Solid oxide fuel cell(SOFC) vehicles are considered to have broad prospects for development, and the high operating temperature of SOFC results in great potential for waste-heat recovery. Many concepts for utilizing w...Solid oxide fuel cell(SOFC) vehicles are considered to have broad prospects for development, and the high operating temperature of SOFC results in great potential for waste-heat recovery. Many concepts for utilizing waste heat of SOFC have been suggested and studied, and most of them directly couple an SOFC to a gas turbine, which require the SOFC to operate at an elevated pressure and make the system less flexible and thus harder to operate. In recent years, with the development of turbine and heat exchanger technology, the supercritical carbon dioxide(S-CO_2) power cycle has raised widespread attractions for the waste recovery. This study explores the potential of S-CO_2 Brayton cycle to realize waste-heat recovery for an SOFC vehicle. The SOFC can operate at atmospheric pressure, and the hybrid system is easier to operate than the directly coupled systems. In this paper, a simple recuperated S-CO_2 Brayton cycle is proposed and the key component, radial inflow turbine is designed and focused. The flow state of the designed turbine is analyzed in detail based on computational fluid dynamics(CFD) numerical simulation. Five cases with different impeller tip clearances are numerically simulated to study its influence on the turbine performance. In addition, off-design performance analysis of the radial inflow turbine is conducted considering the temperature fluctuation of SOFC in practical applications.展开更多
It is usually to conduct a full-scale three-dimensional flow analysis for a radial turbine to find a way to increase the efficiency of a Compressed Air Energy Storage(CAES)system.However,long solving time and huge con...It is usually to conduct a full-scale three-dimensional flow analysis for a radial turbine to find a way to increase the efficiency of a Compressed Air Energy Storage(CAES)system.However,long solving time and huge consumption of computing resources become a major obstacle to the analysis.Therefore,in present study,a surrogate model with test data-based multi-layer perceptron(MLP)Neural Network is proposed to overcome the difficulty.Instead of complex flow field solving process,it provides reliable turbine aerodynamic performance and flow field distribution characteristics in a short solution time by“learning the measurement results”.The validation results illustrated that the predicted maximum relative errors of isentropic efficiency,corrected mass flow rate and corrected power are only 0.03%,0.22%and 0.26%respectively.The predicted flow distribution parameters in chamber,shroud cavity and outlet region of rotor are also basically consistent with the experimental results.In the chamber,it can be found that a pressure stagnation point is observed at circumferential angle of 270°when total pressure ratio is decreased.In the shroud cavity,obvious pressure variation is found near outlet of shroud cavity which although labyrinth seals exist.At outlet of rotor,obvious variations of velocity and pressure are found in the 0.0–0.4 and 0.6–0.8 of blade height.At the same time,obvious variations of velocity and pressure are found in the 0.0–0.4 and 0.6–0.8 of blade height and this is because the influence of upper passage vortex,lower passage vortex and end wall secondary flow.The present study can provide further reference for the dynamic performance evaluation of CAES radial inflow turbine.展开更多
基金supported by National Natural Science Foundation of China (No. 51806118)Foundation of LCP (No. 6142A0501020317)
文摘Solid oxide fuel cell(SOFC) vehicles are considered to have broad prospects for development, and the high operating temperature of SOFC results in great potential for waste-heat recovery. Many concepts for utilizing waste heat of SOFC have been suggested and studied, and most of them directly couple an SOFC to a gas turbine, which require the SOFC to operate at an elevated pressure and make the system less flexible and thus harder to operate. In recent years, with the development of turbine and heat exchanger technology, the supercritical carbon dioxide(S-CO_2) power cycle has raised widespread attractions for the waste recovery. This study explores the potential of S-CO_2 Brayton cycle to realize waste-heat recovery for an SOFC vehicle. The SOFC can operate at atmospheric pressure, and the hybrid system is easier to operate than the directly coupled systems. In this paper, a simple recuperated S-CO_2 Brayton cycle is proposed and the key component, radial inflow turbine is designed and focused. The flow state of the designed turbine is analyzed in detail based on computational fluid dynamics(CFD) numerical simulation. Five cases with different impeller tip clearances are numerically simulated to study its influence on the turbine performance. In addition, off-design performance analysis of the radial inflow turbine is conducted considering the temperature fluctuation of SOFC in practical applications.
基金supported by Strategic Priority Research Program of the Chinses Academy of Sciences(51925604)National Natural Science Foundation of China(51806211)The Science and Technology Foundation of Guizhou Province(No.[2019]1285).
文摘It is usually to conduct a full-scale three-dimensional flow analysis for a radial turbine to find a way to increase the efficiency of a Compressed Air Energy Storage(CAES)system.However,long solving time and huge consumption of computing resources become a major obstacle to the analysis.Therefore,in present study,a surrogate model with test data-based multi-layer perceptron(MLP)Neural Network is proposed to overcome the difficulty.Instead of complex flow field solving process,it provides reliable turbine aerodynamic performance and flow field distribution characteristics in a short solution time by“learning the measurement results”.The validation results illustrated that the predicted maximum relative errors of isentropic efficiency,corrected mass flow rate and corrected power are only 0.03%,0.22%and 0.26%respectively.The predicted flow distribution parameters in chamber,shroud cavity and outlet region of rotor are also basically consistent with the experimental results.In the chamber,it can be found that a pressure stagnation point is observed at circumferential angle of 270°when total pressure ratio is decreased.In the shroud cavity,obvious pressure variation is found near outlet of shroud cavity which although labyrinth seals exist.At outlet of rotor,obvious variations of velocity and pressure are found in the 0.0–0.4 and 0.6–0.8 of blade height.At the same time,obvious variations of velocity and pressure are found in the 0.0–0.4 and 0.6–0.8 of blade height and this is because the influence of upper passage vortex,lower passage vortex and end wall secondary flow.The present study can provide further reference for the dynamic performance evaluation of CAES radial inflow turbine.
