AU778311B2

AU778311B2 - Heat exchanger

Info

Publication number: AU778311B2
Application number: AU34307/02A
Authority: AU
Inventors: Alan Paul Baker
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-04-11
Filing date: 2002-04-11
Publication date: 2004-11-25
Anticipated expiration: 2022-04-11
Also published as: AU3430702A

Description

AUSTRALIA

Patents Act 1990 ALAN PAUL BAKER COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Heat exchanger The following statement is a full description of this invention including the best method of performing it known to us:- Psne~:~; BQ ~a~a d gccuments Ja pgn 4~ Field of the Invention This invention relates to a heat exchanger. In particular, the invention relates to heat exchangers for liquid or gaseous heat exchange to fluids and more particularly, to heat exchangers for cooling liquids, particularly beverages such as beer or soft drinks, although the principles of the invention could equally be applied to heating fluids.

Background of the Invention Heat exchangers are commonly used in bars and hotels to chill beer, typically from a temperature of around 200 to 300 to around 20 for sale to patrons. Such heat exchangers are usually installed under a traditional bench or hotel or club bar top.

Thus, there is requirement for the heat exchanger to be relatively compact to fit in the available space. Existing technology for cooling beer, relies on the expansion of an R12 refrigerant in a vessel in order to cool the beer. However, use of refrigerants such as

R

1 2 is no longer environmentally acceptable due to their reputation for damaging the ozone layer. Consequently, there is a need to provide a more environmentally friendly, yet compact, means for chilling beer or other fluids.

Whilst there are a number of existing types of heat exchanger, typically these devices are quite complex and expensive to produce especially when more than one fluid stream is to be cooled or heated from a common service fluid media. In addition, using existing techniques, it is difficult to produce heat exchangers of a sufficiently OO compact size to be suited for installation under a traditional bench or hotel or club bar.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a s context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia before the priority date f1W. of each claim of this application.

.0 Summary of the Invention In a first broad aspect, the present invention provides a heat exchanger comprising: a housing defining an inlet and an outlet for entry and exit of a cold or hot fluid service media, the inlet and outlet being adjacent opposite longitudinal ends of the housing; a single helical coil defining a longitudinal axis and defining a single product flow path for a fluid, the coil having a plurality of turns and being located in the housing and having an inlet and an outlet for entry and exit of the fluid product into the coil to be heated or cooled, the inlet being located near one longitudinal end of the coil, the outlet being located near the other longitudinal end of the coil characterised by: a plurality of baffles extending across the vessel generally perpendicular to the longitudinal axis of the coil, the baffles being located between adjacent turns of the helical coil, each baffle defining an aperture or apertures for the passage of service fluid, the arrangement being such that fluid service media passing through the vessel from the inlet to the outlet is forced to travel along a generally serpentine path causing turbulent flow..

In a preferred embodiment, a helical coil has a generally circular cross-section defining an interior and an exterior and the vessel has an annular cross-section whose interior dimensions are slightly larger than the exterior dimensions of the helical coil.

The baffles are preferably circular sheets of rigid material such as plastics, stainless steel, or the like, which form a membrane type baffle and are relatively a tight fit in the vessel so that they seal against the interior wall of the vessel.

Typically, a cut-out portion is defined in the exterior perimeter of the baffle which in conjunction with the interior wall of the vessel, defines an aperture. The r diameter of the helical coil and the area of the aperture are designed for the prescribed heat transfer duty.

20, 38; Brief Description of the Drawing A specific embodiment of the invention will now be described by way of example only, and with reference to the accompanying drawing in which: Figure 1 is a partial perspective view of a heat exchanger embodying the present 25 invention.

D e 7 Detailed Description of a Preferred Embodiment ~Referring to the drawings, Figure 1 shows a heat exchanger 10 comprising a helical coil 12 located inside a housing 14 in the form of a hollow cylinder having an annular cross-section. The coil defines entry and exit points 16, 18 respectively, where fluids to be heated or cooled can enter and exit the coil, or vice versa as the entry and exit points, can be reversed, if desired. The vessel 14, which encloses the helical coil 12, itself defines entry and exit points 20, 22 for fluid media for cooling (or heating) fluid in the helical coil 12. The entry and exit points are located at the base and top of the vessel, respectively. The helical coil and vessel may made of any suitable material, although O0 eoo oo e o o typically, stainless steel will be used for the tube when processing beverage type products.

The diameter of the tubes forming the coil and the length of the coil and the size of the housing can be varied to suit the particular heat exchange requirements of the system.

A series of five membrane type baffles shown as 24A-E, are inserted between turns of the helical tube spaced apart along the length of the helical coil, as shown in Figure 1. The baffles seal against the inner surface of the vessel 14 but each defines an aperture 26A to E for the passage of service fluid inside the vessel 14. The aperture 26 allows flow in the vessel, past the baffle, inside of the coil, and also outside of the coil in the annular gap between the coil and the interior wall of the vessel 14. As shown in Figure 1, the apertures 26 of the adjacent baffles, are disposed on opposite sides of the vessel spaced apart by approximately 1800. There are five baffles in the vessel shown spaced apart by three turns of the coil. However, fewer or more baffles could be provided depending on the requirements of the system and the spacing could be varied.

The entire vessel containing the coil will typically been enclosed in an insulated box.

In use, fluid such as beer to be cooled, enters the helical coil 12 at the inlet 16 and exits at 18. The service fluid media for cooling the beer enters the vessel 14 at 20 and leaves via the exit 22. For cooling beer, glycol is the preferred coolant, although other coolants such as chilled water or ethanol could be used. Glycol has the advantages that it is non toxic which is particularly significant when cooling beverages and, in contrast with the ethanol, is not flammable.

As the glycol enters the top of the vessel along the baffle 26, it will be apparent that the glycol has to travel across the top of the vessel to the aperture 26 in order for it to pass further down the vessel. The glycol will then either travel between two adjacent coils or over the top of the coils to the outer side of the helical coil 12, or through the interior of the coil. In either case, the glycol is forced by the baffles along a serpentine path. The coolant in the interior of the coil, travels across the top of the second baffle 24B towards aperture 26B. The coolant which is passing down the outside coil, also has to travel around the coil by 1800 to reach the same aperture 26B in order to pass further down the vessel into the space in between that baffle and the next baffle 24C. The process continues until the coolant has passed down the vessel to the exit 22. This serpentine path which the coolant is forced to travel, creates turbulent flow in the heat exchanger over both the inner and outer surfaces of the entire helical coil and provides substantial heat transfer between the coolant fluid and the beer in the helical coil. Without the baffles, coolant would simply travel down from the top of the vessel from the entrance 18 to the exit 22, most of the flow being substantially linear and very little heat transfer would take place between the bulk of the coolant passing down the centre of the heat exchanger to the fluid in the coil. A much larger and more expensive heat exchanger would be required which would be unlikely to fit in the space available.

Obviously, although the above description relates to the cooling of beer using chilled glycol, the heat exchanger could be used for cooling other fluids.

It could utilise other coolants, liquid or gaseous or could be used for heating fluids rather than cooling fluids.

A number of the heat exchanger units shown in Figure 1 could be assembled together all sharing a common service fluid line. A plurality of units would allow for multiple fluid streams of different fluids to be heated and cooled simultaneously, such as may be required in an application such as a hotel, bar or club. The number of apertures in the baffles could be varied, as could their orientation with the requirement being that the baffles should provide a serpentine path down pass the coil such as to result in generally turbulent flow of the cooling medium. Each baffle might provide two apertures so that apertures in adjacent baffles are 900 apart.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

1. A heat exchanger comprising: a housing defining an inlet and an outlet for entry and exit of a cold or hot fluid service media, the inlet and outlet being adjacent opposite longitudinal ends of the housing; a single helical coil defining a longitudinal axis and defining a single product flow path for a fluid, the coil having a plurality of turns and being located in the housing and having an inlet and an outlet for entry and exit of the fluid product into the coil to be heated or cooled, the inlet being located near one longitudinal end of the coil, the outlet being located near the other longitudinal end of the coil characterised by: a plurality of baffles extending across the vessel generally perpendicular to the longitudinal axis of the coil, the baffles being located between adjacent turns of the helical coil, each baffle defining an aperture or apertures for the passage of service fluid, the arrangement being such that fluid service media passing through the vessel from the inlet to the outlet is forced to travel along a generally serpentine path causing turbulent flow. .1I!

2. A heat exchanger as claimed in claim 1 wherein the helical coil has a generally circular cross-section defining an interior and an exterior and the vessel has an annular .18! cross-section whose interior dimensions are slightly larger than the exterior dimensions ji'j 20 of the helical coil. 01*

3. A heat exchanger as claimed in claim 1 or 2 wherein the baffles are generally circular sheets of material such as plastics or stainless steel which form a membrane 00 type baffle which is a relatively tight fit in the vessel so that they seal against the interior wall of the vessel. 25

4. A heat exchanger as claimed in any preceding claim wherein a cut-out portion is ov.. defined in the exterior perimeter of the baffle which in conjunction with the interior wall of the vessel, defines an aperture.

A heat exchanger as claimed in any preceding claim wherein a single cut out S.portion is defined in each baffle and the cut-out portions in adjacent baffles are spaced apart by 90 to 270, preferably about 180 degrees.

6. A heat exchanger as claimed in claim 5 wherein the cut out portions in adjacent baffles are spaced apart by about 1800. 9 999 99. 9 9o99 9oo 9o 9o*o 9oo 99 9o o o o

7. A heat exchanger substantially as hereinbefore described with reference to and/or as shown in the accompanying drawing. Dated this second day of April 2004 Alan Paul Baker Patent Attorneys for the Applicant: F B RICE CO *go *11