The purpose of this paper is to investigate the feasibility of high-frequency induction heat for the line heating process through a series of experimental studies and numerical calculations. The results show that the ...The purpose of this paper is to investigate the feasibility of high-frequency induction heat for the line heating process through a series of experimental studies and numerical calculations. The results show that the heating temperature of induction heating meets the demands of steel plate bending, and the deformation of a steel plate heated by induction heating can achieve the same effect as flame heating. Meanwhile, the finite element model of moving induction heating of the plate is developed, and the comparison of the residual strain fields and transverse shrinkage between these two kinds of heating shows that great similarity has been achieved.展开更多
Post-combustion amine absorption and stripping can remove 90% of the CO2 from power plant flue gas, but systems can reduce electrical output by approximately 30% due to energy requirements for stripping CO2 from solve...Post-combustion amine absorption and stripping can remove 90% of the CO2 from power plant flue gas, but systems can reduce electrical output by approximately 30% due to energy requirements for stripping CO2 from solvent and CO2 compression. The CO2 capture energy penalty can be reduced while developing renewable energy technologies by meeting CO2 capture energy requirements with a solar thermal energy system, particularly when electricity demand and prices are the highest. This study presents an initial review of solar thermal technologies for supplying CO2 capture energy, with a focus on high temperature systems. Parabolic troughs and central receivers are technically able to provide energy for CO2 capture. However, the solar system＇s capital costs would be roughly half that of the base coal-fired plant with CO2 capture, and high electricity prices are required to offset the costs of operating the solar thermal system. For high temperature solar thermal systems, direct electricity generation is likely a more efficient way to use solar energy to replace output lost to CO2 capture energy. However, low temperature solar thermal systems might integrate better with solvent stripping equipment, and more rigorous analysis is required to definitively assess the feasibility of using solar energy for CO2 capture.展开更多
The heat transfer analysis of variable conductance heat pipe air preheater was carried out. The temperature trans-fer matrix was obtained for the air preheater that comprises several discrete heat transfer units with ...The heat transfer analysis of variable conductance heat pipe air preheater was carried out. The temperature trans-fer matrix was obtained for the air preheater that comprises several discrete heat transfer units with same or different heat transfer surface area in a parallel or counter flow mode. By using the temperature transfer matrix, the outlet fluid temperatures could be easily calculated for a given air preheater and inlet fluid temperatures. The active length of condenser in a variable conductance heat pipe is determined according to the flat interface model. With the same initial conditions, the comparisons between variable conductance heat-pipe air preheater and regular heat pipe air preheater has been analyzed and tested in terms of heat pipe wall temperature, heat transfer surface area and outlet fluid temperatures. Based on the real industrial applications, it has been confirmed that the variable conductance heat pipe air preheater has excellent performance of anti-corrosion and anti-ash-deposition especially at the variable working condition and the sulfur coal (5%-6% mass fraction of sulfur) condition.展开更多
Aims The importance of density-dependent mortality in maintaining tree species diversity is widely accepted.However,density-dependent effects may vary in magnitude and direction with different abiotic conditions in fo...Aims The importance of density-dependent mortality in maintaining tree species diversity is widely accepted.However,density-dependent effects may vary in magnitude and direction with different abiotic conditions in forests.Theoretical predictions surmise that density-dependent effects may vary with soil available nitrogen(AN),but this still needs to be tested.Methods We analyzed the density-dependent effects on survival of newly germinated seedlings for 18 common species based on a long-term seedling census across environmental gradients in a subtropical forest.We also conducted a root lesion detection experiment for five species to investigate the potential effects of pathogens on variation in density-dependent disease between rich and poor AN environments.Important Findings The seedling dynamics analysis revealed that the strength of density-dependent effects increased with AN,shifting from neutral or positive with low AN to negative with high AN.Three of the five tree species had stronger density-dependent effects on root lesions in rich AN environments than in poor AN environments,which is consistent with the results of a long-term seedling dynamics analysis.We also found higher species diversity in rich AN environments,which may be promoted by the stronger negative density-dependent effects.Both the seedling dynamic analysis and root lesion detection experiment revealed stronger negative density-dependent effects in higher AN environment,resulting from stronger disease pressure by soil pathogens.Our study emphasized the importance of considering context dependence when testing the density dependence hypotheses.展开更多
基金Supported by the National Natural Science Foundation of China (50805016)
文摘The purpose of this paper is to investigate the feasibility of high-frequency induction heat for the line heating process through a series of experimental studies and numerical calculations. The results show that the heating temperature of induction heating meets the demands of steel plate bending, and the deformation of a steel plate heated by induction heating can achieve the same effect as flame heating. Meanwhile, the finite element model of moving induction heating of the plate is developed, and the comparison of the residual strain fields and transverse shrinkage between these two kinds of heating shows that great similarity has been achieved.
文摘Post-combustion amine absorption and stripping can remove 90% of the CO2 from power plant flue gas, but systems can reduce electrical output by approximately 30% due to energy requirements for stripping CO2 from solvent and CO2 compression. The CO2 capture energy penalty can be reduced while developing renewable energy technologies by meeting CO2 capture energy requirements with a solar thermal energy system, particularly when electricity demand and prices are the highest. This study presents an initial review of solar thermal technologies for supplying CO2 capture energy, with a focus on high temperature systems. Parabolic troughs and central receivers are technically able to provide energy for CO2 capture. However, the solar system＇s capital costs would be roughly half that of the base coal-fired plant with CO2 capture, and high electricity prices are required to offset the costs of operating the solar thermal system. For high temperature solar thermal systems, direct electricity generation is likely a more efficient way to use solar energy to replace output lost to CO2 capture energy. However, low temperature solar thermal systems might integrate better with solvent stripping equipment, and more rigorous analysis is required to definitively assess the feasibility of using solar energy for CO2 capture.
文摘The heat transfer analysis of variable conductance heat pipe air preheater was carried out. The temperature trans-fer matrix was obtained for the air preheater that comprises several discrete heat transfer units with same or different heat transfer surface area in a parallel or counter flow mode. By using the temperature transfer matrix, the outlet fluid temperatures could be easily calculated for a given air preheater and inlet fluid temperatures. The active length of condenser in a variable conductance heat pipe is determined according to the flat interface model. With the same initial conditions, the comparisons between variable conductance heat-pipe air preheater and regular heat pipe air preheater has been analyzed and tested in terms of heat pipe wall temperature, heat transfer surface area and outlet fluid temperatures. Based on the real industrial applications, it has been confirmed that the variable conductance heat pipe air preheater has excellent performance of anti-corrosion and anti-ash-deposition especially at the variable working condition and the sulfur coal (5%-6% mass fraction of sulfur) condition.
基金funded by the National Natural Science Foundation of China(31830010,31870403,31770466 and 31500334)the National Key Research and Development Program of China(Project No.2017YFA0605100)the Zhang-Hongda Science Foundation of SYSU.
文摘Aims The importance of density-dependent mortality in maintaining tree species diversity is widely accepted.However,density-dependent effects may vary in magnitude and direction with different abiotic conditions in forests.Theoretical predictions surmise that density-dependent effects may vary with soil available nitrogen(AN),but this still needs to be tested.Methods We analyzed the density-dependent effects on survival of newly germinated seedlings for 18 common species based on a long-term seedling census across environmental gradients in a subtropical forest.We also conducted a root lesion detection experiment for five species to investigate the potential effects of pathogens on variation in density-dependent disease between rich and poor AN environments.Important Findings The seedling dynamics analysis revealed that the strength of density-dependent effects increased with AN,shifting from neutral or positive with low AN to negative with high AN.Three of the five tree species had stronger density-dependent effects on root lesions in rich AN environments than in poor AN environments,which is consistent with the results of a long-term seedling dynamics analysis.We also found higher species diversity in rich AN environments,which may be promoted by the stronger negative density-dependent effects.Both the seedling dynamic analysis and root lesion detection experiment revealed stronger negative density-dependent effects in higher AN environment,resulting from stronger disease pressure by soil pathogens.Our study emphasized the importance of considering context dependence when testing the density dependence hypotheses.
