CA1065219A

CA1065219A - Heat exchange panel

Info

Publication number: CA1065219A
Application number: CA248,729A
Authority: CA
Inventors: Charles A. Kleine; Verne L. Middleton
Original assignee: Olin Corp
Current assignee: Olin Corp
Priority date: 1975-05-02
Filing date: 1976-03-23
Publication date: 1979-10-30
Also published as: BR7602633A; YU40136B; RO80999A; JPS51134456A; NO761174L; SE7604985L; AU1255476A; FR2309819B1; MX145104A; DE2619372A1; FR2309819A1; HU172858B; DE2619372C2; TR19700A; GB1541242A; DD125357A5; RO80999B; IT1058224B; JPS5949518B2; NO142050B

Abstract

ABSTRACT OF THE DISCLOSURE
A heat exchange panel having a desired system of internal tubular passageways is described, wherein the internal passageways include opposed headers connected by connecting portions of said passageways extending there-between. The headers define an angle of at least 91° with respect to the direction of flow of heat exchange medium in the heat exchange panel. The headers are designed to pro-vide uniform fluid distribution and to enable efficient drainage of fluid from the unit, including any entrapped gases.

Description

~0652~9 BAC~GROUND OF THE INVENTION
This invention relates to metal panels having a desired system of internal tubular passageways for a heat exchange medium, wherein the internal tubular passageways are dis-posed between spaced apart portions of the thickness of the panel. The panels of the present invention find particular applicatlon in devices for utilizing solar energy and, particularly, to solar energy adsorbing devices for eleva-ting fluid temperature.
It ls well ~nown that the radiation of the sun can be collected as a source of energy for heating or cooling or for direct conversion to electricity. Heat~ng and cooling depend upon collection of rays of solar energy in a fluid heat transfer system. The heated fluid is pumped or allowed to flow to a place of utilization for the thermal energy it has acquired.
In certain areas of the world, solar energy is the most abundant form of available energy if it could be harnessed economically. Even in more developed areas of the world, the economic harnessing Or solar energy would provide an attractive alternative to the use of fossil fuels ~or energy generation.
It is a particular ob~ect of the present inventlon to provide a metal panel for use in a solar energy collector system which enables the efficient and economical use of solar energy.
It is a particular ob~ect of the present invention to provide a metal panel as aforesaid ~rhich is efficiently designed to allow maximum utilization of internal passage-way systems in a solar energy collector.

Further ob~ects and advantages of the present invention will appear hereinafter.
SUMMARY OF-THE INVENTION
In accordance with the present invention a highly efficient heat exchanger is provided which is particularly suited for use as a solar collector panel. In the broadest embodiment the heat exchanger of the present invention has a desired system of tubular passageways for a heat exchange medium defining opposed headers connected by connecting portions of said passageways extending therebetween, said passageways having entry and exit portions extending from ~
said headers to provide ingress and egress openings for said ~-heat exchange medium, wherein said headers define an angle of at least 91 with respect to the direction of flow of said heat exchange medium in said heat exchanger, normally with respect to the entry and exit portions extending from said headers. In the preferred embodiment, the metal panel or plate of the present invention has a desired system of internal tubular passageways for a heat exchange medium, wherein said passageways are disposed between spaced apart portions of the thickness of the panel and define opposed headers connected by connecting portlons of sald passageways extending therebetween. The connecting portions of sald passageways extend in said panel in a direction transverse to and interconnecting said headers. Generally the con-necting portions extend longitudinally in said panel, although naturally the connecting passageways may extend transversely if desired. The internal passageways are provided with entry and exit portions extending from the headers to opposed edges of the panel in order to provide . : - . , ~ .

1065Z~9 ingress and egress openings for the heat exchange medium.
The headers define an angle of at least 91, and general y from 92 to 100 with respect to the direction of flow of said heat exchange medium and normally with respect to the entry and exit portions, respectively, extending therefrom. -In addition, preferably the headers include portions of the metal which are bonded together to provide increased header strength, improve fluid flow control and directionality and provide interruption in the flow of the heat exchange medium.
In accordance with the present invention the foregolng panel achieves significant advantages. The defined angle between the headers and the entry and exit portions, respec-tively, provides a generally inclined header containing bonded portions which is so designed as to provide uniform fluid distribution. In addition, the inclined header of the present invention provides a means to efficiently drain fluid from the unit and also to provide a drain for collected gases, thereby preventing air locks. In addition to the foregoing, the bonded portions in the headers provide -increased header strength, improve fluid flow control and directionality and provide interruption in the flow of the heat exchange medium and materially aid in obtaining uniform fluid distribution throughout the unit.
As indicated above, the preferred embodiment utilizes a metal panel having a system of internal fluid passageways, conventionally painted black, as will be described in more detail hereinbelow, however, the concepts of the present invention may also be advantageously utilized in heat exchangers generally, such as, for example, using extrusions.
Since the concepts of the present invention are particularly lO~SZl9 advantageous in metal panels having a system of internal fluid passageways, the present invention will be specifically ::
. described hereinbelow utilizing this type of system.
In accordance with a specific embodiment of the invention, there is provided a heat exchange panel having a -~
system of internal tubular passageways defining opposed headers ~ :
connected by connection portions of said passageways extending therebetween, said headers having entry and exit portions - extending therefrom to opposed edges of said panel to provide ~;
ingress and egress openings for said heat exchange medium, ~
said entry and exit portions having a central axis, wherein ~-said headers include a plurality of interruption portions to provide interruption in the flow of said heat exchange medium and wherein said headers possess outer edges defining the perimeter thereof adjacent the entry or exit portions, respect-ively, extending therefrom, and wherein the apex of the perimeter of said outer edges defines an external angle of at least 91 with respect to the central axis of said entry and exit portions, respectively, to provide uniform fluid distribu-tion and enable efficient drainage of fluid from the heat exchanger.
In accordance with a further embodiment of the invention, there is provided a heat exchange panel having a desired system of internal tubular passageways for a heat exchange medium disposed between spaced apart portions of the thickness of said panel, said passageways defining opposed headers connected by connection portions of said passageways extending therebetween, wherein said heat exchange medium flows from header to header through said connecting portions, said headers having entry and exit portions extendin~ there~rom to opposed edyes of said panel to provide ingress and egress openings for said heat exchange medium, said entry and exit ~, :

., ~ , .
. .: . : . . : ' ' . : .

portiOns having a central axis, wherein said headers include a plurality of portions of said metal which are bonded together to provide interruption in the flow of said heat exchange medium and wherein said headers possess outer edges defining the perimeter thereof adjacent the entry or exit portions, respectively, extending therefrom, and wherein the apex of the perimeter of said outer edges defines an external angle of at least 91 and less than 100 with respect to the central axis of said entry and exit portions, respectively, to provide uniform fluid distribution and enable efficient drainage of fluid from the heat exchanger, wherein a first plurality of said panels are connected by a common manifold communicating with the entry portions of each of said panels for distributing said heat exchange medium into said first plurality of panels and wherein a common collection manifold communicates with the exit portions of each of a second plurality of said panels for collection of said heat exchange medium from each of said second plurality of said panels.
In accordance with a still further embodiment of the invention, there is provided a heat exchange panel for use in a solar energy collector system possessing a system of internal tubular passageways defining opposed headers, said headers connected by a plurality of spaced parallel individual connect-ing portions of said passageways extending therebetween, said headers having entry and exit portions extending therefrom to opposed edges of said panel to provide ingress and ~gress open-ings for said heat exchange medium, each of said entry and exit portions having a central axis, said headers possessing outer boundaries defining the perimeter thereof, said boundaries lying adjacent the apex of said perimeter defining an external angle of at least 91 with respect to the central axis of the most adiacent entry or exit portions, said angle taken in the plane -4a-.

10652~9 containing said panel, wherein said headers are triangular in shape and possess a plurality of parallel fluid channels communicating with the connecting portions of said passageways and running in a direction substantially transverse thereto wherein said parallel channels are defined by a plurality of aligned bonded portions located within said headers assisting in the distribution of said heat exchange medium to the respect-ive connecting portions.
The present invention will be more fully described in the ensuing specification.
; BRIEF DESCRIPTION OF_?HE ~RAWINGS
Figure 1 is a diagram showing schematically the manner in which the panels of the present invention can be employed;
Figure 2 is a perspective view of a sheet of metal having a pattern of weld inhibiting material applied to a surface thereof, Figure 3 is a perspective view of a composite metal blank wherein a second sheet of metal is superimposed on the sheet of metal shown in Figure 2 with the pattern of weld inhibiting material sandwiched therebetween;
Figure 4 is a schematic perspective view showing the sheets of Figure 3 bein~ welded together while passing through~
a pair of mill rolls, Figure 5 is a top view showing the panel of the present invention having internal tubular passageways disposed between spaced apart portions of the thickness of the panel in the areas of the weld inhibiting material;
Figure 6 is a sectional view taken along lines 6-6 of Figure 5;
Figure 7 is an alternate view showing a variation in the tube configuration similar to the view of Figure 6; and Figures 8, 9, 10, ll, 12 and 13 are top views showing ~r-~, variations in the panel design of the present invention.
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DETAILED DESCRIPTION
The panels of the present invention are preferably utilized in a solar heating system as shown in Figure 1 wherein a plurality of panels of the present invention 10 are mounted on roof 11 of building 12 with conduits 13 and 14 connected in any convenient fashion to the equipment in the building, with the connections not shown. Thus, for example, cold water may go into conduit 13 from the building 12 by means of a conventional pump or the like.
The water flows along common manifold 13a and is distributed into panels 10. The water flows through panels 10, is ;~
heated by means of solar energy, is collected in common manifold 14a, and flows into conduit 14. The heated water is then stored or utilized in a heat exchange system inside the building in a known manner. Naturally, if desired, the water flow may be reversed with the cold water entering via conduit 14 and collected via conduit 13. Alternatively, the solar heating unit of the present invention may be used or placed in any suitable environment, such as on the ground with suitable fasteners to prevent displacement by wind or gravity. The solar heating unit of the present invention may be used for resldential heating purposes, such as in providing hot water in a residential environment. For example, three panels of the present invention having dimensions of 8 feet X 4 feet would efficiently supply an average household of four with hot water for home use.
Alternatively, the solar panels of the present invention may be conveniently used for heating water for swimming pools or for preheating water for domestic gas or oil fired domestic hot water heaters. The fluid is preferably -retained in a closed system with the water in the system - heated in the solar unit and delivered into an insulated cistern or container so that the heated fluid may be stored up during sunshine for use on cool cloudy days or at night when the heating of the fluid in the panel will not be of sufficient degree to provide the desired heat at the point of use.
A thermostat not shown is desirably installed at the top of the solar heater and this thermostat may be set to turn on a circulating pump whenever the temperature reaches a predetermined reading. me pump will then pump the water through the system as generally outlined above.
As indicated above, the present invention contemplates a particularly preferred panel design for optimum efficiency in a solar heating system as described above. The metal panel or plate of the present invention is desirably fabricated as shown in U.S. Patent 2,609,002. Figure 2 illustrates a single sheet of metal 20 as aluminum or copper or alloys thereof, having applied to a clean surface 21 thereof a pattern of weld inhibiting material 22 corres-ponding to the ultimate desired passageway system. Figure 3 shows the sheet 20 having superimposed thereon a second sheet 23 with a pattern of weld inhibiting material 22 sandwiched between the units. The units 20 and 23 are tacked together as by support welds 24 to prevent relative movement between the sheets as they are subsequently welded together as shown in Figure 4 by passing through a pair of mill rolls 25 to form welded blank 26. It is normally necessary that the sheets 20 and 23 be heated prior to paasing through the mill rollR to assure that they weld to :' .

~065Z19 each other in keeping with techniques well known in the rolling art.
me resultant blank 26 is characterized by the sheets 20 and 23 being welded together except at the area of the weld inhibiting material 22. The blank 26 with the un~oined inner portion corresponding to the p~ttern of weld inhibiting material 22 may then be softened in any appropriate manner as by annealing, and thereafter the blank may be cold rolled to provide a more even thickness and again annealed. The portions of the panel ad~acent the weld inhibicing material 22 are then inflated by the introduction of fluid distending pressure, such as with air or water, in a manner known in the art to form a system of internal tubular passageways 30 corresponding to the pattern of weld inhibiting material as shown in Figure 5. The passageways 30 extend internally within panel 10 and are disposed between spaced apart portions of the thickness of said panel. Thus, panel 10 comprises a hollow sheet metal panel or plate having a system of fluid passageways 30 for a heat exchange medium extending internally therein. If the passageways are i.~ .
inflated by the introduction of fluid distending pressure between flat die platens, the resultant passagewa~rs have a flat topped configuration 31 as shown in Figure 6. If, on the other hand, passageways ~o are formed without the presence of superimposed platens the resultant passageway configuration has a semicircular shape 32 as shown in Figure 7.
As shown in Figure 5, the passageways 30 include opposed headers 33 connected by connecting portions 34 of said passageways extending longitudinally in panel 10 lO~SZl9 between headers 33 and interconnecting same, with the opposed headers 33 extending in a direction transverse to said longitudinal passageways. Preferably, opposed headers 33 are connected by a plurality of spaced3 parallel indivi-dual connecting portions 34 of said passageways extending between the headers. ~`
The passageways include entry portion 35 and exit portion 36 extending from the headers 33 to provide ingress and egress openings for the heat exchange medium. It is a key feature of the present invention that the headers define an angle 37 of at least 91 with respect to the fluid flow and generally with respect to the entry and exit portions 35 and 36, respectively, extending therefrom.
Generally, the angle is from 92 to 100 and preferably 92-1/2to 97-1/2. The provision of angle 37 provides an inclined header which enables uniform fluid distribution within panel 10. Thus, one provides a means to fully drain fluid from the unit and to provide a drain for collected gases thereby preventing air locks. The ensuring of proper drainage for internal fluids overcomes several problems noted heretofore. For example, proper drainage mltigates the possibility of internal solution freezing in the unit with possible subsequent expansion and tube wall fracture.
In addition, proper fluid drainage eliminates the possibil-ity of sediment collecting in the unit which would create an environment conducive to corrosion. Naturally, an efficiently drained unit enables a more efficient system with consequent complete usage of the available solar energy.
An additional significant feature of the panels of : .
:

~065Z'19 the present invention is to provide headers 33 that include bonded portions 38 of the metal 38 which are welded together to provide increased header strength, improve fluid flow -control and directionality and provide interruption in the flow of the heat exchange medium. ~his can be readily obtained in accordance with the present invention by simply not lncluding weld preventive material where one desires the bonded portions 38. As shown in Figure 5, it is preferred to provide waffle-type headers by including a plurality of bonded portions 38 in a generally symmetrical fashion on both headers 33 in order to channel the fluid flow in any predetermined manner. Naturally, non-symmetrical patterns ~ -of bonded portions 38 may be employed and a variety of desired patterns may be selected.
In the preferred embodiment the entry and exit portions 35 and 36 intersect each respective header at the center thereof and are in a line with each other. If desired, however, the entry and exit portions may intersect each respective header at opposite ends thereof as shown by entry and exit portions 35c and 36c in Figure 10. Naturally, also, the entry and exit portions may if desired extend in the same direction as the header as shown in Fi~ure 10 in phantom as 35c' and 36c'. In this case the header angle would be based on the direction of fluid flow, or from the horizontal.
The symmetrical design of the panels of the present invention makes the panels easier to handle so that either end may be the upper portion. Similarly, it can be seen that the angled header promotes drainage in both ends of the panel.

_g_ ` lQ65219 Figures 8, 9 and 10 show variations in the panel design of the present invention. Figure 8 shows a panel lOa wherein the portions o~ headers 33a defining an angle 37a with respect to entry and exit portions 35a and 36a, respec-tively, are scalloped as shown at 40. mis header config-uration enables e~ficient channeling of fluid flow through-out the system. As shown in Figure 8, opposed headers 33a are connected by a plurality of individual spaced, parallel -connecting portions 34a of said passageways extending between the headers. A plurallty of bonded portions 38a are included in headers 33a. Figure 9 shows an alternative -embodiment wherein panel lOb includes a plurality of bonded -portions 38b throughout the panel as well as in headers 33b.
This enables efficient break up of the fluid flow through-out the panel, as well as increased panel strength and flow control and directionality throughout the panel. Panel lOb includes entry and exit portions 35b and 36b, respectively, deflning an angle 37b with respect to headers 33b. Connec-ting portions 34b of the passageways extend between headers 33b. Central bonded portion 39 ~ay be used as a placement guide in the inflation operation.
As shown in Figure 10, entry and exit portions 35c and 36c intersect each respective header 33c at opposite ends thereof and define angle 37c at opposite ends thereof.
As noted above, the panels of the present invention may be prepared in a variety of patterns and shapes to enhance fluid flow and distribution therethrough. Referring now to Figure 11, panel 39 employs headers 40 which are disposed at an angl~ labeled ~ corresponding to an angle ranging from 91 to 100, as disclosed with respect to '' ' : :
, ~O~Zl~

angle 37 in Fi~ure 5. In addition, panel 139 possesses passageways 41 which are likewise disposed at an angle labeled ~-with respect to the longitudinal dimension of the panel as defined by a longitudinal edge thereof, extended in phantom and labeled 42. This angle q is at least 1 with respect to longitudinal edge 42, generally ranges from 2 to 10, and preferably is from 2-1/2 to 7-1/2. The provision of angle in conjunction with angle ~ establishes corresponding inclines in both the headers 40 and the connecting portions 41 which enables panel 139 to provide efficient drainage regardless of the plane in which the panel is mounted. Thus, it can be visualized that the panel may be rotated 90 whereby inlet port 43 and outlet port 44 are relocated to the respective inlet port 43' and outlet port 44' shown in phantom. Thus, panel 139 confers a greater versatility of location as it can be mounted in either a horizontally extended or a vertically extended position while maintaining a desirable level of fluid flow and drainage. Naturally, bonded portions 45 situated in headers 40 confer increased header strength, improved fluid flow and directionality.
Figure 12 illustrates a further modification to the panel of the present invention wherein the panel, labeled 46 is provided with headers 47 which are triangular in shape and are provided with boundary sides 48 which define a part of the outer perimeter of the passageways 49, as well as two of the three borders of the header structure.
~oundary sides 48 are continuous with the fluid ports of panel 46 comprising entry portion 49 and exit portion 50, whereby the longitudinal dimension of at least one of 11~65Z19 respective sides 48 resides in- substantially the same plane as that containing the longitudinal dimension of the respec-tive port. In the illustration of Figure 12, the respective longitudinal dimensions of sides 48 and the entry and exit portions lie in the same longitudinal plane.
The advantage conferred by this arrangement is the availability of the greatestdepth or capacity of header 47 is placed closest to the area of greatestturbulence and flow, that being the locus of entry and exit or heat exchange fluid. Thus, for example~ fluid entering entry portion 49 in Figure 12 encounters the greatest depth of header 47 as defined by vertically extending side 48 as illustrated therein. As panel 46 is generally employed in the upright position wherein the top edge comprises the location of entry portion 49, the primary direction of flow is naturally dictated by gravity to be vertically downward by the most -direct route. Thus, fluid entering at portion 49 tends to travel directly down through vertically ad~acent connecting portions 51, and, as said connecting portions become filled, tends to spill over to laterally displaced parallel connec--ting portions.
Accordingly respecting the above, a further feature resides in the provision of bonded portions 52 which are elongated in shape and which are aligned to define parallel-directed fluid channels 53 integral with said connecting portions and running substantially transverse thereto, which serve to assist in the lateral displacement of heat exchange fluid to respective connecting portions 51. Though the invention has been illustrated with bonded portions 52 comprising oblong or substantially rectangular shapes, it is .. .. . .,,~

to be understood that the invention is not limited thereto, as a wide variety of shapes ma~ be employed which would provlde the parallel channels 53 desired and employed herein.
In accordance with the invention the header may be further modified as above by the provision of bonded por-tions designed to exert a positive influence over the distribution of fluid passing therethrough. Specifically, referring to Figure 13, panel 54, comprising passageways 55 including opposed headers 56 connected by connectlng portions 57 extending therebetween, and entry portion 58 and exit portion 59 extending from the opposite sides there-of 9 is provided with a fluid distribution pattern comprising, in the illustration, bonded portion 60. Though the descrip-tion and accompanying illustration will proceed with refer-ence to a single bonded portion, it is to be understood that the invention is not limited thereby, as patterns are contemplated which, for example, may comprise a plurality of bonded portions and headers of various configurations.
Bonded portion 60 defines at least one point along its perimeter comprising a wedge-shaped pro~ection 61 which assists in the distribution of flow of the heat exchange medium. Projections 61 are respectively located ad~acent and in ~uxtaposition to entry portion 58 and exit portion 59 in Figure 13 as an illustration of one of the features of the invention. The positioning of pro~ection 61 particular-ly with respect to entry portion 58 facilitates the proportionate division of the incoming stream of fluid into two discrete fluid channels. Further, the provision of bonded portion 60 serves to maintain each channel under a 1065Zl9 uniform pressure which overcomes the aforenoted problemof pressure drop. Fluid thus leaving the area of header 56 is permitted to flow evenly and rapidl~v into respective :
connecting portions 57. Likewise, the provision of bonded portion 60 near exit portion 5~ prevents the development of pressure drop as the fluid medium reaches the opposite end of panel 54.
Naturally, further alternative designs may be envisioned by one skilled in the art in accordance with the ;
concepts described above.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A heat exchange panel having a system of internal tubular passageways defining opposed headers connected by connection portions of said passageways extending therebetween, said headers having entry and exit portions extending therefrom to opposed edges of said panel to provide ingress and egress openings for said heat exchange medium, said entry and exit portions having a central axis, wherein said headers include a plurality of interruption portions to provide interruption in the flow of said heat exchange medium and wherein said headers possess outer edges defining the perimeter thereof adjacent the entry or exit portions, respectively, extending therefrom, and wherein the apex of the perimeter of said outer edges defines an external angle of at least 91° with respect to the central axis of said entry and exit portions, respectively, to provide uniform fluid distribution and enable efficient drainage of fluid from the heat exchanger.

2. A metal panel having a desired system of internal tubular passageways for a heat exchange medium disposed between spaced apart portions of the thickness of said panel, said passageways defining opposed headers connected by connection portions of said passageways extending therebetween, wherein said heat exchange medium flows from header to header through said connecting portions, said headers having entry and exit portions extending therefrom to opposed edges of said panel to provide ingress and egress openings for said heat exchange medium, said entry and exit portions having a central axis, wherein said headers include a plurality of portions of said metal which are bonded together to provide interruption in the flow of said heat exchange medium and wherein said headers possess outer edges defining the perimeter thereof adjacent the entry or exit portions, respectively, extending therefrom, and wherein the apex of the perimeter of said outer edges defines an external angle of at least 91° and less than 100°
with respect to the central axis of said entry and exit portions, respectively, to provide uniform fluid distribution and enable efficient drainage of fluid from the heat exchanger, wherein a first plurality of said panels are connected by a common mani-fold communicating with the entry portions of each of said panels for distributing said heat exchange medium into said first plurality of panels and wherein a common collection manifold communicates with the exit portions of each of a second plurality of said panels for collection of said heat exchange medium from each of said second plurality of said panels.

3. A panel according to claim 2, wherein said first plurality of panels and said second plurality of panels are one and the same.

4. A panel according to any one of claims 1, 2 or 3, wherein said opposed headers are connected by a plurality of spaced, parallel individual connecting portions of said passage-ways extending therebetween.

5. A panel according to any one of claims 1, 2 or 3, wherein said headers define an angle of from 92° to 100° with respect to the central axis of the connecting portions.

6. A panel according to any one of claims 1 r 2 or 3, wherein said headers define an angle of from 92-1/2° to 97-1/2°
with respect to the central axis of the connecting portions.

7. A panel according to any one of claims 1, 2 or 3, wherein said passageways include spaced, parallel individual connecting portions of said passageways extending longitudinally in said panel in a direction transverse to and interconnecting said headers.

8. A panel according to any one of claims 1, 2 or 3, wherein said longitudinal passageways include a plurality of portions of said metal which are bonded together to provide interruption in the flow of said heat exchange medium.

9. A panel according to any one of claims 1, 2 or 3, wherein said outer edges are scalloped.

10. A panel according to any one of claims 1, 2 or 3, utilized in a solar heating system.

11. A heat exchange panel for use in a solar energy collector system possessing a system of internal tubular passage-ways defining opposed headers, said headers connected by a plurality of spaced parallel individual connecting portions of said passageways extending therebetween, said headers having entry and exit portions extending therefrom to opposed edges of said panel to provide ingress and egress openings for said heat exchange medium, each of said entry and said exit portions having a central axis, said headers possessing outer boundaries defining the perimeter thereof, said boundaries lying adjacent the apex of said perimeter defining an external angle of at least 91° with respect to the central axis of the most adjacent entry or exit portions, said angle taken in the plane containing said panel, wherein said headers are triangular in shape and possess a plurality of parallel fluid channels communicating with the connecting portions of said passageways and running in a direction substantially transverse thereto wherein said parallel channels are defined by a plurality of aligned bonded portions located within said headers assisting in the distri-bution of said heat exchange medium to the respective connect-ing portions.

12. The panel of claim 11, wherein said headers are displaced with respect to fluid entry and exit portions extend-ing therefrom whereby the respective longitudinal dimensions of said portions and one of the sides defining the outer boundaries of said headers lie in substantially the same plane.

13. The panel of claim 11, wherein said bonded portions are linearly elongated so as to appear substantially rectangular.

14. The panel of claim 12, wherein said boundaries define an angle of from 92° to 100° with respect to the entry and exit portions, respectively, extending therefrom.

15. The panel of claim 14, wherein said boundaries define an angle of from 92-1/2° to 97-1/2° with respect to the central axis of the most adjacent exit or entry portion.

16. The panel of claim 12, wherein said entry and exit portions intersect each respective header in a plane sub-stantially in alignment with a longitudinal edge of said panel.

17. A panel according to any one of claims 1, 2 or 3, wherein said connecting portions of said passageways are of substantially uniform cross-section, and wherein said connect-ing portions are disposed at an angle of at least 1° with respect to said central axis of the connecting portions.