DUAL PASS OPPOSED (REVERSE) FLOW COOLING COIL WITH IMPROVED PERFORMANCE

Abstract

A dual pass heat exchanger for cooling and dehumidifying an airstream has adjacent passes for air flow in which air flow is in opposite directions being counter-flow and parallel-flow passes. A cooling coil contains flowing chilled liquid refrigerant extending through all of the passes, and the coiling coil has fins on outer surfaces thereof for promoting efficient thermal transfer, whereby density of the fins in the counter-flow passes is greater than density in the parallel-flow passes, whereby fin density is varied in fin style, locational density, thickness and/or depth.

Claims

1. A dual pass heat exchanger for cooling and dehumidifying an airstream comprising: said heat exchanger having adjacent passes for air flow in which air flow is in opposite directions being counter-flow and parallel-flow passes; a cooling coil containing flowing chilled liquid refrigerant extending through all of said passes, said coiling coil having fins on outer surfaces thereof for promoting efficient thermal transfer; and density of said fins in said counter-flow passes being greater than density in said parallel-flow passes.

2. The heat exchanger of claim 1 in which said refrigerant is chilled water.

3. The heat exchanger of claim 1 in which said passes are parallel to each other.

4. The heat exchanger of claim 3 having a plenum area at one end of said, heat exchanger, said air flow reversing direction in said plenum in moving from one pass to adjacent passes.

5. The heat exchanger of claim 4 in which said plenum has an opening for draining condensate.

6. The heat exchanger of claim 1 wherein said fins of greater density in said counter-flow passes are provided closer together.

7. The heat exchanger of claim 1 wherein said fins of greater density in said counter-flow passes occupy more space in the direction of airflow, thereby increasing air velocity and turbulence.

8. The heat exchanger of claim 1 wherein said fins of greater density in said counter-flow passes are thicker and occupy more space in the direction of airflow than said fins of less density in said parallel flow passes, thereby providing increased turbulence and increased air velocity.

9. The heat exchanger of claim 1 wherein said fins are only in said counter-flow passes and said parallel flow passes are provided empty of any fins.

10. A method for cooling and dehumidifying an airstream comprising the steps of: providing a heat exchanger with multi-passes for air flow, adjacent passes in which air flow is in opposite directions being counter-flow and parallel-flow passes; providing a cooling coil containing flowing chilled liquid refrigerant extending through all of said passes, said coiling coil having fins on outer surfaces thereof for promoting efficient thermal transfer; and providing a density of said fins in said counter-flow passes greater than density in said parallel-flow passes.

11. The method of claim 10 in which said refrigerant is chilled water.

12. The method of claim 10 in which said passes are arranged to be parallel to each other.

13. The method of claim 13 in which a plenum area is provided at one end of said heat exchanger for reversing direction of said air flow in said plenum in moving from one pass to adjacent passes.

14. The method of claim 13 in which an opening is provided in said plenum for draining condensate.

15. The method of claim 10 further comprising the step of providing, said fins of greater density in said counter-flow passes closer together.

16. The method of claim 10 further comprising the step of providing said fins of greater density in said counter-flow passes to occupy more space in the direction of airflow, thereby increasing air velocity and turbulence.

17. The method of claim 10 further comprising the step of providing said fins of greater density in said counter-flow passes being thicker and occupying more space in the direction of airflow than said fins of less density in said parallel flow passes, thereby providing increased turbulence and increased air velocity.

18. The method of claim 10 further comprising the step of providing said fins are only in said counter-flow passes and said parallel flow passes being provided empty of any fins.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention can best be understood in connection with the accompanying drawings. It is noted that the invention is not limited to the precise embodiments shown in drawings, in which:

[0025] FIG. 1 is a side diagrammatic view of a Prior Art heat exchanger above a chilled water cooling coil with air flow fins, with equal Finned Media on both the counter-flow and parallel-flow passes.

[0026] FIG. 2 is a side diagrammatic view of the present invention showing a heat exchanger above a chilled water cooling coil with air flow fins, where the Finned Media is improved on counter-flow passes, and disimproved on parallel-flow passes.

[0027] FIG. 3 is an enlarged side internal elevation of the cooling coil of FIG. 2 showing clearly the different fin density in the counter-flow regions as compared to that of the parallel-flow regions of air flow.

[0028] FIG. 4 is a perspective view showing improved performance of the heat exchanger above a refrigerant cooling coil, wherein a high fin density is provided on counter-flow passes and a low fin density is provided on parallel-flow passes, wherein the counter-flow pass regions alternate with the parallel-flow regions.

DETAILED DESCRIPTION OF THE DRAWINGS

[0029] A prior art diagrammatic view of a heat exchanger above a chilled water cooling coil is shown in FIG. 1. The bottom section of FIG. 1 shows a side elevation with a cooling coil 1. A top view of coil 1 is shown above the bottom section (and in registration with it). The fins 7, attached to coolant tubes 4, have the same Finned Media on both counter-flow and parallel-flow passes. Chilled water enters at 2 and leaves at 3. Air flow is indicated by wide arrows 15 and is shown entering and leaving the plenum area 9 under coil 1. Parallel-flow and counter-flow air paths are being separated by dividers 6. Above coil 1 is a line of adjacent air heat exchangers 5. Condensate is shown as 11 leaving the plenum 9 area.

[0030] A diagrammatic view of the present invention is shown in FIG. 2. The format of FIG. 2 matches that of prior art FIG. 1 to clearly distinguish the improvement. Here again a top view of chilled water cooling coil 1 is shown above, the side elevation of the dual pass system. Parallel-flow and counter-flow air paths are being separated by dividers 6. The change is that the finned Media of the counter-flow passes has been improved relative to the finned Media of the parallel-flow passes. Finned Media 17 of the counter-flow regions is shown next to the decreased finned Media 18 of the parallel-flow sections. The better control of pressure drops and heat transfer of the systems according to FIG. 2 improve thermal and overall efficiency.

[0031] A sectional view of the present invention is shown in FIG. 3 for clarity. The fins 7 are shown as vertical line segments attached to coolant tubes 4. The spacing of fins 7 can be seen more clearly in this view. Fins 7 are spaced much closer together in counter-flow regions 17 and are spaced farther apart in parallel-flow regions 18. While shown with lower fin density in regions 18 in this view, as mentioned earlier these parallel-flow regions could be totally unfinned.

[0032] The perspective view (FIG. 4) of a refrigerant coil 25 with alternating low and high fin densities shows that a similar technique can be used on refrigerant coils. The high fin density regions are in registration with counter-flow regions while the low fin density regions are in registration with parallel-flow regions.

[0033] In the foregoing description, certain terms and visual depictions are used to illustrate the preferred embodiment. However, no unnecessary limitations are to be construed by the terms used or illustrations depicted, beyond what is shown in the prior art, since the terms and illustrations are exemplary only, and are not meant to limit the scope of the present invention.

[0034] It is further known that other modifications may be made to the present invention, without departing the scope of the invention.