Synchronous machines are dedicated to the specific application. They are generally employed in rolling mills, pumps, fans, and compressors like reprobating and centrifugal drives, pulp and paper processing, water trea...Synchronous machines are dedicated to the specific application. They are generally employed in rolling mills, pumps, fans, and compressors like reprobating and centrifugal drives, pulp and paper processing, water treatment, mining, and in cement industries. As a synchronous motor, the performance is reduced for the given excitation while the load increases. When operated as synchronous generators, both power loads and lighting loads depend on the output from the armature winding. This paper presents an alternative choice in which by providing an additional winding in the stationary armature, when operated as a Double Winding Synchronous Motor (DWSyM), it becomes possible to operate in maximum power factor by adjusting the loads on both the stator windings. When operated as conventional motor, for the load current of 3.5 A, the efficiency is 55% and power factor is 0.55, for the same excitation when second winding is connected to a load current of 1 A, the efficiency is improved to 77.6% and power factor is improved to 0.66. The main focus of this machine is to improve the performance of the machine for the reduced excitation and minimum load. For the reduced excitation, the performance can be improved by loading both the windings. While operated as Double Winding Synchronous Generator (DWSyG), two stator outputs are available which help to separate the power and lighting circuits. Hence, interruption in the lighting circuit can be limited, this machine can be considered as Twin generator.展开更多
Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping unit...Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility, tremendous volume and weight in long stroke, etc.Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.展开更多
The nature of the exergy consumption of district heating(DH) systems can not be explained clearly using the first law of thermodynamics.Exergy analysis method was used.A case study based on a DH system in Inner Mongol...The nature of the exergy consumption of district heating(DH) systems can not be explained clearly using the first law of thermodynamics.Exergy analysis method was used.A case study based on a DH system in Inner Mongolia,China,was carried out.The impact of operating parameters and design parameters on the energy quality of circulating water and exergy losses of DH systems during heat distribution was revealed.Results show that the energy quality of circulating water and exergy losses of DH systems during heat distribution could be reduced by decreasing the indoor temperature or increasing radiator areas.Compared with other factors,the outdoor temperature and indoor temperature have a greater impact on the energy quality of circulating water,exergy losses of circulating water,and total exergy losses during heat distribution.When the outdoor temperature varied by 10.00%,the average variation rates of such parameters were 85.12%,90.02%,and 64.60%,respectively.When the outdoor temperature was 273.00 K and indoor temperature varied by 50.00%,the average variation rates of such parameters were 83.88%,99.34% and 32.87%,respectively.It can be observed that the energy quality and exergy losses of DH systems can be reduced in the operation process.展开更多
文摘Synchronous machines are dedicated to the specific application. They are generally employed in rolling mills, pumps, fans, and compressors like reprobating and centrifugal drives, pulp and paper processing, water treatment, mining, and in cement industries. As a synchronous motor, the performance is reduced for the given excitation while the load increases. When operated as synchronous generators, both power loads and lighting loads depend on the output from the armature winding. This paper presents an alternative choice in which by providing an additional winding in the stationary armature, when operated as a Double Winding Synchronous Motor (DWSyM), it becomes possible to operate in maximum power factor by adjusting the loads on both the stator windings. When operated as conventional motor, for the load current of 3.5 A, the efficiency is 55% and power factor is 0.55, for the same excitation when second winding is connected to a load current of 1 A, the efficiency is improved to 77.6% and power factor is improved to 0.66. The main focus of this machine is to improve the performance of the machine for the reduced excitation and minimum load. For the reduced excitation, the performance can be improved by loading both the windings. While operated as Double Winding Synchronous Generator (DWSyG), two stator outputs are available which help to separate the power and lighting circuits. Hence, interruption in the lighting circuit can be limited, this machine can be considered as Twin generator.
文摘Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility, tremendous volume and weight in long stroke, etc.Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.
基金Project(51408184)supported by the National Natural Science Foundation of ChinaProject(15JCQNJC07800)supported by Tianjin Natural Science Foundation,ChinaProject(YQ2014005)supported by Excellent Young Foundation of Hebei Educational Committee,China
文摘The nature of the exergy consumption of district heating(DH) systems can not be explained clearly using the first law of thermodynamics.Exergy analysis method was used.A case study based on a DH system in Inner Mongolia,China,was carried out.The impact of operating parameters and design parameters on the energy quality of circulating water and exergy losses of DH systems during heat distribution was revealed.Results show that the energy quality of circulating water and exergy losses of DH systems during heat distribution could be reduced by decreasing the indoor temperature or increasing radiator areas.Compared with other factors,the outdoor temperature and indoor temperature have a greater impact on the energy quality of circulating water,exergy losses of circulating water,and total exergy losses during heat distribution.When the outdoor temperature varied by 10.00%,the average variation rates of such parameters were 85.12%,90.02%,and 64.60%,respectively.When the outdoor temperature was 273.00 K and indoor temperature varied by 50.00%,the average variation rates of such parameters were 83.88%,99.34% and 32.87%,respectively.It can be observed that the energy quality and exergy losses of DH systems can be reduced in the operation process.
