WO1988006260A1

WO1988006260A1 - Convector/radiator construction

Info

Publication number: WO1988006260A1
Application number: PCT/AU1988/000043
Authority: WO
Inventors: Giovanni Giorgilli; Paul Thomas Williams
Original assignee: Hydrotherm Australia Pty. Ltd.
Priority date: 1987-02-17
Filing date: 1988-02-17
Publication date: 1988-08-25
Also published as: AU594234B2; AU1344688A

Abstract

A radiator is constructed of a plurality of fluid transfer members (19) interconnecting opposed headers (17) (18) to form a grid through which heat exchange fluid is circulated. Heat-exchange elements (23) are mounted on each transfer member (19) in heat-exchange contact therewith so that heat in the fluid is conducted to the elements (23). The elements are formed with fins (29) to transfer the heat to ambient air by convection.

Description

CONVECTOR/RADIATOR CONSTRUCTION BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to a convector/radiato construction and relates particularly to such a devic used for heating in buildings and the like utilizing ho water, steam or other heated fluid.

Such devices are commonly known by the nam "radiator" and for the purposes of this specification this term will be used throughout to refer to a convecto radiator which is a heat exchanger which conveys hea from a heated fluid passing therethrough to the surround by both convection and radiation.

Hot water and steam radiators have been commonl used in central heating systems to transfer heat fro water or steam to the surrounds of a building, domesti dwelling or the like. Early radiators were of cast iro or other similar construction while, in recent times, the radiators have been formed of pressed steel panel welded together. The radiators are located as desire and are connected together and to a water or steam boile by means of appropriate piping, usually small bore copper tubing, so that the heated water or steam flows in a circuit from the boiler through each successive radiator and back to the boiler for reheating.

In such a central heating system, the system must allow for the expansion of the water as it is heated. In an open system, extra water volume may be accommodated in an expansion tank. In a sealed system, the increased volume, may be taken up by compressed air in a closed expansion vessel. 2. Background of the Invention

Cast iron and steel radiators are relatively heavy, are costly to manufacture and difficult to fabricate and are relatively difficult to construct so as to be efficient convectors. Further, the relatively large mass involved is slow to heat due to the thickness of the materials and the relatively low thermal conductivity. Further, and importantly, such radiators are subject to corrosion which can seriously inhibit the operation thereof and which may also give rise to potentially dangerous failures.

It has been proposed to construct radiators of other materials, such as copper, aluminium and alloys.

However, copper is far too expensive to be considered for a complete radiator structure other than for very special installations where cost is relatively unimportant.

Aluminium is capable of transmitting more heat per unit area than is steel and is also much lighter. Not unexpectedly, then, aluminium radiators are now becoming more common. Aluminium is not, however, without its problems since an effective means of welding aluminium parts is still being developed while casting aluminium for radiator panels requires a large number of molds or dies for each different size of radiator.

Where aluminium parts are fabricated and sealingly connected, the tolerances of the parts must be relatively close and the seals are always subject to failure. Australian Patent Application No. 24203/77 in the name of Alois Schwarz discloses one construction of radiator utilizing aluminium and in which several aluminium parts are assembled together to form a radiator structure. With the arrangement disclosed in this specification, the various parts require appropriate tolerances to enable a close interengagement and seals are also necessa.ry between those parts conveying fluid.

If individual radiators are manufactured of aluminium as a unit by pressure casting, it is necessary to connect the elements near their upper and lower ends. In such a design four connecting points exist for each radiator.^" However, this method of manufacture is dis¬ advantageous inasmuch as a separate casting die is required for each size of radiator. Thus, the manufacture of radiators of different sizes is very expensive. A further disadvantage of such radiators is that the elements • in order to be able to be withdrawn from the dies, must be somewhat tapered which, particularly in the case of large

radiators, leads to an undesirable shape of the elements. Further, the elements are open on one side and must subsequently be closed in a suitable manner.

It has been suggested that the central parts of radiator elements be made from extruded profiles with separately extruded head pieces which form upper and lower manifolds or headers. With this arrangement, radiators having various heights can be produced with similar head pieces simply by selecting various lengths of the centre pieces. Of course, in such cases, it is not only necessary to connect the elements with one another, but also the head pieces must be connected in a sealing manner with the centre parts of the elements. Thus, each element of the radiator has a number of connecting points which must be sealed, thus adding to the complexity and cost of manufacture..

It •is therefore desirable to provide an improved radiator construction which minimizes the aforementioned disadvantages of prior radiator constructions. It is also desirable to provide an improved radiator construction which utilizes aluminium but which avoids the difficulties associated with interconnecting or joining aluminium parts.

It is also desirable to provide an improved radiator construction whereby a radiator may be of any desired size but which utilizes standard sized aluminium parts.

It is desirable to provide a method of constructing radiators in a* large range of sizes - without requiring vast, expensive capital investment.

It is further desirable to provide a method of constructing radiators whereby changes in design details, such as appearance, can be accommodated regularly with only minor changes in tooling and/or method of fabrication. It is also desirable to provide a method of constructing and assembling an improved radiator utilizing parts extruded of aluminium. SUMMARY OF THE INVENTION

According to the present invention there is provided a radiator having opposed headers interconnected by a plurality of fluid transfer members characterized in that the transfer members are surrounded by separate, heat-exchange elements in contact with the transfer members and adapted to be heated by conduction from the fluid transfer members.

The fluid transfer members preferably comprise a plurality of substantially parallel, spaced tube members interconnected at their opposite ends to the opposed headers to form a grid. Generally, the tube members will extend substantially vertically with the upper and lower headers being substantially horizontal in the operative position. The grid may be formed of any suitable material, preferably resistant to corrosion by the fluid which is to be circulated therethrough. A most suitable material is copper, although any other metal or synthetic plastic material may be used in the construction of the grid. The respective cross-sectional dimensions of the headers and tube members are chosen such that a substantially constant head appears at the top of the tube members and a minimal pressure drop occurs across the grid from an inlet connection to one of the headers to an outlet connection on the opposed header. The headers and tube members may be interconnected by appropriate welding, brazing, mechanical jointing or any other suitable, fluid- tight connecting arrangement.

The heat exchange elements which substantially surround the fluid transfer members, and, preferably, the opposed headers, are preferably formed of aluminium or other^"material with a relatively high thermal conduct¬ ivity. Aluminium is particularly preferred as the elements may be formed as an extrusion and cut to length to suit the particular dimensions of a radiator grid.

The heat exchange elements in the preferred form are provided with heat exchange fins which, in use, conduct heat from the transfer members to the air surrounding the elements whereby the air is heated by convection. In a particular form, the fins extend radially outwardly rom a central hollow core section which engages with the transfer members. Heat exchange elements may also be provided for the headers, such elements preferably inter¬ connecting with the elements on the transfer members to form a substantially unitary structure.

The invention contemplates that the heat exchange element surrounding each transfer member is formed in at least two parts and is engaged with the respective transfer member, the parts being secured together by appropriate interlocking shoulders, clips, fasteners or the like. However, the invention also contemplates a construction where a one piece heat exchange element is formed with a hollow section to receive a tube member, the tube members being inserted into the hollow section and subsequently connected with the headers. BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention will be more readily understood, embodiments thereof will now be described with reference to the accompanying drawings. In the drawings:

Figure 1 is an exploded view of parts of a radiator construction in accordance with the present invention, Figure 2 is an elevational view of a grid core for a radiator construction of the invention,

Figure 3 is a sectional plan view of a part of a radiator construction in accordance with Figure 1 , and

Figure 4 is a view similar to Figure 3 but illustrating a second embodiment of radiator construction. DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, the radiator construc¬ tion illustrated in Figures 1 to 3 is designed for a warm or hot water central heating system in which water is circulated through the radiator to effect transfer of heat from the water to the ambient air and surrounds. The radiator construction includes, a grid 12 formed of copper tubing 12 through which the water circulates via inlet and outlet connections 16 and 14, respectively. The grid 12 forms a core of the radiator construction and includes an upper header 17, a lower header 18 and a plurality of fluid transfer members 19 interconnecting the upper and lower headers 17 and 18. In a preferred construction technique, the fluid transfer members 19 are brazed to the upper and lower headers 17, 18 in a fluid tight manner. Such brazing techniques are well known, are simple to perform and may be carried out either manually or automatically by machine. Thus, the grid 12 is relatively easy to fabricate from readily available copper tube materials.

The cross-sectional dimension of the headers 17 and 18 is generally greater than that of the fluid transfer members 19 so as to provide a relatively even flow of fluid through the grid 12.

In addition to the inlet and outlet connections 14 and 16, the headers 17 and 18 are provided at the ends opposite the inlet and outlet connections 14 and 16 with either a closure plug 21 or a bleeder valve 22, in a known manner.

In accordance with the invention, the fluid transfer members 19 of the grid 12 are surrounded by separate heat exchange elements 23 which are in heat exchange contact with the outer surface of the respective member 19. In the embodiment illustrated, the heat exchange element 23 is formed of two, co-acting parts 23a and 23b which are of identical cross-sectional shape, as particularly shown in Figure 3. The element parts 23a and 23b are of extruded aluminium section cut to the appropriate lengths to suit the dimensions of the grid 12. Each^" element part has a central section 24 with a semicircular-shaped channel 26 which is adapted to engage with a fluid transfer member 19. The central section 24 is formed with interacting clip formations 27 and 28 which enable two parts 23a and 23b to be clipped together around the transfer member 19. \A plurality of heat transfer fins 29 extend from the central section 24 to

dissipate heat from the transfer members 19 to the ambient air.

As shown in Figure 1 , the upper ends of the heat exchange elements 23 are preferably cut away so as to fit around the upper header 17. A top cover member 31 engages across the tops of the heat exchange elements 23 on the grid 12, the top cover 31 having openings 32 to permit movement of convected air therethrough. Inwardly turned legs 33 snap fit into grooves 34 cut into the front and rear edges of the heat exchange elements to retain the top cover in position and lock the elements in place.

Similarly, an end cover 36 clips to an end pair of heat exchange elements 23 to finish the end of the radiator construction. The end cover 36 will be formed with appropriate openings 37 through which the inlet and outlet connections 14 and 16, and any bleeder valve 22, may project.

Figure 4 illustrates a modified form of heat exchange element 38 having a different arrangement of fins 29 and a different construction of the clip forma¬ tions. It will be appreciated that the heat exchange elements may be constructed in a variety of configurations to surround the fluid transfer members 19 in a heat exchange relation. In this regard, it is envisaged that he heat exchange elements 23 will be a snug fit around the fluid transfer members 19 although a conventional heat transfer paste may be used between the surfaces of the transfer members 9 and the heat exchange elements 23. Further, the elements may be connected together by spring , clips or other fastening devices in addition to or instead of integral clip formations.

As is known in the art, the supply and return connections for the heat exchange fluid may be made at any suitable location on the grid 12. Further, the radiator construction of the present invention may be provided with a decorative or protective covering of sheet steel or the like if desirable or. necessary in view of the intended location of the radiator. The covering member may be secured to the radiator itself or to an adjacent support.

It will be appreciated that the structure of the invention facilitates a relatively simple and economical construction of radiator utilizing a single aluminium extrusion in conjunction with the grid of copper tube or the like. By using such a single extrusion, which may be cut to appropriate lengths for radiators of different sizes, the cost of production of manufacturing dies for different radiator dimensions is avoided. Further, a damaged heat exchange element may be easily replaced without substantial dismantling of the radiator structure, and the construction of the invention, while utilizing the advantages of aluminium, and particularly its thermal conductivity, light weight, low thermal capacitance and ease of extrusion, avoids difficulties otherwise associated with the use of aluminium including the difficulty of welding or otherwise providing fluid- tight joints in aluminium parts. The use of copper in forming the core grid is also particularly advantageous as copper has a high thermal conductivity and a high corrosion resistance which, together with relatively high mechanical strength, allows high static fluid pressures in a heating system. However, the core may be formed of any other material such as aluminium or alloys thereof. While particular embodiments of the invention have been shown and described, it will be understood that the invention is not limited thereto, since many modifica¬ tions may be made and will become apparent to those skilled in the.art.

Claims

rClaims .

1. A radiator having a plurality of fluid transfer members interconnected by fluid distribution passageways characterized in that the transfer members are substan¬ tially surrounded by heat-exchange elements in heat- exchange contact therewith to be heated by conduction from the fluid transfer members.

2. A radiator according to claim 1 characterized in that each heat-exchange element is in two parts which interengage with each other to contact and surround the transfer members.

3. A radiator according to claim 2 wherein the two parts are identical and are provided with longitudinal interlocking rib formations which lock the parts together.

4. A radiator according to claim 2 wherein the two parts are complementary with one part having longitudinal locking grooves and the other part having cooperating ribs to snap-engage in the grooves to lock the parts together.

5. A radiator according to any one of claims 1 to

4 wherein said transfer members are tubes of circular cross-section and separate heat-exchange elements are mounted on each transfer member.

6. A radiator according to any one of claims 1 to

5 wherein the fluid distribution passageways comprise opposed headers communicating with each transfer member to form a grid.

7. A radiator according to claim 6 wherein the headers have fluid supply connections and fluid return connections for supply and return of heat-exchange fluid to the radiator.

8. A^' radiator according to claim 6 or claim 7 wherein the grid is formed of copper tubing with the header tubes being of greater cross-sectional dimension than the transfer members, and the heat-exchange elements are formed of extruded aluminium section.

9. A radiator according to any one of claims 1 to 8 wherein each heat exchange element is formed with a plurality of integral fins extending longitudinally of the element to assist heat exchange between the element and ambient air.

10. A radiator according to claim 9 wherein the fins comprise front and rear surfaces of the radiator, and separate top and end caps clip to the fins.

11. A radiator according to any one of claims 1 to 10 wherein a heat transfer paste is infused between the surfaces of the heat transfer members and the heat exchange elements.

12. A radiator substantially as hereinbefore described with reference to the accompanying drawings.