WO2004008040A1

WO2004008040A1 - Improvements in and relating to heaters

Info

Publication number: WO2004008040A1
Application number: PCT/GB2003/002877
Authority: WO
Inventors: Leo Lamb
Original assignee: Lambco Holdings Ltd; Leo Lamb
Priority date: 2002-07-13
Filing date: 2003-07-04
Publication date: 2004-01-22
Also published as: EP1552226A1; ATE354066T1; DE60311854T2; EP1552226B1; DE60311854D1; AU2003251157A1

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

Title: Improvements in and relating to heaters

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 phrase 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.

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 sealed enclosure containing a heating element, the enclosure containing a heat transfer fluid characterised in that the heating element is surrounded by a confined heat transfer medium.

The confined heat transfer medium increases the area of heat transfer from the element to the fluid thereby retarding kettling. The heat transfer

medium 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 transfer medium is a fibrous material, such as a metal wool. More preferably, the heat transfer medium 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 confined heat transfer medium to a first part of an enclosure unit, attaching a second part of the enclosure unit to said first part to form a sealed enclosure around said transfer medium, creating a bore through said confined heat transfer medium and inserting a heating element through said bore.

Preferably, the second part is pressed onto the first part of the enclosure. Preferably, the confined heat transfer medium is compressed or compacted either before or during its installation in the heater. The heat transfer medium is preferably provided across a lower part of the enclosure unit corresponding in position to the location of the heating element.

More preferably, according to the invention the heating element is in the form of a cartridge.

It is preferable for the bore to be created through the compacted heat transfer medium 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 heater comprises a partially evacuated unit containing an amount of working fluid, the unit having means for evacuation thereof. Preferably, the working fluid is water and is provided in an amount such that the heating element and heat transfer medium are always immersed in liquid. However, the working fluid may be vapour elsewhere in the enclosure.

The confined heat transfer medium 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 inner space defining component and 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 bars to provide a space to receive the heat transfer medium. The outer component may alternatively be a cylinder that is perforated or formed with apertures. 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 140 watts per sq. inch to around 4.6 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.

In a preferred embodiment of the present invention, 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

1. A heater comprising a sealed enclosure containing a heating element and a heat transfer fluid, characterised in that the heating element is surrounded by a confined heat transfer medium.

2. A heater as claimed in claim 1 , characterised in that the heat transfer medium has pores or perforations.

3. A heater as claimed in claim 1 or 2, characterised in that the heat transfer medium is a fibrous material.

4. A heater as claimed in claim 3, characterised in that the heat transfer medium is a metal wool.

5. A heater as claimed in claim 4, characterised in that the heat transfer medium is a wire wool of non-corrosive metal.

6. A heater as claimed in claim 5, characterised in that the wire wool is as stainless steel.

7. A heater as claimed in any one of claims 1 to 6 comprising a partially evacuated unit containing an amount of working fluid, the unit having means for evacuation thereof.

8. A heater as claimed in claim 7, characterised in that the working fluid is water and is provided in an amount such that the heating element and heat transfer medium are always immersed in liquid.

9. A heater as claimed in any one of claims 1 to 8, characterised in that the confined heat .transfer medium is contained within a compartment that covers the heating element.

10. A heater as claimed in claim 9, characterised in that the compartment is a sleeve.

11. A heater as claimed in claim 10, 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.

12. A heater as claimed in claim 10 or 11 , characterised in that the sleeve is twin-walled.

13. A heater as claimed in any one of claims 9 to 12, characterised in that the compartment has fins.

14. A heater as claimed in any one of claims 1 to 13, characterised in that the heat transfer medium comprises a wire wool and a particulate heat transfer medium.

15. A heater as claimed in claim 14, characterised in that the particulate heat transfer medium is aluminium oxide.

16. A heater as claimed in claim 14 or 15, characterised in that the core heat transfer medium is in an inner compartment and the other is in an outer compartment.

17. A heater as claimed in any one of claims 9 to 16, characterised in that the compartment is made of a heat conductive material.

18. A heater as claimed in any one of claims 9 to 17, characterised in that the compartment includes a pressure release valve.

19. A method of manufacturing a heater that retards kettling comprising attaching a confined heat transfer medium to a first part of an enclosure unit, attaching a second part of the enclosure unit to the first part to form a sealed enclosure around the heat transfer medium, creating a bore through said confined heat transfer medium and inserting a heating element through said

bore.

20. A method as claimed in claim 19, characterised in that the second part

is pressed onto the first part of the enclosure.

21. A method as claimed in claim 20, characterised in that the confined heat transfer medium is compressed or compacted either before or during its

installation in the heater.

22. A method as claimed in claims 19, 20 or 21 , characterised in that the heat transfer medium is provided across a lower part of the enclosure unit corresponding in position to the location of the heating element.

23. A heating element in the form of a cartridge comprising an inner space defining component for receiving a heating element and an outer space defining component for receiving a heat transfer medium in contact with the heating element.

24. A heating element as claimed in claim 23, characterised in that the inner space defining component comprises a par of spaced rings connected by rods.

25. A heating element as claimed in claim 23 or 24, characterised in that the outer space defining component comprises a pair of spaced rings connected by bars.

26. A heating element as claimed in claim 23 or 24, characterised in that the outer space defining component is a perforated or apertured cylinder.

27. A heating element as claimed in any one of claimed 23 to 26, characterised by inclusion of a metal wool heat transfer medium.

28. A heating element as claimed in claim 27, characterised in that the metal wool is of stainless steel.

29. A heating element as claimed in any one of claims 23 to 28, characterised by the inner space defining component having means for screw-threadingly fixing the heating element therein.

30. A cartridge for receiving a heating element comprising an inner space defining component for receiving the heating element and an outer space defining component for containing a heat transfer medium.

31. A cartridge as claimed in claim 30, characterised in that the heat transfer medium is a wire wool.