RU2528235C1 - Perforated fins of heat exchanger - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: plate-fin heat exchanger comprises a folded finned sheet comprising the fins, and the finned sheet comprises a plurality of perforations, and such plurality of perforations is located on the finned sheet in parallel rows, when such finned sheet is in the unfolded state. Such parallel rows of perforations on the finned sheet comprise a first distance between the parallel rows of perforations (S1), a second distance between the successive perforations in the parallel row of perforations (S2), a third distance (or shifting) between the perforations in adjacent parallel rows of perforations (S3), and the diameter (D) of the perforation. The ratio of the first distance between the parallel rows of perforations to the diameter of the perforation (S1/D) is in the range of 0.75-2.0. And the angle between the fins and the parallel rows of perforations is less than or equal to five degrees (≤5°).

EFFECT: improving the geometry of the perforated fin.

18 cl, 3 dwg, 2 tbl

Description

BACKGROUND OF THE INVENTION

Plate-fin heat exchangers are generally used for heat exchange between process streams in order to heat, cool, boil, evaporate or condense process streams. The process conditions in these heat exchangers may relate to single-phase or two-phase flow and heat transfer. While some plate-fin heat exchangers contain only two streams, others contain many streams in many sets of plate-fin passages. Separate streams can be fed into and removed from the heat exchanger using nozzles and manifolds. Each stream flows into specific plate-fin passages associated with a battery of adjacent plate-fin passages. Separate plate-fin passages are contained between pairs of separating sheets that are spaced apart by ribs, and plate-fin passages are surrounded on the outer periphery by side rails and end rails, so that they can be isolated from each other and may contain fluids of interest. When streams of different temperatures flow in plate-fin passages that are adjacent to each other, they exchange heat through dividing sheets called primary heat transfer surfaces, as well as through the legs of the ribs that separate them, which are called secondary heat transfer surfaces.

Lamellar fin heat exchangers can be formed by using many different types of fins, such as flat, perforated, serrated and wavy. One embodiment of the present invention deals with perforated ribs that have been used in industry but inefficiently. Plate-fin heat exchangers having perforated fins according to the present invention have particular application in cryogenic processes such as air separation, although these plate-fin heat exchangers can be used in other heat transfer processes.

When a stream or fluid enters the channel of a finned fin heat exchanger, he / she has high heat transfer coefficients due to the well-known input effect. After the input effect, the flow or fluid will soon reach a steady state condition with a much lower heat transfer coefficient. In particular, when the flow is characterized in that it is in a turbulent state or in a transition state between the laminar and turbulent states, the formation of laminar and viscous boundary layers is known next to all surfaces along which the fluid flows. The overall effect is to lower the average heat transfer coefficients in such a heat exchanger. The condition for a reduced heat transfer coefficient can be at least partially reversed by periodically perturbing this boundary layer by a variety of means, such as, for example, introducing perforations or notches in the ribs. The introduction of perforations or serrations in the ribs will increase the heat transfer performance, however, this introduction will also increase the pressure loss, and therefore the geometry and arrangement of the perforations or serrations in the ribs is critical to achieve improved performance. This is especially important in the case of perforated fins, since while they disturb the flow, leading to an increase in the local heat transfer coefficient near the perforations, the introduction of perforations in the ribs also leads to a loss of surface area from the starting material, which would otherwise be advantageous for the total heat transfer from the heat exchanger. Also, the removal of metal, for example, in the form of perforations can greatly reduce the strength of the remaining material. Thus, the problem of improving the performance of plate-fin heat exchangers through the use of perforated fins is complex, and to achieve improved performance it is especially important to organize the geometry and locations of use of such perforations.

Historically, in publications related to plate-fin heat exchangers, general descriptions of the geometry in general and elementary methods of manufacturing plate-fin heat exchangers were presented. Despite the fact that many of the components of plate-fin heat exchangers are discussed in these publications, their relationship with each other and how they are assembled and brazed together, the publications give brief descriptions of perforated fins that can be used in such plate-fin heat exchangers. Even in cases where some nominal details are described, the publications simply did not discuss any preferred geometry and patterns for use.

For example, in the document “Aluminum Brazed Plate-Finned Heat Exchangers for the Manufacturing Industry”, chapter Compact Heat Exchangers for the Manufacturing Industry, edited by R.K. Shah, minutes from the Cliff Lodge and Conference Center, Snowbird, Utah, June 22-27, 1997, by Shozo Hotta of Sumitomo Precision Products (SPP), a general description of plate fin heat exchangers from SPP, a major supplier such heat exchangers. In particular, FIG. 4 on page 181 of this link provides photographic evidence of common rib types including perforated ribs. As described and taught in that document, perforated ribs are formed by folding a sheet with regularly perforated small circular holes or perforations at a certain large angle relative to the main axis of the perforations on the flat sheet. However, no further details are available.

This manufacturing method is quite common in industry to minimize total costs. Several standard perforated sheet materials can be used to make a wide range of finished ribs with varying sizes. This type of method for manufacturing perforated ribs, however, leads to an irregular arrangement of perforations on the ribs, resulting in poor performance of the perforated ribs.

U.S. Patent No. 6,834,515 B2, entitled "Plate-Finned Heat Exchangers with Surface Textures", issued by Sunder and others, also describes various perforated fins. A Sunder patent teaches the use of surface texture to improve the performance of other perforated ribs. 2B, a Sunder patent shows illustrative ribs with a series of perforations along the top and sides of the ribs, the ribs being aligned in the transverse direction. In Example 1 of a Sunder patent, perforated ribs have an open area of about 10%. However, no other details are provided regarding perforations.

US Patent No. 5,603,376, entitled "Heat Exchanger for an Electrical Cabinet" issued by Hendrix, describes a heat exchanger for passive heat exchange between a waterproof, sealed electrical cabinet and the environment. Figure 2 of a Hendrix patent shows ribs 21 on the heat generation side with perforations 25 contained therein. A Hendrix patent teaches that ribs 21 are formed by folding or folding perforated sheet material. Perforations are referred to as perpendicular to the direction of the folds. Figure 2 of the Hendrix patent shows that the perforations are a single row of perforations along the sides of the ribs 21, however, no perforations are shown on the lower side where the troughs and wave crests form. In addition, the Hendrix patent does not provide ideas for the position of perforations.

In "Three-Dimensional Digital Simulation of Laminar Flow and Heat Transfer in Four Main Fins for Plate-Finned Heat Exchangers," by Y. Zhu and Y. Li, Journal of Heat Transfer, November 2008, vol. 130, 111801-1 to 8, describes a calculation based on Computational Fluid Dynamics (CFD) with respect to the performance of four samples (flat, perforated, with shifted stripes (which is another term for serrated) and wavy ribs) . The paper by Zhu and Li lists many of the major publications on compact heat exchangers that have appeared since their first introduction, and continues with the statement that, "as far as the authors know, the full three-dimensional flow and heat transfer in perforated fins have been poorly covered in the literature."

Such a statement is significant and seems to support and leads to the conclusion of the Applicants, namely that what is known in the art with respect to perforated ribs is not optimal enough.

As part of a comparison of four types of ribs, the authors of Zhu and Li performed CFD calculations on one particular illustrative geometry of a perforated rib. In order to keep reasonable the time and size of the calculation, the authors included only a minimal repeating structure, as shown in FIGS. 2a and 2b on page 2 of the document. The cross section modeled for a perforated rib is half the wavelength of the rib, which includes half of each upper and lower rib lengths and one full rib height. They, in turn, include a series of half perforations on the upper and lower parts and a series of complete perforations at the height of the ribs along the entire length of the stream. The full structure, as shown in FIG. 1D, corresponds to exactly one row of perforations along the top, bottom and side of each channel of the rib along the length of the stream, which are all aligned in the transverse direction. The diameter of the perforations is 0.8 mm, as shown in Table 1, and the distance of the perforations along the ribs seems to be approximately 1.4 mm from center to center, as can be assumed from Figs. 6C and 7C. This perforation frequency represents approximately 16% of the open area only on the sides of the plate-ribbed passages (i.e., a document from Zhu and Li does not take into account or imply perforations on the top or bottom of the ribs to determine the open area, since the perforations of the ribs on the top parts and the bottom of the ribs are covered with dividing sheets). This definition of open area is illustrated in Table 1 in the specification column. Such a pattern would be made in approximately 20% of the open area on a flat perforated sheet before being formed into ribs. It seems that this geometry represents a typical case that the authors chose to model, without a designation or idea of what they might mean preferable in relation to patterns and perforation geometries.

Thus, the one specific illustrative geometry of the perforated rib described above is only a characteristic perforated rib, which the authors used to compare with the four types of ribs (flat, perforated, strip-shifted and wavy). The pattern and geometry modeled by the authors are different from those taught in this application.

In general, the foregoing descriptions regarding perforated fins were brief in terms of details regarding the geometry of perforated fins used in plate-fin heat exchangers. And even when geometry features such as open area were cited, no idea was given about how to position the perforations and how to choose the best geometry for the perforations to achieve the best performance, so that the overall capital and operating costs of the plate-fin heat exchangers can be minimized .

It is desirable to increase efficiency and improve the performance of plate-fin heat exchangers.

In addition, it is desirable to improve the turbulence characteristics of a single-phase flow in the plate-fin passages of the plate-fin heat exchanger to improve heat transfer efficiency.

In addition, it is desirable to have a plate-fin heat exchanger that has high performance characteristics for cryogenic applications, such as those used in air separation, and for other heat transfer applications.

In addition, it is desirable to have a more efficient air separation process using a plate-fin heat exchanger that is more compact and / or more efficient than previously described.

In addition, it is desirable to have a plate-fin heat exchanger design that minimizes the size, weight and / or cost of the heat exchangers, which would lead to a more efficient and / or less expensive process for separating air per unit of product produced.

It is also desirable to have a method for assembling a plate-fin heat exchanger that uses fins with patterns and perforation geometry that provide better performance than the fins described previously and that overcomes the disadvantages of the fins described above to provide better and more advantageous results.

Summary of the invention

The described embodiments satisfy the need in the art by developing new patterns and a new geometry of rib perforations for use in plate-fin heat exchangers to maximize overall heat transfer performance under permissible pressure drop limits. The advantages of such new patterns and the new geometry of the perforations of the ribs over the previously described patterns and geometry of the ribs include: (1) a significant reduction in volume; (2) a significant increase in heat transfer efficiency; (3) a significant reduction in pressure drop losses; or (4) some reasonable combination of factors (1) - (3) so that the overall capital and operating costs of the heat exchanger system are reduced, thereby also reducing the capital and operating costs of the process that uses such a heat exchanger system.

Despite the fact that the described embodiments contained in this document are mainly aimed at the passage fins, in which the flow is more parallel to the flow channels of the ribs, ideas can also be applied to distribution ribs, which simultaneously perform some heat transfer function, and whose flow is mainly, but not exclusively, parallel to the channels of the flow of ribs. The embodiments described herein are particularly suitable for applications in which fluid streams experience heat transfer without any phase change over at least 80% of the stream length, more preferably over at least 90% of the stream length, and most preferably over 100% of the flow length in the plate-fin passages of the plate-fin heat exchanger, for example, containing channels of the ribs with patterns and perforation geometry described in this document.

In a first embodiment, a plate-fin heat exchanger is described comprising a bent rib sheet containing ribs having a height, a width and a length, the bent rib sheet being located between the first dividing sheet and the second dividing sheet; and a first side beam and a second side beam, wherein the first side beam is located between the first separation sheet and the second separation sheet and next to the first side of the bent ribbed sheet, and the second side beam is located between the first separation sheet and the second separation sheet and next to the second side a bent ribbed sheet, thereby forming at least a portion of the plate-ribbed passage; wherein the ribbed sheet contains a plurality of perforations, wherein such a plurality of perforations are arranged in parallel rows on the ribbed sheet when such a ribbed sheet is in an unbent state, such parallel rows of perforations on the ribbed sheet containing a first distance (S1) between parallel rows of perforations, a second distance (S2) between successive perforations in a parallel row of perforations, a third distance (or shift) (S3) between perforations in adjacent parallel rows of perforations, and a diameter (D) of perforations and, and the ratio (S1 / D) of the first distance between the parallel rows of perforations to the diameter of the perforations is in the range of 0.75-2.0, and the angle between the ribs and parallel rows of perforations is less than or equal to five degrees (≤5 °).

In a second embodiment, a heat exchange process between at least two streams in a plate-fin heat exchanger according to a first embodiment is described, in which at least one stream undergoes heat transfer without phase change over at least 80% of the length of the plate-fin passages, and wherein the Reynolds number of at least one stream is in the range of 800-100000, and more preferably in the range of 1000-10000.

In a third embodiment, a process for separating nitrogen, oxygen and / or argon from air by cryogenic distillation, which uses a plate-fin heat exchanger according to the first embodiment, in which at least one stream undergoes heat transfer without phase change for at least 80%, is described. the length of the plate-ribbed passages, more preferably over at least 90% of the length of the plate-ribbed passages, and most preferably over 100% of the length of the plate then-ribbed passages.

In a fourth embodiment, a method for manufacturing a plate-fin heat exchanger is described, which comprises the steps of: providing at least one perforated sheet, the at least one perforated sheet containing a plurality of perforations arranged in parallel rows, such parallel rows of perforations on the perforated sheet containing the first the distance (S1) between parallel rows of perforations, the second distance (S2) between successive perforations in a parallel row of perforations, t e is the distance (or shift) (S3) between the perforations in adjacent parallel rows of perforations, and the diameter (D) of the perforations, and the ratio (S1 / D) of the first distance between the parallel rows of perforations to the diameter of the perforations is in the range 0.75-2.0 ; bending at least one perforated sheet into ribs to form a bent perforated sheet so that the angle between the ribs and parallel rows of perforations is less than or equal to five degrees (≤5 °); the location of the first side beam near the first side of at least one bent perforated sheet, the second side beam near the second side of at least one bent perforated sheet, the first edge of the distributor near the first end of at least one bent perforated sheet, the second edge of the distributor next with a second end of at least one bent perforated sheet, a first end beam near the first rib of the distributor, and a second end beam near the w the right edge of the distributor for the formation of a preliminary plate-ribbed passage; placing a preliminary lamellar-ribbed passage from step (c) between the first dividing sheet and the second dividing sheet to thereby form a lamellar-ribbed passage between them; combining the plate-fin passage from step (d) with other plate-fin passages to form a plate-fin heat exchanger; and soldering a plate-fin heat exchanger.

Brief Description of the Drawings

The foregoing summary, as well as the following detailed description of illustrative embodiments, will be better understood when read in conjunction with the accompanying drawings. In order to illustrate embodiments, the drawings show illustrative structures; however, the invention is not limited to the specific methods and means described. In the drawings:

Figure 1 is an exploded perspective view of a main element or subassembly of a plate-fin heat exchanger with fins having a pattern and perforation geometry according to one embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating an embodiment of a perforation pattern on a flattened plate before being formed into ribs according to the present invention; FIG. and

Figure 3 is a graph illustrating the relative heat transfer performance and pressure loss of perforated ribs as a function of S1 / D with the preferred range indicated.

Detailed Description of Embodiments of the Present Invention

One embodiment of the present invention relates to plate-fin heat exchangers that comprise perforated ribs in at least a portion of the plate-fin passages, and to methods for assembling such plate-fin heat exchangers. Perforated ribs are assembled using flat perforated sheets. The formed ribs have a special relation to the pattern of perforation on a flat sheet. While some plate-fin passages have the above-mentioned ribs, other plate-fin passages can have other types of ribs, including, for example, flat, perforated, with a shifted strip or wavy type. Plate-fin heat exchangers that contain such perforated fins have particular application in cryogenic processes such as air separation, although they can also be used in other heat transfer procedures.

As can be seen in FIG. 1, the plate-fin heat exchanger of the present invention contains several plate-fin passages, some of which are formed by positioning at least one sheet 10 between the dividing sheets or plates 30, 40 of the side rails 50, 60, distribution ribs (not shown, but generally known in the art) and end beams (not shown, but generally known in the art). These plate-ribbed passages contain special patterns of perforations 20 in at least some part of such plate-ribbed passages.

Before being formed into a ribbed sheet 10, as shown in FIG. 1, the ribbed sheet 10 is a flattened sheet made of a metal such as aluminum, copper, another alloy, or any other heat-conducting material known in the art for making ribs. The tapered ribbed sheet 10, as shown in FIG. 2, contains perforations 20. The tapered sheet has special perforation patterns containing several parallel rows of perforations 100, 200, 300, each parallel row 100, 200, 300 containing perforations 1A, 1B, 1C ; 2A, 2B, 2C; and 3A, 3B, 3C. In one embodiment, the rows of perforations 1A, 1B, 1C; 2A, 2B, 2C; and 3A, 3B, 3C will be aligned in a direction that is parallel to the desired direction of the ribs when the flattened sheet is bent to form a ribbed sheet 10, as shown in FIG. 1. When the ribs are used as passage ribs, the nominal flow paths will be parallel to the direction of the perforations, as shown in FIG. 2.

As shown in FIG. 2, the perforations have a diameter (D). The distance between the parallel rows of perforations 100, 200, 300 is indicated as S1, while the distance between successive perforations (that is, between perforations 2A and 2B) in the flow direction is indicated as S2. The offset between the perforations in adjacent parallel rows 100, 200, 300 (i.e. between 2A and 3A) is designated as S3.

In one embodiment, Applicants were surprised to find that when the following parameters are held in the following ranges: (1) perforation diameters D in the range of 1 mm-4 mm; (2) open area in the range of 5% -25%; (3) an S3 / S2 ratio in the range of 0.25-0.75; (4) and an S1 / D ratio in the range of 0.75-2.0 with the most preferred range of 0.75-1.0, plate-fin heat exchangers are highly efficient and have improved performance compared to traditional heat exchangers not designed accordingly .

In the most preferred arrangement / embodiment, the fluid flow direction is parallel to the parallel rows of perforations 100, 200, 300, but in the preferred arrangement / embodiment, the fluid flow direction is in the range of five degrees (5 °) to the direction of the parallel rows of perforations 100, 200 , 300. This means that since the ribs are formed, the ribbed sheet 10 must be bent so that the angle between the folds of the ribs and such parallel rows of perforations 100, 200, 300 is less than or equal to five degrees, whereas the most preferred arrangement is in which such an angle is zero degrees (0 °).

The ribbed sheets 10 may contain perforations 20 that are circular, as shown in FIGS. 1 and 2, however, those skilled in the art will understand that non-circular perforations may also be used, including perforations in the form of ellipses, rectangles , parallelograms, and other such forms, but not limited to this.

In yet another embodiment, the arrangement of the shifted rows of perforations will be repeated every two rows, as shown in FIG. 2 (i.e., Row 100 will be shifted like Row 300, 500 (not shown), 700 (not shown), and so on) . Moreover, when the flat perforated sheets are bent into ribs in the ribbing operation, the perforation structure that is obtained on the finished ribbed sheet 10 tends to have a complex relationship due to the mechanical details of how the material flows in the rib dies. In one embodiment, the flattened sheet is folded so that the perforation patterns on the finished ribbed sheet 10 are repeated at least once every ten (10) wavelengths of the rib, and more preferably at least every five (5) wavelengths of the rib, at least at fifty percent (50%) of the plate-fin passages of the heat exchanger containing such perforated fins, more preferably at least eighty percent (80%) of the plate-fin passages and most preferably at one hundred percent (100%) lamellar-ribbed passages.

In a further embodiment, the surface texture may be applied to the perforated sheets before folding the material into fins, as described in US Patent No. 6,834,515 B2, entitled "Plate-Finned Surface Heat Exchangers" issued by Sunder and others, which is fully incorporated herein. link. Alternatively, a surface texture can be created in the process of creating edges from flat perforated sheets.

The embodiments described herein are suitable for plate-fin heat exchangers in which at least a portion of the fins has a height in the range of 0.25 inches to 1 inch (0.635 centimeters to 2.54 centimeters), more preferably in the range of 0.40 inches - 0.75 inches (1.016 centimeters - 1.905 centimeters) and most preferably in the range of 0.5 inches - 0.6 inches (1.27 centimeters - 1.524 centimeters). Embodiments are preferably applied when the fluid flow conditions in such plate-fin passages are in a transition state between a laminar and turbulent state or in a turbulent state. This can be expressed as a Reynolds Number Range of 800-100000, and more preferably a range of 1000-10000. Reynolds number is calculated as follows:

Re = pVD / μ,

Where

Re = Reynolds number;

p = fluid density;

V = fluid velocity;

μ = fluid viscosity;

D = 4A / P;

A = cross-sectional area of the fluid stream; and

P = perimeter of fluid flow.

For plate-finned passages, it is common to calculate the hydraulic diameter D based on individual plate-finned passages, and these calculations are based on the use of base metal sheets without adjusting the perforations for their contribution to A (cross-sectional area of the fluid flow) and P (flow perimeter fluid).

Embodiments of the present invention are of considerable value since plate-fin heat exchangers can be made more compact with respect to conventional plate-fin heat exchangers, thereby saving jointly the capital and operating costs of a plant, such as an air separation plant.

EXAMPLE 1

To better understand the effect of perforations in rib geometry, several sample problems have been solved using Computational Fluid Dynamics (CFD). When using this technique, it is common to limit the calculation to some repeating structure to limit the size of the problem calculation. But when trying to measure the effect of specific patterns of perforation, the overall geometry of the heat exchanger is very complex, even if the problem is limited to a single subchannel in the plate-ribbed passages. For this reason, a different type of approximation was used.

In most plate-fin heat exchangers, the secondary surface area tends to be the dominant part of the total area. As noted earlier, this is the area represented by the legs of the ribs that overlap and separate the dividing sheets or plates 30, 40, which represent the area of the primary surface. To understand the effect of the location of perforations, the characteristic periodic area of two endless parallel plates was simulated to measure heat transfer and pressure losses that occur when air flows between them. The general pattern of perforations on a flattened sheet is illustrated in FIG.

Example 1 describes fins that are used for heat transfer and / or distribution, in which, as previously stated, the flow direction is generally parallel to the direction of the rib, as indicated in FIG. 2.

A number of illustrative cases were resolved using CFDs in which different distances (S1, S2 and S3) were changed while keeping the diameter (D) of the perforations and the total open area constant. In particular, the distances S1 and S2 were changed simultaneously, while the shift S3 was set equal to half the distance S2. In these illustrative cases, there was only one independent parameter, and the results are shown in Table 1 and illustrated in FIG. 3.

Table 1 Parameter S1 / S2 S1 / D Relative heat transfer Relative pressure loss Case 1 0,037 0.5417 1.2626 1.2140 Case 2 0,071 0.7500 1.2469 1,1806 Case 3 0.127 1,0000 1.2465 1,1789 Case 4 0.224 1,3292 1,2162 1,1689 Case 5 0.348 1.6583 1,1951 1,1554

Case 6 0,500 1.9875 1,1881 1,1505 Case 7 0.679 2,3167 1,1347 1,1031 Case 8 0.886 2,6458 1,0632 1,0483 Case 9 1,120 2.9750 1,0000 1,0000

Illustrative calculations show the relative values of pressure loss and heat transfer rates, which are achieved purely by changing the pattern of perforations. Illustrative data were plotted after scaling with respect to values that occur when the ratio of distance to perforation size was approximately 3. As this ratio decreases to approximately 2, a significant improvement in heat transfer occurs. As noted in Table 1, the increase in heat transfer is higher than the increase in the corresponding pressure loss. Thus, a heat exchanger designed with a ratio of 2 can be shorter by a factor of about 1.2 compared with a heat exchanger designed with a ratio of 3, while the total pressure loss will also be lower. This represents a significant reduction in length and, through this, volume. If the ratio decreases below 2, the improvement is repeated, and especially good values are obtained between the ratio values between 0.75 and 1. In this ratio range, there is an improvement in heat transfer by a factor of about 1.25. The required length or volume will be the inverse of this ratio, namely 0.80 or eighty percent (80%). This represents a significant reduction in size by twenty percent (20%), while pressure loss will also be reduced by a ratio of 1.18 / 1.25, which is 0.94 or ninety-four percent (94%). Thus, there may be a twenty percent (20%) decrease in length or volume, while there is also a six percent (6%) decrease in pressure loss.

These are significant improvements that can be achieved by arranging the positions of the perforations, as described in this document, which was not known or described previously. In fact, either through clearly expressed statements, or through subtexts, or illustrations, some of the preceding descriptions gave ideas leading away from such arrangements. As shown in FIG. 3, a ratio range of 0.75 to 2.0 is preferred, with a range of 0.75 to 1.0 being particularly preferred.

EXAMPLE 2

Example 2 shows an illustrative improvement obtained using the ideas contained in this document. As noted earlier, in traditional ideas regarding perforated fins in plate-fin heat exchangers, preferred geometry or patterns of perforation, as described herein, were not discussed. However, in the CFD document, authored by Zhu and others, cited earlier, the effect of a specific perforated rib was studied compared to other forms of ribs such as flat, serrated, and wavy ribs. The present example was formed by applying the perforation pattern used in the CFD document by Zhu and others in the same manner as described in Example 1.

The parameters of the perforation pattern on flat sheets before bending into the ribs are as follows: perforation diameter (D) = 0.8 mm; open area = 20%; S1 = 1.81 mm; S2 = 1.39 mm; and S3 = 0. The calculated relative performance of the heat exchanger using such prior art fins is shown in Table 2.

table 2 Parameter CFD Document Described Illustrative Embodiment Diameter of perforation, mm 0.8 2,4 Open area,% twenty 10 S1 mm 1.81 2,4 S2 mm 1.39 18.96 S3 mm 0,0 9.48 S1 / D 2.26 1,0 S3 / S2 0,0 0.5 Relative heat transfer coefficient 1.00 1.26 Relative pressure drop 1.00 1.26 Relative heat exchanger length 1.00 0.79 Relative heat exchanger volume 1.00 0.79 Relative pressure loss in the heat exchanger 1.00 1.00

As shown in Table 2, since the Relative heat transfer coefficient and Relative pressure drop of the described illustrative embodiment are 26% higher than that of the heat exchanger according to the CFD document, the heat exchanger designed according to the ideas of the described illustrative embodiment may have a shorter relative length (21% smaller) and lower relative volume (21% less) compared to a heat exchanger designed on the basis of the ideas of the CFD document, both heat exchangers having the same or adayuschie heat transfer capacity and pressure drop. This is a significant advantage for using ribs made according to the ideas of the described illustrative embodiment, compared with the ideas of the CFD document.

Although the features of the present invention have been described in connection with the preferred embodiments in the various drawings, it should be understood that other similar embodiments may be used or modifications or additions to the described embodiment may be made to carry out the same function of the present invention without departing from him. For example, the following features should also be understood as being part of this description:

Feature 1. Plate-fin heat exchanger containing:

a folded ribbed sheet comprising ribs having a height, width and length, wherein the folded ribbed sheet is located between the first dividing sheet and the second dividing sheet; and

a first side beam and a second side beam, wherein the first side beam is located between the first separation sheet and the second separation sheet and next to the first side of the bent ribbed sheet, and the second side beam is located between the first separation sheet and the second separation sheet and next to the second side of the bent ribbed sheet, thereby forming at least a portion of the plate-ribbed passage;

wherein the ribbed sheet contains a plurality of perforations, wherein such a plurality of perforations are arranged in parallel rows on the ribbed sheet when such a ribbed sheet is in an unbent state, such parallel rows of perforations on the ribbed sheet containing a first distance (S1) between parallel rows of perforations, a second distance (S2) between successive perforations in a parallel row of perforations, a third distance (or shift) (S3) between perforations in adjacent parallel rows of perforations, and a diameter (D) of perforations and, and the ratio (S1 / D) of the first distance between the parallel rows of perforations to the diameter of the perforations is in the range of 0.75-2.0, and the angle between the ribs and parallel rows of perforations is less than or equal to five degrees (≤5 °).

Feature 2. A plate-fin heat exchanger according to Feature 1, wherein the angle between the ribs and parallel rows of perforations is zero degrees (0 °).

Feature 3. The plate-fin heat exchanger according to Feature 1 or Feature 2, in which the ratio (S1 / D) of the first distance between the parallel rows of perforations to the diameter of the perforations lies in the range 0.75-1.0.

Feature 4. The plate-fin heat exchanger according to any one of Features 1-3, wherein the ratio of the third distance (or shear) (S3) between perforations in adjacent parallel rows of perforations and the second distance (S2) between consecutive perforations in a parallel row of perforations lies in the range 0.25-0.75.

Feature 5. The plate-fin heat exchanger according to any one of Features 1 to 4, in which 5% -25% of the area of the bent ribbed sheet in an unbent state is occupied by perforations.

Feature 6. The plate-fin heat exchanger according to any one of Features 1-5, wherein the diameter (D) of the perforation is in the range of 1 mm to 4 mm.

Feature 7. A plate-fin heat exchanger according to any one of Features 1 to 6, wherein the perforations are circular.

Feature 8. A plate-fin heat exchanger according to any one of Features 1 to 6, wherein the perforations are in the form of ellipses, rectangles or parallelograms.

Feature 9. The plate-fin heat exchanger according to any one of Features 1-8, wherein adjacent parallel rows of perforations are shifted alternately so that the position of the parallel rows of perforations is repeated every second row of perforations.

Feature 10. The plate-fin heat exchanger according to any one of Features 1-8, wherein adjacent parallel rows of perforations are shifted so that the position of the parallel rows of perforations on the ribs of the bent ribbed sheet is accurately repeated at least once every 10 wavelengths of the ribs and more preferably at least once every 5 wavelengths of the ribs in at least 50% of the plate-fin passages of the heat exchanger containing such perforated ribs, more preferably at least 80% of the plate-fin rib moves and most preferably 100% plate-fin passages.

Feature 11. The plate-fin heat exchanger according to any one of Features 1-10, wherein the folded ribbed sheet contains a surface texture.

Feature 12. A plate-fin heat exchanger according to any one of Features 1 to 11, wherein the rib height is in the range of 0.25 inches to 1 inch (0.635 centimeters to 2.54 centimeters), more preferably in the range of 0.4 inches to 0, 75 inches (1.016 centimeters - 1.905 centimeters) and most preferably in the range of 0.5 inches - 0.6 inches (1.27 centimeters - 1.524 centimeters).

Feature 13. The plate-fin heat exchanger according to any one of Features 1-12, wherein the bent ribbed sheet is a heat transfer rib or distributor rib.

Feature 14. The plate-fin heat exchanger according to any one of Features 1 to 13, wherein the plate-fin passages are adapted to receive a fluid stream, and in which the fluid stream undergoes heat transfer without phase change for at least 80%, more preferably over at least 90%, and most preferably over 100% of the length of the plate-ribbed passages.

Feature 15. The heat exchange process between at least two streams in a plate-fin heat exchanger designed in accordance with any one of Features 1 to 13, wherein at least one stream undergoes heat transfer without phase change over at least 80% of the length of the plate-fin passages and in which the Reynolds number of the at least one stream lies in the range of 800-100000, and more preferably in the range of 1000-10000.

Feature 16. The process of separating nitrogen, oxygen and / or argon from air through cryogenic distillation, which uses a plate-fin heat exchanger according to any one of Features 1 to 13, in which at least one stream undergoes heat transfer without phase change for at least 80 % of the length of the plate-ribbed passages, more preferably over at least 90% of the length of the plate-ribbed passages, and most preferably over 100% of the length of the plate-ribbed passages.

Feature 17. A method of manufacturing a plate-fin heat exchanger, which contains the steps:

(a) providing at least one perforated sheet, wherein at least one perforated sheet comprises a plurality of perforations arranged in parallel rows, such parallel rows of perforations on the perforated sheet comprising a first distance (S1) between parallel rows of perforations, a second distance (S2 ) between consecutive perforations in a parallel row of perforations, the third distance (or shift) (S3) between perforations in adjacent parallel rows of perforations, and the diameter (D) of the perforations, with the ratio (S1 / D) of the first distance between parallel rows of perforations to the diameter of the perforation is in the range of 0.75-2.0;

(b) bending at least one perforated sheet into ribs to form a bent perforated sheet so that the angle between the ribs and parallel rows of perforations is less than or equal to five degrees (≤5 °);

(c) the location of the first side beam near the first side of at least one bent perforated sheet, the second side beam near the second side of at least one bent perforated sheet, the first edge of the distributor near the first end of at least one bent perforated sheet, the second ribs of the distributor near the second end of at least one bent perforated sheet, the first end beam next to the first rib of the distributor, and the second end beam next to the second rib of the distributor for the formation of a preliminary plate-ribbed passage;

(d) placing a preliminary lamellar-ribbed passage from step (c) between the first dividing sheet and the second dividing sheet to thereby form a lamellar-ribbed passage between them;

(e) combining the plate-fin passage from step (d) with other plate-fin passages to form a plate-fin heat exchanger; and

(f) brazing a plate fin heat exchanger.

Feature 18. A method of manufacturing a plate-fin heat exchanger according to Feature 17, further comprising applying a surface texture to at least one perforated sheet before folding at least one perforated sheet in step (b).

Therefore, the claimed invention should not be limited to any single embodiment or feature, but rather should be construed within the spirit and scope of the attached claims.

Claims (18)

1. A plate-fin heat exchanger containing:
a folded ribbed sheet comprising ribs having a height, width and length, wherein the folded ribbed sheet is located between the first dividing sheet and the second dividing sheet; and
a first side beam and a second side beam, wherein the first side beam is located between the first separation sheet and the second separation sheet and next to the first side of the bent ribbed sheet, and the second side beam is located between the first separation sheet and the second separation sheet and next to the second side of the bent ribbed sheet, thereby forming at least a portion of the plate-ribbed passage;
moreover, the ribbed sheet contains many perforations, and such many perforations are located on the ribbed sheet in parallel rows, when such a ribbed sheet is in an unbent state, and such parallel rows of perforations on the ribbed sheet contain a first distance between parallel rows of perforations (S1), the second distance between consecutive perforations in a parallel row of perforations (S2), the third distance (or shift) between perforations in adjacent parallel rows of perforations (S3), and the diameter (D) of the perforations, moreover, the ratio of the first distance between the parallel rows of perforations to the diameter of the perforations (S1 / D) is in the range of 0.75-2.0, and the angle between the ribs and parallel rows of perforations is less than or equal to five degrees (≤5 °). 2. The plate-fin heat exchanger according to claim 1, in which the angle between the ribs and parallel rows of perforations is zero degrees (0 °). 3. The plate-fin heat exchanger according to claim 1, in which the ratio of the first distance between the parallel rows of perforations to the diameter of the perforations (S1 / D) lies in the range of 0.75-1.0. 4. The plate-fin heat exchanger according to claim 1, in which the ratio of the third distance (or shear) between the perforations in adjacent parallel rows of perforations (S3) and the second distance between successive perforations in a parallel row of perforations (S2) lies in the range 0.25- 0.75. 5. The plate-fin heat exchanger according to claim 1, in which 5-25% of the area of the bent ribbed sheet in an unbent state is occupied by perforations. 6. The plate-fin heat exchanger according to claim 1, in which the diameter (D) of the perforation lies in the range of 1 mm to 4 mm 7. The plate-fin heat exchanger according to claim 1, wherein the perforations are circular. 8. The plate-fin heat exchanger according to claim 1, in which the perforations are in the form of ellipses, rectangles or parallelograms. 9. The plate-fin heat exchanger according to claim 1, in which adjacent parallel rows of perforations are shifted alternately so that the position of the parallel rows of perforations is repeated every second row of perforations. 10. The plate-fin heat exchanger according to claim 1, wherein the adjacent parallel rows of perforations are shifted so that the position of the parallel rows of perforations on the ribs of the bent ribbed sheet is precisely repeated at least once every 10 wavelengths of the ribs and more preferably at least once every 5 wavelengths of the ribs in at least 50% of the plate-ribbed passages of the heat exchanger containing such perforated ribs, more preferably in at least 80% of the plate-ribbed passages and most preferably in 100% lamellar-ribbed passages. 11. The plate-fin heat exchanger according to claim 1, in which the bent ribbed sheet contains a surface texture. 12. The plate-fin heat exchanger according to claim 1, wherein the fin height is in the range of 0.25 inches to 1 inch, more preferably in the range of 0.4 inches to 0.75 inches, and most preferably in the range of 0.5 inches to 0 , 6 inches. 13. The plate-fin heat exchanger according to claim 1, in which the bent ribbed sheet is a heat transfer rib or distributor rib. 14. The plate-fin heat exchanger according to claim 1, wherein the plate-fin passages are adapted to receive a fluid stream, and wherein the fluid stream undergoes heat transfer without phase change for at least 80%, more preferably for at least 90% and most preferably over 100% of the length of the plate-ribbed passages. 15. The method of heat transfer between at least two streams in a plate-fin heat exchanger, designed according to claim 1, in which at least one stream is subjected to heat transfer without phase change for at least 80% of the length of the plate-fin passages and in which the Number The Reynolds of at least one stream lies in the range of 800-100000, and more preferably in the range of 1000-10000. 16. The method of separating nitrogen, oxygen and / or argon from air by cryogenic distillation, which uses a plate-fin heat exchanger according to claim 1, in which at least one stream undergoes heat transfer without phase change for at least 80% of the length of the plate ribbed passages, more preferably over at least 90% of the length of the plate-ribbed passages, and most preferably over 100% of the length of the plate-ribbed passages. 17. A method of manufacturing a plate-fin heat exchanger, which contains the steps:
(a) providing at least one perforated sheet, the at least one perforated sheet comprising a plurality of perforations arranged in parallel rows, such parallel rows of perforations on the perforated sheet containing a first distance between parallel rows of perforations (S1), a second distance between consecutive perforations in a parallel row of perforations (S2), the third distance (or shift) between perforations in adjacent parallel rows of perforations (S3), and the diameter (D) of the perforations, and the ratio the first distance between the parallel rows of perforations to the diameter of the perforations (S1 / D) is in the range of 0.75-2.0;
(b) bending said at least one perforated sheet into ribs to form a bent perforated sheet so that the angle between the ribs and parallel rows of perforations is less than or equal to five degrees (≤5 °);
(c) the location of the first side beam near the first side of at least one bent perforated sheet, the second side beam near the second side of at least one bent perforated sheet, the first edge of the distributor near the first end of at least one bent perforated sheet, the second ribs of the distributor near the second end of at least one bent perforated sheet, the first end beam next to the first rib of the distributor and the second end beam next to torym rib spreader to form a preliminary plate fin passage;
(d) placing a preliminary lamellar-ribbed passage from step (c) between the first dividing sheet and the second dividing sheet to thereby form a lamellar-ribbed passage between them;
(e) combining the plate-fin passage from step (d) with other plate-fin passages to form a plate-fin heat exchanger; and
(f) brazing a plate fin heat exchanger. 18. A method of manufacturing a plate-fin heat exchanger according to 17, further comprising applying a surface texture to at least one perforated sheet before folding at least one perforated sheet in step (b).

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