US20140165641A1

US20140165641A1 - Distributor for evaporative condenser header or cooler header

Info

Publication number: US20140165641A1
Application number: US13/718,563
Authority: US
Inventors: Zahid Ayub; Peng Peng
Original assignee: American Sino Heat Transfer LLC
Current assignee: American Sino Heat Transfer LLC; AMSI HEAT TRANSFER LLC
Priority date: 2012-12-18
Filing date: 2012-12-18
Publication date: 2014-06-19

Abstract

A heat exchanger has heat exchange elements and an inlet header and an outlet header that fluidly communicate with the heat exchange elements. The inlet header has a fluid inlet. The heat exchange elements are connected to the inlet header along a length of the inlet header and are various distances from the fluid inlet. A distributor is located inside the inlet header, which distributor forms a perforated wall between the fluid inlet and the heat exchange elements. The distributor provides back pressure to incoming fluid into the inlet header, wherein the fluid is evenly distributed between the heat exchange elements.

Description

FIELD OF THE INVENTION

The present invention relates to heat exchangers and more particularly to evaporative condensers and coolers.

BACKGROUND OF THE INVENTION

Evaporative condensers are condensers where water is sprayed onto a heat exchanger to condense a gas into a liquid. For example, in a refrigeration system, a compressor compresses a heat exchange fluid, such as ammonia. The output of the compressor is hot, high pressure ammonia gas. The gas is provided to a condenser, where it condenses into a liquid. The liquid ammonia then passes through an expansion valve, where it drops in pressure and decreases in temperature to provide refrigeration.
In a conventional evaporative condenser, the heat exchanger for the fluid is a set of coils or tubes. The ammonia gas flows into a header and then into the coils. Condensed or liquid ammonia flows out of the coils to an outlet header.
In a cooler, the liquid disposes heat to the spraying water on the outside of the coils. The cooler uses an input header for the liquid.
It is desirable to make improvements over conventional condensers. It is also desirable to make improvements to conventional coolers.

SUMMARY OF THE INVENTION

A heat exchanger comprises inlet headers. The inlet header has a fluid inlet and an interior cavity. The outlet header has a fluid outlet. Heat exchange elements are coupled to and in fluid communication with the inlet and outlet headers. The heat exchange elements comprise first and second heat exchange elements. The first heat exchange element is coupled to the inlet header at a first location. The second heat exchange element is coupled to the inlet header at a second location. The first location is closer to the fluid inlet than is the second location. A distributor is located in the interior cavity of the inlet header between the fluid inlet and the heat exchange elements and extends between the first and second locations and the fluid inlet. The distributor causes back pressure for fluid entering the inlet header from the fluid inlet.
In accordance with one aspect, the distributor comprises a perforated wall.
In accordance with another aspect, the heat exchange elements comprise coils.
In accordance with another aspect, the inlet header comprises a pipe and the distributor comprises a perforated plate located in the pipe.
In accordance with another aspect, an evaporative condenser comprises a condenser unit. A water sprayer is located above the condenser unit. A fill section is located below the condenser unit. A basin located below the fill section. At least one fan for flowing air through the condenser unit and the fill section is provided. The condenser unit comprises an inlet header and an outlet header. The inlet header has a fluid inlet at a first location. The inlet header has heat exchange elements at locations other than the first location. A distributor is in the inlet header between the first and other locations. The distributor applies back pressure to incoming fluid in the inlet header.
In accordance with still another aspect, the distributor further comprises a perforated wall.
In accordance with still another aspect, the heat exchange elements comprise coils.
In accordance with another aspect, the inlet header comprises a pipe and the distributor comprises a perforated plate located in the pipe.
In accordance with still another aspect, the perforated plate is flat. In accordance with still another aspect, the perforated plate is curved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an evaporative condenser.

FIG. 2 is a top plan view of a portion of the heat exchanger condenser and inlet header.

FIG. 3 is a cross-sectional view of the header of FIG. 2, taken along lines III-III.

FIGS. 3A and FIG. 3B are cross-sectional views of the header, similar to FIG. 3, but of other embodiments.

FIG. 4 is a view of a distributor. FIG. 5 shows the distributor in accordance with another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The efficiency of any heat exchanger depends upon whether the incoming fluid is distributed evenly over all portions of the heat exchanger. For example, if the heat exchanger has coils arranged side by side, if the center coils receive more fluid than the other coils, then efficiency declines.
The heat exchanger described herein evenly distributes the incoming fluid throughout all portions thereof, thereby increasing efficiency. Although the heat exchanger can be a cooler, the particular application shown is in an evaporative cooler.
FIG. 1 shows an evaporative condenser 11. Sprayers 61 spray water onto a heat exchanger 13. A fan 15 draws air 17 through the wetted heat exchanger 13 to provide evaporative cooling and condensing of a fluid (typically from a gas into a liquid).
The evaporative condenser 11 has a housing 19. The heat exchanger 13 is located in the housing. Below the heat exchanger is a fill or stuffing section 21. The fill section 21 has layers that expose descending water to air flow. The layers can be made of plastic, etc. Below the fill section 21 is a basin 23 to catch the water. The housing also has a plenum 25 that communicates with the heat exchanger and the fill section. The fan 15 draws air through the heat exchanger 13, in through the fill section 21, through demisters 27 or dehydrators, into the plenum 25 and out of the housing.
The heat exchanger 13 has heat exchange elements 31 that extend from an inlet header 33 to an outlet header 35. In the preferred embodiment, the heat exchanger elements 31 are coils, however the heat exchange elements could be plates. Thus, there is a first set of coils 31A (see FIG. 2), a second set of coils 31B, a third set of coils 31C and so on. Gas enters the inlet header 33 and then the coils 31. Once in the coils, the gas condenses to a liquid. The liquid exits the coils 31 into the outlet header 35.
The inlet header 33 has an inlet pipe 37 (see FIG. 1) which delivers the gas to the inlet header 33. Likewise, the outlet header 35 has an outlet pipe 39, which removes the liquid from the outlet header. Referring to FIGS. 2 and 3, the heat exchanger and inlet header are shown. In the preferred embodiment, the inlet header 33 is a pipe with an interior cavity 41 that extends between two ends 43. The header can be circular in transverse cross-section, rectangular, etc. The inlet pipe 37 and the heat exchange elements 31 all communicate with the interior cavity 41. The heat exchange elements are connected with the inlet header by way of feed pipe stubs 38. The ends 43 of the header are closed such as with caps.
The inlet pipe 37 is typically located in the center between the ends 43. The coils 31 are spaced out along the length of the header from one end to the other end 43. Consequently, some coils are located closer to the inlet pipe 37 than other coils. For example, centrally located coils 31A-31D are closer to the inlet pipe than are end coils 31E, 31F, 31G, 31H.
In order to evenly distribute the end feed fluid to all of the heat exchange coils, a distributor 51 is provided in the interior cavity 41 of the inlet header 33. As shown in FIGS. 3 and 4, the distributor 51 is a plate with perforations 53. In the preferred embodiment, the perforations are circular holes; however the perforations could be any shape such as slots, etc. The number and size of the perforations is determined relative to the flow of the incoming gas. The distributor 51 applies a back pressure to the gas in the inlet header 33. This back pressure causes the gas to move from the central location of the inlet header out along the length of the inlet header toward the ends 43. This in turn promotes even distribution of the gas to the coils 31.
To assemble the inlet header 33, the inlet pipe 37 and feed pipes 38 are connected to the header. With the interior cavity 41 of the header exposed by way of an open end 43, the distributor plate 51 is inserted into the header interior cavity. The length of the distributor plate is slightly less than the length of the header. The distributor plate is positioned (vertically as shown in the orientation of FIG. 3) and then tacked or welded in place. The tacked points need only be at the ends and serve to immobilize the distributor inside the header. Then the end caps can be put onto the header.
Because the plate is porous, there can be gaps between the plate and the header. FIG. 5 shows another embodiment of the distributor 51A, having openings 53A in the sites adjacent to the header 33.
The distributor plate 51 is located between the inlet pipe 37 and the coils 31 so that gas flowing into the header passes through the distributor plate to flow into the coils. The distributor plate 51 can be positioned along a vertical chord, as shown by solid lines in FIG. 3. The plate is positioned closer to the feed pipes than to the inlet pipe 37. The plate 51 could be positioned closer to the inlet pipe 37, as shown by dashed lines in FIG. 3. The plate could also be positioned through the center of the header instead of along a chord.
FIG. 3 shows the distributor plate 51 as flat. The distributor plate 51 need not be flat but can be curved. FIG. 3A shows the distributor plate as concave relative to the inlet pipe 37 and can be closer to the inlet pipe (as shown by dashed lines) or closer to the feed pipes 38 (as shown in dashed lines). FIG. 3B shows the distributor plate as convex relative to the inlet pipe 37 and can be closer to the feed pipes 38 (as shown in solid lines) or to the inlet pipe 37 (as shown in dashed lines).
The outlet header is not provided with a distributor.
In operation, gas enters the header. While some gas enters the coil or coils 31A-31D adjacent to the inlet pipe 37, much of the gas flows toward the ends of the header and into the associated coils (for example 31E-31H). The coils, which are all the same size, all receive equal amounts of the gas. Thus, the heat exchanger operates more efficiently.
Although the distributor has been described in conjunction with an evaporative condenser as the preferred embodiment, it can also be used with other heat exchangers, such as coolers. The heat exchanger described above can be used as a cooler. When used as a cooler, the distributor is in the inlet header (which is now 35). Liquid enters the header and encounters back pressure due to the distributor 51. The liquid thus extends along the length of the header and enters the coils 31 as spaced along the length of the header.
The foregoing disclosure and showings made in the drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense.

Claims

1. A heat exchanger, comprising:

a) an inlet header having a fluid inlet and an interior cavity;

b) an outlet header having a fluid outlet;

c) heat exchange elements coupled to and in fluid communication with the inlet and outlet headers, the heat exchange elements comprising first and second heat exchange elements, the first heat exchange element coupled to the inlet header at a first location, the second heat exchange element coupled to the inlet header at a second location, the first location being closer to the fluid inlet than is the second location;

d) a distributor located in the interior cavity of the inlet header between the fluid inlet and the heat exchange elements and extending between the first and second locations and the fluid inlet, the distributor causing back pressure for fluid entering the inlet header from the fluid inlet.

2. The heat exchanger of claim 1 wherein the distributor further comprises a perforated wall.

3. The heat exchanger of claim 2 wherein the heat exchange elements comprise coils.

4. The heat exchanger of claim 1 wherein the inlet header comprises a pipe and the distributor comprises a perforated plate located in the pipe.

5. An evaporative condenser, comprising:

a) a condenser unit;

b) a water sprayer located above the condenser unit;

c) a fill section located below the condenser unit;

d) a basin located below the fill section;

e) at least one fan for flowing air through the condenser unit and the fill section;

f) the condenser unit comprising an inlet header and an outlet header, the inlet header having a fluid inlet at a first location, the inlet header having heat exchange elements at locations other than the first location;

g) a distributor in the inlet header between the first and other locations, the distributor applying back pressure to fluid entering the inlet header from the fluid inlet.

6. The heat exchanger of claim 5 wherein the distributor further comprises a perforated wall.

7. The heat exchanger of claim 6 wherein the heat exchange elements comprise coils.

8. The heat exchanger of claim 5 wherein the inlet header comprises a pipe and the distributor comprises a perforated plate located in the pipe.

9. The heat exchanger of claim 8 wherein the perforated plate is flat.

10. The heat exchanger of claim 8 wherein the perforated plate is curved.