Patent Grant
8662150
The subject matter disclosed herein related generally to heat exchangers, and more particularly to media pads in heat exchangers.
Gas turbines are widely utilized in fields such as power generation. A conventional gas turbine system includes a compressor, which compresses ambient air; a combustor for mixing compressed air with fuel and combusting the mixture; and a turbine, which is driven by the combustion mixture to produce power and exhaust gas.
Various strategies are known in the art for increasing the amount of power that a gas turbine is able to produce. One way of increasing the power output of a gas turbine is by cooling the ambient air before compressing it in the compressor. Cooling causes the air to have a higher density, thereby creating a higher mass flow rate into the compressor. The higher mass flow rate of air into the compressor allows more air to be compressed, allowing the gas turbine to produce more power. Additionally, cooling the ambient air generally increases the efficiency of the gas turbine.
Various systems and methods are utilized to cool the ambient air entering a gas turbine. For example, heat exchangers may be utilized to cool the ambient air through latent cooling or through sensible cooling. Many such heat exchangers utilize a media pad to facilitate cooling of the ambient air. These media pads allow heat and/or mass transfer between the ambient air and a coolant. The ambient air interacts with the coolant in the media pad, cooling the ambient air.
Known media pads for use in heat exchangers are formed from, for example, cellulose fibers. Cellulose fiber-based media pads generally include a stiffening agent designed to maintain the structural integrity of the media pad when a coolant, such as water, is flowed through the media pad. However, cellulose fiber-based media pads are generally not suitable in situations requiring a high volume of coolant, which may dissolve the stiffening agent and collapse the media pad. Further, cellulose fiber-based media pads may be particularly sensitive to the quality of coolant flowed therethrough, and may therefore require the use of “fouled” coolant rather than clean coolant for the media pad to perform properly.
Other known media pads are formed from non-porous, solid plastic materials. These media pads are generally not able to evenly and fully distribute coolant throughout the surface area of the pads. This can inhibit efficient cooling of the ambient air and, in some cases, may result in dry spots that cause hot streaks of air, which can be detrimental to the operation of the gas turbine compressor. Additionally, at relatively higher air flow velocities, these media pads may be unable to retain the coolant, and may instead have a tendency to shed coolant.
Thus, a media pad that provides more efficient cooling and is not sensitive to coolant quality would be desired in the art. Additionally, a media pad that will maintain structural integrity when a high volume of coolant is flowed therethrough would be advantageous. Further, a media pad that reduces or prevents dry spots and resulting hot streaks would be desired. Finally, a media pad that retains coolant at relatively higher air flow velocities would be advantageous.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one embodiment, a media sheet for a heat exchanger is disclosed. The media sheet includes a first layer having a first outer surface and a second layer having a second outer surface. The first and second layers define a plurality of passages extending therebetween. At least one of the first and second outer surfaces comprises a plurality of depressions. The plurality of depressions further define the plurality of passages therebetween. The media sheet is polymer fiber-based and wettable.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
The system 10 may further include a gas turbine inlet 20. The inlet 20 may be configured to accept an inlet flow 22. For example, in one embodiment, the inlet 20 may be a gas turbine inlet house. Alternatively, the inlet 20 may be any portion of the system 10, such as any portion of the compressor 12 or any apparatus upstream of the compressor 12, which may accept the inlet flow 22. The inlet flow 22 may, in exemplary embodiments, be ambient air, which may be conditioned or unconditioned. Alternatively, the inlet flow 22 may be any suitable fluid, and may preferably be any suitable gas.
The system 10 may further include an exhaust outlet 24. The outlet 24 may be configured to discharge gas turbine exhaust flow 26. In some embodiments, the exhaust flow 26 may be directed to a heat recovery steam generator (not shown). Alternatively, the exhaust flow 26 may be, for example, directed to an absorption chiller (not shown) or dispersed into ambient air.
The system 10 may further include a heat exchanger 30. It should be understood that the heat exchanger 30 of the present disclosure is not limited to applications in systems 10. Rather, use of a heat exchanger 30 in any system requiring a heat exchange operation is within the scope and spirit of the present disclosure.
The heat exchanger 30 may be configured to cool the inlet flow 22 before the inlet flow 22 enters the compressor 12. For example, the heat exchanger 30 may be disposed in the gas turbine inlet 20, or may be upstream or downstream of the gas turbine inlet 20. The heat exchanger 30 may allow the inlet flow 22 and a heat exchange medium 32 to flow therethrough, and may facilitate the interaction of the inlet flow 22 and the heat exchange medium 32 to cool the inlet flow 22 before it enters the compressor 12. The heat exchange medium 32 may, in exemplary embodiments, be water. Alternatively, the heat exchange medium 32 may be any suitable fluid, and may preferably be any suitable liquid.
The heat exchanger 30 may, in exemplary embodiments, be a direct-contact heat exchanger 30. The heat exchanger 30 may include a heat exchange medium inlet 34, a heat exchange medium outlet 36, and a media pad 38. The inlet 34 may flow the heat exchange medium 32 to the media pad 38. For example, in one embodiment, the inlet 34 may be a nozzle or a plurality of nozzles. The outlet 36 may accept heat exchange medium 32 exhausted from the media pad 38. For example, in one embodiment, the outlet 36 may be a sump disposed downstream of the media pad 38 in the direction of flow of the heat exchange medium 32. In an exemplary embodiment, heat exchange medium 32 may be directed in a generally or approximately downward direction from inlet 34 through media pad 38, and inlet flow 22 may be directed through the heat exchanger 30 in a direction generally or approximately perpendicular to the direction of flow of the heat exchange medium 32.
In some embodiments, a filter 42 may be disposed upstream of the media pad 38 in the direction of inlet flow 22. The filter 42 may be configured to remove particulate from the inlet flow 22 prior to the inlet flow 22 entering the media pad 38, thus preventing the particulate from entering the system 10. Alternatively or additionally, a filter 42 may be disposed downstream of the media pad 38 in the direction of inlet flow 22. The filter 42 may be configured to remove particulate from the inlet flow 22 prior to the inlet flow 22 entering the system 10.
In some embodiments, a drift eliminator 44 may be disposed downstream of the media pad 38 in the direction of inlet flow 22. The drift eliminator 44 may act to remove droplets of heat exchange medium 32 from the inlet flow 22 prior to the inlet flow 22 entering the system 10.
The heat exchanger 30 may, in some embodiments, be configured to cool the inlet flow 22 through latent, or evaporative, cooling. Latent cooling refers to a method of cooling where heat is removed from a gas, such as air, resulting in a change in the moisture content of the gas. Latent cooling may involve the evaporation of a liquid at ambient temperature to cool the gas. Latent cooling may be utilized to cool a gas to near its wet bulb temperature.
In alternative embodiments, the heat exchanger 30 may be configured to chill the inlet flow 22 through sensible cooling. Sensible cooling refers to a method of cooling where heat is removed from a gas, such as air, resulting in a change in the dry bulb and wet bulb temperatures of the air. Sensible cooling may involve chilling a liquid, and then using the chilled liquid to cool the gas. Sensible cooling may be utilized to cool a gas to below its wet bulb temperature.
It should be understood that latent cooling and sensible cooling are not mutually exclusive cooling methods, and may be applied either exclusively or in combination. It should further be understood that the heat exchanger 30 of the present disclosure is not limited to latent cooling and sensible cooling methods, but may cool, or heat, the inlet flow 22 through any suitable cooling or heating method.
Referring now to
The media pad 38 may further include a plurality of spacers 54. The spacers 54 may at least partially define the inlet flow passages 52. For example, each of the spacers 54 may be associated with at least one media sheet 50, and in some embodiments a plurality of media sheets 50. In one embodiment as shown in
The media pad 38 may further include a plurality of mounts 58. In one embodiment, as shown in
The spacers 54 and mounts 58 may further allow the media sheets 50 to be adjustable within the heat exchanger, and relative to each other, if desired. For example, during operation of the system 10 during relatively hotter periods, such as during the summer or in the afternoon, the spacers 54 and mounts 58 may be utilized to position the media sheets 50, and thus the media pad 38, for optimal cooling or heating of the inlet flow 22. During relatively cooler periods, however, such as during the winter or in the evening, cooling or heating of the inlet flow 22 may not be required. In these situations, the spacers 54 may be removed and/or the mounts 58 utilized to adjust the media sheets 50 out of the flow path of the inlet flow 22. Thus, the media sheets 50 and media pad 38 may be adjustable as desired for optimal and efficient performance of the system 10.
The first and second layers 70, 74 may generally define the periphery 78 of the media sheet 50. The media sheet 50 may be, in exemplary embodiments, generally rectangular. Alternatively, however, the media sheet 50 may be, for example, circular or oval, triangular, or any other suitable polygonal shape.
The media sheet 50 may, in general, be a polymer fiber-based media sheet 50 and, as discussed below, may be wettable. For example, the media sheet 50 may be formed from polyacrylates, polyamides (such as, for example, nylon), polyesters, polycarbonates, polyimides, polystyrenes, polyethylenes, polyurethanes, polyvinyls, polyolefins, or any other suitable polymer fibers. Further, the media sheet 50 may be, for example, a woven product or a non-woven product, and may be formed using any suitable processes, including, for example, wet-laying, spin-laying, air-laying, spin-blowing, melt-blowing, weaving, knitting, and/or sewing. The media pad 38 may thus generally be utilized with any variety of heat exchange mediums 32, and may not be sensitive to the quality of the heat exchange medium 32. For example, in one exemplary embodiment, the heat exchange medium 32 may be pure water, and the pure water may not require any fouling. Of course, it should be understood that fouled water, or any other suitable pure or fouled fluid, may be utilized as the heat exchange medium 32. Further, the media pad 38 may thus generally maintain its structural integrity when provided with a high volume of heat exchange medium 38, rather than collapsing or dissolving.
It should further be understood that the media sheets 50 may be formed from copolymers, and may further be composite media sheets 50. For example, the media sheets 50 may include any suitable metals, such as, for example, steel, aluminum, brass, or other metals or metal alloys, or ceramics, such as, for example, glass or other suitable ceramics or ceramic composites. The metals and/or ceramics may be, for example, strands that are embedded in the polymer fiber-based media sheets 50 to provide beneficial heat exchange medium 32 distribution properties or strength properties.
The first and second layers 70, 74 may define a plurality of passages 80 extending therebetween. For example, the passages 80 may be defined by both the first and second layers 70, 74, as shown in
The passages 80 may extend in any variety of directions and patterns through the media sheet 50. For example, in one embodiment as shown in
It should be understood that the passages 80 may have any suitable patterns, and may be of any suitable size, for flowing heat exchange medium 32 therethrough. It should additionally be understood that the passages 80 may be tapered, or may have any other modifications or alterations, along the lengths of the passages 80. Further, it should be understood that the passages 80 may extend to the periphery 78 of the media sheet 50, or may extend only partially through the media sheet 50, not reaching the periphery 78. Finally, it should be understood that each passage 80 may vary from the other various passages 80, and that the passages 80 defined in a media sheet 50 need not be identical.
In exemplary embodiments, at least a portion of the plurality of passages 80 may each include an inlet opening 84. The inlet openings 84 may be configured to accept heat exchange medium 32. For example, at least a portion of the heat exchange medium 32 flowed to the media pad 38 from the inlet 34 may be directed to various of the inlet openings 84. The heat exchange medium 32 may be accepted by the inlet openings 84 to be flowed through the passages 80.
At least one of the first and second outer surfaces 72, 76, and in exemplary embodiments both the first and second outer surfaces 72, 76, may comprise a plurality of depressions 90. The depressions 90 may generally define the plurality of passages 80 therebetween. For example, in exemplary embodiments, the depressions 90 may be formed through bonding, molding, forming, or drawing, or otherwise attaching or producing, and the resulting portions of the media sheet 50 that do not form the depressions 90 may form the passages 80. Alternatively, the passages 80 may be formed by, for example, cutting the passages 80 into the media sheet 50 through the thickness of the media sheet. The remainder of the media sheet 50 not including the passages 80 may be considered to include depressions 90.
As mentioned, the depressions 90 may be formed through, for example, bonding, molding, forming, or drawing, or any other suitable process for attaching or producing the various layers of the media sheet 50, including the first layer 70 and second layer 74. For example, bonding may include thermal bonding, physical or mechanical bonding (such as through pressing), ultrasonic bonding, chemical bonding, or weaving, knitting, needling, or sewing, or bonding through the use of an adhesive. Forming may include, for example, cold forming, roll forming, vacuum forming, or thermoforming. Bonding, molding, forming, drawing or otherwise attaching or producing the various layers of the media sheet 50 to create depressions 90 may form passages 80 therebetween.
The plurality of depressions 90 fanned in the media sheet 50 may include an inlet depression 92 and an outlet depression 94. The inlet and outlet depressions 92, 94 may be depressions defined adjacent the periphery 78 of the media sheet 50. For example, the inlet depression 92 may be defined adjacent the periphery 78 at the upstream edge of the media sheet 50 with respect to the inlet flow 22, such as where the inlet flow 22 may first interact with the media sheet 50 and media pad 38. The outlet depression 94 may be defined adjacent the periphery 78 at the downstream edge of the media sheet 50 with respect to the inlet flow 22, such as where the inlet flow 22 may exit the media sheet 50 and media pad 38. The inlet and outlet depressions 92, 94 may reduce the pressure drop associated with the inlet flow 22 as the inlet flow travels through the media pad 38, and/or may be shaped to aid the heat transfer and mixing between the inlet flow 22 and the heat exchange medium 32, such as by creating a turbulent inlet flow 22. In one exemplary embodiment, the outlet channel 94 may be further configured to capture heat exchange medium 32 before the heat exchange medium 32 is exhausted from the media pad 38 with the inlet flow 22.
In exemplary embodiments, the media sheet 50 may be wettable. Thus, the media sheet 50 may be formed such that the heat exchange medium 32 may be able to maintain contact with the media sheet 50, and may further be able to spread throughout the media sheet 50. Further, the media sheet 50 may be hydrophilic and/or porous. Thus, the media sheet 50 may generally be able to accept, absorb, flow, and distribute heat exchange medium 32 throughout the surface area of the media sheet 50. For example, heat exchange medium 32 provided to the media sheet 50, such as provided by the inlets 34, may wet the media sheet 50 and flow through the media sheet 50. In exemplary embodiments, the heat exchange medium 32 may be distributed relatively evenly throughout the surface area of the media sheet 50, reducing or eliminating dry spots on the heat exchange medium 32. Further, heat exchange medium 32 flowed through the inlet openings 84 into the passages 80 may pass through the passages 80 and flow into and through the depressions 90, and heat exchange medium 32 flowed through the depressions 90 may pass from the depressions 90 into the passages 80.
The passages 80 may, in general, be raised portions of the media sheet 50 relative to the depressions 90. For example, the passages 80 may be raised portions of the first layer 70 and first outer surface 72, and/or may be raised portions of the second layer 74 and the second outer surface 76, relative to the depressions 90. Thus, the inlet flow passages 52 between media sheets 50 may be further defined by the depressions 90 and the raised passages 80. Thus, the inlet flow passages 52 may promote turbulent inlet flow 22 through the media pad 38, beneficially enhancing the heat exchange between the inlet flow 22 and the heat exchange medium 32. Further, as mentioned above, the inlet depressions 92 and outlet depressions 94 may reduce the pressure drop associated with the inlet flow 22 through the media pad 38.
Thus, the media pad 38 of the present disclosure may provide more efficient cooling or heating of inlet flow 22. Additionally, the media pad 38 may be utilized with any variety of heat exchange mediums 32, and may not be sensitive to the quality of the heat exchange medium 32. Finally, the media pad 38 of the present disclosure may maintain its structural integrity when provided with a high volume of heat exchange medium 38, and may beneficially absorb, flow, and distribute heat exchange medium 38 throughout the surface area of the media pad 38 and media sheets 50 therein, thus eliminating potentially dangerous dry spots and promoting the cooling or heating of inlet flow 22.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
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| Number | Date | Country | |
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