The performance of proton exchange membrane fuel cells is very sensitive to temperature. The electrochemical reaction results directly in temperature variations in the proton exchange membrane fuel cell. Ensuring effe...The performance of proton exchange membrane fuel cells is very sensitive to temperature. The electrochemical reaction results directly in temperature variations in the proton exchange membrane fuel cell. Ensuring effective temperature control is crucial to ensure fuel cell reliability and durability. This paper uses active disturbance rejection control in the thermal management system to maintain the operating temperature and the stack inlet and outlet temperature difference at the set value. First, key cooling system modules such as expansion tanks, coolant circulation pumps and radiators based on Simulink were built. Then, physical modeling and simulation of the fuel cell cooling system was carried out. In order to ensure the effectiveness of the control strategy and reduce the parameter tuning workload, an active disturbance rejection control parameter optimization method using an elite genetic algorithm was proposed. When the optimized control strategy responds to input disturbances, the maximum overshoot of the system is only 1.23% and can reach stability again in 30 s, so the fuel cell temperature can be controlled effectively. Simulation results show that the optimized control strategy can effectively control the stack temperature and coolant temperature difference under the influence of stepped charging current without interference or with interference, and has strong robustness and anti-interference capability.展开更多
Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on ...Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on hydrodynamic characteristics of pump and the mechanism. However, the existing studies are limited to investigate the influence of only one or two volute geometrical parameters each time, and a systematic study of the influence of the combinations of different volute geometrical parameters on the pump's hydrodynamic characteristics is missing. In this paper, a study on the understanding of the influence of volute geometrical variations on hydrodynamic characteristics of a high speed circulator pump by using computational fluid dynamics(CFD) technology is presented. Five main volute geometrical parameters D3, A8, a0, j0 and Rt are selected and 25 different volute configurations are generated by using design of experiments(DOE) method. The 3D unsteady flow numerical simulations, which are based on the SST k-w turbulence model and sliding mesh technique provided by CFX, are executed on the 25 different volute configurations. The hydraulic performance, pressure pulsation and unsteady radial force inside the pump at design condition are obtained and analyzed. It has been found that volute geometrical parameters D3 and A8 are major influence factors on hydrodynamic characteristics of the pump, while a0, j0 and Rt are minor influence factors. The minimum contribution from both D3 and A8 is 58% on head, and maximum contribution from both D3 and A8 is 90% on pressure pulsation. Regarding the pressure pulsation intensity, two peaks can be found. One is in the tongue area and the other is in the diffusor area. The contributions are around 60% from tongue and 25% from diffusor, respectively. The amplitude of pressure pulsation has a quadratic polynomial functional relationship with respect to D3/D2 and A8/A(10), and fluctuating level of radial force has a quadratic polynomial functional relationship with respect to D3/D2. While for the other volute parameters a0, j0 and Rt, no special function has been found related to pressure pulsation and radial force. The presented work could be a useful guideline in engineering practice when designing a circulator pump with low hydrodynamic force.展开更多
The superconducting magnet of Central Solenoid(CS) model coil of China Fusion Engineering Test Reactor(CFETR) is made of Nb_3Sn/Nb Ti cable-in-conduit conductor(CICC),and operated by forced-flow cooling with a l...The superconducting magnet of Central Solenoid(CS) model coil of China Fusion Engineering Test Reactor(CFETR) is made of Nb_3Sn/Nb Ti cable-in-conduit conductor(CICC),and operated by forced-flow cooling with a large amount of supercritical helium.The cryogenic circulation pump is analyzed and considered to be effective in achieving the supercritical helium(SHe) circulation for the forced-flow cooled(FFC) CICC magnet.A distributed system will be constructed for cooling the CFETR CS model coil.This paper presents the design of FFC process for the CFETR CS model coil.The equipment configuration,quench protection in the magnet and the process control are presented.展开更多
New design solutions have been proposed for a BRS-GPG type reactor circuit, which are different from transport and stationary low and medium-powered reactor installations cooled with heavy liquid-metal coolants, and w...New design solutions have been proposed for a BRS-GPG type reactor circuit, which are different from transport and stationary low and medium-powered reactor installations cooled with heavy liquid-metal coolants, and which correspond to the evolutionary development of such installations. While developing these solutions, the available experience in creating and operating So</span><span>viet pilot and commercial power plants cooled with lead-bismuth coolants</span><span> was used, including investigations, primarily experimental ones, carried out by team of authors in justification of a capacity range (50</span></span><span> </span><span>-</span><span> </span><span>250 MW) of low and medium-powered reactor plants with horizontal steam generators (BRS-</span><span> </span><span>GPG) proposed and elaborated at the NNSTU.展开更多
When regulating a pipe network according to user demand,hydraulic balance and power consumption are crucial factors for a multi-source looped-pipe network applying distributed variable-speed pumps compared to the conv...When regulating a pipe network according to user demand,hydraulic balance and power consumption are crucial factors for a multi-source looped-pipe network applying distributed variable-speed pumps compared to the conventional central circulating pump system.In this paper,the influence of the fill point on power consumption and hydraulic balance of the multi-source looped-pipe network was studied.A mathematical model for electricity energy consumption analysis was built and calculated for a large sized looped-pipe network with multiple heat sources and distributed variable-speed pumps.The hydraulic calculation models of each single element,such as pipe,distribution pump,valve,replenishment pump,heat source and substation,were built.A case located in Dezhou city,China was analyzed.The results showed that:the maximum power saving(39.2%)could be achieved when each heat source had its own fill point,but the heat sources would not meet their design flows;to meet the design flows of all the heat sources,only one fill point should be necessarily located near the heat source with the lowest flow rate to get the expected hydraulic stability and energy saving.展开更多
Modeling and simulation of thermal-fluid systems are very important in industrial numerical simulation and play key roles in their design and control. In this paper, the modeling and simplification method of one-dimen...Modeling and simulation of thermal-fluid systems are very important in industrial numerical simulation and play key roles in their design and control. In this paper, the modeling and simplification method of one-dimensional thermal-fluid network with variable-property are presented, including matrix representation of the network, simplification algorithm for series/parallel connection based on matrix operation and generation of flow equations based on system topology. This simplification is suitable for the simulation of thermal-fluid systems with arbitrary topological structure. The method to treat reflux during iteration is proposed. The outstanding features of the simplification algorithm are the significant reduction in the thermal-fluid network and therefore the number of the related governing equations, as well as the computation burden. The example in this paper shows that the number of the governing equations for flow is reduced by about 45% and the calculation time of flow calculation is reduced by an average of 32% after the simplification.展开更多
文摘The performance of proton exchange membrane fuel cells is very sensitive to temperature. The electrochemical reaction results directly in temperature variations in the proton exchange membrane fuel cell. Ensuring effective temperature control is crucial to ensure fuel cell reliability and durability. This paper uses active disturbance rejection control in the thermal management system to maintain the operating temperature and the stack inlet and outlet temperature difference at the set value. First, key cooling system modules such as expansion tanks, coolant circulation pumps and radiators based on Simulink were built. Then, physical modeling and simulation of the fuel cell cooling system was carried out. In order to ensure the effectiveness of the control strategy and reduce the parameter tuning workload, an active disturbance rejection control parameter optimization method using an elite genetic algorithm was proposed. When the optimized control strategy responds to input disturbances, the maximum overshoot of the system is only 1.23% and can reach stability again in 30 s, so the fuel cell temperature can be controlled effectively. Simulation results show that the optimized control strategy can effectively control the stack temperature and coolant temperature difference under the influence of stepped charging current without interference or with interference, and has strong robustness and anti-interference capability.
基金Supported by National Natural Science Foundation of China(Grant No.51239005)Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LQ15E090004,LQ15E090005)Project of Zhejiang Education,China(Grant No.Y201432222)
文摘Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on hydrodynamic characteristics of pump and the mechanism. However, the existing studies are limited to investigate the influence of only one or two volute geometrical parameters each time, and a systematic study of the influence of the combinations of different volute geometrical parameters on the pump's hydrodynamic characteristics is missing. In this paper, a study on the understanding of the influence of volute geometrical variations on hydrodynamic characteristics of a high speed circulator pump by using computational fluid dynamics(CFD) technology is presented. Five main volute geometrical parameters D3, A8, a0, j0 and Rt are selected and 25 different volute configurations are generated by using design of experiments(DOE) method. The 3D unsteady flow numerical simulations, which are based on the SST k-w turbulence model and sliding mesh technique provided by CFX, are executed on the 25 different volute configurations. The hydraulic performance, pressure pulsation and unsteady radial force inside the pump at design condition are obtained and analyzed. It has been found that volute geometrical parameters D3 and A8 are major influence factors on hydrodynamic characteristics of the pump, while a0, j0 and Rt are minor influence factors. The minimum contribution from both D3 and A8 is 58% on head, and maximum contribution from both D3 and A8 is 90% on pressure pulsation. Regarding the pressure pulsation intensity, two peaks can be found. One is in the tongue area and the other is in the diffusor area. The contributions are around 60% from tongue and 25% from diffusor, respectively. The amplitude of pressure pulsation has a quadratic polynomial functional relationship with respect to D3/D2 and A8/A(10), and fluctuating level of radial force has a quadratic polynomial functional relationship with respect to D3/D2. While for the other volute parameters a0, j0 and Rt, no special function has been found related to pressure pulsation and radial force. The presented work could be a useful guideline in engineering practice when designing a circulator pump with low hydrodynamic force.
文摘The superconducting magnet of Central Solenoid(CS) model coil of China Fusion Engineering Test Reactor(CFETR) is made of Nb_3Sn/Nb Ti cable-in-conduit conductor(CICC),and operated by forced-flow cooling with a large amount of supercritical helium.The cryogenic circulation pump is analyzed and considered to be effective in achieving the supercritical helium(SHe) circulation for the forced-flow cooled(FFC) CICC magnet.A distributed system will be constructed for cooling the CFETR CS model coil.This paper presents the design of FFC process for the CFETR CS model coil.The equipment configuration,quench protection in the magnet and the process control are presented.
文摘New design solutions have been proposed for a BRS-GPG type reactor circuit, which are different from transport and stationary low and medium-powered reactor installations cooled with heavy liquid-metal coolants, and which correspond to the evolutionary development of such installations. While developing these solutions, the available experience in creating and operating So</span><span>viet pilot and commercial power plants cooled with lead-bismuth coolants</span><span> was used, including investigations, primarily experimental ones, carried out by team of authors in justification of a capacity range (50</span></span><span> </span><span>-</span><span> </span><span>250 MW) of low and medium-powered reactor plants with horizontal steam generators (BRS-</span><span> </span><span>GPG) proposed and elaborated at the NNSTU.
基金This work is supported by the National Program on Key Basic Research Project of China(973 Program)(Grant No.2014CB249201).
文摘When regulating a pipe network according to user demand,hydraulic balance and power consumption are crucial factors for a multi-source looped-pipe network applying distributed variable-speed pumps compared to the conventional central circulating pump system.In this paper,the influence of the fill point on power consumption and hydraulic balance of the multi-source looped-pipe network was studied.A mathematical model for electricity energy consumption analysis was built and calculated for a large sized looped-pipe network with multiple heat sources and distributed variable-speed pumps.The hydraulic calculation models of each single element,such as pipe,distribution pump,valve,replenishment pump,heat source and substation,were built.A case located in Dezhou city,China was analyzed.The results showed that:the maximum power saving(39.2%)could be achieved when each heat source had its own fill point,but the heat sources would not meet their design flows;to meet the design flows of all the heat sources,only one fill point should be necessarily located near the heat source with the lowest flow rate to get the expected hydraulic stability and energy saving.
文摘Modeling and simulation of thermal-fluid systems are very important in industrial numerical simulation and play key roles in their design and control. In this paper, the modeling and simplification method of one-dimensional thermal-fluid network with variable-property are presented, including matrix representation of the network, simplification algorithm for series/parallel connection based on matrix operation and generation of flow equations based on system topology. This simplification is suitable for the simulation of thermal-fluid systems with arbitrary topological structure. The method to treat reflux during iteration is proposed. The outstanding features of the simplification algorithm are the significant reduction in the thermal-fluid network and therefore the number of the related governing equations, as well as the computation burden. The example in this paper shows that the number of the governing equations for flow is reduced by about 45% and the calculation time of flow calculation is reduced by an average of 32% after the simplification.