EP4600599A1

EP4600599A1 - A fin having elliptical collar bases and airfoils and related fin-and-tube heat exchanger

Info

Publication number: EP4600599A1
Application number: EP25156909.1A
Authority: EP
Inventors: Kui XIA; Zi Xia Jin; Bin Bin CHEN; Jian Jun YUE; Yves Jacques Raimbault
Original assignee: Trane Air Conditioning Systems China Co Ltd; Trane International Inc
Current assignee: Trane Air Conditioning Systems China Co Ltd; Trane International Inc
Priority date: 2024-02-09
Filing date: 2025-02-10
Publication date: 2025-08-13
Also published as: US20250257955A1; CN120467050A

Abstract

A fin-and-tube heat exchanger and a fin are disclosed. The fin includes a corrugated plate having a first side and a second side opposing the first side, the corrugated plate having a plurality of alternative peaks and valleys relative to the first side of the corrugated plate; one of a plurality of elliptical collar bases protruding from the first side of the corrugated plate; and a first airfoil and a second airfoil extending between a major axis and a minor axis of, and curving around, the one of the plurality of elliptical collar bases. The first airfoil is disposed in a first quadrant for the one of the plurality of elliptical collar bases. The second airfoil is disposed in a second quadrant for the one of the plurality of elliptical collar bases, the second quadrant is adjacent to the first quadrant at the major axis.

Description

FIELD

This disclosure relates to fins of a heat exchanger for refrigerant circuits for a heating, ventilation, air conditioning, and refrigeration ("HVACR") system. More particularly, this disclosure relates to fins having elliptical collar bases and airfoils for, when a fluid crossflows the heat transfer tubes at the elliptical collar bases, reducing an area of fluid stagnation due to wake detachment in the trailing area behind of the heat transfer tubes that extend through the fins.

BACKGROUND

Heating, ventilation, air conditioning, and refrigeration ("HVACR") systems are generally used to heat, cool, and/or ventilate an enclosed space (e.g., an interior space of a commercial building or a residential building, an interior space of a refrigerated transport unit, or the like). An HVACR system may include a refrigerant circuit for providing cooled or heated air to the area. The refrigerant circuit utilizes a working fluid containing refrigerant to cool or heat a process fluid (e.g., air) directly or indirectly. A heat exchanger can be used to facilitate the heat exchange between the working fluid and the process fluid. The heat exchanger can have a plurality of fins. The process fluid can flow between the fins to exchange thermal energy with the working fluid via the fins and the heat transfer tubes.

SUMMARY

This disclosure relates to fins of a heat exchanger for refrigerant circuits for a heating, ventilation, air conditioning, and refrigeration ("HVACR") system. More particularly, this disclosure relates to fins having elliptical collar bases and airfoils for, when a fluid crossflows the heat transfer tubes at the elliptical collar bases, reducing an area of fluid stagnation due to wake detachment in the trailing area behind of the heat transfer tubes that extend through the fins.
In an embodiment, a fin includes a corrugated plate having a first side and a second side opposing the first side, the corrugated plate having a plurality of folds that are alternative peaks and valleys relative to the first side of the corrugated plate; one of a plurality of elliptical collar bases protruding from the first side of the corrugated plate; and a first airfoil and a second airfoil extending between a major axis and a minor axis of, and curving around, the one of the plurality of elliptical collar bases. The first airfoil is disposed in a first quadrant for the one of the plurality of elliptical collar bases, and the second airfoil is disposed in a second quadrant for the one of the plurality of elliptical collar bases, the second quadrant is adjacent to the first quadrant at the major axis.
In an embodiment, the one of the plurality of elliptical collar bases embosses into the second side and protrudes from the first side over one of the peaks.
In an embodiment, the one of the plurality of elliptical collar bases extends across three adjacent folds on the corrugated plate and within five adjacent folds on the corrugated plate.
In an embodiment, a transitioning side connects the one of the plurality of elliptical collar bases to the corrugated plate.
In an embodiment, the transitioning side wedges outwardly from the one of the plurality of elliptical collar bases to the first side of the corrugated plate.
In an embodiment, the one of the plurality of elliptical collar bases is centered over one of the peaks.
In an embodiment, the one of the plurality of elliptical collar bases is flush with the one of the peaks.
In an embodiment, the one of the airfoils extends across one of the valleys in a trailing area of the one of the plurality of elliptical collar bases.
In an embodiment, the one of the airfoils has a trailing end extended toward the major axis of the one of the plurality of elliptical collar bases, and a leading end extended toward the minor axis of the one of the plurality of elliptical collar bases.
In an embodiment, a leading end of the one of the airfoils is disposed further away from the one of the plurality of elliptical collar bases (e.g., relative to an outer edge of the one of the plurality of elliptical collars) than a trailing end of the first airfoil.
In an embodiment, the one of the airfoils is extended within three adjacent folds of the corrugated plate.
In an embodiment, the one of the airfoils embosses into the first side and protrudes from the second side of the corrugated plate.
In an embodiment, the fin includes a rippled edge.
In an embodiment, a plurality of heat transfer tubes extends through a plurality of fins. One of the plurality of fins includes a corrugated plate having a first side and a second side opposing the first side. The corrugated plate has a plurality of alternative peaks and valleys relative to the first side of the corrugated plate. One of a plurality of elliptical collar bases protrudes from the first side of the corrugated plate. A first airfoil and a second airfoil extend between a major axis and a minor axis of, and curving around, the one of the plurality of elliptical collar bases. The first airfoil is disposed in a first quadrant for the one of the plurality of elliptical collar bases, and the second airfoil is disposed in a second quadrant for the one of the plurality of elliptical collar bases. The second quadrant is adjacent to the first quadrant at the major axis.
In an embodiment, the one of the plurality of elliptical collar bases embosses into the second side and protrudes from the first side over one of the peaks, and the one of the airfoils embosses into the first side and protrudes from the second side of the corrugated plate.
In an embodiment, the one of the plurality of fins includes a fin collar connected to the one of the plurality of elliptical collar bases, and an external surface of one of the heat transfer tubes is contacted with the fin collar.
In an embodiment, the one of the airfoils extends across one of the valleys in a trailing area of the one of the plurality of elliptical collar bases, and a leading end of the one of the airfoils is disposed further away from the one of the plurality of elliptical collar bases than a trailing end of the first airfoil.
In an embodiment, a transitioning side connects the one of the plurality of elliptical collar bases to the corrugated plate, and the transitioning side wedges outwardly from the one of the plurality of elliptical collar bases to the first side of the corrugated plate.
In an embodiment, the one of the plurality of elliptical collar bases is centered over one of the peaks, and the one of the plurality of elliptical collar bases is flush with the one of the peaks.
In an embodiment, the one of the plurality of fins has a leading edge and a trailing edge, and a rippled edge is disposed on one or both of the leading edge and the trailing edge.
By including the elliptical collar bases and airfoils on the fins according to the embodiments of the present application, the fluid-side heat transfer coefficient (e.g., the air-side heat transfer coefficient, or the like) of a fin can be improved (e.g., compared to comparative fins having the same tube diameter, face pitch, row pitch, and/or the like) by more than 5%, while increasing the pressure drop across the fin by a small percentage, which is generally overweighed by the gain in the heat transfer coefficient. It is appreciated that, pressure drop can be the pressure drop of a fluid (e.g., air) when the fluid flows through a fin-and-tube heat exchanger and exchanges heat with the refrigerant inside the tube. It is appreciated that, in an embodiment, the fluid-side heat transfer coefficient can be air-side heat transfer coefficient of a fin of a heat exchanger, and the heat exchanger can be a fin-and-tube heat exchanger.
The improvements to the fluid-side heat transfer coefficient of a fin (e.g., to the air-side heat transfer coefficient or the like) according the present disclosure can be at least partially attributed to reduce boundary layer thickness and increase turbulence in the fluid flowing between the fins and/or the heat transfer tubes of a fin-and-tube heat exchanger. In some embodiments, when the fluid flows through the heat exchanger, the fluid flows across heat transfer tubes and separates at a location forming wake detachment in the trailing area that is behind the respective tubes relative to the flow direction of the fluid (e.g., the air flowing across the heat transfer tubes and/or between the fins). In the area of wake detachment, the fluid stagnates and limits the capacity of heat transfer. The fins of the present disclosure reduce the stagnation zone in the trailing areas, thereby improving the heat transfer for the fins.
Rippled edges on the fins, and/or the shape and size of the elliptical collar bases, can improve the stiffness of the fin according to the embodiments of the present disclosure (e.g., by optimizing elliptical collar base dimension, an angle between the collar base and the corrugated plate of the fins, and/or the like). For example, a fin having a face pitch (e.g., 22 mm) and row pitch (e.g., 19.05 mm) for receiving 7 mm heat transfer tubes, and three rows of fin collars for receiving heat transfer tubes and large elliptical collar base dimension may have a maximum deformation of at or about 5.2 millimeter (mm) and a maximum stress of at or about 28.5 mega-Pascal (MPa) under condition A and a maximum deformation of at or about 254.7 mm and a maximum stress of at or about 222.5 MPa under condition B. By including the elliptical collar base (which may have a predetermined dimension) with three rows of opening for receiving the heat transfer tubes, the maximum deformation could reduce to at or about 4.9 mm and the maximum stress could reduce to at or about 27.5 MPa under condition A and a maximum deformation of at or about 176.1 mm and a maximum stress of at or about 139.2 MPa under condition B. It is appreciated that "condition A" can be a stress test condition in which an at or about 1200 mm length fin is clamped at both ends, and "condition B" can be the same fin stress tested that is supported in the middle.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a schematic diagram of an embodiment of a refrigerant circuit in a heating, ventilation, air conditioning, and refrigeration (HVACR) system.
Figure 2 shows an internal schematic view of a fin-and-tube heat exchanger according to an embodiment.
Figure 3 is a top view of a fin according to an embodiment.
Figure 4 is a cross-sectional view of the fin as in the embodiment of Figure 3.
Figure 5 is a perspective detailed view showing one of the elliptical collar bases and one pair of the airfoils as in the embodiment of Figure 3.
Figure 6 is a detailed top view of one of the elliptical collar bases according to an embodiment.
Figure 7 is an enlarged side view of the airfoil according to an embodiment.
Figure 8A shows a computational fluid dynamics (CFD) of fluid flow on the second side of the fin according to a comparative design.
Figure 8B shows the CFD of fluid flow on the second side of a fin according to an embodiment.
Figure 8C shows the CFD of fluid flow on the first side of a fin according to the comparative design of Figure 8A.
Figure 8D shows the CFD of fluid flow on the first side of a fin according to an embodiment.
Figure 9A shows locations of planes 1 and 2 over a fin on which the CFDs are computed.
Figure 9B is a legend for showing colors corresponding to the velocities of fluid flows shown in the CFDs of Figures 9C-9F.
Figure 9C shows the CFD of fluid flow on plane 1 of a fin according to a comparative design.
Figure 9D shows the CFD of fluid flow on plane 1 of a fin according to an embodiment.
Figure 9E shows the CFD of fluid flow on plane 2 of the fin of the comparative design of Figure 9C.
Figure 9F shows the CFD of fluid flow on plane 2 of the fin according to an embodiment.
Figure 10A shows locations of planes 3 and 4 over a fin on which the CFDs are computed.
Figure 10B is a legend for showing colors corresponding to the velocities of fluid flows shown in Figures 10C-10F.
Figure 10C shows the CFD of fluid flow on plane 3 of a fin according to the comparative design of Figure 9C.
Figure 10D shows the CFD of fluid flow on plane 3 of a fin according to an embodiment.
Figure 10E shows the CFD of fluid flow on plane 4 of the fin of the comparative design of Figure 9C.
Figure 10F shows the CFD of fluid flow on plane 4 of the fin according to an embodiment.

Like numbers represent like features.

DETAILED DESCRIPTION

This disclosure relates to fins of a heat exchanger for refrigerant circuits for a heating, ventilation, air conditioning, and refrigeration ("HVACR") system. More particularly, this disclosure relates to fins having elliptical collar bases and airfoils for, when a fluid crossflows the heat transfer tubes at the elliptical collar bases, reducing an area of fluid stagnation due to wake detachment in the trailing area behind of the heat transfer tubes that extend through the fins.
Figure 1 is a schematic diagram of an embodiment of a refrigerant circuit 101 in a heating, ventilation, air conditioning, and refrigeration (HVACR) system 100. The HVACR system 100 may be an industrial, commercial, or residential HVACR system 100 configured to condition the inside of a building (e.g., office space, residential house, or the like). In an embodiment, the HVACR system 100 may be a transport climate control system for heating or cooling the inside of a transport unit (e.g., a shipping container, a transport/trucking container, a reefer, or the like) and/or a passenger vehicle (e.g., a bus, a plane, or the like).
In an embodiment, the refrigerant circuit 101 includes a compressor 110, a condenser 120, an expander 130, and an evaporator 140. In an embodiment, the refrigerant circuit 101 can be modified to include additional components. For example, the refrigerant circuit 101 in an embodiment can include an economizer heat exchanger, one or more flow control devices, a receiver tank, a dryer, a suction-liquid heat exchanger, or the like. The components of the refrigerant circuit 101 are fluidly connected. Dotted lines and dotted dashed lines are provided in Figure 1 to indicate fluid flows through the components (e.g., condenser 120, evaporator 140) for clarity, and should be understood as not specifying a specific route within each component.
In an embodiment, the refrigerant circuit 101 applies known principles of gas compression and heat transfer. The refrigerant circuit can be configured to heat or cool a process fluid (e.g., water, air, chiller fluid, or the like). In an embodiment, the refrigerant circuit 101 may represent in a chiller that cools a process fluid such as water or the like. In an embodiment, the refrigerant circuit 101 may represent an air conditioner and/or a heat pump that cools and/or heats a process fluid such as air, water, or the like.
During the operation of the refrigerant circuit 101, a working fluid (e.g., a refrigerant, a refrigerant mixture, or the like) flows into the compressor 110 from the evaporator 140 in a gaseous state at a relatively lower pressure. The compressor 110 compresses the gaseous state working fluid into a high pressure state, which also heats the gas. After being compressed, the relatively higher pressure and higher temperature gaseous state working fluid flows from the compressor 110 to the condenser 120. In addition to the working fluid flowing through the condenser 120, a first process fluid PF₁ (e.g., external air, external water, cooling/heater water, or the like) also separately flows through the condenser 120. The first process fluid absorbs heat from the working fluid as the first process fluid PF₁ flows through the condenser 120, which cools the working fluid as it flows through the condenser. The working fluid condenses to liquid and then flows into the expander 130. The expander 130 allows the working fluid to expand, which converts the working fluid to a mixed vapor and liquid state. An "expander" as described herein may also be referred to as an expansion device. In an embodiment, the expander may be an expansion device such as an expansion valve, expansion plate, expansion vessel, orifice, or the like, or other such types of expansion mechanisms. It should be appreciated that the expander may be any type of expander used in the field for expanding a working fluid to cause the working fluid to decrease in pressure and temperature. For example, the expander can be configured for throttling the working fluid from liquid state with high pressure and high temperature state to two-phase (e.g., a mixture of liquid and vapor) having low pressure and low temperature.
The relatively lower temperature, the two-phase working fluid then flows into the evaporator 140. A second process fluid PF₂ (e.g., air, chiller liquid, water, or the like) also flows through the evaporator 140. The working fluid absorbs heat from the second process fluid PF₂ as it flows through the evaporator 140, which cools the second process fluid PF₂ as it flows through the evaporator 140. As the working fluid absorbs heat, the working fluid evaporates to vapor. The working fluid then returns to the compressor 110 from the evaporator 140. The above-described process continues while the refrigerant circuit 101 is operated, for example, in a cooling mode.
The refrigerant circuit 101 can be configured as a cooling system (e.g., a chiller of an HVACR, an air conditioning system, a heat pump of an HVACR, or the like) that can be operated in a cooling mode, and/or the refrigerant circuit 101 can be configured to operate as a heat pump system that can run in a cooling mode and a heating mode. In an embodiment, the refrigerant circuit 101 is a chiller that cools the second process fluid PF₂ that is a chiller liquid (e.g., air, water, glycol and/or water mixture, or the like). In an embodiment, the refrigerant circuit 101 is a heat pump that cools and heat the second process fluid PF₂ (e.g., air, water, glycol and/or water mixture, or the like).
Figure 2 shows an internal schematic view of a fin-and-tube heat exchanger 200 according to an embodiment. The view of Figure 2 omits the housing (and/or a frame of the heat exchanger) for the heat exchanger 200 to illustrate the fins and tubes of the heat exchanger 200. In an embodiment, the heat exchanger 200 can be the condenser 120 or the evaporator 140 as shown and described in Figure 1. As shown in Figure 200, the heat exchanger 200 includes a plurality of fins 210 stack on top of each other and a plurality of heat transfer tubes ("tubes") 220 that extend through the fins 210.
In an embodiment, the fin 210 includes a corrugated plate 205 having a wavy shape with alternating folds 250 and 260. For example, the corrugated plate 205 can have a zig-zag shape. The corrugated plate 205 has a first side 201 and a second side 202 opposite to the first side 201 of the corrugated plate 205. In an embodiment, the folds 250 and 260 can be peaks 250 and valleys 260 that are located on the plurality of fins 210, and the folds 250 and 260 are aligned in the direction D. In an embodiment, the folds 250 and 260 alternate, between being the peaks and valleys, in the direction of the fluid flow of the first fluid 230. It is appreciated that the folds 250 and 260 can be characterized as peaks 250 and valleys 260 relative to the view of Figure 2 and/or with respect to a first side 201 of the corrugated plate of the fin 210. The first fluid 230 flows in a flow path between the fins 210 (e.g., including the fin collar bases) and the outer surface of the tubes 220. It is appreciated that, in some embodiments, the tube 220 can be attached to the inside of the fin collar 325 (shown in Figure 4) that is connected to the elliptical fin collar bases. In some embodiments, the tube and the fin collar may be contacted by interference fit.
In an embodiment, a wave of the wavy shape of the fin 210 includes one downward fin plate from a peak 250 to a valley 260 and the next adjacent upward fin plate from the same valley 260 to the next adjacent peak 250. The fin 210 may include an optimized fin wave number per row of heat transfer tube for the fin-and-tube heat exchanger. In an embodiment, an angle between the downward fin plate and the upward fin plate may be in a predetermined angle range.
At least one of the tubes 220 extends through at least one of the fins 210 and couples with the fins 210. In an embodiment, the plurality of tubes 220 extend through the plurality of fins 210. The tubes 220 can interference fit into the opening in the fin collar bases and/or the fin collar (shown in Figure 5), for example, by inserting and extending the tubes through the openings on the elliptical collar bases. The fin-and-tube heat exchanger facilitates heat transfer through the tubes 220 and fins 210 between first fluid 230 and the second fluid 240.
The first fluid 230 is arranged to flow through the space between the fins 210 (e.g., above or below the fin with the tubes disposed therein and closely contacted). The second fluid 240 is arranged to flow through the space within the tubes 220. The first fluid 230 can exchange thermal energy with the second fluid 240 through the fins 210 and the tubes 220. The first fluid 230 can flow above, between, and below the fins 210.
In an embodiment, the first fluid 230 can be air, e.g., return indoor air from a climate controlled space to be conditioned (e.g., heated, cooled, or the like) in the fin-and-tube heat exchanger 200. In another embodiment, the first fluid 230 can be outside air to be conditioned by the second fluid 240 flowing in the tubes 220. The second fluid 240 can be a refrigerant, a refrigerant mixture, or the like. The tubes 220 are arranged in parallel with each other and/or perpendicular with the fins 210. The fins 210 may be arranged to be parallel with each other.
It is appreciated that, as shown in Figure 2, when viewing in the direction D of the flow of the second fluid 240, the tubes 220 are arranged in a grid pattern (e.g., in-line, staggered, or the like). In an embodiment, the tubes 220 can be arranged in a staggered pattern as shown, e.g., in Figure 3.
Figure 3 is a top view of a fin 300 according to an embodiment. In an embodiment, Figure 3 can be a top view of the fin 210 viewing in the direction D of Figure 2. The fin 300 includes one or more elliptical collar bases 310 disposed on a corrugated plate having a plurality of folds 305. The folds 305 can be the folds 250 and 260 as discussed above of Figure 2.
As shown in Figure 3, the fin 300 includes a plurality of elliptical collar bases 310 for guiding a flow pattern for the first fluid 230 flowing over and/or under the fin 300. The first fluid 230 is guided to flow in the flow pattern around the heat transfer tubes (e.g., tubes 220 of Figure 2) and extending through the space above and/or below the fin 300. In an embodiment, the first fluid 230 is guided to crossflow the tubes (e.g., 220 of Figure 2) to the trailing area of the tube, guided by the airfoils.
In an embodiment, the first fluid 230 flows in the space between two adjacent fins of a stack of the fins (e.g., as shown by the stack of fins 210 in Figure 2).
An opening 320 is disposed in a plurality, or all, of the elliptical collar bases 310. The opening 320 is arranged to receive the tube (e.g., tube 220 as shown in Figure 2) that can extend through the fins 300 at the elliptical collar base 310 (e.g., at a location in the fin collar base 310). The opening 320 can be a space defined by a fin collar 325 surrounding the opening 320. The fin collar 325 can contact with an external surface of the tube (e.g., the surface 225 of the tube 220 as shown in Figure 2) to facilitate heat transfer through the tubes and the fins 300. In an embodiment, the fin collar 325 can be a circular/round structure, or a tubular section of a flange, extended from the opening 320 of the collar base 310 configured to receiving a heat transfer tube (not shown). It is appreciated that, in some embodiments, the fin collar 325 may have a height that correlates with a fin pitch, or a wave height (e.g., a vertical distance between the peak and the valley of the corrugated plate of the fin 300) of the fins 300. In an embodiment, the opening 320 has a circular shape and a center 350 such that the openings 320 are centered on the folds 305 of the fin 300. It is appreciated that, in an embodiment, an opening 320 is disposed in each and all of the elliptical collar bases 310.
In an embodiment, the fin collars 325 are contacted with the external surface of the tubes (e.g., the surface 225 of the tube 220 as shown in Figure 2) and having an interference fit with the tubes to facilitate heat transfer through the tubes/fin collars and the fins 300. It is appreciated that the fin collar 325 can have a circular wall.
One or more trailing areas 315 are in the flow path of the first fluid 230, downstream of the elliptical collar bases 310, the fin collars (shown in Figure 4), and/or the tubes (shown in Figure 4). For example, the trailing area 315A is in the flow path downstream of the elliptical collar base 310A (and/or the tube and fin collars associated with the elliptical collar base 310A) relatively to the flow direction of the first fluid 230.
It is appreciated that, when the first fluid flows across a heat transfer tube, a separation point presents in the area trailing/behind the heat transfer tube. After the separation point, vortex forms, causing wake detachment and stagnation zone behand the tube. It is appreciated that the trailing areas 315 are in the flow path above and below the fin 300 trailing the locations of the elliptical collar bases 310, the fin collar (not shown), and/or tubes (not shown) relative to the flow direction of the fluid 230.
One or more leading areas 316 are in the flow path of the first fluid 230, upstream of the trailing areas 315. For example, the leading area 316A is in the flow path upstream of the trailing area 315A (in some embodiments, including the tubes and/or fin collars therein) relatively to the flow direction of the first fluid 230. In an embodiment, the trailing area 315 and the leading area 316 are adjacent to each other. In an embodiment, the leading area 316 is a region on the fin 300 upstream of a tube, a fin collar and/or the location, where the velocity vector or the local flow direction of the first fluid 230 is flowing in the overall flow direction 230. It is appreciated that the flow path of the first fluid 230 may flow over, and/or between, the fins, the fin collars, and/or around the heat transfer tubes that extend through the fin 300, as illustrated, e.g., in the computational fluid dynamics of Figures 8B and 8D.
A plurality pairs of airfoils 340 are located on the corrugated plate. As shown in Figure 3, one pair of the airfoils 345 of the plurality airfoils 340 is located around one of the elliptical collar bases 310A. In an embodiment, one pair of airfoils 340 is located respectively around at least some, or all, of the elliptical collar bases 310 on the fin 300. The pair of airfoils 340 are located on the fin 300 such that the airfoils 340 extend from the trailing areas 315 to the leading area 316 of the same elliptical collar base 310, the tube (not shown), and/or the fin collar (not shown). It is appreciated that the airfoils 340 are configured for guiding the flow pattern of the first fluid 230 in the leading areas 316 to the trailing areas 315 around the elliptical collar bases 310, the fin collars (not shown) and/or the tubes (not shown) that extend through the fins 300 at the elliptical collar base 310. In an embodiment, each of the airfoils in the pairs of airfoils 340 extends from the trailing area 315 to the leading area 316 of the same elliptical collar base 310, the tube (not shown), and/or the fin collar (not shown).
The fin 300 has one, two, or more edges at the ends of the fin 300. For example, the edge 301 is disposed at a leading end of the fin 300 and the edge 302 is disposed at a trailing end of the fin 300. The leading end may be located at an end of the fin 300 that is upstream (relative to the flow direction of the first fluid 230) of the elliptical collar bases 310 and/or at a location where the first fluid 230 enters across the fins in a fin-and-tube heat exchanger. The trailing end may be the end of the fin 300 that is downstream of the elliptical collar bases 310 and/or at a location where the first fluid 230 exits the fin in a fin-and-tube heat exchanger. One or both of the edges 301 and 302 can be rippled edge(s) with folds/corrugations extend across, and/or orthogonal to, the flow direction of the first fluid 230. It is appreciated that, by having rippled edge(s), the stiffness of the fin 300 may be improved over the same design of the fin without the corrugated edge(s). In an embodiment, the two edges of the fin 300 can be rippled edges.
Figure 4 is a cross-sectional view of the fin 300 according to an embodiment. For example, Figure 4 can be the cross-sectional view of the fin 300 at the line 390 as in Figure 3. The line 390 can be located through the centers of elliptical collar bases 310C and 310D as in Figure 3.
The fin 300 includes a corrugated plate 400. The elliptical collar bases 310 and the airfoils 340 are disposed on the corrugated plate 400. The corrugated plate 400 includes a first side 410 and a second side 420 opposing the first side 410. In an embodiment, the first side 410 is the upper surface of the corrugated plate 400, and the second side 420 is the lower surface of the corrugated plate 400.
The corrugated plate 400 of the fin 300 has a wave height 430 and an angle 450 (e.g., v-waffle angle). The wave height 430 can be a vertical distance between a peak fold 431 and a valley fold 432 of the corrugated plate 400. In an embodiment, the wave height 430 can be a vertical distance between the highest point on the first side 410 and the lowest point on the second side 420 of the corrugated plate 400 as in the cross-sectional view of Figure 4.
In an embodiment, the angle 450 can have a range of at or about 150° to at or about 160°. For example, the angle 450 can be at or about 150°, 156.3°, 160°, or the like. It is appreciated that the angle may be one of the fin design factors to optimize fin performance. The wave height 430 may depend on the v-waffle angle and correspond the dimension to related v-waffle angle, e.g., as at or about 1.2761 mm, at or about 1 mm, at or about 0.8398 mm, and/or the like.
Figure 5 is a perspective detailed view showing one of the elliptical collar bases 310 and one pair of the airfoils 340 as shown in Figure 3. For example, Figure 5 may be the elliptical collar base 310A and its airfoils 345 as in Figure 3.
As shown in Figure 5, the elliptical collar base 310 extends from the corrugated plate 400 and protrudes from the first side 410. The elliptical collar base 310 has a top surface 510. The top surface 510 may be a flat surface. The corrugated plate 400 connects to the top surface 510 of the elliptical collar base 310 by a transitioning side 520 that is at least partially surrounding the top surface 510 of the elliptical collar base 310. The transitioning side 520 can wedge outwardly from the elliptical collar base 310 to the corrugated plate 400. The transitioning side 520 can have a predetermined transitional angle between the transitioning side 520 and the corrugated plate 400 (e.g., intersecting downward and upward fin plates on the first side 410 of the corrugated plate 400).
The corrugated plate 400 includes the first side 410, a second side (obstructed), and a plurality of folds 501 - 504. The folds 501 - 504 are arranged to be alternative peaks and valleys with respect to the view of Figure 5 such that the folds 501 and 503 may be peaks, and the folds 502 and 504 may be valleys, on the corrugated plate 400 with respect to the first side 410 of the corrugated plate 400.
In an embodiment, the top surface 510 of the elliptical collar base 310 includes an inner edge 512 and an outer edge 514. The inner edge 512 is circular for arranging around a cylindrical heat transfer tube. For example, the inner edge 512 can be circular for providing a circular opening at an end of the fin collar 325 in which the heat transfer tube (not shown) may be inserted through the opening of the elliptical collar base and the fin collar, and penetrated through the corrugated plate 400.
The outer edge 514 can have an elliptical shape that has a major and a minor axis. In an embodiment, the elliptical shape's minor axis of the outer edge 514 is located on the same line for the peak fold 503. The major axis of the outer edge 514 can be perpendicular to the line for the peak fold 503. In an embodiment, the dimension of minor axis and major axis of the outer edge 514 can provide superior fin stiffness regarding the maximum deformation and maximum stress that can be sustained by the fin before plastic deformation and/or cracking occurring to the fin. For example, the fin may be subjected to stress concentration or localized material yielding by its own weight, resulting plastic deformation on the fin under certain conditions. It is appreciated that the elliptical shape may have a continuously curving outer edge line.
In an embodiment, the elliptical collar base 310 can be characterized to be centered over the fold 503 when the inner edge 512 and the outer edge 514 are co-centered on the fold 503. In an embodiment, the top surface 510 of the can be parallel to the overall extending direction D_extending (shown in Fig. 4) of the corrugated plate 400. In an embodiment, the top surface 510 of the elliptical collar base 310 is flush with the peak 503.
In an embodiment, a plurality, or all, of the elliptical collar bases 310 (e.g., shown in Figure 3) protrude from the first side 410 of the corrugated plate 400 on, and/or over, the folds of the corrugated plate 400. At least some, or all, of the elliptical collar bases 310 are centered on the peaks of the folds (e.g., folds 503) of the corrugated plate 400 such that the peak fold 503 and the collar bases 310 protrude from the same side of the corrugated plate 400 and extend in the same direction. In an embodiment, the collar base 310 is arranged to span across three adjacent folds (e.g., 502, 503, 504) on the corrugated plate 400, and/or within five adjacent folds. For example, the top surface 510 of the elliptical collar base 310 includes an opening in the center for receiving a heat transfer tube. It is appreciated that the elliptical collar base may define a transition angle between a leading side 520A and a downward corrugated fin plate section on one side of the elliptical collar base 310, and define a transition angle between a trailing side 520B and an upward corrugated fin plate section on the other side, relative to the one side of the elliptical collar base 310 on the corrugated plate 400.
The transitioning side 520 can connect the top surface 510 of the elliptical collar base 310 to the first side 410 of the corrugated plate 400 and/or provides rigidity/stiffness, e.g., regarding the maximum deformation and maximum stress that can be sustained by the fin before plastic deformation or cracking. For example, the fin may be subjected to stress concentration or localized material yielding by its own weight, resulting plastic deformation on the fin under certain conditions. The transitioning side 520 wedges outwardly from the top surface 510 of the elliptical collar base 310 to the first side 410 of the corrugated plate 400. In an embodiment, the side wall 520 includes a trailing side 520B and a leading side 520A. The trailing side 520B is located in the trailing side of the fluid flow and extended from the fold 503 (peak), across fold 502 (valley), and toward fold 501 (peak). The leading side 520A is located on the leading side of the fluid flow and extended from fold 503 (peak), across fold 504 (valley), and toward the next adjacent fold (peak) on the corrugated plate 400.
The pair of airfoils 340 is disposed at least partially in the trailing area 315 of the corresponding elliptical collar base 310. In an embodiment, the pair of airfoils 340 is disposed fully in the trailing area 315 of the corresponding elliptical collar base 310.
In an embodiment, the elliptical collar base 310 protrudes from the first side 410 on a peak fold (e.g., fold 503) and the airfoil 340 protrudes from the second side (e.g., second side 420 as shown in Figure 4) across a valley fold (e.g., fold 502) such that the elliptical collar base 310 and the airfoils 340 protrudes from opposite sides of the corrugated plate 400. In an embodiment, the airfoil 340 recesses into the first side 410 over a valley fold (e.g., fold 502).
Figure 6 is a detailed top view of one of the elliptical collar base according to an embodiment. For example, Figure 6 can be the detailed top view of one of the elliptical collar bases 310 as shown in Figure 3. The surface of the elliptical collar base 310 has an elliptical shape that includes a first end 311C, a second end 311D, a first side 311A and a second side 311B. The elliptical shape has a major axis Y and a minor axis X through the center 350 of the elliptical shape. It is appreciated that the major axis Y extends along the wider dimension of the elliptical shape between the first end 331C and the second end 311D, and the minor axis X extends along the narrower dimension of the elliptical shape between the first side 311A and the second side 311B.
It is appreciated that the major axis Y and the minor axis X separate the area around the elliptical collar base 310 (and/or around the tube (not shown) disposed therein) into the first to the fourth quadrant 601 - 604. The trailing area 315 of the elliptical collar base 310 may be disposed in the first and second quadrants 601 and 602 downstream of fluid flow passing the fin collar base 310, the fin collar, and/or the tube (not shown) disposed through the fin collar.
The leading area 316 of the elliptical collar base 310 may be disposed in the third and fourth quadrants 603 and 604 upstream of fluid flow passing the fin collar base 310, the fin collar, and/or the tube (not shown) disposed through the fin collar. In an embodiment, the first airfoil 340A of the pair of airfoils 340 is disposed in the first quadrant 601, and the second airfoil 340B of the pair of airfoils 340 is disposed in the second quadrant 602.
The airfoil 340 can have an eyebrow shape (e.g., an arc shape having wedged shaped end and a sharp end) around the elliptical collar base 310. The eyebrow shape of the airfoils 340 can have a trailing end and a leading end. The trailing end of the airfoils 340 extends from the trailing area 315 to the leading end of the airfoils 340 in, or toward, the leading areas 316 of the elliptical collar bases 310. It is appreciated that a heat transfer tube may be disposed through the elliptical collar bases 310 and the fin collar.
In an embodiment, the pair of airfoils 340 are disposed at a location of the corrugated fin plate spaced apart from an outer edge of the elliptical collar base. It is appreciated that the elliptical collar base may be located across a first wave (i.e., a portion of the corrugated plate between, sequentially, a peak, a valley, and a peak) and a second wave adjacent to the first wave. The first wave is upstream of the second wave. The pair of airfoil 340 is disposed in the second wave of the respective elliptical collar base, fin collar, and/or the heat transfer tube disposed through the elliptical collar base.
The airfoils 340 can each have a trailing end 341 and a leading end 342. The trailing end 341 is disposed in the trailing area 315, and the airfoil 340 extends toward the leading area 316 such that the trailing end 341 is closer to the elliptical collar base 310 than the leading end 342. It is appreciated that the trailing end 341 of the airfoil can be disposed at a location closer to the outer edge 514 of the collar base 310 than the location for the leading end 342 of the airfoil, according to an embodiment. In the illustrated examples, the airfoils 340 are continuously extended between the leading end 342 and the trailing end 341. It is appreciated that the airfoils 340 may be provided in two segments (e.g., a leading segment and a trailing segment that disjoin at the valley fold), in three segments, and/or in more segments.
The elliptical collar base 310 is disposed in the orientation such that the elliptical collar base is narrower across/perpendicular to the airflow direction and wider in the airflow direction. In such an orientation, a larger clearance can be provided between two adjacent elliptical collar bases 310 such that interference between two leading ends of the airfoils 340 for adjacent elliptical collar bases 310 may be avoided. It is appreciated that such orientation may provide superior heat transfer.
Figure 7 is an enlarged side view of the airfoil according to an embodiment. For example, Figure 7 can be a side view of the airfoil 340B as shown in Figure 6. As shown in the illustrative example of Figure 7, the corrugated plate 400 has the first side 410 and the second side 420. In the illustrative example of Figure 7, the airfoil 340B can have a uniformed thickness T in the side view of the fin 300. The thickness T of the airfoil 340B can be defined as the distance, in an orthogonal direction the local section (i.e., the upper section or lower section of the corrugated plate between two adjacent folds) of the corrugated plate 400, between the first side 410 of the corrugated plate 400 and the lower surface 701 of the airfoil 340B. In an embodiment, the thickness is at or about 0.4 mm to at or about 0.6 mm.
Figures 8A-D include computational fluid dynamics (CFD) simulations of the fin having an elliptical collar base with a pair of airfoils according to an embodiment, and the CFD of a comparative design. Figure 8A is the CFD of fluid flow on the second side of the fin according to a comparative design. Figure 8B is the CFD of fluid flow on the second side of a fin according to an embodiment. Figure 8C is the CFD of fluid flow on the first side of a fin according to the comparative design of Figure 8A. Figure 8D is the CFD of fluid flow on the first side of a fin according to an embodiment. For example, the fin shown in Figure 8A and 8C can be a fin without the airfoils of the embodiments of this disclosure. Figure 8B can be the fin 300 as shown, e.g., in Figure 4, viewing from the second side 420 of the fin 300. Figure 8D can be the fin 300 as shown, e.g., in Figure 4, viewing from the first side 410 of the fin 300. It is appreciated that, the tubes extending through the fin are omitted in Figures 8A-8D.
Figure 8A shows the CFD in a layer of the flow path on the bottom of the fin as a comparative design. Area 810 is located in the flow path with white or light gray dashes showing the presence of fluid flows. Area 820A indicates a portion of the trailing area (relative to the fluid flow direction) of the elliptical collar base, the fin collar, and/or the heat transfer tube may be disposed therein. With few white or light gray dashes covering the area 820A, the features of the fin itself are clearly shown, indicating a stagnation of fluid flow in this area 820A, due to wake detachment in the trailing area behind the heat transfer tube (and/or the fin collar and the collar base). It is appreciated that stagnated fluid can have a lower rate of heat transfer compared to area with fluid flow. Accordingly, by causing more fluid flow into the stagnated area, the fluid-side heat transfer coefficient of the fin (e.g., air-side heat transfer coefficient) may be improved.
Figure 8B shows the CFD in a layer of the flow path on the bottom of the fin having an elliptical collar base and a pair of airfoils according to an embodiment of the present disclosure that reduces stagnation of fluid flow. As shown in Figure 8B, a smaller portion of the area 820B on the fin is more clearly shown compared to the area 820A of Figure 8A. The area 820B has a larger portion of the feature on the fin obstructed by white or light gray dashes that indicate the presence of fluid flow. Accordingly, a smaller portion in the area 820B has stagnation of fluid flow thereby having a higher heat transfer comparing to the fin of Figure 8A.
Figure 8C shows the CFD in a layer of the flow path on the top of the fin as a comparative design. Area 810 is in the flow path with white or light gray dashes showing fluid flows. Area 820C shows the trailing area (relative to the fluid flow direction) of the fin collar, the fin collar base, and/or the heat transfer tube. With fewer white or light gray dashes covering a larger portion in this area 820C, the features of the fin are more clearly shown in Figure 8C indicating a larger stagnation of fluid flow in this area 820C.
Figure 8D shows the CFD in a layer of the flow path on the top of the fin having an elliptical collar base and a pair of airfoils according to an embodiment of the present disclosure. As shown in Figure 8D, a smaller portion of area 820D on the fin is clearly shown within the area 820D, compared to Figure 8C. Accordingly, a smaller portion in the area 820D has stagnated fluid flow due to the reduction of stagnated fluid flow, for example, from the reduction of wake formed in the trailing area.
Comparing with the CFDs in Figure 8A and 8C (for a fin of a comparative design), the CFDs in Figures 8B and 8D (for a fin according to one or more embodiments) show a higher fluid-side heat transfer coefficient (when fluid flows over the fin). The improvement to the fluid-side heat transfer coefficient can be due to the reduction of stagnated fluid flow that at least partially caused by reducing wake detachment trailing the heat transfer tubes in the trailing area of the elliptical collar bases.
It is appreciated that, generally, a lower pressure drop across the fin can be more preferable for using less energy for moving fluids through the fin-and-tube heat exchanger. Also, a higher fluid-side heat transfer coefficient can be generally more preferable as the same heat transfer area on the fin can support a larger amount of heat transfer.

Aspects:

Any of Aspects 1 - 13 may be combined with any of Aspects 14 - 20.

Aspect 1. A fin comprising:
- a corrugated plate having a first side and a second side opposing the first side, the corrugated plate having a plurality of folds that includes alternative peaks and valleys relative to the first side of the corrugated plate;
- one of a plurality of elliptical collar bases protruding from the first side of the corrugated plate; and
- a first airfoil and a second airfoil extending between a major axis and a minor axis of, and curving around, the one of the plurality of elliptical collar bases, wherein
  - the first airfoil is disposed in a first quadrant for the one of the plurality of elliptical collar bases, and
  - the second airfoil is disposed in a second quadrant for the one of the plurality of elliptical collar bases, the second quadrant being adjacent to the first quadrant at the major axis.
Aspect 2. The fin of aspect 1, wherein the one of the plurality of elliptical collar bases embosses into the second side and protrudes from the first side over one of the peaks.
Aspect 3. The fin of aspect 1 or 2, wherein the one of the plurality of elliptical collar bases extends across three adjacent folds on the corrugated plate and within five adjacent folds on the corrugated plate.
Aspect 4. The fin of any one of aspects 1 - 3, wherein
a transitioning side connects the one of the plurality of elliptical collar bases to the corrugated plate.
Aspect 5. The fin of aspect 4, wherein
the transitioning side wedges outwardly from the one of the plurality of elliptical collar bases to the first side of the corrugated plate.
Aspect 6. The fin of any one of aspects 1 - 5, wherein
the one of the plurality of elliptical collar bases is centered over one of the peaks.
Aspect 7. The fin of any one of aspects 1 - 6, wherein
the one of the plurality of elliptical collar bases is flush with the one of the peaks.
Aspect 8. The fin of any one of aspects 1 - 7, wherein
the first airfoil extends across one of the valleys in a trailing area of the one of the plurality of elliptical collar bases.
Aspect 9. The fin of any one of aspects 1 - 8, wherein
the first airfoil comprises
- a trailing end extended toward the major axis of the one of the plurality of elliptical collar bases and
- a leading end extended toward the minor axis of the one of the plurality of elliptical collar bases.
Aspect 10. The fin of any one of aspects 1 - 9, wherein
a leading end of the first airfoil is disposed further away from the one of the plurality of elliptical collar bases than a trailing end of the first airfoil.
Aspect 11. The fin of any one of aspects 1 - 10, wherein
the first airfoil is extended within three adjacent folds of the corrugated plate.
Aspect 12. The fin of any one of aspects 1 - 11, wherein
the first airfoil embosses into the first side and protrudes from the second side of the corrugated plate.
Aspect 13. The fin of any one of aspects 1 - 12, wherein the fin further includes a rippled edge.
Aspect 14. A fin-and-tube heat exchanger comprising:
a plurality of heat transfer tubes extending through a plurality of fins, wherein one of the plurality of fins comprise:
- a corrugated plate having a first side and a second side opposing the first side, the corrugated plate having a plurality of folds that includes alternative peaks and valleys relative to the first side of the corrugated plate;
- one of a plurality of elliptical collar bases protruding from the first side of the corrugated plate; and
- a first airfoil and a second airfoil extending between a major axis and a minor axis of, and curving around, the one of the plurality of elliptical collar bases, wherein
  - the first airfoil is disposed in a first quadrant for the one of the plurality of elliptical collar bases, and
  - the second airfoil is disposed in a second quadrant for the one of the plurality of elliptical collar bases, the second quadrant being adjacent to the first quadrant at the major axis.
Aspect 15. The fin-and-tube heat exchanger of aspect 14, wherein
- the one of the plurality of elliptical collar bases embosses into the second side and protrudes from the first side over one of the peaks, and
- the first airfoil embosses into the first side and protrudes from the second side of the corrugated plate.
Aspect 16. The fin-and-tube heat exchanger of claim 14, wherein
- the one of the plurality of fins further comprises a fin collar connected to the one of the plurality of elliptical collar bases, and
- an external surface of one of the heat transfer tubes is contacted with the fin collar.
Aspect 17. The fin-and-tube heat exchanger of claim 14, wherein
- the first airfoil extends across one of the valleys in a trailing area of the one of the plurality of elliptical collar bases, and
- a leading end of the first airfoil is disposed further away from the one of the plurality of elliptical collar bases than a trailing end of the first airfoil.
Aspect 18. The fin-and-tube heat exchanger of claim 14, wherein
- a transitioning side connects the one of the plurality of elliptical collar bases to the corrugated plate, and
- the transitioning side wedges outwardly from the one of the plurality of elliptical collar bases to the first side of the corrugated plate.
Aspect 19. The fin-and-tube heat exchanger of claim 14, wherein
- the one of the plurality of elliptical collar bases is centered over one of the peaks, and
- the one of the plurality of elliptical collar bases is flush with the one of the peaks.
Aspect 20. The fin-and-tube heat exchanger of claim 14, wherein
the one of the plurality of fins has a leading edge and a trailing edge, and a rippled edge is disposed on one or both of the leading edge and the trailing edge.

The terminology used herein is intended to describe particular embodiments and is not intended to be limiting. The terms "a," "an," and "the" include the plural forms as well, unless clearly indicated otherwise. The terms "comprises" and/or "comprising," when used in this Specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components.
With regard to the preceding description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size, and arrangement of parts without departing from the scope of the present disclosure. This Specification and the embodiments described are exemplary only, with the true scope and spirit of the disclosure being indicated by the claims that follow.

Claims

A fin comprising:
a corrugated plate having a first side and a second side opposing the first side, the corrugated plate having a plurality of folds that includes alternative peaks and valleys relative to the first side of the corrugated plate;

one of a plurality of elliptical collar bases protruding from the first side of the corrugated plate; and

a first airfoil and a second airfoil extending between a major axis and a minor axis of, and curving around, the one of the plurality of elliptical collar bases, wherein
the first airfoil is disposed in a first quadrant for the one of the plurality of elliptical collar bases, and

the second airfoil is disposed in a second quadrant for the one of the plurality of elliptical collar bases, the second quadrant being adjacent to the first quadrant at the major axis.
The fin of claim 1, wherein the one of the plurality of elliptical collar bases embosses into the second side and protrudes from the first side over one of the peaks.
The fin of claim 1 or claim 2, wherein the one of the plurality of elliptical collar bases extends across three adjacent folds on the corrugated plate and within five adjacent folds on the corrugated plate.
The fin of any one of claims 1 to 3, wherein
a transitioning side connects the one of the plurality of elliptical collar bases to the corrugated plate.
The fin of claim 4, wherein
the transitioning side wedges outwardly from the one of the plurality of elliptical collar bases to the first side of the corrugated plate.
The fin of any one of claims 1 to 5, wherein
the one of the plurality of elliptical collar bases is centered over one of the peaks.
The fin of any one of claims 1 to 6, wherein
the one of the plurality of elliptical collar bases is flush with the one of the peaks.
The fin of any one of claims 1 to 7, wherein
the first airfoil extends across one of the valleys in a trailing area of the one of the plurality of elliptical collar bases.
The fin of any one of claims 1 to 8, wherein
the first airfoil comprises
a trailing end extended toward the major axis of the one of the plurality of elliptical collar bases and

a leading end extended toward the minor axis of the one of the plurality of elliptical collar bases.
The fin of any one of claims 1 to 9, wherein
a leading end of the first airfoil is disposed further away from the one of the plurality of elliptical collar bases than a trailing end of the first airfoil.
The fin of any one of claims 1 to 10, wherein
the first airfoil is extended within three adjacent folds of the corrugated plate.
The fin of any one of claims 1 to 11, wherein
the first airfoil embosses into the first side and protrudes from the second side of the corrugated plate.
The fin of any one of claims 1 to 12, wherein the fin further includes a rippled edge, and optionally wherein the rippled edge is disposed on one or both of a leading edge and a trailing edge of the fin.
The fin of any one of claims 1 to 13, wherein
the fin further comprises a fin collar connected to the one of the plurality of elliptical collar bases, and

an external surface of one of the heat transfer tubes is contacted with the fin collar.
A fin-and-tube heat exchanger comprising:
a plurality of heat transfer tubes extending through a plurality of fins, wherein one of the plurality of fins is in accordance with any one of claims 1 to 13.