Cooling Apparatus

This invention relates to a cooling apparatus. In. particular, this invention relates to a cooling apparatus for cooling a product, such as a beverage, by heat transfer between the product and a cooling liquid formed by the mixing of a solid and a liquid reactant.

It is generally accepted that products such as beverages e.g. beer, lager, cider and soft drinks should be served chilled and refrigeration systems are usually provided in public houses and restaurants for effecting such cooling. Furthermore, kegs/cans/bottles of such a beverage for home consumption are usually stored in a domestic refrigerator prior to consumption.

One problem is that there may be insufficient space in a user's domestic refrigerator to cool a keg or the required number of beverage cans/bottles.

In some cases, rapid cooling of a beverage is required, for example in cases of unplanned consumption. The time taken for beverage cooling in a domestic refrigerator is often significantly longer than a consumer would want. For example, cooling a keg takes around 12 hours in a domestic refrigerator.

Further problems arise when a consumer wishes to consume such a beverage at a location where no refrigeration system is available. For example, a consumer may wish to take cans/bottles of beverage on a picnic, barbeque or to a sporting event at which no electricity is available and thus no electrically powered refrigeration system is available.

In this case, it is known to first cool cans/bottles in a refrigerator and then transport them to and store them at the desired location in an Esky™ which is a portable cooler in which frozen ice packs are placed along with the cans/bottles to keep them cool. Of course, such a cooler only works for as long as the ice packs remain frozen and the cooling will gradually decrease in effectiveness as time passes. Therefore, after some time, the beverage is no longer sufficiently cooled for the consumer's taste.

It is known from US 4607502 to cool beverages using the endothermic interaction between water and a solid reactant. This has the advantage that maximum cooling can be applied just before the beverage is desired rather than at the time the beverage is first removed from the refrigerator. In US 4607502, the solid reactant is provided in a wrapping which extends around an array of beverage containers. Water is added to the solid reactant and the containers are cooled by heat transfer with the refrigerating mixture in the wrapping.

The inventors of the present invention have discovered that the effectiveness and speed of cooling relies on the efficient mixing of the solid and liquid reactants (to achieve rapid dissolution of the solid reactant in the liquid reactant) and the extent of heat transfer from the beverage containers. Further more, they have found that efficient mixing can be achieved without mechanical agitation. A preferred aim of the present invention is to improve the mixing of the solid and liquid reactants and/or to improve the heat transfer from the product to achieve improved product cooling.

Accordingly, in a first aspect, the present invention provides an apparatus for cooling a product, the apparatus comprising: a reaction chamber for containing a solid reactant and having a base; an inlet for the introduction of a liquid reactant into the reaction chamber; and at least one perforated support which, in use, suspends the solid reactant above the reaction chamber base to facilitate dissolution of the solid reactant in the liquid reactant to form a cooling liquid in the reaction chamber; wherein, in use, the product is cooled by heat transfer between the product and the cooling liquid in the reaction chamber.

By providing at least one perforated support for suspending the solid reactant above the reaction chamber base, a space is created (at least during use) between the perforated support and the reaction chamber base in which, when filled with sufficient liquid reactant, free convection flow can occur to aid dissolution of the solid reactant in the liquid reactant.

Liquid reactant introduced into the reaction chamber can infiltrate the solid reactant on the perforated support through the perforations. Where the solid reactant is infiltrated by the liquid reactant, dissolution of the solid reactant occurs to form a cooling liquid which is colder and more saturated and therefore more dense than the

liquid reactant. The cooling liquid sinks to the base of the reaction chamber. As the cooling liquid sinks, warmer and less dense unsaturated liquid reactant will rise to take its place and will come into contact with the un-dissolved solid reactant, the un- dissolved solid reactant having fallen towards the perforated support to take the place of the dissolved solid reactant. This free convection flow (i.e. the sinking of cooling liquid and rising of liquid reactant) will continue until all of the solid reactant has dissolved in the liquid reactant (or the liquid reactant has become saturated) to form the cooling liquid. The free convection flow results in complete and thorough mixing of the reactants without mechanical agitation (i.e. the reactants are "self- stirred") leading to a more effective and rapid cooling of the product.

Preferably, the at least one perforated support is adapted so that, in use, it suspends the solid reactant at or near the liquid reactant/air interface within the reaction chamber (i.e. at or near the uppermost level of the liquid reactant). The at least one perforated support may be adapted so that, in use, the liquid reactant/air interface substantially corresponds to the solid reactant/air interface or the at least one perforated support may be adapted so that, in use, the liquid reactant/air interface lies within the mass of solid reactant.

By suspending the solid reactant at or near the liquid reactant/air interface, preferably with the liquid reactant/air interface substantially corresponding to the solid reactant/air interface or the liquid reactant/air interface lying within the solid reactant, an advantageous balance between the liquid reactant penetration of the solid reactant and the volume of the space between the perforated support and the reaction chamber base in which convection flow can occur is achieved. This arrangement also ensures that, in use, there is no liquid reactant above the solid reactant; free convection flow cannot occur in any liquid reactant lying above the solid reactant. As a result, the maximum dissolution rate is possible.

The at least one perforated support may be fixed within the reaction chamber so as to suspend the solid reactant at a fixed height above the reaction chamber base, the preferred fixed height being selected so that, in use, the solid reactant is suspended at or near the liquid reactant/air interface obtained when the maximum desired amount of liquid reactant has been added, preferably with the liquid reactant/air interface substantially corresponding to the solid reactant/air interface or

the liquid reactant/air interface lying within the solid reactant for the reasons described above.

Alternatively, the at least one perforated support may be movable within the reaction chamber i.e. it may be movable relative to the reaction chamber base to vary the distance between the perforated support and the reaction chamber base.

Preferably, the or each perforated support is provided with at least one float so that the height at which the solid reactant is suspended from the reaction chamber base increases as liquid reactant is introduced into the inlet. Preferably, the buoyancy of the at least one float is selected so that, in use the solid reactant is suspended at or near the liquid reactant/air interface, preferably with the liquid reactant/air interface substantially corresponding to the solid reactant/air interface or the liquid reactant/air interface lying within the solid reactant.

Alternatively, the apparatus may be provided with mechanical means for moving the or each perforated support. The mechanical means include a spring and a variable suspension device

By providing a perforated support which is vertically movable relative to the reaction chamber base, it is possible to ensure that solid reactant is suspended within the reaction chamber at or near the uppermost level of the liquid reactant at all times. Furthermore, it is possible for dissolution of the solid reactant to commence as soon as the introduction of liquid reactant into the inlet is commenced.

Preferably there is a single perforated support which may be dimensioned to fit the horizontal cross section of the reaction chamber. The perforated support may be a gauze, mesh, grill or grate.

There may a single float which is donut-shaped. A single perforated support is preferably provided, dimensioned to fit the central hole of the donut-shaped float. Alternatively, the single perforated support may be donut-shaped with a single float dimensioned to fit the central hole of the perforated support.

Preferably, the apparatus includes at least one product holder for holding the product in thermal contact with the reaction chamber. By holding the product in thermal contact with the reaction chamber, more effective heat transfer can occur.

Rapid cooling is possible e.g. cooling of beverage from room temperature to a desirable drinking temperature (around 4 ⁰ C) can be achieved in around 30 minutes using the apparatus of the present invention.

The product can be any product requiring cooling. It may be a liquid product e.g. a beverage or a solid product e.g. a food item. Preferably the product is a beverage.

The reaction chamber is defined by a chamber wall and the chamber wall adjacent the product holder will be at least partially thermally conductive.

The product holder(s) may be defined by holder walls and the holder wall adjacent the reaction chamber will be at least partially thermally conductive. The holder walls which are not adjacent the reaction chamber are preferably formed of insulating material.

In other embodiments, the product holder(s) may be at least partially defined by the reaction chamber wall, i.e. there may be at least one common wall between the reaction chamber and the product holder(s). This will allow maximum heat transfer between the product and the cooling liquid. Most preferably, the product holder is partly defined by the reaction chamber walls and partly defined by insulating material.

The product holder may surround the reaction chamber. For example, the reaction chamber may be a substantially cylindrical chamber and the product holder may be an annular chamber surrounding the reaction chamber. In this case, the inner wall of the product holder may be defined by the outer (thermally conductive) wall of the reaction chamber, or it may be a separate, thermally conductive wall. Preferably, the outer wall of the product holder is defined by an insulating material. Providing the product holder surrounding the reaction chamber ensures that a high degree of thermal contact between the reaction chamber and the product is achieved.

Alternatively, there may be one or more product holders located adjacent the reaction chamber walls but not completely encircling the reaction chamber. For example, the reaction chamber may be a cube or a cuboid with a product holder provided adjacent one or more (preferably two) of the cube/cuboid faces. Alternatively, one or more product holders may be located adjacent the reaction chamber wall defining the base of the reaction chamber i.e. the one or more product holders may be adjacent (below) the base of the reaction chamber. In this way, free convection flow within a liquid product, e.g. beverage, can be established i.e. beverage adjacent the reaction chamber will be cooled and will sink within the product holder (or within a can/keg/bottle housed in the product holder) with warmer beverage rising within the product holder (or within a can/keg/bottle housed in the product holder). In these embodiments, one face of the one or more product holders may be defined by either a (thermally conductive) wall of the reaction chamber or a separate, thermally conductive holder wall.

In another alternative, the reaction chamber may surround at least one product holder. For example, the product holder may be a substantially cylindrical chamber and the reaction chamber may be an annular chamber surrounding the at least one product holder. The product holder and reaction chamber may share a common, thermally conductive wall. Again, this ensures that a high degree of thermal contact between the reaction chamber and the product is achieved. Preferably, there is a plurality of product holders, each holder extending within and surrounded by the reaction chamber. In embodiments where there is at least one product holder in the interior of the reaction chamber, a layer of insulation is preferably provided around the outside of the reaction chamber.

The product holder(s) may be adapted to contain a liquid product, e.g. beverage, per se (in which case it/they will include a liquid product inlet/outlet) or it/they may be adapted to house a liquid product, e.g. beverage, in containers such as bottles/cans. Preferably, the product holder(s) is/are sized to receive bottles/cans, for example, in a vertical stack or horizontal array. If a product holder is adapted to contain liquid product e.g. beverage containers, e.g. cans in a vertical stack, or a solid product, an ejection mechanism e.g. a spring is preferably provided to allow access to the containers/solid product which are not initially accessible.

Preferably, the cooling apparatus further includes means for preventing removal of the cooling liquid from the reaction chamber by the user. This may be a one-way valve fitted at the inlet. Furthermore, as the liquid reactant e.g. water is poured into the reaction chamber through the inlet, there is a chance that splash back may occur which is inconvenient for the user and may expose the user to the hazardous cooling liquid. The provision of a one-way valve reduces the chance of exposure of the user to the cooling liquid.

The solid reactant can be any solid capable of forming a cooling liquid upon mixing with a liquid reactant. The liquid reactant is preferably water and the solid reactant is or includes a salt such as ammonium nitrate. The solid reactant may be, for example, a mixture of ammonium nitrate and calcium carbonate. The solid reactant is preferably in the form of prills which are easily handled and which will not generate dust. Furthermore, prills have a large surface area/mass ratio and thus will readily dissolve in the liquid reactant.

The apparatus is preferably provided with insulation to prevent heat exchange between the cooling liquid in the reaction chamber and the environment.

Preferred embodiments of the present invention will be illustrated in the following Figures in which:

Figures 1 and 2 show a vertical cross section through a first preferred embodiment of the present invention; and

Figure 3 shows a vertical cross section through a second preferred embodiment of the present invention.

Figure 1 shows a cooling apparatus comprising a substantially cylindrical reaction chamber 1 defined by chamber walls 2 which are formed of a thermally conductive material such as aluminium. An inlet 3 is provided in the top of the chamber to allow the introduction of a liquid reactant such as water. A one way valve is provided (not shown) at the inlet 3 to prevent removal of the cooling liquid by the user. A perforated support plate 4 formed of gauze is provided and is spaced from the reaction chamber base 5.

The product holder 6 is a chamber surrounding the reaction chamber. The holder is defined by holder walls 7 but could simply be defined by the reaction

chamber wall 2 and insulation 8. In the embodiment shown in Figure 1 , the product holder is adapted to hold beverage per se. There is an inlet (not shown) into which beverage can be poured and an outlet (not shown) from which beverage can be dispensed after cooling. Alternatively, the product holder could be adapted to hold beverage containers e.g. beer cans. For example, the product holder could be dimensioned to hold a vertical stack of beer cans extending around the perimeter of the reaction chamber.

As shown in Figure 2, in use, beverage or beverage containers are provided in the product holder 6 and solid reactant 9 (ammonium nitrate prills) is provided in the reaction chamber 1 suspended from the reaction chamber base 5 by the perforated support plate 4. When cooling of the beverage is desired, a liquid reactant

(water) is added to the reaction chamber through the inlet 3. Water is added until the water/air interface 10 within the reaction chamber lies within the bulk of the solid reactant 9. In the area of overlap between the solid reactant 9 and the water, dissolution of the solid reactant occurs to form a cold/saturated and therefore dense cooling liquid. The cooling liquid sinks to the reaction chamber base 5 and this sets up a free convention flow as shown by the arrows in Figure 2. The free convection flow aids efficient mixing of the reactants resulting in rapid dissolution of the solid reactant.

Figure 3 shows a cooling apparatus comprising a substantially cylindrical reaction chamber 1 defined by chamber walls 2 which are formed of a thermally conductive material such as aluminium. An inlet 3 is provided in the top of the chamber to allow the introduction of a liquid reactant such as water. A one way valve is provided (not shown) at the inlet 3 to prevent removal of the cooling liquid by the user. A perforated support plate 4 formed of gauze is provided and is spaced from the reaction chamber base 5. The perforated support plate is carried by a donut- shaped float 11 formed of polystyrene. The perforated support plate is vertically moveable within the reaction chamber 1 relative to the reaction chamber base 5.

The product holder 6 is a chamber surrounding the reaction chamber. The holder is defined by holder walls 7 but could simply be defined by the reaction chamber wall 2 and insulation 8. The product holder is dimensioned to hold a vertical stack of beer cans extending around the perimeter of the reaction chamber (although is could also be adapted to hold beverage per se as in the first embodiment).

In use, beverage or beverage containers 12 are provided in the product holder 6 and solid reactant (ammonium nitrate prills) is provided in the reaction chamber 1 suspended from the reaction chamber base 5 by the perforated support plate 4. Initially, when no liquid reactant has been introduced into the reaction chamber, the float 11 rests on the reaction chamber base 5. When cooling of the beverage is desired, a liquid reactant (water) is added to the reaction chamber through the inlet 3. As water is added, the float will rise within the reaction chamber as it will be buoyed up by the water. The buoyancy of the float is selected such that the water/air interface lies within the bulk of the solid reactant supported on the perforated support. In the area of overlap between the solid reactant 9 and the water, dissolution of the solid reactant occurs to form a cold/saturated and therefore dense cooling liquid. The cooling liquid sinks to the reaction chamber base 5 and this sets up a free convention flow in the space between the perforated support and the reaction chamber base. The free convention flow aids efficient mixing of the reactants and thus results in rapid dissolution of the solid reactant.

In both embodiments described above, the cooling liquid is cooler than the beverage (assuming the beverage to be at an ambient temperature). This temperature differential causes heat to be transferred from the beverage in the product holder to the cooling liquid thus resulting in cooling of the beverage.

The embodiments have been described by way of example only and various modifications will be readily apparent to those skilled in the art.