Micro-channel heat exchanger and louver fins thereof

Abstract

The invention discloses a micro-channel heat exchanger and louver fins thereof. The louver fins are installed on flat pipes. The louver fin comprises a fin base body, a windward louver and a leeward louver are sequentially arranged on the fin base body in the fluid flowing direction, the area between the windward louver and the leeward louver is a redirection area, and penetrating holes penetrating through the fin base body are formed in the redirection area. According to the micro-channel heat exchanger and the louver fin thereof, the penetrating holes penetrating through the fin base body are formed in the redirection area, frost blockage near the redirection area can be relieved, and the heat exchanger can operate for a longer time. Meanwhile, due to the fact that the through holes are formed, defrosting water can be rapidly discharged and cannot stay in the blind window. After the louver fins are perforated, the performance of the micro-channel heat exchanger cannot be obviously reduced, and materials can be saved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and in particular to a microchannel heat exchanger and louvered fins thereof. Background Art

[0002] A microchannel heat exchanger is a compact heat exchange device that utilizes densely packed flat tubes with tiny hydraulic diameters (typically less than 1 mm) as its core heat transfer element. This device significantly increases heat transfer area density and optimizes fluid flow to achieve efficient heat exchange. Its main structure consists of three main components: a core of parallel microchannel flat tubes, a manifold that distributes and collects fluids, and fins located between the tubes to enhance air-side heat transfer.

[0003] Microchannel flat tubes are its signature components, typically extruded from aluminum alloy. They contain dozens or even hundreds of parallel microchannels with extremely small equivalent diameters, resulting in a pronounced microscale effect on the fluid flow. These tubes are sealed and secured to a manifold at both ends through specialized connections (such as brazing). The manifold is typically designed with baffles or specialized structures to ensure proper distribution and collection of refrigerant before and after entering or exiting the individual tubes. Fins, positioned perpendicular to the outer surfaces of the tubes and shaped like louvers or corrugations, disrupt the air boundary layer, enhancing turbulence and further improving heat transfer efficiency on the air side.

[0004] Currently, vertical-fin microchannel heat exchangers (MCHEs) offer superior heat transfer and drainage performance compared to traditional corrugated-fin MCEs. This is primarily due to their unique vertical fins, which can be composed of a combination of flat, corrugated, and windowed structures. By adjusting the order and proportion of each structure, they can be adapted to different operating conditions. Among these, fully louvered vertical fins are more widely used due to their superior heat transfer performance due to their louvered flow diversion.

[0005] However, when the louvered vertical fins operate under wet or frosted conditions, due to their high heat and mass transfer rates, condensed water or frost layers can easily clog the louver opening area and form trapped water in the gaps that is difficult to drain, causing a sharp drop in heat exchanger performance. Summary of the Invention

[0006] Based on this, it is necessary to provide a microchannel heat exchanger and its louver fins to address the problem that when the existing louver vertical fins are operated under wet or frosted conditions, condensed water or frost layers easily clog the louver opening area and form retained water in the gaps that is difficult to drain.

[0007] A louver fin comprises: a fin base, wherein the fin base is provided with a windward louver and a leeward louver in sequence along the direction of fluid flow, the area between the windward louver and the leeward louver is a redirection area, and the redirection area is provided with a through hole penetrating the fin base.

[0008] In one embodiment, the perforations are arranged offset from the centerline of the redirection zone and close to the windward louver.

[0009] In one embodiment, the spacing between the windward louvers gradually decreases along the fluid flow direction, and the spacing between the leeward louvers gradually increases along the fluid flow direction.

[0010] In one embodiment, the distance between the front end of the windward louver and the center line of the redirection zone is smaller than the distance between the rear end of the leeward louver and the center line of the redirection zone.

[0011] In one embodiment, the fin base is provided with an accommodating groove for accommodating the flat tube.

[0012] In one embodiment, the fin base is provided with a drainage groove for drainage.

[0013] In one embodiment, the drainage grooves are provided in two groups, and the two groups of drainage grooves are respectively provided on opposite sides of the fin base, and the two groups of drainage grooves are staggered along the fluid flow direction.

[0014] In one embodiment, a mounting portion with increased width is provided at the end of the fin base along the fluid flow direction.

[0015] In one embodiment, the two ends of the fin base are provided with a first mounting hole and a second mounting hole; The first mounting hole and the second mounting hole are trapezoidal, and the trapezoidal shape of the first mounting hole and the trapezoidal shape of the second mounting hole are symmetrical about their centers.

[0016] A microchannel heat exchanger comprises: a flat tube and any one of the above-mentioned louvered fins, wherein the louvered fins are mounted on the flat tube.

[0017] In the aforementioned microchannel heat exchanger and its louvered fins, because the louvered areas are symmetrical about the redirection zone, the louvers near the redirection zone are first clogged by frost during operation under frosting conditions, restricting flow through the louvers. Therefore, by providing perforations through the fin base in the redirection zone, frost blockage near the redirection zone can be alleviated, extending the heat exchanger's operating time. Furthermore, the perforations allow for rapid drainage of meltwater, preventing it from accumulating between the louvers. Perforating the louvered fins does not significantly reduce the performance of the microchannel heat exchanger and saves material. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the specific embodiments. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0019] Figure 1 Schematic diagram of the structure of a microchannel heat exchanger in one embodiment; Figure 2 for Figure 1 Schematic diagram of the structure of the middle louver fin; Figure 3 for Figure 2 a front view of the louvered fin shown; Figure 4 for Figure 2 a top view of the louvered fins shown; Figure 5 for Figure 1 Schematic diagram of the integrated molding of the louver fins in the same row.

[0020] Reference numerals: 10-flat tube, 20-louver fin, 21-fin base, 211-perforation, 212-accommodation groove, 213-mounting portion, 214-drainage groove, 215-first mounting hole, 216-second mounting hole, 22-windward louver, 23-leeward louver, 24-redirection area, 30-collecting pipe, 31-fluid inlet, 32-fluid outlet. DETAILED DESCRIPTION

[0021] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0024] At present, when the vertical fins of the louver operate under wet or frosted conditions, due to their high heat and mass transfer rates, condensed water or frost layers easily clog the window area of ​​the louver and form retained water in the gaps that is difficult to drain, causing the heat exchanger performance to drop sharply.

[0025] The inventors have found that the main reasons for the decline in operating performance of the louvered vertical fin microchannel heat exchanger under frosting conditions are as follows: since the louver area is symmetrical front to back about the redirection area, the louvers near the redirection area are first blocked by the frost layer when operating under frosting conditions, which restricts the flow of the louvers.

[0026] In response to the above problems, Figure 1 As shown, the present application provides a microchannel heat exchanger, including a flat tube 10 and louvered fins 20 , wherein the louvered fins 20 are mounted on the flat tube 10 , and a plurality of groups of louvered fins 20 are distributed in an array at intervals on the flat tube 10 .

[0027] Please also refer to Figure 2 and Figure 3 In one embodiment, the louvered fin 20 has a length direction a, a width direction b, and a thickness direction c. The length direction a aligns with the flow direction of the fluid. The louvered fin 20 includes a fin base 21. The fin base 21 is generally a sheet-like structure and is typically made of thin metal. For example, the fin base 21 can be made of an aluminum alloy.

[0028] The fin base 21 is provided with windward louvers 22 and leeward louvers 23, arranged in sequence along the direction of fluid flow. The area between the windward louvers 22 and leeward louvers 23 constitutes the redirection zone 24. Specifically, the windward louvers 22 are located at the front end of the fin base 21, while the leeward louvers 23 are located at the rear end. The windward louvers 22 first come into contact with the fluid, quickly breaking the relatively thick laminar boundary layer at the inlet. The fluid then flows through the redirection zone 24 into the area of ​​the leeward louvers 23. The leeward louvers 23 continue to guide the airflow, maintaining the necessary turbulence and transverse flow components, and preventing the airflow from prematurely returning to a laminar or slightly disturbed state.

[0029] Typically, the windward louvers 22 have a larger inclination angle to create a dramatic disturbance in the airflow at the inlet, breaking up the boundary layer and inducing turbulence. The leeward louvers 23 typically have a smaller or moderate inclination angle. Since the airflow has become highly turbulent after being intensified in the windward region, using smaller inclination angles can effectively control the pressure drop increase in the rear section while maintaining a sufficient level of intensification.

[0030] Please also refer to Figure 4 In one embodiment, the inclination angle of the windward louvers 22 is opposite to that of the leeward louvers 23. This breaks up unidirectional vortices and forces a zigzag flow, while also distributing velocity and turbulence, balancing pressure drop, and extending contact time to maximize heat exchange efficiency. Furthermore, the inclination angles of the windward louvers 22 and leeward louvers 23 are equal in magnitude but opposite in direction. This allows the fluid to form vortices in opposite directions in the windward and leeward louvers 22 and 23 regions, enhancing wall heat exchange and slowing frost growth.

[0031] The redirection zone 24 includes a through-hole 211 extending through the fin base 21. Specifically, the through-hole 211 extends through the fin base 21 along the thickness direction c, forming a through-hole structure. The axis of the through-hole 211 can be perpendicular to the fin base 21, meaning the through-hole 211 is vertical. Alternatively, the axis of the through-hole 211 can form a specific angle with the fin base 21, with the through-hole 211 arranged obliquely on the fin base 21.

[0032] Because the louver area is symmetrical about the redirection zone 24, the louvers near the redirection zone 24 are first clogged by frost during operation under frosting conditions, restricting flow through the louvers. Therefore, perforations 211 are provided in the redirection zone 24. This prevents frost from forming in this area, thus delaying frost clogging of the louver fins 20 and extending heat exchanger operation. Furthermore, the presence of perforations 211 allows meltwater to be quickly drained away, preventing it from accumulating between the louvers. Perforations 211 in the louver fins 20 do not significantly reduce the performance of the microchannel heat exchanger and conserve material.

[0033] In one embodiment, the perforations 211 are offset from the centerline d of the redirection zone 24 and positioned closer to the windward louvers 22. That is, the perforations 211 are not located in the center of the redirection zone 24, but closer to the front of the windward louvers 22. Because the windward louvers 22 are near the moist air inlet and are the first to come into contact with moist air, frost forms before the leeward louvers 23. As moist air enters the windward louvers 22 and flows between them, its temperature gradually decreases. It reaches saturation near the front of the redirection zone 24, condensing water and further condensing into frost. Therefore, frost blockage occurs first in this area. Therefore, by placing the perforations 211 closer to the windward louvers 22, aligning them with the location where frost blockage first occurs, the frost layer is free of adhering matter in this area, preventing frost blockage from forming there. This, in turn, reduces frost blockage of the louver fins 20.

[0034] In one embodiment, the spacing between the windward louvers 22 gradually decreases along the fluid flow direction, while the spacing between the leeward louvers 23 gradually increases along the fluid flow direction. The inventors have discovered that frost clogging the windward louvers 22 results in uneven frost distribution in the louver regions in front and behind the redirection zone 24, with more frost in the front and less in the rear. Even if there is space in the leeward louver 23 region, heat and mass transfer with the moist air is impossible.

[0035] Therefore, the spacing of the windward louvers 22 is from large to small, while the spacing of the leeward louvers 23 is from small to large. This can further delay the frost blocking of the windward louvers 22, make the frost formation in the windward louvers 22 and leeward louvers 23 areas more uniform, and fully utilize the fins.

[0036] In one embodiment, the distance e between the front end of the windward louver 22 and the centerline d of the redirection zone 24 is less than the distance f between the rear end of the leeward louver 23 and the centerline d of the redirection zone 24. In other words, the length of the windward louver 22 along the fluid flow direction is shorter than the length of the leeward louver 23 along the fluid flow direction. Therefore, compared to conventional arrangements where the windward and leeward louvers 22 and 23 are symmetrically distributed about the redirection zone 24, the windward and leeward louvers 22 and 23 of the present invention are not symmetrically distributed. The first louver opening of the windward louver 22 is positioned further back than the conventional louver fins 20.

[0037] The inventors have discovered that meltwater tends to remain between the louvers and fins, causing frost to form more quickly during the next frosting operation and a rapid decrease in operating time. The aforementioned perforations 211 in the redirection area 24 and the spacing between the windward louvers 22 and leeward louvers 23 effectively address the problem of meltwater retention in the louver area. The retention of meltwater between the fins can be addressed by extending the opening position of the first louver of the windward louver 22. This reduces the contact area between the meltwater and the fins, thereby reducing surface tension and allowing the meltwater between the fins to fall under its own weight.

[0038] In one embodiment, the fin base 21 is provided with a receiving groove 212 for receiving the flat tube 10, and the louver fin 20 is installed on the flat tube 10 through the receiving groove 212. When the louver fin 20 is installed on the flat tube 10, the louver fin 20 is installed vertically and can be fixed to the outer surface of the flat tube 10 by brazing. After the louver fin 20 is installed, the receiving grooves 212 of the two adjacent louver fins 20 above and below form a space for receiving the flat tube 10. The arc transition between the bottom wall and the side wall of the receiving groove 212 can avoid stress concentration on the fin base 21 on the one hand, and match the shape of the flat tube 10 on the other hand, making it easier to braze the louver fin 20 on the flat tube 10.

[0039] In one embodiment, the end of the fin base 21 along the direction of fluid flow is provided with a mounting portion 213 with an increased width. That is, at the end of the length direction a, the fin base 21 extends outward in an increased size along the width direction b, forming a T-shaped structure. After the louver fin 20 is installed on the flat tube 10, the mounting portions 213 of adjacent louver fins 20 on the upper and lower layers will contact each other due to the increased size of the mounting portion 213 at the end of the louver fin 20. The mounting portions 213 of the upper and lower layers can be fixed by brazing, thereby connecting the upper and lower layers of louver fins 20 as a whole. When processing the louver fin 20, the mounting portion 213 is formed by removing some material to obtain the receiving groove 212 while retaining some material at the end of the fin base 21.

[0040] Please also refer to Figure 5 It is understood that in other embodiments, the upper and lower mounting portions 213 do not need to be brazed to secure them; instead, the upper and lower mounting portions 213 can be integrally formed. In other words, multiple louvered fins 20 are stamped from a single sheet of material. The mounting portions 213 are formed during the stamping process of the receiving grooves 212. After the louvered fins 20 are stamped, all louvered fins 20 in the same row are simultaneously mounted on the flat tubes 10.

[0041] Please refer again Figure 2 and Figure 3In one embodiment, the fin base 21 is provided with drainage grooves 214 for drainage, through which defrost water on the louver fins 20 can be drained. Furthermore, two sets of drainage grooves 214 are provided on the fin base 21. The two sets of drainage grooves 214 are located on opposite sides of the fin base 21, and the two sets of drainage grooves 214 are staggered along the direction of fluid flow. In other words, the louver fin 20 is provided with two sets of drainage grooves 214, one set on opposite sides along the width direction b, and the two sets of drainage grooves 214 are staggered along the length direction a. The staggered arrangement of the two sets of drainage grooves 214 enables front-to-back drainage of the louver fins 20, preventing defrost water from accumulating on the louver fins 20 and affecting their heat exchange efficiency.

[0042] In one embodiment, a first mounting hole 215 and a second mounting hole 216 are provided at both ends of the fin base 21. Fixing members can be inserted into the first mounting hole 215 and the second mounting hole 216 to connect the louver fins 20 in the same row in series and facilitate control of the spacing between adjacent louver fins 20. Furthermore, the first mounting hole 215 and the second mounting hole 216 are both trapezoidal in shape, and the trapezoidal shapes of the first mounting hole 215 and the second mounting hole 216 are symmetrical about their centers.

[0043] The first and second mounting holes 215, 216 are trapezoidal, forming a flexible guide structure. Since the louvered fins 20 are typically secured to the flat tube 10 by brazing, the heat generated during the welding process allows the louvered fins 20 to slide and expand along the oblique edges. After welding, the oblique edges guide the fins to contract and reset, preventing residual stress concentration. Furthermore, the inverse design of the trapezoidal shape of the first mounting hole 215 and the second mounting hole 216 prevents installation errors and improves positioning accuracy.

[0044] Please refer again Figure 1 In one embodiment, the microchannel heat exchanger further includes two manifolds 30, each connected to the ends of the flat tubes 10. The manifolds 30 are used to evenly distribute the refrigerant to the numerous parallel-connected microchannel flat tubes 10. The manifolds 30 are provided with a fluid inlet 31 and a fluid outlet 32. External refrigerant enters the manifold 30 through the fluid inlet 31, is then distributed to the flat tubes 10, and, after heat exchange, is discharged from the fluid outlet 32.

[0045] In the above-mentioned microchannel heat exchanger and its louver fins 20, condensed water or frost is not easy to block the louver opening area, and retained water is easy to be discharged, thereby ensuring the performance of the microchannel heat exchanger.

[0046] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A louver fin, characterized in that: include: The fin base is provided with windward louvers and leeward louvers in sequence along the fluid flow direction, the area between the windward louvers and the leeward louvers is a redirection area, and the redirection area is provided with a through hole penetrating the fin base.

2. The louver fin according to claim 1, characterized in that: The perforations are arranged offset from the centerline of the redirection zone and adjacent to the windward louver.

3. The louver fin according to claim 1, characterized in that: The spacing between the windward louvers gradually decreases along the fluid flow direction, and the spacing between the leeward louvers gradually increases along the fluid flow direction.

4. The louver fin according to claim 1, characterized in that: The distance between the front end of the windward louver and the center line of the redirection zone is smaller than the distance between the rear end of the leeward louver and the center line of the redirection zone.

5. The louver fin according to claim 1, characterized in that: The fin base is provided with an accommodating groove for accommodating the flat tube.

6. The louver fin according to claim 1, characterized in that: The fin base is provided with a drainage groove for drainage.

7. The louver fin according to claim 6, characterized in that: The drainage grooves are provided in two groups, and the two groups of drainage grooves are respectively provided on opposite sides of the fin base, and the two groups of drainage grooves are staggered along the fluid flow direction.

8. The louver fin according to claim 1, characterized in that: The end of the fin base along the fluid flow direction is provided with a mounting portion with increased width.

9. The louver fin according to claim 1, characterized in that: The two ends of the fin base are provided with a first mounting hole and a second mounting hole; The first mounting hole and the second mounting hole are trapezoidal, and the trapezoidal shape of the first mounting hole and the trapezoidal shape of the second mounting hole are symmetrical about their centers.

10. A microchannel heat exchanger, characterized in that: include: It comprises a flat tube and the louver fin according to any one of claims 1 to 9, wherein the louver fin is installed on the flat tube.

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