This invention relates, in a first aspect thereof, to an improved design of radiator fin. In further aspects thereof, the invention relates to a heat exchange coil formed from a plurality of such fins, and to a radiator incorporating such coils.
Fin radiators (sometimes referred to as finned radiators) comprise a heat exchange coil provided with a plurality of fins extending from the heating element and in conductive contact therewith. The purpose of the fins is to increase the surface area of the heat exchange coil and thereby increase the efficiency of heat transfer from the heating element to the surrounding air.
Fin radiators for domestic use typically utilise a metal pipe adapted to deliver heater water from a water heating system through the heat exchange coil. The pipe is generally arranged so as to be horizontal as it passes through the heat exchange coil, with the fins arranged vertically so as to channel air upwards through the heat exchange coil and over and around the pipe. The heat exchange coil is generally housed within a decorative casing which can also serve to direct air flow. Fin radiators of this type have found use in perimeter heating applications, and in particular in low level heating installations on, or in place of, skirting boards or baseboards.
The applicant's own U.S. Pat. No. 5,406,937 describes a baseboard fin radiator having two horizontal pipes for the delivery of heated water, the pipes being arranged in vertical alignment with one another. The advantage of having two pipes is that either: both pipes may be used to deliver heated water to the radiator directly from the water heating system, thereby doubling the heat transfer efficiency; or one pipe may be designated a flow pipe to deliver heated water to the radiator directly from the water heating system, with the other pipe designated a return pipe to return water to the water heating system.
A previously unrecognised drawback of the system disclosed in U.S. Pat. No. 5,406,937 arises from the arrangement of the two pipes in vertical alignment. This results in air drawn up into the underside of the heat exchange coil flowing around the lower pipe, but then being diverted past the sides of the upper pipe. That is to say, the lower pipe effectively blocks the air stream from fully contacting the upper pipe. This occurs because the relatively small height of the radiator—necessitated by its installation as a baseboard heater—means that the separation between the upper and lower pipes is insufficient for the air to flow into the space between the pipes and then around the upper pipe, bearing in mind that the air flow is dictated only by natural convection. As a result of this restricted air flow around the upper pipe, the heat transfer efficiency of the unit is compromised.
The present invention seeks to provide an improved radiator fin, heat exchange coil, and fin radiator which overcome the above discussed drawbacks of the known prior art by enabling an enhanced air flow, thereby to optimise heat transfer efficiency.
According to a first aspect of the present invention there is provided a radiator fin having front and rear faces, and defined by upper and lower edges and opposed side edges, said fin having first and second apertures, each passing through the front and rear faces and adapted to receive and contact a conductive element for the transfer of heat to the fin, wherein the centre of the first aperture is offset relative to the centre of the second aperture, such that said first and second aperture centres are not vertically aligned when the fin is installed.
The construction of the fin with offset apertures serves to enhance heat transfer by ensuring that both conductive elements are fully presented to a stream of air drawn upward over the fin by natural convection, when the fin is installed. This is distinct from the undesirable arrangement of the prior art where the lower conductive element blocks the air stream from fully contacting the upper conductive element.
In order further to optimise the air flow, and hence the heat transfer efficiency, the fin preferably further comprises a plurality of flutes on at least one of the front and rear faces, said flutes being arranged so as to be vertically oriented when the fin is installed. The vertical fluting serves to increase the surface area of the fin, and also to direct air flow to the conductive elements. The provision of fluting on fins to increase surface area is known from the prior art, but such fluting tends to horizontal across the fin, which can be counter-productive for efficient air flow.
Whilst the fin may be of any shape or configuration, it is generally preferred that it be rectangular, with the upper and lower edges being substantially parallel to one another, and the opposed side edges being substantially parallel to one another and substantially perpendicular to the upper and lower edges. In rectangular embodiments of the fin, the flutes are preferably arranged substantially parallel to the opposed side edges.
The lower edge of the fin is preferably formed with a raised central section so as to present an oblique mounting surface adjacent the junction of the lower edge with each side edge, each said mounting surface being adapted to receive a mounting element of a radiator casing. This provides a simple but effective mechanism for removable attaching a radiator casing to the fin.
The conductive elements which the fin apertures are adapted to receive and contact may be of any configuration and may include for example electric heating elements. It is generally preferred however that each said conductive element for transfer of heat to the fin is a pipe connector adapted to enable delivery of heated water, for example from a domestic heating system.
The radiator fin according to the first aspect of the present invention may desirably be combined in an assembly of like fins to form a heat exchange coil suitable for use in a radiator.
Therefore, according to a second aspect of the present invention there is provided a heat exchange coil comprising a plurality of like radiator fins mounted adjacent one another, each said radiator fin having:
and wherein the first aperture of each fin is aligned with the first aperture of each adjacent fin, and the second aperture of each fin is aligned with the second aperture of each adjacent fin, thereby to form first and second conduits extending through the heat exchange coil, each adapted to receive and contact a said conductive element for the transfer of heat to the fins.
The heat exchange coil according to the second aspect of the present invention may comprise a plurality of like radiator fins according to any embodiment of the first aspect of the present invention as hereinbefore described, mounted adjacent one another.
As noted above with reference to the first aspect of the invention, the conductive element for transfer of heat to the fins is preferably a pipe connector adapted to enable delivery of heated water. In such preferred embodiments, the heat exchange coil further comprises a first said pipe connector mounted in the first conduit, and a second said pipe connector mounted in the second conduit, each said pipe connector being adapted for connection to a water heating system thereby to deliver heated water to the heat exchange coil.
Preferably, one of said first and second pipe connectors is adapted for connection to a flow pipe to deliver heated water from the water heating system to the heat exchange coil, and the other of said first and second pipe connectors is adapted for connection to a return pipe to return water from the heat exchange coil to the water heating system. Alternatively, both first and second pipe connectors may be arranged for delivery of heated water to the heat exchange coil directly from the water heating system.
To further improve the heat transfer efficiency, at least one of said first and second pipe connectors may be provided with internal rifling. Alternatively, or additionally, at least one of said first and second pipe connectors may be provided with at least one internal swirler. These optional components serve to promote mixing, and thus temperature equalisation, within the water stream.
In embodiments of heat exchange coil which comprise a plurality of like radiator fins having oblique mounting surfaces as hereinbefore described, the oblique mounting surfaces of each fin are preferably aligned with the oblique mounting surfaces of each adjacent fin, thereby to form elongated oblique mounting surfaces extending along the underside of the heat exchange coil.
The heat exchange coil according to the second aspect of the present invention may desirably be combined with a radiator casing to form a fin radiator suitable for use as a baseboard heater.
Therefore, according to a third aspect of the present invention there is provided a radiator comprising:
The radiator according to the third aspect of the present invention may comprise a heat exchange coil formed from a plurality of like radiator fins according to any embodiment of the first aspect of the present invention as hereinbefore described, mounted adjacent one another.
Independently of the above, the radiator according to the third aspect of the present invention may comprise a heat exchange coil according to any embodiment of the second aspect of the present invention as hereinbefore described.
The radiator casing preferably comprises a back plate adapted to be secured to a wall, and further adapted to engage with the heat exchange coil, and a front panel adapted to engage with the back plate and with the heat exchange coil.
In preferred embodiments of radiator which comprise a heat exchange coil having oblique mounting surfaces as hereinbefore described, each of the back plate and the front panel preferably further comprises a mounting element adapted to engage with a respective oblique mounting surface.
Each of the front panel and the back plate preferably comprises an upper portion extending beyond the upper edge of the heat exchange coil, defined by the upper edges of the plurality of fins, thereby to define an air space above the heat exchange coil. The upper portion of the front panel preferably comprises a grille section located adjacent said air space, thereby to enable heated air to flow from said air space into a room in which the radiator is mounted.
The upper portion of the front panel may preferably be angled relative to the upper edge of the heat exchange coil, towards the back plate. Similarly, the upper portion of the back plate may preferably be angled relative to the upper edge of the heat exchange coil, towards the front panel. In such embodiments, the upper portion of the front panel is preferably adapted to engage with the upper portion of the back plate. This arrangement give rise to a chimney effect caused by the angled upper portion of the back plate directing warmed air in the air space out through the grille in the angled upper portion of the front panel. The angled upper portion of the back plate also serves to project the warmed air forwards and away from a wall on which the radiator is mounted. This helps to alleviate dust marks on walls and further to increase heating efficiency by projecting heat into the room rather than into the wall.
The radiator according to the third aspect of the present invention is preferably adapted to be installed on, or in place of, a skirting board or baseboard, and most preferably is adapted to be installed as a perimeter heating system.
In order that the present invention may be more clearly understood, a preferred embodiment thereof will now be described in detail, though only by way of example, with reference to the accompanying drawings, in which:
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The dimensions for the preferred embodiment of radiator fin 10 shown in
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The alignment of the fins 10 also enables the formation of extended oblique mounting surfaces (not visible in
During use, heated water flows through the pipe connectors 24, 25 and heat is transferred to the fins 10. Warmed air rises up through the heat exchange coil 30 from the lower edges 16 towards the upper edges 15 of each fin 10, driven by natural convection. As it rises, the fluting 19 directs the air flow onto and around each pipe connector 24, 25 to maximise heat transfer efficiency.
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The upper edge 48 of the front panel 42 and the upper edge 49 of the back plate 43 are shaped so as to have a complementary profile to one another such the upper edge 48 of the front panel 42 can clip over the upper edge 49 of the back plate 43 to retain the former in place. In use, the back plate 43 will be secured to a wall using conventional wall fixings (not shown).
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