Permanent magnets with high energy products are widely used in a variety of electromagnetic devices. Such devices can be found in marine, aerospace, and robotic applications which require the minimization of weight an...Permanent magnets with high energy products are widely used in a variety of electromagnetic devices. Such devices can be found in marine, aerospace, and robotic applications which require the minimization of weight and volume of the electromagnetic device. During the magnetizing process, the magnet may not be perfectly magnetized. Therefore, it needs to be demagnetized. Because of high coercivity of some permanent magnets, the demagnetization process requires the intense magnetic fields in close proximity with the magnetic material. The fields must be produced for a short period of time （millisecond range） and they also must be bidirectional in order to overcome the coercivity of magnetic material. Different parameters have been known to affect the demagnetizer operation such as the core shape, core material, turn number, cross section of air gap, magnet type and so on. The amplitude and waveform of the fixture current is obtained from PSPICE simulations and also from experimental measurement. A 2D finite element analysis is developed to simulate the magnetic fields and the mechanical forces. In this paper, the main parameters affecting the optimal design of the demagnetizer are discussed. Simulation results show that the core structure, air gap width, and turn numbers are the most important parameters when designing such a device.展开更多
Centrifugal pumps are being widely used in many industrial and commercial applications.Many of these pumps are being operated at constant speed but could provide energy savings through adjustable speed operations.The ...Centrifugal pumps are being widely used in many industrial and commercial applications.Many of these pumps are being operated at constant speed but could provide energy savings through adjustable speed operations.The purpose of this study was to get the energy saving rates of the multistage centrifugal pump with variable speed conditions.For this investigation an experimental set up of variable flow and pressure system was made to get energy saving rates and numerical analyses are applied to validate the pump performance.The energy saving and therefore the cost saving depends on the specific duty cycle of which the machine operates.Duty cycle is the proportion of time during which a component,device and system is operated.The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time.The system was operated at 50%or less of the pump capacity.The input power of the system was carried out by pump characteristics curve of each operating point.The energy consumption was done by the product of specific duty cycle and the input power of the system for constant speed and variable speed drive operation.The total energy consumed for constant speed drive pump was 75,770 k W.hr and for variable speed drive pump was 31,700 k W.hr.The total energy saving of the system was 44,070 k W.hr or 58.16%annually.So,this paper suggests a method of implementing an energy saving on variable-flow and pressure system of the multistage centrifugal pump.展开更多
文摘Permanent magnets with high energy products are widely used in a variety of electromagnetic devices. Such devices can be found in marine, aerospace, and robotic applications which require the minimization of weight and volume of the electromagnetic device. During the magnetizing process, the magnet may not be perfectly magnetized. Therefore, it needs to be demagnetized. Because of high coercivity of some permanent magnets, the demagnetization process requires the intense magnetic fields in close proximity with the magnetic material. The fields must be produced for a short period of time （millisecond range） and they also must be bidirectional in order to overcome the coercivity of magnetic material. Different parameters have been known to affect the demagnetizer operation such as the core shape, core material, turn number, cross section of air gap, magnet type and so on. The amplitude and waveform of the fixture current is obtained from PSPICE simulations and also from experimental measurement. A 2D finite element analysis is developed to simulate the magnetic fields and the mechanical forces. In this paper, the main parameters affecting the optimal design of the demagnetizer are discussed. Simulation results show that the core structure, air gap width, and turn numbers are the most important parameters when designing such a device.
基金supported by the Korea government through the Korea institute of Energy Technology Evaluation and Planning(KETEP)The grant number is 20132010101870 for the Promotion of Science
文摘Centrifugal pumps are being widely used in many industrial and commercial applications.Many of these pumps are being operated at constant speed but could provide energy savings through adjustable speed operations.The purpose of this study was to get the energy saving rates of the multistage centrifugal pump with variable speed conditions.For this investigation an experimental set up of variable flow and pressure system was made to get energy saving rates and numerical analyses are applied to validate the pump performance.The energy saving and therefore the cost saving depends on the specific duty cycle of which the machine operates.Duty cycle is the proportion of time during which a component,device and system is operated.The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time.The system was operated at 50%or less of the pump capacity.The input power of the system was carried out by pump characteristics curve of each operating point.The energy consumption was done by the product of specific duty cycle and the input power of the system for constant speed and variable speed drive operation.The total energy consumed for constant speed drive pump was 75,770 k W.hr and for variable speed drive pump was 31,700 k W.hr.The total energy saving of the system was 44,070 k W.hr or 58.16%annually.So,this paper suggests a method of implementing an energy saving on variable-flow and pressure system of the multistage centrifugal pump.
