GB2457935A

GB2457935A - Heating appliance having at least one tubular heat exchange member of non-circular cross-section that is twisted about its longitudinal axis

Info

Publication number: GB2457935A
Application number: GB0803785A
Authority: GB
Inventors: Saffet Kalender
Original assignee: PITACS Ltd
Current assignee: PITACS Ltd
Priority date: 2008-02-29
Filing date: 2008-02-29
Publication date: 2009-09-02
Anticipated expiration: 2028-02-29
Also published as: GB2457935B; GB0803785D0

Abstract

A heating appliance comprises at least one tubular heat exchange member 1 of non-circular cross-section that is twisted about its longitudinal axis. A plurality of parallel twisted tubular heat exchange members 1 may be provided and joined at adjacent ends by pipes (2, 3 fig 1B). The tubular members 1 may be rectangular, twisted in the same direction and may have different surface finishes on different sides. A central portion of the tubes may not be twisted. The twist may be 90, 180 or other multiples of 90 degrees (fig 3A). The appliance may be connected in a water circulation central heating system. A hook (7, fig 3A) may be attached proximate an end of the tubes 1 so that towels may be hung on them. The tubes 1 may be manufactured by clamping (14, fig 4D) a tube 1 between its ends and twisting opposite ends of the tube 1 in opposite directions via drives (15). The tubes 1 may be temporarily filled with fine granular sand (11, fig 4B) to prevent collapsing of the tubes during manufacture.

Description

A hEATING APPLIANCE This invention relates to a heating appliance comprising a path for hot fluid, usually water, defined by at least one tubular heat exchange member. The invention was conceived for use in so-called "radiators" in water circulation central heating systems.

Although this term "radiator" will be used in this specification it will be understood that the majority of heat from such "radiators" is dissipated by convection rather than radiation.

In the design of radiators, it is important to reduce as much as possible the resistance to fluid flow to maximise the rate at which heat can be supplied by the flow of fluid to the radiator. As a general rule, sharp bends increase resistance and arc therefore best avoided. It is also important to select the material from which the heat exchange tubes are fabricated so as to provide an efficient transfer of heat from the fluid, through the walls of the tubes and thence into the air of a room to be heated.

Frequently there is a conflict between the above requirements for efficient heat transfer and the requirements for stylish appearance, particularly when the radiator is required for use in domestic and other non-industrial environments.

The invention addresses the problem of allowing the designer freedom to create visually appealing designs whilst also providing efficient heat transfer.

According to the invention there is provided a heating appliance comprising a path for hot fluid defined by at least one tubular heat exchange member of non-circular cross-section characterised in that the said tubular member is twisted about its axis.

By constructing the heat exchange tube with a twisted configuration it has been found that reduced resistance to flow and improved heat output can be achieved. The technical reasons for these effects are not yet thoroughly understood. However, it is known (e.g. from W0850 1692) to use twisted ribbons within a heat exchange pipe to produce a swirling effect and thereby causing the fluid to impinge vigorously against the heat conducting walls and it is conjectured that the invention produces a similar effect.

Thus, the twisted heat exchange pipes can provide improved technical performance whilst also presenting a unique visual effect. The improved technical performance in turn allows other aesthetically motivated design changes to be made without detriment to efficiency as compared with more conventional designs.

In a practical embodiment it is envisaged that two or more similar twisted heat exchange tubes will be assembled in parallel configuration with suitable pipes used to connect adjacent ends of the tubes.

For visual effect, the heat exchange tubes are preferably twisted in the same direction.

In one design, different sides of each tube have respective different surface finishes.

The twist causes these different finishes to be visible at different positions along the tube, resulting in a unique aesthetic effect. The effect is further improved if a central portion of each tube is left untwisted.

The degree of twist is preferably 90 degrees or a multiple thereof for convenience of attachment of adjoimng ends.

The tubes are preferably of rectangular cross-section. This allows a hook to be attached, preferably by welding, to a relatively narrow forward facing tube edge.

Objects such as towels can be supported by these hooks so that they hang close to the heat exchange pipes for drying.

The incorporation of hooks into the design of the radiator in this way is believed to have independent inventive significance and therefore, according to a second aspect of this invention, there is provided a heating appliance comprising an array of parallel upright heat exchange elements and at least one hook attached by welding to one of the elements at or near a top end thereof so that objects requiring drying can hang on the hook and lie alongside the heat exchange elements.

The twisted pipes are preferably made starting from a straight untwisted pipe of rectangular cross-section. Initially, a stainless steel pipe of rectangular cross-section was finished by polishing on two adjacent sides and brush-finishing to give a mat appearance on the other two sides. Twisting of this pipe by holding and turning opposite ends failed to provide a uniform twist along the length of the tube and tended to cause the tube to collapse inwardly. An alternative process involving passing the tube through sequential sets of rollers arranged at an angle was impracticable because ii damaged the surface finish which has to be created while the tubes are flat. The problems were overcome by clamping the tube at a position between its ends and then twisting opposite ends in opposite directions. To avoid collapsing of the tube during this process it was temporarily filled with very fine granular sand.

One way in which the invention may be performed will now be described by way of example with reference to the accompanying drawings in which: -Figs 1A, lB and 1C are respectively front, side and rear elevations of a radiator constructed in accordance with the invention employing six heat exchange tubes, each twisted through an angle of 90 degrees; Fig 1D is a vertical cross-section through a top portion of thc radiator shown in the previous figures, illustrating the connection between vertical tubes; Fig 2 is a side elevation equivalent to that of Fig 1 B, of a second design similar to that of Figs 1A, 1B, 1C and 1D; Figs 3A and 3B are views similar to Figs IA and lB but showing a third design wherein the heat exchange tubes are twisted through an angle of 360 degrees; and Figs 4A to 4D shows various stages during the twisting of one of the heat exchange tubes for use in any of the embodiments of Figs 1 to 3.

Referring first to Figs 1A, lB and 1C, the illustrated radiator is fabricated from six vertical stainless steel tubes 1. Each tube is of rectangular cross-section so that it has two opposite wide faces and two opposite narrow edges. Each tube is finished with a highly polished surface on one wide side and an adjacent narrow edge; and a mat "brushed" fmish on the other side and edge. The ends of the tubes 1 are closed by plates IA (Fig ID) welded to their ends and all of the tubes are twisted in the same direction, through 90 degrees.

The effect of the twist is that, at the bottom of the radiator, the polished wide sides face forward as viewed in Fig 1 A whilst, at the top of the radiator, their polished narrow edges face forward. The twist ensures that unpolished surfaces arc also visible from the front, depending on the angle of view, giving an distinctive visual appearance.

The bottom end of each tube has a hole drilled through its rearward facing wide side through which it communicates with an inletloutlet tube 2, also of rectangular section stainless steel. The twisted vertical tubes arc welded to this inlet tubc so as to provide a watertight seal between the tubes 1 and 2. The inlet tube 2 is blocked internally at its centre so that hot water entering at one end of the tube 2, as shown by the arrows has to pass up a first set of three vertical tubes and then passes down through the remaining tubes. The tube 2 also acts as a supporting structure for the bottom ends of the vertical tubes.

The top ends of the tubcs 1 also have drilled holes in their wide sides are welded to a lateral tube 3 which acts only as a mechanical support in this particular configuration.

They are also drilled with holes in their wide sides and joined by short connection tubes 4 seen best on Fig 1D. These are welded into holes drilled in the wide sides of the vertical tubes near the top ends thereof. The welds 5 may be covered by decorative ferrules (not shown).

The radiator is adapted to be mounted on a wall by mounting points shown at 6 on Fig 1C.

Fig 2 shows a modified vertical tube similar to those of Figs I to which a hook 7 has been welded to the narrow edge at the top end. This allows damp towels or garments to be hung in a position where they lie close to the vertical tubes where they can be allowed to dry.

Figs 3A and 3B illustrate another variant where each of nine tubes 1A is twisted through 360 dcgrccs so that the wide side of each tube faces the front at the top and bottom of the railiator. In this design the bottom of each tube is connected to an inlet/outlet pipe 8 similar to the pipe 1 of Figs 1. The top of each tube is connected to a horizontal pipe 9 that serves the function of the tubes 4 of Fig 1.

The pipes 8 and 9 carry mounting bolts for connection to wall brackets (not shown).

In a variation to the design of Figs 3A and 3B, a central portion of each pipe may be left untwisted so as to expose a substantially flat central area in the centre of the radiator to give a highly reflective visual effect in that area.

In the illustrated constructions the heat exchange tubes are made from rectangular-section stainless steel tubing. First, the ends of the tubes are closed by welding on the plates IA (for simplicity of illustration these plates are not shown separately on Fig 4). Holes 10 are then drilled close to the ends and the tubes are then surface finished by polishing on one side and edge and with a brushed effect finish on the other side and edge. The tubes are then filled with fine sand 11, as shown in Fig 4B, and plugs 12 are then welded into the holes and the tube is placed into a machine as shown in Fig4D.

The machine comprises a bed 13 defining a sliding track that carries a clamping mechanism 14 and two drives 15. The clamping mechanism 14 comprises a block 14A that slides along the bed and can be locked at a chosen position using the locking handle shown. The block 14A houses a rotor 14B defining a slot designed to receive a tube to be twisted and this rotor can be selectively released or locked against rotation using locking screw 14C.

To operate the machine, the sand filled tube is placed in position as shown in the drawing and the block 14A slid to a desired position e.g. the centre of the tube. The block and rotor are then locked and the drives 15 operated so as to exert opposite turning forces on the ends of the tubes. In this way each half of the tube is twisted through the desired angle e.g. 180 degrees plus a margin to allow for springing back after the torsion has been released. After the initial twisting operation, the block l4A and rotor I 4B are unlocked and the block can be moved along the track noting the angle of twist by reading a dial as illustrated on the block and graduations (not shown) on the bed. If there are any deviations from the desired twist angle at different points along the tube, corrections can be made by re-clamping the block and rotor at any position and again operating the appropriate drive. This method allows a central part of the tube to be left untwisted by first operating the left-hand drive 15 with the clamping mechanism left of centre as illustrated; and then moving the clamping mechanism to a position right of centre, re-clamping it, and operating the right-hand drive 15.

When the desired twist has been achieved, the tube is removed, holes are drilled where required to make connections with the top and bottom feed pipes, and the sand is removed.

Claims

CLAIMS1. A hcating appliance comprising a path for hot fluid defined by at least one tubular heat exchange member of non-circular cross-section characterised in that the said tubular member is twisted about its axis.
2. A heating appliance according to Claim 1 characterised by more than one twisted tubular heat exchange member arranged in parallel configuration and joined at adjacent ends by pipes.
3. A heating appliance according to Claim 2 characterised in that the tubular elements are twisted in the same direction.
4. A heating appliance according to any preceding claim characterised in that the or each twisted member has surface finishes of different appearances on respective different sides.
5. A heating appliance according to any preceding Claim characterised in that the or each element is of rectangular cross-section.
6. A heating appliance according to any preceding Claim characterised in that the or each element has a central portion that is not twisted.
7. A heating appliance according to any preceding Claim characterised in that the or each element is twisted through 90 degrees.
8. A heating appliance according to any preceding Claim characterised in that the or each element is twisted through 180 degrees or other multiple of 90 degrees.
9. A heating appliance according to any preceding Claim and designed for connection in a water circulation central heating system.
10. A heating appliance according to Claim 9 when dependant on Claim 5 characterised in by a hook attached to a relatively narrow edge defined by the or one of the rectangular-section tubular members.
11. A method of making a heating appliance according to any preceding Claim comprising the steps of clamping a tube at a position between its ends and then twisting opposite ends in opposite directions.
12. A method of making a heating appliance according to Claim 11 including the step of filling the tube with fine granular material before twisting.
13. A heating applianec comprising an array of parallel upright heat exchange elements and a hook attached by welding to one of the elements at or near a top end thereof so that objects requiring drying can hang on the hook and lie alongside the elements.