Progress in the development of flame-heated thermionic power sources

Martini, W. R.; McKisson, R.L.

doi:10.1016/0365-1789(63)90082-1

Cited by 2 publications

(1 citation statement)

References 2 publications

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“…For instance, an analysis may reveal the need for low-power cooling systems that can efficiently remove heat from the collector (e.g., liquid cooling, [158] heat pipes, [82,194,195] or radiation [196] ) or for efficient burner designs that recuperate waste exhaust heat and deliver it to the emitter. [197][198][199] In summary, the system efficiency incorporates energy loss pathways that are external to a TEC but nevertheless important for its operation, allowing for more meaningful comparisons between energy generation architectures.…”

Section: Efficiency Metricsmentioning

confidence: 99%

Progress Toward High Power Output in Thermionic Energy Converters

Campbell

Celenza

Schmitt³

et al. 2021

Advanced Science

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Thermionic energy converters are solid‐state heat engines that have the potential to produce electricity with efficiencies of over 30% and area‐specific power densities of 100 Wcm−2. Despite this prospect, no prototypes reported in the literature have achieved true efficiencies close to this target, and many of the most recent investigations report power densities on the order of mWcm−2 or less. These discrepancies stem in part from the low‐temperature (<1300 K) test conditions used to evaluate these devices, the large vacuum gap distances (25–100 µm) employed by these devices, and material challenges related to these devices' electrodes. This review will argue that, for feasible electrode work functions available today, efficient performance requires generating output power densities of >1 Wcm−2 and employing emitter temperatures of 1300 K or higher. With this result in mind, this review provides an overview of historical and current design architectures and comments on their capacity to realize the efficiency and power potential of thermionic energy converters. Also emphasized is the importance of using standardized efficiency metrics to report thermionic energy converter performance data.

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Section: Efficiency Metricsmentioning

confidence: 99%

Progress Toward High Power Output in Thermionic Energy Converters

Campbell

Celenza

Schmitt³

et al. 2021

Advanced Science

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Unconventional methods of electricity generation

Dunn¹,

Wright

1963

Proc. Inst. Electr. Eng. UK

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SynopsisThe paper sets out the physical principles on which the magnetohydrodynamic, thermo-electric, and thermionic generators, and the fuel cell are based. Other methods of generation, including the solar cell, are also mentioned. The limitation of the conventional steam turbo-alternator for large-scale electricity generation is pointed out, and the desirability of developing higher-temperature plant to be used in conjunction with the conventional generation plant is shown. The first three methods can be used in this role. In addition, there are possible fields of application where efficiency is not of prime importance, e.g. space vehicles. List of symbolsA -constant in Richardson's equation (Section 4.3) = 1-2 x 10<>A/m 2 per deg 2 C A = m.h.d. duct area, m 2 B = magnetic flux density, Wb/m 2 C -Wiedeman-Franz number, V 2 /deg 2 C c p ••-specific heat at constant pressure, J/kg E -electric field strength, V/m Vi -ionization potential, V F -Faraday's constant G •-thermal conductance, W/m 2 per degC G =-Gibbs free energy, J/kg H = heat loss through the m.h.d. duct wall per unit area, W/m 2 H -enthalpy, j/kg / --total current, A K --E\uB -m.h.d. loading factor K -thermal conductivity, W/m 2 per degC/m ' K e == electronic component of thermal conductivity K p -photon component of thermal conductivity L -E x l{o)xu x Bz) M •-= Z(T h + T c )/2 Mo -flow Mach number M op t -optimum Mach number a -electrical conductivity, mhos/m T, T e , T, --mean times between collisions of an electron or ion, sec T£, = time of traverse of an m.h.d. duct, sec $ = work function of an electrode, V e = emitter work function, V opt = emitter work function for maximum efficiency, V (f> c = collector work function, V co = angular cyclotron frequency, rad/s co e = electron angular cyclotron frequency, rad/s to/ = ion angular cyclotron frequency, rad/s Units.-M.K.S. units are used throughout for formulae. Some constants, e.g. thermal conductivity, are quoted in C.G.S. units where this is the standard practice.

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Progress in the development of flame-heated thermionic power sources

Cited by 2 publications

References 2 publications

Progress Toward High Power Output in Thermionic Energy Converters

Progress Toward High Power Output in Thermionic Energy Converters

Unconventional methods of electricity generation

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