One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temper...One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temperature and pressure along the height in the two converters, respectively. Design optimization methods of the two converters have been proposed, by which the minimum catalyst volume can be obtained to satisfy the productive capacity of 1000 tons per day, when the operating pressure is 15.0, 10.0 and 7.5 MPa, respectively.展开更多
As potential alternative power sources used in portable electric generators, opposite axial piston engines in small-scale were investigated to show their advantages in power density. A novel cylinder charge system was...As potential alternative power sources used in portable electric generators, opposite axial piston engines in small-scale were investigated to show their advantages in power density. A novel cylinder charge system was introduced, based on which a quasi-dimension model and a CFD(computational fluid dynamics) model were established. Comparison of those two models was carried out to validate the quasi-dimension model. Furthermore, optimal diameter of charge cylinder and speed were determined after evaluating the quasi-dimension model based on different parameters. High agreement between the quasi-dimension model and the CFD model validates the quasi-dimension model. Further studies show that the power of engine increases with the diameter of charge cylinder. However, a too big charge cylinder lowers the fuel efficiency instead. Taking economic influence into consideration the charge cylinder should be 1.4 times power cylinder, which could ensure the power density, volumetric efficiency and fuel economic at the same time. Axial piston engine running at 1.0×104 r/min could achieve a better overall performance. The maximal power of engine with optimal parameters is 0.82 k W, which fits the power need of the portable electric generators completely.展开更多
A multidisciplinary optimization was conducted to simultaneously improve the efficiency and reduce the radial force of a single-channel pump for wastewater treatment. A hybrid multi-objective evolutionary algorithm wa...A multidisciplinary optimization was conducted to simultaneously improve the efficiency and reduce the radial force of a single-channel pump for wastewater treatment. A hybrid multi-objective evolutionary algorithm was coupled with a surrogate model to optimize the geometry of the single-channel pump volute. Steady and unsteady Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were discretized using finite volume approximations and were then solved on tetrahedral grids to analyze the flow in the single-channel pump. The three objective functions represented the total efficiency, the sweep area of the radial force during one revolution, and the distance of the mass center of sweep area from the origin while the two design variables were related to the cross-sectional area of the internal flow of the volute. Latin hypercube sampling was employed to generate twelve design points within the design space, and response surface approximation models were constructed as surrogate models for the objectives based on the values of the objective function at the given design points. A fast non-dominated sorting genetic algorithm for local search was coupled with the surrogate models to determine the global Pareto-optimal solutions. The trade-off between the objectives was determined and was described in terms of the Pareto-optimal solutions. The results of the multi-objective optimization showed that the optimum design simultaneously improved the efficiency and reduced the radial force relative to those of the reference design.展开更多
The inlet attack angle of rotor blade reasonably can be adjusted with the change of the stagger angle of inlet guide vane (IGV); so the efficiency of each condition will be affected. For the purpose to improve the eff...The inlet attack angle of rotor blade reasonably can be adjusted with the change of the stagger angle of inlet guide vane (IGV); so the efficiency of each condition will be affected. For the purpose to improve the efficiency, the DSP (Digital Signal Processor) controller is designed to adjust the stagger angle of IGV automatically in order to optimize the efficiency at any operating condition. The A/D signal collection includes inlet static pressure, outlet static pressure, outlet total pressure, rotor speed and torque signal, the efficiency can be calculated in the DSP, and the angle signal for the stepping motor which control the IGV will be sent out from the D/A. Experimental investigations are performed in a three-stage, low-speed axial compressor with variable inlet guide vanes. It is demonstrated that the DSP designed can well adjust the stagger angle of IGV online, the efficiency under different conditions can be optimized. This establishment of DSP online adjustment scheme may provide a practical solution for improving performance of multi-stage axial flow compressor when its operating condition is varied.展开更多
文摘One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temperature and pressure along the height in the two converters, respectively. Design optimization methods of the two converters have been proposed, by which the minimum catalyst volume can be obtained to satisfy the productive capacity of 1000 tons per day, when the operating pressure is 15.0, 10.0 and 7.5 MPa, respectively.
基金Projects(51475464,51175500) supported by the National Natural Science Foundation of China
文摘As potential alternative power sources used in portable electric generators, opposite axial piston engines in small-scale were investigated to show their advantages in power density. A novel cylinder charge system was introduced, based on which a quasi-dimension model and a CFD(computational fluid dynamics) model were established. Comparison of those two models was carried out to validate the quasi-dimension model. Furthermore, optimal diameter of charge cylinder and speed were determined after evaluating the quasi-dimension model based on different parameters. High agreement between the quasi-dimension model and the CFD model validates the quasi-dimension model. Further studies show that the power of engine increases with the diameter of charge cylinder. However, a too big charge cylinder lowers the fuel efficiency instead. Taking economic influence into consideration the charge cylinder should be 1.4 times power cylinder, which could ensure the power density, volumetric efficiency and fuel economic at the same time. Axial piston engine running at 1.0×104 r/min could achieve a better overall performance. The maximal power of engine with optimal parameters is 0.82 k W, which fits the power need of the portable electric generators completely.
文摘A multidisciplinary optimization was conducted to simultaneously improve the efficiency and reduce the radial force of a single-channel pump for wastewater treatment. A hybrid multi-objective evolutionary algorithm was coupled with a surrogate model to optimize the geometry of the single-channel pump volute. Steady and unsteady Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were discretized using finite volume approximations and were then solved on tetrahedral grids to analyze the flow in the single-channel pump. The three objective functions represented the total efficiency, the sweep area of the radial force during one revolution, and the distance of the mass center of sweep area from the origin while the two design variables were related to the cross-sectional area of the internal flow of the volute. Latin hypercube sampling was employed to generate twelve design points within the design space, and response surface approximation models were constructed as surrogate models for the objectives based on the values of the objective function at the given design points. A fast non-dominated sorting genetic algorithm for local search was coupled with the surrogate models to determine the global Pareto-optimal solutions. The trade-off between the objectives was determined and was described in terms of the Pareto-optimal solutions. The results of the multi-objective optimization showed that the optimum design simultaneously improved the efficiency and reduced the radial force relative to those of the reference design.
基金supported by National Basic Research Program of China 2007CB210104National Natural Science Foundation of China with projects No.51010007.and No.50736007
文摘The inlet attack angle of rotor blade reasonably can be adjusted with the change of the stagger angle of inlet guide vane (IGV); so the efficiency of each condition will be affected. For the purpose to improve the efficiency, the DSP (Digital Signal Processor) controller is designed to adjust the stagger angle of IGV automatically in order to optimize the efficiency at any operating condition. The A/D signal collection includes inlet static pressure, outlet static pressure, outlet total pressure, rotor speed and torque signal, the efficiency can be calculated in the DSP, and the angle signal for the stepping motor which control the IGV will be sent out from the D/A. Experimental investigations are performed in a three-stage, low-speed axial compressor with variable inlet guide vanes. It is demonstrated that the DSP designed can well adjust the stagger angle of IGV online, the efficiency under different conditions can be optimized. This establishment of DSP online adjustment scheme may provide a practical solution for improving performance of multi-stage axial flow compressor when its operating condition is varied.
