GB2419176A

GB2419176A - A device for cooling liquids

Info

Publication number: GB2419176A
Application number: GB0423095A
Authority: GB
Inventors: Michael John Filmer
Original assignee: MF REFRIGERATION Ltd
Current assignee: MF REFRIGERATION Ltd
Priority date: 2004-10-18
Filing date: 2004-10-18
Publication date: 2006-04-19
Anticipated expiration: 2024-10-18
Also published as: GB2419176B; GB0423095D0

Abstract

An ice bank cooler comprising a tank filled with water, refrigerant coils (12, Fig 1) adjacent to the inner walls of the container arranged to form an ice bank (40, 42), beverage cooling coils (16, Fig 1), a python through which cooled water is circulated from the tank, and a motor (23, Fig 1) which drives in rotation an impeller (38) and a propeller (35) mounted on a shaft projecting downwardly into a central part of the tank, to circulate the water in the tank in a toroidal flow. The propeller (35) causes water to pass upwardly through a central part of the tank, and the impeller (38) causes water to flow radially outwardly when it reaches an upper part of the tank and downwardly over the surface of the ice bank. This prevents the disproportionate build-up of ice at the bottom of the ice bank and promotes even thickness of ice on the refrigerant coils and homogeneity of water temperature with a resulting increase in beverage cooling efficiency.

Description

COOLING DEVICE

This invention relates to a device for cooling liquids, for example draft beer or other beverages passing along a conduit on their way from a supply container to a serving point.

A well known device commonly used for cooling draft beer and other beverages comprises a tank which is filled with water and in which one or more refrigerant coils are arranged to form an ice bank, usually adjacent the inner walls of the container. The refrigerant coil forms an evaporator surface, and a refrigeration circuit is operated so that refrigerant is circulated through the coil, causing the water adjacent to the coils to freeze and thus building up a bank of ice on the coil. The ice bank generally extends from the inner walls of the tank to enclose the refrigerant coil, chilling the water in the tank to a temperature close to 0 C.

Submerged in the water bath is a plurality of beverage cooling coils, through which beer and the like may be passed and thus cooled. Also submerged in the tank is a pipe through which cooled water is circulated from the tank, forming, together with the beverage lines, a sheathed bundle of pipes known as a "python", running from the cooling tank to the bar or other point of service, the water pipe then returning to the tank. A pump located just above the tank circulates the chilled water through the python. - 2 -

In order to assist chilling of the beverage passing through the cooling conduits in the tank, the pump is typically also arranged to drive a shaft extending downwardly into the tank with a propeller at its lower end to cause the water in the tank to circulate in a toroidal flow, passing through the cooling ducts and over the surface of the ice bank.

Typically, the driven shaft extends vertically down in the centre of the tank and drives water downwardly to the bottom of the tank so that it forms a toroidal flow, outwardly across the bottom of the tank and back up over the surface of the ice bank. A system of this type is illustrated in Fig. 1 of the accompanying drawings and will be described in more detail below.

The purpose of circulating the water by means of the propeller is to give a homogeneous water temperature which gradually approaches the temperature at which it freezes.

This is important in maintaining a constant dispensing temperature for a particular beverage which passes through the cooling ducts within the tank. Sensors are usually employed so as to switch off the refrigeration circuit when a predetermined thickness of ice has been achieved, and to switch it on again when the ice bank shrinks to less than a specified thickness.

One problem which arises with such a system is that the toroidal flow generated by agitation of the water within the tank can cause differential erosion of the ice bank in the lower part of the tank. Water flowing outwards over the bottom of the tank impacts with some - 3 - force on the bottom of the ice bank and then flows upwardly over the ice bank, but the flow tends to turn inwards again higher up, so that the ice bank becomes thicker at the top than at the bottom. This is problematic in that the water is no longer circulating along the entire surface of the ice bank, which adversely affects the homogeneity of water temperature and the heat transfer efficiency between the beverage coils and the water in the tank. A further problem is that probes or other sensors measuring the ice bank thickness may be detecting significant thickness of ice, when the substantial build-up of ice is present only on a limited number of coils near the top of the tank and absent on those near the bottom.

Various solutions have been proposed to prevent the uneven erosion of the ice bank. For example, in EP-A-1055889, the pump housing extends below the surface of water in the tank and has a plurality of circumferentially spaced apart outlets through which streams of water are directed towards the ice in the upper region of the cooling coil, in order to promote an even thickness of ice on the cooling coil.

In GB-A-2343243, the refrigerant coils are wound closer to one another at the bottom of the tank than at the top, the closer spacing of the coils resulting in faster ice formation at the bottom of the ice bank than at the top, to compensate for the increased ice bank erosion in the lower part of the tank. 4 -

In WO02/084188, a baffle or other deflector is positioned on the bottom of the tank so as to direct water upwardly just before it reaches the ice bank, so as to promote an even flow over the surface of the ice bank.

It is an object of the invention to provide an ice bank cooler of simplified construction and improved performance, and in particular to prevent erosion of the ice bank, resulting in improved heat exchange between the water in the tank and the ice bank, with a resulting increase in beverage cooling efficiency.

According to the present invention there is provided an ice bank cooler comprising a water tank, refrigerant means positioned adjacent at least one side wall of the water tank and an agitator located in the tank to cause water to circulate in the tank and to pass over or adjacent the refrigerant means to promote heat exchange between the water and an ice bank formed on the refrigerant means, wherein the agitator is arranged to circulate the water in a toroidal flow, passing upwardly through a central part of the tank, flowing radially outwardly when it reaches an upper part of the tank and downwardly over the surface of the ice bank.

The refrigeration means preferably comprises one or more refrigerant coils mounted on the inner walls of the tank so that in use substantially the whole of the tank inner walls are covered by ice banks.

The agitator is preferably in the form of a propeller mounted on a shaft projecting downwardly into a central part of the tank and driven by a motor which preferably also drives a pump to circulate water from the tank through a cooling "python" or the like, as disclosed for example in EP-A-1055889. However, the agitator of the present invention differs from that of EP-A-1055889 in that its pitch is reversed so as to draw water upwardly from a central part of the bottom of the tank, rather than driving it downwards and outwards to erode the bottom of the ice bank. Because water is not being driven hard against the bottom of the tank, it does not flow outwards with the same force as in a conventional cooler, but forms a more even toroidal flow, flowing radially outwardly near the top of the tank and then downwards over substantially the whole surface of the ice bank. In doing so, the water preferably passes through cooling conduits containing liquids to be cooled, for example beverages such as draft beer.

An impeller is preferably positioned on the shaft above the reverse pitch propeller, to encourage the radially outward flow of water near the top of the tank.

The reverse pitch propeller and impeller may be retrofitted to any of the standard pumps employed in conventional ice bank coolers.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings wherein: FIG. 1 is a schematic vertical cross-section through an ice bank cooler of conventional design; - 6 FIG. 2 is a schematic vertical cross-section through an ice bank cooler according to the present invention; and FIG. 3 is a schematic side elevation of a beverage coolant coil of a type which may be used in the coolers of the present invention.

Referring first to Fig. 1, a conventional beer cooler comprises a tank 10 which is generally square or rectangular in plan view and has bottom and side walls which are thermally insulated. It is filled with water 14 in which are immersed cooling coils 16 through which is passed a beverage such as draft beer to be cooled.

Around the inner walls of the tank are refrigerant pipes 12, which may suitably be provided in the form of a single coil fixedly mounted within the tank, spaced a short distance from the inner sides. As refrigerant is passed through the pipes 12, an ice bank 20 forms around the side of the tank.

A pump 22, driven by a motor 23, is provided to draw water from the tank, via an outlet pipe 25, to run along a "python", in an insulated sheath with pipes connected to cooling coils 16, to keep the beer cool as it runs to its delivery point. The water then runs back through an inlet pipe 27.

The motor 23 also drives in rotation a shaft 24 which extends vertically down into a central part of the tank.

On the end of the shaft is mounted a propeller 26 which, when driven in rotation, drives water downwards in the - 7 direction of the arrows to the bottom of the tank, whereby the water circulates in a toroidal flow.

As shown in Fig. 1, water being driven along the bottom of the tank impinges on the bottom 28 of the ice bank 20 and tends to erode this part of the ice bank so that it is thinner at this point than further up. As the water rises, passing over the surface of the ice bank, the moving water tends to drift inwards away from the ice bank. The net effect is that there is a build-up of ice around the top of the ice bank, so that both water circulation and cooling become uneven.

Sensors (not shown) are provided to detect the thickness of the ice bank, and to stop the circulation of refrigerant when a predetermined thickness is reached. If the build-up of ice is uneven, the accuracy of the sensors may be adversely affected, causing them to detect a volume of ice greater than is actually present and to cut of the circulation of refrigerant prematurely.

In the embodiment of Fig. 2, according to the invention, the propeller 26 is replaced with a propeller of opposite pitch. When driven in the same direction as in Fig. 1, this propeller instead draws water up from the bottom of the tank, reversing the toroidal flow.

Also mounted on the shaft 24, above the propeller 35, is an impeller 38 which tends to drive the water radially outwardly, causing it to flow between the beverage cooling coils 16 and downwardly over the surface of the ice bank. - 8 -

Because the water reaching the upper end 42 of the ice bank has not impacted on a solid surface such as the tank bottom, it does not impact with such force on the ice bank and does not therefore erode it as the bottom of the bank in Fig. 1. Instead the water flows smoothly over the surface of the ice bank until it reaches the bottom of the tank when it is turned sharply away. Water thus flows evenly over the ice bank surface, right down to the bottom, preventing any build-up of ice at the bottom edge of the ice bank.

With the device of the invention therefore, an ice bank can develop which is of uniform thickness from top to bottom and thus uniformly spaced from the beverage cooling coils. Heat exchange is thus uniform throughout and any uneven build-up of ice, which can be disruptive and lead to the apparatus having to be switched off and de-iced, is prevented.

Referring to Fig. 3, one of the beverage cooling coils 16 shown in Figs. 1 and 2 is shown here in a schematic side elevation. The cooling coil is mounted on a transverse bar 52 which rests across the top of the tank and has an inlet line 54 which coils inwardly to the middle, then reverses and coils outwardly again to an outlet 56.

It will be seen that the reverse propeller 35 and impeller 38 can be retrofitted on to the shaft of an existing pump, for insertion into an existing beer cooler.

Claims

1. An ice bank cooler comprising a water tank, refrigerant means positioned adjacent at least one side wall of the water tank and an agitator located in the tank to cause water to circulate in the tank and to pass over or adjacent the refrigerant means to promote heat exchange between the water and an ice bank formed on the refrigerant means, wherein the agitator is arranged to circulate the water in a toroidal flow, wherein the agitator causes the water to pass upwardly through a central part of the tank and to flow radially outwardly when it reaches an upper part of the tank and downwardly over the surface of the ice bank.

2. An ice bank cooler according to claim 1, wherein the refrigerant means comprises one or more refrigerant coils mounted on the inner walls of the tank so that in use substantially the whole of the tank inner walls are covered by ice banks.

3. An ice bank cooler according to any preceding claim, wherein the agitator is in the form of a propeller mounted on a shaft.

4. An ice bank cooler according to claim 3, wherein said propeller projects downwardly into a central part of the tank and has a pitch arranged to draw water upwardly from a central part of the bottom of the tank.

5. An ice bank cooler according to claim 3 or claim 4, wherein said propeller is driven by a motor which also drives a pump to circulate water from the tank through a cooling "python" or the like outside the tank. lO

6. An ice bank cooler according to any preceding claim, wherein an impeller is positioned on the shaft above the propeller to encourage the radially outward flow of water near the top of the tank.

7. An ice bank cooler according to any preceding claim, wherein the propeller is retrofitted to a pump of an existing ice bank cooler.

8. An ice bank cooler substantially as herein described with reference to and as illustrated in Figure 2 of the accompanying drawings.