Operational testing and thermal modeling of a TOPAZ-II single-cell thermionic fuel element test stand

Benke, Steven M.; Venable, J. R.

doi:10.1063/1.47241

Cited by 5 publications

(6 citation statements)

References 7 publications

(4 reference statements)

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“…A thermionic electrical converter (TEC) is a type of heat-to-electricity converter [1][2][3]. Historically TECs were used for electricity generation in satellites using nuclear reactors since they are particularly well suited to high temperature (> 1300 o C) applications [4][5][6]. The lack of moving parts in these converters as well as their relatively high conversion efficiency (relative to other heat engines) at the extreme temperatures achievable with nuclear reactors makes them particularly attractive for space applications [7].…”

Section: Introductionmentioning

confidence: 99%

Impact of Coulomb Scattering on Argon Plasma Based Thermionic Converter Performance

Groenewald¹

2021

Preprint

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Particle-in-cell (PIC) simulations were performed to study the impact of Coulomb scattering on the performance of argon plasma based thermionic converters. Using a simplified model, studies from the 1970's have concluded that plasma resistance, brought on by Coulomb collisions, causes a shift in the IV-curves of thermionic converters that use an argon plasma to mitigate space charge, thereby strongly limiting their electricity generation capability. In this work the impact of Coulomb collisions in such devices were studied as a function of the relative electrical potential between the electrodes, with higher fidelity through the use of a fully kinetic approach (PIC). This revealed that earlier reports overestimated the negative impact of Coulomb collisions around the flat-band potential. The results of the simulations are also used to comment on the validity of the assumptions made in the simplified model.

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Section: Introductionmentioning

confidence: 99%

Impact of Coulomb Scattering on Argon Plasma Based Thermionic Converter Performance

Groenewald¹

2021

Preprint

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“…Apart from concentrated solar heating, thermionic converters with other sources of heat have been experimentally demonstrated. For example, TOPAZ reactor (a Russian acronym for Thermionic Experiment with Conversion in Active Zone) was developed by the former Soviet Union (USSR) [12][13][14]. In 1986 and 1987, the USSR launched two reconnaissance satellites into the lower earth orbit powered by its 6-KW TOPAZ thermionic reactor.…”

Section: Introductionmentioning

confidence: 99%

Interplay between Near-Field Radiative Coupling and Space-Charge Effects in a Microgap Thermionic Energy Converter under Fixed Heat Input

Rahman

Nojeh

2020

Phys. Rev. Applied

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We investigate the performance of a micro gap vacuum thermionic energy converter considering the loss mechanisms due to the space charge effect and interelectrode radiative heat transfer. The dependencies of the space charge effect and near-field radiative heat exchange on the interelectrode distance are derived based on established theories. The electrode temperatures are determined by solving the steady-state energy balance equations in a numerical, iterative process and considering a constant energy flux input to the emitter. The resultant behaviour of the different mechanisms of energy flow from the electrodes is studied for a wide range of interelectrode distances, which provides new insights into the device operation.The maximum efficiency of the converter is obtained by optimizing the operating voltage and interelectrode distance. Considering the interplay between space charge and near-field radiative heat transfer, an optimal range is determined for the interelectrode distance. The optimal value of the distance and the lower limit of this range are found to be significantly higher than previously reported, where constant electrode temperatures had been assumed.

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“…The TFE experiment test units were build and tested at Scientific Industrial Association (LUTCH) in the Soviet Union in the 1970s and reassembled in the United States during the TIP in the 1990s. 10 Dmitry et al give some results about Ya-21u testing by the Soviet Union and the United States in the 1990s, including Volt-Ampere characteristics and load voltage optimization 11 Although much work has been conducted on the thermoelectric characteristics of the individual TFEs, few researchers have studied thermoelectric characteristics of the thermionic space nuclear power system, and the method may not be suitable for design and analysis of a new thermionic space nuclear power reactor. V-71 is a prototype TFE for TOPAZ-II, while the Ya-21u has several modifications on cesium reservoir, etc.…”

Section: Introductionmentioning

confidence: 99%

“…9 Benke et al developed a thermal analysis network method in low power level. 10 Dmitry et al give some results about Ya-21u testing by the Soviet Union and the United States in the 1990s, including Volt-Ampere characteristics and load voltage optimization 11 Although much work has been conducted on the thermoelectric characteristics of the individual TFEs, few researchers have studied thermoelectric characteristics of the thermionic space nuclear power system, and the method may not be suitable for design and analysis of a new thermionic space nuclear power reactor. In our previous work, an improved TOPAZ-II using potassium heat pipe radiator is proposed, and the transient thermalhydraulic characteristics of the reactor are conducted.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric characteristics analysis of thermionic space nuclear power reactor

et al. 2019

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A thermoelectric analysis of space nuclear power reactor is of great importance to the space reactors development. In this paper, the reactor core model of TOPAZ-II designed by Soviet Union, including neutronics model, thermal-hydraulic model, and electrical circuit model, is established based on reasonable assumptions. A system analysis code is developed to analyze the thermoelectric characteristics of the TOPAZ-II under the condition of steady-state operation, start-up procedure, power change mode, and reactor shutdown. The code has been benchmarked with experimental data, and the maximum relative error is 16.6%. Numerical results show that for the steady state, the simulated electrical power is 5.2 kW within the design value range. For transient state, the reactor thermoelectric characteristics are mainly affected by the electrode temperature: (a) For the start-up procedure, when the emitter temperature increases above 1700 K, electrical system begins to work and reach full power in 5 minutes. (b) For power change mode, the emitter temperature decreases by 5%, while the electrical power decreases by 67%; (c) For reactor shutdown, electrical power reduces to 0 kW as the emitter temperature decreases to 1400 K in 100 seconds. This study provides valuable theoretical supports for the design and analysis of the thermionic space nuclear power reactor. KEYWORDS steady and transient analysis, thermoelectric characteristics, thermionic space nuclear power reactor Nomenclature: A, cross section area (m 2 ); C, delayed neutron precursor concentration (m −3 ); c, specific heat (J kg −1 K −1 ); D, diameter (m); e, electron charge, 1.602 × 10 −19 C; H, heat transfer coefficient (W m −2 K −1 ); I, current (A); J, current density (A/cm 2 ); k, boltzman constant, 1/11 600; N, number; P, power (W); Q, heat source (W m -3 ); r, radius (m); T, temperature (K); t, time (s); l, length (m); p, pressure (Pa); V, volume (m 3 )/voltage (V); W, mass flow rate (kg s −1 ) characteristics analysis of thermionic space nuclear power reactor. Int J Energy Res. 2020;44:855 868 .

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Operational testing and thermal modeling of a TOPAZ-II single-cell thermionic fuel element test stand

Abstract: Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completmg and reviewing the collection of information. Send

Cited by 5 publications

References 7 publications

Impact of Coulomb Scattering on Argon Plasma Based Thermionic Converter Performance

Impact of Coulomb Scattering on Argon Plasma Based Thermionic Converter Performance

Interplay between Near-Field Radiative Coupling and Space-Charge Effects in a Microgap Thermionic Energy Converter under Fixed Heat Input

Thermoelectric characteristics analysis of thermionic space nuclear power reactor

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