GB2302403A - Apparatus for cooling liquids - Google Patents

Abstract

Apparatus for cooling liquids, typically potable liquids such as beer and water, comprises a pressure vessel (1) containing a multi-layer pipe coil (3) which is connected into a pipeline (5) so that beer held in a beer keg (6) and dispensed at a font (7) is caused to pass through the coil (3). The vessel (1) also contains a multi-layered pipe coil (2) which is connected to a conventional refrigeration system (8). The vessel (1) further contains a volatile fluid which forms a liquid body (4) and a vapour body (9) and the vessel (1) and the coils (2, 3) are so orientated that the product coil (3) lies in and is immersed in the liquid body whereas the refrigerant coil (2) lies in and is immersed in the vapour body (9). The apparatus may be used to cool water to such an extent that an icy slush is formed.

Description

APPARATUS FOR COOLING LIQUIDS This invention relates to apparatus for use in cooling liquids which are carried through a pipeline.

GB-A-2099979 discloses apparatus for cooling potable liquids such as beer, lager and the like. The apparatus is intended for use in establishments such as public houses, in which, for example, lager stored at ambient temperature in large volume kegs must be cooled before being dispensed from an appropriate font. The apparatus includes a pressure-tight vessel containing a volatile fluid which exists in a vapour phase and a liquid phase. In the lower portion of the vessel, and immersed in the liquid, is a helical "product" coil through which the beer passes as it flows from the keg to the font. A cooling coil forming part of a refrigeration system is located in the upper portion of the vessel in the vapour phase of the volatile fluid. Thus, as beer passes through the lower coil, and is cooled, the volatile liquid is heated and evaporates or vaporises.The cooling coil is simultaneously cooling and condensing the vapour, the condensed vapour flowing under gravity to cool and augment the liquid phase.

Due to its simplicity, reliability and efficiency, this apparatus has proved very popular since its introduction. However, the applicant has identified a number of improvements which may be made to the existing apparatus, and these are the subject of the present invention.

According to one aspect of the present invention there is provided apparatus for cooling liquids, the apparatus comprising means for confining a volatile fluid having liquid and vapour phases co-existing during operation of the apparatus and respectively forming a liquid body and a vapour body, a refrigeration system incorporating a cooling member, said member being immersed in the vapour body within said confining means, and a multi-layered product coil immersed in the liquid body within said confining means and through which the liquid to be cooled is passed.

In the existing apparatus the product coil is in the form of a helical coil lying on a horizontal axis.

Accordingly, the volume of the liquid body must be relatively large to completely immerse the coil, such that the confining means is relatively large. In this first aspect of the present invention the use of a multi-layered product coil allows both the dimensions of the confining means and the volume of the liquid body to be reduced. The reduction in volume of the liquid body reduces the thermal mass and decreases the response time of the apparatus. The use of a multi-layered coil also permits the use of longer coils of smaller diameter tubing to achieve a greater cooling effect: the longer coil increases the residence time of the liquid in the coil, and the increased turbulence in the smaller diameter tubing leads to a higher Reynolds number and better heat transfer coefficients across the tube wall.This advantage is particularly important when the apparatus is used for cooling soft drinks, which are dispensed relatively cold.

Preferably, the cooling member is in the form of a refrigerant coil, of a similar form to the product coil.

Two or more product coils may be provided and may be nested one within another, or may be arranged axially.

Preferably also, the product coil is vertically orientated. This results in an apparatus which is relatively insensitive to tilting. In the existing arrangement any significant degree of tilting may result in one end of the relatively long horizontally extending coil being exposed above the liquid body surface, thus reducing the cooling effect. Also, it is relatively straightforward to support compact vertically oriented coils to avoid the possibility of the refrigerant and product coils touching and freezing the liquid in the product coil.

Preferably also, any dead space within the product coil is occupied to further reduce the volume, and thus the thermal mass, of the liquid body.

Preferably also, the refrigeration system includes a compressor, heat rejection means such as a condenser, and a capillary tube for expanding the refrigerant prior to it passing into the cooling member, in the form of an evaporator. A valve is provided between the evaporator and the capillary tube with an actuator for opening the valve when the compressor is operational. Conveniently, the valve is a solenoid valve, and the solenoid is energised while the compressor is operating to allow circulation of refrigerant, but closes when the compressor shuts down to prevent flow of refrigerant from the high pressure side of the refrigeration system. In existing arrangements without the valve, refrigerant continues to "bleed" from the high pressure side through the capillary tube after the compressor cuts out.Without the continuous suction of the compressor this relatively warm fluid raises the temperature and pressure in the evaporator, such that the compressor is activated unnecessarily. The refrigerant system has a very low thermal mass such that the bleed through of refrigerant results in very rapid cycling of the compressor. Of course a similar valve may be provided in refrigeration systems for quite different applications and cooling systems.

The apparatus may include first and second means for confining a volatile fluid, with respective conduits providing fluid communication between the liquid bodies and vapour bodies within each means, a respective cooling member being immersed in each vapour body and a respective multi-layered coil being immersed in each liquid body and connected in parallel. Such an apparatus therefore includes two heat exchange "units" connected in parallel.

It has been found that linking two or more of such "basic" units in this manner is a convenient means for producing a higher rated cooling system.

The apparatus may be provided in series with other similar or identical apparatus, such that the cooled liquid from a first product coil is also passed through a second product coil in a further apparatus. This arrangement is particularly useful when it is desired to cool a liquid from a high inlet temperature to a low outlet temperature, for example cooling water from 350C to 20C; the "first stage" refrigeration unit for cooling the first stage cooling member may operate at a higher suction temperature which greatly improves the total system energy efficiency.

In accordance with another aspect of the present invention there is provided apparatus for cooling liquids, the apparatus comprising means for confining a volatile fluid having liquid and vapour phases co-existing during operation of the apparatus and respectively forming a liquid body and a vapour body, a refrigeration system incorporating an evaporator, said evaporator being immersed in the vapour body within said confining means, and a product conduit immersed in the liquid body within said confining means and through which the liquid to be cooled is passed, the refrigeration system further including a compressor, heat rejection means, a capillary tube for expanding the refrigerant prior to it passing into the evaporator, a refrigerant valve upstream of the evaporator, to isolate the evaporator from the high pressure part of the refrigeration system, and an actuator for opening the valve when the compressor is operational.

According to another aspect of the present invention there is provided a method of cooling water, the method comprising: confining a volatile liquid having liquid and vapour phases to provide a liquid body and a vapour body; immersing a cooling member in the vapour body; passing water through a conduit immersed in the liquid body such that the water is cooled by the liquid body to a temperature below the freezing temperature of the water; and collecting the water issuing from an end of the conduit, permitting ice crystals to form therein.

It has been found, most surprisingly, that it is possible to reduce the temperature of water flowing through the conduit to well below freezing (as low as - 2.00C in tests). Ice crystals do not begin to form until the water has been collected in a beaker or the like, and in a very short time the cooled water will form an icy slush in the beaker.

Advantageously, the method of this aspect of the invention is carried out utilising the apparatus of the first aspect of the invention as described above.

These and other aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of apparatus for cooling liquids in accordance with a preferred embodiment of the present invention; Figure 2 is a view from below of a first product coil of the apparatus of Figure 1; Figure 3 is a sectional view on line 3 - 3 of Figure 2; Figure 4 is a view from below of a second product coil which may be used with the apparatus of Figure 1; Figure 5 is a sectional view on line 5 - 5 of Figure 4; Figure 6 is a view from below of a third product coil which may be used with the apparatus of Figure 1; Figure 7 is a sectional view on line 7 - 7 of Figure 6; and Figure 8 is a schematic representation of apparatus for cooling liquids in accordance with another embodiment of the present invention.

Reference is first made to Figure 1 of the drawings, which illustrates, somewhat schematically, apparatus 10 for cooling beer in accordance with a preferred embodiment of the present invention. The apparatus 10 comprises a pressure-tight vessel 1 containing a multi-layered pipe coil 3 which is connected into a pipeline 5 so that beer held in a bulk container, in thin example a beer keg 6, and dispensed at a font 7 is caused to pass through the coil 3.

The vessel 1 also contains a multi-layered pipe coil 2 which is connected to a conventional refrigeration system 8. The vessel 1 further contains a volatile fluid which forms a liquid body 4 and a vapour body 9 and the vessel 1 and the coils 2, 3 are so orientated that the product coil 3 lies in and is immersed in the liquid body whereas the refrigerant coil 2 lies in and is immersed in the vapour body 9.

The refrigeration system 8 is substantially conventional, including a compressor, a condenser and a capillary tube, with the coil 2 forming the evaporator for the system. However, a solenoid valve 12 is provided upstream of the coil 2 and is activated to open to permit flow of refrigerant into the coil 2 only while the compressor is operating. This prevents flow of refrigerant from the high pressure side of the refrigeration system into the coil 2 when the compressor is not operating. In the absence of the closed valve 12 refrigerant would otherwise continue to bleed from the high pressure side of the system through the capillary tube. Without the continuous suction of the compressor this relatively warm fluid would raise the temperature and pressure in the coil 2, such that the compressor would be reactivated unnecessarily.With the relatively low thermal mass of the refrigeration system, such bleed through of refrigerant would result in very rapid cycling of the compressor.

In operation of the apparatus 10, the refrigeration system is actuated by an automatic control which may be either a switch sensitive to the vapour pressure within the vessel 1 or a switch sensitive of the temperature of the beer in the pipeline 5 (preferably on the font side of the vessel 1). Operation of the system 8 cools the refrigerant coil 2 causing vapour of the vapour body 9 to condense.

The condensed vapour flows under gravity to augment and cool the liquid body 4. Simultaneously, heat in the beer flowing along pipeline 5 causes the coil 3 to evaporate off or vaporise liquid from the liquid body 4, this vapour augmenting the vapour body 9. In consequence, the beer flowing in the coil 3 is cooled, and heat is removed from the apparatus by the refrigeration system 8.

Reference is now made to Figures 2 and 3 of the drawings which illustrate the product coil 3 in greater detail. The coil 3 is multi-layered and in this example comprises four radially spaced layers of tubing. The coil 3 is vertically orientated within the vessel 1. In use, this coil configuration permits the overall dimensions of the vessel 1 to be kept to a minimum, and also provides an apparatus which is relatively insensitive to tilting. The reduction in the dimensions of the vessel 1, and also the corresponding reduction in volume of the liquid body 4, reduce the thermal mass of the liquid body 4, thus reducing the response time of the apparatus 10. In the example illustrated in Figure 1 only a single product coil 3 is illustrated, and it will be noted that this results in "dead" space 14 within the lower portion of the vessel 1.

If desired, the lower wall of the vessel 1 may extend into this dead space 14, as illustrated in ghost outline in Figure 1, further reducing the volume of the liquid body 4.

The use of layer wound coils such as illustrated in Figures 2 and 3 also facilitates the provision of a plurality of product coils within the vessel 1, and further coil configurations are illustrated in Figures 4 and 5 and Figures 6 and 7 of the drawings. Reference is first made to Figures 4 and 5, which illustrate a second product coil 16 which is sized to nest within the larger first product coil 3. Thus, by providing a vessel 1 containing both coils 3, 16, it is possible for a single apparatus 10 to provide cooling for two different liquids, without any increase in external dimensions. In the illustrated examples the tubing forming the coils is 0.8 cm (5\16") outside diameter, the total length of the tubing of the coil 3 being 5.6 to 5.8 metres, whereas the length of the tubing in the smaller coil 16 is 1.77 to 1.85 metres long.

Reference is now made to Figures 6 and 7 of the drawings which show a third product coil 18 for location in the vessel 1 above or below the first product coil 3. The illustrated 0.8 cm (5\16") tubing coil 18 has a tubing length of approximately 1.5 metres.

The different coils 3, 16, 18 may be combined as desired for a particular application. In one example, the apparatus 10 may be utilised to dispense cool soft drinks comprising aerated water and an appropriate syrup. The aerated water which forms the bulk of the resulting drink is passed through the larger first coil 3, while the smaller syrup volume is passed through the appropriate smaller second or third coil 16, 18. Of course, additional coils may be provided, conveniently of similar diameter to the coils 3, 18, such that vessels 1 of similar diameter but different height may be provided for different applications.

Reference is now made to Figure 8 of the drawings which illustrates, somewhat schematically, apparatus 50 for cooling water in accordance with a further embodiment of the present invention. As with the apparatus 10 described above, the apparatus 50 comprises a pressure-tight vessel 51 containing a multi-layered pipe coil 53 which is connected into a pipeline 55 so that water from a storage tank 56 to be dispensed at a font 57 is caused to pass through the coil 53. The vessel 51 also contains a multilayered pipe coil 52 which is connected to a conventional refrigeration system 58. The vessel 51 further contains a volatile fluid which forms a liquid body 54 and a vapour body 59 in the vessel 51, and the coils 52, 53, are so orientated that the product coil 53 lies in and is immersed in the liquid body whereas the refrigerant coil 52 lies in and is immersed in the vapour body 59.

As is evident from Figure 8, the apparatus 50 of this embodiment differs from the apparatus 10 descried above in that two similar pressure vessels 51 are provided, each containing respective coils and fluid. The vessels 51 are linked by a vapour balance conduit 62 and a liquid balance conduit 64. Further, the pipeline 55 is connected in parallel to the inlets of the respective product coils 53, the outlets of the product coils 53 being connected in parallel with the font 57. Similarly, the respective refrigerant coils 52 are linked in parallel to the refrigeration system 58.

It has been found that providing units in parallel as illustrated in Figure 8 provides a convenient means for providing systems with a variety of different cooling capacities based on a single "basic" unit heat exchange.

It has also been found that the product coils of such single or parallel units may be connected in series with further single or parallel units, and such arrangements have found to be particularly useful when it is desired to cool a liquid from a high inlet temperature to a low outlet temperature.

In testing and use of systems in accordance with the invention it has also been found to be possible to provide outlet water of a temperature below the normal freezing point, and in which the water remains in liquid form until it has been collected at the outlet. This effect has been achieved using apparatus as illustrated in Figure 8 of the drawings. The apparatus 50 was provided with two product coils 53, each being 11.4 m long and of 8 mm outside diameter. Each refrigerant coil 52 was 10 metres long with an 8 mm outside diameter. The refrigerant coils 52 were connected to a 26 cc hermetic compressor\condenser set operating on refrigerant R22. The water flow in the line 55 was set at + 5eC and continuous circulation produced a water outlet temperature from the font 57 at -1\-20C. With this flow maintained, an accumulation of slush was produced in the collecting tank on a continuous basis. The water flowing from the font 57 was clear water in a metastable state, and ice crystals only began to form in the water once it had been collected in the tank 66.

It will be clear to those of skill in the art that the above-described embodiments are merely exemplary of the present invention, and that various modifications and improvements may be made thereto without departing from the scope of the invention.

Claims (12)

1. Apparatus for cooling liquids, the apparatus comprising means for confining a volatile fluid having liquid and vapour phases co-existing during operation of the apparatus and respectively forming a liquid body and a vapour body, a refrigeration system incorporating a cooling member, said member being immersed in the vapour body within said confining means, and a multi-layered product coil immersed in the liquid body within said confining means and through which the liquid to be cooled is passed.

2. The apparatus of claim 1 wherein the cooling member is in form of a multi-layered refrigerant coil.

3. The apparatus of claim 2 or claim 3 wherein two or more product coils are provided.

4. The apparatus of claim 3 wherein the product coils are nested one within another.

5. The apparatus of claim 3 wherein the product coils are arranged axially.

6. The apparatus of any of the preceding claims wherein the product coil is vertically orientated.

7. The apparatus of any of the preceding claims wherein any dead space within the product coil is occupied to reduce the volume of the liquid body.

8. The apparatus of any of the preceding claims wherein the refrigeration system includes a compressor, a heat rejection means, and a capillary tube for expanding the refrigerant prior to it passing into the cooling member, a valve being provided between the cooling member and the capillary tube with an actuator for opening the valve when the compressor is operational.

9. The apparatus of any of the preceding claims wherein the apparatus includes first and second means for confining a volatile fluid, with respective conduits providing fluid communication between the liquid bodies and vapour bodies within each means, a respective cooling member being immersed in each vapour body and a respective multi-layered coil being immersed in each liquid body and being connected in parallel.

10. The apparatus of any of the preceding claims wherein the apparatus is provided together with another similar or identical apparatus, and a first product coil of one apparatus is connected in series with a second product coil of the other apparatus.

11. Apparatus for cooling liquids, the apparatus comprising means for confining a volatile fluid having liquid and vapour phases co-existing during operation of the apparatus and respectively forming a liquid body and vapour body, a refrigeration system incorporating an evaporator, said evaporator being immersed in the vapour body within said confining means, and a product conduit immersed in the liquid body within said confining means and through which the liquid to be cooled is passed, the refrigeration system further including a compressor, heat rejection means, means for expanding the refrigerant prior to it passing into the evaporator, a refrigerant valve upstream of the evaporator, to isolate the evaporator from the high pressure part of the refrigeration system, and an actuator for opening the valve when the compressor is operational.

12. A method of cooling water, the method comprising: confining a volatile liquid having liquid and vapour phases to provide a liquid body and a vapour body; immersing a cooling member in the vapour body; passing water through a conduit immersed in the vapour body such that the water is cooled by the liquid body to a temperature below the expected freezing temperature of the water; and collecting the water issuing from the end of the conduit, which water then forms an icy slush.