RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 61/599,232 filed February 15, 2012, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

[0002] Thermodynamic cycle-based machines such as Stirling engines and other devices often use a containment vessel having a containment chamber and heat exchangers along with other components to help convert heat into mechanical motion and to use such mechanical motion to provide cooling or electricity. Conventional heat exchanger assemblies for use with thermodynamic cycle-based machines typically contain many parts that have demanding assembly requirements.

[0003] Containment vessels and other components of thermodynamic cycle-based machines are often subjected to extreme temperature environments for extended periods of time. Therefore, exotic materials having properties suitable for use in extreme temperature environments have been used to form heat exchanger assemblies. In addition, forming exotic materials into complex shapes such as annular heat exchangers is difficult and costly. As an example, construction is often challenging because a large heat transfer surface area is usually required to be in contact with working gases.

[0004] A typical application for a heater exchanger is found on a Stirling cycle electric power generator. One typical configuration has a movable displacer contained within an enclosed working chamber. The displacer forms a movable piston within the generator housing, transferring working fluid back and forth between a compression space (a low temperature space) and an expansion space (an extreme temperature space). A power extraction piston is provided in fluid communication with the compression space. Additionally, a fluid flow path transfers working fluid from the expansion space to the compression space through a gas heater, a annular regenerator which is disposed within a housing and surrounds to the displacer, and a gas cooler, respectively. Heat is applied to a heat transfer assembly, causing the displacer to reciprocate within a cylinder between the compression and expansion spaces. [0005] As a result, working fluid is transferred cyclically back and forth through the internal heat exchangers. The working gas is cooled as it flows through the gas cooler, adjacent to the compression space, and heated as it flows through the gas heater, adjacent to the expansion space. Depending on the direction of fluid flow, an annular regenerator, which is disposed around the displacer, acts as a heat exchanger that extracts heat from the gas passing from the gas heater to the gas cooler, and stores it for a portion of an operating cycle. The stored heat is returned to the gas later as the gas flows from the gas cooler to the gas heater. External heat is supplied to the gas heater at the hot end where heat is applied by a source to the exterior of the heat exchange assembly. Pressure oscillations in the compression chamber (low temperature space) cause the working piston of the linear alternator to reciprocate, creating a source of electrical power therefrom. Alternatively, the cycle can be run in reverse to provide coiling. In general, two heat exchange assembly designs are typically used to transfer heat to the working fluid as it passes through the gas heater: a tubular design or a finned design.

[0006] Tubular or finned designs tend to have high stresses at the interfaces where the geometry varies, have high flow losses at those interfaces and are typically expensive to produce with complicated welds or braze joints. The tube and fin heat exchangers are typically fluid cooled with the fluid boundary and subsequent tube interfaces adjacent to the high containment vessel of the Stirling cycle which leads to complicated high stress designs.

[0007] The constraints on existing designs, such as those listed above, are often interconnected with other components disposed in a common housing. For example, the length of an annular regenerator is usually controlled not by the Stirling cycle optimum but instead by the length required to reduce thermal bending stresses to an acceptable level for structural life. The inner and outer diameters of an annular regenerator are driven by the displacer size and the heat exchanger size. The rejector heat exchanger inside diameter, outside diameter, and length are driven by the displacer size, the acceptor outside diameter, and the height of the displacer body / location of the flexure stack within the displacer.

[0008] Accordingly, a need therefore exists to address the design problems, component relationships and costs associated with the heat exchanger designs described above. Embodiments of the invention address these design problems and provide various advantages relating to regenerator and other heat exchanger configurations for use in thermodynamic cycle-based machines such as cooling or power generating devices. SUMMARY OF INVENTION

[0009] In part, the invention relates to a heat exchanger assembly suitable for use with a thermodynamic cycle-based machine such as, for example, a thermal energy converting or transfer device or a cooling device. Stirling engine based devices and other machines can be used in various embodiments. The heat exchanger-based embodiments described herein can be used for heating, cooling, power generation, and other purposes. In one embodiment, an exemplary heat exchanger assembly includes an acceptor section, a regenerator section, and a rejector section. Each of the acceptor section, the regenerator section, and the rejector section are heat exchangers in one embodiment. In one embodiment, each of the sections can be parts of a unitary tube. In one embodiment, each of the sections can be a tube. One or more of the tubes can be a canister. The canister, one or more tubes, a regenerator material and a containment vessel can also include a working material. The working material is pressurized in one embodiment. Various suitable working materials can be used without limitation such as a gas, a liquid, a solid, a fluid, particles, slurries, and combinations thereof. In one embodiment, the working material is gas such as helium, hydrogen, an inert gas, and other gases.

[0010] In one embodiment, one or more tubes can be connected in series or otherwise to form a heat exchanger assembly. The heat exchanger assembly can include, without limitation, a first, second, and third section. Each section can be a separate tube. In addition, other transitional sections such as tubes or working material transferring components can be in fluid communication with one or more of the first, section or third section. Each section can be any suitable structure which defines a channel, bore, or other space through which a gas may flow. In one embodiment, a regenerator material is disposed in one or more sections of the tube or tubes. The heat exchanger assembly can include a tube having an expanded or bulged section disposed between either end of a tube. In one embodiment, regenerator material is disposed in such an expanded or bulged section. In one embodiment, the expanded or bulged section of one tube is replaced with another tube which can also be referred to as a canister. Thus, in one embodiment, the heat exchanger or regenerator assembly includes a first tube, a second or middle tube, and a third tube. The second or middle tube is disposed between the first tube and the third tube. The regenerator material is at least disposed in the second or middle tube in one embodiment. [0011] In one embodiment, a plurality of regenerator heat exchangers is arranged such that they surround the outer surface of a containment vessel. In one embodiment, each regenerator heat exchanger is a canister coupled to a first tube and a second tube. The canister can have an outer surface defining a plurality of holes or channels configured to receive or connect with a plurality of acceptor or rejector ports. In one embodiment, each canister, which can include one or more tubes, has one or more inlet ports and one or more outlet ports. In one embodiment, an inlet port and an outlet port are formed by an endcap which defines a hole or channel. In one embodiment, the endcap is tapered such as by for example having a conical portion or section. In one embodiment, the canister is tapered such as by for example having a conical portion or section. The taper can also be that of a smooth curve. In one embodiment, each canister includes or is in thermal communication with an acceptor and rejector. In one embodiment, the acceptor terminates at a port such as an inlet or outlet port and is formed from a tube that has a substantially straight portion and an angled or substantially curved or tapered portion. In one embodiment, the rejector terminates at a port such as an inlet or outlet port and is formed from a tube that has a substantially straight portion and an angled or substantially curved or tapered portion.

[0012] In one embodiment, the invention relates to a regenerator assembly which includes a tube and a regenerator material disposed therein. In one embodiment, the regenerator material is plurality of fibers having a circular cross-section. Other regenerator materials and forms can be used, without limitation, such as is known in the art and as otherwise described herein. The regenerator material can be disposed in a canister sandwiched between a first tube having a first endcap and a second tube having a second endcap. The first and second endcaps are connected to the canister and each define a bore through which a working material can pass into the regenerator material and along the first and second tubes. The regenerator assembly includes a working material such as a gas. The working material is pressurized. In one embodiment a plurality of regenerator assemblies are coupled to a containment vessel via a plurality of channels defined by a wall of the containment vessel.

[0013] In one embodiment, the acceptor tube and rejector tube sections have smaller diameters relative to the regenerator tube section such as a regenerator canister. In one embodiment, endcaps having ports for working material flow are disposed on either side of the regenerator material. In one embodiment, the endcaps are adjacent to the ends of the regenerator section or canister. The endcaps can be adjacent to or in fluid communication with the interface between a working material and the regenerator material in one embodiment. The endcaps can be puck shaped in one embodiment or otherwise have a substantially cylindrical geometry.

[0014] In one aspect, the invention relates to a heat exchanger assembly. The heat exchanger assembly includes a regenerator assembly that includes, a regenerator heat exchanger that includes a first tube section defining a first bore and a regenerator material disposed in the first bore; an acceptor heat exchanger that includes a second tube section defining a second bore, a first regenerator interface and an acceptor port; and a rejector heat exchanger that includes a third tube section defining a third bore, a second regenerator interface and a rejector port, wherein the regenerator material is disposed between the first regenerator interface and the second regenerator interface.

[0015] In one embodiment, each of the first tube section, the second tube section, and the third tube section are each a section of a unitary tube. In one embodiment, the heat exchanger further includes a working material disposed in the first bore, the second bore, and the third bore. In one embodiment, the heat exchanger wherein the first tube section is a canister and further includes a first endcap defining a first regenerator port and a second endcap defining a second regenerator port, wherein the first bore is in fluid communication with the first regenerator port and the second regenerator port. In one embodiment, the heat exchanger further includes a containment vessel having a vessel wall, an inner surface, an outer surface, and a longitudinal axis, wherein the vessel wall and outer surface defines a first channel and wherein the inner surface at least partially defines a containment chamber.

[0016] In one embodiment, either the acceptor port or the rejector port is connected to the first channel and wherein the first bore, the second bore, and the third bore are in fluid communication with the containment chamber. In one embodiment, the first tube section is a canister and wherein the canister is suspended relative to the outer surface by the second tube section or the third tube section. In one embodiment, the heat exchanger further includes a working material disposed in the containment chamber and a thermodynamic cycle-based machine in thermal communication with the working material. In one embodiment, the regenerator assembly is one of N regenerator assemblies and further includes the N regenerator assemblies.

[0017] In one embodiment, N ranges from 2 to 300. In one embodiment, the N regenerator heat exchangers are arranged around the longitudinal axis. In one embodiment, the first tube section is a canister that includes a first endcap having a first plurality of ports and a second endcap having a second plurality of ports, wherein the second tube section is connected to one of the first plurality of ports, wherein the third tube section is connected to one of the second plurality of ports and further includes one or more tube sections, wherein the one or more tube sections are connected to the other first plurality of ports and the other second plurality of ports.

[0018] In one embodiment, wherein the regenerator material is selected from the group consisting of a wire, a mesh, one or more spheres, a porous solid, stainless steel, a plastic material, a polymer-based material, a non-ferrous material. In one embodiment, the regenerator assembly is configured to accept or reject an amount of average power through heat transfer, wherein the amount of average power rejected or accepted ranges from about 1 Watts to about 2000 Watts. In one embodiment, the N regenerator assemblies are arranged relative to each other based on a pressure drop for each such regenerator assembly. In one embodiment, the working material is a gas and the thermodynamic cycle-based machine is a Stirling cycle-based machine.

[0019] In one aspect, the invention relates to a heat exchanger assembly. The heat exchanger assembly includes a containment vessel having an outer surface defining a plurality of vessel ports; a plurality of first heat exchangers, each first heat exchanger defining a first heat exchanger bore and a first heat exchanger port; a plurality of regenerator heat exchangers, each regenerator heat exchanger defining a regenerator bore; a plurality of second heat exchangers, each second heather exchanger defining a second heat exchanger bore, wherein the plurality of regenerator heat exchangers are suspended relative to or supported by the outer surface and wherein each vessel port is connected to each first heat exchanger port.

[0020] In one embodiment, each regenerator heat exchanger is a section of a unitary tube. In one embodiment, each regenerator heat exchanger is a canister that includes a canister body, a first end cap, a second end cap and a regenerator material disposed in the canister body. In one embodiment, the first end cap is a conical or curved endcap. In one embodiment, the heat exchanger assembly further includes a displacer, wherein the displacer is configured to reciprocate within the containment vessel and move a working material through each regenerator heat exchanger. In one embodiment, the plurality of regenerator heat exchangers includes between about 2 to about 300 regenerator heat exchangers. [0021] One advantage of the tubular heat exchanger assemblies is that they enable non- annular forms of Stirling machines. In addition, the tubular heat exchanger is configured to work with any thermodynamic cycle-based machine including any Stirling machine (alpha, beta, or gamma types). Embodiments of the invention are configured to avoid annular regenerators or regenerators disposed within a shared housing and a displacer or other moving thermodynamic cycle-based machine components.

BRIEF DESCRIPTION OF DRAWINGS

[0022] The figures are to be considered illustrative in all aspects and are not intended to limit the invention, the scope of which is defined only by the claims.

Figure 1 is a schematic diagram of a heat exchanger assembly or a component thereof according to an illustrative embodiment of the invention.

Figures 2A-2D are schematic diagrams of a heat exchanger assembly or a component thereof according to an illustrative embodiment of the invention.

Figure 3 is a schematic diagram of containment vessel configured to receive one or more heat exchangers according to an illustrative embodiment of the invention.

Figure 4 is a schematic diagram of a heat exchanger assembly and containment vessel according to an illustrative embodiment of the invention.

Figures 5A-5B are perspective views of a cross-section of a heat exchanger assembly according to an illustrative embodiment of the invention.

Figure 6 is a cross-sectional view of a heat exchanger assembly according to an illustrative embodiment of the invention.

Figures 7A is a cross-sectional view of a heat exchanger assembly according to an illustrative embodiment of the invention.

Figures 7B and 7C are perspective views of heat exchanger assemblies according to an illustrative embodiment of the invention. DETAILED DESCRIPTION

[0023] In one embodiment, the invention relates to a heat exchanger assembly such as a regenerator assembly for use with a thermodynamic cycle-based device such as a Stirling cycle machine. The heat exchanger assembly includes an acceptor heat exchanger, a regenerator heat exchanger, and a rejector heat exchanger and one or more assemblies. Typically, one heat exchanger assembly formed from one or more tubes is used. For example, a tube can be molded or formed to include a chamber or bulge having a larger diameter relative to the segments of the tube on either side of such a chamber or bulge. Alternatively, a first tube and a second tube can connect to a third tube or canister. A regenerator material is disposed in such a chamber or canister in one embodiment. Thus, one or more tubes or canisters can be connected in series.

[0024] Embodiments of the invention relate to a heat exchanger assembly that includes one or more tubes connected in series. As part of one embodiment, a regenerator material is sintered into or otherwise disposed in a bore of one more tubes. Thus, sections of the tubes such as substantially parallel, but separate sections can include sections of regenerator material. Multiple tubes can be selected to allow for material transitions (super alloy acceptor, steel rejector) or to allow for diameter changes. Additional details relating to such heat exchanger assemblies and other embodiments thereof are shown in Figures 1 and 2A-2D and otherwise described or depicted herein.

[0025] Figure 1 depicts an exemplary cross-section of a heat exchanger 10 that includes a tube 12. The tube 12 includes a material shaped to form a tube wall 15. In one embodiment, the material forming the tube is a metal, polymer-based material, or other suitable material. The tube 12 has a regenerator material 20 disposed therein. The regenerator material 20 is typically disposed along a section of the tube 12 having a length that ranges from about 10 mm to about 100 mm. The diameter of the tube 12 can range from about 3 mm to about 100 mm. The regenerator material 20 is typically configured to provide heat transfer relative to a section of the tube 10 preceding the section of the tube 12 which includes regenerator material 20 and a subsequent section of the tube 12. In one embodiment, the tube 12 includes a first section, a second section, and the third section, each of these sections can be selected from a group consisting of an acceptor, a regenerator, and a rejector. In one embodiment, various lengths of a given tube define a substantially cylindrical cavity which includes a regenerator material. A working material such as a gas can be disposed with the tube wall 15 and the regenerator material 20.

[0026] Additional features and configurations relating to exemplary embodiments of a heat exchanger assembly are described below with respect to Figures 2A-2D. Various components can be used for such assemblies, including, without limitation, regenerator materials, a unitary tube, one or more tubes, multiple substantially straight tubes, multiple curved tubes, one or more formed tubes, endcaps, joints, swaged regions, other components described herein and combinations thereof. For example, in one embodiment, an entire regenerator assembly including a regenerator exchanger with a regenerator material and a rejector heat exchanger and an acceptor heat exchanger can be formed as a single structure such as a unitary structure. In one embodiment, hydro-forming is used to form such a structure. The cross-section of a given tube, endcap, or canister used in a heat exchanger assembly can be of any suitable shape, geometry, or configuration, including without a limitation, an elliptical cross-section, a circular cross-section, a polygonal cross-section, an irregular cross-section, a symmetric cross-section, an asymmetric cross-section a smooth curve, and combinations thereof.

[0027] In one embodiment, the regenerator material located between an acceptor heat exchanger and a rejector heat exchanger stores and delivers thermal energy for use by portion of a device's thermodynamic cycle such as an engine cycle. Various regenerator materials can be used, without limitation, as is suitable for a particular level of heat transfer or the requirements associated with the thermodynamic cycle-based machine or other device to which the heat exchanger assembly will be in thermal communication therewith. In one embodiment, the regenerator material is configured such that the ratio of its surface area to its volume is greater than two.

[0028] Figure 2A shows an arrangement of heat exchangers. Specifically, a first heat exchanger El, a regenerator heat exchanger R, and a third heat exchanger E2 are shown. A single tube 10a is divided into the arrangement of heat exchangers shown. In this embodiment, a tube wall 15 defines a bore B l for one end of the tube 10a. The tube 10a may also define a second bore B2 at the other end of the tube. In one embodiment, the two bores Bl and B2 are the same. Regenerator material 20 is disposed in section R corresponding to the regenerator heat exchanger. The regenerator heat exchanger can also define a bore or chamber which has a thickness that is substantially the same as the thickness of bores Bl and B2 or that differs from such bores B l or B2. In one embodiment, the first heat exchanger El is an acceptor heat exchanger. Alternatively, the first heat exchanger is a rejector heat exchanger in another embodiment. In one embodiment, the second heat exchanger E2 is an acceptor heat exchanger. Alternatively, the second heat exchanger is a rejector heat exchanger in another embodiment.

[0029] The regenerator material is configured to absorb heat from a heat transfer material also referred to herein as a working material such as a fluid or gas or other phase when it enters from the region of an adjacent heat exchanger such as El (or E2) and to heat the heat transfer material when it passes from the other adjacent heat exchanger such as E2 (or El). One or more of the density, area, volume and other parameters of the regenerator material can vary along the length of the regenerator heat exchanger.

[0030] The regenerator material 20 can be a variety of materials. With respect to the first exchanger El, the bore B l of the tube can include a coolant or other working material 25. With respect to the second exchanger E2, the bore B2 of the tube 10a can include a coolant or other working material 27. Working material 25 and 27 are typically the same (although have different temperatures during operation) can be a solid, liquid, or gas and also include combination thereof. In one preferred embodiment, the working material 25, 27 includes a gas such as helium or hydrogen, for example. The working material 25, 27 is also disposed in a containment chamber of a containment vessel in one embodiment. Various containment vessels can be used without limitation such a shells or caps having a wall configured to define a containment chamber.

[0031] In Figure 2B, heat exchanger assembly 10b includes a first heat exchanger El, a regenerator heat exchanger R, and a second heat exchanger E2. The heat exchanger assembly 10b can be fabricated using one tube as shown in Figure 2A. Alternatively, the heat exchanger can include a plurality of tubes or other components arranged in a sequential manner. As shown in Figure 2B, the first tube 29 has tube wall 30. A second tube 31 has a tube wall 33. A third tube 34 has a tube wall 35. In one embodiment, two or more of the tubes shown can be swaged to form a single unitary tube or other structure. The regenerator section R can define third a bore which can be substantially the same as the first and second bores B1, B2. [0032] As shown in Figure 2B tube 29 is disposed within tube 33 at joint 37a. As shown in Figure 2B tube 34 is disposed within tube 31 at joint 37b. In one embodiment, tube 31 is a canister. In Figure 2B, in one embodiment, a first regenerator interface and a second regenerator interface are disposed within tube wall 33 as shown by the boundary between the working material 25, 27 and the regenerator materials 20. In one embodiment, a transition section wherein one heat exchanger El and another one heat exchanger E2 joins are generator canister or tube 31 is formed by swaging the tube 31 such that tube 31 and the transition such as joint 37a and 37b are one piece. In one embodiment, swaging eliminates having to weld the tube to the regenerator canister or tube.

[0033] In Figure 2C, heat exchanger assembly 10c includes a first heat exchanger El, a regenerator heat exchanger R, and a second heat exchanger E2. Each of these exchangers can include a tube or other component. As shown in Figure 2C, a first tube 39 has tube wall 38. A second tube 42 has a tube wall 40. A third tube 44 has a tube wall 46. In one embodiment, two or more of the tubes shown can be swaged to form a single unitary tube or other structure. As shown, the bore of the regenerator section R is larger than bores B l, B2. Alternatively, the regenerator section R can define third a bore which can be substantially the same as the first and second bores Bl, B2. In one embodiment, tube 42 is a canister having tapered or angled or curved endcaps 47a, 47b. In one embodiment, endcaps 47a, and 47b are formed from tube wall 40. In another embodiment, endcaps 47a, and 47b are attached to tube wall 40 by swaging, welding, brazing, or another suitable attachment process.

[0034] In Figure 2D, heat exchanger assembly lOd includes a first heat exchanger El, a regenerator heat exchanger R, and a second heat exchanger E2. Each of these exchangers can include a tube or other component. As shown in Figure 2D, a first tube 48 has tube wall 48a. A second tube 49 has a tube wall 49a. A third tube 50 has a tube wall 50a. On either side of the regenerator material 20, a first tubular segment 51 and a second tubular segment 52 are shown. Each of these tubular segments 51, 52 are endcaps having a curved or conical cross- sectional portion in one embodiment. In one embodiment, two or more of the tubes shown can be swaged to form a single unitary tube or other structure. As shown, the bore of the regenerator section R is larger than bores Bl, B2. Alternatively, the regenerator section R can define third a bore which can be substantially the same as the first and second bores Bl, B2. In one embodiment, tube 50 is a canister having tapered or angled or curved endcaps 51, 52. In one embodiment, endcaps 47a, and 47b are formed from tube wall 50a. In another embodiment, endcaps 51, 52 are attached to tube wall 50a by swaging, welding, brazing, or another suitable attachment process.

[0035] The ends of the tubes shown in Figures 2A-2D define ports such as inlet or outlet ports which can be used to connect such ports or place them in thermal communication with channels or holes defined by the wall of a containment vessel. Each of the embodiments shown in Figure 2A-2D can be combined together in various configurations along with a containment vessel or other structure to form additional tubular heat exchanger assemblies. Each of the tubes shown in Figures 2A-2D can have various cross-sectional geometries. The tubes used in the regenerator section R can be canisters and other structures that define a chamber or cavity for the regenerator material 20 such as spheres, bulged or formed sections of a tube wall, a housing, or other suitable structures configured to contain a working material or a regenerator material.

[0036] An exemplary heater exchanger assembly component in the form of an exemplary containment vessel 55 is shown in Figure 3. In Figure 4 various heat exchangers are disposed relative to and connected to the containment vessel 55 of Figure 3. With respect to Figure 3, the containment vessel 55 includes a base 56a and an outer surface which includes a first annular or cylindrical region 56b, a second annular or cylindrical region 56c, and a curved endface 60. The outer surface of the containment vessel 55 includes a plurality of holes or channels disposed on endface 60. The containment vessel 55 has a vessel wall which defines an inner surface which contains a working material. The outer surface of the containment vessel includes a plurality of holes 62 which are defined by the vessel wall and/or the outer surface. In one embodiment, the thickness of the vessel wall ranges from about 4 to about 8 mm. The containment vessel 55 can be shaped in a variety of ways. In one embodiment, the containment vessel is a canister and has a substantially cylindrical shape. In one embodiment, the holes 62 are arranged in a symmetrical pattern around the longitudinal axis L of the containment vessel 55. For example, as shown in Figure 3, a first substantially circular arrangement of holes is disposed within a second substantially circular arrangement of holes on endface 60.

[0037] One or more tubes, such as the exemplary tubes depicted in Figures 1 and 2A-2D are arranged relative to a surface of the containment vessel 55 in some embodiments. The base of the containment vessel 56a is shown. For example, as shown in Figure 4, a heat exchanger assembly 70 includes multiple arrangements of tubes and/or tubes and canisters 77 such as N tubes, arranged relative to the containment vessel such that containment vessel is penetrated by and provides support for one or more tubes. Multiple tubes configured as a heat exchanger having a tapered or curved or angled tube section are shown in region El . Multiple tubes configured as a heat exchanger having a tapered or curved or angled tube section are shown in region E2. Multiple tubes configured as a heat exchanger having a tapered or curved or angled tube section are shown in region R. In one embodiment, an exemplary tube section of a heat exchanger assemble penetrates the containment vessel at an angle measured relative to a normal of the outer surface of the containment vessel such that the angle ranges from about 0 degrees to about 90 degrees. In one embodiment, the angle is about 55 degrees.

[0038] As shown in Figure 4, one or more tubes 77 or canisters 77 having a regenerator material disposed therein are arranged in a regenerator section R. One exemplary regenerator assembly or heat exchanger assembly can include a first tube 78a and a second tube 78b or canister 78b and a third tube 78c. In one embodiment, the containment vessel has an outer surface with one or more holes or channels defined by the wall of the containment vessel. One or more tubes are arranged such that the containment vessel is penetrated by such one or more tubes at a first region such as a hole 62 and a second region such as a hole 62 shown in Figure 3.

[0039] The first region can be disposed on the upper surface or upper portion of a side wall of the containment vessel. Second region can be disposed along a side wall of the containment vessel. The penetrations or holes defined by one or more of the tubes passing through the containment vessel can be arranged in a pattern such as a circular, elliptical, polygonal, or other pattern. The first region and the second region are typically separated by a distance. In one embodiment, a canister or tube such as canister or tube 78b can be connected to multiple tube sections from section El and multiple tube sections from section E2. In this way, fewer canister or tubes that include a regenerator material such as shown in section R can be used. The tube sections of section El can curve as shown by section 79. Such a curve allows the heat exchanger section to extend downward to a port such as a hole 62 in the endface 60. A working material such as helium or hydrogen gas circulates through the tubes shown in a substantially toroidal arrangement in Figure 4. The working material moves through the regenerator section R into a first heat exchanger section El such as a rejector and then continues down into the containment vessel 55 before being driven into heat exchanger section E2 such as an acceptor. The flow of working material can be reversed in various embodiments.

[0040] The joint between the tubes and between a given tube and the containment vessel can be formed using various methods, including without limitation, laser welding, brazing, inertia welding, soldering, applying adhesive, bonding, swaging, press fitting, metal inert gas (MIG) welding and tungsten inert gas (TIG) welding. A similar joint can be formed between the rejector end and the displacer housing vessel or thermodynamic cycle-based machine housing. In one embodiment, the thermodynamic cycle-based machine can be a Stirling machine. In one embodiment, the thermodynamic cycle-based machine can be a machine suitable for converting heat such as solar energy or energy from burning fuel into electricity or providing cooling in response to mechanical motion such as by a piston.

[0041] Figure 5A shows a cross-section of a heat exchanger 80 which has a regenerator heat exchange section R that includes a plurality of canisters C. Each canister C has a regenerator material disposed therein. A first section of heat exchangers El is disposed above the canisters. Below the regenerator section R a second section of heat exchangers El is disposed. The sections shown are disposed relative to containment vessel 82 which has a vessel wall having a thickness. The vessel wall of the vessel 82 defines a plurality of ports 83 such as holes or channels. These ports 83 allow the working material to circulate through the heat exchanger assembly 80 as shown such as up (or down) through a first tube section 87 then up (or down) through a regenerator section 88 and then up (or down) through a second tube section 85 before returning (or leaving from) containment vessel 82. In one embodiment, the diameter D of the containment vessel ranges from about 100 mm to about 300.

[0042] Figure 5B shows a cross-section of a heat exchanger 90 which has a regenerator heat exchange section R that includes a plurality of canisters C. Each canister C has a regenerator material 20 disposed therein. The canisters C surround a containment vessel 82 having a base 93. The containment vessel 92 defines a containment chamber which is penetrated by various ports from tubes in sections El and E2. In one embodiment, the canisters C include a cylindrical or puck shaped endcap or section 94. In one embodiment, the canisters C include a tapered or conical endcap or section 95. A plurality of tubular assemblies is shown. For example, a representative heat exchanger assembly includes a canister C, a tube section 97 and a tube section 98 with a conical or curved endcap 95 attached to one end of the canister C and defining a port. A second endcap 94 is attached to the other end of the canister C and also defines a port for the flow of a working material. This configuration and the others described herein avoid the challenges associated with annular regenerators disposed in a housing below a containment vessel such as vessel 92 shown.

[0043] Figure 6 shows a cross-section of a cooler or thermal energy converting apparatus 100 with an exemplary heat exchanger assembly 105 in thermal communication therewith. The apparatus 100 includes a converter, a piston, and a displacer as shown. The displacer of the machine is shown moving into a containment chamber 120 of a containment vessel The heat exchanger assembly 105 includes a plurality of tube sections or canisters similar to one or more embodiments shown in Figures 2A-2D, 4A, 5A and 5B.

[0044] In one embodiment, the containment vessel 120 has a side wall and an upper surface. The tubes in heat exchanger section E2 are arranged above the surface of vessel 120. The displacer moves into and out of the containment vessel 120 causing the working material to move throughout section El, R, and E2 of the assembly 105. In one embodiment a plurality of regenerators R are arranged as a band which is suspended in space relative to the containment vessel 120 by the one or more tubes such that they surround the upper surface of the containment vessel 120. In one embodiment, N regenerator assemblies surround or are otherwise connected to the outer surface of the containment vessel.

[0045] Figure 7A shows a top down view of a containment vessel outer surface 150 with a plurality of holes or ports 155 defined therein. As shown four canisters 160a, 160b, 160c, and 160d having a regenerator material disposed therein are arranged with respect to the surface 150 in a manner similar to the canisters C in Figure 5B. Instead of having one tube enter each of the canisters, multiple tubes can be entering one side of canister via ports 175 and leaving another side of the canisters by additional ports on the other side (not shown). In this embodiment, fewer canisters can be used. The working fluid can flow through ports 175 to ports 155 in the surface 150 through tubes (not shown).

[0046] Figure 7B and 7C shows a perspective view of heat exchangers 200 and 225. The heather exchanger 200 in Figure 7B includes a canister 205 such as a tube which defines a bore or chamber that includes a regenerator material disposed therein. Various tubes 210a, 210b, 210c, and 210d are shown extending from the sides of the canister 205. In one embodiment, these tubes are substantially parallel. A working material can flow from tube 210a through the regenerator material and out through a port such as port 212. The tubes shown in Figures 7B and 7C are in communication with a containment vessel in one embodiment. The tubes 210a and 210b extending from the bottom of the canister 205 can either be acceptor exchangers or rejector exchangers. Similarly, the tube 210c and 210d extending from the top of the canister 205 can either be acceptor exchangers or rejector exchangers.

[0047] In Figure 7C, a plurality of tubes are shown disposed at an angle relative to each other and extending from a canister 227. The canister includes a regenerator material. As shown, a working material can flow through the tubes 235a, 235b and into the canister 227 or in the reverse direction. As shown, a working material can flow through the tubes 235c, 235d and into the canister 227 or in the reverse direction. A port such as an end of a tube 240 can be used to connect to other tubes or otherwise being in communication with a working material and containment vessel. With respect to a given regenerator material containing canister, various tubes and ports can be arranged in various configurations and multiple tubes can be used to provide acceptor or rejector heat exchange.

[0048] Insulation can be placed or cast around the heat exchanger assemblies. The regenerator assemblies can be of various sizes and cross-sectional geometries. In one embodiment, a regenerator heat exchanger includes a substantially conically-shaped portion such that the regenerator includes a first section having a larger diameter disposed on the inlet side while having a second section having a relatively smaller diameter at the exit side. This configuration facilitates heat transfer. An elongate or cylindrical body can also be used as a regenerator geometry. Various other geometries for a regenerator can be used. A shield such as a metallic shield can be used to separate the acceptors from the regenerators in one embodiment. A metallic or plastic part can also be used to provide a housing for a coolant. For example, a coolant can be disposed in section E2 of the heat exchanger 90 of Figure 5B.

[0049] The use of one tube design reduces the cost to produce the tube and the cost of assembly. Further, a single tube design can be used across an array of thermodynamic cycle- based machine sizes, further reducing cost. The regenerator heat exchanger, components thereof, and the regenerator material disposed in the applicable canister or tube section can include or be fabricated from various materials, including without limitation, spheres, tubes, foil, anisotropic random fibers, locally isotropic globally anisotropic random fibers, screens (stacked and/or wrapped), meshes (regular, random), mechanically compressed materials (either "locally" as with individual layers, or "globally" as if all the regenerator material is loaded in a canister then compressed into place.), and combinations thereof. In one embodiment, the regenerator material is plurality of fibers having a hexagonal cross-section. The regenerator materials and components of the assemblies described herein can be sintered, welded, brazed, glued, or otherwise processed to position or secure them.

[0050] An thermodynamic cycle-based machine that includes a heat exchanger assembly manufactured using such tubes and using a displacer assembly can be configured for use with power generating devices having a wide range of output powers. For example, the tubular heat exchangers described herein can be used with power generators having an output power that ranges from about 10 W to about 100 kW.

[0051] The variability of pressure loss and temperature changes of the working fluid passing through the regenerators is generally reduced relative to existing regenerator configurations. For example, in one embodiment, pressure losses range from about 0.5 PSI to about 5 PSI. This can result in (1) a substantial improvement in Stirling machine performance, (2) lower machine-to-machine variation and, (3) much lower manufacturing and production cost.

[0052] In one embodiment, the pressure characteristics of each heat exchanger assembly, which can include one or more of a regenerator section, an acceptor section, and a rejector section formed from tubes or canisters and other components, are measured. For example, a pressure drop across the regenerator section or the end ports of a given heat exchanger assembly can be measured. These pressure measurements can be changed by adding or removing regenerator material or otherwise modifying the geometry of the assembly. In one embodiment, a plurality of heat exchanger assemblies with measured pressure drops or other pressure characteristics are arranged to provide balanced flow relative to the containment chamber or with respect to a thermodynamic cycle-based machine in thermal communication with the plurality of heat exchanger assemblies.

[0053] Flow balancing and pressure tuning is facilitated by the position of the tubes and canisters outside of the housing of a thermodynamic cycle-based machine. The use of multiple assemblies allows them to be selectively grouped and/or arranged to promote desirable flow and pressure characteristics based on the individual flow and pressure characteristics of each individual assembly or the components thereof. In one embodiment, uniform flow, balanced flow, aggregate pressure drops, and other properties can be adjusted based on the grouping and arrangement of heat exchange assemblies.

[0054] The aspects, embodiments, features, and examples of the invention are to be considered illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and usages will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0055] The use of headings and sections in the application is not meant to limit the invention; each section can apply to any aspect, embodiment, or feature of the invention.

[0056] Throughout the application, where compositions are described as having, including, or comprising specific components, or where processes are described as having, including or comprising specific process steps, it is contemplated that compositions of the present teachings also consist essentially of, or consist of, the recited components, and that the processes of the present teachings also consist essentially of, or consist of, the recited process steps.

[0057] In the application, where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that the element or component can be any one of the recited elements or components and can be selected from a group consisting of two or more of the recited elements or components. Further, it should be understood that elements and/or features of a composition, an apparatus, or a method described herein can be combined in a variety of ways without departing from the spirit and scope of the present teachings, whether explicit or implicit herein.

[0058] The use of the terms "include," "includes," "including," "have," "has," or "having" should be generally understood as open-ended and non-limiting unless specifically stated otherwise.

[0059] The use of the singular herein includes the plural (and vice versa) unless specifically stated otherwise. Moreover, the singular forms "a," "an," and "the" include plural forms unless the context clearly dictates otherwise. In addition, where the use of the term "about" is before a quantitative value, the present teachings also include the specific quantitative value itself, unless specifically stated otherwise.

[0060] It should be understood that the order of steps or order for performing certain actions is immaterial so long as the present teachings remain operable. Moreover, two or more steps or actions may be conducted simultaneously.

[0061] Where a range or list of values is provided, each intervening value between the upper and lower limits of that range or list of values is individually contemplated and is encompassed within the invention as if each value were specifically enumerated herein. In addition, smaller ranges between and including the upper and lower limits of a given range are contemplated and encompassed within the invention. The listing of exemplary values or ranges is not a disclaimer of other values or ranges between and including the upper and lower limits of a given range.

What is claimed is: