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Fin and tube heat exchanger / General Electric Company




Title: Fin and tube heat exchanger.
Abstract: The present application provides a fin and tube heat exchanger. The fin and tube heat exchanger may include a number of tubes with a number of substantially spirally wound circular fins positioned on each of the tubes. The tubes may include a first set of tubes including a plurality of tube pairs each including a tube in a first row of tubes and a tube in a second row of tubes of the first set of tubes. The tubes may further include a second set of tubes including a plurality of tube pairs including a tube in a third row of tubes and a tube in a fourth row of tubes of the second set of tubes. The first set of tubes further including a transverse offset position as compared to the second set of tubes. ...


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USPTO Applicaton #: #20120305227
Inventors: Sebastian Walter Freund, William Joseph Antel, Jr.


The Patent Description & Claims data below is from USPTO Patent Application 20120305227, Fin and tube heat exchanger.

BACKGROUND

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The present application relates generally to fin and tube heat exchangers and more particularly relates to a semi-staggered arranged compact fin and tube heat exchanger with substantially spirally wound circular fins so as to maximize heat transfer while minimizing the pressure loss therethrough.

In heat exchange applications that have a high mass flux and limited frontal area it is advantageous to utilize a design with a low-pressure drop but that maintains a relatively high heat transfer. A broad variety of fin and tube type heat exchangers and similar structures are commercially available and suitable for use in the above described heat exchange application. One of the main design goals in the construction of fin and tube type heat exchangers focuses on maximizing heat transfer while minimizing the pressure loss therethrough. Generally described, the extent of the pressure loss may be directly related to the operating costs and the overall energy losses and efficiency of the heat exchanger and its use.

When designing a heat exchanger, a large fraction of the pressure loss for a finned tube is due to profile drag. Unlike skin friction on the fin surface, profile drag has little benefit for the heat transfer. To address this profile drag, known tube bundle arrangements generally are configured either in an in-line or a staggered alignment. One example of known fin and tube heat exchanger designs includes the use of in-line tube bundles with densely-spaced and spirally-wound circular fins. In an in-line arrangement, each tube is configured in the wake of the preceding tube so as to lower the overall drag. The use of such in-line arrangement of circular fins, however, may cause relatively large bypass flows, wake regions, and lower heat transfer coefficients because of the generally reduced air velocity therethrough. Moreover, the bypass flow may exacerbate fouling problems about the fins and the spaces therebetween as well as depress the heat transfer coefficients. In-line arrangements, with low velocity between the tubes, have weak wake regions and lower pressure loss. In addition, the heat transfer coefficient on the fins as well as on the tubes is lower, since a strong bypass flow exists, as compared to a staggered arrangement where stronger flow mixing and less bypassing of the finned area occurs due to a transverse offset of a tube relative to a preceding tube. The staggered arrangement generally may be favored as such an arrangement gives a higher heat transfer coefficient with somewhat less bypass flow as compared to an in-line arrangement. The pressure loss of such a staggered arrangement, however, may be relatively high due to profile drag caused by the tubes.

Oval and elliptical shaped tubes and fins also have been used to reduce drag and pressure losses, but such tubes generally may not withstand the very high pressures found in some power plant cycles. Oval tubes too are known to have small wake regions and lower profile drag than circular tubes and hence lower pressure loss. Finned tubes having such an oval profile have a wide radius that is oriented parallel to the flow. Thus the profile drag due to the tube itself is low. The heat transfer coefficient on oval finned tubes is, enhanced by horseshow and wake vortices, slightly higher than on circular tubes. However, oval tubes have much lower pressure ratings, are more difficult to manufacture than circular tubes and are susceptible to deformation from pressure effects. To alleviate this problem, manufacturers have incorporated a vertical strut in the center of the tube for stability.

In heat exchange applications that have a high mass flux and limited frontal area it is advantageous to utilize a design with a low-pressure drop, but that maintains a relatively high heat transfer. An example of this application would be an air-cooled condenser. An air-cooled condenser relies upon forced convection from a fan to operate, thus a lower pressure drop results in less fan power and thus better operating efficiency.

Accordingly, there is a desire for an improved compact fin and tube heat exchanger to increase the heat transfer rate per unit pressure loss so as to provide a smaller and less expensive heat exchanger with lower energy losses and lower overall life cycle costs. Such a fin and tube heat exchanger preferably may be used for a variety of gas to liquid or gas to steam heat transfer applications and specifically may be used for air-cooled condensers utilized in power plant operations and the like.

BRIEF DESCRIPTION

The present application is directed to an embodiment of a fin and tube heat exchanger. The fin and tube heat exchanger may include a plurality of tubes; and a plurality of substantially spirally-wound circular fins positioned on each of the plurality of tubes. The plurality of tubes comprising a first set of tubes comprising a plurality of tube groupings and a second set of tubes comprising a plurality of tube groupings. The first set of tubes comprises a transverse offset position as compared to the second set of tubes.

Another embodiment of the present application is directed to a fin and tube heat exchanger including a plurality of tubes; and a plurality of substantially spirally-wound circular fins positioned on each of the plurality of tubes. The plurality of tubes comprising a first set of tubes comprising a first row of tubes and a second row of tubes, wherein a plurality of tube pairs are defined therein by a tube in the first row of tubes and an inline tube in the second row of tubes. The plurality of tubes further comprising a second set of tubes comprising a third row of tubes and a fourth row of tubes, wherein a plurality of tube pairs are defined therein by a tube in the third row of tubes and an inline tube in the fourth row of tubes. The first set of tubes comprises a transverse offset position as compared to the second set of tubes.

The present application further provides yet another embodiment of a fin and tube heat exchanger. The fin and tube heat exchanger may include a plurality of tubes; and a plurality of substantially spirally-wound circular fins positioned on each of the plurality of tubes. The plurality of tubes comprising a first set of tubes and a second set of tubes. The first set of tubes comprising a first row of tubes and a second row of tubes, wherein the first row of tubes and the second row of tubes comprise an inline position relative to a flow across the first row of tubes and the second row of tubes. A plurality of tube pairs are defined therein. Each of the plurality of tube pairs comprising a tube in the first row of tubes and a tube in the second row of tubes. The second set of tubes comprising a third row of tubes and a fourth row of tubes. The third row of tubes and the fourth row of tubes comprise an inline position relative to a flow across the third row of tubes and the fourth row of tubes. A plurality of tube pairs are defined therein. Each of the plurality of tube pairs comprising a tube in the third row of tubes and a tube in the fourth row of tubes. The first set of tubes comprises a transverse offset position as compared to the second set of tubes.

These and other features and improvements of the present application will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

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The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the subsequent detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of a gas turbine engine;

FIG. 2 is a schematic view of a system for use in a power plant including an air-cooled condenser;

FIG. 3 is a three-dimensional view of a portion of a semi-staggered fin and tube heat exchanger as may be described herein;

FIG. 4 is an end view of a portion of a semi-staggered fin and tube heat exchanger as may be described herein;

FIG. 5 is an end view of a portion of a semi-staggered fin and tube heat exchanger illustrating transverse fin and tube spacing as may be described herein;

FIG. 6 is an end view of a portion of a semi-staggered fin and tube heat exchanger illustrating longitudinal fin and tube spacing as may be described herein;

FIG. 7 is an end view of a portion of a semi-staggered fin and tube heat exchanger illustrating fin and tube spacing as may be described herein;

FIG. 8 is a perspective view of a portion of a semi-staggered fin and tube heat exchanger as may be described herein;

FIG. 9 is an end view of a portion of a semi-staggered fin and tube heat exchanger as may be described herein illustrating computational fluid dynamics and resultant streamlines; and

FIG. 10 is diagram of a portion of a semi-staggered fin and tube heat exchanger as may be described herein illustrating computational fluid dynamics and resultant streamlines and heat transfer coefficient.

DETAILED DESCRIPTION

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Referring now to the drawings, in which like numerals refer to like elements throughout the several views, FIG. 1 shows a schematic view of a gas turbine engine 100 as may be described herein. The gas turbine engine 100 may include a compressor 110. The compressor 110 compresses an incoming flow of air 120. The compressor 110 delivers the compressed flow of air 120 to a combustor 130. The combustor 130 mixes the compressed flow of air 120 with a compressed flow of fuel 140 and ignites the mixture to create a flow of combustion gases 150. Although only a single combustor 130 is shown, the gas turbine engine 100 may include a number of combustors 130.

The flow of combustion gases 150 is in turn delivered to a turbine 160. The flow of combustion gases 150 drives the turbine 160 so as to produce mechanical work via the turning of a turbine shaft 170. The mechanical work produced in the turbine 160 drives the compressor 110 and an external load such as an electrical generator 180 and the like via the turbine rotor 170.

The flow of now spent combustion gases 150 then may be delivered to a heat recovery steam generator 190 or other types of heat exchanger. The flow of the spent combustion gases 150 to the heat recovery steam generator 190 may heat a flow of feedwater and steam 200 therethrough for use in, for example, a steam turbine, process heating, fuel preheating, and/or for other types of work. The flow of the combustion gases 150 then may be vented through a stack or otherwise disposed.

The gas turbine engine 100 may use natural gas, various types of petroleum-based liquid fuels, synthesis gas, and other types of fuels. The gas turbine engine 100 may be any number of different turbines offered by General Electric Company of Schenectady, N.Y. or otherwise. The gas turbine engine 100 may have other configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines 100, other types of turbines, and other types of power generation equipment may be used herein together.

Generally described, the heat recovery steam generator 190 may be a non-contact heat exchanger that allows feedwater for the steam generation process and the like to be heated by the otherwise wasted flow of the spent combustion gases 150. The heat recovery steam generator 190 may be a large duct with tube bundles interposed therein such that water is heated to steam as the flow of combustion gases 150 pass through the duct. Other heat recovery steam generator configurations and other types of heat exchange devices may be used herein.

FIG. 2 shows a schematic view of a system 210 for use in a power plant, such as a combined cycle power plant as may be described herein. For combined cycle power plants to be used in water scarce regions of the world, an air-cooled condenser may be installed due to the unavailability of water. The power plant includes an energy source, such as a gas turbine 220, which generates heat 225 during operations thereof, a heat recovery steam generator (HRSG) 230, which is coupled to the gas turbine 220, a cooling tower 235 and steam turbines 240, such as a high pressure steam turbine (HPST) 245, an intermediate pressure steam turbine (IPST) 250 and a low pressure steam turbine (LPST) 255. The HRSG 230 generates steam by way of the heat generated by the gas turbine 220 and includes heat exchangers, such as super heaters, evaporators, and pre-heaters, which are disposed along an axis thereof, and by which portions of the generated steam are diverted to the HPST 245, the IPST 250, and the LPST 255. The HPST 245, the IPST 250 and the LPST 255 generate power, such as electricity, by way of the diverted steam, and output spent steam supplies. An air-cooled condenser 260 is configured to fluidly receive and to air-cool at least a steam supply 265. The air-cooled condenser 260 operates with electrically driven fans and cools the steam supply 265 via a supply of air 270. It is noted that the power plant shown in FIG. 2 is merely exemplary and that other configurations of the same are possible.

Referring now to FIGS. 3 and 4, illustrated is a portion of a semi-staggered fin and tube heat exchanger 300 as may be described herein. The semi-staggered fin and tube heat exchanger 300 may be used as part of the heat recovery steam generator 190 of FIG. 1, or as part of the air-cooled condenser 265 of FIG. 2, or for any type of heat exchange device or purpose.




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stats Patent Info
Application #
US 20120305227 A1
Publish Date
12/06/2012
Document #
File Date
12/31/1969
USPTO Class
Other USPTO Classes
International Class
/
Drawings
0




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20121206|20120305227|fin and tube heat exchanger|The present application provides a fin and tube heat exchanger. The fin and tube heat exchanger may include a number of tubes with a number of substantially spirally wound circular fins positioned on each of the tubes. The tubes may include a first set of tubes including a plurality of |General-Electric-Company
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