Thermal pump with heat-exchanging displacer

Abstract

A thermal pump may include a cylinder having a hot end and a cold end, with heating elements at the hot end and cooling elements at the cold end. A piston assembly movable within the cylinder may include a regenerator, a hot displacer, and a cold displacer. The hot displacer can include a thermally-conductive segment shaped to surround the heating elements when in a cooling position, and a thermally-insulating segment between the conductive segment and the regenerator. The cold displacer can include a thermally-conductive segment shaped to surround the cooling elements when in a heating position, and a thermally-insulating segment between the conductive segment and the regenerator.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Serial Number 63 / 750,773, filed January 29, 2025, naming Anatoly Shchemelinin as inventor, which is incorporated herein by reference in the entirety.TECHNICAL FIELD

[0002] The present disclosure relates to thermal pumps, and more particularly to a thermal pump with a displacer design that incorporates the displacer as an active heat exchange component.BACKGROUND

[0003] Thermal pumps operating on thermodynamic cycles typically include a cylinder with a hot end and a cold end, along with a piston that moves gas between the hot and cold regions to create pressure differentials. The piston conventionally includes displacers at each end and a regenerator in the middle. Traditional displacer designs have focused on using materials with low thermal conductivity and low heat capacity to minimize heat transfer through the displacer itself, with the goal of thermally isolating the hot and cold ends from each other. While this approach has been suitable for certain applications, particularly cryogenic systems and high-pressure pumping, it presents challenges when thermal pumps are operated at elevated temperatures or when high gas flow rates are desired. Materials that provide adequate thermal insulation may not withstand high operating temperatures, may be susceptible to thermal shock, or may introduce cleanliness concerns in applications where contamination is problematic.

[0004] There is therefore a need to develop systems and methods addressing the above deficiencies.SUMMARY

[0005] In embodiments, a thermal pump may include a cylinder having a hot end and a cold end. One or more heating elements may be positioned at the hot end. One or more cooling elements may be positioned at the cold end. A piston assembly may be movable within the cylinder. The piston assembly may include a regenerator. The piston assembly may include a hot displacer. The hot displacer may include a thermally-conductive hot displacer segment shaped to surround the one or more heating elements when the piston assembly is in a cooling position. The hot displacer may further include a thermally-insulating hot segment between the thermally-conductive hot displacer segment and the regenerator. The piston assembly may include a cold displacer. The cold displacer may include a thermally-conductive cold displacer segment shaped to surround the one or more cooling elements when the piston assembly is in a heating position. The cold displacer may further include a thermally-insulating cold segment between the thermally-conductive cold displacer segment and the regenerator. In the cooling position, the one or more cooling elements and the thermally-conductive cold displacer segment may cool gas near the cold end of the cylinder, and the one or more heating elements may heat the thermally-conductive hot displacer segment. In the heating position, the one or more heating elements and the thermally-conductive hot displacer segment may heat gas near the hot end of the cylinder, and the one or more cooling elements may cool the thermally-conductive cold displacer segment.

[0006] In embodiments, at least one of the thermally-conductive hot displacer segment, the thermally-conductive cold displacer segment, or the regenerator may include at least one of aluminum, an aluminum alloy, copper, or a copper alloy.

[0007] In embodiments, at least one of the thermally-insulating hot displacer segment or the thermally-insulating cold displacer segment may include at least one of a glass or a ceramic.

[0008] In embodiments, at least one of the thermally-insulating hot displacer segment or the thermally-insulating cold displacer segment may include stacked metal plates with gaps therebetween.

[0009] In embodiments, at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment may be formed as different components.

[0010] In embodiments, at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment may be formed as a monolithic component providing thermal insulation in at least an axial direction between the hot end and the cold end of the cylinder.

[0011] In embodiments, the monolithic component may include at least one of graphite or carbon fiber.

[0012] In embodiments, the regenerator, the thermally-conductive hot displacer segment and the thermally-insulating hot displacer segment may be divided into multiple components associated with different ones of the one or more heating elements.

[0013] In embodiments, the regenerator, the thermally-conductive cold displacer segment and the thermally-insulating cold displacer segment may be divided into multiple components associated with different ones of the one or more cooling elements.

[0014] In embodiments, the thermal pump may further include at least one of a coating or surface structures on at least one of the thermally-conductive hot displacer segment or the thermally-conductive cold displacer segment to promote radiative heat transfer.

[0015] In embodiments, the coating may include a black coating.

[0016] In embodiments, the thermally-conductive hot displacer segment may include cavities shaped to complement the one or more heating elements, and the thermally-conductive cold displacer segment may include cavities shaped to complement the one or more cooling elements.

[0017] In embodiments, at least one of the one or more heating elements or the one or more cooling elements may be shaped with a circular cross-section in a plane orthogonal to a longitudinal axis between the hot end and the cold end of the cylinder.

[0018] In embodiments, at least one of the one or more heating elements or the one or more cooling elements may be shaped with a non-circular cross-section in a plane orthogonal to a longitudinal axis between the hot end and the cold end of the cylinder.

[0019] In embodiments, a piston assembly for a thermal pump may include a regenerator. The piston assembly may include a hot displacer. The hot displacer may include a thermally-conductive hot displacer segment shaped to surround one or more heating elements in a hot end of a cylinder when the piston assembly is in a cooling position in the cylinder. The hot displacer may further include a thermally-insulating hot segment between the thermally-conductive hot displacer segment and the regenerator. The piston assembly may include a cold displacer. The cold displacer may include a thermally-conductive cold displacer segment shaped to surround one or more cooling elements in a cold end of the cylinder when the piston assembly is in a heating position in the cylinder. The cold displacer may further include a thermally-insulating cold segment between the thermally-conductive cold displacer segment and the regenerator. In the cooling position, the one or more cooling elements and the thermally-conductive cold displacer segment may cool gas near the cold end of the cylinder, and the one or more heating elements may heat the thermally-conductive hot displacer segment. In the heating position, the one or more heating elements and the thermally-conductive hot displacer segment may heat gas near the hot end of the cylinder, and the one or more cooling elements may cool the thermally-conductive cold displacer segment.

[0020] In embodiments, at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment may be formed as different components.

[0021] In embodiments, at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment may be formed as a monolithic component providing thermal insulation in at least an axial direction between the hot end and the cold end of the cylinder.

[0022] In embodiments, the regenerator, the thermally-conductive hot displacer segment and the thermally-insulating hot displacer segment may be divided into multiple components associated with different ones of the one or more heating elements.

[0023] In embodiments, the regenerator, the thermally-conductive cold displacer segment and the thermally-insulating cold displacer segment may be divided into multiple components associated with different ones of the one or more cooling elements.

[0024] In embodiments, the piston assembly may further include at least one of a coating or surface structures on at least one of the thermally-conductive hot displacer segment or the thermally-conductive cold displacer segment to promote radiative heat transfer.

[0025] In embodiments, a method may include placing a piston assembly within a cylinder having a hot end with one or more heating elements and a cold end with one or more cooling elements. The piston assembly may include a regenerator. The piston assembly may include a hot displacer. The hot displacer may include a thermally-conductive hot displacer segment shaped to surround the one or more heating elements when the piston assembly is in a cooling position. The hot displacer may further include a thermally-insulating hot segment between the thermally-conductive hot displacer segment and the regenerator. The piston assembly may include a cold displacer. The cold displacer may include a thermally-conductive cold displacer segment shaped to surround the one or more cooling elements when the piston assembly is in a heating position. The cold displacer may further include a thermally-insulating cold segment between the thermally-conductive cold displacer segment and the regenerator. The method may include moving the piston assembly to the cooling position. In the cooling position, the one or more cooling elements and the thermally-conductive cold displacer segment may cool gas near the cold end of the cylinder, and the one or more heating elements may heat the thermally-conductive hot displacer segment. The method may include moving the piston assembly to the heating position. In the heating position, the one or more heating elements and the thermally-conductive hot displacer segment may heat gas near the hot end of the cylinder, and the one or more cooling elements may cool the thermally-conductive cold displacer segment.

[0026] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed.  The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and together with the general description, serve to explain the principles of the invention.BRIEF DESCRIPTION OF FIGURES

[0027] The numerous advantages of the disclosure may be better understood by those skilled in the art by reference to the accompanying figures.

[0028] FIG. 1 illustrates a block diagram of a thermal pump, in accordance with one or more embodiments of the present disclosure.

[0029] FIG. 2 illustrates cross-sectional views of a conventional thermal pump shown in two operational positions, in accordance with one or more embodiments of the present disclosure.

[0030] FIG. 3 illustrates a cross-sectional view of the thermal pump of FIG. 1 with a piston assembly in a cooling position, in accordance with one or more embodiments of the present disclosure.

[0031] FIG. 4 illustrates a flowchart for a method for operating a thermal pump, in accordance with one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0032] Reference will now be made in detail to the subject matter disclosed, which is illustrated in the accompanying drawings.  The present disclosure has been particularly shown and described with respect to certain embodiments and specific features thereof.  The embodiments set forth herein are taken to be illustrative rather than limiting.  It should be readily apparent to those of ordinary skill in the art that various changes and modifications in form and detail may be made without departing from the spirit and scope of the disclosure.

[0033] Embodiments of the present disclosure are directed to systems and methods providing thermal pumps with displacer designs that incorporate the displacer as an active heat exchange component to improve flow performance and operational temperature range. In embodiments, a thermal pump includes a piston assembly with hot and cold displacers that each comprise a thermally-conductive segment and a thermally-insulating segment, where the thermally-conductive segments participate in heat exchange with the gas while the thermally-insulating segments provide thermal isolation from the regenerator.

[0034] It is contemplated herein that traditional displacer designs for thermal pumps with piston displacers utilize materials with low thermal conductivity and low heat capacity to thermally isolate the hot and cold ends of the pump in opposing cycles, which introduces significant limitations on material selection and heat exchange performance. Most materials suitable for traditional displacers are polymers, which are not suitable for high-temperature operation; while this is not a significant disadvantage for typical thermal pump applications that focus on low-temperature uses such as cryogenic systems, it presents challenges for elevated temperature operation. Alternative materials such as ceramics (e.g., MACOR) can handle high temperatures but are vulnerable to thermal shock, which is a natural occurrence during thermal pump operation. Additionally, low thermal conductivity and low heat capacity displacers typically do not participate in the heat exchange process, meaning that heating and cooling of the gas is performed directly and solely by the heat exchangers (heater and cooler), which reduces the throughput of the pump. While both of these disadvantages may not particularly significant for traditional thermal pump applications, they become critical limitations in flow-through systems that must operate at high temperatures and flow rates such as, but not limited to, plasma light source applications.

[0035] In embodiments, a thermal pump includes a cylinder having a hot end with one or more heating elements and a cold end with one or more cooling elements, along with a piston assembly movable within the cylinder. The piston assembly may include a regenerator positioned between a hot displacer and a cold displacer, each with at least two segments with different thermal properties. For example, the hot displacer may include a thermally-conductive hot displacer segment positioned adjacent to the heating elements and a thermally-insulating hot displacer segment positioned between the thermally-conductive hot displacer segment and the regenerator. Similarly, the cold displacer may include a thermally-conductive cold displacer segment positioned adjacent to the cooling elements and a thermally-insulating cold displacer segment positioned between the thermally-conductive cold displacer segment and the regenerator.

[0036] During a cooling phase in which the piston assembly is in a cooling position, the piston assembly moves toward the hot end of the cylinder, which exposes gas at the cold end of the cylinder to the cooling elements for cooling of the gas. During a heating phase in which the piston assembly is in a heating position, the piston assembly moves toward the cold end of the cylinder, which exposes gas at the hot end of the cylinder to the heating elements for cooling of the gas.

[0037] Additionally, it is contemplated herein that utilizing thermally-conductive segments in the hot and cold displacers enables additional heat exchange during opposing cycles. In particular, the heating elements may heat the thermally-conductive hot displacer segment during the cooling phase such that the thermally-conductive hot displacer segment may participate in the heating of the gas during the heating phase alongside the heating elements. Similarly, the cooling elements cool the thermally-conductive cold displacer segment during the heating phase such that the thermally-conductive cold displacer segment may participate in the cooling of the gas during the cooling phase alongside the cooling elements. Accordingly, the displacers actively participate in heat exchange with the gas, enabling both the heater and cooler to operate continuously rather than only during half of the thermal cycle. In this configuration, the functionality of the thermally-conductive segments of the displacers and the regenerator may be similar, as each stores and releases thermal energy to facilitate heat exchange with the gas during alternating phases of operation.

[0038] The thermal pump design disclosed herein may enable significant improvements compared to traditional thermal pump designs. For example, the design simplifies material requirements by allowing the use of thermally-conductive materials such as metals for the displacer segments, which leads to a more cost-effective design capable of higher operating temperatures than traditional polymer-based displacers. As another example, the design improves performance of the thermal pump in terms of both throughput (gas flow) and pressure gain. For example, in some implementations, the system may achieve approximately a two-fold increase (or even higher) in gas flow rates by utilizing the displacers as active heat exchange components that participate in heating and cooling during alternating phases of operation. Both of these improvements are critical for flow-through applications in demanding environments requiring high temperatures and flow rates such as, but not limited to, broadband plasma (BBP) light sources.

[0039] In some embodiments, the thermal pump may be a part of or integrated into a light source. For example, the thermal pump may be incorporated into a light source for thermal management, gas delivery, flow control, or pressure management. Light source systems that may utilize the thermal pump may include, but are not limited to, broadband plasma (BBP) light sources, plasma light sources, or other light sources requiring controlled gas flow at elevated temperatures.

[0040] FIG. 1 illustrates a block diagram of a thermal pump 100, in accordance with one or more embodiments of the present disclosure.

[0041] In embodiments, the thermal pump 100 includes a cylinder 102 having a hot end 106 and a cold end 110. One or more heating elements 104 may be positioned at the hot end 106 of the cylinder 102, and one or more cooling elements 108 may be positioned at the cold end 110 of the cylinder 102. The one or more heating elements 104 may operate at temperatures of approximately 300°C or higher, depending on the application requirements. A piston assembly 112 may be movable within the cylinder 102 between a cooling position and a heating position to facilitate heat exchange and gas flow within the cylinder 102. Further, the piston assembly 112 may include a regenerator 114 positioned between a hot displacer 116 and a cold displacer 122.

[0042] The hot displacer 116 may include a thermally-conductive hot displacer segment 118 and a thermally-insulating hot displacer segment 120. The thermally-conductive hot displacer segment 118 may be shaped to surround the one or more heating elements 104 when the piston assembly 112 is in the cooling position. The thermally-insulating hot displacer segment 120 may be positioned between the thermally-conductive hot displacer segment 118 and the regenerator 114 to provide thermal isolation.

[0043] Similarly, the cold displacer 122 may include a thermally-conductive cold displacer segment 124 and a thermally-insulating cold displacer segment 126. The thermally-conductive cold displacer segment 124 may be shaped to surround the one or more cooling elements 108 when the piston assembly 112 is in the heating position. The thermally-insulating cold displacer segment 126 may be positioned between the thermally-conductive cold displacer segment 124 and the regenerator 114 to provide thermal isolation.

[0044] In embodiments, the thermally-conductive hot displacer segment 118, the thermally-conductive cold displacer segment 124, and / or the regenerator 114 may include materials with high thermal conductivity and high heat capacity to enable the displacers to participate in heat exchange with the gas. It is contemplated that high thermal conductivity of these materials may facilitate rapid heat transfer between the heating elements 104 or cooling elements 108 and the respective displacer segments, while high heat capacity may facilitate the storage of thermal energy for release during subsequent phases of operation. Both volumetric heat capacity and specific heat capacity may be relevant considerations for material selection. Additionally, because the piston assembly 112 is a moving component, lightweight materials may be beneficial to reduce inertia and improve responsiveness of the piston assembly 112 during operation.

[0045] Suitable materials for the thermally-conductive components may include, but are not limited to, copper, aluminum, aluminum alloys, copper alloys, or high-conductivity ceramics. In some embodiments, silicon carbide (SiC) or SiC-based composites may be used for the thermally-conductive segments. SiC-based materials may achieve thermal conductivity values ranging from below 120 W / m·K to above 500 W / m·K depending on composition and processing, while being lightweight compared to metals such as copper. In some cases, high thermal conductivity in SiC-based composites may be achieved through impregnation with diamond particles or similar high-conductivity additives. It is contemplated that diamond may provide excellent performance due to its exceptionally high thermal conductivity (approximately 2200 W / m·K) and low density, though may not be suitable in some cases due to cost and manufacturing constraints. It is further contemplated that materials with intermediate thermal conductivity, such as stainless steel (approximately 15 W / m·K) or titanium (approximately 21 W / m·K), may be less suitable for the thermally-conductive segments, as their thermal conductivity may be too high for effective thermal insulation but too low for efficient heat transfer in heat exchange applications. However, this is not a limitation and it is contemplated that such materials may be suitable for some applications.

[0046] It is contemplated herein that the thermally-insulating hot displacer segment 120 and the thermally-insulating cold displacer segment 126 may reduce parasitic heat exchange between the hot end 106 and the cold end 110 of the cylinder 102 by thermally isolating the thermally-conductive segments from the regenerator 114.

[0047] In embodiments, the thermally-insulating hot displacer segment 120 and / or the thermally-insulating cold displacer segment 126 may include materials with low thermal conductivity to provide thermal isolation between the thermally-conductive segments and the regenerator 114. In some cases, materials with low heat capacity may also be beneficial for the thermally-insulating segments, as low heat capacity may reduce the amount of thermal energy stored in the insulating segments and thereby reduce parasitic heat transfer between the hot end 106 and the cold end 110 of the cylinder 102. Suitable materials for the thermally-insulating hot displacer segment 120 and the thermally-insulating cold displacer segment 126 may include, but are not limited to, glass, ceramics, MACOR (machinable glass-ceramic material), sapphire, Teflon, or other plastics or polymers. In some embodiments, alumina, which is a polycrystalline form of sapphire, may be used. Alumina may have thermal conductivity values as low as approximately 5 W / m·K and is both cost-effective and readily machinable. More generally, the selection of material for the thermally-insulating hot displacer segment 120 or the thermally-insulating cold displacer segment 126 may depend on the operating temperatures of the one or more heating elements104 and / or the cooling elements 108. It is contemplated herein that ceramic materials such as MACOR may generally be well-suited for (but not limited to) higher temperature applications and plastics such as Teflon being well-suited for (but not limited to) lower temperature applications or for the thermally-insulating cold displacer segment 126.

[0048] In some embodiments, the thermally-insulating hot displacer segment 120 and / or the thermally-insulating cold displacer segment 126 may include porous materials to provide both low thermal conductivity and low heat capacity. Porous materials, such as porous alumina, may reduce both thermal conduction through the material and the amount of thermal energy stored in the insulating segments. However, it is contemplated that porous materials may present challenges for cleaning, which may be a consideration in applications where contamination is problematic. Therefore, the above description should not be interpreted as a limitation on the present disclosure but merely an illustration.

[0049] In some embodiments, the thermally-insulating hot displacer segment 120 or the thermally-insulating cold displacer segment 126 may include stacked plates (e.g., metal, glass, or any suitable material) with gaps therebetween, where the gaps between the stacked plates act as thermal insulators to reduce heat transfer in an axial direction between the hot end 106 and the cold end 110 of the cylinder 102.

[0050] In some embodiments, thermal insulation between displacer segments may be achieved through mechanical structures or surface treatments. For example, surface treatments including grinding or roughening may be applied to reduce contact area between adjacent components, thereby reducing heat transfer therebetween. As an illustration, the thermally-insulating hot displacer segment 120 and / or the thermally-insulating cold displacer segment 126 may include rough or brushed surfaces to reduce mechanical contact area between adjacent plates, which may reduces thermal contact and improve insulation performance. In this configuration, even materials with moderate thermal conductivity, such as stainless steel, may provide effective thermal insulation when arranged as multiple layers with brushed or roughened contact surfaces.

[0051] In some embodiments, low thermal conductivity coatings may be applied between components to provide thermal insulation. These mechanical and surface treatment approaches may be used alone or in combination with material-based thermal insulation to achieve the desired thermal isolation between the thermally-conductive segments and the regenerator 114. Therefore, the above description should not be interpreted as a limitation on the present disclosure but merely an illustration.

[0052] As used herein, the terms "thermally-conductive" and "thermally-insulating" may describe relative properties between components of the thermal pump 100. For example, the thermally-conductive segments (e.g., the thermally-conductive hot displacer segment 118 and the thermally-conductive cold displacer segment 124) may be selected to have higher thermal conductivity than the thermally-insulating segments (e.g., the thermally-insulating hot displacer segment 120 and the thermally-insulating cold displacer segment 126). In some embodiments, thermally-conductive materials may have a thermal conductivity of at least approximately 100 W / m·K. For example, copper has a thermal conductivity of approximately 400 W / m·K, aluminum has a thermal conductivity of approximately 205 W / m·K, and SiC-based composites may range from below 120 W / m·K to above 500 W / m·K depending on composition. In some embodiments, thermally-insulating materials may have a thermal conductivity below approximately 50 W / m·K. For example, glass has a thermal conductivity of approximately 1 W / m·K, MACOR has a thermal conductivity of approximately 1.5 W / m·K, Teflon has a thermal conductivity of approximately 0.25 W / m·K, and alumina may have thermal conductivity as low as approximately 5 W / m·K. These values are provided as illustrative examples and should not be interpreted as limitations on the present disclosure.

[0053] Similarly, the terms "high heat capacity" and "low heat capacity" may describe relative properties between components of the thermal pump 100. In some embodiments, materials with high heat capacity may be beneficial for the thermally-conductive segments to facilitate storage of thermal energy for release during subsequent phases of operation. For example, copper has a specific heat capacity of approximately 385 J / kg·K and a volumetric heat capacity of approximately 3,450,000 J / m³·K, aluminum has a specific heat capacity of approximately 900 J / kg·K and a volumetric heat capacity of approximately 2,430,000 J / m³·K, and SiC has a specific heat capacity of approximately 750 J / kg·K and a volumetric heat capacity of approximately 2,408,000 J / m³·K. In some embodiments, materials with lower heat capacity may be beneficial for the thermally-insulating segments to reduce the amount of thermal energy stored in the insulating segments and thereby reduce parasitic heat transfer. These values are provided as illustrative examples and should not be interpreted as limitations on the present disclosure.

[0054] Referring now to FIGS. 2-3, cross-sectional views of one non-limiting design of the thermal pump 100 and a comparison with a conventional design is described in greater detail.

[0055] FIG. 2 illustrates cross-sectional views of a conventional thermal pump 200 shown in two operational positions, in accordance with one or more embodiments of the present disclosure. A left panel 202 depicts the conventional thermal pump 200 in a cooling position, while a right panel 204 depicts the conventional thermal pump 200 in a heating position.

[0056] Referring to FIG. 2, the conventional thermal pump 200 includes a cylinder 206 having a hot end 210 at an upper portion and a cold end 214 at a lower portion. Heating elements 208 may be positioned at the hot end 210 of the cylinder 206 and may extend downward as elongated finger-like structures. Cooling elements 212 may be positioned at the cold end 214 of the cylinder 206 and may extend upward as elongated finger-like structures. A conventional piston 216 may be movable within the cylinder 206 and may include a high-temperature displacer 218 at an upper region, a low-temperature displacer 220 at a lower region, and a regenerator 222 positioned between the high-temperature displacer 218 and the low-temperature displacer 220. Gas flow components 224 may extend from a bottom of the conventional thermal pump 200.

[0057] With continued reference to FIG. 2, the high-temperature displacer 218 and the low-temperature displacer 220 may typically be made of low thermal conductivity and low heat capacity materials that thermally isolate the heating elements 208 and the cooling elements 212 from the gas during alternating phases of operation rather than participating in heat exchange. In the left panel 202, the conventional piston 216 is in the cooling position where the high-temperature displacer 218 surrounds the heating elements 208, thermally isolating the heating elements 208 from the gas, while the cooling elements 212 are exposed to actively cool the gas near the cold end 214. In the right panel 204, the conventional piston 216 is in the heating position where the low-temperature displacer 220 surrounds the cooling elements 212, thermally isolating the cooling elements 212 from the gas, while the heating elements 208 are exposed to actively heat the gas near the hot end 210. In this conventional design, the heating elements 208 and the cooling elements 212 are each active for only approximately half of the thermal cycle, which limits the throughput of the conventional thermal pump 200.

[0058] FIG. 3 illustrates a cross-sectional view of the thermal pump 100 with the piston assembly 112 in the cooling position, in accordance with one or more embodiments of the present disclosure. Although FIG. 3 depicts only the cooling position, the thermal pump 100 is configured to operate in both the cooling position and a heating position as described herein. The heating position is not separately illustrated but involves the piston assembly 112 moving toward the cold end 110 of the cylinder 102 such that the thermally-conductive cold displacer segment 124 surrounds the cooling elements 108. In particular, FIG. 3 depicts the separation of the hot displacer 116 into a thermally-conductive hot displacer segment 118 and a thermally-insulating hot displacer segment 120 as well as the separation of the cold displacer 122 into a thermally-conductive cold displacer segment 124 and a thermally-insulating cold displacer segment 126. FIG. 3 further depicts

[0059] Further, as shown in FIG. 3, the thermally-insulating hot displacer segment 120 may be positioned farther from the heating elements 104 compared to the conventional design, which may reduce thermal stress on the thermally-insulating hot displacer segment 120 and relax material requirements for thermal stress resistance. Similarly, the thermally-insulating cold displacer segment 126 may be positioned farther from the cooling elements 108. This configuration may allow the use of ceramic-like materials for the thermally-insulating hot displacer segment 120 with improved temperature resistance while reducing vulnerability to thermal shock that may occur during thermal pump operation.

[0060] Referring now generally to FIGS. 1 and 3, the operation of the thermal pump 100 is described in greater detail, in accordance with one or more embodiments of the present disclosure.

[0061] In embodiments, the piston assembly 112 operates in two primary positions within the cylinder 102: a cooling position and a heating position. The thermal pump 100 may alternates between these two positions to facilitate heat exchange and gas flow within the cylinder 102.

[0062] In the cooling position, the piston assembly 112 moves toward the hot end 106 of the cylinder 102. In this position, the thermally-conductive hot displacer segment 118 surrounds the one or more heating elements 104, which positions the thermally-conductive hot displacer segment 118 in close proximity to or in contact with the one or more heating elements 104. In this cooling position, the one or more cooling elements 108 and the thermally-conductive cold displacer segment 124 cool gas near the cold end 110 of the cylinder 102. For example, the one or more cooling elements 108 may cool the gas through contact or proximity, while the thermally-conductive cold displacer segment 124, which was pre-cooled during a previous heating position, provides additional cooling surfaces that participate in the heat exchange process with the gas. Simultaneously, while the gas is being cooled near the cold end 110, the one or more heating elements 104 heat the thermally-conductive hot displacer segment 118. The thermally-conductive hot displacer segment 118 may thus absorb and store thermal energy from the one or more heating elements 104 during the cooling position, preparing the thermally-conductive hot displacer segment 118 to participate in heating the gas during the subsequent heating position.

[0063] In the heating position, the piston assembly 112 moves toward the cold end 110 of the cylinder 102. In this position, the thermally-conductive cold displacer segment 124 surrounds the one or more cooling elements 108, which positions the thermally-conductive cold displacer segment 124 in close proximity to or in contact with the one or more cooling elements 108. During the heating position, the one or more heating elements 104 and the thermally-conductive hot displacer segment 118 heat gas near the hot end 106 of the cylinder 102. The one or more heating elements 104 directly heat the gas through contact or proximity, while the thermally-conductive hot displacer segment 118, which was pre-heated during the previous cooling position, provides additional heating surfaces that participate in the heat exchange process with the gas. Simultaneously, while the gas is being heated near the hot end 106, the one or more cooling elements 108 cool the thermally-conductive cold displacer segment 124. The thermally-conductive cold displacer segment 124 absorbs thermal energy from the one or more cooling elements 108 during the heating position, preparing the thermally-conductive cold displacer segment 124 to participate in cooling the gas during the subsequent cooling position.

[0064] It is contemplated herein that this operational configuration enables continuous operation of both the one or more heating elements 104 and the one or more cooling elements 108 throughout the thermal cycle. In traditional thermal pump designs, the heating elements and cooling elements are active only during approximately half of the thermal cycle, as the displacers thermally isolate the heating elements during the cooling phase and thermally isolate the cooling elements during the heating phase. In contrast, the thermal pump 100 disclosed herein utilizes the thermally-conductive hot displacer segment 118 and the thermally-conductive cold displacer segment 124 as thermal energy storage components that are charged during one phase and discharged during the opposing phase. This configuration allows the one or more heating elements 104 to transfer thermal energy to the thermally-conductive hot displacer segment 118 during the cooling position while the one or more cooling elements 108 are actively cooling the gas, and allows the one or more cooling elements 108 to extract thermal energy from the thermally-conductive cold displacer segment 124 during the heating position while the one or more heating elements 104 are actively heating the gas.

[0065] Further, the participation of the thermally-conductive hot displacer segment 118 and the thermally-conductive cold displacer segment 124 in the heat exchange process may equalize gas temperatures over the entire volume of the cylinder 102 during each phase of operation. In traditional thermal pump designs, the one or more heating elements 104 and the one or more cooling elements 108 are typically located at the upper and lower portions of the gas volume, respectively, which may create temperature gradients in the vertical direction and disable convection in the gas. In the thermal pump 100 disclosed herein, the thermally-conductive hot displacer segment 118 and the thermally-conductive cold displacer segment 124 provide heating and cooling surfaces at multiple elevations within the cylinder 102, which may reduce temperature gradients and equalize gas temperatures throughout the gas volume. This equalization of gas temperatures may increase the average temperature of the hot gas during the heating position and decrease the average temperature of the cold gas during the cooling position, which may directly affect the achievable pressure gain of the thermal pump 100.

[0066] In some embodiments, the thermally-conductive hot displacer segment 118 may facilitate convection-assisted heat transfer during the heating position. When the piston assembly 112 is in the heating position, the thermally-conductive hot displacer segment 118 is positioned below the gas volume near the hot end 106 of the cylinder 102. The thermally-conductive hot displacer segment 118, having been pre-heated during the cooling position, heats the gas from below, which enables natural convection as the heated gas rises. This convection-assisted heat transfer may be more efficient than heat transfer from the one or more heating elements 104 alone, which are typically positioned at the top of the gas volume where convection is disabled.

[0067] It is to be understood that the particular layout of the thermal pump 100 in FIG. 3 is provided merely for illustration and should not be interpreted as limiting. Rather, the thermal pump 100 may have various designs and implementations.

[0068] In some embodiments, the piston assembly may be configured with the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, and / or  the thermally-insulating cold displacer segment formed as different components. In such configurations, each segment may be manufactured separately and assembled together to form the piston assembly. This multi-component configuration may allow for the selection of different materials for each segment based on the specific thermal and mechanical requirements of that segment. For example, the thermally-conductive hot displacer segment may be formed from aluminum or copper, the thermally-insulating hot displacer segment may be formed from ceramic, and the regenerator may be formed from a mesh material with high heat capacity and high thermal conductivity. The use of different components may simplify manufacturing and allow for replacement of individual segments without replacing the entire piston assembly.

[0069] In some embodiments, the regenerator, the thermally-conductive hot displacer segment, and / or the thermally-insulating hot displacer segment may be divided into multiple components associated with different ones of the one or more heating elements. For example, where the thermal pump includes multiple heating elements arranged in a pattern at the hot end of the cylinder, the hot displacer may comprise multiple thermally-conductive hot displacer segment components, each associated with and shaped to surround a respective one of the multiple heating elements. Similarly, the thermally-insulating hot displacer segment and the regenerator may be divided into corresponding multiple components. This configuration may allow for independent thermal management of each heating element and may accommodate heating element arrangements with varying spacing or configurations.

[0070] As another example, the regenerator may be divided into multiple regenerator sections separated by thermal insulation layers. The thermal insulation layers between the multiple regenerator sections may reduce axial heat transfer through the regenerator, thereby improving the thermal isolation between the hot end and the cold end of the cylinder. In such configurations, the regenerator sections other than a center regenerator section may be considered as part of the displacer functionality, as each regenerator section stores and releases thermal energy during alternating phases of operation. The thermal insulation layers between the regenerator sections may include materials similar to those used for the thermally-insulating hot displacer segment or the thermally-insulating cold displacer segment, including, but not limited to, glass, ceramics, or low thermal conductivity coatings.

[0071] In some embodiments, at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment may be formed as a single component (and in some cases a single monolithic component) providing thermal insulation in at least an axial direction between the hot end and the cold end of the cylinder. For example, the piston assembly 112 provided as a monolithic component may be formed from materials that exhibit anisotropic thermal conductivity, where thermal conductivity in one direction differs from thermal conductivity in another direction. Suitable materials for the monolithic component may include, but are not limited to, graphite or carbon fiber. Graphite, for example, may exhibit high thermal conductivity in a plane perpendicular to the axial direction while exhibiting low thermal conductivity in the axial direction, thereby providing thermal insulation between the hot end and the cold end of the cylinder while allowing heat transfer in radial directions. Carbon fiber composite materials may similarly provide directional thermal conductivity properties based on the orientation of the carbon fibers within the composite. In such configurations, the piston assembly may be configured as a single displacer with distributed thermal properties, eliminating the distinct separation between displacer and regenerator functionalities. For example, the thermal properties of the piston assembly may vary continuously or in a stepwise manner along the axial direction between the hot end and the cold end of the cylinder. As an illustration, the piston assembly may have high thermal conductivity and high heat capacity near the hot end and the cold end, with lower thermal conductivity in intermediate regions to provide thermal isolation.

[0072] In some embodiments, the thermal pump 100 or the piston assembly 112 may include various techniques for enhancing heat transfer to or from the thermally-conductive hot displacer segment 118 or the thermally-conductive cold displacer segment 124. These heat transfer enhancement techniques may include, but are not limited to, modifications to the shape of the heating elements 104, cooling elements 108, or displacer segments, coatings or surface structures that promote radiative heat transfer, and active heating or cooling elements integrated within the displacer segments.

[0073] In some embodiments, the one or more heating elements 104 or the one or more cooling elements 108 may be shaped with various cross-sectional profiles to increase heat exchange with both the gas and the displacer segments. The thermally-conductive hot displacer segment 118 may include cavities 302 shaped to complement the one or more heating elements 104, and the thermally-conductive cold displacer segment 124 may include cavities 304 shaped to complement the one or more cooling elements 108. The cross-sectional shape of the heating elements 104, cooling elements 108, and corresponding cavities 302, 304 in the displacer segments may be selected to maximize surface area for heat transfer while accommodating manufacturing and assembly considerations.

[0074] In some embodiments, the one or more heating elements 104 or the one or more cooling elements 108 may be shaped with a circular cross-section in a plane orthogonal to a longitudinal axis between the hot end 106 and the cold end 110 of the cylinder 102. Circular cross-sections may provide uniform heat distribution and may simplify manufacturing of both the heating elements 104 or cooling elements 108 and the corresponding cavities 302, 304 in the displacer segments.

[0075] In some embodiments, the one or more heating elements 104 or the one or more cooling elements 108 may be shaped with a non-circular cross-section in a plane orthogonal to a longitudinal axis between the hot end 106 and the cold end 110 of the cylinder 102. Non-circular cross-sections may include, but are not limited to, fins, star shapes, lobed profiles, or other geometries that increase surface area compared to circular cross-sections of equivalent volume. For example, the heating elements 104 or cooling elements 108 may be shaped as fins extending radially from a central axis, which may increase the surface area available for heat transfer with both the gas and the displacer segments. As another example, the heating elements 104 or cooling elements 108 may be shaped with a star-shaped cross-section, similar to a Torx screwdriver profile, with the corresponding cavities 302, 304 in the displacer segments shaped to complement the star-shaped heating elements 104 or cooling elements 108, similar to a Torx screw head. These non-circular cross-sectional shapes may increase heat exchange between the heating elements 104 or cooling elements 108 and the gas, as well as between the heating elements 104 or cooling elements 108 and the respective displacer segments.

[0076] Various additional techniques may be utilized to enhance heat transfer to or from the thermally-conductive hot displacer segment 118 and / or the thermally-conductive cold displacer segment 124. Such techniques may incorporate any type of heat transfer mechanism including, but not limited to, convection, conduction, or radiation.

[0077] In some embodiments, the thermal pump 100 or the piston assembly 112 may include a coating or surface structures on the thermally-conductive hot displacer segment 118 or the thermally-conductive cold displacer segment 124 to promote radiative heat transfer. Radiative heat transfer may be particularly effective for the thermally-conductive hot displacer segment 118 when the one or more heating elements 104 operate at elevated temperatures, such as temperatures above approximately 300°C, where radiative heat transfer becomes a significant mode of heat exchange.

[0078] For examle, a coating on the thermally-conductive hot displacer segment 118 or the thermally-conductive cold displacer segment 124 may include a black coating. The term "black coating" as used herein refers to a coating that is absorptive for radiated light in a wavelength range corresponding to the operating temperature of the heating elements 104 or cooling elements 108, which may include infrared wavelengths. The black coating may not necessarily appear visually black but may be characterized by high absorptivity for infrared radiation emitted by the heating elements 104 or cooling elements 108. Examples of black coatings may include, but are not limited to, high-emissivity paints, ceramic coatings, or oxide coatings that exhibit high absorptivity in the infrared spectrum.

[0079] In some embodiments, the thermally-conductive hot displacer segment 118 may include an anodized aluminum surface to enhance infrared absorption for radiative heat transfer. Anodized aluminum surfaces comprise aluminum oxide, which is chemically similar to sapphire and exhibits high absorptivity for infrared radiation. The anodized aluminum surface may absorb infrared radiation emitted by the one or more heating elements 104 during the cooling position, thereby facilitating heat transfer from the heating elements 104 to the thermally-conductive hot displacer segment 118 even when the thermally-conductive hot displacer segment 118 is not in direct contact with the heating elements 104. This radiative heat transfer mechanism may be particularly effective when the heating elements 104 operate at temperatures where radiative heat transfer is a dominant mode of heat exchange, such as temperatures above approximately 500°C.

[0080] In some embodiments, surface structures may be provided on the thermally-conductive hot displacer segment 118 or the thermally-conductive cold displacer segment 124 to enhance radiative heat transfer. The surface structures may include textured surfaces, patterned surfaces, or micro-structured and nano-structured surfaces that increase the effective surface area for radiative heat absorption or emission. For example, the thermally-conductive hot displacer segment 118 may include surface features having micrometer-scale or nanometer-scale dimensions, such as micro-pillars, nano-pillars, micro-grooves, or nano-textured surfaces, which may reduce reflectivity and increase absorptivity for infrared radiation. In some cases, periodic or quasi-periodic surface structures at the micrometer or nanometer scale may create optical effects that enhance absorption of radiation at wavelengths corresponding to the operating temperature of the heating elements 104. Such surface structures may be formed through various fabrication techniques including, but not limited to, laser texturing, chemical etching, anodization processes, or deposition of structured coatings. The combination of surface structures with absorptive coatings may further enhance radiative heat transfer between the heating elements 104 and the thermally-conductive hot displacer segment 118.

[0081] In some embodiments, the one or more heating elements 104 may be configured to transfer heat to the thermally-conductive hot displacer segment 118 primarily through radiative heat transfer rather than conductive heat transfer. For example, the heating elements 104 may include glowing spirals or other radiating structures that emit infrared radiation toward the thermally-conductive hot displacer segment 118. In such configurations, the heating elements 104 may not require direct contact with the thermally-conductive hot displacer segment 118, which may simplify the mechanical design of the piston assembly 112 and reduce wear between the heating elements 104 and the displacer segments.

[0082] In some embodiments, the one or more heating elements 104 may include a transparent material that allows radiation from a heat source to pass through the heating elements 104 and directly heat the thermally-conductive hot displacer segment 118. In such configurations, the heat source may be positioned behind or within the heating elements 104, and the radiation from the heat source may pass through the transparent heating elements 104 to be absorbed by the thermally-conductive hot displacer segment 118.

[0083] In some embodiments, the thermally-conductive hot displacer segment 118 and / or the thermally-conductive cold displacer segment 124 may include active heating or cooling elements integrated within the displacer segment. The active heating or cooling elements integrated within the displacer segment may turn the displacer into an extended heater or cooler, thereby increasing the heat exchange capacity of the thermal pump 100. For example, the thermally-conductive hot displacer segment 118 may include resistive heating elements, inductive heating elements, or other active heating elements that supplement the heat absorbed from the one or more heating elements 104 at the hot end 106 of the cylinder 102. Similarly, the thermally-conductive cold displacer segment 124 may include thermoelectric cooling elements, fluid cooling channels, or other active cooling elements that supplement the cooling provided by the one or more cooling elements 108 at the cold end 110 of the cylinder 102. The active heating or cooling elements integrated within the displacer segments may be controlled independently or in coordination with the one or more heating elements 104 and the one or more cooling elements 108 to optimize heat exchange during each phase of operation.

[0084] In some embodiments, the thermal pump 100 may be a part of or integrated into a light source. For example, the thermal pump 100 may be incorporated into a light source for thermal management, gas delivery, flow control, or pressure management. In flow-through light source configurations, the thermal pump 100 may circulate gas through a plasma region or plasmatron to maintain controlled gas flow at elevated temperatures. Light source systems that may utilize the thermal pump 100 may include, but are not limited to, broadband plasma (BBP) light sources, plasma light sources, or other light sources requiring controlled gas flow at elevated temperatures. The cleanliness characteristics of the thermal pump 100 disclosed herein may be particularly beneficial for light source applications where contamination control is important, as the thermal pump 100 design may reduce or eliminate outgassing and other contamination sources that may be problematic with alternative pump technologies. Such light sources may be utilized in various application environments including, but not limited to, metrology systems, inspection systems, lithography systems, or other systems requiring high-intensity or broadband illumination.

[0085] FIG. 4 illustrates a flowchart for a method 400 for operating a thermal pump, in accordance with one or more embodiments of the present disclosure.

[0086] In some embodiments, the method 400 includes a step 402 of placing a piston assembly within a cylinder having a hot end with one or more heating elements and a cold end with one or more cooling elements. The piston assembly may comprise a regenerator, a hot displacer, and a cold displacer. The hot displacer may include a thermally-conductive hot displacer segment shaped to surround the one or more heating elements when the piston assembly is in a cooling position. The hot displacer may further include a thermally-insulating hot segment between the thermally-conductive hot displacer segment and the regenerator. The cold displacer may include a thermally-conductive cold displacer segment shaped to surround the one or more cooling elements when the piston assembly is in a heating position. The cold displacer may further include a thermally-insulating cold segment between the thermally-conductive cold displacer segment and the regenerator. For example, with reference to the thermal pump 100 described with respect to FIGS. 1 and 3, the step 402 may include placing the piston assembly 112 within the cylinder 102, where the piston assembly 112 comprises the regenerator 114, the hot displacer 116 with the thermally-conductive hot displacer segment 118 and the thermally-insulating hot displacer segment 120, and the cold displacer 122 with the thermally-conductive cold displacer segment 124 and the thermally-insulating cold displacer segment 126.

[0087] With continued reference to FIG. 4, in some embodiments, the method 400 includes a step 404 of moving the piston assembly to the cooling position. In the cooling position, the one or more cooling elements and the thermally-conductive cold displacer segment cool gas near the cold end of the cylinder, and the one or more heating elements heat the thermally-conductive hot displacer segment. For example, with reference to the thermal pump 100, the step 404 may include moving the piston assembly 112 toward the hot end 106 of the cylinder 102 such that the thermally-conductive hot displacer segment 118 surrounds the heating elements 104. In this cooling position, the cooling elements 108 and the thermally-conductive cold displacer segment 124 may cool gas near the cold end 110 of the cylinder 102, while the heating elements 104 heat the thermally-conductive hot displacer segment 118. The thermally-conductive cold displacer segment 124, having been pre-cooled during a previous heating position, may provide additional cooling surfaces that participate in the heat exchange process with the gas. Simultaneously, the thermally-conductive hot displacer segment 118 may absorb and store thermal energy from the heating elements 104, preparing the thermally-conductive hot displacer segment 118 to participate in heating the gas during a subsequent heating position.

[0088] As further shown in FIG. 4, in some embodiments, the method 400 includes a step 406 of moving the piston assembly to the heating position. In the heating position, the one or more heating elements and the thermally-conductive hot displacer segment heat gas near the hot end of the cylinder, and the one or more cooling elements cool the thermally-conductive cold displacer segment. For example, with reference to the thermal pump 100, the step 406 may include moving the piston assembly 112 toward the cold end 110 of the cylinder 102 such that the thermally-conductive cold displacer segment 124 surrounds the cooling elements 108. In this heating position, the heating elements 104 and the thermally-conductive hot displacer segment 118 may heat gas near the hot end 106 of the cylinder 102, while the cooling elements 108 cool the thermally-conductive cold displacer segment 124. The thermally-conductive hot displacer segment 118, having been pre-heated during the cooling position in the step 404, may provide additional heating surfaces that participate in the heat exchange process with the gas. Simultaneously, the thermally-conductive cold displacer segment 124 may absorb thermal energy from the cooling elements 108, preparing the thermally-conductive cold displacer segment 124 to participate in cooling the gas during a subsequent cooling position.

[0089] In some embodiments, the method 400 may include alternating between the step 404 and the step 406 to facilitate continuous heat exchange and gas flow within the cylinder. The alternation between the cooling position and the heating position may enable continuous operation of both the one or more heating elements and the one or more cooling elements throughout the thermal cycle, as the thermally-conductive hot displacer segment and the thermally-conductive cold displacer segment function as thermal energy storage components that are charged during one phase and discharged during the opposing phase.

[0090] Any of the methods described herein may include storing results of one or more steps of the method embodiments in memory. The results may include any of the results described herein and may be stored in any manner known in the art. The memory may include any memory described herein or any other suitable storage medium known in the art. After the results have been stored, the results can be accessed in the memory and used by any of the method or system embodiments described herein, formatted for display to a user, used by another software module, method, or system, and the like. Furthermore, the results may be stored “permanently,”“semi-permanently,” temporarily,” or for some period of time. For example, the memory may be random access memory (RAM), and the results may not necessarily persist indefinitely in the memory.

[0091] It is further contemplated that each of the embodiments of the method described above may include any other step(s) of any other method(s) described herein. In addition, each of the embodiments of the method described above may be performed by any of the systems described herein.

[0092] One skilled in the art will recognize that the herein described components operations, devices, objects, and the discussion accompanying them are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar is intended to be representative of its class, and the non-inclusion of specific components, operations, devices, and objects should not be taken as limiting.

[0093] As used herein, directional terms such as “top,”“bottom,”“over,”“under,”“upper,”“upward,”“lower,”“down,” and “downward” are intended to provide relative positions for purposes of description, and are not intended to designate an absolute frame of reference. Various modifications to the described embodiments will be apparent to those with skill in the art, and the general principles defined herein may be applied to other embodiments.

[0094] With respect to the use of substantially any plural and / or singular terms herein, those having skill in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations are not expressly set forth herein for sake of clarity.

[0095] The herein described subject matter sometimes illustrates different components contained within, or connected with, other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "connected," or "coupled," to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being "couplable," to each other to achieve the desired functionality. Specific examples of couplable include but are not limited to physically mateable and / or physically interacting components and / or wirelessly interactable and / or wirelessly interacting components and / or logically interacting and / or logically interactable components.

[0096] Furthermore, it is to be understood that the invention is defined by the appended claims. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” and the like). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., “a” and / or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, and the like” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, and the like). In those instances where a convention analogous to “at least one of A, B, or C, and the like” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, and the like). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

[0097] It is believed that the present disclosure and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the components without departing from the disclosed subject matter or without sacrificing all of its material advantages. The form described is merely explanatory, and it is the intention of the following claims to encompass and include such changes. Furthermore, it is to be understood that the invention is defined by the appended claims.

Claims

1. A thermal pump, comprising: a cylinder having a hot end and a cold end;one or more heating elements positioned at the hot end;one or more cooling elements positioned at the cold end; anda piston assembly movable within the cylinder, wherein the piston assembly comprises: a regenerator;a hot displacer, wherein the hot displacer includes a thermally-conductive hot displacer segment shaped to surround the one or more heating elements when the piston assembly is in a cooling position, wherein the hot displacer further includes a thermally-insulating hot displacer segment between the thermally-conductive hot displacer segment and the regenerator; a cold displacer, wherein the cold displacer includes a thermally-conductive cold displacer segment shaped to surround the one or more cooling elements when the piston assembly is in a heating position, wherein the cold displacer further includes a thermally-insulating cold displacer segment between the thermally-conductive cold displacer segment and the regenerator; wherein, in the cooling position: the one or more cooling elements and the thermally-conductive cold displacer segment both cool gas near the cold end of the cylinder; andthe one or more heating elements heat the thermally-conductive hot displacer segment; andwherein, in the heating position: the one or more heating elements and the thermally-conductive hot displacer segment both heat gas near the hot end of the cylinder; andthe one or more cooling elements cool the thermally-conductive cold displacer segment.

2. The thermal pump of claim 1, wherein at least one of the thermally-conductive hot displacer segment, the thermally-conductive cold displacer segment, or the regenerator comprises:at least one of aluminum, an aluminum alloy, copper, or a copper alloy.

3. The thermal pump of claim 1, wherein at least one of the thermally-insulating hot displacer segment or the thermally-insulating cold displacer segment comprises:at least one of a glass or a ceramic.

4. The thermal pump of claim 1, wherein at least one of the thermally-insulating hot displacer segment or the thermally-insulating cold displacer segment comprises:stacked metal plates with gaps therebetween.

5. The thermal pump of claim 1, wherein at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment are formed as different components.

6. The thermal pump of claim 1, wherein at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment are formed as a monolithic component providing thermal insulation in at least an axial direction between the hot end and the cold end of the cylinder.

7. The thermal pump of claim 6, wherein the monolithic component comprises:at least one of graphite or carbon fiber.

8. The thermal pump of claim 1, wherein the regenerator, the thermally-conductive hot displacer segment and the thermally-insulating hot displacer segment are divided into multiple components associated with different ones of the one or more heating elements.

9. The thermal pump of claim 1, wherein the regenerator, the thermally-conductive cold displacer segment and the thermally-insulating cold displacer segment are divided into multiple components associated with different ones of the one or more cooling elements.

10. The thermal pump of claim 1, further comprising:at least one of a coating or surface structures on at least one of the thermally-conductive hot displacer segment or the thermally-conductive cold displacer segment to promote radiative heat transfer.

11. The thermal pump of claim 10, wherein the thermally-conductive hot displacer segment includes a black coating.

12. The thermal pump of claim 1, wherein the thermally-conductive hot displacer segment includes cavities shaped to complement the one or more heating elements, wherein the thermally-conductive cold displacer segment includes cavities shaped to complement the one or more cooling elements.

13. The thermal pump of claim 12, wherein at least one of the one or more heating elements or the one or more cooling elements are shaped with a circular cross-section in a plane orthogonal to a longitudinal axis between the hot end and the cold end of the cylinder.

14. The thermal pump of claim 12, wherein at least one of the one or more heating elements or the one or more cooling elements are shaped with a non-circular cross-section in a plane orthogonal to a longitudinal axis between the hot end and the cold end of the cylinder.

15. A piston assembly for a thermal pump, comprising: a regenerator;a hot displacer, wherein the hot displacer includes a thermally-conductive hot displacer segment shaped to surround one or more heating elements in a hot end of a cylinder when the piston assembly is in a cooling position in the cylinder, wherein the hot displacer further includes a thermally-insulating hot displacer segment between the thermally-conductive hot displacer segment and the regenerator; a cold displacer, wherein the cold displacer includes a thermally-conductive cold displacer segment shaped to surround one or more cooling elements in a cold end of the cylinder when the piston assembly is in a heating position in the cylinder, wherein the cold displacer further includes a thermally-insulating cold displacer segment between the thermally-conductive cold displacer segment and the regenerator; andwherein, in the cooling position: the one or more cooling elements and the thermally-conductive cold displacer segment both cool gas near the cold end of the cylinder; andthe one or more heating elements heat the thermally-conductive hot displacer segment; andwherein, in the heating position: the one or more heating elements and the thermally-conductive hot displacer segment both heat gas near the hot end of the cylinder; andthe one or more cooling elements cool the thermally-conductive cold displacer segment.

16. The piston assembly of claim 15, wherein at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment are formed as different components17. The piston assembly of claim 15, wherein at least some of the regenerator, the thermally-conductive hot displacer segment, the thermally-insulating hot displacer segment, the thermally-conductive cold displacer segment, or the thermally-insulating cold displacer segment are formed as a monolithic component providing thermal insulation in at least an axial direction between the hot end and the cold end of the cylinder.

18. The piston assembly of claim 15, wherein the regenerator, the thermally-conductive hot displacer segment and the thermally-insulating hot displacer segment are divided into multiple components associated with different ones of the one or more heating elements.

19. The piston assembly of claim 15, wherein the regenerator, the thermally-conductive cold displacer segment and the thermally-insulating cold displacer segment are divided into multiple components associated with different ones of the one or more cooling elements.

20. The piston assembly of claim 15, further comprising:at least one of a coating or surface structures on at least one of the thermally-conductive hot displacer segment or the thermally-conductive cold displacer segment to promote radiative heat transfer.

21. A method comprising: placing a piston assembly within a cylinder having a hot end with one or more heating elements and a cold end with one or more cooling elements, wherein the piston assembly comprises: a regenerator;a hot displacer, wherein the hot displacer includes a thermally-conductive hot displacer segment shaped to surround the one or more heating elements when the piston assembly is in a cooling position, wherein the hot displacer further includes a thermally-insulating hot displacer segment between the thermally-conductive hot displacer segment and the regenerator;a cold displacer, wherein the cold displacer includes a thermally-conductive cold displacer segment shaped to surround the one or more cooling elements when the piston assembly is in a heating position, wherein the cold displacer further includes a thermally-insulating cold displacer segment between the thermally-conductive cold displacer segment and the regenerator;moving the piston assembly to the cooling position, wherein: the one or more cooling elements and the thermally-conductive cold displacer segment both cool gas near the cold end of the cylinder; andthe one or more heating elements heat the thermally-conductive hot displacer segment; andmoving the piston assembly to the cooling position, wherein: the one or more heating elements and the thermally-conductive hot displacer segment both heat gas near the hot end of the cylinder; andthe one or more cooling elements cool the thermally-conductive cold displacer segment.

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