FLOW MODERATOR

Abstract

A fluid flow moderator for a plate heat exchange device comprises an open-sided fluid conduit adapted for positioning adjacent to a fluid port of a plate heat exchange device wherein said fluid conduit has a fluid deflection surface for moderating fluid flow. A method of moderating fluid flow in a plate heat exchange device comprises positioning an open-sided fluid conduit adjacent to a fluid port of a plate heat exchange device wherein said fluid conduit has a surface for deflecting a fluid and moderating fluid flow in said heat exchange device.

Description

FIELD OF THE INVENTION

This invention generally relates to heat exchange devices for fluids. In particular, the invention relates to a fluid flow moderator for a plate heat exchange device, a plate heat exchange device containing the fluid flow moderator and to a method of moderating fluid flow.

BACKGROUND OF THE INVENTION

Generally, plate heat exchange devices for fluids are assembled from a series of metallic plates packed vertically in sequence to form a series of fluid chambers.

The fluid chambers in a plate heat exchange device may alternately contain two fluids between which heat is to be exchanged.

Normally, fluid ports may be positioned adjacent the corners of the plates to form a manifold through the device which allows the flow (eg, by mechanical pumping) of fluid through and between the alternating fluid chambers. In this manner, each plate provides a heat exchange interface between the two fluids. This facilitates heat transfer between the fluids as they flow through the device cooling the higher temperature fluid while simultaneously heating the lower temperature fluid.

In certain circumstances, when fluid flows through the chambers, because of frictional effects localised areas of fluid turbulence can form due to irregularly-shaped features (eg, channels, indentations) present on the internal surface of the chambers and around the fluid ports. Energy is dissipated from the areas of fluid turbulence (also referred to as an eddy), which causes fluid pressure loss in the heat exchange device and hinders fluid flow. This can have a detrimental effect on heat transfer efficiency in the device.

Furthermore, in conventional plate heat exchange devices, the distribution of fluid over the surfaces of the heat-conducting plates can be uneven resulting in the fluid not always obtaining optimum exposure to the surface of the plate in order to facilitate efficient heat transfer. Again, this can have a detrimental effect on the overall heat transfer efficiency of the device.

Accordingly, a means for ameliorating these problems has been sought.

SUMMARY

According to the invention there is provided a fluid flow moderator for a plate heat exchange device comprising an open-sided fluid conduit adapted for positioning adjacent to a fluid port of a plate heat exchange device wherein said fluid conduit has a fluid deflection surface for moderating fluid flow.

It has surprisingly been found that the fluid flow moderator of the invention reduces localised areas of fluid turbulence in a plate heat exchange device and also provides a means for obtaining improved evenness of fluid distribution over the plates compared to conventional plate heat exchange devices.

This surprising effect is achieved by positioning the fluid flow moderator of the invention adjacent a fluid port of a fluid chamber in a plate heat exchange device so that fluid flows through the fluid conduit and is deflected by the inner surface of the conduit as it enters the chamber. In this manner, localised areas of fluid turbulence caused by frictional effects are minimised resulting in a reduced loss in fluid pressure. This also has the effect of more evenly distributing the fluid across the surface of a heat-conducting plate when the fluid is deflected because it is forced to flow in a radial direction from the open-sided portion of the conduit. Also, due to the even fluid flow distribution across the surface of the heat-conducting plate, improved heat exchange is observed.

Further according to the invention there is provided a plate heat exchange device comprising a fluid flow moderator, wherein said fluid flow moderator comprises an open-sided fluid conduit positioned adjacent to a fluid port of the plate heat exchange device wherein said fluid conduit has a fluid deflection surface for moderating fluid flow.

Even further according to the invention there is provided a method of moderating fluid flow in a plate heat exchange device, the method comprising positioning an open-sided fluid conduit adjacent to a fluid port of a plate heat exchange device wherein said fluid conduit has a surface for deflecting a fluid and moderating fluid flow in said heat exchange device.

According to some aspects of the invention, the fluid conduit may be a partial cylinder. In particular, the fluid conduit may be an open-ended and hollow partial cylinder. This provides a fluid conduit with an internal deflection surface which is arcuate, which assists deflection of the fluid in a controlled radial direction through a fluid port and into the fluid chamber through the open-ended portion of the cylinder. For clarification, it should be understood that arcuate means shapes which may correspond to partial circles or partial ellipses. U- or V-shaped internal surfaces for the fluid conduit may also be considered to be within the scope of the invention.

In some aspects of the invention, the open-sided portion of the fluid conduit can be an opening with parallel edges (eg, a longitudinal opening), which assists in the even distribution of the fluid in a fluid chamber by complementing the radial deflection of fluid from an arcuate deflection surface.

In some aspects of the invention, the open-sided fluid conduit may include a conduit which has a side wall which is only partially open. To exemplify, this may be a fluid conduit which is an open-ended hollow cylinder with one or more holes and/or slits present in its side wall. These holes and/or slits may be provided at locations in the wall which direct fluid flow in a desired direction. The term open-sided fluid conduit is intended to include all of the above-described constructions and any equivalents providing the same function.

The fluid conduit may be formed of a metallic material. However, in certain circumstances the fluid conduit may be formed of a plastics or other synthetic material for use in conditions where for example corrosive fluids are being cooled or heated. In any case, the skilled person will be able to select the material and dimensions for the fluid conduit dependent upon the environment in which it will be used.

According to some aspects of the invention, the fluid conduit may have a sealing ring to provide a seal between the fluid conduit and the fluid port. This can help to ensure that substantially all of the fluid flowing through a fluid port flows through the fluid conduit so that fluid flow remains controlled, homogeneous and without fluid turbulence. This is because fluid flowing between an external surface of a fluid conduit and a rim of a fluid port may create conditions of fluid turbulence.

The sealing ring may be welded on to the fluid conduit or otherwise connected to the fluid conduit by any other suitable means known to the person skilled in the art. The sealing ring may be constructed from a resilient temperature- and/or corrosion-resistant rubber material or a metallic material.

In some aspects of the invention, the fluid conduit may also be provided with a handle which provides a convenient means for removing the fluid flow moderator from a heat exchange device. The handle may be integral with the sealing ring or be attached to the fluid conduit separately.

According to some aspects of the invention, the fluid deflection surface is provided with indentations, corrugations and/or holes. These features can be arranged in a manner which assists in optimising flow distribution over the heat-exchange plates.

According to some aspects of the invention, an arcuate fluid deflection surface may be provided which subtends an angle of less than 360°, less than or equal to 270°, less than or equal to 180°, or less than or equal to 90°. Depending on the angle subtended by the arcuate deflection surface, fluid flow distribution over a heat-exchange plate can be modified to suit the requirements of the heat exchange device.

According to some aspects of the invention, a plate heat exchange device may be provided with a fluid flow moderator positioned adjacent a fluid port to moderate fluid flow as a fluid enters and/or exits a fluid port of a heat exchange plate in the heat exchange device.

According to some aspects of the invention, the plate heat exchange device may be provided with a series of heat exchange plates with fluid ports assembled to form a manifold defining flow passages for fluid flow through the heat exchange device.

The fluid used in accordance with the present invention may be a liquid or a gas. Furthermore, the fluid flow moderator, heat exchange device and method of moderating fluid flow in accordance with the invention are equally applicable both to processes in which a high-temperature fluid is cooled and to processes in which a low temperature fluid is heated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a conventional plate heat exchange device;

FIG. 2 shows a partial schematic view of heat exchange plates packed inside the plate heat exchange device of FIG. 1 forming fluid chambers and a counterflow arrangement of fluids through the chambers;

FIG. 3 shows partial diagrammatic representations of a conventional plate heat exchange device without a fluid flow moderator according to the invention (FIG. 3A) and a plate heat exchange device with a fluid flow moderator according to the invention (FIG. 3B);

FIG. 4 shows a plan view of a first embodiment of the fluid flow moderator of the invention;

FIG. 5 shows cross-sectional views of second (FIG. 5A), third (FIG. 5B) and fourth (FIG. 5C) embodiments of the fluid flow moderator according to the invention;

FIG. 6 shows plan views of fluid distribution over the surface of a heat exchange plate in a heat exchange device according to the invention having the fluid flow moderators of FIGS. 5A (FIG. 6A), 5B (FIG. 6B) and 5C (FIG. 6C), respectively, fitted; and

FIG. 7 shows a cross-sectional view of a fluid flow moderator according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, there is shown a plate heat exchange device 1 for heat exchange between two fluids flowing through the device whereby the higher temperature fluid is cooled and the lower temperature fluid is heated. The device 1 has a head support 5, an end support 10, a top carrying bar 15 and a bottom carrying bar 20.

Heat exchange plates (not shown) are vertically packed between head support 5 and end support 10 and secured by tie bars 21 on opposing sides of plate heat exchange device 1 to define a series of narrow fluid chambers (not shown) through which the two fluids can flow.

In this embodiment, fluid inlet ports 25,26 and fluid outlet ports 30,31 located on head support 5 provide a counterflow arrangement where one fluid flows between fluid inlet port 25 and fluid outlet port 30, and the other fluid flows between fluid inlet port 26 and fluid outlet port 31. As an alternative, the fluids may not be in a counterflow arrangement and can flow in the same direction through the fluid chambers 40.

Referring to FIG. 2, there are heat exchange plates 35 arranged in a sequence internally within the plate heat exchange device of FIG. 1 (not shown) to define a series of fluid chambers 40. Heat exchange plates 35 provide a heat exchange interface between fluid chambers 40 and have fluid ports 45 for the flow of a fluid between the fluid chambers 40.

The fluid chambers 40 alternately provide a fluid flow passage for a first fluid 50 (fluid chambers 40a) and a second fluid 55 (fluid chambers 40b). The fluid flow direction of fluids 50 and 55 through fluid chambers 40 is shown by arrows 60 and 65, respectively.

Fluid 50 enters heat exchange device 1 at fluid inlet port 25 near the top of heat exchange device 1 and exits at fluid outlet port 30 near the bottom of heat exchange device 1. Fluid 55 enters heat exchange device 1 at fluid inlet port 26 near the bottom of heat exchange device 1 and exits at fluid outlet port 31 near the top of heat exchange device 1. This provides a fluid counterflow arrangement of the two fluids 50,55 in heat exchange device 1.

In use, when fluid 50,55 contact opposing surfaces 70 of heat exchange plates 35, heat is exchanged across the plates 35 between the fluids 50,55 such that the higher temperature fluid is cooled and the lower temperature fluid is heated.

FIG. 3A shows heat exchange plates 35 of heat exchange device 1 separated by gaskets 75 and fluid 55 flowing through ports 45 in the direction of arrow 65. Channels 76 are present adjacent gaskets 75 resulting in localised turbulence of fluid 55 as shown by curved arrows 80. Arrows 85 show the direction of the flow of fluid 55 through fluid chambers 40b. For clarification, the independent fluid flow system of fluid chambers 40a containing cooling fluid 50 is also shown.

Referring to FIG. 4, there is shown a fluid flow moderator 90 which has a partially cylindrical fluid conduit 95 with an arcuate internal deflection surface 100 and a longitudinal opening 110 defined by edges 115. Deflection surface 100 has indentations 105.

FIG. 3B shows fluid flow moderator 90 positioned adjacent ports 45. In use, fluid 55 is blocked from migrating into channels 76 by deflection surface 100, thereby reducing fluid turbulence and improving the flow efficiency of fluid 55 through plate heat exchange device 1. Reduced loss of fluid pressure occurs and heat exchange from fluid 55 in fluid chambers 40b to fluid 50 in fluid chambers 40a is improved.

Referring to FIGS. 5A to 5C, there are shown further embodiments of fluid flow moderators 90. Fluid flow moderator 90 of FIG. 5A has a fluid conduit 96 with an arcuate deflection surface 101 subtending an angle of less than 180°. Fluid flow moderator 90 of FIG. 5B has a fluid conduit 97 with an arcuate deflection surface 102 subtending an angle of between 180° and 270°. Fluid flow moderator 90 of FIG. 5C has a fluid conduit 98 with an arcuate deflection surface 103 subtending an angle of between 180° and 270° and also has perforations 120. The different angles and surface features of the arcuate deflection surface 101,102,103 provide fluid flow moderators 90 with different deflection properties to suit individual fluid flow distribution requirements. This provides versatility and adaptability to the present invention.

Referring to each of FIGS. 6A to 6C, there is shown a heat exchange plate 35 with fluid ports 45 and fluid flow moderators 90.

Referring now to FIG. 6A, to optimise heat exchange across heat exchange plate 35, fluid flow should be distributed over heat exchange plate 35 in the directions A and B shown by arrows 125 and 130, respectively. In the absence of fluid flow moderator 90, flow is predominantly in direction A (ie, arrow 125), because this flow direction provides the least overall resistance between the vertically oriented fluid ports 45. This results in an uneven distribution of fluid over heat exchange plate 40 resulting in inefficient heat exchange. By using fluid flow moderator 90, fluid (not shown) entering a fluid chamber (not shown) through port 45 is deflected by the arcuate deflection surface 101 evenly in the directions A and B.

Likewise, as shown in FIGS. 6B and 6C, by using fluid flow moderator 90, fluid (not shown) entering a fluid chamber (not shown) through a port 45 is deflected by the arcuate deflection surfaces 102 and 103 in a radial pattern over a wide area of heat exchange plate 40 in the direction of arrows 105. Thus, the fluid is evenly distributed as it flows over heat exchange plate 35 providing an optimal level of contact with heat exchange plate 35 and efficient heat exchange.

With reference to FIG. 7, there is shown a fluid flow moderator 90 with fluid conduit 95 having fluid deflection surface 100 positioned adjacent fluid ports 45 with sealing rings 140 attached to the ends 101 of fluid conduit 95. Sealing ring 140 provides a seal between fluid conduit 95 and fluid port 45 so that substantially all of the fluid (not shown) is directed through fluid flow moderator 90. The sealing rings 110 are made from a temperature- and chemical resistant rubber and provide a tight seal of fluid conduit 90 with ports 45 (not shown). Alternatively, sealing ring 140 is made of a metallic material and is welded to fluid conduit 95.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

1. A fluid flow moderator for a plate heat exchange device comprising an open-sided fluid conduit adapted for positioning adjacent to a fluid port of a plate heat exchange device wherein said fluid conduit has a fluid deflection surface for moderating fluid flow

2. The fluid flow moderator according to claim 1, wherein said fluid conduit is a partial cylinder.

3. The fluid flow moderator according to claim 1, wherein said fluid conduit has an arcuate fluid deflection surface.

4. The fluid flow moderator according to claim 2, wherein said open-sided portion of said fluid conduit is a longitudinal opening.

5. The fluid flow moderator according to claim 1, further comprising a sealing ring for said fluid conduit.

6. The fluid flow moderator according to claim 5, wherein said fluid conduit further comprises a handle for removing said moderator from said heat exchange device.

7. The fluid flow moderator according to claim 1, wherein said fluid deflection surface has indentations, corrugations and/or holes.

8. The fluid flow moderator according to claim 3, wherein said arcuate fluid deflection surface subtends an angle of less than or equal to 270°.

9. The fluid flow moderator according to claim 1, wherein the fluid flow moderation is a reduction of pressure loss in and/or adjacent to the fluid port.

10. A plate heat exchange device comprising a fluid flow moderator, wherein said fluid flow moderator comprises an open-sided fluid conduit positioned adjacent to a fluid port of the plate heat exchange device wherein said fluid conduit has a fluid deflection surface for moderating fluid flow.

11. A plate heat exchange device according to claim 10, comprising a series of heat exchange plates with fluid ports assembled to form a manifold defining flow passages for fluid flow through said heat exchange device.

12. The plate heat exchange device according to claim 10, wherein said fluid conduit is a partial cylinder.

13. The plate heat exchange device according to claim 10, wherein said fluid conduit has an arcuate fluid deflection surface.

14. The plate heat exchange device according to claim 10, wherein said fluid deflection surface has indentations, corrugations and/or holes.

15. The plate heat exchange device according to claim 13, wherein said arcuate fluid deflection surface subtends an angle of less than or equal to 270°.

16. The fluid flow moderator according to claim 10, wherein the fluid flow moderation is a reduction of pressure loss in and/or adjacent to the fluid port.

17. A method of moderating fluid flow in a plate heat exchange device, the method comprising positioning an open-sided fluid conduit adjacent to a fluid port of a plate heat exchange device wherein said fluid conduit has a surface for deflecting a fluid and moderating fluid flow in said heat exchange device.

18. The method according to claim 17, wherein said fluid conduit is a partial cylinder.

19. The method according to claim 17, wherein said fluid conduit has an arcuate fluid deflection surface.

20. The method according to claim 19, wherein said arcuate fluid deflection surface subtends an angle of less than 270°.