TECHNICAL FIELD

The present invention relates to the cooling of fluids through a wall, in particular but not exclusively beverages contained in a package.

BACKGROUND

Cooling packaged fluids presents a challenge. To maximise heat exchange in other applications, fluids that need to be cooled are flowed in high surface area heat exchangers, with conductive fins and plates for thermal contact and a method of pumping the fluid is used to minimise boundary layers and ensure even temperatures are achieved. However packaged fluids are much more difficult to cool quickly, they do not have fins or plates, packages are often cost optimised by minimising wall material and therefore minimising surface area, at least to a degree. Wall materials aren't selected for thermal conductivity, and there is no way to pump or duct the beverage to flow over the cooled surface. If cooling is applied to a package wall, the layer of fluid at the wall cools, but the lack of flow or mixing and relatively low thermal conductivity of the fluid means the bulk of the fluid that is further from the wall is left uncooled, and the rate of cooling of the packaged fluid as a whole is very slow after the layer close to the wall is cold. The prior art available to overcome this best utilise spinning of the package, either horizontal spinning such that the air bubble in the package stirs the cooled fluid away from the surface (as used in the Cooper Cooler US7703301), or forcing and collapsing a vortex in the fluid by spinning and stopping to create mixing (as provided in the Envirocool V-Tex

EP2459840).

Cooling times provided are still slower than many applications require. In order to maximise cooling rate a large temperature difference is used to drive cooling.

In the pursuit of faster cooling, however, there is a problem; particularly in cooling packaged beverages, but also in other applications, there is often a need to rapidly cool fluids at temperatures close to the freezepoint of the fluid, such that the cooling medium driving the cooling needs to be at a temperature below the freeze point in order to provide a high enough temperature difference to drive high heat flux in order to achieve a satisfactory cooling rate.

While increasing heat flux improves the cooling rate to a point, if the cooling heat flux is too high, the fluid local to the wall can freeze, preventing it from being stirred away. A frozen layer can form on the cooled wall which creates an effective insulating barrier significantly slowing cooling. If the fluid is a carbonated beverage the frozen layer traps C02 in a foamy layer further worsening this effect. While the mixing achieved by the spinning approaches mentioned above helps refresh the wall with warmer fluid, frozen layer formation limits the achievable cooling rates near the freeze point of the fluid.

Furthermore it is sometimes advantageous to cool a fluid comprising a slurry of frozen and unfrozen fluid or even freeze a portion of an unfrozen fluid in order to make a part frozen slurry, for example a slush beverage. In these circumstances, frozen layer formation will occur, and without a method of managing the frozen formation it will affect both frozen slurry consistency and cooling rates.

DISCLOSURE OF INVENTION

According to a first aspect of the present invention, there is provided apparatus to cool a fluid through a wall, where the apparatus provides a cooling medium to accept heat from a first side of the wall such that the wall is cooled causing heat from the fluid to flow into a second side of the wall, wherein the temperature of the cooling medium is below a freezing point or glass transition temperature of at least a constituent of the fluid, and the apparatus applies a series of shock accelerations for at least a period of time within the time spent cooling the fluid through the wall.

The apparatus may be adapted to accept at least one insert comprising a fluid and a wall.

Also provided is the method of cooling a fluid through a wall, by providing a cooling medium to accept heat from a first side of the wall such that the wall is cooled causing heat from the fluid to flow into a second side of the wall, wherein the temperature of the cooling medium is below a freezing point or glass transition temperature of at least a constituent of the fluid, and applying a series of shock accelerations for at least a period of time within the time between starting cooling and finishing cooling the fluid through the wall.

The method is preferably applied to at least one insert comprising a fluid and a wall.

The insert may further comprise a feature to enable the insert to be opened by hand such as a screw cap or a ring-pull or frangible feature such as a scored feature or a membrane. The insert may be a packaged fluid where the package comprises the wall. The package may be one of a bottle, can, tin, sachet, bag or pouch. Preferably the package is one of a bottle, can or tin. The wall may be a flexible, semi-rigid or rigid membrane or other substantially impermeable barrier. The wall may be substantially made of one of aluminium, steel, stainless steel, glass, polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE) or another polymer, or a laminate or other combination of materials comprising at least one of aluminium, steel, stainless steel, glass, PET, PP, PE, or another polymer.

The fluid may be a liquid or a part frozen slurry of frozen and unfrozen liquid. The fluid may be a beverage. The fluid may be carbonated. The way by which the cooling medium accepts heat may be by at least one of convection, conduction, radiation, most preferably substantially conducting to a medium physically contacting the first side of the wall, the cooling medium may or may not be a fluid that then convects the heat away.

The cooling medium may be a fluid, and may be a liquid. The cooling medium may be a solid arranged to substantially contact the wall.

The shock accelerations at the wall may be applied by applying acceleration motions to the insert.

The apparatus may be configured to hold the wall or insert such that it can apply acceleration motions to the insert or to strike the wall or insert to create the acceleration motions.

The apparatus may comprise a feature to hold the insert such that acceleration motions can be imparted to the insert. Holding may be achieved by one or more of clamping, clipping, sliding into a taper fit or friction fit, an elastic grip where the insert at least partially compresses the grip, or applying at least one of suction, air pressure or a magnetic field.

The acceleration motions may be applied to the insert in any linear direction or be applied as angular acceleration around any axis, or be applied as a combination of the two. Preferably the acceleration motions are applied such that the shock acceleration direction is substantially in a tangential plane locally at the wall. Most preferably the acceleration motions are applied to the insert as angular accelerations about a central axis of the insert, especially for substantially rotationally symmetric or axisymmetric inserts.

The shock acceleration may comprise a peak acceleration of at least 100 m/s ² at the wall, preferably a peak acceleration of at least 250 m/s ² at the wall, and most preferably a peak acceleration of at least 1000 m/s ² .

The peak acceleration may occur over an angular travel of 5°, for example up to 5°. Preferably the peak acceleration may occur over an angular travel of less than 1 °.

The peak acceleration may occur within a maximum duration of 0.2 seconds.

The peak acceleration may be defined as the full width at half maximum (FVVHM) for any waveform representing the series of shock accelerations.

The shock accelerations may be applied at least once every 5 seconds. Preferably the shock accelerations may be applied at least once every second. Most preferably the shock accelerations may be applied at least 3 times per second.

The shock accelerations may be in any direction relative to the instantaneous motion of the wall including in a retrograde direction (deceleration). Preferably the acceleration motion is applied such that it moves the package while leaving the fluid weakly accelerated substantially only by shear from the wall by substantially avoiding applying acceleration to the fluid out of plain of the package wall.

Most preferably the apparatus is adapted to receive an insert of substantially axisymmetric form, and apply angular acceleration motions about the axis of the form of the insert.

The apparatus may use an impact to produce the shock acceleration. The impact may be between two or more features or components in the drive mechanism of the apparatus or the impact may comprise striking the insert

Also provided is a system comprising the apparatus described and at least one insert comprising a fluid and a wall.

According to a second aspect of the present invention, there is provided apparatus to cool a fluid through a wall, where the apparatus provides a cooling medium to accept heat from a first side of the wall such that heat from the fluid flows into a second side of the wall, wherein the cooling medium is at least one solid body adapted to close to a substantially intimate thermal contact with an insert, the insert comprising the fluid and the wall. The apparatus applies a series of shock accelerations for at least a period of time within the time spent cooling the fluid through the wall.

The cooling medium may provide a compressive load to the insert. The cooling medium may comprise a flexible element that can be wrapped or tightened around the insert. The cooling medium may deform to substantially intimately contact at least a region of the first surface of the wall. The cooling medium may deform at least a region of the first surface of the wall. The cooling medium may comprise two or more bodies that together clamp the insert. Preferably the closing of the cooling medium around the insert causes a deformation of the wall of the insert such that the first surface of the wall substantially intimately contacts a region of the surface of the cooling medium. The contacting region of the cooling medium may be shaped substantially as a negative of a region of the wall it contacts. The contacting region of the cooling medium may be shaped approximately as a negative of a region of the wall it contacts with variation from the exact negative such that the variation in compressive force over the surface of the wall is lower. The deformation imparted as a result of compressive force may be mostly elastic or preferably substantially entirely elastic.

The cooling medium may comprise a feature to hold the insert such that it can apply acceleration motions to the insert as provided in the first aspect of the invention.

The cooling medium may be moveable to an open position where the insert is substantially not clamped and can be inserted or removed with relative ease. According to another aspect of the present invention, there is provided apparatus for cooling a fluid, comprising: a cooling medium arranged to accept, in use, an insert comprising a fluid contained by a wall such that the cooling medium is in thermal contact with a first side of the wall and causes heat from the fluid in contact with a second side of the wall to flow through the wall to the first side to cool the fluid; and a drive mechanism arranged to apply a series of shock accelerations to the wall of the insert for a period of time during cooling of the fluid.

It will be appreciated that the drive mechanism of such apparatus imparts shock acceleration motions to an insert, in use, in a way that is different to any known previously. What is meant by a series of shock accelerations is a series of short (in duration) and intense (in magnitude) accelerations. When such accelerations are applied to the wall of the insert, the wall tends to move rapidly relative to the body of fluid contained by the wall, due to inertia effects, resulting in local forces at the wall but little or no bulk movement of the contained body of fluid. As the fluid is being cooled as the same time, this has the effect of releasing any ice crystals tending to form at the wall so that an ice layer cannot build up on the second side of the wall and interfere with heat transfer through the wall.

As described above, the cooling medium may be at a temperature that is below a freezing point or glass transition temperature of at least a constituent of the fluid. This ensures that the cooling medium has a freezing effect on a given fluid, for example the fluid or types of fluid expected to be contained in the insert. For example, the cooling medium may be at temperature of 0° or less, preferably 5° or less, further preferably 10° or less, and further preferably 15° or less.

The shock accelerations may be applied to the wall of the insert as linear accelerations, angular accelerations, or any combination of the two. However the Applicant has found it is preferable that the shock accelerations are applied, in use, as primarily angular accelerations. This means that the wall of the insert moves angularly while leaving the fluid in contact with the second side of the wall only weakly accelerated by shear forces at the wall. It is advantageous to avoid apply accelerations to the fluid in a direction perpendicular to the plane of the wall. In various embodiments the shock accelerations are applied, in use, in a direction that is locally substantially tangential to the wall.

The nature of the shock accelerations is that they are small-range but high-magnitude movements. In one or more embodiments, the shock accelerations are applied, in use, over an angular range of movement of up to 5°. In one or more embodiments, the shock accelerations are applied, in use, over an angular range of movement of less than 1 °.

The intense shock accelerations are much larger in magnitude than any acceleration or deceleration that might be experienced by a package when it starts or stops rotation, e.g. in a pulsed rotation regime. In one or more embodiments, the shock accelerations comprise a peak acceleration of at least 10g, 25g, 50g or 100g.

The intense shock accelerations are much shorter in duration than any stop-start cycles that might be experienced by a package in a pulsed rotation regime. In one or more embodiments, the shock accelerations comprise a peak acceleration occurring within a maximum duration of 0.2 seconds, preferably a maximum duration of 0.02 seconds and further preferably a maximum duration of 0.002 seconds.

The peak acceleration may be defined as the full width at half maximum (FWHM) for any waveform representing the series of shock accelerations.

The shock accelerations are applied much more frequently than any cycles of pulsed rotation used to create a collapsing vortex. In one or more embodiments, the shock accelerations are applied, in use, at least once every 5 seconds. In one or more embodiments, the shock accelerations are applied, in use, at least once every second. In one or more embodiments, the shock accelerations are applied, in use, at least 3 times per second.

There will now be described various preferred features of this aspect of the invention, some of which overlap with features already disclosed above.

In a set of embodiments, the apparatus may further comprise means to support the insert such that the insert is moveable relative to the cooling medium by the drive mechanism. In such embodiments, the drive mechanism applies the series of shock accelerations directly to the insert, causing it to move relative to the cooling medium. In such embodiments, the drive mechanism may comprise the means to support the insert. For example, the drive mechanism grips the insert by one or more of clamping, clipping, sliding into a taper fit or friction fit, an elastic grip where the insert at least partially compresses the grip, or applying at least one of suction, air pressure, or a magnetic field.

In one or more of these embodiments, the insert is supported, in use, in a cavity in the cooling medium. Preferably the drive mechanism is arranged to apply the series of shock accelerations by imparting angular accelerations to the insert within the cavity.

In one or more of these embodiments, the cavity comprises a wall to separate the cooling medium from the insert.

In one or more of these embodiments, the cavity is sized to provide a close fit with the insert in use. For example, the close fit may allow for linear and/or rotational sliding movement of the insert in the cavity.

In one or more of these embodiments, the cavity is substantially axisymmetric about a central axis. In one or more of these embodiments, the cavity is substantially cylindrical about a central axis. In one or more of these embodiments, the drive mechanism is arranged to apply the series of shock accelerations as angular accelerations about the central axis of the cavity. In one or more of these embodiments, the cavity comprises a low friction surface.

In addition to any of these embodiments, or alternatively, the apparatus may further comprise a means for conveying the insert within the cavity. The conveying means may act to draw in or control movement of the insert into the cavity. The conveying means may act to eject, or control ejection of, the insert. The conveying means may use physical contact, such as a moving piston or suction cup. The conveying means may operate by moving air to create a pressure difference on the insert. Preferably the means for conveying the insert within the cavity comprises a means of actively moving air in and out of the cavity. In one or more of these embodiments, the means for conveying is arranged, in use, to pump air out of the cavity such that the insert is pressed against the insert holder by the partial vacuum that is created. In one or more of these embodiments, in addition or alternatively, the means for conveying is arranged, in use, to pump air into the cavity such that pneumatic pressure below the insert raises the insert at least partially out of the cavity.

The means of actively moving air may act to perform both tasks of applying shock accelerations and conveying the insert within the cavity. For example, the drive mechanism may also comprise a or the means of actively moving air in and out of the cavity. For example, the drive mechanism may be arranged to apply the series of shock accelerations to the wall of the insert by pumping air into and/or out of the cavity in short bursts. In addition to any of these embodiments, or alternatively, the cavity comprises an insert holder having a high friction e.g. rubberised surface to support the insert.

In another set of embodiments, the cooling medium may comprise at least one solid body defining a cavity arranged to grip the insert, in use, and wherein the drive mechanism is arranged to apply the series of shock accelerations to both the cooling medium and the insert. In one or more of these embodiments, the solid body may provide a compressive load to the insert in use. In one or more of these embodiments, the solid body may deform to be in intimate physical contact with at least a region of the first side of the wall in use. In one or more of these embodiments, the solid body may comprise at least a flexible portion that can be tightened around the insert in use. In one or more of these embodiments, the cooling medium may comprise two or more solid bodies that clamp together to form the cavity arranged to grip the insert.

In one or more of these embodiments, the cavity is substantially axisymmetric about a central axis. In one or more of these embodiments, the cavity is substantially cylindrical about a central axis. In one or more of these embodiments, the drive mechanism is arranged to apply the series of shock accelerations as angular accelerations about the central axis of the cavity.

Further to any of the embodiments and aspects of the invention disclosed hereinabove, or alternatively, the apparatus may further comprise means to rotate the insert, in use, at a substantially constant rate. The Applicant has found that spinning the insert, in particular at relatively high speeds, can provide centrifugal ice separation in addition to the effects of the shock accelerations. Preferably constant rate is between 300 rpm and 600 rpm, and more preferably between 450 rpm and 600 rpm.

In one or more of these embodiments, the means to rotate the insert applies a rotation about a substantially vertical axis. The insert may be tilted by up to 10-15 degrees relative to the axis of rotation, as any air bubble in the insert (e.g. a beverage package) remains as a headspace above the fluid and does not substantially interfere with the effects at the wall. Such angled rotation works even for carbonated fluids. If the fluid is not carbonated then, in other embodiments, the means to rotate the insert may apply a rotation about a substantially horizontal axis. This may result in chaotic stirring with air bubbles but may not change the effect of the shock accelerations.

In one or more of these embodiments, the means to rotate the insert applies a substantially constant rotation about the same axis as the shock accelerations are applied as primarily angular accelerations. In one or more of these embodiments, the insert is rotated, in use, while in a or the cavity in the cooling medium. The cavity may be substantially

axisymmetric about a central axis. The cavity may be substantially cylindrical about a central axis. The means to rotate the insert may be arranged to rotate the insert about the central axis.

In one or more of these embodiments, the means to rotate the insert is part of the drive mechanism.

In one or more of these embodiments, the inserted is rotated, in use, at the same time as the series of shock accelerations is applied such that the resulting motion of the insert is a superposition of the rotation at a substantially constant rate and the series of shock

accelerations. For example, the apparatus may comprise means to apply the series of shock accelerations for at least a period of time within the time spent cooling the fluid through the wall, and means to spin an insert about a substantially vertical axis, such that any ice crystals that form are pulled away from the wall by action of centrifugal separation. The resulting motion of the insert may be the superposition of a substantially constant rotation and occasional shock angular accelerations around an axis. The superposition may result in instantaneous slowing, stopping, reversal or increase in rotational velocity, depending on the relative magnitude and direction of the constant rotation and the shock accelerations.

According to another aspect of the present invention, there is provided apparatus for cooling a fluid, comprising: a cooling medium arranged to accept, in use, an insert comprising a fluid contained by a wall such that the cooling medium is in thermal contact with a first side of the wall and causes heat from the fluid in contact with a second side of the wall to flow through the wall to the first side to cool the fluid; and a drive mechanism arranged to apply a series of shock accelerations to the wall of the insert, and arranged to rotate the insert at a substantially constant rate, in use, for a period of time during cooling of the fluid.

Various embodiments of this aspect of the invention may have any of the features disclosed hereinabove.

In addition to any of these embodiments, or alternatively, the cooling medium is a fluid. The cooling medium may be air. The cooling medium may be a chilled aqueous solution of propylene glycol.

In addition to any of these embodiments, or alternatively, the cooling medium is below a freezing point or glass transition temperature of at least a constituent of the fluid, e.g. below 0 degrees. . For example, the cooling medium may be at temperature of 0° or less, preferably 5° or less, further preferably 10° or less, and further preferably 15° or less.

In addition to any of these embodiments, or alternatively, the cooling medium comprises at least one solid body comprising channels through which a cooling fluid is circulated in use. The cooling medium may comprise one or more solid bodies defining a cavity to accept the insert in use. In one or more of these embodiments, the cavity is substantially axisymmetric. In one or more of these embodiments, the cavity is substantially cylindrical.

There is further provided a system comprising the apparatus according to any of the embodiments and aspects of the invention disclosed hereinabove, and further comprising an insert accepted in the cooling medium, the insert comprising a fluid contained by a wall such that the cooling medium is in thermal contact with a first side of the wall and causes heat from the fluid in contact with a second side of the wall to flow through the wall to the first side to cool the fluid.

In one or more of these embodiments, the wall of the insert is a substantially impermeable barrier for the fluid contained by the wall.

In one or more of these embodiments, the fluid is a liquid or a part-frozen slurry of ice and liquid.

In one or more of these embodiments, the insert is a drinks package, such as a can, bottle or tin.

In one or more of these embodiments, the insert has a substantially axisymmetric form and the series of shock accelerations is applied as angular accelerations about the central axis of the insert.

According to another aspect of the present invention, there is provided a method of cooling a fluid, comprising: providing an insert comprising a fluid contained by a wall and placing a cooling medium in thermal contact with a first side of the wall so as to cause heat from the fluid in contact with a second side of the wall to flow through the wall to the first side to cool the fluid; and using a drive mechanism to apply a series of shock accelerations to the wall of the insert for a period of time during cooling of the fluid.

Various embodiments of this aspect of the invention may have any of the features disclosed hereinabove.

BRIEF DESCRIPTION OF DRAWINGS

Some embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic cross-section of a first embodiment;

Figure 2 is a view of a beverage can that has been cooled without shock acceleration, and then cut open after pouring out all flowable contents to show an ice layer adhered to the wall;

Figure 3 is a graph showing a comparison of the cooling rate provided by an embodiment of this invention in comparison to the prior art approach of intermittent spinning at different starting temperatures, showing the gain in performance achieved when cooling near the fluid freeze-point;

Figure 4 is a diagram to show the effect of different acceleration motions on an insert;

Figure 5 is a diagrammatic cross-section of the insert when cooled in an apparatus according to an embodiment of the invention;

Figure 6 is a diagrammatic side projection of another embodiment (in open and closed positions;

Figure 7 is a diagrammatic cross-section of the embodiment of Figure 6;

Figure 8 is a diagrammatic cross-section of another version of the embodiment of Figure 6; Figure 9 is a diagrammatic top projection of another embodiment;

Figure 10 is a diagrammatic cross-section of the embodiment of Figure 9; and

Figure 11 is a schematic graph showing a series of shock accelerations to be applied by a drive mechanism in use.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to the figures, and particularly referring to Fig. 1 , a first embodiment of apparatus (1) to cool a fluid (2) through a wall (3), where the apparatus provides air as a cooling medium (4) to accept heat from a first side (21) of the wall such that heat from the fluid flows into a second side (20) of the wall, wherein the temperature of the cooling medium (4) is below a freezing point or glass transition temperature of at least a constituent of the fluid (2), and the apparatus applies a series of shock accelerations for at least a period of time within the time spent cooling the fluid (2) through the wall (3).

In this embodiment the apparatus (1) is adapted to accept a canned beverage as an insert (5) comprising a beverage fluid (2) enclosed in an aluminium or steel wall (3) with a ring-pull opening. The beverage (2) enclosed in the can (5) starts as a liquid, and during cooling ice is generated such that the can contains a part frozen slurry of frozen and unfrozen liquid at the end of the cooling. To avoid a build-up of an ice layer (13) adhered to the walls, such as is shown in Fig. 2, which would both be difficult to pour from the can and would prevent efficient cooling of the bulk of the liquid due to the insulating properties of the layer, a drive mechanism (6) is provided. To be simple to replicate, this embodiment utilises an impact driver (7) acting on a drive clip (8) that is firmly clipped to the can (5). A brake (9) is applied to the drive clip (8) in order to engage the impact action from the impact driver (7). The braking torque may be adjusted between high torque, which gives a predominantly stationary can with angular accelerating-decelerating shocks applied approximately 5 times a second, to a lower torque where the can rotates as well as receiving the shock accelerations. The rotating mode allows the additional advantage of stirring the fluid using the bubble (10) trapped in the can (5), but is not necessary to remove the ice layer.

The cooling medium (4) in this embodiment is highly turbulent air being flowed through a close fitting gap according to WO 201 1042698, using a fan (1 1 ) to recirculate it over cooling coils (12), to cool down to -40°C, and then over the first side (21 ) of the wall (3) to accept heat from the wall.

While we have shown this embodiment with a can as the insert (5), it is clear that this embodiment, with simple modification to the ducting diameter and drive clip to accept a bottle, would prevent ice layer formation with a bottle equally well. Glass or plastic bottles may significantly slow the cooling rate but aluminium bottles such as Alumni-Tek® (a trademarked name by the manufacturer Ball) bottles should achieve comparable cooling rates.

A second embodiment is provided that uses the impact driver-brake drive mechanism from the first embodiment but the can is directly submerged in a tank of chilled aqueous solution of propylene glycol at -15°C to closely replicate the cooling method used in the patent EP2459840 that describes the intermittent spinning approach, allowing a direct performance comparison. Using the brake at high torque such that rotation is prevented, shock accelerations are imparted that are able to remove ice crystals forming on the inside of the can wall but little stirring of the bulk occurs. With reference to Fig. 3, it was shown in our tests that at higher temperatures (e.g. starting cooling from 24°C), where ice formation is less likely, the intermittent spinning (white bar, left) approach achieved a faster cooling rate than the unspun + shock accelerations approach of this invention (black bar, left), as expected. However, when cooling from a lower starting point, ice formation begins to dominate; starting at 3°C the cooling rate achieved by the unspun + shock accelerations of this invention (black bar, right) is higher than the rate achieved by intermittent spinning (white bar, right). This demonstrates the efficacy of shock accelerations at removing the frozen layer of fluid at the wall independently of any spinning or other mixing that may be used in combination. Using shock accelerations in combination with other methods of inducing mixing from the prior art, such as the intermittent spinning or horizontal spinning will give further improvements.

With reference to figures 4 and 5, the advantage of shock angular accelerations (19) about the axis of a substantially axisymmetric insert (d, e) is it allows the acceleration to be in the tangential plane of the package wall in all locations on the wall, meaning the wall is not accelerated into (15) or away from (14) the fluid. This has three significant advantages:

1. All the acceleration acts to create shear force (18) between the wall and the fluid, promoting slip of the wall (17 to 17') past the fluid, including any frozen parts of the fluid (16), along the wall, the easiest direction to release ice adhered to wall (16'). Acceleration of the wall into the fluid will press the frozen layer into the wall, not acting to remove the ice layer, and acceleration of the wall away from the fluid needs to overcome the vacuum generated separating the frozen layer away from the wall.

2. If a wall accelerates in towards the fluid (15), the inertia of the fluid acts to slow the acceleration for a given applied force, or conversely increases the force requirement for a given acceleration

3. If sufficient acceleration away from the fluid to overcome the vacuum generated is applied cavitation will occur which is detrimental because it will dissipate significant amounts of energy as heat, may risk leaking by causing damage to the wall, and, if the fluid is carbonated, is likely to cause carbonation to come out of solution, making the insert likely to spill over if subsequently opened.

Referring to Fig. 4, any linear acceleration motions (a, b) will have an entire side (a, b: 15) where the wall is accelerating into the fluid and an entire side (a, b: 14) where the wall accelerates away from the fluid. Rotary acceleration motions that do not act around the axis of the package also have regions (c: 15) where the wall is accelerating into the fluid and regions (c: 14) where the wall accelerates away from the fluid.

With reference to Fig. 5, shock acceleration (19) of the wall (3) tangential to the wall that causes it to move to position (17') where it would have been in position (17") without such an acceleration, creates a shear (18) acting to accelerate the body of fluid (2), but due to the high acceleration the fluid (2) will not accelerate immediately, creating a relative slip (22) at the wall (3). A particle of frozen fluid (16) initially on the second surface (20) of the wall (3) will be encouraged to slip both due to its own inertia and also due to the drag it would receive if it were to move through the fluid (2) to follow the wall (3). As it slips to its new position (16') a thin layer of fluid that is wetted onto the region of wall (3) that moves to directly under the particle can get between the wall and the frozen particle, releasing it from the wall. With reference to figures 6 and 7, another embodiment is provided using a solid cooling medium. This embodiment comprises a cooling medium comprising three rigid solid cooling bodies (4a, 4b, 4c) that move together between an open position (a), where clearance (24) allows insertion and removal of a semi rigid insert (25) (e.g. a beverage can), and a closed position (b), where there is intimate thermal contact between the cooling bodies (4a, 4b, 4c) and the first or outer wall (21 ) of the insert (25). The cooling bodies (4a, 4b, 4c) form a solid body adapted to close to intimate thermal contact with the insert (25). In order to achieve good thermal contact, over-centre toggle clamp linkages (23) apply high force to close the cooling bodies (4a, 4b, 4c) together in order to apply compression to the insert (25). Any mismatch between the internal form of the cooling bodies (4a, 4b, 4c) and the shape of the wall of the insert (25) is taken up as small elastic deformations of the insert wall. The toggle clamp linkages (23) are driven by a collar (28) to make the drive tolerant to angular misalignment from the angular acceleration motion freedom. In this drive mechanism the cooling medium, i.e. the cooling bodies (4a, 4b, 4c), is clamped onto the insert 25 and they are moved together to impart a series of shock accelerations. In order to accept heat from the wall of the insert (25) each of the cooling bodies (4a, 4b, 4c) is provided with internal flow paths (29) connected by flexible hoses (30) to a coolant circulation loop where coolant such as an aqueous solution of propylene glycol can be circulated at low temperature to cool the cooling bodies. Alternatively braided flexible hoses could be used to connect the flow paths as the evaporator in a vapour compression refrigeration circuit, for example using R404A refrigerant adding challenges to sealing due to a higher operating pressure, but increasing the cooling capacity available.

Use of three bodies (4a, 4b, 4c) enables compression to be applied across the surface without need to deviate from the shape of the insert. Fig. 8 shows that for a two body version of this embodiment, the edges (26) don't achieve compression without extra interference (27, exaggerated) that may scratch the insert.

An alternative embodiment for cooling fully rigid inserts could use a flexible cooling medium body such as a wrap that is tightened around the insert like a wide hose clip with a means of cooling on the outer surface, such as fins in a cold air flow. A drive mechanism similar to the internal workings of an impact driver, where two sprung pairs of inclined planes meet in impact every half revolution and then spring away, acting against an elastic static mount is stiffly coupled to drive shaft (31) in order to apply angular acceleration motion to both the insert and the cooling medium and therefore to give shock acceleration to the cooled wall of the insert.

In another embodiment the insert is fitted slidably within the cooling medium sleeve, such that at least a region of the first surface of the wall of the insert is in close proximity for heat transfer, while the slidable fit enables the insert to rotate with shock accelerations separate from the cooling medium such that the cooling medium sleeve does not move with the shock accelerations. The total accelerated moment of inertia (rotational inertia) to which accelerations are applied is thereby greatly reduced, minimising harm from vibrational damage and maximising amplitude of ice removal acceleration achieved. The benefit of the higher amplitude of shock accelerations more than outweighs the reduced heat conduction due to less intimate contact at the heat transfer surface for most applications as there is a reduction in power (both consumed power and heating caused), noise and the potential for vibration related damaging for a given performance of ice removal. Flexible fluidic coolant links are also not required, improving reliability, and reducing cost and complexity of manufacture.

With reference to Figures 9 and 10, a detailed embodiment of apparatus using a solid cooling medium (32) in sliding contact with an insert (36), is provided. In this embodiment a beverage can may be used as the insert (36), although other packages with cylindrical walls may also be used. In the illustrations and description an aluminium beverage can is used.

This embodiment provides a cylindrical cavity (35) through the cooling medium (32) to accept an insert (36) with a matching cylindrical external first side of a wall, such that the cavity (35) and the first side of the wall are close for substantially intimate thermal contact while the relative sizing leaves sufficient but minimal clearance (34) for sliding with little friction. The clearance (34) is a very small air gap between the surfaces. If too much friction is present, heat build-up may occur, preventing cooling of the insert (36). Ideally the insert (36) is free to slide in any direction relative to the cavity (35) in the cooling medium (32). The insert (36) is supported in the cavity (35) by an insert holder (39).

The apparatus in this embodiment comprises means of supplying chilled coolant to the cooling medium (32). For example, this provides chilled coolant in cooling channels (33) within the cooling medium (32) thereby cooling the cooling medium (32) such that it accepts heat from a first side of the wall, leading to heat from the fluid in the insert (36) flowing into a second side of the wall. The cooling medium (32) extends approximately as high as the insert's cooled wall, and is surrounded by a thermally insulating casing (42), through which the cavity (35) also passes. The cavity (35) is sized for a close sliding fit with the insert (36) such that the insert (36) may be slid axially, and in rotation, relative to the cooling medium (32) with little friction, but is constrained to be coaxial with the cavity (35) and cannot rattle.

The cooling medium (32) may be a solid block of a material having high thermal conductivity, such as aluminium. The cooling channels (33) may be formed directly in the cooling medium (32) or embedded, for example in the form of copper coils to carry the coolant fluid.

As seen in Fig. 10, a means of moving air is provided to move air in and out of an air space (43) below the insert (36). By pumping air out of a channel (40), a partial vacuum is created in the air space (43) below the insert (36) such that the insert (36) is pressed against the insert holder (39) by the differential pressure of atmospheric air over the partial vacuum created below the insert (36). The insert holder (39) may be a suction cup with the air channel (40) passed through a rotary seal directly to the suction cup, such that the partial vacuum is applied locally, or, as illustrated, the entire cavity below the insert (36) may be pumped to a partial vacuum where a passage (41) is included for air to escape from directly beneath the insert (36) past the insert holder (39) to maximise the area over which the pressure differential acts. While this means the vacuum needs more air to be pumped, due to leakage through the sliding clearance (34), it can simplify the drive train to move the insert holder (39).

Using a high friction, compliant surface such as a soft silicone rubber where the insert (36) contacts the insert holder (39) maximises traction to apply shock accelerations, although it should be noted this layer should be thin to minimise damping of accelerations, which both reduces applied accelerations and generates heat. We found a 1 mm layer of 60 Shore A silicone rubber bonded to a nylon base worked well.

Due to the minimal clearance (34), unassisted removal of inserts (36) when required can be challenging, especially with inserts (36) without any neck or other features to grab easily such as beverage cans. Allowing air to move in through the air channel (40) prevents the user pulling against a vacuum but, in this embodiment, means for actively moving air into the cavity (43) below the insert (36) is used, such that the pneumatic pressure below the insert (36) raises the insert (36) to present the easy to grab exterior to the user for easier removal. Careful monitoring and control of pressure and flow can prevent potential safety concerns by avoiding unintentional firing of the insert (36) out of the cavity (35).

To aid sliding, and, if required, minimise leakage air, the internal wall is machined smooth and then polished. A smooth low friction and/or hard coating may improve performance and/or life but has not been found to be essential.

The embodiment comprises means to apply a series of shock rotary accelerations for at least a period of time within the time spent cooling the fluid through the wall. The means to apply shock accelerations comprises a shock accelerations generator (37) that generates angular shock accelerations, and a transmission means (38) to transmit shock accelerations to the insert holder (39). A rotary seal is provided around the transmission means (38) to facilitate pneumatic functionality described above. The shock accelerations generator (37) can be one of a number of options. If rotational separation of ice is not required, a motorised eccentric bearing acting on a lever (such as an oscillating multi-tool head) works very well, as does the impact driver and brake combination previously described. Using the apparatus described with the motorised eccentric bearing lever to generate 1.6° shock accelerations at 10,000 RPM (giving a peak acceleration at the surface of a 53mm OD can of approximately 400m/s ² ) to cool a 250ml can of carbonated beverage with approximately 27g sugar content and no fat, starting at 0°C and with the aluminium cooling medium cooled to -38°C, we found it took 90 seconds to create an acceptable, pourable slush beverage without need for a constant rotational motion to be superimposed with the series of shock accelerations.

Figure 1 1 is a schematic graph showing a series of shock accelerations to be applied by a drive mechanism. The shock accelerations are for a 10.000RPM drive of a +/- 1.6 degree oscillator acting at 26mm radius. Acceleration is shown on the Y axis (44) in m/s ² and time is shown on the X axis(45) in ms. The peak acceleration, referred to elsewhere in the application, is given by the full width half maximum (FWHM (46)), which in this case occurs over a period of 2ms, as shown in Figure 11.

In addition to any of the drive mechanisms described above, we have found that by constantly spinning the insert (36) vertically, we can centrifugally separate and constrain the ice portion generated to the centre of the insert (36), which lowers the ice fraction at the wall, helping to achieve higher ice fractions. While this complexity is not always required, we have found it can help, especially where beverage recipes are challenging (such as lower sugar or higher fat content). We have found that best separation occurs at a constant rotational speed of over 300 RPM, and little additional gain occurs above 600 RPM for a 53mm OD insert. However, to gain the benefit of the fourth aspect of this invention, the shock accelerations generator (37) must generate angular shocks on a spinning insert (36). This can be achieved by using the same broadly stationary shock accelerations in combination with a means of adding the shocks to a rotary motion, such as applying the shocks to the carrier of an epicyclic gear set and applying the rotary motion to ring gear such that the sun gear is the superposition of both motions. Alternatively, the shock accelerations generator (37) may create the accelerations using a variable drive ratio system such as a gearbox with non-circular gears, which may reduce noise. The resulting motion of the insert (36) is a superposition of a substantially constant rotation and occasional shock angular accelerations around an axis. The superposition may result in instantaneous slowing, stopping, reversal or increase in rotational velocity, depending on the relative magnitude and direction of the constant rotation and the shock accelerations.

Other ways of applying shock accelerations to the insert are available. These include but are not limited to reciprocating rotary mechanisms (such as oscillating multi-tool type), variable ratio drive mechanisms, impact mechanisms (such as impact driver type), hydraulic actuators and impulse generators (such as used in the Rigid Stealth Force product), pneumatic actuators, oscillators and vibrators, vibrations applied by solenoids or high torque motors such as stepper motors, eccentric mass vibrators, and induction motors applying pulses of force electromagnetically.