TWM651356U - Triply periodic minimal surface structure heat exchangers with equal or different characteristic diameters - Google Patents

Abstract

A Triply Periodic Minimal Surface (TPMS) structure is utilized and designed in one-piece new structure of heat exchanger. This new TPMS structure heat exchanger main body is composed of a hot flow inlet, a hot flow exit, a cold flow inlet, a cold flow exit, and a TPMS structure forming two independent channels to allow these two fluid flow in a 3D corrugated structure channel without mixing together. Because of its complex geometry, it is made by either additive manufacturing technique or lost wax technique successfully. Therefore, this structure can be applied as a heat exchanger to enhance the heat transfer efficiency.

The heat transfer coefficient, fluid contact area and temperature difference are the most important factors for the heat exchanger rate; The TPMS structure can be controlled by the characteristic diameter of the two fluid pipelines, and by adjusting the same or two different characteristic diameters, the relative space volume and surface are of the two fluids can be adjusted, that is the new strategy for the efficiency of the heat exchanger to be further improved.

As the surface-to-volume ratio is increased by more than 2-3 times based on the TPMS structure, and due to its good structural characteristics, it is possible to design a relatively thinner tube thickness, minimized material to weight ratio and high strength-to-weight ratio, so the efficiency of the heat exchanger is greatly improved. Due to the inherent structural strengthening properties, the pressure (at the same temperature) that can be tolerated is much higher than that of traditional heat exchangers, while maintaining low weight and smaller volume.

According to the design requirements, the heat exchanger can define different shells and adopt different TPMS structures. Among all TPMS structures, five TPMS structures can be utilized for heat exchanger, names are Gyroid, Schwarz Primitive, Diamond, Lidinoid, and Split-P. For example, gyroid has two coupling volumes separated by Gyroid wall, that two coupling gyroid can be utilize for heat exchanger with closing the unwanted holes. This innovative design adopts the design method based on 3D printing, in which the hot flow channel and the cold flow channel may not be on the same plane to form a design with a 90-degree, and one of the flow channels can also be further designed by two intersecting 90 degrees. It can be matched with the angle of special needs to achieve a highly flexible three-dimensional import and export orientation design, which is conducive to the deployment and full use of space.

Description

Three-dimensional minimal surface (TPMS) structural heat exchanger

Heat exchanger is a system used to transfer heat between two or more fluids. Heat exchangers are used for cooling and heating processes. For example, the radiator of a car engine is a heat exchanger. The design of this heat exchanger is based on the radiator pipeline structure in which the refrigerant circulates through the surroundings of the engine and is heated and then flows to the water tank. Heat exchange, the air flows through the radiator structure to discharge the engine waste heat into the atmosphere. The fluids can be separated by solid walls to prevent mixing, or they can be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power stations, chemical plants, petrochemical plants, refineries, natural gas processing and wastewater treatment.

Three-dimensional Periodic Minimal Surface (TPMS) represents a periodic infinite structure with three independent directions and a surface with an average curvature of zero. The three-dimensional periodic minimal surface (TPMS) structure is a biomimetic structure that has many advantages in engineering and biomedicine. From the perspective of recreating itself in 3D, a minimal surface has a continuous average curvature of zero, i.e. the sum of the principal curvatures at each point is zero. So far, many TPMS structures have been discovered and studied, most of which are in the field of structure, and other fields have just begun. This patent is based on the research of applying TPMS structure to heat exchangers.

The name Additive Manufacturing, or 3D Printing, means the manufacturing process of depositing layer by layer by adding materials as a continuous material; it is also called 3D column (printing) and is synonymous with additive manufacturing.

Additive manufacturing is the construction of 3D objects from computer drawing models (CAD) or digital 3D models (Object). The term "3D printing" can refer to various processes in which materials are deposited, joined, or solidified under computer control to create a 3D object, in which materials are added together (such as plastic, liquid, or powder particles fused together), usually in a layer The result of sequential processing of one layer.

The history of heat exchanger (HEX) can be traced back to the 1880s, and its main application is in the food and beverage industry. It is generally accepted that the first recorded patent for a plate heat exchanger was granted to Albrecht Dracke of Germany in 1878. However, the first modern and commercial examples of heat exchangers can be found in the early 1900s. The classic example of a heat exchanger is found in internal combustion engines, where a circulating fluid called the engine refrigerant flows through the radiator pipe structure, exchanging heat with the air flowing through the radiator pipe, cooling the refrigerant and transferring heat to the incoming air.

Another example is a heat sink, which is a passive heat exchanger that transfers heat generated by electronic or mechanical equipment to a fluid medium, usually air or a liquid coolant.

Heat exchangers impact the overall efficiency of the plant, and as industry grows, the need for more efficient and improved heat exchangers continues to increase. Heat exchanger design has continued to improve over the centuries. There are different types of heat exchangers, such as Shell & Tube, Plate, Plate & Frame, Plate & Shell and other types of heat exchangers. Plate and frame heat exchangers have been widely used in the past due to their ease of maintenance and high efficiency. But the basic design philosophy is the same for all types of heat exchangers.

Plate Heat Exchanger (PHE) is a heat exchanger that uses metal plates to transfer heat between two fluids. It consists of a series of thin plates, two types of thin plates are staggered on a frame, and the space between each adjacent staggered plate is exposed to the same fluid. Plate heat exchangers have a major advantage over traditional heat exchangers in that the fluid flows spread out over the plates, so the fluid is exposed to a larger surface area. These sheets have corrugated flow channels, which increase strength and help promote turbulent flow. To obtain the correct liquid velocity degree and appropriate pressure drop, thin plates can be placed in a series of channels.

So far, three-dimensional periodic minimal surfaces (TPMS) have discovered and are studying a variety of TPMS structures. The surface described by Schwarz in 1865 was the first example of TPMS, along with the surface described by his colleague Neovius in 1883. Alan Schoen (American NASA scientist) described another 12 TPMS in 1970. As a lightweight material, TPMS is widely used. In addition to structure, it breaks limitations and can also be used in many fields, such as sound absorption, battery electrodes, catalyst carriers and other technical fields.

Three-dimensional minimal surface structure heat exchanger

The triple periodic (i.e. repeated extension in three-dimensional direction) minimum curved surface (TPMS) structure (similar to a honeycomb structure) has a special feature - that is, there are a pair (two sets) of 3D infinitely extending pipes that are not connected to each other. Therefore, its non-connected characteristics can be used to transform it into an innovative three-dimensional minimally curved structure heat exchanger (TPMS Heat Exchanger) to prevent hot fluid and cold fluid from mixing together. The main feature of this creation is to apply the TPMS structure to the new field of heat exchangers. This innovative structure can be used in heat exchangers and thermal management equipment to achieve more efficient heat transfer phenomena.

Compared with plate heat exchangers, this creation "Three-dimensional Minimum Curved Surface (TPMS) Structure Heat Exchanger" has many advantages as follows:

(1) Because of the high structural strength characteristics of TPMS, it can withstand higher pressure than traditional heat exchangers at the same temperature.

(2) Because of the highly curved surface characteristics of TPMS, its contact surface area is approximately twice the original area of a general plate heat exchanger;

(3) Due to the highly curved surface characteristics of TPMS, the fluid is more likely to generate turbulence when flowing at the base, which prevents the fluid from producing boundary layer growth (Boundary Layer Growth) in the flat flow. The heat transfer coefficient decreases with the length, reducing the overall heat transfer. efficiency. That is, TPMS heat exchangers can have higher heat transfer coefficient.

(4) Due to the high structural strength of TPMS, under the same operating pressure requirements, the overall tube wall can be designed to be thinner, which can reduce the thermal resistance (Thermal Resistance) and thus achieve greater heat transfer efficiency.

From the above four points, the outstanding characteristics of the three-dimensional minimum curved structure heat exchanger (TPMS Heat Exchanger) of this creation can be more clearly demonstrated. It will have a heat transfer efficiency nearly five times more than the so-called advanced plate heat exchangers in the past. , there is an opportunity to significantly replace devices with high heat transfer efficiency or high heat transfer capacity in the future.

However, TPMS heat exchanger, an innovative heat exchanger concept structure, can currently only be realized through additive manufacturing technology. For example, the Gyroid heat exchanger has two coupling bodies separated by structural walls. The two cross structures can be used by closing unnecessary holes to achieve the use of the heat exchanger. These complex heat exchanger structures can currently be achieved using additive manufacturing methods. .

This new creation is a new TPMS heat exchanger as shown in Figure 1. This three-dimensional periodic minimum surface (TPMS) structure includes a hot fluid inlet and a hot fluid outlet and a cold fluid inlet and a cold fluid outlet. This The TPMS structure of the two fluids inside the heat exchanger happens to be different flow channels that intersect with each other in 3D but are independent and do not mix with each other. Therefore, the conditions are met for the heat exchanger to achieve heat transfer only through the tube wall. The fluid contact area, heat transfer coefficient and temperature difference (Temperature Difference) are the most important factors for heat exchanger efficiency. The following is the governing equation (1) describing the phenomenon of fluid convection heat transfer: q = h _c . A． △T (1)

Among them, q is the heat transfer amount per unit time (W/hr) ; A is the heat transfer surface area ( m ² ) , △T is the temperature difference between the heat transfer surface and the fluid (℃) ; h _c is the convection heat transfer coefficient ( W/ m ² ℃).

Based on the above calculation of convective heat transfer, it is estimated that for a heat exchanger with approximately the same volume, the new TPMS heat exchanger created by this invention increases the surface area by about 2-3 times, and the heat transfer coefficient is based on the turbulent flow (Turbulent flow) flow field instead of laminar flow (Laminar Flow) can increase the flow field by about 2-3 times. In addition, the thickness can be reduced to reduce thermal resistance and other benefits. Therefore, the newly created heat exchanger will be about 5-10 times more efficient. The heat transfer gain or efficiency is increased.

This new creation emphasizes that based on the TPMS structure, the characteristic diameters (Characteristic Diameter, d _c ) of the two fluid pipelines can be adjusted to be the same ( d _C1 = d _C2 ) or different ( d _C1 ≠ d _C2 ). By adjusting the relative space size of the two fluids, the efficiency of the heat exchanger can be further improved; generally, TPMS can increase the surface-to-volume ratio by more than 2-3 times compared to plate heat exchangers at the same diameter, and due to its excellent structural characteristics, it can be designed The relatively thinner tube wall thickness, minimized material weight, and high strength-to-weight ratio significantly improve the efficiency of the heat exchanger.

Due to the innate structural strengthening characteristics, the pressure it can withstand (at the same temperature) is much higher than that of traditional heat exchangers, while maintaining low weight and smaller volume. The heat exchanger can define different shells and adopt different TPMS structures according to the design requirements. Among all TPMS structures, there are 5 TPMS structures that can be used in heat exchangers, namely porous spiral surface (Gyroid) structure, Schwarz Primitive structure, diamond structure, and Lidinoid structure. There are five structures in total including Split-P structure.

100 : Main body of heat exchanger

101 :Inlet of hot fluid

102 : Exit of hot fluid

103 :Inlet of cold fluid

104 : Exit of cold fluid

105 : Inlet chamber of hot fluid

106 : Exit chamber of hot fluid

107 :Inlet chamber of cold fluid

108 : Exit chamber of cold fluid

110 : TPMS structure in heat exchanger

111 : Inlet passages of hot fluid

112 : Exit passages of hot fluid

113 : Inlet passages of cold fluid

114 : Exit passages of cold fluid

201 : Blockage plate in hot flow inlet (Blockage plate in hot flow inlet)

202 : Blockage plate in hot flow exit hole (Blockage plate in hot flow exit)

203 : Blockage plate in cold flow inlet (Blockage plate in cold flow inlet)

204 :Blockage plate in cold flow exit (Blockage plate in cold flow exit)

300 : Transition section from rectangle to circle

301 : Pipe connector

302 : Transition section from rectangle to circle with inclination angle

Figure 1. A schematic cross-sectional view of a Gyroid (a type of three-dimensional minimally curved structure) heat exchanger.

Figure 2. The two characteristic diameters of the Gyroid structure heat exchanger can be the same or different. (a) The picture shows the structural type of the two characteristic diameters with the same diameter ( d _C1 = d _C2 ). (b) The picture shows the two characteristics. Structural types with different diameters ( d _C1 ≠d _C2 ).

Figure 3. It represents the operation of the heat exchanger of the Gyroid structure. The hot and cold fluids entering the heat exchanger can be in opposite directions, as shown in Figure 3(a), or in the same direction, as shown in Figure 3(b).

Figure 4. The Gyroid structure is one of the TPMS structures that can be used in heat exchangers.

Figure 5. Schwarz Primitive structure, the second TPMS structure that can be used in heat exchangers.

Figure 6. The third Diamond structure that can be used in TPMS structures for heat exchangers.

Figure 7. The fourth Lidinoid structure that can be used in heat exchanger TPMS structures.

Figure 8. Split-P structure, the fifth TPMS structure that can be used in heat exchangers.

Figure 9. The Gyroid structure of the heat exchanger TPMS structure closes unnecessary holes to form two coupling spaces separated by structural walls. Figure 9(a) is the appearance of the Gyroid heat exchanger structure; Figure 9(b) is an independent drawing of the position and structure of the four-sided orifice plugging plates.

Figure 10. An example of TPMS being applied to two different hole characteristic diameters in the fluid flow within the main structure of the heat exchanger, as well as an oblique tapered adapter pipe with different inlet and outlet shapes at both ends.

Figure 11. An example of two pairs of cylindrical connecting tubes that can directly connect the inlet and outlet of hot fluid and cold fluid with two different hole characteristic diameters in the fluid flow in the main structure of the TPMS structure (Gyroid) heat exchanger.

Figure 12. The main structure of the Gyroid heat exchanger has an inclined tapered transfer tube with two ends with different inlet and outlet shapes and vertical directions, as shown in Figure 12(a), and a cylindrical structure (Gyroid) with two different hole characteristic diameters inside. The top view of the heat exchanger is shown in Figure 12(b).

Refer to Figure 1, which is a schematic cross-sectional view of the Gyroid heat exchanger structure. The design of the Gyroid minimum curved structure heat exchanger is similar to the external geometry of the traditional heat exchanger, but the internal structure is different. The main heat exchanger structure is changed to an innovative TPMS structure. body. The heat exchanger main structure 100 is a space covered by a Gyroid heat exchanger structure 110 and a main structure shell 109 inside. The heat exchanger main structure has two inlets and two outlet channels, which are the thermal fluid inlets 101. , hot fluid outlet 102 , cold fluid inlet 103 and cold fluid outlet 104 . The characteristic diameters of the two fluid holes in the TPMS structure (Gyroid) are basically the same. In the operation of the heat exchanger, the fluid entering from the hot fluid inlet 101 first reaches a hot fluid inlet buffer chamber 105 and passes through the hot fluid inlet channel 111 in the TPMS structure. Here, the cold flow channel adjacent to the TPMS structure passes through the tube wall. After heat exchange, it flows diagonally into the hot fluid outlet channel 112 , then flows to the hot fluid outlet buffer chamber 106 , and finally flows out of the heat exchanger from the hot fluid outlet 102 ; the cold fluid flows in a similar way from the cold fluid outlet to the hot fluid outlet buffer chamber 106. The fluid entering the inlet 103 first reaches a cold fluid inlet buffer chamber 107 , passes through the cold fluid inlet channel 113 in the TPMS structure, and is adjacent to the hot flow channel in the TPMS structure. After heat exchange through the tube wall, it then flows in in the diagonal direction. The cold fluid outlet channel 114 then flows to the cold fluid outlet buffer chamber 108 , and finally flows out of the heat exchanger through the cold fluid outlet 104 ; the TPMS structure of the two fluids inside the heat exchanger happens to be different flow channels that form a 3D relationship with each other. They are staggered but independent and do not mix with each other, so the heat exchanger can achieve heat transfer conditions only through the tube wall. These two separated coupling bodies, that is, two coupling structures, can be used in the heat exchanger structure, but unnecessary holes need to be closed; Figure 9(a) shows the Gyroid heat exchanger structure 110 Appearance, in order to control a three-dimensional connected channel within a certain range and operate according to the inlet and outlet needs of the heat exchanger, it is necessary to close the plugging plate 201 of the inlet hole in the direction of hot fluid , and the plugging plate 201 of the outlet hole in the direction of hot fluid. 202 , as well as the plugging plate 203 for closing the inlet hole in the direction of the cold fluid , and the plugging plate 204 for the outlet hole in the direction of the cold fluid; Figure 9(b) shows the position and structure of the four-sided plugging plates independently drawn. The four closed The plugging plate on the surface of the heat exchanger allows the heat exchanger to conduct the flow of hot fluid and cold fluid without causing them to mix with each other internally. The completely isolated flow path can only pass through the adjacent walls. The phenomenon of heat transfer is the necessary condition for the above-mentioned heat exchanger.

Figure 10 is an isometric cross-sectional view of a TPMS heat exchanger. It is a minimum curved surface heat exchanger with a square design structure (Gyroid), as shown in Figure 2. Another feature of this new creation is that the Gyroid structure can be used according to actual heat dissipation needs. During engineering design, the area size of the two independent flow channels is adjusted. The area size can be determined by the two characteristic diameters (Characteristic Diameter) d _C1 and d _C2 that form the Gyroid structure. When d _C1 = d _C2 , as shown in Figure 2(a) ), the areas of the two independent flow channels are the same; when d _C1 ≠ d _C2 , as shown in Figure 2(b), two independent but different-sized flow channel spaces can be formed, which is conducive to different flow requirements. Or the needs of different fluids (such as different liquid and gas flow channels). The two-phase coexistence heat exchanger can use two mixing volumes of different sizes. It is also clearly seen from the figure that one of the flow channels has a larger flow channel space with a large characteristic diameter d _C1 . On the contrary, the other flow channel has a small flow channel. The characteristic diameter d _C2 has a smaller flow channel space. This embodiment is also installed in the main structure of the heat exchanger, but the characteristic diameters of two different holes in the diagonal fluid flow ( d _C1 ≠ d _C2 ) are shown in Figure 2(b). The cross-sectional shape of the structure body is It is a rectangular body, and the two pairs of cold flow fluids are circular tubes, so the two ends are connected to circular transition sections 300 with rectangular shapes of different shapes. The two pairs of connecting pipes 301 can connect the inlet and outlet of the hot fluid and the cold fluid respectively. Like a general shell and tube heat exchanger, the hot and cold fluids entering the heat exchanger can be in the opposite direction (Counter Flow), as shown in Figure 3(a), or in the same direction (Parallel Flow), as shown in Figure 3 (b) is shown. The heat exchange efficiencies of these two heat exchanger operating modes are different, and different operating modes can be set according to actual needs.

Figure 11 is an isometric cross-sectional view of another embodiment of a TPMS structure (Gyroid) heat exchanger. Its appearance has a square design heat exchanger main structure , and its interior is the same as a structure (Gyroid) minimum curved surface structure heat exchanger. The device In the main structure of the heat exchanger, two different hole characteristic diameters ( d _C1 ≠d _C2 ) are provided in the diagonal fluid flow. The cross-sectional shape is shown in Figure 2(b). The two pairs of connecting circular tubes 301 can be directly connected. Before adopting the stacked manufacturing method to connect the inlet and outlet of the hot fluid and the cold fluid, the connecting section can be designed to reduce the number of square to round transition sections to save space.

Figure 12 is an embodiment of the main structure design of the Gyroid heat exchanger that is different from the traditional heat exchanger pipe connection. It has two fluid inlet and outlet directions and two directions on mutually perpendicular planes with an inclined rectangular to a circular shape. The transfer section 302 and the rectangular transfer section 300 are connected to a circular shape. The appearance of the main structure is a three-dimensional view as shown in Figure 12(a). The inside of the main structure is a cylindrical structure (Gyroid) heat exchanger with two different hole characteristic diameters. The top view of the internal structure of the device is shown in Figure 12(b). This embodiment further demonstrates the design method based on the use of 3D printing, in which the hot flow channel and the cold flow channel are not on the same plane, forming a vertical intersection design of 90 degrees, and one of the flow channels can also be further composed of two vertical intersections of 90 degrees. This is a design structure that meets special needs and can achieve highly flexible three-dimensional entrance and exit directions, which helps with space deployment and maximizes the use of corner space.

100 : Main body of heat exchanger

101 :Inlet of hot fluid

102 : Exit of hot fluid

103 :Inlet of cold fluid

104 : Exit of cold fluid

105 : Inlet chamber of hot fluid

106 : Exit chamber of hot fluid

107 :Inlet chamber of cold fluid

108 : Exit chamber of cold fluid

109 : Outer shell of main body of heat exchanger

110 : TPMS structure in heat exchanger

111 : Inlet passages of hot fluid

112 : Exit passages of hot fluid

113 : Inlet passages of cold fluid

114 : Exit passages of cold fluid

Claims (6)

A three-dimensional minimum curved surface (TPMS) structure heat exchanger, whose integrated structural features include: a heat exchanger main structure, a hot fluid inlet and a hot fluid outlet, a cold fluid inlet and a cold fluid outlet, and an internal three-dimensional Minimum curved surface (TPMS) structural heat exchanger. The TPMS structural heat exchanger is divided into two independent volume spaces, which can provide channels for the inflow and outflow of cold fluid and hot fluid respectively. The two sets of fluid channels in this TPMS structural space are 3D interlaced. , the two are separated by 3D continuous walls and prevent mixing. These two independent volume spaces form a special TPMS structure heat exchanger. During operation, the cold fluid enters the buffer chamber from the cold fluid inlet, and then flows into the cold fluid of the TPMS structure heat exchanger. The hot fluid enters the buffer chamber through the hot fluid inlet, and then flows into the hot fluid volume space of the TPMS structure heat exchanger to meet the needs of customers. The two volume spaces can be the same or different fluids, in phase (Phase) or out of phase. The requirements for fluids at different temperatures operate similar to traditional parallel flow or counter flow heat exchangers. The three-dimensional minimum curved surface (TPMS) structure heat exchanger described in item 1 of the patent application is generally characterized by a TPMS structure with two identical fluid volume spaces, that is, the channel characteristic diameters of the cold fluid volume and the hot fluid volume are the same. , but the design may not be limited to the design of the same channel characteristic diameter due to the difference in flow rate between the two fluids, that is, the channel characteristic diameters of the cold fluid volume and the hot fluid volume are the same or different, that is, the space sizes of the two fluid volumes can be the same or different. . The three-dimensional minimal surface (TPMS) structure heat exchanger described in item 1 of the patent application scope can have a porous spiral surface (Gyroid) structure, a Schwarz primitive structure, or a diamond-shaped heat exchanger. It consists of five three-dimensional infinite extension structures: Lidinoid structure and Split-P structure. Its channel hole shapes can include square, spherical and cylindrical, etc., which are the main surface locations for heat transfer. A three-dimensional minimum curved surface (TPMS) structural heat exchanger as described in item 1 of the patent application, wherein the TPMS structure is made of additive manufacturing (AM), but is not limited to AM manufacturing processes, and some other manufacturing processes, such as lost foam Casting process, polymer casting (Polycast) process, lost wax casting three processes, TPMS structural parts can also be provided. For example, in the three-dimensional minimum curved surface (TPMS) structure heat exchanger described in item 1 of the patent application, its relative position, fluid inlet and outlet, and flow direction can be easily changed according to needs. The design features that can be included are cold fluid volume flow and hot fluid volume flow. They can be designed with the same flow direction (Parallel Flow), cross flow direction (Intersection Flow) and opposite flow direction (Counter Flow). For example, the three-dimensional minimum curved surface (TPMS) structural heat exchanger described in item 1 of the patent application can be manufactured using a design method based on 3D printing, in which the hot flow channel and the cold flow channel may not be on the same plane and may intersect. A 90-degree design or any other angle, and one of the flow channels can also be further made up of two crossed 90-degree designs or any other angle. It can meet special needs to achieve a highly flexible three-dimensional entrance and exit orientation design, which contributes to space preparation and full use.