Modeling of Remote Condensing AMTEC Cells

Ivanenok, Joseph F.; Sievers, R.K.; Schultz, William W.

doi:10.1063/1.2950170

Cited by 13 publications

(3 citation statements)

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“…These aspects are interrelated and may be dealt with, respectively, by four submodels: flow model, thermal model, electrochemical model, and electric circuit model. Only a few investigators have attempted to establish a flow model to calculate the vapor pressure losses, owing to the complexity of the cell geometry and the fact that the vapor flow is in the transition or the free-molecular regime [23][24][25][26]. Schock et al [27,28] and Hendricks et al [29] developed complex thermal, electrical, and vapor flow models of vapor anode multi-tube AMTEC cells.…”

Section: Analytical Model Of Amtecsmentioning

confidence: 99%

A review on advances in alkali metal thermal to electric converters (AMTECs)

Xiao

Cao

2009

Int. J. Energy Res.

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SUMMARYThe alkali metal thermal to electric converter (AMTEC) is one of the most promising technologies for direct conversion of thermal energy to electricity and has been receiving attention in the field of energy conversion and utilization in the past several decades. This paper aims to present a comprehensive review of the state of the art in the research and development of the AMTEC, including its working principles and types, historical development and applications, analytical models, working fluids, electrode materials, as well as the performance and efficiency improvement. The current two major problems encountered by the AMTEC, the time-dependent power degradation and relatively low efficiency compared to its theoretical value, are discussed in depth. In addition, a brief comparison of the AMTEC with other direct thermal to electric converters (DTECs), such as the thermoelectrics converter (TEC), thermionics converter, and thermophotovoltaics converter, is given, and combinations of different DTECs to further improve DTECs' power generation and overall conversion efficiency are demonstrated. Future research and development directions and the issues that need to be further investigated are also suggested. It is believed that this comprehensive review will be beneficial to the design, simulation, analysis, performance assessment, and applications of various types of AMTECs.

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Section: Analytical Model Of Amtecsmentioning

confidence: 99%

A review on advances in alkali metal thermal to electric converters (AMTECs)

Xiao

Cao

2009

Int. J. Energy Res.

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“…As part of this program, a detailed model of vaporanode multitube cells is being developed. Ivanenok and Sievers (1996) have developed a vapor-anode multitube AMTEC cell model by coupling a one-node electrical model with a slipflow vapor pressure loss model (Ivanenok et al 1994), and a 20-node thermal model of the cell. The thermal model accounted for both radiation and conduction in the cell.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of a multitube vapor-anode AMTEC cell

Tournier

El‐Genk²,

Huang³

et al. 1997

IECEC-97 Proceedings of the Thirty-Second Intersociety Energy Conversion Engineering Conference (Cat. No.97CH6203)

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A detailed AMTEC Performance and Evaluation Analysis Model (APEAM) was developed to predict the performance of next-generation Pluto Express vapor-anode multitube cells. APEAM incorporates an axial electrochemical model, which accounts for the effects of non-uniform axial temperature and vapor pressure profiles along the BASE tubes; a detailed vapor pressure loss model, which includes free-molecular, transition, and continuum flow regimes; and a comprehensive radiationiconduction model, which incorporates the effects of circumferential thermal shields above the BASE tubes and conduction studs between the hot end of the cell and the tubes support plate. Model results compared well with measured electrical power and experimental I-V characteristics of the PX-2C cell, recently tested at Phillips Laboratory. The cell peak electric power of 4.4 We occurred at an external load resistance of 3.0 R. At higher load resistance (or lower load demand), the PX-2C cell was load-following. Results also showed that the vapor flow on the low-pressure side of PX-2C was in the transition regime. The evaporator wick provided the sodium flow rate (8 g/hour) necessary to operate the cell at an evaporator temperature of about 950 K. The model predicted that using a molybdenum thermal shield on the inside of the cell wall, near the condenser, would increase the cell electric power and conversion efficiency by -23%.

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“…Ivanenok et al 4 developed a vapor pressure loss model for a single-tube AMTEC, with an internal heat shield (disk) and a remote coaxial condenser tube. They assumed a continuum vapor flow having a parabolic radial velocity profile and corrected the laminar friction coefficient for a slip flow condition.…”

mentioning

confidence: 99%

Sodium Vapor Pressure Losses in a Multitube, Alkali-Metal Thermal-to-Electric Converter

Tournier

El‐Genk

1999

Journal of Thermophysics and Heat Transfer

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A model was developed to calculate the vapor pressure losses and characterize the vapor flow regimes on the cathode side of a multitube, vapor-anode, alkali-metal thermal-to-electric converter (AMTEC) cell, with internal chevron's radiation shields. The dusty gas model was used to predict the vapor flow over a wide range of pressures, including the free-molecular, transition, and continuum flow regimes. Results showed that the vapor flow on the cathode side of a multitube AMTEC cell is typically in the transition regime, and that the pressure loss in the chevron's shield accounts for about 50% of the total pressure losses. An analysis is also performed to optimize the conical chevron's geometry for minimum pressure loss. Nomenclature A= surface area, m 2 a cc = accommodation coefficient, Eqs. (1) and (25), 1 b = perpendicular distance between chevrons, m D = flow diffusion coefficient, m 2 /s D a = diameter of centerline liquid-return artery, m, 3.18 mm D B = BASE tubes outer diameter, m, 6.35 mm D e = equivalent hydraulic diameter, m D w = inner diameter of AMTEC cell wall, m, 33.2 mm d = separation distance between chevrons, m F = Faraday's constant, 96,485 C/mol / = laminar friction coefficient G -dimensionless geometric factor for pressure loss, Eq. (5) / = total cell electrical current, A J r = electrode current density, A/m 2 Kn -Knudsen number of sodium vapor L = effective flow path through chevrons, m L B = distance between bottom of electrode and top of BASE tube, m L c = distance between BASE tubes top and chevrons, m L s = height of chevron's shield, m L T = distance between chevrons and condenser, m M = molecular weight of sodium, kg/mol, 23 gm/mol Ma = vapor Mach number, w"A/ypP Wp 0re = vapor mass flux in electrode pores, kg/m 2 s m z -vapor axial mass flow rate, kg/s m" = vapor axial mass flux, kg/m 2 s N = number of conical chevrons N B = number of (seried-connected) BASE tubes, 7 P = sodium vapor pressure, Pa Re = vapor Reynolds number, D e m"/jji R g = perfect gas constant, 8.314 J/mol K R p -average hydraulic radius of electrode pores, m, 10 jam T = temperature, K t E = thickness of cathode electrode, m, 5 ^m z = axial coordinate, m a = chevrons packing factor, Fig. 3 a 2= coefficient for advection of axial momentum y = specific heat ratio of sodium vapor, 5/3 AP = pressure loss through conical chevron's shield, Pa APcd = pressure loss due to condensation of sodium, Pa AP £ = pressure loss through cathode electrode, Pa APevap = pressure loss as a result of evaporation of sodium at BASE surface, Pa e £ = volume porosity of cathode electrode, 0.9 £ = correction factor for laminar flow in annulus 0 = angle of conical chevrons, Fig. 3 IJL = dynamic viscosity of sodium vapor, kg/m s £ = resistance coefficient for sudden expansion, Eqs. (13) and (14) p = vapor density (kg/m 3 ), PMI(R S T) 9 = compressible factor, Eq. (26) X = flow conductance of chevron's shield, m 2 /s Subscripts B = beta"-alumina solid electrolyte (BASE) c = cathode electrode/BASE interface cd = condenser ev = evaporator E = catho...

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Modeling of Remote Condensing AMTEC Cells

Cited by 13 publications

References 3 publications

A review on advances in alkali metal thermal to electric converters (AMTECs)

A review on advances in alkali metal thermal to electric converters (AMTECs)

Performance analysis of a multitube vapor-anode AMTEC cell

Sodium Vapor Pressure Losses in a Multitube, Alkali-Metal Thermal-to-Electric Converter

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