GB2475582A

GB2475582A - Refrigerant coil for beverage chillers

Info

Publication number: GB2475582A
Application number: GB201013589A
Authority: GB
Inventors: Michael John Filmer
Original assignee: M F REFRIGERATION Ltd
Current assignee: M F REFRIGERATION Ltd
Priority date: 2010-08-13
Filing date: 2010-08-13
Publication date: 2011-05-25
Anticipated expiration: 2030-08-13
Also published as: GB201013589D0; GB2475582B

Abstract

A refrigerant coil 10 for a chill tank 29, for example for cooling beverages, comprises two layers of sheet metal bonded together, at least one of the layers being shaped so that the layers define between them one or more conduits 15 for a refrigerant. The metal is preferably aluminium or aluminum with the layers of sheet metal being welded together. The coil is preferably bent into a free standing shape so that it can be simply inserted into the tank without additional support so as to form an ice bank in use (figure 3, not shown).

Description

I

REFRIGERANT COIL FOR BEVERAGE CHILLERS AND THE LIKE

This invention relates to a refrigerant coil, and in particular to a coil suitable for cooling a chill tank of the type used for cooling beverages prior to consumption.

Premises selling chilled beverages such as beers and soft drinks on draft typically use a chill tank filled with liquid, usually water, around which is a coil through which a fluid refrigerant is circulated to cool the contents of the tank. A beverage is circulated through another coil immersed in the tank to cool it, and then pumped through a conduit, typically in a chilled line and as a "python" to a dispensing point. A system of this type is described and illustrated in GB-A-2440202. This system uses a chill tank of the type known as an ice bank cooler, described in more detail in GB-A-2419176.

A conventional ice bank cooler comprises a tank of water provided with a stirrer to cause the water to circulate in a preferred direction. Around the inner walls of the tank is a coil of tubing, usually copper, through which a fluid refrigerant is circulated. This coil typically acts as the evaporator of a refrigeration circuit. The refrigerant is expanded and vaporized through an expansion valve, cools rapidly by the absorption of latent heat and circulates through the evaporator at several degrees below zero centigrade, causing a wall of ice several centimetres thick to form around the inner walls of the tank. The coil or coils through which beverages flow is immersed in the cooled water within the ice bank.

Since the late 20th century, environmental objections to the use of chlorofluorocarbon refrigerants has led to their replacement by hydrocarbon refrigerants, usually butane-or propane-based. These are becoming increasingly expensive, as is copper. Accordingly, there is a need for a chill tank design of simplified construction, and for one that uses smaller quantities of expensive materials.

The present invention provides a refrigerant coil for a chill tank comprising two layers of sheet metal bonded together, at least one of the layers being shaped so that the layers define between them one or more conduits for a refrigerant.

The layers of sheet metal are preferably welded together. The preferred metal is aluminium, which is considerably cheaper than copper as well as having high thermal conductivity and being easy to weld. Aluminium alloys may also be used. The coil may be formed from two separate sheets or from a single sheet bent double, the sheets may suitably be 1 to 2mm in thickness.

Both metal layers may be shaped, with complementary patterns so that when welded together they define a path or paths of refrigerant channels extending from an inlet to an outlet. The inlet and outlet are preferably provided adjacent one another and are preferably positioned at or adjacent one corner of the layers.

The refrigerant channel may be branched and may be provided in a wide variety of patterns.

The sheet metal layers forming the coil are preferably of elongate rectangular shape, and may be bent to form a square or rectangular shape for insertion into the tank. The refrigerant conduits making up the patterned channel may be of reduced cross section where they intersect lines along which the layers are bent.

When bent to fit within a chill tank, the condenser may be self-supporting and can simply sit on the bottom of the tank, avoiding the need for the fixings used to mount a conventional copper coil around the sides of the tank.

The sheet metal may suitably be provided with a polymeric coating for increased corrosion resistance.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings wherein: Figure 1 shows a refrigerant coil in accordance with the invention prior to bending into shape for insertion into a chill tank; Figure 2 is a perspective view of a chill tank positioned to receive the coil of Figure 1, bent into a square shape to fit the tank; Figure 3 is a schematic cross sectional view of the chill tank showing the refrigerant coil and beverage lines and the fluid flow within the ice bank; Figure 4 is a schematic view of a beverage coil for insertion into the chill tank of Figure 4; Figure 5 is a cross sectional view on the line v-v in Figure 1 and Figure 6 is a cross sectional view on the line vi-vi in Figure 1.

Referring first to Figures 1 and 2, a coil for use in accordance with the invention comprises two thin metal sheets 10, 20, preferably of aluminium, each being stamped with a pattern of channels 15, the cross sectional shape of which is shown in Figures 5 and 6. The channels preferably have a maximum width, in a direction transverse to the plane of the metal sheets of 2 to 5mm, typically about 3mm. Their maximum width (w in Figure 5) is preferably 8 to 15mm, except in the reduced sections or the bending lines as discussed below.

On each of the sheets the channels are formed as relatively shallow indentations with flat areas between them, and the opposing flat areas of the two sheets are welded together.

The sheets are preferably of aluminium, which is considerably cheaper than copper but nonetheless has the required high thermal conductivity and is relatively easy to shape and weld.

The outer surfaces of the sheets are coated with a thin later of a polymer such as an acrylic polymer for enhanced corrosion resistance.

The pattern of channels can be most clearly seen in Figure 1. These channels form an evaporator for a refrigeration circuit. From a refrigerant inlet 12, a single channel 14 passes from one end of the evaporator to the other, continuing with a reverse channel 17. The channels then form a serpentine path across the width of the evaporator and approximately three quarters of its length, dividing at 18 into a pair of parallel channels 22. At each reversal, there are provided short cross over channels such as 24 between the parallel channels, to ease the flow and reduce turbulence.

At the end of four such longitudinal runs, the parallel channels enter an end section 25 in which the two channels pass through a reverse loop 26 followed by a grid of channels 25. After emerging from this grid, the two channels rejoin one another at an outlet 28.

In Figure 2, the evaporator has been bent at right angles along lines A, B, C of Figure 1, to form a shape that is essentially square in plan view.

The sections 16 of the channels that cross these lines have a reduced cross section, as shown in Figure 6, to facilitate the bending. Here the transverse thickness may be the same but the maximum dimension w' is reduced, preferably to 5 to 10mm, typically 7.5mm. Bent to a square shape, the coil can be inserted into a chill tank 29, which may be of conventional design, with a water bath 30 and, underneath, the compressor and condenser of the refrigerant circuit.

The coil is dimensioned such that its width (or height as shown in Figure 2) is slightly less than the depth of the tank, so that the coil can simply sit on the bottom of the tank with a small gap between itself and the tank walls. With the coil made self supporting in this way, the fixings previously needed to secure a coil of copper pipe around the inner walls of the tank are no longer required.

Referring now to Figure 3, the tank 29 has insulated walls 33 surrounding the water bath 30. An insulated cover 42 is mounted over the water bath, and at the centre of the cover is mounted an electric motor 34 arranged to drive an impeller 38 and a propeller 35 mounted on a common shaft.

The coil 10, bent to its square shape as in Figure 2 and shown in cross section of Figure 3, sits on the bottom of the tank and does not require further support. A distance d between the coil and inner walls 32 of the tank is preferably 2 to 5 cm.

Beverage coils 50, also shown in cross section, are mounted within the tank spaced inwardly from the refrigerant coil. The beverage coil can be suspended from the cover 42 and connected to inlets and outlets mounted through the cover.

A typical beverage cooling coil 50 is shown in schematic side elevation in Figure 4, the coil is formed in a single plane and comprises an inlet 54 and outlet 56, both passing through the cover 42.

In operation, fluid refrigerant from a refrigerant circuit (not shown) is fed into the inlet 12 of the coil, passing through the coil to the outlet 28. The pattern of the coil, as shown in Figure 1, ensures that refrigerant is passing around all four sides of the tank.

The tank 30 is filled with water, and the electric motor 34 drives the propeller 35 and the impeller 38 in rotation so as to set up a toroidal flow of water as indicated by the arrows in the tank.

As the toroidal water flow passes down the inner sides of the coil 15, it starts to freeze and a wall of ice 40 builds up around the coil. As described in GB-A-2419176, it has been found that the water flow as shown in Figure 3, with water driven radially outwardly near the top of the tank and returning inwards at the bottom, flowing generally upwards at the centre of the tank and downwards along the ice bank, imparts an even shape to the ice bank, with essentially vertical walls and avoiding an inward build up of ice at the bottom of the tank.

As water flows through and around the beverage coils 50, beverages such as beer are fed through the coils before being conveyed to a dispensing point.

One or more of the coils 50 within the tank can be used, instead of cooling a beverage, to cool a liquid coolant such as methylene glycol, which can then circulate through its own line, parallel to the beverage line or lines, through a "python" to the dispensing point, thus keeping the beverage cool all the way to the dispensing point.

It has been found that use of a coil 15 in accordance with the invention allows considerable cost savings since it can be made of a cheaper material than copper and simply stood in the tank 30 without further fixings, and also reduces the amount of fluid refrigerant needed to cool a tank of given size.

Claims

CLAIMS1. A refrigerant coil for a chill tank comprising two layers of sheet metal bonded together, at least one of the layers being shaped so that the layers define between them one or more conduits for a refrigerant.
2. A refrigerant coil according to claim I wherein the layers of sheet metal are welded together.
3. A refrigerant coil according to claim I or claim 2 wherein the sheet metal is aluminium or an alloy thereof.
4. A refrigerant coil according to any preceding claim wherein both metal layers are shaped with complementary patterns so that when bonded together they define a path or paths of refrigerant channels.
5. A refrigerant channel according to any preceding claim wherein the conduit or conduits form a continuous path for refrigerant from an inlet to an outlet.
6. A refrigerant coil according to any preceding claim wherein the refrigerant conduit is branched.
7. A refrigerant coil according to any preceding claim wherein said sheet metal layers are bent into a self-supporting shape.
8. A refrigerant coil according to claim 7 wherein the sheet metal layers are of an elongate, substantially rectangular, shape and bent to form a free-standing coil, square or rectangular in plan view.
9. A refrigerant coil according to claim 7 or claim 8 wherein refrigerant conduits making up a patterned refrigerant channel are of reduced cross section where they intersect lines along which the metal layers are bent.
10. A refrigerant channel according to any preceding claim wherein the sheet metal layers are I to 2mm in thickness.
11. A refrigerant coil according to any preceding claim wherein the refrigerant conduits have a maximum width, in a direction transverse to the plane of the sheet metal layers, of 2 to 5mm.
12. A refrigerant coil according to any preceding claim wherein the refrigerant conduits have a maximum width, in a plane parallel to the sheet metal layers, of8to 15mm.
13. A beverage chill tank comprising a tank of liquid in which are immersed conduits for beverages to be cooled, a refrigerant coil in accordance with any preceding claim being immersed in said tank and having an inlet and an outlet for connection to a fluid refrigerant circuit.
14. A chill tank according to claim 13 wherein said refrigerant coil is free-standing and positioned around the inner walls of the tank to form an ice bank.Amendments to the claims have been filed as followsCLAIMS1. A refrigerant coil for a chill tank comprising two layers of sheet metal bonded together, at least one of the layers being shaped so that the layers define between them one or more conduits for a refrigerant, wherein said sheet metal layers are bent to stand on edge to form a free-standing self-supporting shape.2. A refrigerant coil according to claim I wherein the layers of sheet metal are welded together.3. A refrigerant coil according to claim I or claim 2 wherein the sheet metal is aluminium or an alloy thereof.4. A refrigerant coil according to any preceding claim wherein both metal layers are shaped with complementary patterns so that when bonded cy) together they define a path or paths of refrigerant channels.(\J 5. A refrigerant coil according to any preceding claim wherein the 0 conduit or conduits form a continuous path for refrigerant from an inlet to an outlet.6. A refrigerant coil according to any preceding claim wherein the refrigerant conduit is branched.7. A refrigerant coil according to any preceding claim wherein the sheet metal layers are of an elongate, substantially rectangular shape and bent to form a square or rectangular shape in plan view.8. A refrigerant coil according to claim 7 wherein refrigerant conduits making up a patterned refrigerant channel are of reduced cross section where they intersect lines along which the metal layers are bent.9. A refrigerant coil according to any preceding claim wherein the sheet metal layers are I to 2mm in thickness.10. A refrigerant coil according to any preceding claim wherein the refrigerant conduits have a maximum width, in a direction transverse to the plane of the sheet metal layers, of 2 to 5mm.11. A refrigerant coil according to any preceding claim wherein the refrigerant conduits have a maximum width, in a plane parallel to the sheet metal layers, of8to 15mm.12. A beverage chill tank comprising a tank of liquid in which are immersed conduits for beverages to be cooled, a refrigerant coil in accordance with any preceding claim being immersed in said tank and having an inlet and an (Y) outlet for connection to a fluid refrigerant circuit so as to form an evaporator of Q said circuit, wherein said refrigerant coil is positioned around the inner walls of the tank to form an ice bank.