With the advantages of high reliability, power density, and long life, nuclear power reactors have become a promising option for space power. In this study, the Reactor Excursion and Leak Analysis Program 5(RELAP5), w...With the advantages of high reliability, power density, and long life, nuclear power reactors have become a promising option for space power. In this study, the Reactor Excursion and Leak Analysis Program 5(RELAP5), with the implementation of sodium–potassium eutectic alloy(NaK-78) properties and heat transfer correlations, is adopted to analyze the thermal–hydraulic characteristics of the space nuclear reactor TOPAZ-Ⅱ.A RELAP5 model including thermionic fuel elements(TFEs), reactor core, radiator, coolant loop, and volume accumulator is established. The temperature reactivity feedback effects of the fuel, TFE emitter, TFE collector,moderator, and reactivity insertion effects of the control drums and safety drums are considered. To benchmark the integrated TOPAZ-Ⅱ system model, an electrical ground test of the fully integrated TOPAZ-Ⅱ system, the V-71 unit,is simulated and analyzed. The calculated coolant temperature and system pressure are in acceptable agreement with the experimental data for the maximum relative errors of 8 and 10%, respectively. The detailed thermal–hydraulic characteristics of TOPAZ-Ⅱ are then simulated and analyzed at the steady state. The calculation results agree well with the design values. The current work provides a solid foundation for space reactor design and transient analysis in the future.展开更多
An anaerobic baffled reactor is a system developed in recent decades and has been used as part of the treatment of high-strength wastewater. Since the function of this system is based on its hydrodynamic features, hyd...An anaerobic baffled reactor is a system developed in recent decades and has been used as part of the treatment of high-strength wastewater. Since the function of this system is based on its hydrodynamic features, hydrodynamics and the regime of the flow through the reactor are crucial. In this study, a prototype reactor with eight chambers, which had a total volume of 48 L, and a model reactor, whose dimensions were half of those of the prototype reactor, were used. The Froude dynamic similitude in these reactors was investigated. The results show that the curve dimensionless variances were 0.089 and 0.096 for the prototype and model reactors, respectively, the short-circuiting indices were 0.483 and 0.489 for the prototype and model reactors, respectively, the effective volume and short-circuiting index measurement errors were both 1%, the hydraulic efficiency error was 2%, and the Peclet and dispersion number errors were both 7%. Most of the compared indices were close to one another in value. Therefore, the model reactor can be used based on the Froude dynamic similitude to determine hydrodynamic charac-teristics of a baffled reactor at a full scale.展开更多
Periodic anaerobic baffled reactor （PABR） is a novel reactor based on the design concept of anaerobic baffled reactor （ABR）. Residence time distribution （RTD） studies on both clean and working reactors at the sa...Periodic anaerobic baffled reactor （PABR） is a novel reactor based on the design concept of anaerobic baffled reactor （ABR）. Residence time distribution （RTD） studies on both clean and working reactors at the same hydraulic residence time （HRT） of 2 d were carded out to investigate the dead spaces and mixing patterns in PABRs at different organic loading rates （OLRs） in various switching manners and frequencies. The results showed that the fraction of dead space in PABR was similar to that in ABR, which was low in comparison with other reactor designs. Dead space may be divided into two categories, hydraulic and biological. In RTD studies without biomass, the hydraulic dead space in the PABR run in an ＂every second＂ switching manner with T = 2 d was the lowest whereas that in the PABR run in a T = ∞ （ABR） switching manner was the highest. The same trend was obtained with the total dead space in RTD studies with biomass no matter what the OLR was. Biological dead space was the major contributor to dead space but affected decreasingly at higher OLR whichever switching manner the PABR run in. The flow patterns within the PABRs were intermediate between plug-flow and perfectly mixed under all the conditions tested,展开更多
Anaerobic expanded bed reactor(AEBR) is mostly used for the treatment of fairly low strength wastewaters. Since the performance of AEBR largely depends on its hydraulic characteristics, residence time distribution(RTD...Anaerobic expanded bed reactor(AEBR) is mostly used for the treatment of fairly low strength wastewaters. Since the performance of AEBR largely depends on its hydraulic characteristics, residence time distribution(RTD) method is commonly used for investigation of the hydraulic characteristics of AEBR under different ascending velocity of mixed liquor. In this paper, a pilot-scale AEBR reactor is investigated for treatment of municipal sewage in which lithium chloride is used as a tracer. The results show that the AEBR could be considered as the superimposition of several constant stirred tank reactors(CSTR) and the increase of hydraulic up-flow velocity could increase the number of the CSTR and decrease the volume rate of the dead zone. The optimal up-flow velocity of the investigated AEBR was approximately 1.9 m/h in the municipal sewage treatment.展开更多
基金supported by the China National Postdoctoral Program for Innovative Talents(No.BX201600124)China Postdoctoral Science Foundation(No.2016M600796)the National Natural Science Foundation of China(No.11605131)
文摘With the advantages of high reliability, power density, and long life, nuclear power reactors have become a promising option for space power. In this study, the Reactor Excursion and Leak Analysis Program 5(RELAP5), with the implementation of sodium–potassium eutectic alloy(NaK-78) properties and heat transfer correlations, is adopted to analyze the thermal–hydraulic characteristics of the space nuclear reactor TOPAZ-Ⅱ.A RELAP5 model including thermionic fuel elements(TFEs), reactor core, radiator, coolant loop, and volume accumulator is established. The temperature reactivity feedback effects of the fuel, TFE emitter, TFE collector,moderator, and reactivity insertion effects of the control drums and safety drums are considered. To benchmark the integrated TOPAZ-Ⅱ system model, an electrical ground test of the fully integrated TOPAZ-Ⅱ system, the V-71 unit,is simulated and analyzed. The calculated coolant temperature and system pressure are in acceptable agreement with the experimental data for the maximum relative errors of 8 and 10%, respectively. The detailed thermal–hydraulic characteristics of TOPAZ-Ⅱ are then simulated and analyzed at the steady state. The calculation results agree well with the design values. The current work provides a solid foundation for space reactor design and transient analysis in the future.
文摘An anaerobic baffled reactor is a system developed in recent decades and has been used as part of the treatment of high-strength wastewater. Since the function of this system is based on its hydrodynamic features, hydrodynamics and the regime of the flow through the reactor are crucial. In this study, a prototype reactor with eight chambers, which had a total volume of 48 L, and a model reactor, whose dimensions were half of those of the prototype reactor, were used. The Froude dynamic similitude in these reactors was investigated. The results show that the curve dimensionless variances were 0.089 and 0.096 for the prototype and model reactors, respectively, the short-circuiting indices were 0.483 and 0.489 for the prototype and model reactors, respectively, the effective volume and short-circuiting index measurement errors were both 1%, the hydraulic efficiency error was 2%, and the Peclet and dispersion number errors were both 7%. Most of the compared indices were close to one another in value. Therefore, the model reactor can be used based on the Froude dynamic similitude to determine hydrodynamic charac-teristics of a baffled reactor at a full scale.
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No.2002AA601310).
文摘Periodic anaerobic baffled reactor （PABR） is a novel reactor based on the design concept of anaerobic baffled reactor （ABR）. Residence time distribution （RTD） studies on both clean and working reactors at the same hydraulic residence time （HRT） of 2 d were carded out to investigate the dead spaces and mixing patterns in PABRs at different organic loading rates （OLRs） in various switching manners and frequencies. The results showed that the fraction of dead space in PABR was similar to that in ABR, which was low in comparison with other reactor designs. Dead space may be divided into two categories, hydraulic and biological. In RTD studies without biomass, the hydraulic dead space in the PABR run in an ＂every second＂ switching manner with T = 2 d was the lowest whereas that in the PABR run in a T = ∞ （ABR） switching manner was the highest. The same trend was obtained with the total dead space in RTD studies with biomass no matter what the OLR was. Biological dead space was the major contributor to dead space but affected decreasingly at higher OLR whichever switching manner the PABR run in. The flow patterns within the PABRs were intermediate between plug-flow and perfectly mixed under all the conditions tested,
文摘Anaerobic expanded bed reactor(AEBR) is mostly used for the treatment of fairly low strength wastewaters. Since the performance of AEBR largely depends on its hydraulic characteristics, residence time distribution(RTD) method is commonly used for investigation of the hydraulic characteristics of AEBR under different ascending velocity of mixed liquor. In this paper, a pilot-scale AEBR reactor is investigated for treatment of municipal sewage in which lithium chloride is used as a tracer. The results show that the AEBR could be considered as the superimposition of several constant stirred tank reactors(CSTR) and the increase of hydraulic up-flow velocity could increase the number of the CSTR and decrease the volume rate of the dead zone. The optimal up-flow velocity of the investigated AEBR was approximately 1.9 m/h in the municipal sewage treatment.
