KR20110138179A - Fin and tube heat exchanger - Google Patents

Abstract

PURPOSE: A fin and tube exchanger is provided to reduce the loss of energy and increase heat transfer rate per unit pressure loss. CONSTITUTION: A fin and tube exchanger(210) comprises a plurality of tubes(220) and a plurality of fins(230). The tubes comprise a first set of tubes(240) and a second set of tubes(250), and the tube in the first set comprises an offset position(305) to the tube in the second set. The first tube set comprises a first row of tubes(260) and a second row of tubes(270). The tubes in the first and second rows are comprise an inline position(275) to a flow(280) across the first row of tubes and the second row of tubes. The fin is located on the tube.

Description

Fin and Tube Heat Exchanger {FIN AND TUBE HEAT EXCHANGER}

FIELD OF THE INVENTION The present invention relates generally to fin and tube heat exchangers, and in particular, to a compact, arranged in a semi-staggered manner, with rectangular fins and vortex generators to maximize heat exchange while minimizing pressure loss. Fin and tube heat exchanger.

A wide variety of fin and tube type heat exchangers and similar structures are sold. One of the main design goals of the structure of fin and tube type heat exchangers is to maximize heat transfer while minimizing pressure loss. Generally speaking, the degree of pressure loss can be directly related to the operating cost and overall energy loss and the efficiency of the heat exchanger and its use.

One example of a known fin and tube heat exchanger design involves the use of tube bundles with tightly-spaced and spiral-wound circular fins. However, the use of such circular fins generally reduces the speed of air passing therethrough, so that the bypass flow and wake region can be relatively large and the heat transfer coefficient can be small. Moreover, the bypass flow can exacerbate the heat transfer coefficient as well as fouling problems for the fins and interspaces. Circular fins can also limit fin spacing and thus limit the useful total surface area per tube.

Continuous flat fins and substantially square fins are also used. Such continuous flat fins tend to have a lower pressure loss per unit heat transfer than conventional round fins. Continuous flat fins are used to make very compact and efficient heat exchangers, while continuous flat fins and square fins are used for heat recovery steam generators, or fins made of generally large heat transfer areas, large diameter tubes, and / or steel. It is not generally adopted for large power generation equipment, such as similar types of equipment required.

Known tube bundle arrangements generally consist of an inline or staggered arrangement. Stagger arrangements are generally preferred over inline arrangements because they provide a high heat transfer coefficient with less bypass flow. However, the pressure loss of this stagger arrangement can be relatively high due to the profile drag caused by the tube. The inline arrangement places each tube downstream of the preceding tube to reduce the overall cross sectional resistance. Dalgal and elliptical tubes and fins are also used to reduce cross sectional resistance and pressure loss, but such tubes generally do not withstand the very high pressures typically found in power generation equipment.

Various techniques, including, for example, the use of louvers, corrugations, undulations, serrations, and winglet vortex generators, improve heat transfer on the fin surface. Is being studied to make. Most of these improvements are used for continuous fin heat exchangers, and dimples and serrations can be used for individual round fins. Many of these refinements can be combined for a given pin or set of pins.

Therefore, there is a need for an improved compact fin and tube heat exchanger that can increase the heat transfer rate per unit pressure loss to provide a compact and inexpensive heat exchanger with low energy loss and low overall life cycle cost. Such fin and tube heat exchangers may be used in a variety of gas-liquid or gas-vapor heat transfer applications, and particularly preferably in power generation operations, and the like.

Accordingly, the present invention provides fin and tube heat exchangers. Fins and tube heat exchangers may include a plurality of tubes and a plurality of fins located on each tube. The tube includes a first set of tubes and a second set of tubes, wherein the first set of tubes includes an offset position compared to the second set of tubes.

The invention further provides fin and tube heat exchangers. Fin and tube heat exchangers can include a plurality of tubes and a plurality of rectangular fins located on each tube. The rectangular pin can include one or more vortex generators on the rectangular pin.

The invention further provides fin and tube heat exchangers. The fin and tube heat exchanger may comprise a plurality of tubes consisting of a first set of tubes having an offset position compared to a second set of tubes, and a plurality of rectangular fins located on each tube. The rectangular pin may include a number of vortex generators on the rectangular pin.

These and other features of the present invention will become apparent to those skilled in the art upon reading the following detailed description in conjunction with the several figures and the appended claims.

1 is a schematic diagram of a gas turbine engine,
2 is a partial perspective view of a semi-staggered fin and tube heat exchanger,
3 is a perspective view of an individual rectangular flat fin having a vortex generator that may be used with the semi-stagger fin and tube heat exchanger of FIG.

Referring now to the drawings, like numerals refer to like elements throughout the several views, and FIG. 1 shows a schematic diagram of a gas turbine engine 100 described herein. The gas turbine engine 100 may include a compressor 110. Compressor 110 compresses inlet air stream 120. The compressor 110 delivers the compressed air stream 120 to the combustor 130. The gas turbine engine 100 combustor 130 mixes the compressed air stream 120 with the compressed fuel stream 140 and ignites the mixture to produce the combustion gas stream 150. Although only one combustor 130 is shown, the gas turbine engine 100 may include multiple combustors 130.

Combustion gas flow 150 is also delivered to turbine 160. Combustion gas flow 150 drives turbine 160 to produce mechanical operation through rotation of turbine rotor 170. Mechanical operation generated in the turbine 160 drives an external load such as the compressor 110, the generator 180, and the like through the turbine rotor 170.

The spent combustion gas stream 150 may then be passed to a heat recovery steam generator 190 or other type of heat exchanger. The spent combustion gas stream 150 to the heat recovery steam generator 190 may heat the passing vapor stream 200 for use in steam turbines, fuel preheaters, and / or other types of operation. Combustion gas stream 150 is then discharged or otherwise processed.

The gas turbine engine 100 may utilize natural gas, various types of new gas, and other types of fuel. The gas turbine engine 100 may or may not be any of a variety of turbines provided by General Electric Company, Schenectady, NY, USA. The gas turbine engine 100 may have a different structure and may use other types of components. Other types of gas turbine engines may also be used here. A plurality of gas turbine engines 100, other types of turbines, and other types of power generation equipment may be used together herein.

Generally speaking, the heat recovery steam generator 190 may be a non-contact heat exchanger, which heats the feed water for the steam generation process by the waste stream of the spent combustion gas 150. The heat recovery steam generator 190 may be a large duct using a tube bundle inserted therein, such that the water is heated with steam as the combustion gas stream 150 passes through the duct. Other heat recovery steam generator structures and other types of heat exchangers can be used here.

2 shows a portion of the semi-staggered fin and tube heat exchanger 210 described herein. The semi-staggered fin and tube heat exchanger 210 may be used as part of the heat recovery steam generator 190, or may be used for any type of heat exchanger device.

Semi-staggered fin and tube heat exchanger 210 includes a plurality of tubes 220 protruding therethrough, and a plurality of fins 230 are located on the tubes (for clarity, in FIG. 2 Only one protruding tube 220 is shown). Any number of tubes 220 and fins 230 can be used here. The semi-staggered fin and tube heat exchanger 210 may be relatively compact compared to conventional fin and tube heat exchangers, but may have any size, shape, and / or structure desired.

The semi-staggered fin and tube heat exchanger 210 may include a tube 220 positioned in a staggered relationship. In particular, the tubes 220 of the first set 240 can be staggered (eg, staggered) or offset from the tubes 220 of the second set 250. The tubes 220 of the first set 240 may include a first row 260 and a second row 270, the tubes 220 in-line position 275 relative to the air stream 280 passing therethrough. Has The tube 220 of the second set 250 can include a third row 290 and a fourth row 300, the tube 220 also having an inline position 275. While pairs of tubes 220 are shown in first set 240 and second set 250, any number of rows 260, 270 and 290, 300 may be combined with any number of tubes 220. Can be used. The first set 240 and the second set 250 may have offset positions 305 relative to each other to form a semi-stagger relationship. The offset position 305 may be about half of the transverse spacing of the pins 230. Other types of offsets, spacings, and structures can be used here.

As shown in FIGS. 2 and 3, the fin 230 of the semi-staggered fin and tube heat exchanger 210 may be in the form of a substantially rectangular fin 310. Each rectangular fin 310 may have a number of vortex generators 320 located on a corner. In this example, the vortex generator 320 may have a substantially triangular shape 330. Moreover, opposite pairs of vortex generators 320 may have an upward angle 340, and other opposite pairs of vortex generators 320 may have a downward angle 350. Any number of vortex generators 320 with other sizes, structures, and / or angles may be used herein.

The rectangular fins 310 may have a substantially eccentric position 360 with respect to each tube 220. As a result, the distance between the rows 260, 270 and 290, 300 of each set 240, 250 can be minimized (thus, the distance between the tubes 220 of each set 240, 250 can be increased). Can be). Other types of positioning may be used here. There may be a gap 370 between each rectangular fin 310. The size and shape of the gap 370 may vary. The gap 370 may be sized such that the rectangular fin 310 acts as a substantially continuous fin in use.

As mentioned above, in-line tube arrangements generally have the advantage of low pressure loss, and stagger arrangements generally induce good heat transfer. Thus, in use, the semi-staggered fin and tube heat exchanger 210 described herein combines the advantages of both positioning. Specifically in this example, the second column 270 of the first set 240 and the fourth column 300 of the second set 250 are generally the first column 260 of the first set 240. And wake in the third row 290 of the second set 250, respectively. Thus, such staggered or offset positions 305 are inline rows of tubes 220, in particular based in part on eccentric positions 360 of fins 230 of rows 260, 270 and 290, 300. Given a relatively small gap between 260, 270 and 290, 300, it reduces the aerodynamic cross-sectional resistance that bears a portion of the pressure loss. Likewise, staggering first set 240 and second set 250 of tubes 220 may generate or improve horseshoe and wake vortices to improve heat transfer on fins 230.

The rectangular fins 310 of the semi-staggered fin and tube heat exchanger 210 are mostly continuous flat fins to enable dense fin spacing without altering the flow field or generating much or to some degree of bypass flow. Acts as. The size of the gap 370 between the rectangular fins 310 allows for the installation of individual tubes 220 into a compact tube bundle while allowing much less bypass flow, for example, compared to the circular fins and tube bundles described above. do. Specifically, the gap 370 may be small enough to form a semi-continuous plate fin, but may be large enough to substantially dismantle the boundary layer. Thus, the gap 370 may perform some mixing and boundary layer breakage between the fins 310, which may have a positive effect on heat transfer performance.

The triangular tip 330 of the vortex generator 320 of the semi-staggered fin and tube heat exchanger 210 also generates or improves horseshoe and / or wake-like vortex for the stagger set 240, 250. Let's do it. Longitudinal and other types of vortices can also occur. Such vortices tend to improve the overall heat transfer on the rectangular fins 310. By alternately using the upward and downward angles 340 and 350, it is possible to redirect the impinging flows on the upper and lower fins 310, respectively. This flow also improves longitudinal vortices and further enhances heat transfer while dismantling the boundary layer.

Thus, the semi-staggered fin and tube heat exchanger 210 provides an offset position 305 to the stagger set 240, 250 of the tube 220. Each tube 220 has a plurality of rectangular fins 310 with a plurality of vortex generators 320 thereon. Pin 310 may include an eccentric position 360 to minimize the distance between rows 260, 270 and 290, 300 of each set 240, 250, and at the same time, pin 210 may It also has a small gap 370 in between. Thus, the semi-staggered fin and tube heat exchanger 210 has less pressure loss and better heat transfer per tube than conventional fin and tube designs. The semi-staggered fin and tube heat exchanger 210 may also be more compact with less tube heat and lower operating costs for a given total duty.

Thus, the semi-staggered fin and tube heat exchanger 210 can be used for a variety of gas-liquid or gas-vapor heat transfer applications, and in particular, for power generation operations and the like. Smaller, better and cheaper heat exchangers generally provide an energy system with a smaller footprint and lower operating costs.

The foregoing is relevant only to the preferred embodiments of the present invention, and therefore, numerous changes and modifications may be made by those skilled in the art without departing from the general spirit and scope of the invention as defined by the following claims and their equivalents. It should be understood that there is.

100 gas turbine engine 110 compressor 120 air flow
130: combustor 140: fuel flow 150: combustion gas flow
160: turbine 170: rotor 180: generator
190: heat recovery steam generator 200: steam flow
210: semi-staggered fin and tube heat exchanger
220: tube 230: pin 240: first set
250: second set 260: first column 270: second column
275: in-line position 280: air flow 290: third column
300: fourth column 305: offset position 310: rectangular pin
320: vortex generator 330: triangular shape portion 340: upward angle
350: downward angle 360: eccentric position 370: gap

Claims (12)

In the fin and tube heat exchanger 210,
A plurality of tubes 220,
A plurality of fins 230 positioned on each of the plurality of tubes 220,
The plurality of tubes 220 includes a first set of tubes 240 and a second set of tubes 250,
The first set of tubes 240 includes an offset position 305 compared to the second set of tubes 250.
Fin and tube heat exchanger. The method of claim 1,
The first set of tubes 240 includes a first row of tubes 260 and a second row of tubes 270.
Fin and tube heat exchanger. The method of claim 2,
The first row of tubes 260 and the second row of tubes 270 include inline positions 275 relative to the flow 280 across the first row of tubes 260 and the second row of tubes 270.
Fin and tube heat exchanger. The method of claim 2,
The second set of tubes 250 includes a third row of tubes 290 and a fourth row of tubes 300.
Fin and tube heat exchanger. The method of claim 1,
The offset position 305 includes approximately half of the length of the pin 230.
Fin and tube heat exchanger. The method of claim 1,
The plurality of pins 230 includes a plurality of rectangular pins 310.
Fin and tube heat exchanger. The method of claim 1,
The plurality of pins 230 includes a plurality of vortex generators 320 thereon.
Fin and tube heat exchanger. The method of claim 7, wherein
The plurality of vortex generators 320 includes a substantially triangular shape 330
Fin and tube heat exchanger. The method of claim 7, wherein
The plurality of vortex generators 320 has one or more upward angles 340 and one or more downward angles 350.
Fin and tube heat exchanger. The method of claim 1,
The plurality of fins 230 includes a substantial eccentric position 360 for each tube 220.
Fin and tube heat exchanger. The method of claim 1,
The first plurality of fins 230 positioned on the first tube 220 and the second plurality of fins 230 positioned on the second tube 220 include a gap 370 therebetween.
Fin and tube heat exchanger. The method of claim 1,
The fin and tube heat exchanger 210 includes a heat recovery steam generator 190.
Fin and tube heat exchanger.

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