EP1552226B1

EP1552226B1 - Improvements in and relating to heaters

Info

Publication number: EP1552226B1
Application number: EP03763967A
Authority: EP
Inventors: Leo Lamb
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-07-13
Filing date: 2003-07-04
Publication date: 2007-02-14
Anticipated expiration: 2023-07-04
Also published as: DE60311854T2; WO2004008040A1; AU2003251157A1; DE60311854D1; ATE354066T1; EP1552226A1

Abstract

A heater (2) comprises a sealed enclosure (4) containing a heating element (8) and a heat transfer fluid (6) wherein the heating element is surrounded by a confined transfer medium (10).

Description

The present invention relates to an improved heater and to a method of manufacturing the same.
A wide range of heaters exist that use different types of heat transfer media as their source of heat. Heaters that include an electrical heating element as their heat source are commonplace. Generally, the heating element is screwed into a boss at one side of the heater and extends into a compartment that contains oil for transferring heat through the heater. Alternatively, the compartment may be partially evacuated and contain a small amount of working fluid, such as water, whereby the working fluid is heated by means of the heat that is transferred from the heating element. The working fluid is always in its liquid phase around the heating element but turns to vapour further up the compartment as it is heated. However, rapid heating of the fluid by the heating element can cause kettling to occur in the system. Kettling is undesirable because it is extremely noisy.
EP 0 668 479 (British Gas plc) describes a themosyphon radiator having a hot water pipe that may be surrounded by a covering. GB 2 099 980 (Ssurrah) describes a hot water pipe surrounded by a metal gauze wick. GB 695628 (Richings) discloses a method for manufacturing a heater by attaching a first part of an enclosure unit to a second part to form a sealed enclosure around a heat transfer medium.
It is an aim of the present invention to provide an improved heater that retards kettling.
A further aim of the present invention is to provide a method of manufacturing an improved heater that retards kettling.
Accordingly, a first aspect of the present invention provides a heater comprising a partially evacuated sealed enclosure containing a working fluid and an electrical heating element, characterised in that the electrical heating element is surrounded by a porous or perforated heat exchange material contained within a compartment, said working fluid being provided in an amount such that in normal use the heating element and heat exchange material are always immersed in the liquid phase of the working fluid.
The heat exchange material increases the area of heat transfer from the element to the fluid thereby retarding kettling. The heat exchange material should have pores or perforations to allow fluid to pass therethrough whilst acting as a damper to aid dissipation of heat from the heating element. Preferably, the heat exchange material is a fibrous material, such as a metal wool. More preferably, the heat exchange material is wire wool of non-corrosive metal, such as, for example, of stainless steel.
A second aspect of the present invention provides a method of manufacturing a heater that retards kettling, the method comprising attaching a first part of an enclosure unit to a second part of an enclosure unit to form a sealed enclosure, characterised by attaching a porous or perforated heat exchange material to the first part of an enclosure unit prior to its attachment to the second part creating a bore though said heat exchange material and inserting an electrical heating element through said bore.
Preferably, the second part is pressed onto the first part of the enclosure. Preferably, the heat exchange material is compressed or compacted either before or during its installation in the heater. The heat exchange material is preferably provided across a lower part of the enclosure unit corresponding in position to the location of the electrical heating element.
It is preferable for the bore to be created through the compacted heat exchange material by insertion of the heating element therethrough. For example, a cartridge having a tapered or pointed end may be inserted through the compacted medium to create the bore.
Preferably, the working fluid is water and is provided in an amount such that the heating element and heat exchange material are always immersed in liquid. However, the working fluid may be vapour elsewhere in the enclosure.
The heat exchange material may be contained within a compartment that covers the heating element The compartment may be in the form of a sleeve, more preferably a tubular sleeve. Preferably, one end of the sleeve is attachable to a boss of the heater to which the heating element is connected and the other end of the sleeve is closed. The compartment may be single or multiple walled. A twin-walled sleeve may be useful in the present invention.
The compartment may be provided with fins. The fins may be attached to the compartment or may be pressed therein.
The invention further provides a heating element in the form of a cartridge comprising an electrical heating element and a porous or perforated heat exchange material in contact with the heating element characterised in that the heating element is contained within an inner space defining component and the heat exchange material is contained within an outer space defining component surrounding the inner component. The inner space defining component may comprise a pair of spaced rings connected by rods to provide a space to receive a heating element. The outer component may comprise a pair of spaced rings connected by rods.
In one embodiment of the invention it may be possible to use both a wire wool heat transfer medium, such as of stainless steel wire wool and a particulate heat transfer medium, such as aluminium oxide. When using both types of heat transfer media, a twin-walled sleeve defining inner and outer compartments is desirably used, with one medium in the inner compartment and the other medium in the outer compartment. The wire wool is preferably placed in the inner compartment and the particulate medium in the outer compartment.
The compartment may be made of any suitable heat conducting material, such as steel, brass or chromium. The walls of the compartment may be solid or may be made from gauze.
Preferably, a pressure release valve is provided within the compartment, preferably being countersunk into the compartment walls at the end opposite the boss.
For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made by way of example only to the accompanying drawings, in which:

Figure 1 is a cross-sectional longitudinal view of a heating system according to one embodiment of the present invention;
Figure 2 shows a heating system according to a second embodiment of the invention; and
Figure 3 shows an anti-kettling cartridge.

Referring to Figure 1 of the accompanying drawings a heater 2 comprises a partially evacuated self-contained enclosure or unit 4 containing a heating element 8 towards the base thereof and a small amount of working fluid 6, such as water. Means 18 for evacuation of the unit, such as a valve, is also provided. The water 6 covers the region of the enclosure that contains the heating element. The heating element is contained within a region of compressed stainless steel wire wool 10. A gauze (not shown) may be provided around the heating element.
The wire wool provides a greater area for dissipation of the heat energy that is released from the heating element and prevents kettling of the water that surrounds the element whilst being lightweight and allowing heat to be transferred to the water. Such an arrangement has been found to reduce the wattage being dispersed from the heating element from around 217000 watts per m² (140 watts per sq. inch) to around 4.6 7131 watts per m² (watts per sq. inch) thereby reducing kettling. It is believed that air is able to travel up the fibres thereby preventing the explosion of trapped air that causes kettling.
The heater is manufactured by the compressed wire wool being attached to a first half of the enclosure unit and a second half of the unit is then pressed onto the first half. A bore is then inserted through the wool to create a passage for receiving the heating element. The bore is dimensioned such that the heating element fits snugly therein. This provides a very simple method of manufacturing of a heater, removing the need to manually coat/cover the heating element with a material prior to its insertion in the enclosure.
The heating element is a cartridge having a tapered or pointed end that is pushed through the compressed wire wool thereby creating the bore as the element is inserted therethrough. This ensures there is close contact between the element and the wire wool which is important to provide the necessary heat transfer. This provides an anti-kettling device that has minimal, if any, effect on the wattage of the device.
Turning to Figure 2 of the accompanying drawings, a heating element 20 is enclosed within a twin-walled metal gauze sleeve 22. The sleeve 22 has an inner compartment 24 and an outer compartment 26 surrounding the inner compartment. Within the inner compartment 24 is stainless steel wire wool and within the outer compartment 26 is an aluminium oxide paste. A pressure release valve (not shown) may be provided in the sleeve to prevent pressure build up.
Figure 3 of the accompanying drawings shows an anti-kettling cartridge 30 for use in a heating system of the type shown in Figure 1 of the drawings. The cartridge is designed to be slid onto a longitudinal heating element, such as element 8 of Figure 1.
The cartridge comprises a pair of smaller rings 32 connected by rods 34. The rings 32 are internally screw-threaded so as to be connectable to an externally screw-threaded ring of the heating element. The rings 32 and rods 34 provide a space to receive the heating element.
Stainless steel wire wool (not shown) is packed around the rings 32 and rods 34, so that it contains the heating element. The wire wool is contained by spaced larger outer rings 36 connected by rods 38. Each of the larger rings 36 is in the same place as one of the smaller rings 32.
The outer rings 36 and rods 38 may be replaced by a perforated cylinder.

Claims

A heater comprising a partially evacuated sealed enclosure (4) containing a working fluid and an electrical heating element (8) characterised in that the electric heating element is surrounded by a porous or perforated heat exchange material (10) contained within a compartment, said working fluid being provided in an amount such that in normal use the heating element and heat exchange material are always immersed in the liquid phase of the working fluid.
A heater as claimed in claim 1, characterised in that the heat exchange material (10) has pores or perforations.
A heater as claimed in claim 1 or 2, characterised in that the heat exchange material (10) is a fibrous material.
A heater as claimed in claim 3, characterised in that the heat exchange material (10) is a metal wool.
A heater as claimed in claim 4, characterised in that the heat exchange material (10) is a wire wool of non-corrosive metal.
A heater as claimed in claim 5, characterised in that the wire wool is of stainless steel.
A heater as claimed in claims 1 to 6, characterised in that the compartment is a sleeve (22).
A heater as claimed in claim 7, characterised in that one end of the sleeve is attached to a boss of the heater to which the heating element is connected and the other end of the sleeve is closed.
A heater as claimed in claim 7 or 8, characterised in that the sleeve (22) is twin-walled.
A heater as claimed in any one of claims 1 to 9, characterised in that the compartment has fins.
A heater as claimed in any one of claims 1 to 10, characterised in that the heat exchange material (10) comprises a wire wool and a particulate heat transfer medium.
A heater as claimed in claim 11, characterised in that the particulate heat transfer medium is aluminium oxide.
A heater as claimed in claim 11 or 12, characterised in that the core heat exchange material is in an inner compartment (24) and the other is in an outer compartment (26).
A heater as claimed in any one of the preceding claims, characterised in that the compartment is made of a heat conductive material.
A heater as claimed in any one of the preceding claims, characterised in that the compartment includes a pressure release valve.
A method of manufacturing a heater that retards kettling comprising attaching a first part of an enclosure unit to a second part of an enclosure unit to form a sealed enclosure, characterised by attaching a porous or perforated heat exchange material (10) to the first part of the enclosure unit prior to its attachment to the second part, creating a bore through said heat exchange material and inserting a heating element (8) through said bore.
A method as claimed in claim 16, characterised in that the second part is pressed onto the first part of the enclosure.
A method as claimed in claim 17, characterised in that the heat exchange material (10) is compressed or compacted either before or during its installation in the heater.
A method as claimed in claims 16,17 or 18, characterised in that the heat exchange material is provided across a lower part of the enclosure unit (4) corresponding in position to the location of the heating element (8).
A heating element in the form of a cartridge (30) comprising an electrical heating element and a porous or perforated heat exchange material in contact with the heating element characterised in that the heating element is contained within an inner space defining component and the heat exchange material is contained within an outer space defining component surrounding the inner component.
A heating element as claimed in claim 20, characterised in that the inner space defining component comprises a pair of spaced rings (32) connected by rods (34).
A, heating element as claimed in claim 20 or 21, characterised in that the outer space defining component comprises a pair of spaced rings (36) connected by bars (38).
A heating element as claimed in claim 20 or 21, characterised in that the outer space defining component is a perforated or apertured cylinder.
A heating element as claimed in any one of claims 20 to 23, characterised by inclusion of a metal wool heat exchange material.
A heating element a claimed in claim 24, characterised in that the metal wool is of stainless steel.
A heating element as claimed in any one of claims 20 to 24, characterised by the inner space defining component having means for screw-threadingly fixing the heating element (8) therein.