It is the purpose of the present paper to convert hydraulic energy to electric energy and saves both the pressure and electrical energy for re - use during the next system upstroke using two secondary units coupled to...It is the purpose of the present paper to convert hydraulic energy to electric energy and saves both the pressure and electrical energy for re - use during the next system upstroke using two secondary units coupled to induction motor to drive cylinder loads. During upstroke operation, the variable pump/motor （P/M） driven by both electric motor and the second （P/M） works as hydraulic pump and output flow to the cylinders which drive the load. During load deceleration, the cylinders work as pump while the operation of the two secondary units are reversed, the variable （P/M） works as a motor generating a torque with the electric motor to drive the other （P/M） which transforms mechanical energy to hydraulic energy that is saved in the accumulator. When the energy storage capacity of the accumulator is attained as the operation continues, energy storage to the accumulator is thermostatically stopped while the induction motor begins to work as a generator and generates electricity that is stored in the power distribution unit. Simulations were performed using a limited PT2 Block, i.e. 2nd-order transfer function with limitation of slope and signal output to determine suitable velocity of the cylinder which will match high performance and system stability. A mathematical model suited to the simulation of the hydraulic accumulator both in an open-or close-loop system is presented. The quest for improvement of lower energy capacity storage, saving and re-utilization of the conventional accumulator resulting in the short cycle time usage of hydraulic accumulators both in domestic and industrial purposes necessitates this research. The outcome of the research appears to be very efficient for generating fluctuation free electricity, power quality and reliability, energy saving/reutilization and system noise reduction.展开更多
This paper describes the design and implementation of a hydraulic circuit design system using case-based reasoning (CBR) paradigm from AI community The domain of hydraulic circuit design and case-based reasoning are ...This paper describes the design and implementation of a hydraulic circuit design system using case-based reasoning (CBR) paradigm from AI community The domain of hydraulic circuit design and case-based reasoning are briefly reviewed Then a proposed methodology in compuer-aided circuit design and dynamic leaning with the use of CBR is described Finally an application example is selected to illustrate the ussfulness of applying CBR in hydraulic circuit design with leaming.展开更多
At present,the over-travel measurement of high-voltage circuit breakers is mostly carried out after the circuit breaker is completely dismantled.The disadvantage of the measurement is that it can only be measured when...At present,the over-travel measurement of high-voltage circuit breakers is mostly carried out after the circuit breaker is completely dismantled.The disadvantage of the measurement is that it can only be measured when the circuit breaker is dismantled and overhauled.Defects are diagnosed in a timely and effective manner,and capacity causes hidden troubles.This article provides a method for direct measurement of hydraulic circuit breakers without any adjustment or disassembly.The method can be carried out in various situations such as minor repairs,major repairs,and temporary repairs,which not only saves time,but also improves accuracy of the measurement.The comparative test results show that this method can be simple,convenient and effective to measure the overtravel of the high-voltage circuit breaker.展开更多
High voltage circuit breakers are the most important protection and control apparatus in power system. As a core part of circuit breakers, the operating mechanisms have a trend to be hydraulic-style in high voltage po...High voltage circuit breakers are the most important protection and control apparatus in power system. As a core part of circuit breakers, the operating mechanisms have a trend to be hydraulic-style in high voltage power grid. Compared with other hydranlic systems, the hydraulic operating mechanisms have the characteristics of high hydraulic pressure, high speed, high power and long-term waiting etc., and it is because of the characteristics that the hydraulic operating mechanisms become dif- ficult to be developed and have been arousing significant study interest from more and more researchers as well as their promising applications. Therefore, it is significant to summarize the hydraulic operating mechanisms on their development, characteristics, and key technologies etc. In this review, the evolution process and recent studies of hydraulic operating mechanisms at home and abroad are viewed. The review then focuses on the characteristics and key technologies of hydraulic operating mechanisms, especially on time and velocity characteristics, high-speed cylinder cushioning, fast response and great flow rate control valve, temperature compensation, system monitoring and fault diagnosis, intelligent operation, energy storage module, etc. In the end, the future trends of this field are presented.展开更多
The Printed Circuit Heat Exchanger(PCHE) is one of the most promising heat exchangers for Synergetic Air-breathing and Rocket Engine(SABRE). To reduce pressure drop and improve compactness, the micron-sized PCHE made ...The Printed Circuit Heat Exchanger(PCHE) is one of the most promising heat exchangers for Synergetic Air-breathing and Rocket Engine(SABRE). To reduce pressure drop and improve compactness, the micron-sized PCHE made up of rectangular channels of tens of microns in size, is used in SABRE. In present work, we focus on thermal-hydraulic-structural characteristics of micron-sized PCHE by conducting three-dimensional(3-D) numerical simulation. Helium and hydrogen are employed as the working fluids and the Stainless Steel 316(SS316) as the solid substrate. The thermal-hydraulic performance of the micron-sized PCHE is discussed by using the commercial Computational Fluid Dynamics(CFD) software of Fluent. ANSYSMechanical is also employed to simulate stress field of representative PCHE channels. The mechanical stress induced by pressure loading and the thermal stress induced by temperature gradient are found to be equally important sources of stress. To improve comprehensive performances of micron-sized PCHE, two types of channel arrangements and different channel aspect ratios are studied. The double banking is of higher thermal-hydraulic performance compared to the single banking while the stress performance is identical for the two modes. Meanwhile, the effect of channel aspect ratio is investigated by comparing thermal-hydraulic characteristics and structural stress of the model. The rectangular channel with w/h=2 achieves the most balanced stress characteristic and higher thermal-hydraulic performance.展开更多
文摘It is the purpose of the present paper to convert hydraulic energy to electric energy and saves both the pressure and electrical energy for re - use during the next system upstroke using two secondary units coupled to induction motor to drive cylinder loads. During upstroke operation, the variable pump/motor （P/M） driven by both electric motor and the second （P/M） works as hydraulic pump and output flow to the cylinders which drive the load. During load deceleration, the cylinders work as pump while the operation of the two secondary units are reversed, the variable （P/M） works as a motor generating a torque with the electric motor to drive the other （P/M） which transforms mechanical energy to hydraulic energy that is saved in the accumulator. When the energy storage capacity of the accumulator is attained as the operation continues, energy storage to the accumulator is thermostatically stopped while the induction motor begins to work as a generator and generates electricity that is stored in the power distribution unit. Simulations were performed using a limited PT2 Block, i.e. 2nd-order transfer function with limitation of slope and signal output to determine suitable velocity of the cylinder which will match high performance and system stability. A mathematical model suited to the simulation of the hydraulic accumulator both in an open-or close-loop system is presented. The quest for improvement of lower energy capacity storage, saving and re-utilization of the conventional accumulator resulting in the short cycle time usage of hydraulic accumulators both in domestic and industrial purposes necessitates this research. The outcome of the research appears to be very efficient for generating fluctuation free electricity, power quality and reliability, energy saving/reutilization and system noise reduction.
文摘This paper describes the design and implementation of a hydraulic circuit design system using case-based reasoning (CBR) paradigm from AI community The domain of hydraulic circuit design and case-based reasoning are briefly reviewed Then a proposed methodology in compuer-aided circuit design and dynamic leaning with the use of CBR is described Finally an application example is selected to illustrate the ussfulness of applying CBR in hydraulic circuit design with leaming.
文摘At present,the over-travel measurement of high-voltage circuit breakers is mostly carried out after the circuit breaker is completely dismantled.The disadvantage of the measurement is that it can only be measured when the circuit breaker is dismantled and overhauled.Defects are diagnosed in a timely and effective manner,and capacity causes hidden troubles.This article provides a method for direct measurement of hydraulic circuit breakers without any adjustment or disassembly.The method can be carried out in various situations such as minor repairs,major repairs,and temporary repairs,which not only saves time,but also improves accuracy of the measurement.The comparative test results show that this method can be simple,convenient and effective to measure the overtravel of the high-voltage circuit breaker.
基金This work was supported by the National High Technology Research and Development Program of China (Grant No.2007AA041803)Doctoral.Programs Foundation of Ministry of Education of China (Grant No.20090101110041)Program for New Century Excellent Talents in University
文摘High voltage circuit breakers are the most important protection and control apparatus in power system. As a core part of circuit breakers, the operating mechanisms have a trend to be hydraulic-style in high voltage power grid. Compared with other hydranlic systems, the hydraulic operating mechanisms have the characteristics of high hydraulic pressure, high speed, high power and long-term waiting etc., and it is because of the characteristics that the hydraulic operating mechanisms become dif- ficult to be developed and have been arousing significant study interest from more and more researchers as well as their promising applications. Therefore, it is significant to summarize the hydraulic operating mechanisms on their development, characteristics, and key technologies etc. In this review, the evolution process and recent studies of hydraulic operating mechanisms at home and abroad are viewed. The review then focuses on the characteristics and key technologies of hydraulic operating mechanisms, especially on time and velocity characteristics, high-speed cylinder cushioning, fast response and great flow rate control valve, temperature compensation, system monitoring and fault diagnosis, intelligent operation, energy storage module, etc. In the end, the future trends of this field are presented.
基金supported by the National Key Research and Development Program of China under grant number 2017YFB0601803the National Natural Science Foundation of China under grant number 51576156the 111 Project under grant number B16038
文摘The Printed Circuit Heat Exchanger(PCHE) is one of the most promising heat exchangers for Synergetic Air-breathing and Rocket Engine(SABRE). To reduce pressure drop and improve compactness, the micron-sized PCHE made up of rectangular channels of tens of microns in size, is used in SABRE. In present work, we focus on thermal-hydraulic-structural characteristics of micron-sized PCHE by conducting three-dimensional(3-D) numerical simulation. Helium and hydrogen are employed as the working fluids and the Stainless Steel 316(SS316) as the solid substrate. The thermal-hydraulic performance of the micron-sized PCHE is discussed by using the commercial Computational Fluid Dynamics(CFD) software of Fluent. ANSYSMechanical is also employed to simulate stress field of representative PCHE channels. The mechanical stress induced by pressure loading and the thermal stress induced by temperature gradient are found to be equally important sources of stress. To improve comprehensive performances of micron-sized PCHE, two types of channel arrangements and different channel aspect ratios are studied. The double banking is of higher thermal-hydraulic performance compared to the single banking while the stress performance is identical for the two modes. Meanwhile, the effect of channel aspect ratio is investigated by comparing thermal-hydraulic characteristics and structural stress of the model. The rectangular channel with w/h=2 achieves the most balanced stress characteristic and higher thermal-hydraulic performance.
