EP2516940A2

EP2516940A2 - Heat exchanger and a manifold for use therein

Info

Publication number: EP2516940A2
Application number: EP10813018A
Authority: EP
Inventors: Michael Plaschkes
Original assignee: Magen Eco Energy ACS Ltd
Current assignee: Magen Eco Energy ACS Ltd
Priority date: 2009-12-21
Filing date: 2010-12-16
Publication date: 2012-10-31
Also published as: IL220484A; AU2010334448A1; US20120267085A1; WO2011077329A2; WO2011077329A3; AU2010334448B2; IL220484A0

Abstract

A heat exchanger includes a manifold and a tube array. The manifold has an internal void and walls that surround the void and merge one with the other via corners. Each wall has a middle portion that is located mid way between the corners merging with the wall and the manifold branches off to attach and communicate with the tube array at a location aside of the middle portion of one of the walls towards a corner that merges with the wall.

Description

A HEAT EXCHANGER AND A MANIFOLD FOR USE THEREIN

TECHNICAL FIELD

[001] Embodiments of the present invention relate to a heat exchanger for heating a liquid medium and to a manifold of the heat exchanger that distributes and/or gathers the liquid medium.

BACKGROUND

[002] In such a heat exchanger, liquid such as water may be distributed via the manifold into an array of plastic tubes. The water flowing in the tubes, when exposed to heat such as solar radiation, may absorb the heat and then flow onwards to be utilized.

[003] US Patent No. 7,112,297 describes a device that may be used as a solar collector that includes a plurality of hollow conduits joined between hollow manifolds. The manifold which preferably has a circular cross- section may include a subplenum adaptor that serves as a distribution chamber for uniformly distributing water to the tubes.

SUMMARY

[004] The following embodiment and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope.

[005] In an embodiment of the present invention there is provided a heat exchanger that comprises a manifold and a tube array, the manifold extends along an axis X between two ends and comprises an internal void and axially extending walls that surround the void, each given wall merging with an adjacent wall via an axially extending corner and comprising an axially extending middle portion that is located mid way between the corners merging with the given wall, the manifold branching off to attach and communicate with the tube array, wherein the branching off of the manifold forms a one piece unitary construction with the manifold and occurs at a location parallel to the middle portion of a given one of the walls and on the given wall towards a given one of the corners that merges with the given wall.

[006] Optionally, the branching off of the manifold occurs at least partially where the given wall merges with the given corner.

[007] Typically, the walls of the manifold are adapted to at least partially flex above a threshold pressure in the manifold, and the given wall merging with the given corner is adapted to flex less than the other remaining walls.

[008] Optionally, in a cross section perpendicular to the axis taken through the manifold the walls reside on an outline of a polygon.

[009] If desired, the polygon is a rectangle.

[010] Optionally, the heat exchanger may be used in a housing being of closed box-like shape and constituted by an assembly of a receiving member and an at least partially transparent cover member, the tube array being located in the housing so that solar radiation passing through the cover is at least partially absorbed by the tube array to heat the liquid in the tube array.

[011] Typically, each corner of the manifold except for the given corner is substantiality free of any reinforcing structure that projects out of the corner and extends axially therealong between the two ends of the manifold.

[012] Optionally, the branching off of the manifold occurs only at one location on the manifold on the given wall thereby leaving the remaining locations on the given wall and the remaining walls of the manifold substantially free to flex and absorb distortion due to rise of internal pressure in the manifold above a threshold pressure. [013] Typically, the heat exchanger comprises a plurality of through going holes formed in the manifold where it branches off and the tube array comprises a plurality of tubes, wherein said holes provide liquid communication between the void of the manifold and the tubes of the tube array

[014] Optionally, at least one enclosed chamber is formed in the heat exchanger where the manifold and tube array attach, said chamber communicating with at least part of the holes and with at least part of the tubes.

[015] If desired, a first part of the chamber is formed in the manifold and a second part of the chamber is formed in the tube array.

[016] Optionally, a total cross sectional area of the holes that open into the chamber is smaller than a total cross sectional area of the tubes that open into the chamber.

[017] Optionally, each given hole perpendicularly opens into the chamber at a face and in a plane perpendicular to the axis X and passing through a center of a given hole an imaginary cylindrical surface extending co-axially with the given hole has a diameter equal to a width of the face as measured in that plane, the given hole has a diameter DH and an effective wall thickness TH measured between its periphery and the cylindrical surface surrounding it, the void has an effective diameter DM that is the distance that opposing walls of the manifold are spaced apart and a given wall of the manifold has an effective-wall thickness TM, wherein a ratio of TH/DH is larger than a ratio of TM DM.

[018] Further optionally, in a plane perpendicular to the axis X and passing through a center of a given tube the given tube has a diameter DT and an effective wall thickness TT that surrounds the given tube, an inner part of the chamber at a location where a given tube opens into the chamber has an effective diameter DI as measured in the plane and a part of the tube array that is located above or below that location as measured in the plane has an effective-wall thickness TI, wherein a ratio of TI/DI is larger than a ratio of TT/DT.

[019] Even further optionally, in a plane perpendicular to the axis X and passing through a center of a given tube the given tube has a diameter DT and an effective wall thickness TT that surrounds the given tube, the void has an effective diameter DM that is the distance that opposing walls of the manifold are spaced apart and a given wall of the manifold has an effective-wall thickness TM, wherein a ratio of TM DM is larger than a ratio of TT DT.

[020] In an embodiment of the present invention there is also provided a heat exchanger comprising a manifold and a tube array, the manifold extends along an axis X between two ends and comprises an internal void and axially extending walls that surround the void, each given wall merging with an adjacent wall via an axially extending corner and comprising an axially extending middle portion that is located on the given wall mid way between the corners merging with the given wall, the manifold being adapted to flex under a rise of internal pressure in the manifold above a threshold pressure with a maximum flex being adapted to occur at least at middle portions of walls with no branching off structures, and the manifold branching off to attach and communicate with the tube array at a single location that is parallel to the middle portion of a given one of the walls and on the given wall towards a given one of the corners that merges with the given wall.

[021] Optionally, the branching off of the manifold forms a one piece unitary construction with the manifold.

[022] Typically, the branching off of the manifold occurs at least partially where the given wall merges with the given corner.

[023] In addition to the exemplary aspects and embodiment described above, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed descriptions. BRIEF DESCRIPTION OF THE FIGURES

[024] Exemplary embodiments are illustrated in referenced figures. It is intended that the embodiments and figures disclosed herein are to be considered illustrative, rather than restrictive. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying figures, in which:

[025] Figs. 1 and 2 schematically show respectively a perspective view and an exploded perspective view of an optional use of a heat exchanger in accordance with an embodiment of the present invention in a solar collector;

[026] Fig. 3 schematically shows a perspective view on an upper part of the heat exchanger incorporating three manifolds in accordance with an embodiment of the present invention attached each to a tube array;

[027] Fig. 4 schematically shows a perspective view of one of the manifolds attached to a tube array;

[028] Fig. 5 schematically shows a perspective front view of the manifold showing a side of the manifold that branches off for attachment to a tube array;

[029] Fig. 6 schematically shows a perspective view of the tube array from a side that attaches to the manifold;

[030] Fig. 7 schematically shows a perspective back view of the manifold;

[031] Fig. 8 schematically shows a cross sectional view of the manifold;

[032] Fig. 9 schematically shows a cross sectional view of the manifold attached to the tube array; and

[033] Fig. 10 schematically shows a cross sectional view of the manifold attached to the tube array when subjected to a rise of pressure in the heat exchanger.

[034] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated within the figures to indicate like elements.

DETAILED DESCRIPTION

[035] Attention is first drawn to Figs 1 and 2. A heat exchanger 10 in accordance with an embodiment of the present invention is formed of three upper and three lower manifolds 12 and three tube arrays 14 that extend therebetween. The heat exchanger 10 may optionally be used in a solar collecting system 16 that has a closed box like housing that includes a receiving member 18 and a transparent cover member 20 and solar radiation passing through the cover member 20 may be absorbed by the heat exchanger 10 to heat liquid flowing therein.

[036] The manifolds 12 and tube arrays 14 of the heat exchanger 10 are optionally made of plastics that are stabilized for outdoor usage such as thermoplastic polypropylene copolymer and optionally said plastics have a glass transition temperature that is below zero degrees Celsius. In embodiments of the present invention the heat exchanger 10 may be used in other types of systems and/or applications such as agricultural root zone heating, chemical heat exchanging systems, geothermal ground source heat pumps, pond heat exchanging systems, ice storage heat exchanging systems, (etc.). It should be noted that directional terms appearing throughout the specification and claims, e.g. "forward", "rear", "up", "down" etc., (and derivatives thereof) are for illustrative purposes only, and are not intended to limit the scope of the appended claims. In addition it is noted that the directional terms "down", "below" and "lower" (and derivatives thereof) define identical directions.

[037] Attention is now drawn to Figs. 3 and 4. Each manifold 12 extends along an axis X between two axial ends 22 and has an internal axially extending void 24 that opens out of the manifold 12 at the two ends 22. The void 24 is surrounded by four axially extending optionally planar walls 26 of the manifold 12 and each wall 26 merges via an axially extending corner 28 with an adjacent wall 26 that extends perpendicularly thereto. Each given wall 26 has an axially extending middle portion 27 that is located mid way between the two corners 28 that are located on both sides of the given wall 26 (middle portions 27 are indicated in Fig, 8) and under internal pressure in the void 24 each wall 26 that is free of any branching off and/or reinforcing structures is adapted to flex most at its middle portion 27.

[038] The manifold 12 optionally branches off to attach and form liquid communication with a tube array 14 of the heat exchanger 10 at a location parallel to the middle portion 27 of a given one of the walls 26 towards a given one of the corners 30 that merges with the given wall 26. Optionally, that branching off of the manifold 12 occurs at a location where the given one of the walls 26 merges with the given one of the corners 28 of the manifold 12. Said branching off of the manifold 12 forms a structure that is preferably integrally formed with the manifold 12 to form a one piece unitary construction with the manifold 12 that reinforces the manifold 12 at a location where through going liquid conducting passages that are formed through the manifold 12 typically weaken the manifold 12.

[039] In an embodiment of the present invention, the branching off of the manifold 12 at the merge with a given one of the corner 28 reinforces that corner 28 (hereinafter optionally referred to as "reinforced corner") while the remaining other corners 28 of the manifold 12 are left free of any reinforcing structures (hereinafter optionally referred to as "free corners"). In embodiments of the present invention the heat exchanger 10 may include a single tube array 14 extending between a pair of manifolds 12 or any given number of tube arrays 14 and corresponding pairs of manifolds 12 as required in the application in which the heat exchanger 10 is used. For example, in the embodiment shown in Fig. 1 the heat exchanger 10 includes three tube arrays 14 that extend between three pairs of manifolds 12.

[040] Attention is drawn to Fig. 5. A port 30 of the manifold 12 that projects out of the manifold 12 where it branches off to attach and communicate with the tube array 14 forms at least part of the reinforcement of the reinforced corner 28 by extending along that corner 28 between the two axial ends 22 of the manifold 12. The port 30 has a series of recesses 32 formed at its outer side that is distal of the manifold 12. Each recess 32 has a floor 33 and a raised wall 35 that extends along a perimeter of the floor 33 and a portion of each wall 35 that is located between adjacent recesses 32 acts as a partition 34 between those recesses 32.

[041] Attention is additionally drawn to Figs. 7 and 8. An axially extending optional rib 36 of the manifold 12 extends along an inner side of the reinforced corner 28 within the void 24 between the two axial ends 22 of the manifold 12. The optional rib 36 acts as an additional optional structure that reinforces the reinforced corner 28 and a plurality of through going liquid conducting passages or holes 38 extend through the rib 36, port 30 and reinforced corner 28. Each hole 38 opens into the void 24 of the manifold 12 at the rib 36 and opens out of the manifold 12 into a given one of the recesses 32 of the port 30 at the floor 33 of the given recess 32. As best seen in Fig. 5, each recess 32 acts as a basin into which several axially adjacent holes 38 collect.

[042] Attention is drawn to Fig. 6. The tube array 14 has a plurality of flexible plastic tubes 40 that are attached at both ends to an inner side of an insert 42 of the tube array 14 and the insert 42 has a series of recesses 44 formed on its outer side with a series of partitions 46 being spaced along the insert 42 between adjacent recesses 44.

[043] Attention is now drawn to Figs. 4 and 9. In the heat exchanger 10, the manifold 12 is attached at an outer face of its port 30 by optionally heat bonding to an outer face of the insert 42 of the tube array 14. Each recess 32 in the port 30 of the manifold 12 meets in the heat exchanger 10 a corresponding recess 44 of the insert 42 to form an enclosed chamber 48 that is adapted to communicate via a group of axially adjacent holes 38 on the one hand with the void 24 of the manifold 12 and via a group of axially adjacent tubes 40 on the other hand with the tube array 14.

[044] Attention is specifically drawn to Fig. 9. In the manifold 12 the following features may be defined in a cross section perpendicular to the axis X that passes through a center of each given hole 38. An imaginary cylindrical surface C may be defined extending co-axially about each given hole 38 with the diameter of the cylindrical surface C being equal to a width K of the floor 33 as measured in the cross section. An effective-wall thickness TH around each given hole 38 may be defined between a periphery of the given hole 38 and the cylindrical surface C that surrounds that given hole 38 and each given hole 38 may be defined as having an internal diameter DH. The void 24 of the manifold 12 may be defined as having an effective-diameter DM that is the distance that the inner faces of opposing walls 26 of the manifold 12 are spaced apart and the walls 26 of the manifold 12 may be defined as having an effective-wall thickness TM.

[045] In the tube array 14 the following features may also be defined in a cross section perpendicular to the axis X that may pass through a center of each given tube 40. Each given tube 40 may be defined as having an internal diameter DT and a wall thickness TT that surrounds the given tube 40 and an inner part of each recess 44 of the insert 42 at a location where a given tube 40 opens into the recess 44 may be defined as having an effective diameter DI as measured in the cross section and a part of the insert 42 that is located above or below that location as measured in the cross section may be defined as an effective-wall thickness TI.

[046] Optionally, a ratio of TH / DH may be larger than a ratio of TM / DM so that the manifold 12 may have a pressure rating at the holes 38 that is higher than the void 24 and thereby may be designed to better withstand internal pressures at the holes 38 in relation to the void 24.

[047] Further optionally, a ratio of TI / DI may be larger than a ratio of TT / DT so that the tube array 14 may have a pressure rating at the insert 42 that is higher than the tubes 40 and thereby may be designed to better withstand internal pressures at the insert 42 in relation to the tubes 40.

[048] Yet further optionally, a ratio of TM / DM may be larger than a ratio of TT / DT so that the heat exchanger 10 may have a pressure rating at the void 24 that is higher than the tubes 40 and thereby may be designed to better withstand internal pressures at the void 24 in relation to the tubes 40.

[049] The diameters DH of the holes 38 in the manifold 12 are optionally smaller than the diameters DT of tubes 40 in the tube array 14 so that the total cross sectional area of the holes 38 is optionally smaller than the total cross sectional area of the tubes 40. In some embodiments of the present invention, the smaller cross sectional area of the holes 38 may act to reduce the flow out of the manifold 12 thereby assisting to uniformly distribute liquid along the manifold 12.

[050] Attention is now drawn to Figs. 2 and 9. In different embodiments of the heat exchanger 10 various flow patterns may exist. For example in an embodiment of the heat exchanger 10, liquid flowing downstream optionally into the voids 24 of the upper manifolds 12 optionally branches off out of the upper manifolds 12 via the holes 38 into the chambers 48 that are associated with the upper manifolds 12. From there, the liquid may flow downstream into the tubes 40 of the tube arrays 14 where most of the heat exchange between the liquid located in the tubes 40 and the environment outside of the tubes 40 is adapted to occur. The liquid flowing downstream and out of the tube arrays 14 reaches the chambers 48 associated with the lower manifolds 12 and from there via the holes 38 reaches the voids 24 of the lower manifolds 12 and optionally flows out of the heat exchanger 10 for utilization.

[051] During use, the heat exchanger 10 may be subjected to varying forces that are imposed thereupon by the liquid that is located therein. The liquid in the heat exchanger 10 may reach for example a temperature of about 80 to 90 degrees Celsius and a pressure of about 6 to 7 atmospheres when heated for example by solar radiation and on the other hand may exhibit freezing during cold weather conditions. Liquid such as water that may be used in a heat exchanger 10 may for example expand and form an increase in volume of about 9% when freezing under atmospheric pressure thereby imposing considerable forces upon the heat exchanger 10 that may act to distort the heat exchanger 10.

[052] Attention is now drawn to Fig. 10. In some embodiments of the present invention, an increase of pressure in the void 24 that is indicated in this figure by small arrows 23 may act to distort the portions of the manifold 12 surrounding the void 24. In the heat exchanger 10 in accordance with some embodiments of the present invention, the reinforced corner 28 of the manifold 12 is reinforced to such an extent that the structured "handicap" that is formed therein by the through going holes 38 which may weaken the ability of the corner 28 to withstand stress is strengthened and reinforced by the additional reinforcing structures that are associated therewith.

[053] The branching off structure of the port 30, the insert 42 structure of the tube array 14 that is bonded to the port 30, and the optional rib 36 are examples of such structures that may be associated with the reinforced corner 28 and may each independently improve its ability to withstand stress and exhibit less distortion. As a result, under internal pressure in the void 24, the portions of the manifold 12 more distal of the reinforced corner 28 are adapted to flex and exhibit distortion to a larger extent in relation to portions of the manifold 12 more proximal to the reinforced corner 28. Optionally, the free corners 28 of the manifold 12 are deliberately left free of any substantial reinforcing structures that extend axially therealong between the two ends 22 of the manifold 12 and project out of the corners 28 so that they may be free to absorb as much distortion as possible and thereby limit any stress that may be imposed upon the reinforced corner 28 due to a rise in the internal pressure in the manifold 12.

[054] In an embodiment, under internal pressure in the void 24 the given wall 26 from which the branching off occurs or the two walls 26 merging via the reinforced corner 28 is/are adapted to flex to a lesser extent and exhibit less distortion in relation to the remaining walls 26 of the manifold 12 that are more distal of the given wall 26 or reinforced corner 28.

[055] In the description and claims of the present application, each of the verbs, "comprise" "include" and "have", and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb.

[056] Although the present embodiment has been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the scope of the invention as hereinafter claimed.

Claims

CLAIMS:

1. A heat exchanger comprising a manifold and a tube array,

the manifold extending along an axis X between two ends and comprising an internal void and axially extending walls that surround the void, each given wall merging with an adjacent wall via an axially extending corner and comprising an axially extending middle portion that is located mid way between the corners merging with the given wall, the manifold branching off to attach and communicate with the tube array, wherein the branching off of the manifold forms a one piece unitary construction with the manifold and occurs at a location parallel to the middle portion of a given one of the walls and on the given wall towards a given one of the corners that merges with the given wall.

2. The heat exchanger according to claim 1, wherein the branching off of the manifold occurs at least partially where the given wall merges with the given corner.

3. The heat exchanger according to claim 2, wherein the walls of the manifold are adapted to at least partially flex above a threshold pressure in the manifold, and wherein the given wall merging with the given corner is adapted to flex less than the other remaining walls.

4. The heat exchanger according to claim 1, wherein in a cross section perpendicular to the axis taken through the manifold the walls reside on an outline of a polygon.

5. The heat exchanger according to claim 4, wherein the polygon is a rectangle.

6. The heat exchanger according to claim 1 for use in a housing being of closed box-like shape and constituted by an assembly of a receiving member and an at least partially transparent cover member, the tube array being located in the housing so that solar radiation passing through the cover is at least partially absorbed by the tube array to heat the liquid in the tube array.

7. The heat exchanger according to claim 2, wherein each corner of the manifold except for the given corner is substantiality free of any reinforcing structure that projects out of the corner and extends axially therealong between the two ends of the manifold.

8. The heat exchanger according to claim 1, wherein the branching off of the manifold occurs only at one location on the manifold on the given wall thereby leaving the remaining locations on the given wall and the remaining walls of the manifold substantially free to flex and absorb distortion due to rise of internal pressure in the manifold above a threshold pressure.

9. The heat exchanger according to claim 1 comprising a plurality of through going holes formed in the manifold where it branches off and the tube array comprises a plurality of tubes, wherein said holes provide liquid communication between the void of the manifold and the tubes of the tube array.

10. The heat exchanger according to claim 9 comprising at least one enclosed chamber that is formed in the heat exchanger where the manifold and tube array attach, said chamber communicating with at least part of the holes and with at least part of the tubes.

11. The heat exchanger according to claim 10, wherein a first part of the chamber is formed in the manifold and a second part of the chamber is formed in the tube array.

12. The heat exchanger according to claim 10, wherein a total cross sectional area of the holes that open into the chamber is smaller than a total cross sectional area of the tubes that open into the chamber.

13. The heat exchanger according to claim 10, wherein each given hole perpendicularly opens into the chamber at a face and in a plane perpendicular to the axis X and passing through a center of a given hole an imaginary cylindrical surface extending co-axially with the given hole has a diameter equal to a width of the face as measured in that plane, the given hole has a diameter DH and an effective wall thickness TH measured between its periphery and the cylindrical surface surrounding it, the void has an effective diameter DM that is the distance that opposing walls of the manifold are spaced apart and a given wall of the manifold has an effective-wall thickness TM, wherein a ratio of TH/DH is larger than a ratio of TM DM.

14. The heat exchanger according to claim 10, wherein in a plane perpendicular to the axis X and passing through a center of a given tube the given tube has a diameter DT and an effective wall thickness TT that surrounds the given tube, an inner part of the chamber at a location where a given tube opens into the chamber has an effective diameter DI as measured in the plane and a part of the tube array that is located above or below that location as measured in the plane has an effective- wall thickness TI, wherein a ratio of TI DI is larger than a ratio of TT/DT.

15. The heat exchanger according to claim 10, wherein in a plane perpendicular to the axis X and passing through a center of a given tube the given tube has a diameter DT and an effective wall thickness TT that surrounds the given tube, the void has an effective diameter DM that is the distance that opposing walls of the manifold are spaced apart and a given wall of the manifold has an effective- wall thickness TM, wherein a ratio of TM/DM is larger than a ratio of TT DT.

16. A heat exchanger comprising a manifold and a tube array,

the manifold extending along an axis X between two ends and comprising an internal void and axially extending walls that surround the void, each given wall merging with an adjacent wall via an axially extending corner and comprising an axially extending middle portion that is located on the given wall mid way between the corners merging with the given wall, the manifold being adapted to flex under a rise of internal pressure in the manifold above a threshold pressure with a maximum flex being adapted to occur at least at middle portions of walls with no branching off structures, and the manifold branching off to attach and communicate with the tube array at a single location that is parallel to the middle portion of a given one of the walls and on the given wall towards a given one of the corners that merges with the given wall.

17. The heat exchanger according to claim 16, wherein the branching off of the manifold forms a one piece unitary construction with the manifold.

18. The heat exchanger according to claim 17, wherein the branching off of the manifold occurs at least partially where the given wall merges with the given corner.