WO2021156350A1

WO2021156350A1 - Fluid containment vessels and accessories therefor

Info

Publication number: WO2021156350A1
Application number: PCT/EP2021/052636
Authority: WO
Inventors: Declan FEARON; Marek REBOW; Richard Woods
Original assignee: Freezadome Limited
Priority date: 2020-02-08
Filing date: 2021-02-04
Publication date: 2021-08-12

Abstract

A fluid containment vessel such as a glass (10) has a base and an interior volume for containing a fluid above the base. A sealed internal void (20) is provided in the base, which is separated from the interior volume (16) of the vessel (10) by an upper wall (14). A temperature control structure (22) is situated within the internal void (20), and comprises a thermal energy absorbing material and a compressible member. The thermal energy absorbing material comprises water and a thickening agent such as sodium polyacrylate or a natural gum, and may optionally include a freezing point depressant and/or an open cell foam such as a copper foam to promote thermal conductivity within the thermal energy absorbing material. The temperature control structure (22) substantially fills the internal void (20), and the compressible material is sufficiently large in volume and sufficiently compressible to absorb the thermal expansion arising when said thermal energy absorbing material is cooled to below 0°C. There is also provided an accessory having a thermal energy absorbing material in a void of a body structure. The body structure is adapted to be inserted in a drinking vessel and has means for securing in place within the vessel. Embodiments of the invention include improved beer and wine glasses, and plastic domes which are inserted into the base of drinking vessels.

Description

Fluid containment vessels and accessories therefor

Field of the Invention

The present invention relates to fluid containment vessels and in particular to drinking vessels that are adapted to be chilled below ambient temperature so as to lower the temperature of the contents of the vessel. The invention also relates to accessories for such vessels to lower the temperature of the contents of the vessel.

Background of the Invention

Normally it is desirable when consuming beverages to maintain the beverage at a suitable temperature (a serving temperature), which may be above or below ambient temperature.

Conventional rates of consumption of beverages such as beer are usually at a relatively slow rate such that the beverages remain exposed to normal ambient temperatures for sustained periods of time. Consequently, the temperature of the beverage steadily rises towards ambient temperature as it is being consumed with a corresponding loss of desirability for the beverage. For example, all beers should be served between 3.5 and 13°C, but lagers may be served colder than ales, and certain ales may be served colder than stouts. Beers served at near-frozen temperatures retain more CO2 gas (resulting in a more filling experience for the consumer). Carbonated cider can be served from anywhere between 4°C and 6°C. However, it is difficult to provide a way of ensuring the optimum serving temperature for a range of different beers from a bar, let alone to give the consumer any choice in the serving temperature.

The optimum serving temperature for enjoyment of full-bodied white wines and fruity reds involves refrigerating or chilling the wine bottle to say 10 -15°C, while light and dry white, dessert and anything sparkling are at their best from 4°C to 10°C. Red wines are normally served and enjoyed at close to normal room temperature at say 12-18 °C . This is problematic on an airplane, where due to space limitations for refrigeration and storage in business and first class sections, white wines are often served too warm and red wines too cold.

Coca-Cola advises that the "perfect" temperature to serve its drink is from 1°C to 3.3°C (34 to 38 degrees Fahrenheit) so ice is recommended to lower their temperatures. But usually, cold beverages should be served at 8-10°C. l Several prior art devices are available which attempt to remedy the aforementioned problems. Early attempts to provide a constant chilled beverage temperature included the use of a double walled drinking vessel with a sealed chamber containing a refrigerant, such as water or a gel, e.g. as described in U.S. Patent Nos. 3,680,330 and 2013/0233866 A.

This is normally made of plastic and has to be stored in a refrigerator or freezer for an hour or so before use. The refrigerant is intended to maintain the beverage at a suitable temperature, but of course once the refrigerant turns back from a frozen state to an unfrozen state, the cooling effect is quickly lost. It is also unpleasant to drink wine or beer from a plastic drinking vessel, and condensation on the outer surface is a problem. A foam-moulded outer layer has been used to insulate the drinking vessel. However, using an outer insulation layer to keep a liquid cooler for a longer period of time, in conjunction with the use of a refrigerant results in a very bulky and more expensive drinking vessel.

Similarly, prior art devices exist as inserts for cooling the liquid contents of a bottle which are dipped into the bottle through the open neck, containing a refrigerant, such as water or a gel, e.g. as described in n U.S. Patent Application No. 2006/191238 A1. A disadvantage here is that the cooling device, which has a spindle shape to fit through the neck of the bottle, displaces a certain amount of liquid when dipped into the bottle, so that this amount of liquid has first to be poured out of the bottle, if it is full. A freezable insert for fitting into a stem drinking glass is described in U.S. Patent Application No. 2009/0056368 A1.

Rather than employing a liquid refrigerant, phase change materials (PCMs) can be incorporated into a drinking vessel in order to cool, or warm, the contents of the vessel, by removing or releasing or heat. US Patent Application No. 2013/0221013 A1 describes double-walled drinking vessels, cup holders, jugs and baby’s bottle warmers with a sealed interstitial chamber containing a PCM.

DE102013 114 507 B3 describes a double walled drinking vessel or cup with a sealed compartment containing an organic PCM such as stearic acid mixed with graphite powder in a paste form, for keeping coffee warm. The outer layer of the cup may be an insulating layer with low heat conductivity and the inner layer, or insert, may be of metal or have higher heat conductivity. The cup may be made using a porcelain shell whose hollow interior is filled with a honeycomb structure made of highly conductive material, such as aluminium. This honeycomb structure is then filled with PCM. When the cup is filled with a hot liquid, such as coffee, heat from the coffee is directed straight into the solid phase PCM. This heat, in term, melts the PCM and turns it into its liquid phase. The PCM then retains thermal energy, but without absorbing any more heat, and slowly releases the stored or latent heat back into the coffee. The PCM can be designed to melt at say at 58°C and maintain this temperature, thereby keeping the coffee at that optimum enjoyment temperature for a longer period, following activation of the phase change. However, this is still quite a bulky and expensive drinking vessel to manufacture.

Phase change materials (PCMs) are substances which allow for the storage of heat energy as latent heat and sensible heat. For example, as the substance changes phase from solid to liquid (melts) it is capable of absorbing a large amount of latent heat around its melting point temperature. Conversely, as the substance changes from liquid to solid (solidifies, crystallizes or freezes) it is capable of releasing a large amount of latent around its solidification temperature. A drinking vessel incorporating a PCM, may be regarded as latent heat storage unit. Similarly, a pad containing an inorganic PCM, such as sodium acetate, which becomes warm when it crystallises, may be used as a hand warming pad. Organic PCMs include paraffin waxes, fatty acids, palm oils, esters, glycerine, phenols, etc. which have advantages of being non-toxic, and may be formulated to have melting points within a useful range of from -20°C to +60°C. They may have a bulk structure or may be macro or micro -encapsulated. However, most PCMs suffer from being unsuitable in terms of their thermal properties, i.e. being unable to maintain a drink at a suitable serving temperature, or because they are not food-grade which can cause some health & safety issues when a vessel is broken.

PCMs are sometimes mixed with graphite in powder form, or combined with a graphite foam, for example as described in US Patent No.6, 037, 032, in order to increase the effective thermal conductivity through the volume of the PCM, and so increase the rate in which latent heat is absorbed or released, as compared to bulk PCMs.

Summary of the Invention

In accordance with one aspect of the invention there is provided a fluid containment vessel having a base and an interior volume for containing a fluid above the base; wherein the base comprises a sealed internal void, the internal void being separated from the interior volume of the vessel by an upper wall; the vessel further comprising a temperature control structure situated within the internal void, the temperature control structure comprising: a thermal energy absorbing material comprising water; and a compressible member; wherein said temperature control structure substantially fills said internal void; wherein said compressible member is adjacent and a lower wall of said internal void, such that the thermal energy absorbing material is adjacent the upper wall; and wherein said compressible material is sufficiently large in volume and sufficiently compressible to absorb the thermal expansion arising when said thermal energy absorbing material is cooled to below 0°C.

The fluid containment vessel of the invention has been found to provide for a liquid to be maintained at a target serving temperature for extended periods of 20 to 30 minutes, due to the provision of a temperature control structure that fills the internal void in the base.

The temperature control structure has a water-based thermal energy absorbing material which is also referred to herein for brevity as a phase change material or PCM, although this term should not imply any particular material beyond what is specified in the claims. In use, the vessel is chilled to below the freezing point of the PCM before dispensing a beverage, and when a liquid is added into the vessel’s interior, heat is extracted from the liquid by the PCM to melt the PCM. This extraction of heat serves to cool the liquid or reduce the rate at which the liquid heats up from the environment.

The provision of a compressible member allows for the void to be filled completely while permitting expansion of the PCM when it is frozen prior to use. This gives a significant advantage in allowing glass to be used in the manufacture of the vessel, while avoiding cracking of the glass when the PCM freezes, and also without having any air bubbles in the void which would provide an insulating barrier decreasing the effectiveness of the heat sink properties of the temperature control structure in absorbing heat from the drink.

The compressible member, due to its location adjacent a lower wall of the internal void, also serves to insulate the PCM from the surface on which the base of the vessel rests, increasing the efficiency of the vessel further by ensuring that all or almost all of the latent heat of fusion required to melt the PCM in use is sourced from the contents of the vessel’s interior and not from the environment, although there may be a small amount of conduction through the walls of the base depending on the environment, how the vessel is held, and the construction of the base and the walls of the void.

The compressible member is preferably located and retained below the thermal energy absorbing material in the void and spaced apart from the upper base wall. It is not essential that the compressible member is below all of the thermal energy absorbing material (i.e. small amounts may leak or seep below the compressible member). However, it is preferred if the majority and most preferably substantially all of the PCM is above the compressible member in normal use, so that the compressible member does not act as a thermal barrier between any substantial part of the PCM and the upper wall contacting the liquid within the interior of the vessel.

This can be achieved either by the design of the void (e.g. a dome which only accommodates the compressible member in its lower portion due to decreasing width in the upward direction) or by a structure, such as an open cell foam described herein, which blocks the compressible member from moving out of position. This helps ensure that the surface of the upper wall is in direct contact with the PCM rather than the compressible member. Preferably the compressible member is sandwiched between the PCM and a lower wall of the void.

By saying that the temperature control structure “substantially fills” the internal void, is meant that the structure either fills the void, or the amount of empty space occupied by air is insufficient to cover more than 15%, and preferably more than 5%, of the internal surface of the upper wall in a normal orientation. In this way, the adverse performance of air bubbles, which may insulate the upper wall from the temperature control structure, is minimised. In general, the design and manufacturing process should be optimised to eliminate air bubbles which could travel to the interface with the upper base wall.

In preferred embodiments, the thermal energy absorbing material further comprises a freezing point depressant.

A freezing point depressant enables the freezing point of the PCM to be tailored to specific applications. The freezing point will typically be set to several degrees Celsius below the intended serving temperature, with the optimum temperature offset being determined by the volume of the PCM, the composition of the open cell foam (if present, discussed below), the wall thickness between the void and the interior volume of the vessel, and so on. However, using typical values and materials, it has been found that a target freezing point of between 5°C and 15°C below the desired serving temperature is advantageous, and particularly between 7°C and 12°C degrees below desired serving temperature, even more preferably by 8°C to 10°C.

Preferably, the freezing point depressant is ethyl alcohol. Alternatively, and also preferably, a salt may be used to depress the freezing point. Sodium chloride is particularly useful due to its universal acceptability as a food ingredient and additive combined with its freezing point depressant properties.

A thickening agent may be employed as further discussed herein, and the thickening agent may have both thickening and freezing point depressive properties, in which case the amount of freezing point depressant (if required) can be adjusted accordingly.

Preferably, the freezing point depressant is added in an amount effective to depress the freezing point of said thermal energy absorbing material to between -1.5°C and -10°C.

Preferably, the thermal energy absorbing material comprises a thickening agent.

Such a thickening agent increases the viscosity of the thermal energy absorbing material, and may even bring the material to a gel-like, semi solid or solid composition. By increasing viscosity, the material handling properties are improved during manufacture of the vessel, allowing a controlled volume of the thermal energy absorbing material to be deposited at speed into the internal void, before placing on the compressible member and sealing the base. Furthermore, with increase viscosity, the mobility of any remaining air bubbles is reduced and they can be kept in a position away from the upper wall so that they do not insulate the upper wall from the thermal energy absorbing material.

Preferably, the thickening agent is selected from sodium polyacrylate, food-grade hydrogels, food-grade cellulose ethers, carboxymethyl cellulose (CMC), agar, carrageenans, and natural gums.

The thickening agent is strongly preferred to be food safe, especially when the vessel is a drinking vessel or is intended to contain a liquid for consumption. This ensures that in the event of breakage, cracking or leakage, there is no hazard to health and therefore no concern about the use of this invention, particularly in vessels of glass, ceramic, or other fragile or brittle materials.

Food safe materials are those that have been specified by a public health body as conforming to the standards set for materials coming into contact with food. For example, the European Food Safety Authority maintains a list of food contact materials (FCMs). Similarly, the U.S. Food and Drug Administration regulates a list of approved Food Contact Substances (FCSs). See for example https://www.fsai.ie/publications foodcontactmaterial/ and https://ec.europa.eu/food/sites/food/files/safety/docs/cs fern plastic- guidance 201110 en.pdf for source lists of food safe materials. Preferably, the thickening agent is provided in a volume of between 1% and 20% of the volume of said thermal energy absorbing material.

In certain preferred embodiments, the thickening agent comprises sodium polyacrylate (or polyacrylic acid sodium salt) and is provided in a volume of between 2% and 8% of the volume of said thermal energy absorbing material.

In other preferred embodiments, the thickening agent comprises a natural gum and is provided in a volume of between 4% and 15% of the volume of said thermal energy absorbing material.

Preferably, the temperature control structure further comprises a substantially rigid, permeable structure located in the internal void, the thermal energy absorbing material being distributed within and through the permeable structure.

In this way the permeable structure can assist in efficient heat transfer through the bulk of the thermal energy absorbing material, providing a more efficient heat sink. An open cell foam is particularly good for this, having a very high surface area of contact between the foam material and the thermal energy absorbing material in the foam’s cells.

Preferably, said substantially rigid, permeable structure is formed of a material having a thermal conductivity of at least 10 Wnr¹K¹.

The minimum thermal conductivity level of 10 Wnr¹K ¹ for the substantially rigid, permeable structure refers to the bulk material value. This conductivity helps ensure good thermal distribution and rapid conductivity through the volume of the thermal energy absorbing material. Preferred open cell foams will have thermal conductivity values of in excess of 50 Wnr¹K ¹ and preferably several hundred Wnr¹K¹

Preferably, the substantially rigid, permeable structure is formed of a metal or of graphite.

Preferably the metal is selected from copper, copper alloys, aluminium, aluminium alloys, or steel.

Preferably, said substantially rigid, permeable structure is an open cell foam Most preferably, the foam is a copper foam.

Preferably, said compressible member is disposed between said open-cell foam and a lower wall of said internal void. In cases where the foam substantially fills the upper part of the void, the compressible member may be sandwiched between the foam and a lower wall of the void.

Preferably, the upper wall which separates the internal void from the interior volume of the vessel is configured to project into the vessel interior above its base.

Further, preferably, the upper wall is defined by a protrusion into the interior volume of the vessel, said protrusion being an inverted bulbous protrusion, a hollow finger shaped protrusion, a bell-shaped protrusion, a domed protrusion or an inverted domed protrusion.

Preferably, the base further comprises a lower wall which together with the upper wall seals the internal void.

Preferably, in such embodiments, the compressible member is sandwiched between said open-cell foam and said lower wall.

Preferably, the lower wall comprises a disk which is affixed into place within a recess in the base of the vessel.

Preferably, the internal void has a decreasing width from the base towards the upper wall, whereby the compressible member is held in place adjacent the base by the decrease in width.

Preferably, the upper wall is a generally dome shaped wall extending to the base and defining said decreasing width as it rises towards an apex.

Preferably, the vessel is formed of glass. Glass is strongly preferred by consumers for beverage drinking vessels. However, the use of glass introduces constraints on manufacture and uses that are unique, and that make several prior suggestions for temperature control solutions unsuitable or impractical. The temperature control structure of the present invention however is particularly designed for use in an internal void whose walls are composed entirely of normal, beverage-grade glass.

In a further embodiment in accordance with the invention, the vessel is formed of metal material and has double walls with an evacuable void between the walls.

Preferably the metal material is stainless steel.

There is further provided a method of manufacturing a fluid containment vessel, comprising the steps of: a. providing a vessel body having a base, an interior volume for containing a fluid above the base, and an open internal void below the base, the internal void being separated from the interior volume of the vessel by an upper wall; b. inserting a thermal energy absorbing material comprising water into the internal void in contact with the upper wall; c. placing a compressible member in the internal void outside the thermal energy absorbing material, wherein said; d. sealing the internal void with a lower wall, such that said compressible member and said thermal energy absorbing material are sealed within and together substantially fill said internal void; wherein said compressible material is sufficiently large in volume and sufficiently compressible to absorb the thermal expansion arising when said thermal energy absorbing material is cooled to below 0°C.

The method preferably further comprises the step of inverting the vessel to expose the internal void uppermost prior to step (b).

Preferably, said thermal energy absorbing material further comprises a thickening agent to increase the viscosity thereof and facilitate material handling during steps (b) and (c).

The method may further incorporate steps to result in the features of the vessel of any of claims 1-22.

In another aspect there is provided a fluid containment vessel having a base and an interior volume for containing a fluid above the base; wherein the base comprises a sealed internal void, the internal void being separated from the interior volume of the vessel by an upper wall; the vessel further comprising a temperature control structure situated within the internal void, the temperature control structure comprising a thermal energy absorbing material in the form of a gel having gas bubbles dispersed throughout, the gas bubbles collectively providing a compressible volume to accommodate volumetric changes of the gel material during freeze/thaw cycles; wherein the gel is sufficiently viscous and stable throughout freezing and thawing to retain the gas bubbles in position within the volume of the gel. In a further aspect there is provided a fluid containment vessel having a base and an interior volume for containing a fluid above the base; wherein the base comprises a sealed internal void, the internal void being separated from the interior volume of the vessel by an upper wall; the vessel further comprising a temperature control structure situated within the internal void, the temperature control structure comprising a thermal energy absorbing material comprising water; wherein the lower surface of the base below the temperature control structure is sealed with a flexible membrane permitting expansion and contraction of the thermal energy absorbing material during freeze/thaw cycles.

In yet a further aspect there is provided a fluid containment vessel having a base and an interior volume for containing a fluid above the base; wherein the base comprises a sealed internal void, the internal void being separated from the interior volume of the vessel by an upper wall; the vessel further comprising a temperature control structure situated within the internal void, the temperature control structure comprising a thermal energy absorbing material comprising water; wherein the lower surface of the base below the temperature control structure is sealed with a surface providing a connection to an expansion chamber flexible membrane permitting expansion and contraction of the thermal energy absorbing material during freeze/thaw cycles.

Brief Description of the Drawings

The invention will now be further illustrated by the following description of embodiments thereof, given by way of example only with reference to the accompanying drawings, in which:

Fig.1 is an elevational cross section of a drinking glass in accordance with a first embodiment not currently claimed;

Fig. 2 is a sectional elevation of a drinking glass in accordance with a second embodiment not currently claimed; Fig. 3 is a sectional elevation of a drinking glass in accordance with a third embodiment not currently claimed;

Fig. 4 is a sectional elevation of a temperature control structure for use in a drinking vessel;

Fig. 5 is a sectional elevation of an accessory for a drinking vessel in accordance with of the invention, referred to herein as the fourth embodiment;

Fig. 6 is a sectional elevation of the accessory of Fig. 5 in place in a drinking vessel;

Fig. 7 is a sectional elevation of an accessory for a drinking vessel in accordance with the invention (fifth embodiment);

Fig. 8 is a sectional elevation of the accessory of Fig. 7 in place in a drinking vessel;

Fig. 9 is an exploded view of an accessory for a drinking vessel in accordance with the invention (sixth embodiment);

Fig. 10 is an exploded view of an accessory for a drinking vessel in accordance the invention (seventh embodiment);

Fig. 11 is a perspective view of the accessory of Fig. 9 or Fig. 10 and a drinking vessel when the accessory is being inserted into a drinking vessel;

Fig. 12 is a perspective view of the accessory and drinking vessel of Fig. 11 when the accessory is inserted and secured;

Fig. 13 is a sectional elevation of the accessory and drinking vessel of Fig. 11 at an intermediate stage during insertion of the accessory;

Fig. 14 is a sectional elevation of the accessory and drinking vessel of Fig. 11 when the accessory is inserted and secured;

Fig. 15 is a comparative plot showing the effect on beverage temperature versus time of a drinking vessel as described herein as compared with a conventional drinking vessel under different experimental conditions;

Fig. 16 is a comparative plot showing the effect on beverage temperature versus time of a drinking vessel as described herein as compared with a conventional drinking vessel under different experimental conditions;

Fig. 17 is a comparative plot showing the effect on beverage temperature versus time of a conventional plastic drinking vessel fitted with an accessory according to the invention as compared with a conventional plastic drinking vessel without the accessory; Fig. 18 is a sectional elevation of a drinking glass in accordance with a fourth embodiment not currently claimed;

Figs. 19 and 20 are enlarged views of the base of a drinking glass in accordance with a fifth embodiment not currently claimed;

Figs. 21 and 22 are sectional elevations of a drinking glass in accordance with a sixth embodiment not currently claimed;

Fig. 23 and 24 are sectional elevations of accessories for a drinking vessel in accordance with the invention, referred to herein as the fourth embodiment;

Fig. 25 and 26 are sectional elevations of further accessories for a drinking vessel in accordance with the invention;

Fig. 27 shows two comparative temperature plots over time, along with a third line representing the percentage improvement achieved by the invention;

Fig. 28 is a sectional elevation of a further embodiment of a fluid containment vessel in accordance with the invention;

Fig. 29 is a sectional elevation of the fluid containment vessel of Fig. 28, being filled with a thermal energy absorbing material; and

Fig. 30 is a sectional elevation of the fluid containment vessel of Fig. 28, ready for use.

Detailed Description of Preferred Embodiments

In Fig. 1 there is indicated, generally at 10, a drinking vessel of a tulip shape typically used for serving beer or cider (though of course it is by no means limited to such applications).

The vessel is made of glass, the glass shape having a generally cylindrical sidewall with a tulip profile, and a concave (when viewed from below) domed upper base wall 14, which together define a vessel interior 16, shown here filled with liquid.

Below the upper base wall 14 and sealing the base of the vessel 10 is a disk 18 which may be of a flexible or compliant sealing material such as a setting or curable resin. The disk may also be of glass, plastic, or any other suitable material which bonds to the main glass body. The disk 18 provides a seal and a flat base for the glass to rest upon. Within the base, between the disk 18 and the upper base wall 14 is a sealed internal void 20 having a volume of about 30 ml, filled with a temperature control structure 22 which will be described in detail below. At a minimum the temperature control structure has a thermal energy absorbing material (or PCM) comprising water, and a compressible member, the temperature control structure filling or substantially filling the internal void.

The temperature control structure is designed to absorb heat efficiently from the liquid in the interior volume of the glass, with this effect being increased by the domed shape which increases the surface area of liquid in contact with the upper base wall’s top surface.

Prior to pouring beer, the glass is kept in a freezer or refrigerator to allow a thermal energy absorbing material in the temperature control structure to change its phase from liquid to solid (freeze or solidify). When beer is poured into the glass, the dome is completely covered. The cooling effectiveness of the temperature control structure will depend on the temperature of the beer, the temperature of the ambient environment, the initial glass temperature and the volume of liquid in the glass, as well as the manner in which it is held.

However, using the compositions and structures disclosed herein, with internal void volumes of about 30 ml in a pint glass, under normal conditions (i.e. commercial bar freezers, beer served at 3.5°C, ambient temperatures of 20°C), it was found that the glass of Fig. 1 was effective to maintain the beer temperature below 4°C even after 30 minutes, whereas a conventional glass taken from the same freezer exhibited a rise in temperature to about 12°C over the same period. These experimental results are discussed further below.

The thickness of the upper base wall between the beverage and the internal void should be as thin as possible within the constraints of manufacturing processes and the strength of glass to avoid its brakeage in normal use. However, a wall thickness of 2-3mm is achievable and provides the results discussed above.

While the glass of Fig. 1 may be conventional glass used in beverage applications, one can employ glasses having a higher thermal conductivity than a typical glass to reduce thermal resistance between beverage and the temperature control structure and thereby increase heat transfer rates.

In Fig. 2, indicated generally at 24, is a second embodiment of drinking vessel, in which like parts are designated with like reference numerals as in Fig. 1. However, in place of the domed upper base wall 14 of Fig. 1 , the vessel 24 has a bell-shaped upper base wall 26 forming a more pronounced protrusion into the interior volume 16. The bell-shaped protrusion is suited to providing more intimate indirect contact between the material inside the internal void and the liquid contents of the glass. Preferably, the dome of the Fig. 2 embodiment extends about one third the overall height of the glass, but it may be configured as a finger extending to about three-quarters the height of the glass. This design prevents complete mixing of a fluid in the lower and upper part of the glass resulting in a cooler fluid at the end of drinking than in the glass in Fig. 1. The same design principle is presented for the accessory in the example 3.

In Fig. 3 there is indicated generally at 28 a third embodiment, constructed entirely of glass, having a tapered straight sidewall 30, a flat upper base wall 32, and a flat glass lower base wall 34 sealing a frusto-conical internal void 36 within the base 38 of the glass.

While the walls are all shown as having equal thickness, in practice the sidewalls of the main liquid-containing volume may be thinner than the walls of the base. For example, one possible design (whether of the glass of Fig. 1 , 2 or 3) has main sidewalls of 1 mm to 3.5 mm thickness, an upper base wall of 2 mm to 3.5 mm thickness, and sidewalls around the base of 4 mm to 7 mm thickness. The thickness of the lower base wall or of the disk sealing the base can be from 1 mm to 8 mm depending on the material used (as this may be glass or some other sealing material).

The temperature control structure filling the internal void 36 of Fig. 3 can be seen to have an upper component 44 and a lower component 46 which will now be described in further detail.

Fig. 4 shows the temperature control structure used in Fig. 3, which may be adapted with suitable changes in shape for use also in the vessels of Figs. 1 and 2. The upper component 44 is an open cell copper foam member 48 shaped to occupy most or all of the upper portion of the internal void and fit within whatever shape is chosen for the upper base wall’s lower surface. Thus, while a flat top is specified in Fig. 4, this would be a domed shape for Fig. 1 and a bell shape for Fig. 2.

It is not necessary that the copper foam member be in close contact with the upper base wall, though it is preferred; the main function of the copper foam is to assist in heat transfer through the volume of liquid with which it is saturated. Indeed, it is not essential that the foam be used at all, though it does provide optimum heat transfer efficiency.

The open cell foam is saturated with a thermal energy absorbing material 50 that is distributed within and through the cells of the open-cell foam. The material 50 comprises water and a thickening agent so as to provide a viscous liquid, or a gelatinous or semi-solid material that can be absorbed by the open cell foam.

The lower member 46 of the temperature control structure is a compressible member 52 that ensures that the internal void is completely filled and nevertheless permits thermal expansion of the material 50, particularly when the material 50 is cooled down to and below its freezing point. The skilled person will be aware that water expands by approximately 9% as it changes its phase to ice below 0°C. The material 50 may have a different freezing point due to the presence of the thickening agent and optionally a freezing point depressant, but it will nevertheless exhibit similar amounts of expansion due to the water content.

The open cell foam used in the specific example shown here is copper with a 95% porosity and 10 pores per inch. Thus, if the volume of the copper foam body is 20 ml (a typical value for use in the base of a drinking glass), this will contain 1 ml of copper, the remaining volume being the voids.

The thermal energy absorbing material 50 is with a food-grade hydrogel solution consisting of (in one embodiment used in experimental results discussed below): 21.5 ml water, 5.5 ml alcohol solution (40% ethyl alcohol, 60% water), 1 ml sodium polyacrylate (polyacrylic acid sodium salt crosslinked, FCM substance No. 1015, CAS No. 0009003-04-7), 1 ml graphite powder.

The compressible member 52 is a disk of polyurethane 1.5 mm thick, 50 mm in diameter (therefore with a volume of just under 3 ml). Other compressible members may be used provided that they provide sufficient compressibility (e.g. 9% or more) and that, for applications where the vessel is to be used for beverages, they are food-grade or food safe materials.

The optional addition of graphite powder assists in thermal conductivity through the material.

Some other compositions for the thermal energy absorbing material are shown in Table 1 below, with the just-described material identified as composition #1. Values in Table 1 are expressed as volumes of additive per 1 ml of water/alcohol. The proportion of alcohol in the water can be varied in order to adjust the intended freezing point. Thus, in the material described above, there is 21.5 ml water plus 5.5 ml of 40% alcohol solution giving 27 ml water/alcohol in the composition. This 27 ml is composed of 0.4 * 5.5 = 2.2 ml alcohol, and 21.5 + (0.6 * 5.5) = 24.8 ml water. The sodium polyacrylate (polyacrylic acid sodium salt) is added in an amount of 1 ml per 27 ml water/alcohol, or 0.037 ml per 1 ml water/alcohol, which is the value in Table 1. The same composition, with a different alcohol concentration, could be employed to achieve a different freezing point. Table 1

The inventors have found that excellent cooling results are found when the thermal energy absorbing material or PCM is adjusted to have a freezing point about 8.5°C below the desired serving temperature of the beverage.

Table 2 below shows, for different PCM volumes (25, 30, 35, 40, 45 and 50 ml), the required volume of 40% ethyl alcohol solution that is required to achieve a particular PCM freezing point, and the corresponding optimum serving temperature associated with such a PCM. Thus, for a 25 ml PCM volume, with a desired serving temperature of 2°C, the target PCM freezing point of -6.5°C is achieved with 6.5 ml alcohol solution in the 25 ml PCM volume. Similarly, for a 40 ml PCM volume and desired serving temperature of 5°C, the target PCM freezing point of -3.5°C is achieved with 5.6 ml 40% alcohol solution in the 40 ml PCM volume. The skilled person will be able to adjust the values accordingly for other PCM volumes and alcohol solution concentrations to achieve the same differential of 8.5°C, or indeed adapt this to achieve an alternative differential between serving temperature and PCM freezing point. Table 2

Fig. 5 shows, generally at 54, an accessory for use with a drinking vessel. The accessory 54 takes the form of an insert body member having a domed top surface 56 and a flat underside 58, which together define a sealed internal void 60. The domed top surface may be made of food-grade plastic, of aluminium or of glass, and the flat underside may be made of food- grade plastic, of glass, or sealed with aluminium foil.

The void 60 has a thermal energy absorbing material or PCM 62 within it, which comprises water. In its simplest form, the entire volume of the internal void is taken up by water. The PCM may also include a thickening agent such as natural gum, carboxymethyl cellulose or sodium polyacrylate. The compositions given in Table 1 and 2 may all be used as the thermal energy absorbing material.

Optionally, the void may include an open cell foam structure within and through which the thermal energy absorbing material is distributed. It may also include thermally conductive particles such as graphite, copper or aluminium.

It may include a freezing agent depressant, such as alcohol, salt or natural ester oils extracted from soya bean or corn as previously described.

In particular, the temperature control structure of Fig. 4 may be incorporated into the internal void of the Fig. 5 device. Fig. 6 shows the accessory of Fig. 5 in place in the bottom of a drinking vessel 64, with the flat underside secured to the base 66 of the vessel by a food-safe adhesive 68. It can be inserted and adhered immediately before use (in which case the accessory alone only needs to be frozen) or prior to use including when the vessel is being manufactured or as a separate fitting or retrofitting operation. When it is secured in advance, then in preparation for use the vessel with the accessory in situ is frozen before the beverage is poured.

Fig. 7 shows a further accessory, indicated generally at 72, in perspective view from below. The accessory is generally similar in shape to that of Fig. 5 in that it has a domed upper surface 56 and a flat underside 58 defining an internal void (not shown in Fig. 7). However, it differs in the addition of a food-grade silicone skirt 69 which has an annular shape with an internal diameter less than that of the base 58 and an external diameter greater than that of the base, so that it extends beyond the periphery 70 of the insert body member.

In use, as shown in Fig. 8, the accessory 72 is inserted into a glass with an internal diameter which is greater than that of the insert body but less than the external annular diameter of the silicone skirt 69. This has the effect of displacing the skirt upwardly as the accessory is slid downwardly towards the base 66 of the glass 64. The skirt therefore conforms to the internal sidewall 74 of the glass and resists being displaced, securing the accessory 72 in place at the bottom of the glass.

The insertion can be permanent, or it can be removable. The accessory can be removed using a purpose designed pincer or suction cup. Alternatively, a pull tab can be provided on the top surface or on the skirt to assist in manual removal. Further alternatively, the skirt can be made long enough to allow a user to grasp and displace it from engagement with the glass.

In Fig. 9 an exploded view of an accessory 75 is seen, showing a plastic dome 76, a plastic base 78 which seals to the dome, and a volume of thermal energy absorbing material 80 which is contained within the assembled dome. As previously described, the thermal energy absorbing material may (but need not) be supplemented with an open cell foam, with a freezing point depressant, with graphite powder and so on.

Fig. 10 shows a similar exploded view of an alternative internal construction for accessory 75. The embodiment of Fig. 10 differs from that of Fig. 9 in the inclusion, below the thermal energy absorbing material, of a compressible member 82. While a compressible member is advantageous, it may not always be necessary, particularly when the dome 76 and base 78 are made of materials with sufficient flexibility to absorb thermal expansions and compressions of the thermal energy absorbing material.

A preferred embodiment takes the form generally shown in Fig. 9, with the dome 76 and the base 78 both made of silicone 1 mm thick. The thermal energy absorbing material is a 5% aqueous solution of sodium chloride, and there is no copper foam or thickening agent. The base is sealed to the dome with a neodymium magnet embedded within the base as will be discussed further below.

The thermal energy absorbing material may be of alternative composition, such as a mixture of water and a thickening agent such as carboxymethyl cellulose. A preferred ratio CMCihhO is in the range from 3:97 to 15:85, more preferably 5:95 to 10:90, with a particularly preferred range of 6:94 to 8:92. To this, salt or alcohol may optionally be added as a freezing point depressant.

In the accessories of Figs. 9 and 10, the base 78 is provided with magnetic properties. For example, a magnet may be secured to the top or bottom surface of the base member or the base member may itself be magnetic. Alternatively, the base member may be made of, or may be provided with, a material that it attracted to a magnet.

As seen in Fig. 11 , the accessory 75 may be inserted, similarly to Figs. 6 and 8, into the interior of a drinking vessel 84, flat side 78 downwards. A disk 86 is provided externally off the drinking vessel and is adapted to fit into a recess 88 on the underside of the drinking vessel 84, as best seen in Fig. 12. The disk is magnetically attracted to the base 78. Thus, the disk may be a magnet, or may have a magnet provided on it, or it may be made of, or may be provided with, a material that it attracted to a magnet in the base 78.

A preferred construction incorporates a small, strong, neodymium magnet in the base 78, and has a disk made of steel, nickel, or other ferromagnetic material.

It has been found that with the construction shown, having an elastomeric body construction defining the internal void, and a metallic or other magnetically attractive member on the base, the accessory has a differential buoyancy whereby it tends to orient itself with the base downwards when immersed in a fluid. The materials are chosen to ensure an overall negative buoyancy in water or liquids of similar density, so that it can be dropped into a liquid and it will sink down in the correct orientation to land on the base with the disk against the base. The buoyancy characteristics are preferably chosen so that any additional positive buoyancy arising from bubbles adhering to the accessory (such as when it is dropped in beer, cider, sparkling wine, or any other carbonated or effervescent liquid) is overcome and the net buoyancy is negative.

In Fig. 12, the accessory (not shown) is in place at the bottom of the vessel 84 and the disk 86 is in place in the recess 88. Due to the magnetic attraction between two magnetically attracted members, one in or on the disk and the other in or on the base member 78, the accessory is held in place. Figs. 13 and 14 show the insertion of the accessory 75 and the final configuration, respectively, in cross section. Obviously, the magnetic attraction must be sufficiently strong through the base of the vessel as to hold the accessory in place during normal serving and drinking of a beverage. Preferably it is of a strength that also permits the disk to be detached from its magnetic engagement relatively easily when it is desired to remove the accessory for cleaning or for reuse.

Furthermore, there is a combination of two above inventions: a fluid containment vessel having an internal void which projects into the vessel interior containing a fluid (see Fig 1 or Fig 2) and the insert body member (see Fig 5) adapted for insertion into the drinking vessel internal void. The insert body member, in this combination, is placed in the silicone skirt (see Fig 8) and provides a seal at a flat base for the vessel to rest upon. The internal annular diameter of the silicone skirt (Fig 8) is slightly less than the external diameter of a base of the glass. The skirt therefore conforms to the external sidewall of the glass (Fig 1) and resists being displaced, securing the insert body member in place at the internal void of the glass.

It will be appreciated that the embodiments of Figs. 9-14 are particularly advantageous in permitting the rapid and easy insertion and removal of the accessory, as well as being commercially attractive in providing an external surface 90 of the disk that is very well suited to branding and advertisement purposes.

Example 1

The tulip glass of Fig. 1 was constructed with a temperature control structure as in Fig. 4 in the internal void in the base. The glass was a pint glass (568 ml internal volume). The thickness of the upper base wall was 3 mm.

The dome was filled (from its underside, with the glass inverted) with 29 ml of thermal energy absorbing material, made up of 21.5 ml water, 5.5 ml 40% alcohol solution, 1 ml polyacrylic acid sodium salt, and 1 ml graphite powder. This material had a freezing point of - 5°C.

A 20 ml block of copper open cell foam was also inserted into the dome (porosity 95%, 10 pores per inch, copper volume 1 ml) such that the foam was saturated with and fully immersed in the thermal energy absorbing material, and bringing the overall volume to 30 ml. It will be noted that the volume of the open cell foam (20ml) was less than the volume of thermal energy absorbing material and so there was excess fluid within the dome with the foam being completely immersed.

Then, while the glass was still inverted, a 3 ml polymeric foam disk (ca. 1.5 mm thick, 50 mm diameter) was placed and then the base was sealed to compress the disk and seal the internal void. At this point the internal void, which was constructed with a volume of 33 ml, was completely filled with no air bubbles.

The following external conditions were established: room temperature, 21 °C; initial temperature of the empty beer glass when taken from a freezer, -15°C; initial temperature of control beer glass not taken from a freezer, 21 °C; serving temperature of beer, 3.5°C.

A typical drinking habit was imitated in such a way that after every 1 minute a 20 ml volume of beer was removed from a glass, and the remaining beer was mixed every 5 minutes. This was repeated for 20 minutes, after which time no further beer was removed, but the remaining 100 ml allowed to stand until 30 minutes.

Fig. 15 shows four temperature curves of beer recorded using this protocol for the glass of Fig. 1 as has just been described and also for a conventional tulip pint glass (i.e. without any temperature control structure).

The line 121 in Fig. 15 shows the results for glass of Fig. 1, which was taken from the freezer before being filled with beer. It will be seen that the beer temperature was kept remarkably stable and remained in the range 2.8°C - 3.6°C throughout the 30 minutes.

Line 122 shows a comparative result for the conventional tulip pint glass under the same conditions. It can be seen that while there is a temporary cooling effect due to the chilled glass absorbing heat from the beer for the first five minutes, the effect is then lost and the beer heats up linearly from 3.4°C at 5 minutes to 11.8°C at 30 minutes.

Comparing further to line 123, this shows the temperature curve for the conventional pint glass without it having been placed in the freezer beforehand. The beer heats up throughout the process, having initially risen to 6.3°C at 5 minutes, and then continuing to rise up to 14.5°C at 30 minutes.

Notably, the slopes of lines 122 and 123 are almost identical after the initial chilling/warming over the first five minutes due to the starting temperature of the conventional glass. In other words, both lines show an almost identical linear increase in temperature from 5 to 30 minutes (+8.4°C for the frozen glass, +8.2°C for the room temperature glass).

Finally, to demonstrate the effect of body temperature on the warming, line 124 shows the temperature curve for the same conditions as line 123, but with the glass held in hand throughout. The temperature rises linearly over 30 minutes from 5.7°C at 5 minutes to 19.0°C at 30 minutes. From a comparison with line 123, it can be seen that the slope of the line increases, so that the body temperature seems to add about 0.75°C per five minutes. It can be seen that the ambient temperature causes an 11°C rise over the 30-minute period while the body temperature adds a further 5.5°C.

The experimental results presented in Fig. 15 prove that the invented glass with its temperature control structure is far superior to a standard glass in ensuring that beers can be consumed at their optimum serving temperatures. The effect of chilling a conventional glass is minimal in comparison.

Example 2

A tulip pint glass was again made as in example 1 and as shown in Fig. 1, but with a different temperature control structure in the internal void. The dome was filled with 30 ml of a thermal energy absorbing material comprising 22.5 ml water, 5.5 ml 40% alcohol and 2 ml thickening agent (gum tragacanth). This material, which had a freezing point of -4.5°C, was then covered with 3 ml polymeric foam (c.a. 1.5 mm thick, 50 mm diameter) and sealed as before

The following external conditions were established: room temperature, 20°C; initial temperature of the empty beer glass from the freezer, -15°C; initial temperature of the empty beer glass not taken from a freezer, 21 °C; serving temperature of beer, 4°C.

Fig. 16 shows three comparative temperature plots overtime, along with a fourth line representing the percentage improvement achieved by the invention. The same protocol was used in these measurements as in example 1 to imitate a typical drinking habit both for the glass with temperature control structure and for the reference tulip pint glass. For each of the three experimental measurement curves plotted in Fig. 16, the glass was not held in the hand, i.e. it was left on the bench throughout.

Line 221 is the plot of the glass having the gum tragacanth temperature control structure just described, when taken from the freezer. It can be seen that this glass causes the temperature to first drop to 3.2°C at five minutes and then very slowly rise to 5.1°C at 30 minutes. Thus, the beer remained within 1.1 °C of the serving temperature throughout. The slight difference with respect to the performance of example 1 may be due to the different thickening agent, or the absence of the copper foam, but the performance is nevertheless excellent in maintaining the beer at the desired temperature range for an extended period.

Line 222 shows the performance of the conventional glass taken from the freezer, and this is almost identical (as would be expected) to the results from experiment 1 , giving an initial cooling effect which had disappeared by 5 minutes, and then a steady linear rise to 11°C. Line 223 shows the performance of the conventional glass, when not chilled beforehand in a freezer. The performance is again almost identical to that of the equivalent experiment in Example 1, although the final temperature is slightly lower (12.5°C versus 14.5°C). The difference can be accounted for by the slight difference in ambient room temperature.

Line 224 shows a measure of the improvement achieved by the invention versus the conventional glass taken from the freezer, expressed as a percentage. The calculation of the percentage value is made by comparing the temperature values (degrees above 0°C being the base point) and determining at each measurement time how much lower the value on line 221 for the glass with temperature control structure was when compared with the corresponding value for the conventional glass on line 222. So for instance at 5 minutes, the value on line 221 (3.2) was 20% lower than that on line 222 (4.0). At 15 minutes, the value on line 221 (3.7) was 43% lower than the value on line 222 (6.5). At 30 minutes, the value on line 221 (5.1) was 54% lower than the value on line 222 (11.0).

Example 3

In this example, an accessory was made according to Fig. 9. A plastic dome with a plastic base, providing a sealed internal void volume of 33 ml, was filled with a temperature control structure having three components. First, a 20 ml volume of copper open cell foam (porosity 95%, 10 pores per inch, copper volume 1 ml) was added. Then a thermal energy absorbing material comprising 30 ml water and 2 ml polyacrylic acid sodium salt was added and this was absorbed into the pores of the copper foam, with the copper foam being fully immersed in the solution before the dome was sealed with the base. The accessory was then placed in a freezer.

The following external conditions were established: room temperature, 21 °C; initial temperature of accessory on being taken from freezer, -15°C initial temperature of an empty plastic cup, 21 °C; serving temperature of beverage 9°C. A typical drinking habit was again imitated using the same protocol as in Examples 1 and 2.

Fig. 17 shows comparative temperature curves for the same plastic cup, with and without the accessory having been placed in the base before pouring the beverage. In neither case was the cup held in the hand.

Line 321 shows the temperature curve when the accessory is in the plastic cup. The beverage remains at a temperature between 8.7°C and 9.7°C over the full 30-minute period. Line 322 shows the temperature curve for the same cup and beverage without the accessory, and it can be seen that there is a linear temperature rise from 9°C to 14°C over the 30-minute period.

Fig. 18 shows a further embodiment, similar to Fig. 1 , in which corresponding elements have the same reference numerals but incremented by 400 (thus drinking vessel 10 becomes drinking vessel 410, etc.).

The embodiment of Fig. 18 differs from that of Fig. 1 in that a different temperature control structure 422 is employed. The sealed internal void 420 is completely filled with a gel 422 having dispersed throughout numerous miniature gas bubbles. The gel is sufficiently viscous and stable during freeze/thaw cycles to retain the bubbles in position within the volume of the gel.

The aggregate volume of gas provided by the bubbles is sufficient to accommodate the expansion and contraction of the gel during freezing and thawing in use. In this way, a separate compressible member can be dispensed with, and the compressibility (or expansibility) of the gas acts to absorb volumetric changes in the gel.

In one embodiment, the gel may be made by dissolving sodium polyacrylate in of deionised water to form a viscous, semi-solid gel. During dissolution of the polyacrylate, gas bubbles are introduced, or a foaming agent is added to create a foam with entrained gas bubbles, and the bubbles are entrapped as the gel solidifies.

Fig. 19 shows a detail of a further embodiment, the view being an enlarged view of the base of a glass 500.

In the embodiment of Fig. 19, the temperature control structure 502 comprises a 5% sodium chloride solution in water providing the freezing point depression of -3°C, with no thickening agent and no compressible member. Instead of a compressible member to absorb freezing- induced expansion, the bottom of the internal void 504 is sealed with a flexible membrane 506 of silicone which is bonded to the glass within a recess 508 in the base.

The flexible membrane 506 can flex upwards or downwards to accommodate volumetric changes in the temperature control structure 502. In this way the temperature control structure need not include a compressible member (although such a member could equally be included in this embodiment if desired to take up some of the expansion or contraction, with the membrane’s movement providing a contribution also). The embodiment of Fig. 19 can therefore have a temperature control structure in the form of a thermal energy absorbing material (like water with or without a thickening agent, and with or without a freezing point depressant), and can be implemented with or without a metal foam structure. It can be seen that the perimeter 510 of the glass at the base extends below the membrane when the membrane is in its neutral or relaxed, flat, configuration as shown in Fig. 19.

Referring to Fig. 20, when the membrane is displaced downwards due to freezing of the aqueous saline solution 502, the extended perimeter 510 provides a space within which the movement of the membrane 506 is accommodated without risk of the glass upsetting or becoming unstable.

Figs. 21 and 22 shows a further embodiment of glass vessel according to the invention. In Fig. 21 , the main glass body 600 is shown. It is generally similar to the glass body of Fig. 1 , and has a vessel interior 602 defined within a generally cylindrical, tapering sidewall 604 and a domed base wall 606. The thickness of the base wall 606 at dimension A is 5.2 mm in this embodiment.

Below the base wall a domed space 608 is defined for an internal void to contain a temperature control structure (not shown in Fig. 21). The lower surface of the base wall 606 is 27.5 mm (dimension B) above the perimeter 612 of the base where it contacts the surface on which the glass rests. It can be seen that the domed underside of the base wall 606 terminates above a recess 612 which is adapted to receive a sealing disk (not shown) of glass and thereby seal the generally hemispherical internal void.

Fig. 22 shows the finished glass 600 after the internal void has been sealed by a glass disk 614 of thickness 3 mm and diameter 62 mm, which is bonded using a UV-curable adhesive into the recess 612 (Fig. 21).

A disk 616 of expanded polyethylene foam (diameter 55mm, thickness 5mm - not shown to scale) is positioned immediately adjacent glass disk 614 within the internal void. This disk 616 acts as a compressible member as previously discussed herein. It can be seen that, due to the decreasing width of the internal void in the upward direction defined by the dome shaped underside of the base wall 606, the disk 616 is held in position and is not free to move within the internal void.

Above the foam disk 616 is a volume of thermal energy absorbing material, which in this case is a 5% aqueous solution of sodium chloride. In this embodiment, there is no thickening agent or copper foam, but the thermal characteristics of the glass are nevertheless excellent due to the heat sink effect provided when the thermal energy absorbing material is frozen before use. It should also be noted that the thicker base wall in this embodiment (preferably of between 4 and 7 mm thickness, more preferably 4.5 to 6.5 mm, most preferably 5 to 6 mm) contributes to the heat-absorbing qualities of the glass, the thermal energy absorbing material keeping the base wall cold as it absorbs heat from a beverage in the vessel interior. An alternative composition for the thermal energy absorbing material is a solution of carboxymethyl cellulose in water. A preferred ratio CMCihhO is in the range from 3:97 to 15:85, more preferably 5:95 to 10:90, with a particularly preferred range of 6:94 to 8:92. To this, salt or alcohol may optionally be added as a freezing point depressant.

The glass of Fig. 22 is manufactured by creating the main glass body shown in Fig. 21 using conventional glass manufacturing techniques. This body is then inverted and the thermal energy absorbing material 618 is filled with a precise volume into the void 618. The filling volume is chosen so that when the foam disk 616 is added, it is flush with the perimeter of the domed sidewall where it meets the recess 612, i.e. the internal void is exactly filled with negligible amounts of air remaining.

Then a UV curable adhesive is applied to the recess, the glass disk 64 is positioned in the recess, and the adhesive is cured to bond the disk to the main glass body and seal the internal void.

Figs 23 and 24, and Figs. 25 and 26 respectively show two accessories with a special design to prevent complete mixing of a fluid in the lower and upper parts of a drinking vessel resulting in a much colder fluid at the end of drinking.

In Figs. 23 and 24 the accessory takes the form of an insert body member 700 having an external cylindrical surface, an internal truncated circular conical surface, flat top and base, which together defined a sealed internal void. Fig. 23 shows a cross-section in the horizontal plane, and Fig. 24 a cross-section in the vertical plane.

The internal 705 and external 710 surfaces may be made of food-grade plastic, of aluminium or of glass, and the flat top 715 and underside 720 may be made of food-grade plastic, of glass, or sealed with aluminium foil. The void 725 has a thermal energy absorbing material or PCM within it, which comprises water. When the accessory is placed in a drinking vessel filled with a beverage (not shown) the internal truncated circular conical volume 730 is filled with the beverage fluid. The height H of the accessory can be adjusted to increase a volume of beverage fluid which is trapped in the internal truncated circular cone 730. The conical shape inhibits mixing of a fluid in the lower and upper part of a drinking vessel and at the same lowering its temperature below a serving one.

Figs. 25 and 26 show a similar accessory 750 in the same horizontal and vertical cross sections respectively. Like numerals denote like parts as in Figs. 23 and 24. This accessory 750 has multiple internal truncated circular conical volumes 730 which due to their smaller volumes further reduce a temperature of fluid at the end of drinking. Example 4

In this example, an accessory was made according to Figs. 23 and 24. A plastic cylinder with the internal empty volume of a circular truncated cone and a plastic top and base, providing a sealed void volume of 30 ml, was filled with a temperature control material having three components: 22.5 ml water, 5.5 ml 40% alcohol and 2 ml thickening agent (polyacrylic acid sodium salt). This material, which had a freezing point of -4.5°C, was then covered with 1.5 mm thick polymeric foam and sealed as before. The accessory was then placed in a freezer.

The following external conditions were established: room temperature, 21 °C; initial temperature of accessory on being taken from freezer, -15°C initial temperature of an empty plastic cup, 21 °C; serving temperature of beverage 4°C. A typical drinking habit was imitated in such a way that after every 2.5 minute a 50 ml volume of beer was poured from a glass. This was repeated for 25 minutes, after which time no further beer was removed, but the remaining 50 ml allowed to stand until 30 minutes. The total volume of beer in the plastic cup was 500 ml.

Temperature measurements were taken to establish the temperatures of beverage inside and outside the circular truncated cone, respectively when the accessory was in a plastic cup. The temperature of beverage remained below serving temperature 4°C over the full 30- minute period with the temperature of beverage inside the circular truncated cone below 3.2° reaching the lowest point of 1 6°C at the end. After 20 min beverage filled only the circular truncated cone. Corresponding measurements of the temperature for the same cup and beverage without the accessory exhibited a linear temperature rise from 4°C to 10.9°C, over the 30-minute period. The temperature difference of the last 50 ml of beverage in the cup with and without the accessory is more than 9°C. This special design of the accessory with the internal truncated circular conical volume prevents complete mixing of a fluid in the lower and upper part of the cup resulting in a much cooler fluid at the end of drinking.

This demonstrates the effectiveness of the accessory in allowing the beverage to remain at its serving temperature throughout the 30-minute experimental period.

While the above examples and embodiments focus on beer glasses it will be appreciated that the invention is in no way limited to this specific application. Wine glasses, other beverage glasses and cups may all incorporate the temperature control structures disclosed herein in their bases, or may receive the accessories disclosed herein. While intended primarily for drinking vessels such as glasses and cups, the invention may also be applied to other fluid containment vessels such as jugs and bottles. Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiment shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

Example 5

In this example, an insulating storage vacuum vessel and an accessory made of aluminium according to Fig. 5 were used together as complementary techniques to achieve a suitable drinking temperature of cold beverages for a long period of time. The accessory of a sealed void volume of 64 ml which was filled with a phase change material having three components: 60 ml water with 2% by weight of sodium chloride which had a freezing point of -1.5°C and 4 ml thickening agent (polyacrylic acid sodium salt). The accessory was then placed in a freezer.

The following external conditions were established: room temperature, 21 °C; initial temperature of accessory on being taken from freezer -15°C, initial temperature of fluid 8°C. The total volume of fluid (water) in the insulating storage vacuum vessel was 355 ml. Temperature measurements were taken to establish the temperatures of water for two cases: with and without the accessory placed in the insulating storage vacuum vessel.

Fig. 27 shows two comparative temperature plots overtime, along with a third line representing the percentage improvement achieved by the invention. Line 421 is the plot of water in the vacuum vessel having the PCM temperature control structure just described. It can be seen that the temperature of water in the vacuum vessel drops by 5°C to around 3°C at 50 minutes, stays at this value for 1.5 hr and then very slowly rises to 15.5°C at 18 hrs. Moreover, the water remained below the initial temperature of 8°C for 6.5 hrs. Line 422 shows the performance of the vacuum vessel without the temperature control structure (PCM), showing a steady linear rise from the initial temperature of 8°C to 18°C at 18 hrs.

The temperature of 15.5°C is reached at 10 hrs so 8 hrs earlier than in the vacuum vessel with the PCM. Line 423 shows a measure of the improvement achieved by the invention versus the vacuum vessel without the PCM, expressed as a percentage. The calculation of the percentage value is made by comparing the temperature values (degrees above 0°C being the base point) and determining at each measurement time how much lower the value on line 421 for the vacuum vessel with temperature control structure was when compared with the corresponding value for the vacuum vessel without the PCM on line 422. So for instance at 1.3 hours, the value on line 421 (2.6°C) was 74% lower than that on line 422 (10.0°C). At 7 hrs, the value on line 421 (8.4°C) was 41% lower than the value on line 422 the end (18 hrs), the value on line 421 (15.6 C) was still lower by 13% than the value on line 422 (18.0°C).

This demonstrates the effectiveness of the accessory in allowing the water to stay below its initial temperature for the period of almost 7 hours.

While the above example focuses on one particular vacuum vessel the same approach can be implemented with other vacuum vessels of different volumes and with different initial temperatures of liquids. Having a PCM inserted in a vacuum vessel will lower the temperature of liquids allowing for keeping them cold much longer than in a vacuum vessel without the PCM insert.

In Fig. 28 there is indicated generally at 800 a sectional elevation of a further embodiment of a fluid containment vessel in accordance with the invention. The drinking vessel 800 is made of stainless steel and has a generally cylindrical shape, with two side walls 801, 802 which enclose an evacuable void 803, and a concave (when viewed from above) upper base wall 804, which together define a vessel interior 805 into which a beverage may be poured, in use. The upper base wall 804 defines an inverted domed protrusion 806 into the vessel interior 805.

Below the upper base wall 804 is a sealable internal void 807. An orifice 808, at position 809 on side wall 802 is used to evacuate the evacuable void 803, which is then sealed by a plug 810.

Referring to Fig. 29 the sealable internal void 807 of fluid containment vessel 800 is being filled by a thermal energy absorbing material 811. Once filled the sealable internal void 807 is sealed by a base unit 812.

Referring to Fig. 30 there is illustrated the fluid containment vessel 800, which is now ready for use. The base unit 812 is a two-part sandwich with the outer part 813 being formed of a rubber material and the inner part 814 being formed of a compressible material, which accommodates any incease in volume of the energy absorbing material 811, when cooled in use.

The words comprises/comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Claims

1. A fluid containment vessel having a base and an interior volume for containing a fluid above the base; wherein the base comprises a sealed internal void, the internal void being separated from the interior volume of the vessel by an upper wall; the vessel further comprising a temperature control structure situated within the internal void, the temperature control structure comprising: a thermal energy absorbing material comprising water; and a compressible member; wherein said temperature control structure substantially fills said internal void; wherein said compressible member is adjacent and a lower wall of said internal void, such that the thermal energy absorbing material is adjacent the upper wall; and wherein said compressible material is sufficiently large in volume and sufficiently compressible to absorb the thermal expansion arising when said thermal energy absorbing material is cooled to below 0°C.

2. A fluid containment vessel as claimed in any preceding claim, wherein said thermal energy absorbing material further comprises a freezing point depressant.

3. A fluid containment vessel as claimed in claim 2, wherein said freezing point depressant comprises ethyl alcohol.

4. A fluid containment vessel as claimed in claim 2 or 3, wherein said freezing point depressant comprises sodium chloride.

5. A fluid containment vessel as claimed in any of claims 2-4, wherein said freezing point depressant is added in an amount effective to depress the freezing point of said thermal energy absorbing material to between -1.5°C and -10°C.

6. A fluid containment vessel as claimed in any preceding claim, wherein said thermal energy absorbing material comprises a thickening agent.

7. A fluid containment vessel as claimed in claim 6, wherein said thickening agent is selected from sodium polyacrylate, food-grade hydrogels, food-grade cellulose ethers, carboxymethyl cellulose (CMC), agar, carrageenans, and natural gums.

8. A fluid containment vessel according to claim 6 or 7, wherein said thickening agent is provided in a volume of between 1 % and 20% of the volume of said thermal energy absorbing material.

9. A fluid containment vessel according to claim 8, wherein said thickening agent comprises sodium polyacrylate and is provided in a volume of between 2% and 8% of the volume of said thermal energy absorbing material.

10. A fluid containment vessel according to claim 9, wherein said thickening agent comprises a natural gum and is provided in a volume of between 4% and 15% of the volume of said thermal energy absorbing material.

11. A fluid containment vessel as claimed in any preceding claim, further comprising a substantially rigid, permeable structure located in the internal void, the thermal energy absorbing material being distributed within and through the permeable structure.

12. A fluid containment vessel as claimed in claim 11 , wherein said substantially rigid, permeable structure is formed of a material having a thermal conductivity of at least 10 Wnr

13. A fluid containment vessel as claimed in claim 11 , wherein said substantially rigid, permeable structure is formed of a metal or of graphite.

14. A fluid containment vessel as claimed in any of claims 11-13, wherein said substantially rigid, permeable structure is an open cell foam.

15. A fluid containment vessel as claimed in claim 14, wherein said open cell foam is a copper foam.

16. A fluid containment vessel according to any preceding claim wherein the upper wall is configured to project into the vessel interior above its base.

17. A fluid containment vessel according to claim 16, wherein the upper wall is defined by a protrusion into the interior volume of the vessel, said protrusion being an inverted bulbous protrusion, a hollow finger shaped protrusion, a bell-shaped protrusion, a domed protrusion or an inverted domed protrusion.

18. A fluid containment vessel according to any preceding claim, wherein the base further comprises a lower wall which together with the upper wall seals the internal void.

19. A fluid containment vessel according to claim 18, wherein the lower wall comprises a disk which is affixed into place within a recess in the base of the vessel.

20. A fluid containment vessel according to any preceding claim, wherein the internal void has a decreasing width from the base towards the upper wall, whereby the compressible member is held in place adjacent the base by the decrease in width.

21. A fluid containment vessel according to claim 20, wherein the upper wall is a generally dome shaped wall extending to the base and defining said decreasing width as it rises towards an apex.

22. A fluid containment vessel according to any preceding claim, the vessel being formed of glass.

23. A fluid containment vessel according to any one of claims 1-21 , the vessel being formed of metal material and having double walls with an evacuable void between the walls.

24. A fluid containment vessel according to claim 23, wherein the metal material is stainless steel.

25. A method of manufacturing a fluid containment vessel, comprising the steps of: a. providing a vessel body having a base, an interior volume for containing a fluid above the base, and an open internal void below the base, the internal void being separated from the interior volume of the vessel by an upper wall; b. inserting a thermal energy absorbing material comprising water into the internal void in contact with the upper wall; c. placing a compressible member in the internal void outside the thermal energy absorbing material; d. sealing the internal void with a lower wall, such that said compressible member and said thermal energy absorbing material are sealed within and together substantially fill said internal void; wherein said compressible material is sufficiently large in volume and sufficiently compressible to absorb the thermal expansion arising when said thermal energy absorbing material is cooled to below 0°C.

26. A method of manufacturing a fluid containment vessel according to claim 25, further comprising the step of inverting the vessel to expose the internal void uppermost prior to step (b).

27. A method according to claim 25, wherein said thermal energy absorbing material further comprises a thickening agent to increase the viscosity thereof and facilitate material handling during steps (b) and (c).

28. A method according to any one of claims 25-27, for manufacturing the vessel of any of claims 1-24.

29. A fluid containment vessel having a base and an interior volume for containing a fluid above the base; wherein the base comprises a sealed internal void, the internal void being separated from the interior volume of the vessel by an upper wall; the vessel further comprising a temperature control structure situated within the internal void, the temperature control structure comprising a thermal energy absorbing material in the form of a gel having gas bubbles dispersed throughout, the gas bubbles collectively providing a compressible volume to accommodate volumetric changes of the gel material during freeze/thaw cycles; wherein the gel is sufficiently viscous and stable throughout freezing and thawing to retain the gas bubbles in position within the volume of the gel.

30. A fluid containment vessel having a base and an interior volume for containing a fluid above the base; wherein the base comprises a sealed internal void, the internal void being separated from the interior volume of the vessel by an upper wall; the vessel further comprising a temperature control structure situated within the internal void, the temperature control structure comprising a thermal energy absorbing material comprising water; wherein the lower surface of the base below the temperature control structure is sealed with a flexible membrane permitting expansion and contraction of the thermal energy absorbing material during freeze/thaw cycles.

31. A fluid containment vessel having a base and an interior volume for containing a fluid above the base; wherein the base comprises a sealed internal void, the internal void being separated from the interior volume of the vessel by an upper wall; the vessel further comprising a temperature control structure situated within the internal void, the temperature control structure comprising a thermal energy absorbing material comprising water; and wherein the lower surface of the base below the temperature control structure is sealed with a surface providing a connection to an expansion chamber flexible membrane permitting expansion and contraction of the thermal energy absorbing material during freeze/thaw cycles.