Liquid cooler

Abstract

 A liquid cooler comprises a tank (1) for receiving liquid to be cooled and an evaporator tube (2) in the form of a coil in the tank (1).
In order to enable the liquid in the tank to be used directly, the evaporator tube (2) comprises an inner tube (4) for refrigerant and an outer tube (3) surrounding the inner tube (4) and of a material having no adverse effect on the liquid.

Description

[0001] This invention relates to liquid coolers.

[0002] It is often desired to provide cold or chilled drinks and this creates particular problems where the drinks are being served by automatic vending machines. In the past, so-called "on line" cooling has been used extensively whereby water for making the soft drinks passes through a cooling coil in a water bath, the bath itself being cooled by the use of a copper evaporator coil, connected to a refriferating unit. While such an arrangement is quite satisfactory and has been used for some years for cooling beer, its use in vending machines is nevertheless quite expensive particularly because of the necessity of providing a cold water bath for periods when no drinks are being bought and due to necessity of providing a break-tank from which the drinking water is supplied since regulations do not permit the water used in the vending machine to be supplied directly from the mains so as to prevent contamination of the mains.

[0003] The present invention seeks.to simplify the cooling of liquids as compared to known methods and at the same time provide a reduction in cost of the necessary parts.

[0004] According to the invention, there is provided a liquid cooler comprising a tank for receiving liquid to be cooled and an evaporator tube in the form of a coil in the tank characterised in that the evaporator tube comprises an inner tube for refrigerant and an outer tube surrounding the inner tube (4) and of a material having no adverse effect on the liquid.

[0005] Preferably the inner refrigerant tube comprises copper and the outer tube comprises stainless steel.

[0006] Where the liquid is to be cooled is water, and is for use in a vending machine, the tank containing the liquid may also act as a break-tank, thus dispensing with the need for having a separate break-tank.

[0007] As a result of these measures, the tank can provide a supply of chilled liquid which can be maintained in the chilled state at all times, thus reducing the amount of refrigeration necessary as compared to an on line system with a consequent reduction in the size of the refrigerating plant, in particular the use of a smaller compressor. Furthermore the length of the coil in the tank can be considerably reduced as compared to the individual coils which were necessary in the on line system.

[0008] Suitably the outer stainless steel tube is a welded tube whereas the copper inner tube is a drawn tube.

[0009] The invention will now be described in greater detail, by way of example, with refgerence to the drawings in which:-

Figure 1 is a diagrammatic plan view of the lay-out of a break-tank for cool'ing water for a vending machine, and

Figure 2 is a part sectional view taken on the line II-II of Figure 1 showing the arrangement of the two tubes provided in the coil in the tank of Figure 1.

[0010] Figure 1 shows a break-tank 1 for which the supply or inlet of liquid i.e. water is only shown diagrammatically at 10, the supply of water to the tank being controlled, e.g. by a float operated valve or a solenoid operated valve which supplies water from the mains. The tank 1 itself is suitably rectangular and within the tank 1 there is provided a cooling coil 2 which runs round the inside of the tank leaving the bottom and top clear. The cooling coil 2 comprises an outer stainless steel tube 3 produced in known manner from stainless steel (strip) bent and longitudinally welded and an inner drawn copper tube 4 which extends through the length of outer tube 3 and in which a refrigerant medium flows. Outlet of liquid from the tank 1 is shown diagrammatically as an output connection 11 in the bottom of the tank 1.

[0011] As can be seen particularly from Figure 2, the stainless steel tube extends out of the water 5 in the tank at both ends 12 and 13 and is soldered to the inner copper tube 4 at 6 in a position well clear of the water. The copper tube 4 in turn is soldered at both ends to the piping 7 of the refrigerating system at 8.

[0012] In this way the water in the tank can be cooled down to provide an overall chilled temperature by means of the coil 2 and can be maintained substantially at this temperature indefinitely with little expenditure on refrigeration. surfaces coming into contact with the water are of stainless steel which prevents any contamination of the water in the tank by the material of the refrigerant coil. The inner coil 4 within the coil 3 carries the refrigerating medium and thus a double skin protection is provided for prevention of contamination of the water by the refrigerant. This is the same amount of protection as is normally afforded by the on-line system.

[0013] As has been previously stated, because of the provision of a permanently chilled volume of water, there is no need to provide a separate break-tank nor is it necessary to have high power refrigerating compressor since the amount of refigeration necssary depends on the temperature of the water in the tank and not on the speed at which the liquid passes through a coil as in the on-line system. Thus even the coils can be smaller than in the previous on-line system.

[0014] In a particular example, a 5/16in (7.94mm) outside diameter stainless steel tube having a 1/4in (6.35mm) bore was used for the outside coil. The inner coil was a drawn copper tube of 6mm outside diameter and 0.6mm wall thickness. In order to construct the coil, the inner copper tube is inserted into the outer stainless steel tube with both tubes straight and the tubes are then wound together in a coil winder. The necessary length of the coil in this example was 18 1/2ft (5.64M) whereas an on line cooler required a refrigerating coil of a length between 10 and 7.5M and a drinking water tube of 20ft (6.1M).

[0015] It will be appreciated that various modifications may be made to the above described embodiment without departing from the scope of the invention. For example, the stainless steel tube could also be drawn. While the stainless steel tube is stated as being soldered to the copper tube, if desired the stainless steel tube could remain open at the ends and in this way any significant leakage of refrigerant from the copper tube would become apparent. The invention is not limited to use in vending machines but can be usd for cooling of drinking liquids where such are required to be stored.

Claims

1. A liquid cooler comprising a tank (1) for receiving liquid to be cooled and an evaporator tube (2) in the form of a coil in the tank (1), characterised in that the evaporator tube (2) comprises an inner tube (4) for refrigerant and an outer tube (3) surrounding the inner tube (4) and of a material having no adverse effect on the liquid.

2. A liquid cooler as claimed in claim 1, wherein the inner refrigerant tube comprises copper and the outer tube comprises stainless steel.

3. A liquid cooler as claimed in claim 2 wherein the liquid to be cooled is water and the tank (1) comprises a break-tank.

4. A liquid cooler as claimed in claim 2 or 3, wherein the copper tube (4) is drawn and the stainless steel tube (3) is welded.

5. A liquid cooler as claimed in claim 2,3 or 4 wherein the stainless steel tube (3) surrounds the copper tube (4) over the region in which the liquid to be cooled could have access.

6. A liquid cooler as claimed in any one of claims 2 to 5, wherein the stainless steel tube (3) is sealed to the copper tube (4) at its ends.

7. A liquid cooler as claimed in any one of claims 2 to 5, wherein the ends of the stainless steel tube (3) are left open to provide access to the space between the two tubes (3,4).

Drawing