Brayton rotating units for space reactor power systems

Gallo, Bruno M.; El‐Genk, Mohamed S.

doi:10.1016/j.enconman.2009.04.035

Cited by 66 publications

(27 citation statements)

References 14 publications

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“…The design and layout of the deployable radiator panels for the S^4-CBC space power system (El-Genk and Tournier, 2006a;El-Genk, 2008b;Gallo and El-Genk, 2009) are identical to those described earlier (Fig. 19).…”

Section: Design Of Water Heat Pipes and Radiator Panelsmentioning

confidence: 93%

“…The reactor core is divided into three hydraulically separate, but thermally and neutronically coupled sectors. Each reactor sector has a separate recuperated Closed Brayton Cycle (CBC) loop, with a turbo-machine unit for energy conversion (Gallo and El-Genk, 2009;El-Genk et al, 2010). Figure 29 presents a line diagram of one CBC loop in this power system.…”

Section: S^4-cbc Space Reactor Power Systemmentioning

confidence: 99%

“…A number of space reactor power system concepts have been developed or proposed with liquidmetal heat pipes for the passive and redundant removal and transport of the fission power generated in the reactor to the energy conversion subsystem (Angelo and Buden, 1985;El-Genk, 1994 and2008b;Ranken, 1982 andDeterman and Hagelston, 1992;, Poston et al, 2002;Ring et al, 2003; These heat pipes have also been considered for transporting waste heat from the energy conversion subsystems, and redundant and enhanced performance of heat rejection radiators. Energy conversion options considered for uses in space reactor power systems include Free-Piston Stirling Engine, FPSE (e.g., Angelo and Buden, 1985;Moriarty and Determan, 1989;Schreiber, 2001;Thieme et al, 2002 and2004;Schmitz et al, 1994 and2005), Thermoelectric (e.g., Ranken, 1982;Moriarty and Determan, 1989;Josloff et al, 1994;Marriott and Fujita, 1994;Caillat et al, 2000;Saber, 2003 and2005;Tournier, 2006b, El-Genk, 2008), Closed Brayton Cycle (CBC) with rotating turbo-machines (e.g., Harty and Mason, 1993;Shepard et al, 1994;Barrett and Reid, 2004;Barrett and Johnson, 2005;Gallo and El-Genk, 2009;El-Genk et al 2010;El-Genk, 1994 and2008), Potassium Rankine cycle (Angelo and Buden, 1985;Yoder and Graves, 1985;Bevard and Yoder, 2003), Thermionic (e.g., El-Genk and Paramonov, 1999;Ranken, 1990;…”

Section: Introductionmentioning

confidence: 99%

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Uses of Liquid-Metal and Water Heat Pipes in Space Reactor Power Systems

El‐Genk¹,

Tournier²

2011

Frontiers in Heat Pipes

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Water and liquid-metal heat pipes are considered for redundant and passive cooling of nuclear reactors and redundant operation of light-weight heat rejection radiators of space reactor power systems. The systems operate continuously for many years independent of the Sun, are enabling of deep space exploration and could provide 10's of kilowatts of electrical power for lunar and Martian outposts. Space reactors typically operate at 900 K -1400 K could be cooled using liquid-metal heat pipes with either sodium (900 -1100 K) or lithium (1100 K-1400 K) working fluids. The heat rejection temperatures dictate the working fluid of the radiator heat pipes; potassium for 600 -800 K, rubidium for 500 -700 K, and water for < 500 K. These working fluids would be frozen prior to starting up the power systems in orbit or at destination. The startup of water and liquid-metal heat pipes from a frozen state is complex, involving a number of non-linear mass and heat transport processes that require implementing appropriate procedures, depending on the type of working fluid. This paper reviews operation and design constraints pertinent to the uses of water and liquidmetal heat pipes in space reactor systems, and the modeling capabilities of the startup from a frozen state. In addition to models validation, results of design optimization of liquid-metal and water heat pipes in a number of space reactor power systems are presented and discussed.

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Section: Design Of Water Heat Pipes and Radiator Panelsmentioning

confidence: 93%

Section: S^4-cbc Space Reactor Power Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Uses of Liquid-Metal and Water Heat Pipes in Space Reactor Power Systems

El‐Genk¹,

Tournier²

2011

Frontiers in Heat Pipes

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“…Thus, the electrical power, provided by the S^4-CBC power system at steady-state, full-power operation ( Figs. 1 and 4) is 130:8 kW e at a thermal efficiency of 27:8% [26].…”

mentioning

confidence: 99%

“…The UNM-BRU-1 unit employs a permanent magnet alternator (PMA) with an efficiency of 95%. It has been optimized for operating at peak thermal efficiency and electrical power of 28.5% and 44:7 kW e , respectively, when operating at turbine and compressor inlet temperatures of 1149 K and 400 K, respectively, shaft rotation speed of 45 krpm, and input thermal power to the turbine Q sec 157 kW th [26]. The corresponding reactor thermal power is 471 kW th , divided equally among the three core sectors [8][9][10].…”

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confidence: 99%

Dynamic Simulation of a Space Reactor System with Closed Brayton Cycle Loops

El‐Genk

Tournier

Gallo

2010

Journal of Propulsion and Power

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A dynamic simulation model for space reactor power systems with multiple closed Brayton cycle loops for energy conversion is developed and demonstrated for a startup transient. The simulated power system employs a submersion-subcritical safe space S^4 reactor with a negative temperature reactivity feedback and has no singlepoint failures in reactor cooling and energy conversion. The S^4 reactor core is divided into three hydraulically independent sectors, and each sector has a separate closed Brayton cycle loop that is thermal-hydraulically coupled to a circulating liquid NaK-78 secondary loop with two water heat pipe heat rejection radiator panels. Each closed Brayton cycle loop has a Brayton rotating unit designed and optimized for high thermal efficiency and low specific mass (1:16 kg=kW e ). The reactor coolant and the closed Brayton cycle working fluid is a He-Xe binary gas mixture with a molecular weight of 40 g=mol. Results are presented for a startup transient of the S^4 closed Brayton cycle power system to full-power operation at a reactor thermal power 471 kW th , a Brayton rotating unit shaft speed of 45 krpm, and turbine and compressor inlet temperatures of 1149 and 400 K, respectively. At these conditions, the nominal electrical power and thermal efficiency of the power system are 130:8 kW e and 27.8%. NomenclatureC = compressor m = mass flow rate, kg=s m = normalized mass flow rate, kg=s, m m P ref =P o;in T o;in =T ref p P = pressure, Pa; electrical power, kW e P ref = reference pressure, 0.4 MPa T = temperature, K; turbine T ref = reference temperature, 400 K x = bleed fraction of working fluid at exit of Brayton rotating unit compressor = thermal or polytropic efficiency, % = pressure ratio ! = Brayton rotating unit shaft rotation speed, rad=s ! = normalized shaft rotation speed, rad=s, ! ! T ref =T o;in p Subscripts C = compressor e = electric G = generator in = turbine or compressor inlet o = stagnation or total P = polytropic Rx = reactor Sec = reactor sector, or BRU turbine inlet sys = power system th = thermal T = turbine

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Thermal‐hydraulic analysis of an open‐grid megawatt gas‐cooled space nuclear reactor core

et al. 2020

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Summary The development of deep space exploration requires space nuclear reactor with higher power and better endurance. In order to meet the increasing high power requirements for space applications, an Open‐grid MEgawatt Gas‐cooled spAce nuclear reactor (OMEGA) is proposed in the paper, which is featured with low specific mass and high energy conversion coefficients. A set of models, including neutron kinetics model, reactivity feedback model and heat transfer model are established. Besides, the space nuclear system analysis code (System Analysis code of MEgawatt gas‐cooled space Reactor [SAMER]) is developed by finite volume method and staggered grid technique for the preliminary safety analysis of the OMEGA conceptual design. Furthermore, the calculation results provided by the SAMER code agree well with the computational fluid dynamics simulation, validating the reliability of the code. Moreover, the transient thermal‐hydraulic responses of the OMEGA under the unprotected reactivity insertion accident (URIA) and the unprotected loss of partial coolant flow accident (LOFA) are obtained and analyzed. The maximum fuel temperature after the URIA has a margin of 262 K from the fuel temperature limit value. The total power after the LOFA is about 68.7% of the rated power, meanwhile, the fuel radial temperature distribution tends to be more uniform with the fuel average temperature unchanged. It can be found that the OMEGA design shows satisfactory safety characteristic and reliability under the URIA and the LOFA scenarios. This paper is the stage summary of the conceptual design work of the OMEGA, and it may provide useful reference for megawatt space nuclear system design and thermal‐hydraulic analysis.

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Brayton rotating units for space reactor power systems

Cited by 66 publications

References 14 publications

Uses of Liquid-Metal and Water Heat Pipes in Space Reactor Power Systems

Uses of Liquid-Metal and Water Heat Pipes in Space Reactor Power Systems

Dynamic Simulation of a Space Reactor System with Closed Brayton Cycle Loops

Thermal‐hydraulic analysis of an open‐grid megawatt gas‐cooled space nuclear reactor core

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