FIELD OF THE INVENTION

The present invention relates to an air conditioning unit that uses ambient air passed over ice created using a refrigeration cycle to cool the ambient air.

BACKGROUND OF THE INVENTION AND PRIOR ART

Air conditioning is widely used in hot countries and countries with hot summers, and its use ensures that a modern standard of living is achievable in areas that would otherwise be inhospitable or difficult for people to settle in. Modern air conditioning units are inefficient and require large amounts of input energy in order to cool a space or a certain volume of air.

Accordingly a number of patent applications have been filed in an attempt to resolve this or similar problems, including the following:

US 2008/0104971 A1 describes and shows a thermal storage and transfer system that includes a cooling system and which provides a method of producing a cool airstream using ice or other frozen material. The ice is disposed in a container with the condensers and evaporators off the heat pipes respectively inside and outside the container. A fan blows air across the evaporator sections through a duet to circulate the air within an enclosed airspace to be cooled. A separate refrigeration system which may be used to independently cool the airspace also freezes water or another liquid to produce ice or other frozen material in the container. The cooling system may be applied for example to motor vehicles, for providing cooling for several hours after the vehicle engine has been switched off.

WO 2006/135177 A1 describes and shows a cold air and hot air discharging refrigerator, and an operating method and apparatus thereof. The refrigerator includes a cold air generating device adapted to cool air by use of cold air within a freezing chamber so as to discharge the cooled air, or a hot air generating device adapted to heat air by use of waste heat of the refrigerator or electric heater so as to discharge the heated air. The refrigerator functions as a cold air generator or hot air generator, and thus eliminates the necessity for installing a separate cold air generator or hot air generator in a narrow kitchen.

WO 2006/110022 A1 describes and shows a cooler that uses ice to provide environmental cooling, wherein the outer surface of an air pipe is directly exposed to ice or iced water stored in the cooler. The pipe extends over the entire length of the cooler between an inlet in one of the side walls and an outlet in the opposite wall, and is secured to the walls to prevent water or air ingress or egress between the pipe and the ice in the cooler. An electric fan provided in the pipe inlet causes warm air to flow into the pipe, where it is cooled as it moves towards the pipe outlet.

The above, and other conventional, air conditioning systems all have limited efficacy in providing optimum air cooling, especially from a system which is overall energy efficient. In contrast, the present invention seeks to improve upon known air conditioning systems, and to provide an air conditioning system which not only is more overall energy efficient, but also provides excellent cooling of ambient atmospheric air through a novel use of a refrigeration cycle.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a refrigerating air conditioning unit, comprising: a chamber configured to hold a volume of ice; a refrigeration means configured to freeze water within the chamber; a chamber passage configured to allow atmospheric air to pass therethrough, the passage and chamber being at least partly contiguous; and an air circulating means configured to either drive and/or draw air into and/or from the atmosphere through the chamber passage; wherein the refrigerating air conditioning unit is configured such that the volume of the chamber is variable, e.g. in order to alter the volume of ice formable in the chamber.

In another aspect of the invention, there is provided a method of cooling ambient atmospheric air, comprising: providing a refrigerating air conditioning unit according to the preceding aspect of the invention or any embodiment thereof; and then for cooling the air conducting the steps of: operating the unit so as to form a volume of ice in the chamber; circulating the air through the chamber passage so as to come into contact with the ice in the chamber and be cooled thereby; and returning the cooled air to the atmosphere.

Using ice to cool the air allows the ice to be created using a known refrigeration cycle, which overall is more energy-efficient than using a conventional air conditioning unit to cool the air directly immediately before it is required. Furthermore, having a chamber for housing a supply of ice so formed and whose volume can be altered, allows not only a required supply of ice to be established but in some embodiments may also allow a user to choose how much ice they require for any particular use of the unit or degree of cooling that may be desired.

Accordingly, in some embodiments the chamber may be constructed and arranged such that its volume is variable during the formation therein of the ice. In some such embodiments the volume of the chamber may vary in accordance with the volume of ice to be formed, or being formed, therein. In some example embodiments the variable volume of the chamber may be controlled manually by a user, e.g. from outside the unit, whereas in other example embodiments the variable volume of the chamber may be controlled automatically by the unit itself, e.g. by control means provided therein or by the inherent construction of the chamber, in dependence on the volume of ice to be formed, or being formed, therein.

In an embodiment, the refrigeration means may be a vapour-compression refrigeration system or device, configured to add ice incrementally to the chamber as the ice is formed. This refrigeration system or device may be based on, and comprise, the known general components of any suitable such known refrigeration system or device, such as that used in principle in a conventional domestic or industrial freezer or deep-freeze. This type of refrigeration system is a well-known, reliable and economical apparatus suitable for freezing water in an energy-efficient manner.

In some embodiments the refrigeration means may be configured for connection to a mains electrical power source. This allows the refrigeration means, and thus the unit, to be conveniently operated in a variety of domestic or industrial locations.

In many practical embodiments the unit may, if desired or if necessary, further comprise thermal venting or evacuation means for removal, if or as or to any extent necessary, of heat, e.g. in the form of warmed air, from the refrigeration means or the vicinity thereof to a remote location as it removes heat from the water in forming the ice. Such a remote location may for example be a space, region or environment external of a room or space within a building in which the unit is to be operated for cooling the ambient air therein. Thus, such thermal venting or evacuation means may serve to remove, if or as or to any extent necessary, excess heat from the system embodied by the unit, including the atmospheric air in the room or space to be cooled, rather than simply feeding it back into the atmosphere where it would release its heat energy again and thereby at least partially annul the advantageous cooling effects of running the unit. Suitable thermal venting or evacuation means may comprise for example any suitable length and/or configuration of hose, pipe or other conduit, optionally in combination with an e.g. low-power pump or extractor, examples of which are widely available in the art. In some embodiments, the chamber may have or be bounded by a vertically movable base, the volume of the chamber being changeable by altering the vertical position of the base relative to the refrigeration means. This allows the volume of the chamber to be altered, and altering the position of the base provides a simple way to achieve this without having to also move equipment at the top of the unit. In some such embodiments the base may be moveable into a given vertical position naturally (especially without user-intervention) through the gravitational weight of the ice formed, or being formed, in the chamber.

In some embodiments the base may comprise a peripheral, especially an upstanding, wall, flange or lip configured for retaining an amount of water in or on the base during the initial stages of forming the ice in the chamber. The peripheral wall, flange or lip thus serves to maintain a minimum volume of water in or on the base during the initial stage(s) of the freezing process. This enables an initial volume of ice to be formed within the refrigeration means, and once that stage has been reached the thus-formed initial volume of ice may be self-stabilising on the base. Thereafter, as more and more water is frozen and added to the upper end or region of the current volume of ice within the chamber, so the body of ice may tend to move downwardly under its gravitational weight while being retained on the base by its peripheral wall, flange or lip, thereby moving the base downwardly with it, optionally against a biasing force provided by biasing means which may optionally be provided in the unit to mount the base relative to the unit housing.

Thus, in another embodiment, the refrigerating air conditioning unit may further comprise a housing, the base (in embodiments where such is present) being movably mounted relative to the housing, optionally via one or more biasing means, e.g. one or more springs. This provides a simple and effective mechanism for altering the volume of the chamber by movement of the base relative to the housing, optionally in cooperation with (or against the biasing force of) the biasing means.

In some such embodiments the base may optionally be perforated or may have any suitable number and/or arrangement of holes or apertures therein, especially in a bottom and/or one or more sides thereof. In particular this may assist in the gravitational withdrawal out through the base and into the bottom of the unit meltwater from the volume of ice resulting from the melting thereof as it cools the air passing through the unit.

In embodiments of the invention the chamber may be open-sided or substantially or predominantly open-sided, or alternatively it may have or be defined by one or more sides or walls which are at least partially closed or occluded to enhance the containment of the ice formed in the chamber. In some example forms the chamber may be generally substantially circular or elliptical in cross-section, or alternatively it may be generally substantially rectangular in cross-section.

In some embodiment forms, any one or more sides or walls of the chamber may be constructed and arranged to allow or enhance the variable nature of the chamber's interior volume. For example, one or more walls or wall portions of the chamber may be moveable relative to a or a respective adjacent other wall(s) or wall portion(s). Such relative movement may be achieved for example through use of a telescopic, concertina or other like arrangement. Optionally one or more seals may be included between any such adjacent yet relatively moveable walls or wall portions, to guard against possible water leakage.

In an embodiment, the chamber passage may pass, or may extend, internally of the chamber. In one such embodiment the chamber passage may pass or may extend substantially through the centre of the chamber, e.g. so as to be substantially or approximately co-axial or co-centric therewith. This provides an efficient position for maximising exposure of atmospheric air to the cooler ice formed and present in the chamber.

In an embodiment, the chamber passage may be aligned substantially vertically, in particular so that in some embodiments this alignment may match the general alignment of the volume or block of ice as it is formed in the chamber. This allows temperature differentials and convection to be more effectively harnessed.

In some embodiments the chamber passage may be of a cross-sectional shape which substantially corresponds or matches (although scaled in comparison with) or is geometrically similar to the cross-sectional shape of the chamber. Thus, in some example forms the chamber passage may likewise be generally substantially circular or elliptical in cross-section, or alternatively it may be generally substantially rectangular in cross-section.

In an embodiment, the unit may further comprise a height adjustment plate vertically movable within the unit, especially moveable relative to the base, so as to selectively contact or abut the base and in so doing hold the base at a desired height within the unit (especially relative to the refrigeration means) as defined by the selected height of the height adjustment plate. This provides an effective way to additionally control the volume of the chamber and thus the volume of ice formed, in particular by controlling the maximum height (and thus maximum volume) of the chamber, e.g. as may be desired or necessary at any given time or point in the refrigeration cycle or stage of use of the unit.

In an embodiment, the refrigerating air conditioning unit may further comprise a crank connected to the height adjustment plate and manipulatable by a user in order to alter or adjust the height of the height adjustment plate and thus the associated limiting position of the base when abutted by the height adjustment plate. This is a simple and effective mechanism for adjusting the height of the height adjustment plate. Alternatively, the height of the height adjustment plate may be selected, adjusted or controlled automatically, e.g. electronically, substantially without, or without ongoing, user-intervention, for example by inclusion in the unit of control means, e.g. electronic control means, which may be set or programmed to govern or control the height of the height adjustment plate in an optimum manner, depending on the circumstances of use of the unit and the overall parameters of the cooling operation.

In an embodiment, the housing may be configured such that an outer passage is formed between the housing and the chamber, and so that atmospheric air entering the chamber must pass through both the outer passage and the chamber passage (or vice versa) before exiting to the atmosphere again having been cooled. This maximises exposure of the air to the ice in the chamber.

In an embodiment of the invention, the air circulating means may be a fan, e.g. an electric fan. This is a well-known, simple and effective mechanism for effecting air circulation. In some such embodiments, if desired or necessary the fan may be controlled electronically so as to drive or draw air into or from the atmosphere through the chamber passage at a predetermined flow rate or speed. Furthermore the fan may be controllable to actuate the fan only when cooling of the ambient air is required, which may be dictated for example by a thermostat or other temperature-sensitive device which detects when a temperature of the ambient air exceeds a preset threshold value. Such a threshold value may of course be altered or adjusted by a user. Any such degree of control of the fan may be accomplished by control means which may additionally be provided in the unit, optionally as part or a component of an overall control system which also controls other parameters of the unit's operating system.

In some embodiments the unit may further comprise a water reservoir, which in some such embodiments may be located in an upper region of the unit, especially in the vicinity of or adjacent to and/or in fluid communication with (e.g. via a tube, hose or other conduit) an upper region or portion of the chamber. If desired, the water reservoir may be provided with a water inlet means, e.g. one or more inlet apertures, tubes, hoses or other conduits, connectable to a source of water external to the chamber, especially external to the unit, such as a mains water supply or a (preferably cold) water supply forming part of a building's central heating system. This enables the water reservoir to be initially filled and/or replenished as or when necessary during use of the unit.

In an embodiment of the invention, the refrigerating air conditioning unit may further comprise a recirculating means configured to receive meltwater from the ice, especially meltwater released therefrom below the chamber, and to re-circulate the meltwater to the top of the chamber - or even the water reservoir mentioned above - ready for re-freezing. This helps to maintain the overall volume of ice as e.g. lower extremities or portions thereof melt as air is cooled by the ice, so that optimum efficiency of air cooling is maintained.

In an embodiment, the recirculating means may comprise one or more pipes and a pump. These are well-known, simple and effective pieces of apparatus for water circulation.

In some embodiments of the invention, in particular in embodiments where incoming ambient air first enters the unit external to the chamber and subsequently enters and passes through the chamber passage (where it is cooled by the ice in the chamber) before exiting the unit, the unit may additionally comprise air bypass means disposed around or adjacent the refrigeration means and configured to pass incoming air externally past the refrigeration means substantially without coming into contact therewith. In some such embodiments the air bypass means may suitably comprise a plurality of tubes or other conduits, e.g. formed of a thermally insulating material (e.g. a plastics material) mounted in an array around (especially not touching) the external boundaries or periphery of the refrigeration means and extending at least over the height thereof. In some example embodiments the air bypass tubes may extend over a height sufficient also to bypass an upper portion of the chamber, which upper chamber portion is likewise also likely to be particularly cold during use of the unit. In this manner the incoming ambient air can bypass the refrigeration means (and optionally also the upper portion of the chamber) and pass into the cooling chamber passage substantially without coming into thermal contact with the exterior of the refrigeration means, thereby avoiding undue condensation and consequential build-up of frost or ice on the exterior of the refrigeration means during use of the unit.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples and alternatives, and in particular the individual features thereof, set out in the preceding paragraphs, in the claims and/or in the following description and drawings, may be taken independently or in any combination. For example features described in connection with one particular embodiment are applicable to all embodiments, unless expressly stated otherwise or such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of refrigerating air conditioning unit according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

FIGURE 1 is a perspective view from one side and above of an embodiment of the refrigerating air conditioning unit of the present invention;

FIGURE 2 is a perspective view of the refrigerating air conditioning unit of FIG. 1 , shown with the outer housing/casing removed and also with the air circulating fan, water reservoir and thermal venting/evacuation pipe also omitted for clarity;

FIGURES 3(a) and 3(b) are schematic cross-sectional views of the refrigerating air conditioning unit of FIG. 2 in different stages of use, the volume of the ice chamber in FIG. 3(b) being greater than that in FIG. 3(a); and

FIGURE 4 is a schematic perspective diagram of part of an upper portion of an alternative embodiment of the invention, showing an arrangement of air bypass tubes which surround the refrigeration device and upper portion of the chamber and shield the incoming ambient air from the refrigeration device as it passes into the lower region(s) of the unit ready for cooling via flow through the chamber passage.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring firstly to FIGS. 1 , 2 and 3(a) and 3(b), the refrigerating air conditioning unit 1 has main parts as follows: a refrigeration device 2 for freezing water and located in an upper region of the unit 1 , a chamber 3 that holds ice created by the refrigeration device 2, and a chamber passage 4, the chamber passage 4 being formed internally of and through the chamber 3 so that the walls of the chamber passage 4 are formed at least partially within the chamber 3 (optionally being at least partially in common with the walls of the chamber 3) - so that the walls of the chamber passage 4 and the interior of the chamber 3 are at least partially contiguous. In practice the formation of this contiguous chamber passage 4 may be achieved by appropriate corresponding configuration of the refrigeration device 2, such that it forms a volume of ice which is itself configured to form internally thereof the desired internal chamber passage 4 actually within the block of ice thus formed. Thus, the walls of, and/or which define, the chamber passage 4 are at least partially in common or contiguous with the chamber 3 or even the ice itself contained therein, whereby air passing through the chamber passage 4 is in thermal contact with the ice present in the chamber 3 and thereby able to be cooled thereby as it flows through the chamber passage 4.

The bottom of the chamber 3 is defined by, or bounded by a base 7, which may be perforated or contain any number of apertures in its bottom wall to allow meltwater to drain therethrough (see further below). The base may advantageously be bounded on its sides by a peripheral upstanding wall, flange or lip (not shown), to assist containment of the ice on the base and - especially - for retaining thereon an initial volume of water during the initial stages of formation of ice in the chamber 3, at which stage the base 7 may typically be at its uppermost position immediately below the refrigerating device 2.

The chamber 3 is shown here (see FIGS. 3(a) and (b)) as being substantially open-sided, it being formed generally as a space within the unit 1 and bounded at its upper region by the refrigeration device 2 and at its lower region by the moveable base 7. However, if desired or necessary the chamber 3 may comprise on or more lateral sides or side portions which encase or define it and to separate the chamber 3 from the remainder of the unit's interior.

An electrically powered fan 5 is located at one, e.g. an upper, end of the chamber passage 4 to either drive or draw air through the chamber passage 4, i.e. from the atmosphere, over or through the ice volume contained in the chamber 3, and out to the atmosphere again. Using ice to cool the air allows the ice to be created using a refrigeration cycle, which overall is more energy-efficient than using a conventional air conditioning unit to cool the air directly immediately before it is required. Moreover, having a chamber where the volume can be altered to accommodate a variable and/or selectively controllable volume of ice allows a user to preset and/or choose and/or optimise how much ice is formed and thus how much cooling is effected during any particular use, or period of use, of the unit. For example, the chamber 3 could be filled with ice overnight or when power draw is low and when it tends to be cooler, and the refrigerating air conditioning unit 1 can then be ready for use in the morning.

Located in the top section of the unit 1 is also a water reservoir W (shown schematically here for simplicity, although its precise construction and configuration may be chosen to suit any particular example embodiment of unit). The water reservoir W contains a supply of water for feeding into the top of the chamber 3, e.g. by a tube or conduit (not shown) ready for freezing therein by the refrigeration device 2. The water reservoir W may be filled initially in particular, ready for an initial use of the unit, when an initial volume of ice is needing to be formed. The water reservoir W may also serve to "top up" the chamber with water for ice formation as or when that is needed during use of the unit, e.g. as water may be lost from the system through evaporation. The water reservoir W may be filled via a water inlet nozzle or pipe which is connectable e.g. to a mains water supply as or when needed. If desired the water reservoir W may be fitted with an overflow pipe leading down into the base of the unit, in particular into the drip-tray 16 (see below) in case of any over-filling.

In some example forms, particularly those in which the water reservoir W may tend to form ice crystals therein (especially owing to its proximity to the refrigeration device 2) the water reservoir W may if desired contain an electrically driven screw or churning device for breaking up and/or keeping moving the water and/or water-ice contained in the reservoir W. In this manner the build-up of large amounts of ice crystals or ice within the reservoir W may be avoided.

In the illustrated embodiment, the refrigeration device 2 is a vapour-compression refrigeration system. The various components and elements of pipework etc of the refrigeration system may each independently be positioned or located in any suitable place(s) within the overall unit which best suit it/them from technical considerations, and/or for optimum use of space which may be available. This refrigeration system is in fundamental terms substantially the same as that used in a domestic freezer or refrigerator-freezer, and is a well-known, reliable, economical apparatus suitable for freezing water. The refrigeration device 2 is however constructed and configured for use in this embodiment of this invention such that it forms a volume of ice in the chamber 3 of any particular desired cross-sectional shape. The cross- sectional shape of the chamber 3 itself may be configured for this purpose, and/or optionally the refrigeration device may also be configured to add ice to the forming volume also in that desired cross-sectional shape. For example, in one example form the volume of ice may be formed as a hollow body, especially in the form of a hollow cylinder or hollow cone, e.g. with a channel or void passing centrally through the interior thereof for defining the internal chamber passage 4 through which the air to be cooled passes during use of the unit. Other three dimensional shapes of the ice volume may of course be possible.

The refrigeration device 2 adds ice incrementally, or possibly even continuously, to the chamber 3 as the ice is formed until the chamber 3 is filled. This incremental adding of the ice to the chamber 3 may be in discrete freezing stages, or alternatively may be in a substantially continuous operation but in which ice is added to an already forming integral block in small or tiny increments, i.e. as more and more water is frozen it is inherently and directly added to the growing block of ice in the chamber 3. During this operation the refrigerating device 2 may be operated either substantially continuously or alternatively it may be operated intermittently or in stages, e.g. to allow the forming ice block to lower itself a short distance (e.g. by a small amount of melting at its edges or sides where it is gripped by the refrigerating device 2 or the upper part of the chamber 3), before more ice is added to it. As desired or as necessary, therefore, as the ice block forms and grows, so it extends increasingly downwards into the space within the chamber 3, as depicted in the different stages of operation shown in FIGS. 3(a) and (b). The refrigeration device 2 is connected to and powered by a mains electrical power source. This allows the refrigeration device 2, and thus the unit 1 , to be conveniently used in a variety of domestic and/or industrial locations.

The chamber passage 4 and chamber 3 are arranged so that the passage 4 passes vertically upwards through the chamber 3, preferably in the centre of the chamber 3. The fan 5 is located at or adjacent the top of the passage 4 and can either blow air down through the passage or be reversed to suck air upwards through the passage 4. The air can thus flow in either direction for passing it over the ice in the chamber 3 so as to be cooled thereby. In some embodiments, a suction action of the fan 5, to draw air up through the internal chamber passage 4 having already entered the unit 1 from the atmosphere (e.g. via one or more dedicated vents) and passed through the outer passage 11 formed between the housing 6 and the chamber 3, may be particularly effective.

The chamber 3 and refrigerating device 2 are enclosed by a housing or casing 6, e.g. of metal or plastics material. The refrigerating air conditioning unit 1 is configured so that the volume of the chamber 3 can be varied during use of the unit 1 , so that the volume of ice it will hold can likewise be changed, altered or adjusted to suit any particular operational conditions or demands of the unit.

This is achieved by having the base 7 of the chamber 3 moveable vertically upwards and downwards, the base 7 being optionally supported by one or more springs 8, e.g. a pair (or any suitable number) of coil springs at the sides of the unit, that extend from the top of the housing 6 to support the base 7 and which stretch as the ice builds up in the chamber 3 and its weight increases. Therefore, as the ice builds up upon being formed by the refrigeration device 2, it becomes a block which lowers itself, e.g. under its own gravitational weight, downwards within the chamber 3. As it so moves or extends, so the block of ice is added to from the top and as the refrigeration device 2 freezes more water and adds it to the block.

A height adjustment plate 9 is mounted within and connected to the housing 6 below the chamber 3 and is vertically movable within and relative to the housing 6, and in particular relative to the chamber 3. The height adjustment plate 9 plate abuts and supports the base 7 from underneath, and holds it at substantially the same height as the height adjustment plate 9, wherever that is set. If desired or necessary the height adjustment plate 9 may itself be mounted via on one or more coil springs 8a. The height of the height adjustment plate 9 thus dictates the maximum height (i.e. vertical thickness) of the ice block formed in the chamber 3. This provides an effective way to control the vertical position of the base 7 and therefore the volume of the chamber 3 and the amount of ice contained within the unit 1.

The vertical position of the height adjustment plate 9 may be altered manually via one or a pair of cranks 10 (only one being shown in FIG. 2) connected to the height adjustment plate 9 and which can be rotated by a user to alter or preset the height of the height adjustment plate 9. Alternatively the height of the height adjustment plate 9 may be controlled and varied automatically to any necessary or desirable extent by an electrically powered motor under the control of a control device (not shown). This may enable the operation of the unit, and in particular the volume of ice formed in the chamber 3, to be tailored to any particular usage parameters of, or desired of, the unit 1.

It may be preferred that the housing 6 is formed such that an outer passage 11 is formed between the housing 6 and the chamber 3, and so that atmospheric air entering the chamber 3 must pass through both the chamber passage 4 and the outer passage 1 1 before exiting to the atmosphere. This maximises exposure of air to the ice in the chamber 3.

In use, the ice formed as a block in the chamber 3 will melt as heat is transferred from the incoming ambient atmospheric air to the ice, thereby cooling the air by causing the ice to melt. The water from the melted ice drains, e.g. as droplets D, through the perforated or apertured bottom of the base 7 and is collected in a drip tray 16 at the bottom of the housing 6, where it flows into one or more pipes 12 and is pumped back, e.g. by pump 13, or recirculated to the top of the unit 1 (optionally into the water reservoir W or else directly back into the top of the chamber 3) to be re-frozen and added back to the chamber 3 to replenish the ice therein.

Illustrated schematically in FIG.2 is the provision of an optional, though in many cases desirable (or possibly even essential in certain example embodiments), thermal venting or evacuation pipe, hose or other conduit H, for the purpose of removing heat from the system in the form of warmed air from the compressor or other component(s) of the refrigerating system. This outlet pipe, hose or other conduit H may exit to any suitable remote location external to the unit 1 and the room or other environment in which it is intended to operate, in order to remove any excess heat therefrom rather than simply feeding it back into the room or other environment (which might at least partially annul the advantageous cooling effects of running the unit therein).

FIG. 4 shows schematically an example arrangement of an upper portion 30 of an alternative embodiment of unit within the scope of the invention, in which an array of air bypass tubes 20, e.g. of insulating plastics material, surround the upper portion of the chamber 3 and internal chamber passage 4 therein and shield the incoming ambient air from the refrigeration device 2 as it passes into the lower region(s) of the unit 1 ready for cooling via passage through the interior chamber passage 4. The tubes 20 extend at least over the height of the refrigerating device 2, preferably somewhat more than that so that the tubes 20 extend over a height sufficient also to bypass an upper portion of the chamber 3 itself, which upper chamber portion is likewise also likely to be particularly cold during use of the unit. In this manner the incoming ambient air can bypass the refrigeration means 2 (and optionally also the upper portion of the chamber 3 and thus the upper portion of the volume of ice therein) and pass into the lower reaches of the unit 1 and up into the cooling chamber passage 4 substantially without coming into thermal contact with the exterior of the refrigerating device 2, thereby avoiding undue condensation and consequential build-up of frost or ice on the exterior of the refrigerating device during use of the unit 1.

The invention has been described by way of examples only and it will be appreciated that variations may be made to the above-mentioned embodiments without departing from the scope of invention. Furthermore, it will be understood that any features described in relation to any one particular embodiment may be featured in combination(s) with any other feature of any other embodiment, in any combination. Thus, features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. In addition, throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

With respect to the specification therefore, it is to be realised that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. Therefore, the foregoing is considered as illustrative only of the principles of the invention, with variation and implementation obvious and clear on the basis of either common general knowledge or of expert knowledge in the field concerned.

Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as set out in the accompanying claims.