GB2329392A

GB2329392A - Self-cooling containers of beverage and foodstuffs

Info

Publication number: GB2329392A
Application number: GB9720009A
Authority: GB
Inventors: William Dando; Lisa Jane Paine; Jonathan Russell Tippetts
Original assignee: Bass PLC
Current assignee: Bass PLC
Priority date: 1997-09-20
Filing date: 1997-09-20
Publication date: 1999-03-24
Anticipated expiration: 2017-09-20
Also published as: GB9720009D0; GB2329392A8; GB2329392B

Abstract

A self-cooling beverage (or foodstuff) container comprising: a beverage (or foodstuff) chamber having beverage (or foodstuff) retained in it; a solvent chamber having pressurised solvent retained in it; a pressurised gas dissolved in the pressurised solvent; pressurisation means adapted to hold the pressurised solvent with its dissolved gas at a pressure above atmospheric pressure; de-pressurisation means adapted to release the pressure in the solvent chamber; the arrangement being such that, in use, when the pressurised solvent chamber is de-pressurised the dissolved gas comes out of solution and expands, extracting heat from the solvent/beverage system, there being heat transfer means adapted to transfer heat from the beverage to the solvent and/or to the gas released from the solvent, the overall result being a cooling of the beverage (or foodstuff).

Description

IMPROVEMENTS IN AND RELATING TO SELF-COOLING CONTAINERS OF BEVERAGE AND FOODSTUFFS This invention relates to self-cooling containers of beverages, such as cans of beverage (soft drinks or alcoholic drinks such as beer), and to self-cooling containers of foodstuffs.

It is been desired for many years to produce a self-cooling can for beverages (and foodstuffs). The following will discuss beverages, but the invention is also applicable to cooling food. There have been many proposals, but none have been successful commercially.

Three main techniques have previously been proposed: using an endothermic reaction to cool a liquid that is in thermal contact with the beverage (e.g. dissolving a powder in water); using the latent heat of transformation to cool the beverage as a liquid boils to a gas (or in the case of solid CO2 sublimes to a gas) to cool the beverage; and using the rapid expansion of a pressurised (possibly liquefied) gas to cool a beverage in thermal contact with the liquefied gas/highly pressurised gas.

Recently, there has been a proposal by The Joseph Company to cool a beverage by allowing a pressurised liquid hydrofluorocarbon to be de-pressurised and undergo boiling and rapid expansion, taking advantage of the thermal energy required to undergo the phase change and that required to expand the gas produced. The Joseph Company say that this will be put into production in 1997.

We aim to provide an alternative way of providing self-cooling beverage (or food produce) containers.

According to a first aspect of the invention we provide a selfcooling beverage or foodstuff container comprising: a beverage (or foodstuff) chamber having beverage (or foodstuff) retained in it; a solvent chamber having pressurised solvent retained in it; a pressurised gas dissolved in the pressurised solvent; pressurisation means adapted to hold the pressurised solvent with its dissolved gas at a pressure above atmospheric pressure; de-pressurisation means adapted to release the pressure in the solvent chamber; the arrangement being such that, in use, when the pressurised solvent chamber is de-pressurised the dissolved gas comes out of solution and expands, extracting heat from the solvent/beverage system, there being heat transfer means adapted to transfer heat from the beverage to the solvent and/or to the gas released from the solvent, the overall result being a cooling of the beverage (or foodstuff).

Thus, we use the release of a gas from a solvent to cool, rather than the boiling of the solvent or a liquid-to-gas phase change of the solvent. This is different from the prior art discussed above. It allows us to use different solvents than have previously been used, and in some embodiments to retain a substantial part of the solvent in the container after the cooling operation has been performed. This can reduce atmospheric pollution.

The fact that we do not need a liquid that will boil at room temperature means that we are not forced to use HFC's, which are increasingly being found to be bad for the environment.

Of course, we prefer to choose the solvent-dissolved gas system to be such that the gas that is released to atmosphere is environmentally acceptable. At present, we prefer to use carbon dioxide (CO2) as the gas, or perhaps nitrous oxide (N2O). Ideally, we would like to use nitrogen as the gas (or a noble gas), but as brewers we are not fully familiar with all known solvents. A man skilled in the art of solvent does, of course, know all known solvents and may well be able to identify one which dissolves nitrogen well, and which will give a satisfactory result. We do seek protection for that combination.

We prefer the solvent to have a relatively low boiling point. This can help since it can contribute evaporative cooling effects.

Of course, if the man skilled in the art of solvents knows of the existence of an acceptable solvent that dissolves a lot of an acceptable gas, and that is liquid when pressurised but gaseous at room temperature and pressure, we would envisage using that solvent-gas combination, and seek protection for that. We would then get phase-change heat extraction, as well as dissolved gas to non-dissolved gas heat of solution cooling, and gas expansion cooling.

We prefer the solvent to have a boiling point of 60"C or less, or 50"C or less, or 45"C or less, or 30"C or less, or 20"C or less, or 10 C or less, or 0 C or less, or -20 C or less, or to have the boiling point in the ranges defined at or between the above value.

By "acceptable solvent" and "acceptable gas" we mean ones that are not going to hurt a user (e.g. non-toxic) and than are reasonably acceptable to the environment. We prefer that they not be HFC's and not be other substances which are known to damage the Ozone layer substantially.

We have identified one solvent that is acceptable, and that is methylal (dimethoxymethane: CH3-0-CH2-0-CH3) This has a boiling point at normal atmospheric pressure of 42.3 C.

It is non-toxic. It is not a HFC. It is especially useful because it is in commercial production. It has the very useful property of being able to dissolve enormous amounts of CO2 (and nitrous oxide). We can, at about 7 bar, get about 20% by mass CO2 dissolved in methylal.

By getting so much gas dissolved we can get substantial cooling as the gas comes out of solution and expands to atmospheric pressure.

We prefer to keep the expanded (cold) gas in contact with the beverage container for some time as it escapes to atmosphere, so as to allow time for heat transfer. This can be achieved by using narrow escape channels, and increasing the path length for escape (non-direct, winding, escape route).

We prefer to pressurise the solvent/dissolved gas to at least 2 or 3 bar, and preferably to 4, 5 or 6 bar or above. We have found that with methylal and CO2 about 7 or 8 bar may be the optimum, with about 20% by weight CO2 dissolved in the methylal. We may go to 9, 10, 11, 12 bar or above, possibly up to 15 bar or above, but at present a container with its solvent pressurised to 7 or 8 bar is seen as desirable. This is not so high a pressure as to require massive containers, but enough to get a lot of CO2 dissolved.

We prefer to arrange a container/beverage (or foodstuff)/solvent/gas so as to achieve in use a temperature drop of the beverage (or foodstuff) of 50C or more, or 10 C or more, or 15"C or more, or 200C or more, 25"C or more, 30"C or more, or even 35"C or 40"C or more.

The amount of gas dissolved in the solvent is preferably at least 3%, or at least 5%, or at least 10%, or at least 15%, or at least 20%, or 25% or more (mass of gas to mass of solvent). Alternatively the amount of dissolved gas could be in the range 5-10%, 10-15%, 15-20%, 20-25%, or more.

The ratio of mass of beverage to (or foodstuff) solvent (+ gas) is such as to achieve a desired cooling.

We may not vent the evolved gas directly to atmosphere. It may never reach atmosphere (or a substantial fraction of the evolved gas may never reach atmosphere).

We may arrange for the gas evolved from the solvent to be released into the beverage (or foodstuff). If the gas is passed directly through the beverage there is direct thermal contact between the cold gas and the beverage, which may be a desirable way of cooling the beverage.

Preferably the gas is CO2, or N2, or a CO2/N2 mixture.

In the case of beer, ale, lager, stout, and the like, releasing or venting the gas through the beverage may help in head formation when the beverage is dispensed. Many so-called "widget devices" have a stream of bubbles passing through the beer to form nucleation sites for a good head.

Our device may perform the dual function of achieving significant cooling and head generation/enhancing. When the gas is CO2/N2/COz + N2 mixture we may be able to use the evolved gas from the solvent to assist in providing the desired dissolved gas content of the beer. For example we may dissolve less (or significantly less) CO2/N2 in the beer during the filling process of the container than we desire to be present in the beverage during dispensing of the beverage and/or in the beverage in the glass immediately post-dispense.

We may allow a significant period of time between beginning to evolve gas from the solvent and opening the beverage container (long enough to cool, and also possibly long enough for evolved gas to be dissolved in the beverage).

We may vent all of the evolved gas through the beverage or foodstuff or only a portion of it. The act of de-pressurising the beverage (or foodstuff) chamber may trigger venting of evolved gas through the beverage/foodstuff, preferably via a mechanism that is dependent upon the change from pressurised beverage to unpressurised beverage.

Instead of, or in addition to, passing the evolved gas through the beverage or foodstuff we may provide trap means adapted to prevent the gas, or at least some components of the gas, from reaching atmosphere.

The trap means may comprise an expansion chamber, which may initially be provided at a low pressure (possibly below atmospheric pressure), and possibly an evacuated chamber. We may provide a flexible, stretchable, vent chamber, possibly at least partially outside of rigid walls of the container, the vent chamber swelling as gas is evolved.

We may provide adsorption, or pressure-reducing, means adapted to hold evolved gas. The adsorption means may both prevent the evolved gas from reaching atmosphere and reduce the pressure of gas above the body of solvent, thereby facilitating more evaporation of solvent/evolving of gas out of the solvent.

The adsorption means may comprise activated charcoal, or a zeolite, or a dessicant, or some other thing that captures at least a component of gas. We may prefer to capture harmful substances and allow to pass less harmful substances (e.g. water).

Venting none or little gas to atmosphere reduces pollution and the environmental impact of the containers.

We may provide thermal insulation around the adsorption means.

Absorbing a gas can be an exothermic process, and since we wish to cool the beverage (or foodstuff) we may thermally insulate the absorbent material.

The adsorbent material may be provided in a vent chamber, and many occupy substantially less than the whole volume of the vent chamber.

We may throttle the gas outlet from the container (which may be a metal can, or a plastics can, or a metal or plastics can or bottle), or a composite structure with different materials for different structures which, in use, experience different forces.

The beverage may have a dissolved gas (e.g. CO2 and/or N2) and may be pressurised. Typical pressures for the beverage may be about 1 bar. The beverage is preferably beer, ale, lager, porter, cider, stout, or the like, but it could be a soft drink.

When a gas comes out of solution there may be a heat of solution involved. This can be an endothermic effect, which can help cool the solvent.

When gas comes out of solution, it is initially very, very, tiny bubbles. These expand rapidly. The gas that is evolved from the surface of the solvent may also continue to expand (depending what is the top gas pressure at that instant). This will cause expansion cooling.

As bubbles rise to the surface of the solvent small droplets of solvent will be carried into the top gas above the body of the solvent, and this will promote faster evaporation /semi-forced boiling of the solvent, which will also cool the gas above the body of the solvent. A low boiling point solvent will have a greater degree of evaporation/spray cooling in this way.

We prefer to have at least 1% to 5% of the mass of the solvent evolved during the gas venting operation, and possibly 5% to 10%, 10%-15% or even 20% (or more) of the solvent mass evolved.

Alternatively, we may wish to minimise or restrict solvent loss, and the figures given above may be upper limits to acceptable loss of solvent.

In addition to believing methylal to be a good solvent for our invention, we want to protect methylal-like solvents: those with a similar chemical structure and/or which have similar physical properties so far as the cooling process is concerned. It may be possible to modify the methylal molecule to enable it to dissolve CO2 (or another gas) better.

We may use a mixture of substances as the solvent (e.g. methylal plus other substances, such as ethanol, or dimethyl ether). The solvent preferably contains at least some methylal, and preferably at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%, or about 100% methylal (% by mass, or by mole-per-cent), or any range defined between the figures listed.

We may dissolve more than one sort of gas in the solvent. It may be possible to get more total gas moles dissolved into a solvent by dissolving more than one gas. Similarly, it may be possible to get more of a gas (e.g. CO2) (or a mixture of gases) into a given volume of solvent if the solvent is a mixture of compounds.

We may prefer to have a methylal/water mixture as the solvent.

Methylal is miscible in water at practically all concentrations, which enables us to have a mixture that has a significant water content.

Releasing a methylal/water mixture into the environment has less of an environmental impact than releasing pure methylal - water is seldom seen as being environmentally harmful. We may prefer to have a relatively large volume of solvent because it may be easier to control/release gas over a long extended time than to do so with a smaller volume of solvent with the same amount of gas dissolved in it. Mixing a desired amount of methylal (or the like gas-holding liquid or material) with a volume of water may enable us to reduce the environmental impact and slow down the gas release (and extend the cooling effect over a longer time), in comparison with an equivalent mass of pure methylal.

Altering the relative amounts of different components of the solvent may enable us to alter the solubility of selected gases in the solvent mixture.

Preferably the solvent is saturated with gas (e.g. substantially pure methylal saturated with CO2, or a methylal mixture saturated with CO2, or a CO2/N2 mixture). The gas may be a mixture of CO2/N2, typically at a suitable ratio found in an alcoholic beverage. The ratio of CO2/N2 in the gas evolved from the solvent may be above, at, or below, the ratio of CO2/N2 present in the beverage.

The solvent may be super-saturated with gas. We may dissolve gas in the solvent at a dissolving pressure (e.g. 15 bar) which is higher than the storage pressure in the solvent chamber once the container has been manufactured (e.g. 7 bar). This may enable us to get even more gas into a given volume of solvent. The ratio of dissolving pressure to storage pressure may be at any point at or between the following figures: 4:3, 3:2, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 20:1, 30:1, 40+:1.

The temperature of the solvent at a super-saturisation operation may be different from room temperature. If the gas dissolves better when the solvent is cold, it may be well below room temperature. The temperature for dissolving the gas in the solvent may be a little above its freezing point, or at least generally near its freezing point. The dissolving temperature may be 30"C, 20"C, 10 C, 0 C, -10 C, -20 C, -30 C, -40 C, -50 C, -600C, -70 C, -80 C or below, or in any range defined between those points/values.

According to a second aspect of the invention we provide a method of providing a self-cooling beverage (or foodstuff) container comprising dissolving gas in a solvent liquid, retaining the solvent liquid in the container at a pressure that is significantly above atmospheric pressure, de-pressurising the solvent so as to cause gas to come out of the solution, and using the expansion of the freed gas to cool the beverage (or foodstuff) .

Preferably the gas also has an exothermic heat of solution so that when it comes out of solution there is an endothermic effect. The method preferably also comprises using that endothermic effect to cool the beverage (or foodstuff). Preferably at least some of the solvent is evaporated/vaporised during the release of its dissolved gas, requiring heat of vaporisation to be provided, and the method may use this as a further cooling effect to cool the beverage (or foodstuff).

Preferably the method comprises providing the solvent and beverage (or foodstuff) in thermal communication in the container. It may be possible to arrange for substantially all of the heat transfer to occur between cold gas and the beverage (or foodstuff), but we much prefer to have heat transfer between the cooled solvent and the beverage or foodstuff (as well, or predominantly).

The method preferably comprises selecting methylal as the solvent, or a solvent that has high levels of methylal.

We may add to the solvent a substance that renders the solvent and/or it vapour non-inflammable, or which reduces the flammability of the solvent and/or its vapour.

The container may be a single use disposable container, or we may provide the container in a form adapted to be re-used or recycled. A customer may be encouraged to return a used container to us for re-cycling. We may be able to re-use the container or re-use the cooling mechanism. The container may comprise a beverage (or foodstuff) chamber adapted to be coupled to a cooling cartridge. The cooling cartridge may comprise the solvent chamber and may be releasable from the container, possibly only after discharge of the beverage and/or gas from the cooling cartridge. We may be able to re-charge the cooling cartridge with gas, or with solvent, or with gas dissolved in solvent.

We may simply receive used containers and separate out the container bodies and cooling cartridges for independent re-cycling/waste disposal. This gives us control over how the spent cartridges are re-cycled or disposed of.

The beverage (or foodstuff) container may be re-fillable with beverage (or foodstuff) and may be re-usable.

There now follows some examples of the present invention which are intended as examples, and are not limiting. Some of the examples will refer to the accompanying drawings of which: Figure 1A shows an unopened can; Figure 1B shows a can that has been opened; Figure 1C shows a can that has been opened and allowed to stand for a while; Figure 2 shows schematically another can; Figure 3 shows a shell of a can receiving a cooling insert; Figure 4 shows a container where evolved gas is released into the beverage or foodstuff; Figure 5 shows a container where evolved gas is released into absorbent material; Figure 6 shows a container where evolved gas is trapped in an expansion chamber; and Figure 7A and & B shows a further cooling insert.

Example 1 In a volume of methylal is pressurised to 7 bar and has 80% by mass methylal and 20% by mass CO2 dissolved in it we expect, upon rapid de-pressurisation to atmospheric pressure, a temperature fall of the methylal of about 27"C.

Examples 2 to 6 These are given in the table below:

Example Starting Pressure Mass (%) Mass (%) Temperature (bar a) Methylal CO2 Drop C No. 2 10 80 20 30 No. 3 5 80 20 23 No. 4 7 80 20 26 No. 5 10 75 25 31* No. 6 10 95 5 14 * Accuracy Warning In all cases the temperature fall that we expect to see is with the final pressure being 1 bar (atmosphere). The starting temperature of the (substantially pure) methylal is about 30 C - a hot day's temperature.

As will be seen above, Examples 1 and 4 (with pressures of about 7 or 8 bar) give us results where we expect to see around 80 to 90% of the temperature drop that using 50% more pressure does (see Examples 2 and 5).

Having a lot more COz dissolved does not seem to give a linear effect, but it is true that the more CO2 dissolved the higher the temperature drop.

In Example 1, about 27% of the methylal solvent vents as vapour, leaving about 73% of its mass as a cold liquid.

The above shows that dissolving CO2 in methylal under pressure and then de-pressurising the methylal produces significant cooling. The methylal and CO2 is vented to atmosphere, but CO2 is a natural gas and the amounts involved will not damage the environment, and methylal too is non-toxic. The fact that perhaps a quarter of the volume of methylal escapes is possibly not a major effect in cooling: the methylal acts as a container or reservoir for CO2 ( or nitrous oxide).

The specific heat of methylal is about half that of water, which means that for a given heat of solution/heat of expansion exchange the temperature of the methylal changes twice as much as would water, resulting in a greater beverage-methylal temperature difference and therefore a more efficient heat exchange between the methylal-beverage.

If we consider Figure 1, this shows a can 1 having a beverage chamber 2 surrounding a solvent chamber 3, beverage 4 in the beverage chamber, and solvent 5 (methylal) in the solvent chamber. It is at room temperature T1.

The inner solvent chamber initially is at, say, 6 bar and is depressurised in a controlled way to atmospheric pressure. Dissolved CO2 gas and some solvent escapes, absorbing energy from the remaining solvent, thereby cooling down the solvent 5 to a temperature T2, and cooling the solvent chamber 3. This is shown in Figure 2.

Heat then flows from the beverage 4 to the solvent 5, via the walls of the solvent chamber 3 (which may well be made of metal - good thermal conductivity, and good strength) until the temperatures reach (or roughly approach) equilibrium at a temperature of T3. It may be necessary to allow the can to stand for half-a-minute, one minute, oneand-a-half minutes, two minutes, or even more than two minutes. We prefer to have approximate equilibrium achieved in under five minutes, and preferably under four minutes, and most preferably under three minutes. The evolving of gas from the beverage may take place in a matter of seconds, but we prefer to control it to take tens of seconds, or even a minute or two.

If we have a can with 330g of beverage and about 450g of an 80/20 (by weight) solution of methylal and CO2 at a pressure of 7 bar gauge (about 100 psig) in the inner solvent chamber we aim to achieve an initial temperature drop of about 27"C for the methylal (or rather for the 73% by weight of the methylal that is left behind, the remainder venting).

This will produce a temperature drop of the beverage of about 10 C.

We envisage using CO2 (or N2O) dissolved in methylal as a replacement for more damaging greenhouse gasses. For example, as an alternative to the HFC's used in the Michel-Joseph (Joseph Company) can. We refer the reader to any published patent applications, or articles, on the Michel-Joseph can (e.g. those in the name of The Joseph Corporation or The Joseph Company) and incorporate by reference their disclosure. We would envisage replacing the liquid that is boiled in that technology with CO2 dissolved in methylal. HFA 134a is the solvent preferred by Joseph, but they simply boil it and expand it, without dissolving lots of "benign" gas in it.

Methylal has been commercially available for twenty years or more. The desire to produce self-cooling cans/containers has been around for much the same time. We are the first to realise that the two things can be brought together in a way that works acceptably.

Turning now to Figure 2, this shows a cylindrical can 20 having an outer metal shell 21, a can end 22 attached to the top of the shell, a tab opening device 23 to enable a user to open the can to drink from it, and a central cylindrical can insert 24. The insert 24 has a central solvent chamber 25 and a plurality of axially extending peripheral capillary channels 26 around its circumferential periphery. The channels 26 extend to the bottom of the can and are ventable to atmosphere. An aperture 27 communicates the solvent chamber 25 with the channels 26. The solvent chamber 25 contains substantially pure methylal 27 which is supersaturated with CO2. The solvent chamber 25 is pressurised to 8 bar.

A de-pressurisation device 29 is provided to de-pressurise the solvent chamber, gas (and entrained/vaporised solvent) escaping along channels 26.

The can shell 21 in combination with the outer walls of the channels 26 defines a beverage chamber 30 which contains a beverage 31 (which may be beer, lager, ale, cider, stout or some other alcoholic beverage), or it may be cola, lemonade, orange juice, water, or some other soft drink (carbonated or still).

As the cold CO2 gas passes along channels 26 it is slowed down to increase the heat exchange time. Valve means may be provided to assist in this. The surface area for heat exchange is high - adjacent channels 26 may define grooves between their channel-defining walls, or fins may be provided.

After activating the de-pressurisation device 29, the user allows the can to stand for about one minute. He then may or may not give it a small shake/activates agitation means to release even more CO2 from the methylal. The user then (possibly after waiting a little longer) opens the tab 23 and can drink the beverage.

An insulation layer or coating may be provided associated with the shell 21. Instead of having an insert 24 in contact with the beverage, the shell may have an internal cylindrical wall 35 defining an internal annular space 36, opening to the base of the can, and the insert may co-operate with that. This is illustrated in Figure 3. The channels 26 could then be defined between the outer surface of the insert 24 and the wall 35.

Figure 4 shows a cooling insert 24 which has means 38 for releasing evolved gas into the body of a beverage 31. The means 38 comprise, in this example, gas outlets 39 provided near the base of the can, the gas (e.g. CO2) travelling down channels in thermal contact with the beverage 31 before it reaches the outlets 39. This ensures that the gas cools the beverage as it progresses towards the outlets 39. When the gas is bubbled into the beverage it also continues to cool the beverage. Some of the gas may be dissolved in the beverage after it leaves the outlets 39.

The gas that dissolves in the beverage may augment any gas dissolved in the beverage upon filling of the beverage chamber (and the gas content of the beverage may be depressed to allow for boosting by evolved gas).

Alternatively the gas content of the beverage may be as normal, with little or no effect on gas content due to evolved gas from the solvent being additionally dissolved.

Figure 4 also shows, at 39, an alternative where the outlets are spaced away from the bottom of the container/beverage chamber. This leaves a body of beverage which does not have gas passed through it which may be helpful if passing gas through the whole of the height of the beverage produces too large a head. The outlet 39' may be at or near the top of the can. There may be outlets at two or more heights of the can, and they may have different sizes/cross sections, or be throttled differently in some other way. This may enable us to control how much gas evolved from the solvent is passed into different regions of the beverage.

There may be filter means in the flow path for evolved gas, from the solvent to the beverage. The filter means may filter out solvent and allow only gas to pass. The filter means may filter out some or all of a component of the evolved gases, and/or some or a component of solvent that is evolved/contacted with the gases. It would almost certainly be undesirable to allow methylal to enter the beverage.

Figure 5 shows a metal can 20 having a cooling insert 24 comprising a removable cartridge 40 provided with actuation means 41.

The cartridge 40 has a methylal/water solvent 42 (e.g. 80% methylal/20% water, by weight) with a CO2/N2 gas mixture dissolved in it.

A trap 42 of activated charcoal is provided associated with the cartridge. When the pressure in the solvent chamber is released by the user pressing/manipulating the actuation means 41 CO2/N2 is evolved and leaves the body of solvent and enters peripheral passageways 43, and then progresses on to downwardly extending passageways 44. The gas then passes back up upw below atmospheric pressure, thereby assisting in the evaporation of the solvent itself (to be adsorbed) and/or further de-gassing of the solvent.

The can of Figure 5 is adapted to be returned to us for recycling.

We remove the cartridge 40 and replace the adsorbent material 42 (which may be provided in its own cartridge form). We also re-charge the solvent chamber of the cartridge with methylal/water (or some other solvent) with dissolved gas and pressurise it, and seal the cartridge, providing new actuation means if necessary, or re-setting the old actuating means.

The solvent cartridge may be replaced/recycled whilst leaving the adsorbent material unchanged (which may be good/for a plurality of re-uses).

The beverage chamber may be re-fillable and re-sealable.

We may extract spent solvent from the solvent chamber prior to re-filling. We may re-use the shell of the can, or it may be scrapped/sent for scrap re-cycling. If we have the used cans returned to us we can control their disposal/recycling. As an incentive to return the cans/containers we may have a refund of part of the purchase price, or discount off the next full container. The containers may include competition/prize-winning means indicative of winning a possible prize, such means preferably only being evaluatable at a recycling station to see if the possible prize has actually been won.

The high pressure solvent chamber is likely to be most usefully re-used since it may be relatively expensive to make something capable of holding the pressures we envisage using.

Figure 6 shows a container, e.g. can, where evolved gas passes down channels 50, back up channels 51, and to vent chamber 52. The evolved gas is not released to atmosphere. Chamber 52, with its evolved cold gas, assists in cooling the beverage.

In the embodiment shown the cans may have a central blind bore at their base into which the cooling cartridge is inserted. The cartridge and bore are typically cylindrical.

Figure 7A and 7B show a plan view of a cooling insert 70 which is flatter than those shown previously and which has the evolved gas move in a circular or spiral path at an upper surface (possibly ribbed for heat transfer). The gas is evolved tangentially. The diameter of the insert of Figure 7 is about 1H2 to 3 that of the can/container in which it is placed.

The insert 70 is a combined cooling device and head-generating widget.

Separate actuation means may be provided for the cooling devices shown, or they may be self-actuated when the beverage chamber of a can is opened (e.g. actuated by the pressure drop in the beverage chamber).

To put the present invention into context, we would need about 33g of liquid nitrogen to cool 330ml of beverage by 10 C (most beverages are basically water, and have similar heat capacities). We would need about 900g of compressed nitrogen at room temperature, compressed to 200 bar.

We would need about 225g of compressed CO2 at room temperature, compressed to 60 bar.

Pressures of 60 bar and above are likely to be impractical.

Once we thought to look for cooling effects associated with depressurising a liquid so that gas comes out of solution we looked at standard soft drinks (e.g. plastics PET bottles of sparkling water and cola available in supermarkets) and noted that when they are opened there is a temperature drop of the order of 1"C or 2"C - not large, but a drop is present. The amount of CO2 dissolved in a typical soft drink is about 3 vols/vol, or about 6g/litre. Since water is 1000g/litre, this is about 0.6% by mass - much, much, less than the 10% or 20% by mass CO2 in methylal that we aim for.

For the avoidance of doubt, we also seek protection for a can or other container part-way through production that has no beverage in it, but does have an insert adapted to receive the solvent. We also seek protection for an insert which contains solvent and gas (e.g. methylal and CO2) pressurised and adapted to be incorporated in a beverage container.

Our foodstuffs beyond beverages to which the present invention is applicable include yoghurts and ice cream.

Although the cooling mechanism described has been provided as an insert, it could be integrally provided with the can or other container, or provided in some other non-insert way. We also seek protection for such non-insert containers (filled with beverage or food, or unfilled, and loaded with solvent and dissolved gas or unloaded).

Claims

CLAIMS 1. A self-cooling beverage (or foodstuff) container comprising: a beverage (or foodstuff) chamber having beverage (or foodstuff) retained in it; a solvent chamber having pressurised solvent retained in it; a pressurised gas dissolved in the pressurised solvent; pressurisation means adapted to hold the pressurised solvent with its dissolved gas at a pressure above atmospheric pressure; de-pressurisation means adapted to release the pressure in the solvent chamber; the arrangement being such that, in use, when the pressurised solvent chamber is de-pressurised the dissolved gas comes out of solution and expands, extracting heat from the solvent/beverage system, there being heat transfer means adapted to transfer heat from the beverage to the solvent and/or to the gas released from the solvent, the overall result being a cooling of the beverage (or foodstuff).
2. A container according to Claim 1 in which the solvent is not a hydrofluorocarbon.
3. A container according to Claim 1 or Claim 2 in which the gas that is released to atmosphere is environmentally acceptable.
4. A container according to Claim 3 in which the gas comprises carbon dioxide.
5. A container according to Claim 3 or Claim 4 in which the gas comprises nitrous oxide.
6. A container according to any preceding claim in which the gas comprises nitrogen.
7. A container according to any preceding claim in which the gas has a boiling point of 60"C or less, or 50"C or less, or 45"C or less, or 30"C or less, or 20"C or less, or 10 C or less, or 0 C or less, or -20 C or less.
8. A container according to any preceding claim in which the solvent comprises methylal.
9. A container according to Claim 8 in which the solvent is entirely, or substantially, methylal.
10. A container according to any preceding claim in which the pressurised solvent and its dissolved gas is pressurised to at least 2 or 3 bar.
11. A container according to Claim 10 in which the pressurised solvent and its dissolved gas is pressurised to 4, 5 or 6 bar or above.
12. A container according to any preceding claim in which the pressurised solvent and its dissolved gas is pressured to about 7 or 8 bar.
13. A container according to any preceding claim in which the pressurised solvent and its dissolved gas is pressured to 15 bar or above.
14. A container according to any preceding claim which is arranged to achieve a temperature drop of the beverage of 5"C or more.
15. A container according to any preceding claim which is arranged to achieve a temperature drop of the beverage of 10 C or more.
16. A container according to any preceding claim which is arranged to achieve a temperature drop of the beverage of 15"C or more.
17. A container according to any preceding claim which is arranged to achieve a temperature drop of the beverage of 20"C or more.
18. A container according to any preceding claim in which the amount of gas dissolved in the solvent is at least 3% by mass (mass of gas compared to mass of solvent).
19. A container according to any preceding claim in which the amount of gas dissolved in the solvent is at least 5% by mass.
20. A container according to any preceding claim in which the amount of gas dissolved in the solvent is at least 10% by mass.
21. A container according to any preceding claim in which the amount of gas dissolved in the solvent is at least 15% by mass.
22. A container according to any preceding claim in which the amount of gas dissolved in the solvent is at least 20% by mass.
23. A container according to any preceding claim in which the beverage has a dissolved gas (e.g. CO2 and/or N2) and is pressurised.
24. A container according to Claim 23 in which the beverage is pressurised to about 1 bar above atmospheric pressure.
25. A container according to any preceding claim in which when the gas comes out of solution there is an endothermic effect, which in use helps to cool the solvent.
26. A container according to any preceding claim in which when the gas comes out of solution it expands and causes expansion cooling.
27. A container according to any preceding claim in which when the gas comes out of solution bubbles rise to the surface of the solvent and small droplets of solvent are carried into the top gas above the body of the solvent, promoting faster evaporation of the solvent.
28. A container according to any preceding claim in which, in use at least 1% /3to to 5% of the mass of the solvent is lost (leaves the body of solvent) as the dissolved gas comes out of solution from the solvent.
29. A container according to any preceding claim in which more than one sort of gas is dissolved in the solvent.
30. A container according to any preceding claim in which the solvent is saturated with gas.
31. A container according to Claim 30 in which the solvent is substantially pure methylal substantially saturated with CO2.
32. A container according to any preceding claim in which the solvent may be super-saturated with gas.
33. A container according to any preceding claim which comprises a can having a methylal, or methylal-based solvent which contains about 20% dissolved CO2 (20% weight of CO2, 80% weight of solvent) and which has the methylal/dissolved CO2 pressurised to about 7 or 8 bar.
34. A container according to any preceding claim having vent means adapted to vent the dissolved gas such that it does not vent directly to atmosphere.
35. A container according to any preceding claim which has gas retention means such that the evolved gas does not reach atmosphere (or a substantial fraction of the evolved gas does not reach atmosphere).
36. A container according to Claim 34 or Claim 35 in which the gas evolved from the solvent is released into the beverage (or foodstuff).
37. A container according to Claim 36 in which the vent means or gas retention means releases gas into the beverage so as to generate a head on the beverage when the beverage is dispensed, or so as to generate a better (e.g. bigger or more stable) head upon beverage dispense.
38. A container according to any one of Claims 35 to 37 in which all of the evolved gas is vented through the beverage.
39. A container according to any one of Claims 35 to 38 in which is arranged such that the act of de-pressurising the beverage (or foodstuff) chamber triggers the passage of evolved gas through the beverage/foodstuff via a mechanism that is dependent upon the change from pressurised beverage to unpressurised beverage.
40. A container according to any one of Claims 34 to 39 which comprises trap means adapted to prevent the gas, or at least some components of the gas, from reaching atmosphere.
41. A container according to Claim 40 in which the trap means comprises an expansion chamber adapted to receive evolved gas from the solvent.
42. A container according to Claim 41 in which the trap means is initially provided at a low pressure (possibly an evacuated chamber).
43. A container according to any preceding claim comprises adsorption, or pressure-reducing, means adapted to hold evolved gas.
44. A container according to Claim 43 in which the adsorption means both prevents the evolved gas from reaching atmosphere and reduces the pressure of gas above the body of solvent, thereby facilitating more evaporation of solvent/evolving of gas out of the solvent.
45. A container according to Claim 43 or Claim 44 in which the adsorption means comprises activated charcoal, or a zeolite, or a dessicant, or some other things that captures at least a component of gas.
46. A container according to any one of Claim 43 to 45 which has thermal insulation between the adsorption means and the beverage and/or exterior wall of the container.
47. According to any one of Claims 43 to 47 in which the adsorbent material is provided in a vent chamber.
48. A container according to any preceding claim in which the solvent comprises a methylal/water mixture.
49. A container according to Claim 48 adapted in use to release the dissolved gas from the solvent over a longer time than an equivalent container would release the same volume of gas dissolved in the same volume of pure methylal as is present in the methylal/water mixture.
50. A container according to any previous claim which is a single use dispensable container.
51. A container according to any one of Claims 1 to 49 which is adapted to be re-used or recycled.
52. A container according to Claim 51 which comprises a beverage (or foodstuff) chamber adapted to be coupled to a removable/separable cooling cartridge.
53. A container according to Claim 52 in which the cooling cartridge comprises the solvent chamber.
54. A container according to Claim 51 or Claim 52 which has a cooling cartridge that is adapted to be recharged with gas, or with solvent, or with gas dissolved in solvent.
55. A container according to any preceding claim which is re-fillable with beverage (or foodstuff) and which is re-usable.
56. A container according to Claim 55 which has the beverage or food chamber re-pressurisable during re-filling.
57. A container substantially as described herein with reference to the accompanying drawings.
58. A method of providing a self-cooling beverage container comprising dissolving gas in a solvent liquid, retaining the solvent liquid in the container at a pressure that is significantly above atmospheric pressure, de-pressurising the solvent so as to cause gas to come out of the solution, and using the expansion of the freed gas to cool the beverage.
59. A method according to Claim 58 in which the gas has an exothermic heat of solution so that when it comes out of solution there is an endothermic effect which cools the beverage.
60. A method according to Claims 58 or 59 in which the gas which comes out of solution expands and cools the solvent or beverage by virtue of its emission.
61. A method according to Claims 58 to 60 in which at least some of the solvent is evaporated/vaporised during the release of its dissolved gas, requiring heat of vaporisation to be provided, and thereby cooling the beverage.
62. A method according to any one of Claims 58 to 61 comprising providing the solvent and beverage in thermal communication in the container.
63. A method according to any one of Claims 58 to 62 in which the solvent is methylal, or contains high levels of methylal, and in which the gas is CO2 or N2O.
64. A method according to any one of Claims 58 to 63 which comprises passing evolved gas through the beverage or solvent.
65. A method according to any one of Claims 58 to 64 which comprises preventing the release to atmosphere of substantially all, or substantially part of, evolved gas.
66. A method according to Claim 65 comprising holding the evolved gas with adsorption means.
67. A method according to Claim 65 comprising retaining evolved gas in a vent chamber.
68. A method of cooling a beverage substantially as described with reference to the accompanying drawings.
69. A method of providing a beverage or foodstuff container according to any one of Claims 1 to 56, the method comprising dissolving the gas in the solvent at one pressure and/or temperature, introducing the solvent and its dissolved gas to the solvent chamber, closing the solvent chamber and/or container, and allowing the pressure in the solvent chamber and/or temperature there to be different during the storage and use of the filled container from the temperature and/or pressure experienced by the solvent during the gas-dissolving operation, thereby super-saturating the solvent with gas.
70. A method according to Claim 69 in which the pressure at which the gas is dissolved in the solvent is significantly higher than that at which the solvent is held in the solvent chamber during storage and use of the container.
71. A method according to Claim 69 or 70 in which the temperature at which the gas is dissolved in the solvent is significantly lower than the storage and use temperature of the container.
72. A solvent chamber adapted for use in a container according to any one of Claims 1 to 56, the solvent chamber containing a solvent having a gas dissolved in it and being adapted to be de-pressurised so as to allow the gas to come out of solution and cool the solvent.
73. An insert adapted to be coupled with a container body to form a container having an insert, the insert having: a solvent chamber provided with pressurised solvent retained in it, and having a pressurised gas dissolved in the pressurised solvent; pressurisation means adapted to retain the pressurised solvent with its dissolved gas at a pressure above atmospheric pressure; and de-pressurisation means adapted to relieve the pressure in the solvent chamber do as to enable, in use, dissolved gas to come out of solution and expand, extracting heat from the solvent.
74. An insert according to Claim 73 having heat transfer means adapted to transfer heat, in use, from the contents of the container to the solvent.
75. An insert substantially as described herein.
76. A container shell adapted to be filled with beverage or food and containing an insert, the insert being in accordance with any one of Claims 73 to 75 but not yet containing solvent and associated dissolved gas (but being adapted to be so filled).
77. A container shell substantially as described herein.