GB2525203A

GB2525203A - Radiator

Info

Publication number: GB2525203A
Application number: GB1406769.8A
Authority: GB
Inventors: David Russell; Richard Smith; Chris Illman; Craig Nelson; Wil Shoenmakers; Rod Smith; Colin Turner
Original assignee: PA Knowledge Ltd
Current assignee: PA Knowledge Ltd
Priority date: 2014-04-15
Filing date: 2014-04-15
Publication date: 2015-10-21
Also published as: GB201406769D0

Abstract

The radiator (20, figure 2) has walls 40 defining a cavity 42 for holding an atmosphere at a pressure lower than the ambient surroundings. The walls are composed of a plastics material such as polypropylene, polyethylene or some other polymer and have a layer of metallic material, ideally aluminium. Preferably the plastics material includes carbon fillers to increase the thermal conductivity of the plastics. A heat transfer portion (18, figure 2) may be provided that includes an enclosed space (30, figure 3e) to receive an electrical heating element (32, figure 3e) or a water heating element (34, figure 3f). Alternatively a passageway (22, figure 3a) or open side (24, figure 3b) may be provided to receive a hot water pipe (26, figure 3c). Heat provided to the transfer element vaporises a small amount of water at low temperature within the cavity, heating the walls efficiently. A fitting 44 can be provided on the radiator that selectively fluidly communicates the cavity with the ambient surroundings. A vacuum pump (50, figure 7) attached to the fitting can ensure that the cavity is maintained at the required pressure, ideally 0.1 bar. The vacuum pump may receive power from heating of the radiator.

Description

RADIATOR

The present invention relates to a radiator, for example for heating a living space, which may be provided as part of a heating system including a plurality of such radiators or provided as an individual radiator with its own respective heating element.

It is known to provide a heating system with a water boiler, pump and a plurality of radiators, for example having a panel shape. The radiators define cavities through which water may be pumped and are connected, via a series of pipes, to the water boiler and pump. Hot water is pumped from theboiler to each radiator panel, through each radiator panel and returned to the boiler.

Such systems can take a long time for each radiator panel to reach a required temperature, depending upon how many radiators are in the system, because a large amount of hot water needs to be circulated through the system. As the hot water is circulated, heat loss is experienced throughout via connecting pipe work and radiator panels.

WO 2013/070069 considers an alternative type of radiator having a heat exchanger, in the form of a tube, which extends through the cavity of the radiator. Hot water from a water boiler may be pumped through only the hcat exchanger, rather than the entire cavity of the radiator. The cavity of the radiator may contain a medium that evaporates as soon as hot water flows through the heat exchanger so that a smaller volume of water is pumped around the entire system and individual radiators are heated more quickly. That publication proposes a method of manufacturing such aradiator by welding together two opposing plates with the heat exchanger in the cavity between those plates.

It is an object of the present invention to provide a radiator with the appropriate technical functionality, but that can be constructed in a more cost effective manner.

According to the present invention, there is provided a radiator for transferring heat from a heating element to ambient surroundings. The radiator may include walls defining a cavity for holding an atmosphere at a pressure lower than the ambient surroundings. The walls may be composed of a plastics material having a layer of metallic material.

The use of plastics material in the walls of the radiator allow the radiator to be constructed more easily and more cheaply. By providing a layer of metallic material, it becomes possible to retain a lower pressure, such as approximately 0.1 bar, for a period in excess of such as 10 years. In this way, a radiator having practical usability can be constructed.

The walls may be configured to have a gas permeability of no more than 1 x 1 o8 cc/sec.

Such permeability may be achieved by choosing appropriate metallic materials having appropriate thicknesses. It allows an ipitially charged radiator to be sealed and maintain an appropriate low pressure for the required life of that radiator product.

The plastics material may include a layer of metallic material in the form of a multi-layered laminate of plastics material, and metal. The plastics material may include a layer of metallic material in the form of a moulded plastics material with a deposited layer of metal. The plastics material may include a layer of metallic material in the form of a moulded plastics material outer structure containing a semi-rigid or flexible inner liner constructed of a multi-layered material of plastics material and metal.

In this way, the non-permeable metallic material can achieve low levels of gas permeability as required.

The plastics material may at least include a polymer material. Furthermore, the plastics material may at least include one or both of polypropylene and polyethylene.

The metal may at least include aluminium.

The thermal conductivity of aluminium, used as the gas permeable barrier layer, is 200 W/mk. This may act to improve transfer of heat through the radiator.

The walls may include conductive materials as fillers within the make-up of the plastics material. For example, carbon maybe added as a modifying filler to the plastics material, such as polypropylene. This may significantly improve the thermal conductivity of the radiator walls. In particular, although the thermal conductivity of polypropylene is 0.2 W/mk, by adding heat conductive fillers to a polymer in the radiator walls, conductivity of 20 W/mk can be achieved.

The walls and the cavity of the radiator may be heated in different alternative ways.

However, preferably, the radiator includes a transfer portion configured for thermal connection with a hcating element. The heating element may be an external elcment, such as an electric heating element or a pipe carrying hot water.

The transfer portion may include an enclosed space for receiving a heating element within the radiator. In this way, the heating element can be inserted into the enclosed space, for example making contact with the surfaces defining the enclosed space, so as to maximise transfer of heat from the heating element to the radiator. The enclosed space may take the form of a closed passageway having one entrance opening defined in the radiator. Alternatively, the enclosed space may form a passageway through the radiator.

Such a passageway may be suitable for receiving therethrough a pipe as the heating element.

In one embodiment, the radiator itself may include the heating element. For example, it may include a pipe fitted in the enclosed space and configured for connection to a hot water system.

The radiator may thrther include a fitting configured to provide selected fluid connection with the cavity and via which the pressure in the cavity can be reduced.

In this way, a source of vacuum can be connected to the cavity by means of the fitting so as to reduce the pressure in the cavity. The fitting can be used as part of the original manufacture/supply stage. Also, such a filling could be used subsequently for servicing of the radiator.

The fitting may itself include a vacuum pump.

In this way, the cavity of the radiator can conveniently have its pressure lowered at any stage.

The vacuum pump may be configured to receive power from an external source.

For example, it could be electrically or mechanically operated by a user.

Alternatively, the vacuum pump may be configured to receive power from heating of the radiator, for example during the normal operating cycles of the radiator in use.

In one embodiment, the vacuum pump includes a vacuum chamber, a first one way valve providing communication out of the cavity into the vacuum chamber and a second one way valve providing communication out of the vacuum chamber to the ambient surroundings. The vacuum chamber may be configured to increase in volume with heating of the radiator. In this way, the vacuum chamber, when heated and expanded, accommodates atmosphere from the cavity. On the other hand, when the vacuum chamber decreases in volume with cooling of the radiator, it is configured to expel previously accommodated atmosphere to the ambient surroundings through the second one way valve.

In use or as sold, a radiator may be provided holding a pressure between such as plus and minus 10% of 0.1 bar.

Such a radiator may be provided holding a small amount of water in the cavity.

The volume of water depends on panel size, material, internal pressure heat source. When the heating element heats the radiator, the water will be turned to water vapour so as to effectively and efficiently heat the walls of the radiator.

According to the present invention, there is also provided a heating system including a plurality of the radiators as discussed above. These may be positioned at respective intervals along a pipe system carrying heating hot water. Each radiator has a thermal connection with the pipe system.

According to the present invention, there is also provided a method of constructing a radiator as defined above. The method includes forming walls to define a cavity for holding an atmosphere at reduced pressure and constructing the walls from plastics material having a layer of metallic material.

The invention will be more clearly understood from the following description, given by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates a known heating system; Figure 2 illustrates a heating system incorporating radiators according to the present invention; Figures 3(a) to (f) illustrate schematically radiators according to the present invention; Figure 4 illustrates schematically a cavity defined within a radiator embodying the present invention; Figure 5 illustrates an embodiment for the construction of a radiator embodying the present invention; Figure 6 illustrates an alternative construction of a radiator embodying the present invention; Figure 7 illustrates schematically functioning of a vacuum replenishment valve for use with a radiator embodying the present invention; and Figure 8 illustrates schematically mounting of a vacuum replenishment valve to a radiator embodying the present invention.

In known domestic central heating systems, hot water is pumped through the cavities of a series of radiator panels. Such a system is illustrated schematically in Figure 1.

A boiler 2 heats water and a pump 4 pumps that heated water out through a feed pipe 6. The water returns to the boiler 2 via a return pipe 8. A series of radiators 10 are connected between the feed pipe 6 and the return pipe 8. In particular, each radiator 10 defines a cavity through which hot water from the feed pipe 6 flows to the returti pipe 8.

S Figure 2 illustrates schematically an equivalent system incorporating an example of a radiator embodying the present invention. In this system, the distinction between a feed pipe and a return pipe is less clear. A boiler 12 heats water which is pumped by a pump 14 through a pipe 16 back to the boiler 12. Respective transfer portions 18 on each radiator arranged at respective intervals along the pipe 16, transfer heat from the pipe I 6 to the respective radiator 20. Unlike the conventional system of Figure 1, cavities defined within the radiators 20 are sealed and are not in fluid communication (only thermal communication) with the hot water carried by the pipe 16.

It is only necessary that the radiator includes walls defining the cavity. The shape of those walls as part of the overall shape of the radiator can take the form of any known radiator. One such form is a panel radiator of the type illustrated schematically in the figures.

Transfer of heat from a heating element to the walls and cavity of the radiator can be achieved in any of a variety of different ways. The heating element itself or means for receiving the heating element may extend into the cavity. However, the illustrated enibodiments show schematically a transfer portion 18 which is thermally connected to the cavity so as to heat the atmosphere in the cavity. Merely for an ease of understanding, as illustrated, the transfer portion 18 is illustrated at a lower portion of the walls of the radiator 20 defining the cavity.

Figures 3(a) to (f) illustrate schematically examples of possible arrangements for the transfer portion 18.

In the embodiment of Figure 3(a), the transfer portion 18 defines an enclosed space which takes the form of a passageway 22 through the radiator. As illustrated in Figure 2, pipes of a heating system may be inserted through the passageway 22. Preferably, the passageway 22 is close fitting with any pipes so as to achieve good thermal transfer, As illustrated in Figure 3(b), it is also possible for the transfer portion 18 to have an open side 24 for receiving a surface of a pipe. The open side 24 might preferably have a

S

shape corresponding to half of the cross section of a pipe. A separate part may be provided to clamp against the transfer portion 18 so as to hold any pipe in place.

In the embodiment of Figure 3(c), the radiator is itself provided with a pipe 26 installed in the transfer portion 18. The pipe 26 may have fittings 28 on each end allowing it to be fitted in a system as illustrated in Figure 2.

In the alternative arrangement of Figure 3(d), the transfer portion 18 defines an enclosed space 30 which is open only at one end. As illustrated in Figure 3(e) a heating element, such as an electric heating element 32 can be inserted into the enclosed space 30 of the transfer portion 18. Alternatively, Figure 3(1) illustrates schematically a heating element carrying water with feed and return ports at the same end of the heating element 34.

Figure 4 illustrates schematically the walls 40 of the radiator 20 defining the cavity 42 therebetween. The illustrated embodiment also includes a fitting 44 providing selective connection to the atmosphere within the cavity 42. By means of this fitting 44, it becomes possible to reduce the pressure of the atmosphere within the cavity 42 relative to the ambient surroundings. With a reduced pressure, it becomes possible to vaporise a medium, -such as water, within the cavity 42 at a lower temperature, thereby improving the efficiency of transfer of heat to the walls 40 of the radiator 20. Preferably, the panel is sealed so as to maintain a pressure of preferably 0.1 bar for ten years. In some embodiments, it may be possible to seal the radiator during manufacture with a reduced internal pressure such that it is not necessary to provide the fitting 44.

In order to provide a plastics material radiator which can retain a reduced pressure of preferably +-10% of 0.1 bar for a desired period of time, such as ten years, is proposed to include in the plastics material a layer of non-permeable metallic material.

The plastics material may be a polymer.

In one arrangement, a multi-layered laminate material of plastics material (such as polymer) and metal (such as aluminium) can be used for the walls ofthe radiator. In another embodiment, there may be provided a moulded plastics material panel (for instance constructed of a polymer) with a thin deposit layer of metal (such as aluminium).

In yet another arrangement, a moulded plastics material outer structure (for instance of polymer) may be provided containing a semi-rigid or flexible inner liner constructed of' a multi-layered material of plastics material (such as polymer) and metal. (such as aluminium).

It will be appreciated that, while the thermal conductivity of steel, as often used for radiators, is 50 W/mk, the thermal conductivity of plastics materials, such as polypropylene, are more like 0.2 W/mk. According to some embodiments, it is proposed to add heat conductive fillers, to the plastics material. Such fillers can improve the overall conductivity of the structure to 20 W/mk.

In addition, it is noted that the thermal conductivity of aluminium is 200 W/mk. By using this material as the gas permeable barrier layer, it is possible to further improve transfer of heat through the radiator panel.

Figures 5 and 6 illustrate schematically possible layer structures for radiator walls embodying the present invention.

In the structure of Figure 5, the outçr walls are formed from polypropylene with a vacuum metallised aluminium coating to the ipside. The vacuum metallising can be achieved through an evacuation hole after welding. The hole can be suitably plugged and sealed as part of the evacuation process.

With such a structure, a complete envelope of the aluminium layer provides a barrier with a permeability in excess of 1 x io cc/sec. With such a low permeability, appropriate low pressures can be maintained for long periods of time, such as ten years.

According to the structure of Figure 6, an outer layer of polypropylene is provided for strength, a middle layer of aluminium foil is provided for low permeability and an iimer layer of polyethylene is provided to enable effective welding between the two opposing walls. With this structure, there is still a joint where the two polymer (polyethylene) faces are welded. This may allow an overall increased permeability for the radiator such that periodic servicing to reduce the internal pressure may be necessary.

A fitting 44 such as described with reference to Figure 4 could be provided allowing an external vaôuum pump to be connected to the radiator. However, it is alternatively possible to incorporate a vacuum pump into the fitting itself Ihe vacuum pump may be powered from an external source, for example a mechanical or electrical source. Alternatively, it is possible to provide a vacuum pump which is powered by means of the operating cycle of the systcm itself Figure 7 illustrates schematically a vacuum replenishment valve for use with a radiator.

The valve 50 includes a first one way valve 52, a vacuum chamber 54 and a second one way valve 56. When the radiator 20 is heated and the valve so increases in S temperature, the housing of the vacuum chamber 54 expands as illustrated by dashed lines in Figure 7. The first one way valve 52 allows atmosphere to be drawn from the cavity of the radiator panel 20 into the volume of the vacuum chamber 54. Upon cooling, the volume of the vacuum chamber 54 reduces again, for example by means of a spring return.

The first one way valve 52 prevents the gas within the vacuum chamber 54 returning to the cavity of the radiator 20, but the second one way valve 56 allows this gas to be discharged to the ambient surrounding atmosphere. In this way, as a radiator is cycled between hot and ambient temperatures and a valve similarly cycles between hot and ambient temperatures, the valve automatically maintains a reduced pressure within the cavity of the radiator 20.

The vacuum replenishment valve 50 may be mounted externally of the radiator or contained within the cavity of the radiator. These two alternatives are illustrated schematically in Figure 8. Mounting should be such that any additional leakage paths are limited to that of the exhaust port only.

Claims

Claims 1 A radiator for transferring heat from a heating element to ambient surroundings, the radiator including: walls defming a cavity for holding an atmosphere at a pressure lower than the ambient surroundings; wherein: the walls are composed of a plastics material having a layer of metallic material.
2 A radiator according to claim I wherein the walls are configured to have a gas permeability of no more than 1 x io8 cc/sec.
3 A radiator according to claim 1 or 2 wherein the plastics material includes a layer of metallic material constructed as at least one of: a multilayered laminate of plastics material and metal; a moulded plastics material with a deposited layer of metal; and a plastics material outer structure containing a semi-rigid or flexible iimer liner composed of a multilayered material of plastics material and metal.
4 A radiator according to claim 1, 2 or 3 wherein the plastics material at least includes a polymer material.
A radiator according to any preceding claim wherein the plastics material at least includes one or both of polypropylene and polyethylene.
6 A radiator according to any preceding claim wherein the metal at least includes aluminium.
7 A radiator according to any preceding claim wherein the walls include conductive materials as fillers within the makeup of the plastics material.
8 A radiator according to claim 7 wherein the fillers include carbon.
9 A radiator according to any preceding claim further including a transfer portion configured for thermal connection with a heating element.
A radiator according to claim 9 wherein the transfer portion includes an enclosed space for receiving a heating element within the radiator.
11 A radiator according to claim 10 wherein the enclosed space forms a passageway through the radiator for receiving therethrough a pipe as the heating element.
12 A radiator according to claims 10 or 11 further including a pipe fitted in the enclosed space as the heating element and configured for connection to a hot water system.
13 A radiator according to any preceding claim further including a fitting configured to provide selective fluid connection with the cavity and via which the pressure in the cavity can be reduced.
14 A radiator according to claim 13 wherein the fitting includes a vacuum pump.
1 5 A radiator according to claim 14 wherein the vacuum pump is configured to receive power from an external source.
16 A radiator according to claim 14 wherein the vacuum pump is configured to receive power from heating of the radiator.
17 A radiator according to claim 16 wherein the vacuum pump includes a vacuum chamber, a first one way valvc providing communication out of the cavity into the vacuum chamber and a second one way valve providing communication out of the vacuum chamber to the ambient surroundings, wherein the vacuum chamber is configured to increase in volume with heating of the radiator so as to accommodate atmosphere from the cavity and then decrease in volume with cooling of the radiator so as to expel previously accommodated atmosphere to the ambient surroundings.
18 A radiator according to any preceding claim holding a pressure between plus and minus 10% of 0.1 bar.
19 A radiator according to claim 14 holding a small amount of water.
A heating system including a plurality of radiators as defined in any one of claims 1 to 19 to be positioned at respective intervals along and for thermal connection with a pipe system carrying heating hot water.
21 A method of constructing a radiator according to any one of claims ito 19, the method including: forming walls to define a cavity for holding an atmosphere at a pressure lower than ambient surroundings; and constructing the walls of a plastics material having a layer of metallic material.
22 A radiator constructed and arranged substantially as hereinbefore described with reference to and as illustrated by Figures 2 to 8 of the accompanying drawings.
23 A heating system constructed and arranged substantially as hereinbefore described with reference to and as illustrated by Figures 2 to 8 of the accompanying drawings.
24 A method of constructing a radiator substantially as hereinbefore described with reference to and as illustrated by Figures 2 to 8 of the accompanying drawings.