US3407875A

US3407875A - Flow distributing means in heat exchangers

Info

Publication number: US3407875A
Application number: US531176A
Authority: US
Inventors: Robert L Campbell
Original assignee: United Aircraft Products Inc
Current assignee: United Aircraft Products Inc
Priority date: 1966-03-02
Filing date: 1966-03-02
Publication date: 1968-10-29
Anticipated expiration: 1985-10-29

Description

Oct. 29,1968 R P L 3,407,875

FLOW DISTRIBUTING MEANS IN HEAT EXCHANGERS Filed March 2, 1966 24 FIG-l 25 26 5 FIG-4 INVENTOR. ROBERT L. CAMPBELL HIS ATTOZNEY United States Patent m 3,407,875 FLOW DISTRIBUTING MEANS IN HEAT EXCHANGERS Robert L. Campbell, West Carrollton, Ohio, assignor to United Aircraft Products, Inc., Dayton, Ohio, a corporation of Ohio Filed Mar. 2, 1966, Ser. No. 531,176 9 Claims. (Cl. 165-174) ABSTRACT OF THE DISCLOSURE Flow distributing means for heat exchangers wherein an inlet manifold is packed for dispersed flow to the heat exchanger face and wherein deflector means at an inlet manifold inhibits by-passing flow through the center passages of the heat exchanger.

This invention relates to heat exchangers, and particularly to means for obtaining a distributed flow of fluid through a heat exchanger core providing a plurality of parallel, separated flow passages.

An object of the invention is to enforce the using of a maximum amount of the provided heat transfer surface.

Another object of the invention is to utilize a principle of diffusion at the inlet end of the heat exchanger, it being proposed to provide a diffuser readily installed in the inlet manifold.

A further object of the invention is to provide means at both the inlet and outlet ends of the heat exchanger cooperating in the achieving of flow distribution as described.

Other objects and structural details of the invention will appear from the following description, when read in connection with the accompanying drawing, wherein:

FIG. 1 is a view in longitudinal section, partly diagrammatic, of a heat exchanger in accordance with the invention, showing a diffuser installed in the inlet mani fold in accordance with a first illustrated form of the invention;

FIG. 2 is a detail view in longitudinal section of a diffuser in accordance with a second form of the invention;

FIG. 3 is a fragmentary view showing the inlet end of a heat exchanger as in FIG. 1, showing a diffuser installed therein in accordance with a third illustrated form of the invention; and

FIG. 4 is a detail plan view of a diffuser in accordance with a fourth illustrated form of the invention.

Referring to the drawing, the invention is disclosed as embodied in a tube and shell type heat exchanger. As will be recognized, however, it has general application to heat transfer devices presenting a facial surface over which it is desirable substantially equally to distribute a flowing fluid for generally uniform flow throughout the core of the heat exchanger.

In the illustrated instance the heat exchanger comprises a cylindrical shell 10 within which are spaced apart header plates or tube sheets 11 and 12. A plurality of tubes 13 (only three being here shown) are installed in openings in the plates 11 and 12. The tubes 13 are adapted to conduct a first fluid from end to end of the shell 10 in a segregated relation to the interior proper of the shell. In the shell are longitudinally spaced apart

openings

14 and 15 for the inflow and outflow of a second fluid. Inlet and

outlet bosses

16 and 17 overlie the openings 14 and 1'5 and provide for the making of flow connections to and from the heat exchanger. The described second fluid enters shell 10 by way of inlet opening 14 and flows over and around the tubes 13 to 3,407,875 Patented Oct. 29, 1968 the outlet opening where it discharges from the shell. To enforce a more thorough and repeated contact of the second fluid with the tubes 13, the interior of the vshell 10 may be fitted with baflles 18 compelling a selected number of lateral flow reversals of the fluid as it travels from opening 14 to opening 15.

In flowing over and around the tubes 13 the described second fluid is in heat transfer relation through the walls of the tubes with the described first fluid flowing through the tubes. In the illustrated instance it may be assumed that the second fluid is a transport fluid which serves a purpose elsewhere in the system of absorbing heat. As brought to the instant heat exchanger, therefore, the transport fluid is in a heated condition. The described first fluid flowing through the tubes 13 is a vaporizable coolant, for example water. The flowing second or transport fluid accordingly yields up some of its heat to the water flowing through tubes 13. In a cooled condition it is returned from the heat exchanger for reuse in the system. Ideally, a high percentage of the first fluid flowing through the tubes 13 is converted into steam therein for maximum heat absorption. For a better coefficient of heat transfer, spinner or like devices may be installed in the tubes 13. These devices tend to force a scrubbing of the tube wall interiors and inhibit straight line flow through the tube with a portion only of the flowing fluid contacting the tube wall.

The right hand end of the heat exchanger is the inlet end with respect to the described first fluid, which, for simplicitys sake, will hereinafter be called water. The left hand end of the heat exchanger, as viewed, is the outlet end. Steam, or a mixture of steam and water, is dis charged therefrom. The ends of the heat exchanger are manifolded for a controlled entrance and exit of the water and steam. At the inlet end the shell 10 has a flange 19 secured thereto. In mating contact with the flange 19 is a flange 21 to which is mounted a. generally conical manifold 22. The large end of the manifold 22 is received in and secured to the flange 21 in a facing relation to the header plate 12. The opposite or small end of the manifold is open and has installed therein a boss 23 adapted to be connected to a water supply line. Water, allowed to enter manifold 22 by way of boss 23, has access to the open ends of tubes 13 and flows through these tubes, through the shell 10 to the opposite end of the heat exchanger. At such opposite end the shell 10 has a flange 24. Another flange 25 is in mating contact therewith andmounts a generally conical manifold 26. At its small end the manifold 26 mounts a fitting 27 in which is a relatively large diameter outlet opening 20. The mixture of steam or water and steam leaving the tubes 13 enters manifold 26 and discharges through opening 20. The latter may be connected to a suitable place of discharge or, as in the illustrated instance, may be adapted merely to vent the outlet end of the heat exchanger to ambient surroundings. A distributor device 28 is installed in the small end of the manifold 26 immediately in advance of the fitting 27. It presents a blank, baffle-like surface to the header plate 11 at the mid-area of the heat exchanger. This surface, contacted by the steam and water mixture issuing from the tubes 13 in the center part of the exchanger serves as a deflector and baflie, obviating a direct flow of fluid to the outlet 20 of a kind which might encourage flow through the mid portion of the heat exchanger to the exclusion of compara- -ble flow through peripheral portions thereof. The device 20 provides openings 30 through which the steam-water mixture leaves manifold 26 to reach outlet opening 20.

The described partsof the heat exchanger are integrated into a unitary structure, as by brazing process. The header plates 11 and 12, the tubes 13 and the baflies 18 may be considered to comprise a core separately assembled and installed in the shell prior to brazing. The tubes project slightly beyond the header plates 11 and 12 and define with such plates core faces. The inlet core face, or that end facing inlet manifold 22, serves as one end of an inlet chamber, the other end of which is defined by the sloping wall of manifold 22 and by inlet boss 23. In this chamber, in accordance with the instant inventive concept is installed diffuser means distributing the incoming water in a generally uniform manner over the inlet face of the core. In the form shown in FIG. 1, the diffuser means includes a container 29 of a generally conical shape conforming to the shape of manifold 22. The base end of the container is defined by a wall 31 from which the device reduces as a sloping wall 32 to an opening 33 at the small or apex end thereof. The opening 33 is aligned with the opening at the small end of the manifold 22 and receives the inner extremity of boss 23. The arrangement is one to discharge incoming water directly into the container 29. As

indicated, the sloping wall 32 of the container conforms approximately to the correspondingly sloping wall of the manifold 22. In the assembly of the parts, the container 29 is inserted in manifold 22. When the manifold, with its attached flange 21 is mounted to the inlet end of the heat exchanger, and this may be done by bolting the

flanges

19 and 21 together, the arrangement is one to place the base wall 31 of the container into contact or substantially into contact with the projecting adjacent ends of the tubes 13. The container 29 accordingly is substantially clamped between the ends of tubes 13 and the rear sloping wall of manifold 22. The container 29 is perforated in a hole pattern designed to obviate entrapment of the water anywhere in the manifold. This includes the base wall 31. Through the freely perforated Wall 31, the liquid admitted to the interior of the container 29 has access to the inlet core face and particularly to the flow passages defined by the tubes 13.

The container 29 is filled or packed with a plurality of hard, smooth surfaced discrete objects, in the illustrated instance spherical glass beads 34. In a mutually contacting relation, the beads 34 leavesopen flow area within the container but divide such flow area into innumerable short lengths, intersecting passages extending in random directions throughout the container interior. Water admitted to the container accordingly is broken up into many ribbon-like streams which follow circuitous paths through the assembly of beads to the wall 31 and through the wall to the tubes 33. Under the pressure of continuously admitted water, a flow distribution takes place in accordance with which water is supplied substantially uniformly to the inlet core face. The heat exchanger accordingly tends to conduct water through all of its tubes 13 in an equal manner. Rapid, heavy flows through certain of the tubes, as for example those lying opposite the inlet boss 23 or those in the lower part of the head exchanger core, to the exclusion of or relative to other tubes in the core is inhibted. Maximum effective use thereby is made of all available heat transfer surface. The heat exchanger core therefore may be designed with knowledge that all of the provided surface will share more or less equally in the absorbing of the heat load, obviating the need for incorporating in the design excess heat transfer surface with its consequent extra requirements of weight and size.

In FIG. 2 another form of diffuser is shown serving the same function as the diffuser 29. In this instance, a conical wall member 35 is shaped to fit within a manifold such as the manifold 22 and is formed at its small end with an opening 36 to align with the manifold water inlet. Inwardly of the wall 35 are other spaced apart walls or

partitions

37 and 38 similarly of conical form and defining with respect to one another and with respect to the wall 35 annular spaces communicating at their one ends with the opening 36. Water entering the container as defined by the wall 35 has freedom of access to the described annular spaces as well as to the center passage defined by inner partition 38. The area of these several chambers or spaces is aproximately equal. The incoming water tends to flow in a more or less equal manner to all thereof. 7

The wall 35 and

partitions

37 and 38 all are perforated in a manner and for a purpose as described in connection with container 29. The spaces between the

members

35, 37 and 38 and within member 38 are filled with flow diffusing means, in the illustrated instance wirescreening 39. The installation of such screening may be in the form of conical screen elements nested one within another to fill the described spaces. In any event the result is to provide a flow dispersing and diffusing arrangement. The water entering the manifold accordingly is directed in three main flows, centrally through conical partition 38 and through the radially outward spaces between

partitions

37 and 38 and 37 and 35 to different radial areas of the inlet core face. The screening 39 further diffuses the flow in these areas to reach all of the communicating tubes 13. The broad or base ends of the

conical forms

35, 37 and 38 contact or substantially contact tubes in the manner that container 29 contacts tubes 13.

In the embodiment of a third form of diffuser, as shown in FIG. 3, a header plate 41 corresponding to the header plate 12 has tubes 42 therein corresponding to the tubes 13. A manifold 43 having an inlet boss 44 is mounted to the heat exchanger in the manner of manifold 22. Within the manifold 43 is a diffuser 45. The member 45 is of multi-part construction, comprising a first container portion 46 seated in the outer part of the manifold 43 and including a vertical base wall 47 adapted to seat or substantially to seat upon the projecting ends of tubes 42. Longitudinally spaced from the base Wall 47 is a back wall 48 extending transversely through the manifold interior. Superposed on the container portion 46 is a sec- 0nd container portion 49 which includes a transverse wall portion 51 longitudinally spaced from the wall 48 and occupying a position intermediate this wall and the inlet boss 44. The space between inlet boss 44 and wall 51, as well as the space between wall 51 and wall 48 and the space between wall 48 and base wall 47 are filled with a fibrous material 52, for example a product known commercially as Refrasil.

The container portions 46 and 49, including the vertical walls thereof are perforated in a hole pattern as in container 29. Water entering manifold 43. through inlet boss 44 is absorbed into the fibrous material 52 and conducted thereby through the successive

vertical walls

51, 48 and 47 to the inlet core face. The material has an inherent distributive effect, which is supplemented by the transverse successively encountered

partition walls

51, 48 and 47. Together, the fibrous material 52 and the transverse partition walls insure a well distributed movement of the liquid to the core face.

The form of diffuser shown in FIG. 4 is that of a defiector 53. It comprises a disc-like baffle portion 54 and peripherally projecting legs terminating in turned over extremities 56. The latter are adapted to achieve a mating engagement with a correspondingly turned over base extremity of a manifold, as for example as shown in'the

manifolds

22 and 43. The device 53 thereby is positioned with its central baffle portion 54 aligned with but longitudinally spaced from the central liquid inlet. Incoming liquid accordingly encounters the baffle portion 54 and is deflected thereby radially outward. The result is to prevent straight line flow from the water inlet to the core face such as might produce an undesirable channeling of fiow through tubes in the center area of the core to the exclusion of outer tubes.

I claim:

1. A heat exchanger providing inlet and outlet ends for a flowing fluid, core means including a plurality of spaced apart flow passages extending through said heat exchanger, the said inlet end of said heat exchanger defining a core face through which said flow passages open, a manifold in closing relation to said inlet end of said heat exchanger and defining a chamber one end of which is formedby said core face, said manifold having an opening therein for the inflow of said fluid into said chamber, said chamberbeing in common communication with said flow passages, the area of said opening being small in relation to the area of said core face, and diffusion means received in said manifold in intercepting relation to the incoming fluid obviating restricted flow to a portion only of the area of said core face, said diffusion means comprising a container received in said manifold, one end of said container being open and substantially seating on said core face and the other end having an opening aligning with said opening in said manifold, said container having means therein to divide the incoming fluid into multiple streams and redirect them over the core face.

2. A heat exchanger providing inlet and outlet ends for a flowing fluid, core means including a plurality of spaced apart flow passages extending through said heat exchanger, the said inlet end of said heat exchanger defining a core face through which said flow passages open, a manifold in closing relation to said inlet end of said heat exchanger and defining a chamber one end of which is formed by said core face, said manifold having an opening therein for the inflow of said fluid into said chamber, said chamber being in common communication with said flow passages, the area of said opening being small in relation to the area of said core face, and diffusion means received in said manifold in intercepting relation to the incoming fluid obviating restricted flow to a portion only of the area of said core face, said diffusion means comprising a perforated container received in said manifold and having means therein to divide and redirect the incoming fluid over the core face, said container receiving the fluid at one end and substantially contacting the core face at an opposite end.

3. A heat exchanger according to claim 2, characterized in that said container comprises a perforate wall at its said opposite end, the means in said container being confined by said wall and taking the form of discrete objects filling said container.

4. A heat exchanger according to claim 2, characterized in that said container comprises a plurality of longitudinally spaced apart perforate walls dividing the interior of said container into vertically extending compartments, the said means in said container including said walls and further taking the form of fibrous material filling said compartments.

5. A heat exchanger according to claim 2, characterized in that said container comprises a plurality of laterally spaced apart longitudinally extending partitions defining therebetween annular spaces, the said means in said container including said partitions and further taking the form of screen mesh filling said spaces.

6. A heat exchanger providing inlet and outlet ends for a flowing fluid, core means including a plurality of spaced.

apart flow passages extending through said heat exchanger, the said inlet end of said heat exchanger defining a core face through which said flow passages open, a manifold in closing relation to said inlet end of said heat exchanger and defining a chamber one end of which is formed by said core face, said manifold having an opening therein for the inflow of said fluid into said chamber, said chamber being in common communication with said flow passages, the area of said opening being small in relation to the area of said core face, and diffusion means received in said manifold in intercepting relation to the incoming fluid obviating restricted flow to a portion only of the area of said core face, said diffusion means comprising a plurality of conical partitions having their small ends extending to said opening in said manifold, said opening being opposite said core face, and having their large ends extending to said core face, said partitions being spaced apart to define therebetween annular spaces in common communication at their one ends with said opening and at their opposite ends with said core face, and means in said spaces obtaining a diffused flow therethrough. I

7. A heat exchanger providing inlet and outlet ends for a flowing fluid, core means including a plurality of ,spaced apart flow passages extending through said heat exchanger, the said inlet end of said heat exchanger defining a core face through which said flow passages open, a manifold in closing relation to said inlet end of said heat exchanger and defining a chamber one end of which is formed by said core face, said manifold having an opening therein for the inflow of said fluid into said chamber, said chamber being in common communication with said flow passages, the area of said opening being small in relation to the area of said core face, and diffusion means received in said manifold in intercepting relation to the incoming fluid obviating restricted flow to a portion only of the area of said core face, said diffusion means comprising a container received in said manifold, one end of said container having an opening aligning with said opening in said manifold, said manifold opening being opposite said core face, and the other end of said container presenting a wall perpendicular to the axis of said opening in said container and substantially seating on said core face, said wall being perforated, and a plurality of discrete spheres filling said container.

8. A heat exchanger providing inlet and outlet ends for a flowing fluid, core means including a plurality of spaced apart flow passages extending through said heat exchanger, the said inlet end of said heat exchanger defining a core face through which said flow passages open, a manifold in closing relation to said inlet end of said heat exchanger and defining a chamber one end of which is formed by said core face, said manifold having an opening therein opposite said core face for the inflow of said fluid into said chamber, said chamber being in common communication with said flow passages, the area of said opening being small in relation to the area of said core face, and diffusion means received in said manifold in intercepting relation to the incoming fluid obviating restricted flow to a portion only of the area of said core face, said diffusion means comprising a container defined by plurality of longitudinally spaced apart walls perpendicular to the axis of said manifold, said walls being perforated, said container being received in said manifold to seat again-st one end thereof while an end wall of said container substantially contacts the core face, the spaces between said walls in said container and the space between the other end wall of said container and the said opening in said manifold being filled with a fibrous ma- -terial.

9. A heat exchanger providing inlet and outlet ends for a flowing fluid, core means including a plurality of spaced apart fiow passages extending through said heat exchanger, the said inlet end of said heat exchanger defining a core face through which said flow passages open, a manifold in closing relation to said inlet end of said heat exchanger and defining a chamber one end of which is formed by said core face, said manifold having an opening therein for the inflow of said fluid into said chamber, said chamber being in common communication with said flow passages, the area of said opening being small in relation to the area of said core face, and diffusion means received in said monifold in intercepting relation to the incoming fluid obviating restricted flow to a portion only of the area of said core face, said manifold being secured to the inlet end of said heat exchanger, said diffusion means comprising a container received in said manifold and compelled by the securing of said manifold to said heat exchanger to substantially seat upon the core face, said container having an. opening to align 7 with the opening in said manifold and being filled with 1,484,749 means dilfusing the flow of fluid to said core face. 1,673,409 2,178,095 References Cited 2,602,647 5 3,196,943

UNITED STATES PATENTS Yeager 165-174 Kelley 229-27 Bowser 165-174 Miller 165-174 X Haerter 165-174 ROBERT A. OLEARY, Prineary Examiner.

A. W. DAVIS, Assistant Examiner.