Condenser with a triply periodic minimal surface structure heat exchange core

Abstract

The condenser with a triply periodic minimal surface (TPMS) structure heat exchange core is a moisture condenser for dehumidifiers and the like. The condenser includes a triply periodic minimal surface (TPMS) structure having an inlet side and an outlet side. The TPMS structure includes a plurality of cells, where each of the cells includes wall portions having openings and the plurality of cells define a plurality of flow paths between the inlet side and the outlet side. An inlet conduit is at least partially embedded in the inlet side of the TPMS structure. An outlet conduit is at least partially embedded in the outlet side of the TPMS structure. A heat exchange medium enters the inlet conduit and flows into the plurality of flow paths within the TPMS structure. The heat exchange medium undergoes phase change through heat exchange with the ambient environment and cools the TPMS structure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 779,336, filed on Mar. 28, 2025.BACKGROUNDField

[0002] The disclosure of the present patent application relates to condensers for dehumidifiers, moisture accumulators and the like, and particularly to a condenser having a triply periodic minimal surface (TPMS) structure heat exchange core.Description of Related Art

[0003] Effective management of air humidity is essential for providing a comfortable indoor building environment, as well as meeting a variety of industrial demands. Current dehumidification technologies include ventilation dehumidification, membrane dehumidification, refrigerant dehumidification, and desiccant dehumidification. Among these, refrigerant dehumidification is possibly the most common, making use of a condensation-based dehumidification technology that utilizes a cold source and a heat exchanger (HX) to lower air temperature, causing water vapor in moist air to condense and collect. Due to its broad applicability and high maturity, refrigerant dehumidification is widely adopted in commercial dehumidifiers.

[0004] As a key component of refrigerant dehumidifiers, the air-side condenser plays a vital role in determining dehumidification effectiveness and energy consumption. Most commercial dehumidifiers employ fin-tube condensers designed to maximize heat transfer area though extended fins. Over the past few decades, considerable efforts have been made to enhance the air-side heat transfer in fin-tube condensers, including geometric modification, vortex generator implementation, and surface treatment. Nevertheless, limitations in fin structure design and inadequate condensate removal capabilities associated with dense fin arrays have posed a bottleneck for further enhancements. However, recent advancements in porous biomimetic structures and additive manufacturing (AM) have opened new avenues for developing more efficient and compact condensers.

[0005] Among these porous biomimetic structures, Triply Periodic Minimal Surface (TPMS) structures have emerged as leading candidates for constructing next-generation high-performance HXs. Inspired by natural structures, such as butterfly wing scales and the exoskeleton of the Lamprocyphus augustus weevil, TPMS geometries can be defined through implicit trigonometric equations:ϕ⁢ (2⁢π⁢xL,2⁢π⁢yL,2⁢π⁢zL)=C,where L represents the unit cell length and C represents the curve. Based on the implicit equations, TPMS architectures can be further classified into Diamond, Primitive, F-RD, Gyroid, and Schwarz-D structures, etc. Morphologically, TPMS structures possess inherent porous topologies that have two independent channels, facilitating three-dimensional flow patterns and offering lightweight construction with flexible design possibilities. The smooth, tortuous flow channels within TPMS structures strike an optimal balance between surface area and flow resistance, enhancing heat transfer performance while maintaining affordable pressure drop. Furthermore, advancements in AM technology have enabled the fabrication of various TPMS structures from a range of materials, including ceramic, stainless steel, aluminum alloy, titanium alloy, and copper alloy with unit sizes from millimeters to micrometers.Building upon this foundation, numerous experiments and numerical simulations have demonstrated the superior capabilities of TPMS structures in heat transfer applications. For example, a TPMS HX constructed from copper has been found to provide a heat transfer coefficient which is two times higher than that of a plate HX. Further, TPMS HXs within a supercritical CO2-based Brayton cycle have been found to have heat transfer coefficients that are 15% to 100% higher than those of printed circuit HXs under equivalent pump power conditions.

[0007] While TPMS structures have shown impressive results under dry conditions, several challenges need to be addressed to apply TPMS structures in vapor-liquid phase change scenarios. First, present designs for TPMS HXs are not suitable for dehumidification and water collection applications that necessitate drainage. Second, the advantages of TPMS structures over traditional fin-tube structures in terms of condensation performance have yet to be quantitatively evaluated. Additionally, although the introduction of functional coatings is expected to enhance condensate removal, the integration of TPMS structures with these functional coatings has not yet been attempted. Thus, a condenser with a triply periodic minimal surface structure heat exchange core solving the aforementioned problems is desired.SUMMARY

[0008] The condenser with a triply periodic minimal surface (TPMS) structure heat exchange core is a moisture condenser for dehumidifiers and the like. The condenser includes a triply periodic minimal surface (TPMS) structure having an inlet side and an outlet side. The TPMS structure includes a plurality of cells, where each of the cells includes wall portions having openings and the plurality of cells define a plurality of flow paths between the inlet side and the outlet side. A plurality of air flow channels are further formed through the triply periodic minimal surface structure, with the plurality of air flow channels being separate and sealed from the plurality of flow paths such that there is no mixing between air flowing through the air flow channels and fluid flowing through the flow paths. The TPMS structure may have any suitable type of triply periodic minimal surface. As a non-limiting example, the TPMS may have a gyroid structure. The TPMS structure may be formed from any suitable type of thermally conductive material. As a non-limiting example, the TPMS may be made from AlSi10Mg.

[0009] An inlet conduit is at least partially embedded in the inlet side of the TPMS structure. The inlet conduit has at least one sidewall with a plurality of inlet openings formed therethrough, and the plurality of inlet openings are in fluid communication with the plurality of flow paths. An outlet conduit is at least partially embedded in the outlet side of the TPMS structure, and the outlet conduit has at least one sidewall with a plurality of outlet openings formed therethrough. The plurality of outlet openings are in fluid communication with the plurality of flow paths. Each of the inlet and outlet conduits may have at least a portion shaped as a frustrum of a cone.

[0010] A heat exchange medium, such as a conventional refrigerant or the like, enters the inlet conduit and flows into the plurality of flow paths within the TPMS structure. The heat exchange medium undergoes phase change (e.g., absorbing heat to evaporate from a liquid phase to a gas phase) through heat exchange with the ambient environment and cools the TPMS structure. The heat exchange medium exits the TPMS structure through the outlet conduit.

[0011] These and other features of the present subject matter will become readily apparent upon further review of the following specification.BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 is a front view of a condenser with a triply periodic minimal surface (TPMS) structure heat exchange core.

[0013] FIG. 2 is a top view of the condenser with a triply periodic minimal surface (TPMS) structure heat exchange core.

[0014] FIG. 3 is a side view of the condenser with a triply periodic minimal surface (TPMS) structure heat exchange core.

[0015] FIG. 4 is a front view of an outlet conduit of the condenser with a triply periodic minimal surface (TPMS) structure heat exchange core.

[0016] FIG. 5 is a front view of an inlet conduit of the condenser with a triply periodic minimal surface (TPMS) structure heat exchange core.

[0017] FIG. 6 is a perspective view of a unit cell of the TPMS heat exchange core.

[0018] FIG. 7A is a graph comparing indoor relative humidity (RH) changes over time for the condenser with a triply periodic minimal surface (TPMS) structure heat exchange core compared against a conventional fin-tube condenser.

[0019] FIG. 7B is a graph comparing indoor temperature changes over time for the condenser with a triply periodic minimal surface (TPMS) structure heat exchange core compared against a conventional fin-tube condenser.

[0020] FIG. 8 is a plot comparing volume-based condensate rates and pressure drops per length of the condenser with a triply periodic minimal surface (TPMS) structure heat exchange core, a conventional fin-tube condenser, and a conventional metal foam condenser.

[0021] Similar reference characters denote corresponding features consistently throughout the attached drawings.DETAILED DESCRIPTION

[0022] The condenser with a triply periodic minimal surface (TPMS) structure heat exchange core 10 is a moisture condenser for dehumidifiers, moisture collectors and the like. As shown in FIG. 1, the condenser 10 includes a triply periodic minimal surface (TPMS) structure 12 having an inlet side 32 and an opposed outlet side 34. The TPMS structure 12 includes a plurality of cells, where each of the cells includes wall portions having openings and the plurality of cells define a plurality of flow paths between the inlet side 32 and the outlet side 34. A plurality of air flow channels 42 are further formed through the triply periodic minimal surface structure 12, with the plurality of air flow channels 42 being separate and sealed from the plurality of flow paths such that there is no mixing between air flowing through the air flow channels 42 and fluid flowing through the flow paths. The TPMS structure 12 may have any suitable type of triply periodic minimal surface. As a non-limiting example, the TPMS structure 12 may have a gyroid structure. FIG. 6 illustrates a unit cell 40 of the gyroid structure. The TPMS structure 12 may be formed from any suitable type of thermally conductive material. As a non-limiting example, the TPMS structure 12 may be made from AlSi10Mg.

[0023] As would be recognized by one of ordinary skill in the art, in differential geometry, a triply periodic minimal surface (TPMS) is a minimal surface in three-dimensional space that is invariant under a rank-3 lattice of translations. Such surfaces have the symmetries of a crystallographic group. A gyroid is an infinitely connected triply periodic minimal surface. The gyroid separates space into two oppositely congruent labyrinths of passages. Channels run through the gyroid labyrinths in the (100) and (111) directions, with passages emerging at 70.5° angles to any given channel as it is traversed, with the direction at which they do so gyrating down the channel. In the TPMS structure 12, one labyrinth of passages forms the flow paths (which are internal to the structure shown in FIG. 1) and one labyrinth of passages forms the air flow channels 42. When unit cells 40 (shown in FIG. 6) are joined together to form the overall gyroid structure, they form the two different labyrinth paths which do not intersect, allowing the internal flow passages to carry fluid and be sealed away from the external air flow channels 42, preventing mixing between the air and fluid.

[0024] An inlet conduit 14 is at least partially embedded in the inlet side 32 of the TPMS structure 12. The inlet conduit 14 has at least one sidewall 36 with a plurality of inlet openings 28 formed therethrough, as shown in FIG. 5. The plurality of inlet openings 28 are in fluid communication with the plurality of flow paths in the TPMS structure 12. An outlet conduit 16 is at least partially embedded in the outlet side 34 of the TPMS structure 12, and the outlet conduit 16 has at least one sidewall 38 with a plurality of outlet openings 30 formed therethrough, as shown in FIG. 4. The plurality of outlet openings 30 are in fluid communication with the plurality of flow paths in the TPMS structure 12.

[0025] As best shown in FIGS. 4 and 5, each of the inlet and outlet conduits 14, 16, respectively, may have at least a portion shaped as a frustrum of a cone. Further, inlet conduit 14 has an open end 24 (through which fluid enters) and an opposed closed end 26. Similarly, outlet conduit 16 has an open end 20 (through which the fluid exits) and an opposed closed end 22. As shown, closed end 22 of outlet conduit 16 may have a larger diameter than the open end 20. Closed end 26 of inlet conduit 14, in contrast, may have a diameter which is smaller than the diameter of the open end 24. Although shown as frustoconical, it should be understood that the inlet conduit 14 and outlet conduit 16 may have any suitable shape and relative dimensions. In the non-limiting example of FIGS. 4 and 5, the frustoconical shape is used to enhance flow uniformity and minimize pressure loss.

[0026] A heat exchange medium, such as a conventional refrigerant or the like, enters the inlet conduit 14 through open end 24 and flows into the plurality of flow paths within the TPMS structure 12. The heat exchange medium undergoes phase change (e.g., absorbing heat to evaporate from a liquid phase to a gas phase) through heat exchange with the ambient environment (i.e., the air flowing through air flow channels 42 and across the external surfaces of the TPMS structure 12) and cools the TPMS structure 12. The heat exchange medium exits the TPMS structure 12 through the open end 20 of outlet conduit 16. The cooling of the TPMS structure 12 allows humidity in the air to condense on the surface of TPMS structure 12 for collection as liquid water, similar to the operation of a conventional condenser.

[0027] As shown in FIGS. 2 and 3, the outlet conduit 16 and the inlet conduit 14 may be staggered in the direction of thickness of the TPMS structure 12 (i.e., in the horizontal direction in the orientation of FIG. 3). Although FIGS. 1 and 3 show the inlet and outlet conduits 14, 16 extending through a side panel 18, it should be understood that the side panel 18 may be removed. Giving the TPMS structure 12 some thickness, as illustrated in FIGS. 2 and 3, widens the air flow channels 42, thus increasing the surface area for heat exchange and condensation.

[0028] It should be understood that the TPMS structure 12 may be made from any suitable type of thermally conductive material, and may be manufactured using any suitable type of process. As a non-limiting example, the TPMS structure 12 may be made from AlSi10Mg using selective laser melting technology, and its surface may be polished using magnetic abrasive flow for integration with functional coatings. Functional coatings may include coatings designed to make the external surface of TPMS structure 12 more hydrophobic and / or more slippery in order to enhance the collection of condensate therefrom. As a non-limiting example, liquid chlorine-terminated poly(dimethylsiloxane) (PDMS) may be applied to the untreated TPMS substrate, and the assembly may be placed in a vacuum oven operating at 0.15 Torr with a temperature of 80-100° C. for 60 minutes. Following the reaction, the substrate may then be rinsed in a toluene bath to ensure uniform cleaning and removal of untethered PDMS residues. Finally, the samples may be rinsed with deionized (DI) water and dried with nitrogen gas, resulting in a coated TPMS structure 12.

[0029] The TPMS structure 12 is relatively thin walled, and when made from AlSi10Mg is 14% lighter than conventional wavy-fin tube condensers with the same core volume, thus facilitating easier installation and integration into existing systems. Moreover, the condenser 10 eliminates unnecessary bends and turns in piping and reduces the overall size by 22% compared to conventional fin-tube condensers, which makes it more suitable for space-constrained applications.

[0030] In a wind tunnel test performed under wet conditions, the condensation rate of the TPMS condenser 10 is 35% to 110% higher than that of traditional fin-tube condensers. In a controlled environment of 2 m3, the TPMS condenser 10 was found to regulate temperature and humidity to the comfort zone in half the time when compared to traditional fin-tube condensers, as shown in FIGS. 7A and 7B. FIGS. 7A and 7B illustrate the results of condenser 10 employed as a dehumidifier in a model house of 2 m3, with initial conditions of 27° C. and 70% humidity. FIG. 7A is a graph comparing indoor relative humidity (RH) changes over time for condenser 10 compared against a conventional fin-tube condenser. FIG. 7B is a graph comparing indoor temperature changes over time for condenser 10 compared against a conventional fin-tube condenser. The improvements shown in the graphs are attributed to: 1) enhanced flow mixing, thus facilitating better heat transfer; 2) uniform temperature distribution, thus maintaining a high degree of subcooling and promoting efficient condensation; and 3) effective drainage capabilities, reducing the risk of condensate buildup.

[0031] Compared to condensers made of fin-tubes or metal foam, the TPMS condenser 10 provides greatly improved condensation capability under affordable air pressure loss, as shown in FIG. 8, thus ensuring efficient operation without excessive fan power. FIG. 8 is a plot comparing volume-based condensate rates and pressure drops per length of the TPMS condenser 10, a conventional fin-tube condenser, and a conventional metal foam condenser.

[0032] In use, by replacing traditional fin-tube condensers with the TPMS condenser 10, indoor air can be regulated in a shorter time, thus leading to substantial energy savings and an enhanced comfort experience. It should be understood that the condenser 10 may be used in any suitable application. As a non-limiting example, condenser 10 may be used in atmospheric water harvesting systems. Atmospheric water harvesting systems are designed to address water scarcity, particularly in regions where traditional water sources are limited or contaminated. Like dehumidification process, the water harvesting process begins by gathering air using fans or utilizing natural airflow. The collected air is then processed using passive cooling techniques to promote water droplet formation and collection. Due to its superior condensation capability and efficient drainage performance, condenser 10 can also be employed as a water harvesting system to provide a sustainable water source.

[0033] It is to be understood that the condenser with a triply periodic minimal surface structure heat exchange core is not limited to the specific embodiments described above, but encompasses any and all embodiments within the scope of the generic language of the following claims enabled by the embodiments described herein, or otherwise shown in the drawings or described above in terms sufficient to enable one of ordinary skill in the art to make and use the claimed subject matter.

Claims

1. A condenser with a triply periodic minimal surface structure heat exchange core, comprising:a triply periodic minimal surface structure having an inlet side and an outlet side, the triply periodic minimal surface structure comprising a plurality of cells, wherein each of the cells includes wall portions having openings, and wherein the plurality of cells define a plurality of flow paths between the inlet side and the outlet side;an inlet conduit at least partially embedded in the inlet side of the triply periodic minimal surface structure, the inlet conduit having at least one sidewall with a plurality of inlet openings formed therethrough, wherein the plurality of inlet openings are in fluid communication with the plurality of flow paths;an outlet conduit at least partially embedded in the outlet side of the triply periodic minimal surface structure, the outlet conduit having at least one sidewall with a plurality of outlet openings formed therethrough, wherein the plurality of outlet openings are in fluid communication with the plurality of flow paths; anda heat exchange medium, wherein the heat exchange medium enters the inlet conduit and flows into the plurality of flow paths within the triply periodic minimal surface structure, the heat exchange medium undergoing phase change through heat exchange with an ambient environment and cooling the triply periodic minimal surface structure, the heat exchange medium exiting the triply periodic minimal surface structure through the outlet conduit.

2. The condenser with a triply periodic minimal surface structure heat exchange core as recited in claim 1, wherein the triply periodic minimal surface structure defines a plurality of air flow channels.

3. The condenser with a triply periodic minimal surface structure heat exchange core as recited in claim 1, wherein the triply periodic minimal surface structure has a gyroid structure.

4. The condenser with a triply periodic minimal surface structure heat exchange core as recited in claim 1, wherein each of the inlet and outlet conduits has at least a portion shaped as a frustrum of a cone.

5. The condenser with a triply periodic minimal surface structure heat exchange core as recited in claim 4, wherein each of the inlet and outlet conduits has an open end and an opposed closed end.

6. The condenser with a triply periodic minimal surface structure heat exchange core as recited in claim 5, wherein the closed end of the inlet conduit has a diameter which is smaller than a diameter of the open end of the inlet conduit.

7. The condenser with a triply periodic minimal surface structure heat exchange core as recited in claim 6, wherein the closed end of the outlet conduit has a diameter which is larger than a diameter of the open end of the outlet conduit.

8. The condenser with a triply periodic minimal surface structure heat exchange core as recited in claim 1, wherein the triply periodic minimal surface comprises AlSi10Mg.

9. The condenser with a triply periodic minimal surface structure heat exchange core as recited in claim 8, wherein the triply periodic minimal surface is coated with polydimethylsiloxane.

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