EP0044365A1

EP0044365A1 - Radiators for use in hot water central heating systems

Info

Publication number: EP0044365A1
Application number: EP80302487A
Authority: EP
Inventors: Victor John Simpson
Original assignee: Alcan Aluminum Ltd; SIMEC Lochaber Hydropower 2 Ltd
Current assignee: SIMEC Lochaber Hydropower 2 Ltd
Priority date: 1980-07-22
Filing date: 1980-07-22
Publication date: 1982-01-27

Abstract

A radiator (10) for use in hot water central heating systems is constructed from extruded aluminium alloy sections. One section having a tubular duct (12) extending therethrough and provided with fins (21) is used as the heat exchanger (11) which interconnects the flow header (24) and return header. These headers (24) each incorporate locking flanges (30. 32) which interlock with respective external slots (23) pre-formed in the fins (21) on each side of the heat exchanger (11). Pressure tight fluid connections between the headers (24) and the duct (12) in each heat-exchanger section are made by double-ended chamfered barrel nipples (34).

Description

This invention relates to the construction and manufacture of radiators for use in hot water central heating systems. A radiator construction is known from UK Specification No. 1 406 108 in which one configuration of section having a tubular duct extending therethrough is used as the heat exchanger and interconnects other configurations of section which form the flow and return headers; the heat exchanger sections have at each end internal slots in which pairs of wedges are driven to hold the headers in position. Although the system of construction allows radiators of any desired length or height to be produced from a common extrusion die thus eliminating the need for moulds or dies for each height of radiator, the construction necessitates the formation of a recess in each end of the heat exchanger sections to accommodate the flow and return headers respectively, and the formation of slots in the walls of the recesses to receive the wedges; these, moreover constitute separate elements that can be lost or come undone.
According to the present invention slots are pre-formed externally in the side of each heat exchanger section and the headers are held in place by locking flanges which engage in the pre-formed slots.
The main feature of this invention is thus the method by which two configurations of section extruded from aluminium or aluminium alloy are interlocked, a desired number of heat exchanger sections being located to link together the flow and return headers to complete an integral water circuit.
The heat exchanger section is so arranged to take full advantage of the differing thermal characteristics between the water to heat exchanger heat transfer coefficient and the air to heat exchanger film coefficient. The construction allows for this to be achieved by arranging longitudinal fins running parallel to the waterway through the heat exchanger. The fins are formed simultaneously with the water tube in the heat exchanger. In a preferred arrangement the surface area of the air-heating surface may be twenty times greater than the surface area inside the tube through which the water passes. Since the longitudinal fins are formed in the same metal as the water tube there is no mechanical or other bond to form a barrier to conducted heat flow within the structure of the heat exchanger. Unlike a conventional panel hot water radiator or cast iron or cast aluminium radiator where the internal surface area in contact with the heating fluid is roughly proportional to the external surface in contact with the air, which latter surface area determines the quantity of heat emission, in the case of this invention both sides of the metal forming the heat exchanger constructed around the fluid path are exposed to dissipate heat to the air. It therefore follows that for a given thickness or weight of material the utilization of both sides greatly reduces the overall weight of basic material required in the heat exchanger to achieve the same unit of heat emission; in fact the heat output of a radiator according to the present invention is over three times that of a flat panel radiator of the same dimensions.
The fluid or water headers are constructed from an aluminium or alluminium alloy extrusion in the same manner as the heat exchanger section. The header sections consist of a tubular core from which extends the capping profile, the edges of which have a longitudinal lip running parallel to the central tube. The ends of the header may conveniently be internally screwed to form a pipe connection. The internal face of the tubular header is thickened in section to conveniently abut against the end of the heat exchanger profile. A pressure tight connection between the waterway in the header and the waterway in the heat exchanger is achieved by the use of multiple chamfered barrel nipples one end of which presses as an interference fit into the tube formed in the heat exchanger section whilst the other end of the barrel nipple is pressed into suitable holes bored into the header section at right angles to the header tube. The holes bored into the header tube are also an interference fit to the chamfered nipples.
Any desired number of heat exchanger sections of any desired equal length may thus be laid side by side and headers of suitable length placed so that the chamfered barrel nipples engage both the holes bored in the header and the tube formed in the heat exchanger section. The headers may then be pressed together until the nipples are fully engaged and the inner face of the header is in abutment with the end of the heat exchanger profile.
In order that the assembled sections should be retained in the assembled position a slot may be cut across the fins of the heat exchanger section adjacent to each end of the section. This slot may be on either or both sides of the heat exchanger section. It may be formed simultaneously with the operation where the heat exchanger section is cut to required lengths. It now follows that the taper lip on the edge of the capping profile which is an integral part of the header previously described is adjacent to the slots formed into the ends of the heat exchanger section. The lip is then pressed into the slots which are intersected at right angles. The lip thus forms a detent in the slots in the ends of the heat exchanger sections thus permanently locking the assembly together in such a manner that the load of any hydrostatic pressure within the waterway is carried by the detent engaged in the slots of the heat exchanger section. This feature removes any axial load acting on the taper nipples.
Assembly as described can be carried out at high speed with the minimum of skill.
An embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which:-

Figure 1 is a partial transverse vertical section through a hot-water radiator constructed in accordance with the invention, Figure 2 is a partial side elevation of the radiator of Fig.1, and
Figure 3 is a section on the line III-III of Fig.2.

As shown in the drawings a hot water radiator 10 constructed in accordance with the invention comprises a series of heat-exchange panels 11 extruded from aluminium and having a central circular waterway 12 from diametrically opposed sides of which extend two webs; the web 13 having a root portion 14 which is thicker than an outer portion 15 and terminating in an off-set extremity 16 and the other web 17 having corresponding portions 18 and 19 but terminating in a plain extremity 20 which is slightly shorter than the extremity 16.
From each side of each of the webs 13 and 17 project three identical fins 21 which each terminate in a transverse flange 22. A slot 23 is formed near each end of each flange 22 and of each fin 21 to define a channel running parallel to the end faces of the panels 11.
The heat-exchange panels 11 are capped at each end by identical headers, only the upper header 24 being shown in the drawings. As shown in Fig.1, the header 24 comprises a generally circular core 25 having a thickened base portion 26 with a flat face 27 which is drilled at intervals to form a series of holes, one of which, indicated by the reference 28, is shown in Fig.1. The upper outer surface of the wall of the core 25 is formed with a series of decorative serrations 29 and from the core 25, at a point near one end of the serrated portion, there extends a capping flange 30 terminating in a tapered internal lip 31. A similar flange 32 extends from near the other end of the serrated portion and terminates in a lip 33, the flanges 30 and 32 together having generally an outwardly divergent channel section within which lies the core 25, the distance between the lips being, before assembly, slightly less than the thickness of the panels 11.
A chamfered barrel nipple 34 is inserted in an interference fit into each end of each waterway 12.
To form the radiator 10 as many panels 11 of any desired length and as are necessary to form the desired width are laid side by side so that the flange 16 of one panel 11 overlies the terminal portion 20 of an adjacent panel 11. The slots 23 may be formed at the same time as the panels 11 are cut to length.
Two corresponding lengths of header extrusion are then cut to form the upper header 24 and the lower header, the core 25 of each header being tapped at each end to receive conventional flow and return connections, plugs or bleeder valves. "Loctite" (Registered Trade Mark) or similar jointing compound is then applied to the exposed portions of the chamfered nipples 34 and a header placed against each end of the juxtaposed panels 11, with the nipples 34 being received in the holes 28, the previously-mentioned intervals between which correspond to the intervals between the nipples 34 projecting from the assembled panels 11.
The headers are then pressed together so that the nipples 34 are fully received, also in an interference fit, in the holes 28 and then the flanges 30 and 32 are clamped together so that the lips 31 and 33 are received in the respective channels defined by the slots 23. The consequent detent formed by the engagement of the flat inner face of the lips 31 and 32 with the outer side wall of the respective slots 23 ensures that the headers are positively interlocked and strongly resist any force tending to prise them away from the panels 11 and any axial load on the nipples 34 is relieved.
The above described construction allows a radiator of high thermal efficiency to be formed of aluminium extrusions which have a characteristic of requiring only about half the weight of metal required for a die cast aluminium radiator of the same heat output or approximately one fifth the weight of a conventional steel panel radiator of the same heat emission. The resultant reduction in material required for a given heat minimum results in considerable cost advantage.
Each panel 11 could if desired have two or more waterways each pair being joined by an integral web.

Claims

1. A radiator (10) for use in hot water central heating systems and constructed from sections, one configuration of section having a tubular duct (12) extending therethrough being used as the heat exchanger (11) which interconnects other configurations of section which form the fluid flow and return headers (24), the heat-exchanger sections (11) having internal slots with which an engagement member co-operates to hold the headers (24) in position,
characterised in
that the sections (11, 24) are extruded from aluminium or aluminium alloy, that the slots (23) are pre-formed externally in the side of each heat excahnger section (11) and that the engagement member is a locking flange (30) which interlocks with the pre-formed external slots (23).

2. A radiator as claimed in Claim 1, in which the flow and return headers (24) each incorporate two locking flanges (30, 32) which interlock with respective slots (23) pre-formed in opposite sides of the heat-exchanger (11).

3. A radiator as claimed in Claim 1 or 2, in which the slots (23) are pre-formed at the ends of fins (21) which are provided on at least one side of the heat-exchanger (11), the slots (23) being engaged by an end portion (31, 33) of a respective flange (30, 32).

4. A radiator as claimed in Claim 3, in which said end portion is an internal lip (31, 33) which is arranged for positive engagement with a wall of the slot (23) to resist any force urging the header (24) away from the heat-exchanger (11).

5. A radiator as claimed in any preceding claim, in which the flow and return headers (24) are drilled at intervals to coincide with the position of the tubular duct (12) or ducts in each heat-exchanger section (11) and in which in respect of the or each said duct (12), one end of a double-ended chamfered barrel nipple (34) is engaged with and pressed into the end of said duct (12) and the other end of the chamfered nipple (34) is pressed into the corresponding hole (28) drilled into the header (24) at right angles to the cored flow path, thus forming a fluid pressure tight connection at each joint between the heat-exchanger duct (12) and the header (24).

6. A radiator as claimed. in any preceding claim, in which a face of each header (24) abuts the corresponding end face of the heat-exchanger (11).