Oxyfuel combustion has been attracting increasing attention as a promising clean combustion technology. How to design a pathway to reach MILD Oxyfuel combustion regime and what can provide a theoretical guide to design such a pathway are two critical questions that need to be answered. So far there has been no open literature on these issues. A type of combustion regime classification map proposed in our previous work, based on the so-called ”Hot Diluted Diffusion Ignition” (HDDI) configuration, is adopted here as a simple but useful tool to solve these problems. Firstly, we analyze comprehensively the influences of various dilution atmosphere and fuel type on combustion regimes. The combustion regime classification maps are made out according to the analyses. In succession, we conduct a comparison between the map in air-firing Condition and its Oxyfuel counterpart. With the aid of the second thermodynamic-law analysis on the maps, it is easy to identify the major contributors to entropy generation in various combustion regimes in advance, which is crucial for combustion system optimization. Moreover, we find that, for the first time, a combustion regime classification map also may be used as a safety indicator. With the aid of these maps, some conclusions in previous publications can be explained more straightforwardly.
Kai Xu - One of the best experts on this subject based on the ideXlab platform.
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methane combustion in various regimes first and second thermodynamic law comparison between air firing and Oxyfuel Condition
Energy, 2016Co-Authors: Yongxin Feng, Kai Xu, Sheng Chen, Chuguang ZhengAbstract:MILD Oxyfuel combustion has been attracting increasing attention as a promising clean combustion technology. How to design a pathway to reach MILD Oxyfuel combustion regime and what can provide a theoretical guide to design such a pathway are two critical questions that need to be answered. So far there has been no open literature on these issues. A type of combustion regime classification map proposed in our previous work, based on the so-called ”Hot Diluted Diffusion Ignition” (HDDI) configuration, is adopted here as a simple but useful tool to solve these problems. Firstly, we analyze comprehensively the influences of various dilution atmosphere and fuel type on combustion regimes. The combustion regime classification maps are made out according to the analyses. In succession, we conduct a comparison between the map in air-firing Condition and its Oxyfuel counterpart. With the aid of the second thermodynamic-law analysis on the maps, it is easy to identify the major contributors to entropy generation in various combustion regimes in advance, which is crucial for combustion system optimization. Moreover, we find that, for the first time, a combustion regime classification map also may be used as a safety indicator. With the aid of these maps, some conclusions in previous publications can be explained more straightforwardly.
