BACKGROUND TO THE INVENTION Typically in a heat exchanger a heating or cooling fluid will be constrained to flow in a tube system defining one fluid path while fluid to or from which heat is being transferred will be constrained to flow in another tube defining a second path, the respective flow paths typically being in opposite directions.

Such heat exchangers have the disadvantage of heat transfer being through two thicknesses of the material of the respective tubes.

It is an object of the present invention to provide a heat exchanger tracking which will overcome or at least obviate disadvantages in heat exchangers available to the present time or which at least will provide the public with a useful choice.

Further objects of this invention will become apparent from the following description.

DISCLOSURE OF THE INVENTION According to one aspect of the present invention a heat exchanger inclues a first fluid flow path defined by fluid flow through a conduit means and wherein the track of a second fluid flow path is defined substantially by the configuration of the said conduit means.

According to a further aspect of the present invention a method of providing separate fluid flow paths in a heat exchanger includes providing a first fluid flow path through a conduit means and configuring

said conduit means so as to define said second fluid flow path between portions of said conduit means.

Preferably, the conduit means of either of the above two paragraphs inclues at least one tube with a substantially vertical or substantially horizontal spiral configuration.

According to a further aspect of the present invention there is provided a heat exchanger and/or a method of providing fluid flow paths in a heat exchanger substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Further aspects of the present invention which should be considered in all its novel aspects will become apparent from the following description given by way of example of possible embodiments thereof and in which reference is made to the accompanying drawings wherein: Figure 1: Shows diagrammatically a fluid conduit according to one possible embodiment of the invention; Figure 2a: Shows the conduit of Figure 1 with associated fitments; Figures 2b and 2c: Show plan and cross section views of the Conduit of Figure 2a; Figure 3: Shows the conduit of Figure 1 and 2 with spacers fitted; Figure 4: Shows very diagrammatically a cross sectional view through a heat exchanger according to one possible embodiment of the invention;

Figure 5: Shows housing means suitable for use with the conduit of the preceding Figures; Figure 6: Shows diagrammatically a perspective view of a heat exchanger according to one possible embodiment of the invention; Figure 7: Shows a heat exchanger according to a further possible embodiment of the invention; Figure 8: Shows a cross sectional view through a possible embodiment of the invention; Figure 9: Shows a cross sectional view through a further possible embodiment of the invention, with a further modification indicated in outline.

Referring firstly to Figure 1 a conduit for use in a heat exchanger according to one possible embodiment of the invention is referenced generally by arrow 1 and is shown in this instance as being a tube 2 which is configured in the form of a substantially horizontal coil so that fluid can flow in the direction indicated by arrows I and O. The coil 2 by its substantially horizontal configuration is inherently providing a track 3 between adjacent turns of the coil and in this embodiment of the invention the track 3 provides the second fluid flow path indicated by arrows A from the centre 6 of the coil to exit as indicated on the left hand side of the coil 2. It is seen that in this embodiment of the invention the flow of the second fluid in the direction of arrows A is in a counter-flow direction to the direction of the first fluid passing through the coil 2.

In Figures 2a, 2b, 2c the coil 2 is shown mounted on a base plate 4 and with a number of spacers 5 around the circumference of the coil to maintain it in position. Preferably the coil 2 and/or spacers 5, baffle plates and the like may be sandblasted electroplated, or deformed

or configured, such as dimpled or helical, so as to enhance the heat transfer. The spacers 5 are shown providing saddles 60 to space the tracks 3 apart and to hold down and to maintain the wall of the track 3.

Spot welds or the like 70 may be provided throughout the structure as appropriate, suitably for each of the flat spacer portions 61. The tube 2 may be of any suitable size or dimension for example circular, oval or helical. In Figure 3 a cover 7 is shown positioned over the coil 2 with spacer baffles 8 provided on the upper surface of the plate 7.

Referring to Figure 4 the heat exchanger 1 is shown provided within a metal or plastic container 9 with a pair of the coils 2 mounted one above the other and separated by the spacer baffles 8.

It is seen that in one possible flow arrangement a fluid can enter the track defined by the spacer baffles 8, indicated as track B through the central area 6 and to the track defined between the portions of the bottom coil 2 before proceeding through the bottom coil 2 and then the upper coil 2 before exiting. During this flow the fluid will be transferring heat to or absorbing heat from the other fluid flowing through the coils 2 themselves preferably in an opposite direction.

In Figure 5 the housing 9 is shown having a central core 10 and also an upper portion 11. A manifold 71, shown in outline, may be butted into the housing 9 to provide inlet and outlet pipe apertures 141, 151,161 and a baffle 62 to separate the inlet and outlet fluid flows.

In Figure 6 the assembly is shown referenced generally by arrow 12 as including an externai housing 13 with inlet connectors 14 on the one side a pair of each of which connect with a respective coil 2 and outlet connectors 15 a pair of which also connect with a respective coil 2. Centrally positioned in this example are the inlet and outlet connectors 16 for the fluid which will flow in the tracks defined between the portions of the coils 2. The housing 13 may suitably be a foamed plastic case providing both strength and insulation.

In one example one or more coils 2 can be connected with a

source of a refrigerant such as glycol and the connections 16 can be supplie with a product such as beer or milk flowing in the opposite direction and being cooied down to a required temperature as it flows through the heat exchanger 12 and is controlled by suitable control vaives provided for the connections 16.

Referring to Figure 7 in an alternative embodiment heat exchanger 17 inclues a housing 18 which may have an inlet 12 and an outlet 19 for one fluid and an inlet 21 and outlet 22 for a second fluid.

In this embodiment the one or more coils may be configured substantially vertically so that the track for a second fluid defined in the portions of the coil is also defined substantially vertically. Thus in Figure 8 a pair of substantially vertical coils 23,25 are shown positioned adjacent one another separated by respective spacers or formers 27 with the coils 23,25 respectively providing substantially vertical fluid flow tracks or paths 24 and 26. A first fluid such as a refrigerant gas or liquid may therefore pass through both coils 23,25 and the second fluid to be heated or cooled can pass in the opposite direction between the inlet and outlet connections 20,19 and through the tracks 24,26 between the portions of the respective coils 23,25.

Once again the coils 23,25 may be of any suitable shape and dimension and may suitably be provided with a helical configuration on their outer surface in one embodiment. Additionally the coils 23,25 may be capable of being opened out or closed so as to adjust their lengths and the respective sizes of the track areas between the coils and thereby change the capacity of flow through the heat exchanger 17 with a commensurate change in the size of the external housing 18 if appropriate. The housing 18 and the spacers or formers 27 may suitably be of a plastics material but other materials may be used.

Referring to Figure 9 in an alternative embodiment only a single coil 23 is provided for the heat exchanger 17 defining a single track 24 between adjacent turns of the coil 23 through which one of the fluids flows so as to heat or cool the second fluid flowing through the coil 23

between its inlet and outlet 21,22.

Any suitable material could be used for the tubes 2,23,25 including copper, stainless steel, titanium or the like.

It would be appreciated that in all the embodiments of the invention there is only a single thickness of tube material separating the two fluids as they travel along their respective flow paths and accordingly it has been found that an improved efficiency of thermal transfer can be achieved.

Where in the foregoing description, reference has been made to specific components or integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope of the appended claims.