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US-12626832-B2 - Energy converter system and method of operation

US12626832B2US 12626832 B2US12626832 B2US 12626832B2US-12626832-B2

Abstract

An energy converter system, preferably including one or more thermionic energy converters (TECs), and optionally including an electrical power converter. A TEC, preferably including a collector body, an emitter body, and a seal. A method of operation for an energy converter system, preferably including providing a heat source; converting thermal energy to electrical energy; and/or providing one or more electrical energy outputs.

Inventors

  • Jared William Schwede
  • Felix T. Schmitt
  • Lucas Heinrich Hess

Assignees

  • Spark Thermionics, Inc.

Dates

Publication Date
20260512
Application Date
20250523

Claims (20)

  1. 1 . A system comprising a thermionic energy converter (TEC), the TEC defining a chamber comprising: a gap region defining a gap; a reservoir; and a conduit, wherein the reservoir is fluidly coupled to the gap region via the conduit; wherein the TEC comprises: an emitter body defining a cavity, the emitter body comprising: a first electrical output; an emitter surface bounding the cavity and bounding the gap region; and an emitter sidewall electrically and mechanically connected to the emitter surface, the emitter sidewall bounding the cavity, wherein the emitter sidewall electrically couples the emitter surface to the first electrical output; a collector body comprising a second electrical output and a collector surface arranged within the cavity, wherein: the collector surface opposes the emitter surface across the gap, wherein the gap is defined within the cavity between the collector surface and the emitter surface; and the collector body defines the reservoir and the conduit; a seal that mechanically connects the emitter body to the collector body, wherein the seal does not electrically connect the emitter body to the collector body; a capture material arranged within the reservoir, the capture material comprising porous alumina; and a getter arranged within the chamber.
  2. 2 . The system of claim 1 , wherein: the chamber is hermetically sealed; the TEC further comprises cesium adsorbed to the capture material; and the getter pumps at least one undesired species from the chamber.
  3. 3 . The system of claim 2 , wherein the at least one undesired species comprises at least one of: water, hydrogen, hydroxide, or molecular nitrogen.
  4. 4 . The system of claim 2 , wherein: the collector surface defines a first temperature substantially greater than an ambient temperature; the emitter surface defines a second temperature substantially greater than the first temperature; the capture material defines a third temperature similar to the first temperature; the capture material releases cesium vapor and the at least one undesired species into the chamber, wherein a portion of the cesium vapor reaches the emitter surface; and in response to the portion of the cesium vapor reaching the emitter surface and the emitter surface defining the second temperature, the emitter surface thermionically emits electrons across the gap region to the collector surface.
  5. 5 . The system of claim 1 , wherein the porous alumina defines a Brunauer-Emmett-Teller ratio greater than 30 m 2 /g.
  6. 6 . The system of claim 1 , wherein the porous alumina defines a Brunauer-Emmett-Teller ratio greater than 100 m 2 /g.
  7. 7 . The system of claim 1 , wherein the getter comprises titanium and zirconium.
  8. 8 . The system of claim 7 , wherein the getter is a non-evaporable getter.
  9. 9 . The system of claim 8 , wherein the TEC further comprises a low-temperature getter arranged within the chamber, the low-temperature getter comprising titanium and zirconium.
  10. 10 . The system of claim 1 , wherein: the getter comprises zirconium; and the getter is arranged within the reservoir.
  11. 11 . The system of claim 1 , wherein: the getter comprises zirconium; and the getter is arranged within less than 20 mm of the capture material.
  12. 12 . The system of claim 11 , wherein the capture material does not comprise graphite.
  13. 13 . The system of claim 1 , wherein the porous alumina comprises activated alumina.
  14. 14 . The system of claim 1 , wherein the capture material is thermally connected to the collector surface via the collector body.
  15. 15 . A method for thermionic energy conversion, comprising: at an emitter body of a thermionic energy converter (TEC), receiving a heat input; in response to receiving the heat input, at the TEC, transferring a first portion of heat from the emitter body to a collector body of the TEC, wherein the first portion of heat increases a reservoir temperature of a reservoir within the collector body, wherein the reservoir comprises porous alumina and cesium adsorbed to the porous alumina; in response to increasing the reservoir temperature, at the reservoir, desorbing cesium from the porous alumina, wherein a portion of the desorbed cesium migrates to an emitter surface of the emitter body via a chamber comprising the reservoir; at a getter arranged within the chamber, pumping at least one undesired species from the chamber; in response to receiving the heat input and in response to the cesium migrating to the emitter surface, at the emitter surface, thermionically emitting electrons into the chamber; and at a collector surface of the collector body, receiving the thermionically emitted electrons.
  16. 16 . The method of claim 15 , wherein, while thermionically emitting electrons at the emitter surface: the emitter surface defines an emitter temperature; the collector surface defines a collector temperature; a difference between the emitter temperature and the collector temperature is at least 200° C.; and a difference between the reservoir temperature and the collector temperature is less than 100° C.
  17. 17 . The method of claim 16 , wherein the difference between the reservoir temperature and the collector temperature is less than 40° C.
  18. 18 . The method of claim 15 , further comprising, in response to increasing the reservoir temperature, concurrent with desorbing cesium from the porous alumina, desorbing the at least one undesired species from the porous alumina, wherein the at least one undesired species comprises at least one of: water, hydrogen, hydroxide, or molecular nitrogen.
  19. 19 . The method of claim 18 , wherein: the getter comprises zirconium; and the getter is arranged within less than 20 mm of the porous alumina.
  20. 20 . The method of claim 15 , wherein the porous alumina comprises activated alumina defining a Brunauer-Emmett-Teller ratio greater than 50 m 2 /g.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63/651,300 filed 23 May 2024, which is herein incorporated in its entirety by this reference. STATEMENT OF GOVERNMENT SUPPORT This invention was made with government support under Contract No. 80NSSC22CA069 awarded by the National Aeronautics and Space Administration. The government has certain rights in the invention. TECHNICAL FIELD This invention relates generally to the energy converter field, and more specifically to a new and useful energy converter system and method of operation. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic representation of an embodiment of an energy converter system. FIG. 2 is a schematic representation of an embodiment of a method of operation for an energy converter system. FIG. 3 is a schematic representation of an embodiment of a TEC of the energy converter system. FIGS. 4A-4B are an elevation view and a cross-sectional elevation view, respectively, of an example of the TEC. FIG. 4C is a cross-sectional elevation view of a specific example of the TEC. FIGS. 5A-5B are an isometric view and a cross-sectional elevation view, respectively, of a specific example of a collector body of the TEC. FIGS. 6A-6B are cross-sectional elevation views of an example of an emitter body and a collector body, respectively, of the TEC. DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of the preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use this invention. 1. Overview. An energy converter system preferably includes one or more thermionic energy converters (TECs) 100, and can optionally include an electrical power converter 200 (e.g., as shown in FIG. 1). The TECs preferably function to convert thermal energy to electrical energy. The electrical power converter 200 can function to operate the TECs at or near their optimal power point and/or convert generated electrical power to a desired (e.g., constant voltage) output. However, the system can additionally or alternatively include any other suitable elements and/or be configured in any other suitable manner. A method of operation for an energy converter system (e.g., as shown in FIG. 2) preferably includes providing a heat source (e.g., to an emitter of one or more TECs), such as a waste heat source (e.g., hot airstream surrounding a vehicle, such as heated due to vehicle velocity, combustion, etc.; heat around and/or within a vehicle, such as heat around and/or within a vehicle engine and/or heat generated by the vehicle engine; heat generated by any suitable equipment, such as heat around and/or within the equipment; heat of combustion; etc.) but additionally or alternatively a dedicated heat source (e.g., combustion heat source such as a burner configured to heat the TEC(s), preferably a high-temperature recuperative burner but additionally or alternatively any other suitable combustion heat source); converting thermal energy to electrical energy (e.g., at the TECs, via thermionic emission); and/or providing one or more electrical energy outputs. The method can optionally include converting the electrical energy (e.g., at one or more electrical power converters), such as converting electrical energy provided by one or more TECs to a desired output characteristic (e.g., constant or substantially constant output voltage). However, the method can additionally or alternatively include any other suitable elements performed in any suitable manner. The method of operation is preferably performed using the energy converter system described herein, but can additionally or alternatively be performed using any other suitable system(s). The energy converter system is preferably operable and/or configured to perform the method of operation described herein, but can additionally or alternatively have any other suitable functionality. 2. System. 2.1 Thermionic Energy Converter. Each thermionic energy converter (TEC) 100 preferably functions to receive heat and convert the heat to an electrical power output. Each TEC of the system is preferably a hot shell TEC including a heated emitter body surrounding (e.g., partially surrounding) a collector body. However, the system can additionally or alternatively include one or more button style TECs, inverted design TECs (e.g., as described in U.S. patent application Ser. No. 17/866,381, filed 15 Jul. 2022 and titled “SYSTEM AND METHOD FOR THERMIONIC ENERGY GENERATION”, which is herein incorporated in its entirety by this reference, such as described therein regarding the TEC), and/or TECs having any other suitable designs. The TECs can include plasma-based TECs (e.g., wherein during operation, the vacuum gap between the TEC emitter and collector has an ignited plasma, such as a cesium plasma, which can, in some examples, function to reduce space charge effect