GB2382645A

GB2382645A - Low temperature heating radiator

Info

Publication number: GB2382645A
Application number: GB0128830A
Authority: GB
Inventors: David William Beale
Original assignee: SECO ALUMINIUM Ltd
Current assignee: SECO ALUMINIUM Ltd
Priority date: 2001-12-01
Filing date: 2001-12-01
Publication date: 2003-06-04
Also published as: GB0128830D0

Abstract

A heating radiator 1 comprises a plurality of sections 2 made from extruded aluminium or an aluminium alloy, each section 2 comprising a base 4, a bridge 8 and a front portion 6. The sections 2 are joined along their longitudinal edge to form a base panel 20 which is heated to a high temperature by heating means 12. The front portion 6 is heated by conduction through the bridge 8 and so remains relatively cool. Air flows, by convection, through gaps 24, which may be louvred to exclude dust, between the front portions 6, and through the space between front portion 6 and base 4. When the sections 2 are oriented horizontally the bridge 8, or the base 4 may have perforations 10 to permit air- flow. Insulation 26 may be installed between the base panel 20 and the wall and the exposed surfaces may have a high emissivity coating. A free standing version of the radiator 1 may have identical front portions 6 and bridges 8 on both sides of the base panel 20.

Description

TITLE Low-temperature radiator DESCRIPTION Field of the Invention The invention relates to low-temperature radiators and, in particular, to radiators manufactured by joining two or more extruded aluminium or aluminium alloy sections together to form a radiator comprising a heated base panel and one or more low-temperature radiating surfaces offset from the heated base panel.

Background Art Aluminium is the second most widely used metal after iron. In comparison to other metals, it and its alloys are extremely lightweight, are very resistant to corrosion and exhibit excellent heat conductivity. These specific properties make the base metal or its alloys desirable materials to use in the manufacture of heat transfer or exchange panels. For ease of reference, throughout this Specification the term"aluminium based"refers to pure aluminium or an aluminium alloy.

Most commonly, aluminium based components are produced as extrusions and while the extrusion can be of unlimited length, it will generally have a limited width, typically about 150 to 200 mm. Hence, in order to manufacture a panel the user is required to join a plurality of the extrusions together to achieve the required surface area. Particularly advantageous methods of joining the extrusions together to give a heat panel are discussed in our British Patent Application No. 0114764.4.

In many heating applications, for example in hospitals, there is now a requirement to ensure that the exposed surface area of a radiator is maintained at 43 C or below. Conventional radiators typically operate at temperatures of 80 C or 60 C and to meet the maximum temperature

specification designers generally make the exposed surface of the radiator as a separate steel plate spaced from the heated surface of the radiator by an air gap.

The Applicant perceives distinct cost and efficiency advantages in providing a radiator manufactured from aluminium based extrusions, each extrusion Integrally formed with a heated plate and at least one exposed lowtemperature radiation plate offset from the heated plate.

Summary of the Invention The present invention provides a radiator comprising a plurality of sections extruded from aluminium or an aluminium alloy and a means for heating, wherein each extruded section includes a base portion and a front portion offset from the base portion by an integral bridge portion, the base portions being joined together along their longitudinal edges to form a base panel which in use is heated by the means for heating to a relatively high temperature, the bridge portions constitute a conduction path for heat flow from the base panel to the front portions, the front portions constitute an exposed relatively low temperature radiation surface and a flow path for air current is provided between the base panel and the front portions to extract heat from the base panel, the bridge portions and the front portions by convection.

If the extruded sections are aligned vertically within the radiator then the cavities defined between the base and front portions provide the flow path for the convention air current through the radiator.

Alternatively, if the extruded sections are aligned horizontally within the radiator, then the bridge portions may be perforated to establish the flow path for convection air current.

The extruded sections may have an N, U or H-shaped profile. These shapes are relatively straightforward to extrude using existing technology and meet the criteria for the extruded section.

Preferably, the exposed relatively low temperature radiation surface is coated with a high emissivity coating. This would increase the heat flux radiated from the radiator.

Furthermore, longitudinal edges of neighbounng front portions can be spaced apart to promote air convection into and out of the radiator. Preferably, the longitudinal edges of the front portions are louvred to reduce dust ingression into the cavities defined between the front portions and the back panel.

The invention also provides a double-sided or freestanding radiator further comprising rear portions offset from the base portions by integral bridge portions, the rear portions being identical to the front portions but offset from the base panel in the opposite direction.

Brief Description of the Drawing By way of example only, a preferred embodiment of the present invention will be described in detail with reference to Figure 1 which is a cross-sectional view of a radiator according to the present invention.

Detailed Description of the Preferred Embodiment Fig. 1 illustrates a radiator 1 according to the present invention. The radiator 1 is manufactured from a plurality of sections 2 which are extruded in a conventional manner from aluminium or an aluminium alloy. These sections 2 are generally H-shaped and each has a base portion 4 and a front portion 6 interconnected by an integral bridge portion 8.

Neighbouring sections 2 are joined together along the longitudinal edges of the base portions 4 and then the resultant base panel 20 is mounted with a

traditional means for heating 12 such as hot water pipes or electric elements. As clearly shown in Fig. 1, small gaps 24 are provided between neighbouring front portions 6 and the longitudinal edges of the front portions 6 are louvred to reduce dust collection within the cavities defined between the base panel 20 and the front portions 6. The plurality of front portions 6 functions as a relatively low temperature radiation surface 22.

Although any conventional means such as riveting or welding can be used to join the neighbouring base portions 4 together, we prefer to employ the technique outlined in our British Patent Application No. 0114764.4 whereby a first portion formed along the edge of a base portion 4 is clipped or slid into engagement with a corresponding second portion on the edge of the neighbouring base portion 4 to form a cavity therebetween into which a copper pipe is inserted and expanded radially outwards to positively engage with the first and second portions thereby ensuring that the neighbouring sections 2 are securely locked together. This method is particularly advantageous in that it combines the two steps of joining the neighbouring base portions 4 together and providing the heating means 12 as the expanded copper pipes can be used as a flow path for hot water from an existing heating system.

The uppermost 2a and lowermost 2b extruded sections are slightly different to the intermediate sections 2. The uppermost section 2a is extruded with an integral closure plate 14 which extends to the front and the back of the base portion 4. The forward extension 14a of the closure plate 14 encloses the cavity defined between the base portion 4 and the front portion 6 while the rear extension 14b of the closure plate 14 enables a user to fix the radiator 1 to a wall. The lowermost section 2b has a rear extension 16 similar to the rear extension 14a of the closure plate 14 which again enables the user to fix the radiator 1 to the wall. Furthermore, the lowermost longitudinal edge of the front portion 6 of section 2b is provided with and integral rear projection 18

that encloses the cavity defined between the base portion 4 and the front portion 6.

Prior to fixing the radiator 1 to the wall, a layer of insulation 26 can be placed into the rear cavity defined by the rear extensions 14b and 16 and the base panel 20.

The radiator 1 can be mounted to the wall such that the extruded sections 2 are in horizontal alignment, in which case the cross-section in Fig. 1 is a side view, or alternatively the radiator 1 can be mounted to the wall such that the extruded sections 2 are in vertical alignment, in which case the cross-section in Fig. 1 is a top view.

If the radiator 1 is designed to be mounted in horizontal alignment, then perforations 10 are provided in the bridge portion 8 of each extruded section 2. In use, hot water typically in the range of 60-100 C temperature range, is pumped through the copper pipes 12 at the rear of the base panel 20. Heat from the water is conducted through each of the base portions 4 and each of the bridge portions 8 to the front portions 6 and radiated therefrom. Natural air currents are drawn into the radiator 1 through the gaps 24 between the extruded sections, particularly through those at the bottom. As the air is heated by exposure to the base portions 4, the bridge portions 8 and the front portions 6, it is convected upwards thereby establishing a continual air current through the radiator 1. This air current extracts sufficient heat as it passes alongside the base portions 4 and the front portions 6 and through the perforations 10 in the bridge portions 8 to ensure that the temperature of the front portions never exceeds 43 C, thereby establishing the low temperature radiation surface 22. At the initial design stage, control over the maximum temperature attained in use by the front portions 6 can also be achieved by varying the amount of perforations 10 as a proportion of the total area of the bridge portions 8 which act as the conduction heat path from the base portions 4 to the front portions 6.

Instead of forming the perforations 10 in the bridge portion 8, it is equally feasible that perforations could be punched through the base portion 4 on either side of the bridge portion 8 to perform the same function. In such a design, the control over the conduction heat path from the heat source 12 to the front portions 6 is achieved by placing the heat source 12 on the side of the perforations remote from the integral bridge portion 8, so that as described above the area of the perforations as a proportion of the total area of the base panel 20 limits the conductive heat flow to the front portions 6.

It will be understood that if the radiator is designed for vertical alignment, the perforations 10 are no longer required because the air convention currents will naturally flow upwards through the cavities defined between the front portions 6 and the base panel 20 without being hampered or obstructed by the bridge portions 8.

An obvious modification is the double-sided or freestanding low temperature radiator wherein the extruded sections have not only a base portion and a front portion but also an integral rear portion which is identical to the front portion but offset from the base panel in the opposite direction.

Claims

CLAIMS 1. A radiator comprising a plurality of sections extruded from aluminium or an aluminium alloy and a means for heating, wherein each extruded section includes a base portion and a front portion offset from the base portion by an integral bridge portion, the base portions being joined together along their longitudinal edges to form a base panel which in use is heated by the means for heating to a relatively high temperature, the bridge portions constitute a conduction path for heat flow from the base panel to the front portions, the front portions constitute an exposed relatively low temperature radiation surface and a flow path for air current is provided between the base panel and the front portions to extract heat from the base panel, the bridge portions and the front portions by convection.
2. A radiator according to claim 1, wherein the bridge portion of the extruded sections is perforated.
3. A radiator according to claim 1 or claim 2, wherein the profile of the extruded section is H, U or N-shaped.
4. A radiator according to any preceding claim, wherein the exposed relatively low temperature radiation surface is coated with a high emissivity coating.
5. A radiator according to any preceding claim, wherein longitudinal edges of neighbouring front portions are spaced apart to promote air convection.
6. A radiator according to claim 5, wherein the longitudinal edges of the front portions are louvred to reduce dust ingression between the front portions and the back panel.

<Desc/Clms Page number 8>
7. A radiator according to any preceding claim, wherein in use the

temperature of the exposed relatively low temperature radiation surface is below 43OC.
8. A radiator according to any preceding claim further comprising rear portions offset from the base portions by integral bridge portions, the rear portions being identical to the front portions but offset from the base panel in the opposite direction.
9. A radiator substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.