Title:
Heat Exchanger with Sloped Baffles
Kind Code:
A1


Abstract:
A condenser is made from a heat exchanger including a tube bundle within a shell. The tube bundle has an interior section within a periphery, and at least two sloped baffles are positioned in the tube bundle. Each sloped baffle has an inner edge which is within the tube bundle interior, and a gap is defined between the inner edges.



Inventors:
Luo, Zhong (Shanghai, CN)
Qiu, Yalin (Shanghai, CN)
Application Number:
12/194604
Publication Date:
02/26/2009
Filing Date:
08/20/2008
Assignee:
Wolverine Tube, Inc. (Huntsville, AL, US)
Primary Class:
Other Classes:
165/178
International Classes:
F25B1/00; F28F9/04
View Patent Images:
Related US Applications:



Primary Examiner:
COX, ALEXIS K
Attorney, Agent or Firm:
BRADLEY ARANT BOULT CUMMINGS LLP (HUNTSVILLE, AL, US)
Claims:
We claim:

1. A condenser comprising: A shell; A tube bundle positioned within the shell, the tube bundle having an interior; At least two sloped baffles positioned in the tube bundle, wherein the two sloped baffles include inner edges positioned in the tube bundle interior, and the inner edges define a gap.

2. The condenser of claim 1 wherein the condenser has a standard position, and wherein each tube within the tube bundle has a baffle either directly over or directly under the tube when the condenser is in the standard position.

3. The condenser of claim 2 wherein the tubes are positioned in tube rows, and there is a maximum of 10 tube rows directly above any one point on the baffle when the condenser is in the standard position.

4. The condenser of claim 1 wherein the tubes in the tube bundle are improved.

5. The condenser of claim 1 wherein the shell includes a shell inner space, the condenser further comprising two tube sheets dividing the shell inner space into a shell side chamber between tube side headers, the shell side chamber further including a vapor inlet and a condensate outlet and the tube side headers including a coolant inlet and a coolant outlet, and wherein each tube penetrates two tube sheets.

6. The condenser of claim 1 wherein the shell includes a shell wall and the baffles include an outer edge adjacent the shell wall.

7. The condenser of claim 1 wherein the gap extends for the entire length of the sloped baffle inner edge.

8. The condenser of claim 1 wherein the sloped baffles have a slope angle between about 3 degrees and about 30 degrees.

9. The condenser of claim 1 wherein the sloped baffles are selected from the group consisting of a smooth plate, a corrugated plate, a grooved plate, a multi-hole plate, a serrated plate, and any combination thereof.

10. A condenser comprising: A shell having a shell inner space; A tube bundle positioned in the shell inner space, where the tube bundle includes interior tubes; A first baffle positioned in the tube bundle, the first baffle being sloped such that the first baffle and a horizontal plane define a slope angle, the first baffle including a first inner edge positioned adjacent to at least one interior tube; and A second baffle positioned in the tube bundle, the second baffle being sloped such that the second baffle and the horizontal plane define a slope angle, the second baffle including a second inner edge positioned adjacent at least one interior tube, and wherein the first and second baffle do not touch each other.

11. The condenser of claim 10 wherein the condenser has a standard position, and wherein each tube within the tube bundle has a baffle either directly over or directly under the tube when the condenser is in the standard position.

12. The condenser of claim 11 wherein the tubes are positioned in tube rows, and there is a maximum of 10 tube rows directly above any one point on the baffle when the condenser is in the standard position.

13. The condenser of claim 10 wherein the tubes in the tube bundle are improved.

14. The condenser of claim 10 further comprising at least two tube sheets which divide the shell inner space into at least a shell side chamber between two tube side headers, wherein the shell side chamber includes a vapor inlet and a condensate outlet and the tube side headers include a coolant inlet and a coolant outlet, and the tube side headers are connected by the tube bundle.

15. The condenser of claim 10 wherein the shell has a shell wall, the first baffle has a first outer edge adjacent the shell wall, the second baffle has a second outer edge adjacent the shell wall, and the first and second inner edges of the first and second baffles define a gap.

16. The condenser of claim 15 wherein the condenser has a standard position and wherein the baffles slope upwards from the shell wall when the condenser is in the standard position.

17. The condenser of claim 10 wherein the slope angles are between about 3 degrees and about 30 degrees.

18. The condenser of claim 10 wherein the sloped baffles are selected from the group consisting of a smooth plate, a corrugated plate, a grooved plate, a multi-hole plate, a serrated plate, and any combination thereof.

19. A refrigeration system comprising: an evaporator; a compressor in fluid communication with the evaporator; a pressure valve in fluid communication with the evaporator; a condenser in fluid communication with the compressor and the pressure valve, where the condenser includes; a shell having a shell wall; a tube bundle within the shell, where the tube bundle includes interior tubes; and at least two sloped baffles within the shell, the sloped baffles having inner edges, where each inner edge is adjacent at least one interior tube, and wherein the sloped baffle inner edges define a gap.

20. The refrigeration system of claim 19 wherein the tubes in the tube bundle are improved.

21. The refrigeration system of claim 19 wherein the condenser is a double pass shell and tube heat exchanger.

Description:

This invention claims priority to Chinese Patent application number ZL200720073862.2, filed on Aug. 21, 2007, whose title has been translated as A HORIZONTAL CONDENSER WITH VERTICAL BUFFERS.

BACKGROUND OF THE INVENTION

a. Field of the Invention

This invention relates to shell and tube heat exchangers used as condensers to condense a vapor into a liquid.

b. Description of the Related Art

Condensers are used to condense a vapor into a liquid condensate. The vapor transfers heat to a coolant which is heated by the condensing vapor. Typically, a shell and tube heat exchanger is used as a condenser, where the vapor is directed around the outside of the tubes in the heat exchanger, and the coolant passes through the inside of the tubes. The condensate is collected at the bottom of the shell.

The vapor often enters the heat exchanger near the top of the tubes, and condenses on the tube outer surfaces. As the condensate condenses, it rains down on the lower tubes. As the condensate rains down on lower and lower tubes, a thicker and thicker layer of condensate develops on the tube outer surfaces, so the tubes near the bottom of the tube bundle have a thick condensate layer around them. The condensate layer acts as an insulator, so the efficiency of the tubes lower in the tube bundle is significantly decreased.

Different methods have been used to minimize the condensate collection on the tubes low in the tube bundle to increase the overall heat exchanger efficiency. Some techniques which have been used include providing heat exchangers which are not deep, so there are not very many rows of tubes. This minimizes the number of tubes over the lower tubes in the tube bundle. The tube outer surface can be modified to improve the ability of the tube to shed condensate, such as by forming fins, pins, or ridges on the tube outer surface.

The performance of a shell and tube heat exchanger can be enhanced by forcing the vapor on the outside of the tubes to travel a tortuous path through the tube bundle. This is most often done with a series of partial vertical baffles. In practice, the first baffle forces the vapor to pass over the top of the baffle near the top of the tube bundle, and the second baffle forces the vapor to pass under the bottom of the baffle near the bottom of the tube bundle. The third baffle then forces the vapor over the top of the baffle, and so on. This forces the vapor to traverse the heat exchanger from top to bottom while traversing the heat exchanger from side to side, and also increases the flow rate of the vapor past the tubes. The increased flow rate generally improves heat exchange efficiency, and the tortuous path also increases efficiency at by increasing the effective tube surface area transferring heat.

SUMMARY

A shell and tube heat exchanger is used as a condenser to condense vapor into a liquid. The condenser includes a plurality of tubes suspended between two tube sheets inside the shell. Coolant flows inside the tubes, and vapor and condensate flow outside the tubes, with heat being transferred through the tube wall. The plurality of tubes, or tube bundle, includes interior tubes inside of the tube bundle periphery. At least two sloped baffles are positioned within the tube bundle. The sloped baffles have an inner edge within the tube bundle, where the inner edge is adjacent to at least one interior tube. The sloped baffle also has an outer edge adjacent to a shell wall. Condensate rains down on the baffle, and then flows down the slope of the baffle.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 depicts a side cross sectional view of a single pass heat exchanger, with some of the tubes removed.

FIG. 2 depicts a side cross sectional view of a double pass heat exchanger.

FIG. 3 depicts an end cross sectional view of a heat exchanger with three sloped baffles.

FIG. 4 depicts a section of a one dimensional tube outer surface.

FIG. 5 depicts a section of a two dimensional tube outer surface.

FIG. 6 depicts a section of a three dimensional tube outer surface.

FIG. 7 depicts a refrigeration system.

FIG. 8 depicts an end cross sectional view of a heat exchanger with the slope angles shown.

FIG. 9 depicts an end cross sectional view of a heat exchanger with condensate and sloped baffles.

FIG. 10 depicts an end cross sectional view of a heat exchanger with condensate and no sloped baffles.

FIG. 11 depicts a flat plate.

FIG. 12 depicts a grooved plate.

FIG. 13 depicts a corrugated plate.

FIG. 14 depicts a serrated plate with a plurality of holes.

DETAILED DESCRIPTION

Heat Transfer Fundamentals

When heat is transferred from a condensing vapor on the outside of a tube to a cooling liquid on the inside of a tube, the heat transfer is considered in several distinct steps. The same basic steps apply when heat is transferred between any two mediums through a barrier, such as a tube wall. This description is directed towards a condensing vapor on the outside of the tube and a cooling liquid on the inside of the tube, but different applications are possible.

The vapor outside the tube transfers heat to a cooling liquid inside the tube. As a vapor condenses, a specific amount of heat is given off, and this quantity of heat is referred to as the heat of condensation. There is generally a layer of liquid condensate on the tube outer surface, so the first step is the transfer of heat from the vapor to the condensate on the tube. The heat then flows through the liquid condensate, and condensate often resists heat flow because it acts as an insulator. After heat flows through the condensate, it is transferred from the condensate to the tube outer surface. There is an interface between the condensate and the tube outer surface, and any interface provides some resistance to heat flow.

Once heat is transferred to the outer surface of the tube, it has to flow from the outer to the inner surface of the tube. To facilitate this heat flow, heat transfer tubes are usually made out of a material which readily conducts heat, or a heat conductor. Generally there is an essentially stagnant thin layer of liquid contacting the inner surface of the tube wall, and this layer next to the tube wall is essentially stagnant even if the fluid in the tube is moving. After the heat flows through the tube wall, it must be transferred from the inner surface of the tube wall to the adjacent layer of cooling liquid inside the tube. Heat then has to flow through this thin layer of liquid.

Often, a heat exchanger will use several rows of horizontal tubes, with the condensate from the upper rows raining down onto the lower rows. The tubes in the lower rows tend to become flooded, or covered in liquid condensate, which lowers the heat transfer efficiency. Because of this, the tubes near the top of the heat exchanger tend to operate at a higher efficiency than the tubes near the bottom of the heat exchanger. The thicker the layer of condensate on the tube, the greater the resistance to heat transfer.

Some things can be done to improve heat transfer in a heat exchanger. For example, increasing the surface area available for heat exchange generally improves heat transfer, and this can be done by making the heat exchanger larger. Designs which promote mixing or turbulent fluid flow around a heat transfer surface also tend to increase heat transfer.

Shell and Tube Heat Exchangers

Shell and tube heat exchangers are used for many heat transfer applications. A common embodiment of a shell and tube heat exchanger 10 uses a plurality of tubes 12 for heat transfer, as seen in FIGS. 1 and 2. The plurality of tubes 12 form a tube bundle 14, and the tube bundle 14 is positioned within a shell 16 of the heat exchanger 10. The shell 16 has an inner space 18, which is defined by a shell wall 20, and the shell 16 also has a shell outer surface 22.

In one embodiment, the shell inner space 18 is divided into three primary portions by two tube sheets 24. The tubes 12 run between the two tube sheets 24, and each tube 12 penetrates each tube sheet. The tube sheets 24 divide the shell inner space 18 into at least two tube side headers 26 and a shell side chamber 28. The shell side chamber 28 is between the tube side headers 26. The tube bundle 14 is positioned inside the shell side chamber 28, and fluid is able to flow from one tube side header 26 to another tube side header 26 through the tubes 12, so the tube bundle 14 connects the tube side headers 26.

The tube sheets 24 form a seal with each tube 12 and with the shell wall 20, so there is no liquid communication between the shell side chamber 28 and the tube side headers 26. Fluid flowing through the inside of the tubes 12 is referred to as the tube side fluid, and fluid flowing over the outside of the tubes 12 is referred to as shell side fluid.

A shell and tube heat exchanger 10 can be a single pass heat exchanger 10, as in FIG. 1, where the tube side fluid enters one tube side header 26 through a coolant inlet 21, flows through the tubes 12 to the other tube side header 26, and then exits the heat exchanger 10 through a coolant outlet 23. In a double pass heat exchanger 10, shown in FIG. 2, the tube side fluid enters a section of one tube side header 26, flows through a portion of the tubes 12 to the opposite tube side header 26, and then flows though a second portion of the tubes 12 back to a different section of the first tube side header 26. A divider 29 separates the sections of the tube side header 26. In this embodiment, the coolant inlet 21 and coolant outlet 23 are both on the same side of the heat exchanger 10. A heat exchanger 10 can also be a triple pass, quadruple pass, or more as desired.

In one embodiment, the tube side fluid is a coolant which is a liquid. Vapor to be condensed enters the shell side chamber 28 through a vapor inlet 25, which is on the top or side of the shell 16. The vapor enters the shell 16 as the shell side fluid, and the vapor condenses to a liquid condensate on the tube's outer surfaces 30. The heat exchanger 10 is positioned horizontally when in use, so the tubes 12 are horizontal in use, as opposed to being vertical or sloped. The designed position of the heat exchanger 10 when is use is referred to as the standard position in this description. The condensate condensing on tubes 12 near the top of the tube bundle 14 rains down on the lower tubes 12, which tends to insulate the lower tubes 12. The condensate flows out of the shell side chamber 28 of the heat exchanger 10 through the condensate outlet 27.

The tubes 12 in a heat exchanger 10 are positioned in some form or pattern, as seen in FIG. 3. In one embodiment, the pattern is organized, with the tubes 12 being arranged in a series of rows 32, where each row 32 is positioned above and/or below another row. The rows 32 start at one point on the shell wall 20, and proceed essentially horizontally across the heat exchanger 10 to another point on the shell wall 20. It is also possible for the rows 32 to angle up or down, so the rows 32 are not essentially horizontal. There can also be tube columns 34, but the tubes 12 can be positioned with tubes 12 from one row 32 being in between the tubes 12 from the row 32 directly above or below, which facilitates a tighter packing of tubes 12 in the tube bundle 14. In this case, a tube column 34 would run diagonally instead of vertically. Placing the tubes 12 closer together allows for more tubes 12, and therefore more area for heat transfer.

There can be support plates 36 to hold and stabilize the tubes 12, as seen in FIG. 2. In one embodiment, the support plates 36 are perforated, with the tubes 12 passing through the support plates 36. It is also possible for the support plates 36 to be a grid of wires or bars, or any other structure to support the tubes 12. The support plates 36 can reduce sagging of the tubes 12 between the tube sheets 24, and they can also reduce the bumping of tubes 12 against each other. There can be zero, one, two, or more support plates 36, as desired.

Referring now to FIGS. 4, 5, and 6, some heat exchangers 10 use improved tubes 12. The modification can be to the tube inner surface or the tube outer surface 30, and the surface can be one dimensional, two dimensional, or three dimensional. A flat tube outer surface 30, as shown in FIG. 4, is referred to as one dimensional in this description. If the tube outer surface 30 includes essentially parallel fins 40, as shown in FIG. 5, the outer surface 30 is said to be two dimensional in this description. FIG. 6 shows what this description refers to as a three dimensional outer surface 30, where essentially parallel fins 40 are further modified to include structure along the length of the fin 30, such as peaks, valleys, or slashes. The two and three dimensional tube surfaces 38 are defined as improved in this description. Improved tube surfaces 38 can be utilized in some embodiments to further improve heat transfer performance.

Slopped Baffles

The heat exchanger 10 includes at least two sloped baffles 54 within the tube bundle 14, as seen in FIG. 8, with further reference to FIGS. 2, 3, 9, and 10. The at least two sloped baffles 54 include at least a first baffle 55 and a second baffle 57. The condensate from the upper tubes 12 rains downward and lands on the sloped baffles 54 below. This condensate 56 then continues to flow down the slope of the sloped baffle 54 until it drops off an edge of the sloped baffle 54. In one embodiment, the condensate 56 drops off an outer edge 58 of the slopped baffle 54. Tubes 12 positioned directly below the sloped baffle 54 are protected from the condensate 56 raining down from the tubes 12 above the sloped baffle 54. The protected tubes 12 tend to be more efficient because of the decreased amount of condensate 56 accumulated on the tube outer surface 30.

The tube bundle 14 has an interior 60 with interior tubes 62. The tube bundle 14 also has a periphery 64 with exterior tubes 66. The exterior tubes 66 are those tubes 12 adjacent to the shell wall 20, and the interior tubes 62 are those tubes 12 within the exterior tubes 66. The outer edge 58 of the sloped baffle 54 is adjacent the shell wall 20, and so the outer edge 58 is adjacent or near the exterior tubes 66 and the tube bundle periphery 64. The sloped baffles 54 also have an inner edge 68 in the tube bundle interior 62, so the inner edge 68 is adjacent to at least one interior tube 62. A gap 70 is defined between the inner edges 68 of the at least two sloped baffles 54, so the gap 70 is within the tube bundle interior 60. The gap 70 can extend for the entire length of the inner edges 68, such that the inner edges 68 of different sloped baffles 54 do not touch. In one embodiment, the first and second sloped baffles 55, 57, and any other sloped baffles 54, so not touch each other at any point.

When the sloped baffles 54 are considered as at least the first and second sloped baffles 55, 57, the first baffle 55 includes a first inner edge 67 and a first outer edge 59 and the second baffle 57 includes a second inner edge 69 and a second outer edge 61. The gap 70 is then defined between the first inner edge 67 and the second inner edge 69. If there were more sloped baffles 54, there could be additional gaps 70 defined between the associated inner edges 68 within the tube bundle 14.

The sloped baffles 54 divide the tube bundle 14 into at least a top area 72 and a bottom area 74, where the top area 72 is above the sloped baffle 54 and the bottom area 74 is below the sloped baffle 54. If there are two or more sloped baffles 54 positioned above and below each other, the tube bundle can be divided into a top 72, a bottom 74 and one or more intermediate 76 areas. The sloped baffles 54 can direct the condensate 56 from an area above the sloped baffle 54 to the shell wall 20, so the area below the sloped baffle 54 is protected from the condensate 56 from the area above the sloped baffle 54. The bottom area 74 is protected from the condensate 56 of the top area 72 by the sloped baffle 54.

In one embodiment, the sloped baffles 54 are positioned so there are no more than ten tube rows 32 directly above any one point on the sloped baffle 54 when the condenser 44 is in the standard position. There may be more than ten rows 32 over the entire area of the sloped baffle 54, but no more than ten rows 32 above any single point on the sloped baffle 54. Limiting the number of rows 32 above a single point on the sloped baffle 54 limits the amount of condensate 56 which can rain down on the tubes 12 adjacent the top surface of the sloped baffle 54. Only the tubes 12 directly above the sloped baffle 54 can rain down condensate 56 on the tubes 12 adjacent the top surface of the sloped baffle 54.

Positioning the sloped baffles 54 to cover the entire width of the heat exchanger 10 results in every tube 12 having a sloped baffle 54 either directly above or directly below the tube 12, at least for a portion of the tube 12. This is done by extending the sloped baffle outer edges 58 to opposite sides of the heat exchanger 10, and by positioning the sloped baffle inner edges 68 to at least reach to the same vertical plane within the heat exchanger 10. In this description, a tube 12 is considered directly above or directly below a sloped baffle 54 if a vertical line extending from the tube 12 would contact a sloped baffle 54, regardless of any other tubes 12 in between.

The sloped baffles 54 have a slope angle 78 which is defined by the sloped baffle 54 and a horizontal plane 80 of the heat exchanger 10 when the heat exchanger 10 is in the standard position. The horizontal plane 80 is perpendicular to a vertical plane 81. The slope angle 78 can be different for each of the sloped baffles 54, or it can be the same. In one embodiment, the slope angle 78 directs the condensate 56 towards the shell wall 20, so the sloped baffles 54 angle upwards from the shell wall 20.

In one embodiment, the slope angle 78 is between about 3 degrees and about 30 degrees. A larger slope angle 78 results in the condensate 56 running off the sloped baffle 54 faster, and a smaller slope angle 78 slows the rate at which condensate 56 runs off the sloped baffle 54. The sloped baffles 54 take up area within the tube bundle 14, so the total number of tubes 12 which can be positioned in the tube bundle 14 is reduced by the presence of the sloped baffles 54. Increasing the slope angle 78 can result in a larger reduction in the total possible number of tubes 12 in the tube bundle 14. Also, if the condensate 56 runs off the sloped baffle 54 too quickly, it can splash up on tubes 12 near the sloped baffle outer edge 58.

Fluids are deflected by the sloped baffles 54. If the sloped baffles 54 are solid, fluids have to flow around the sloped baffles 54. Fluids can either pass between the sloped baffles 54 and the shell wall 20, or fluids can pass through the gap 70 defined by the baffle inner edges 68, or fluids can flow in front of or behind the sloped baffles 54 if the sloped baffles 54 do not extend the entire distance between the tube sheets 24. Both gases and liquids are fluids, and the sloped baffles 54 affect the flow of both.

Forcing the gases to follow a more tortuous path through the tube bundle 14 can increase the overall efficiency of the heat exchanger 10. If the gases have to follow a more tortuous path, the distance traveled by a set volume of gas is larger so the flow rate of the gases is increased. Increased flow rate tends to increase turbulence, which reduces the stagnant layer of fluid next to the tube 12 and increases heat transfer efficiency. However, deflecting the flow rate of gases through the heat exchanger 10 too much can negatively impact performance because the amount of liquids which can flow through the heat exchanger can be limited.

The size and positioning of the gap 70 between the sloped baffle inner edges 68 allows for a way to influence the amount of flow disturbance through the tube bundle 14. The condensate 56 flows over the sloped baffle outer edges 58, so liquid condensate 56 tends to at least partially block the space between the sloped baffles 54 and the shell wall 20. In one embodiment, the sloped baffles 54 do not direct condensate 56 towards the gap 70 between the inner edges 68.

Increased gas flow through the gap 70 also tends to strip condensate 56 off the tubes 12 in the gap 70. A rapid flow rate can blow the liquid condensate off of the tubes 12, which tends to expose the tube outer surface 30 for heat transfer. The tortuous path of the fluid through the gap 70 and around the tubes 12 serves to increase the overall efficiency of the condenser 44. Gases can also flow between the sloped baffle outer edges 58 and the shell wall 20, which further increases the curvature of the path of some of the gas, making an even more tortuous path.

A divider 29 in the tube side header 26 is used in double pass heat exchangers 10, and tubes 12 cannot be placed in the tube sheet 24 where the divider 29 contacts the tube sheet 24, as shown in FIG. 2. The divider 29 therefore produces a space or interruption in the tube bundle 14, and this space or interruption can be utilized for a sloped baffle 54. The sloped baffle 54 also requires the elimination of some tubes 12 from the tube bundle 14, so placing the sloped baffle 54 in the interruption from the divider 29 allows for a reduction in the total number of tubes 12 which are removed from the tube bundle 14 for the sloped baffles 54.

Types of Baffle Plates

The sloped baffles 54 can be constructed as a type of plate, where the plate is essentially a piece of material, such as metal or plastic, having a length and a width substantially larger than the depth. The plate can be flat, but it can also be bowed or curved. The plate can also have a wide variety of surface textures and shapes. For example, the plate can be smooth, as in FIG. 11, or grooved as in FIG. 12. The plate can be corrugated, as in FIG. 13, or it can be serrated as in FIG. 14. The plate can also include multiple holes, as in FIG. 14, with further reference to FIGS. 9, 11, 12, and 13. The use of groves 82, corrugations 84, serrations 86, holes 88, or other shapes can effect the flow of condensate 56 down the sloped baffle 54, which provides more options to heat exchanger designers.

Certain plates can provide additional strength, such as corrugations 84, and serrations 86 can direct the condensate 56 to drop from the plate at designated points. Grooves 82 can also direct the condensate 56 to flow and drop from the plate at designated points, which can facilitate vapor flow between the shell wall 20 and the sloped baffle outer edges 58. Holes 88 can allow vapor flow through the sloped baffle 54, which can be used to reduce flow resistance and/or to increase control over the vapor path through the heat exchange 10. It is also possible to combine any of these textures and shapes, so the plate could have multiple holes 88 and also corrugations 84, where the holes 88 are positioned on the elevated corrugations 84 of the plate.

The sloped baffles 54 can extend the entire length of the shell side chamber 28, so the sloped baffle would run from one tube sheet 24 to the opposite tube sheet 24, as best seen in FIG. 2 with further reference to FIG. 9. However, the sloped baffle 54 could run from one tube sheet 24 to a support plate 36, or the sloped baffle 54 could run from one support plate 36 to another support plate 36. Each of the different sloped baffles 54 could extend different portions of the shell side chamber 28, so one sloped baffle 54 could run from one tube sheet 24 to a support plate 36, and another sloped baffle 54 could run from the other tube sheet 24 to a different support plate 36.

There can be more than two sloped baffles 54, and each can run the same portion of the length of the shell side chamber 28, or each can run different portions, or any combination. One or more of the sloped baffles 54 can run the entire length of the shell side chamber 28 as well. The various possible placements still provide for a more tortuous path for the fluids through the tube bundle 14 than without the sloped baffles 54, and the sloped baffles 54 still direct condensate away from tubes 12 below the sloped baffles 54.

The sloped baffles 54 can include upward sloped flange structures where the sloped baffles 54 contact the support plate 36 or the tube sheet 24, and these upward sloped flange structures can help prevent leaks between the sloped baffle 54 and the support plate 36 or tube sheet 24.

Refrigeration

When a heat exchanger 10 is used for air conditioning or for refrigeration, one embodiment includes the use of water as the coolant fluid flowing inside the tubes 12, and some type of chloro fluoro carbon (CFC) or hydrogen chloro fluoro carbon (HCFC) as the shell side fluid which is being condensed. An embodiment of a refrigeration system 42 is shown in FIG. 7, where the term refrigeration, in this description, refers to a system for providing chilled or cooled fluid, such as an air conditioner, a freezer, or a system for maintaining food or other articles at reduced temperatures.

The refrigeration system 42 includes a condenser 44, where the refrigerant 45 is condensed from a vapor into a liquid. The condenser 44 is a type of heat exchanger 10. The refrigerant 45 can be a CFC or HCFC, but it can also be ammonia, methane, or other compounds. The condensed refrigerant 45 passes through a pressure valve 46, where the pressure on the refrigerant 45 is reduced. The reduced pressure refrigerant 45 then flows to an evaporator 48, where the refrigerant 45 is evaporated. The refrigerant 45 adsorbs heat as it evaporates, and this heat is transferred to the refrigerant 45 from a chilled fluid 50 in the evaporator 48. The temperature of the chilled fluid 50 is lowered in the evaporator 48. The chilled fluid 50 is then used for refrigeration purposes as desired. The evaporated refrigerant 45 is then pressurized in a compressor 52, and fed as a compressed gas into the condenser 44. The refrigerant 45 flows from the condenser 44 to the pressure valve 46, and then to the evaporator 48, and then to the compressor 52, so these components are all in fluid communication with each other.

Improvements in the efficiency of the condenser 44, as well as the evaporator 48, compressor 52, or other components, helps to improve the overall efficiency of the refrigeration system 42. Improved efficiency of the refrigeration system 42 lowers the amount of energy required for operation, which leads to cost savings.

EXAMPLE DIMENSIONS

Referring to FIGS. 1 through 10, an embodiment of the invention was produced and used with a 1758 kilowatt refrigeration unit, using R134a as the refrigerant 45. Water was used as the cooling liquid in the condenser 44, and the condensation side heat transfer performance was raised 12% to 55% over exiting technology. There were two support plates 36 in the middle of the tube bundle 14, and each of the two sloped baffles 54 ran from the same tube sheet 24 to the same support plate 36. The sloped baffles 54 were 2 mm thick, and there were a total of 27 tube rows 32. The inside diameter of the shell 16 was 700 millimeters (mm), and the length of the shell side chamber 28, which is from one tube sheet 24 to the other tube sheet 24, was 3,600 mm. The slope angle 78 was 5 degrees, the distance from the sloped baffle outer edges 58 to the shell wall 20 was 10 mm, and the gap 70 between the two sloped baffle inner edges 68 was 120 mm. The condenser 44 was a double pass heat exchanger.

Some typical dimensions which can be used include a 3 to 5 mm distance between adjacent tubes 12. The sloped baffles 54 can occupy the space of one to two tube rows 32 between the inner edge 68 and the outer edge 58.

Generally, as the tube bundle 14 becomes larger, more sloped baffles 54 can be used. Heat exchanger performance tends to increase more as larger tube bundles 14 with more sloped baffles 54 are used. Different types of tubes 12, such as one dimensional, two dimensional, or various forms of three dimensional outer tube surfaces 30, have different sensitivity to increased numbers of tube rows 32. The type of tube 12 used will influence the effect of sloped baffles 54, and design of condensers 44 should consider the type of tube 12 used.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed here. Accordingly, the scope of the invention should be limited only by the attached claims.





 
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