WO2005108884A1

WO2005108884A1 - Reduced temperature storage container

Info

Publication number: WO2005108884A1
Application number: PCT/GB2005/001692
Authority: WO
Inventors: Robert Anthony Long
Original assignee: Robert Anthony Long
Priority date: 2004-05-06
Filing date: 2005-05-06
Publication date: 2005-11-17
Also published as: GB0622782D0; GB2430482A; GB0410192D0

Abstract

Storage container (30) comprising: an inner surface (32) defining a storage compartment (33); an outer surface (31) defining an external surface of the container; a cavity (34) disposed between the inner and outer surfaces for receiving a refrigerant; and means (40) for filling the cavity with the refrigerant. Also disclosed is an associated method.

Description

Reduced Temperature Storage Container

The present invention relates to a storage container for maintaining the contents of the container at a reduced temperature for a relatively prolonged period of time.

Prior art containers for performing this function tend to comprise an insulated box into which the contents are placed together with one or more packs (known as ice- packs) comprising a frozen liquid, such as one or more of water, ethylene glycol and propylene glycol. Such prior art containers are commonly referred to as coolers or cool-boxes .

Such containers are typically used to transport food for picnics, whereby the food may be prepared in advance and then consumed some time later, having been maintained in a chilled environment for the intervening time. However, the control of the internal temperature of such containers is difficult if not impossible and it can therefore be difficult to maintain a suitably chilled environment.

A problem with such containers is that they require the user to have access to a freezer so that the ice-packs may be pre-frozen before use. Often, when on holiday and staying, for instance, in a hotel, access to a freezer may not be possible. Also, if flying to a holiday destination, it may not be desirable, or even possible, to transport a suitable container to the holiday destination.

An aim of embodiments of the present invention is to overcome, or at least ameliorate, the aforementioned and other problems experienced with prior art coolers. According to an aspect of the present invention, there is provided a storage container comprising: an inner surface defining a storage compartment; an outer surface defining an external surface of the container; a cavity disposed between the inner and outer surfaces for receiving a refrigerant; and means for filling the cavity with the refrigerant.

Preferably, thermal insulating material is provided between the cavity and the outer surface.

Preferably, the thermal insulating material comprises a high density polyurethane foam.

Preferably, the refrigerant is a mixture of water and at least one of a glycol, an alcohol, a salt, an organic and an inorganic compound.

Preferably, the mixture is a mixture of water and alcohol, including at least 60% water.

Preferably, the means for filling the cavity with the refrigerant comprises a valve.

Preferably, the container further comprises a valve for allowing the expulsion of air from the cavity when it is being filled.

Preferably, the container further comprises a lid for sealing the storage compartment. Preferably, a system is provided, further including apparatus for preparing a suitable refrigerant.

Preferably, the apparatus for preparing the refrigerant comprises a scraped-surface heat-exchange refrigeration system.

According to a second aspect of the present invention, there is provided a method of maintaining a storage compartment of a storage container at a relatively reduced temperature, comprising the steps of: providing a storage container according to one or more of the preferred features of the first aspect of the invention; and filling the cavity of the storage container with a refrigerant having a temperature lower than the ambient temperature outside the container.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:

Figure 1 shows a perspective view of a container according to an embodiment of the present invention;

Figure 2 shows a cross-sectional view through a container according to an embodiment of the present invention; and

Figure 3 shows an embodiment of the invention coupled to a recharging station.

Often, when travelling away from home, it is not always possible or convenient to carry a chilled food storage container or ice-box. This may be due to shortage of space in a vehicle or limited luggage allowance if travelling by air. However, it is often desirable to have access to such an item when at one's destination, particularly if visiting a warmer country and it is desired to take a picnic to the beach, for example.

An embodiment of the present invention is shown in Figure 1. The chiller unit 10 comprises two major parts - a lid 20 and a container part 30. The chiller unit is suitably manufactured from lightweight plastics material having good thermal insulation properties. A typical material is high-density polyurethane, which has a U value of approximately 0.02 Watts/m/deg K. The U value is a measure of the rate of heat transmission through a material. Other materials are of course usable and will be well known to the person skilled in this field.

The lid 20 is shaped to sit atop the container 30. It may be provided with a protruding portion to enter the compartment 33. In addition, or alternatively, the lid 20 may be provided with one or more fastening devices to ensure a good thermal seal with the container 30. Such fastening devices may include buckles, straps, sprung clips or any other suitable device. The lid may additionally be provided with a carrying handle.

The container 30 comprises an outer wall 31, which defines an external appearance of the container 30. The interior of the container 30 is defined by an interior wall 32, which further defines a recess 33 for storing food. As can be seen in Figure 2, located between the interior 32 and exterior 31 walls is a cavity 34. The cavity is provided to receive a chilling solution for maintaining an interior temperature of the chiller unit 10 at a depressed level. The chilling solution is introduced into the cavity 34 via valve 40 which allows external access to the cavity.

Figure 2 shows that the outer wall 31 is relatively thicker than the inner wall 32. This is as the outer wall provides thermal insulation against the external ambient conditions and, as such, helps to maintain the effectiveness of the chilling solution over a longer period. The interior wall 32 is thinner as this allows the chilling solution to have a more direct effect on any food stored in the recess 33. However, the dimensions of the walls are selected so as to offer a compromise between thermal insulation and ease of transportation. If the walls were configured to optimise their thermal properties, this would adversely affect the weight and transportability of the unit 10. Conversely, if the weight were optimised, the thermal characteristics of the unit 10 would be adversely affected.

However, in alternative embodiments, where ease of transport is not such an important issue, the dimensions of the walls may be selected such that thermal insulation is given a greater priority than weight. Such alternative embodiments will b described in greater detail later.

The interior wall 32 and casing forming the exterior of the container may comprise any suitable plastics material. Suitable plastics materials may preferably be formed into shape using injection, rotary or vacuum forming methods. The finished result using such materials is hygienic, durable and aesthetically pleasing.

When the chilling solution is introduced into the cavity 34, the interior recess 33 of the container 30 is surrounded on at least 4 sides, and possibly the base also, by a substance at a temperature lower than the ambient temperature of the surrounding environment. This serves to maintain the interior of the container 30, and thus its contents, at a lower temperature than would otherwise be the case.

Over time, in normal use, the temperature of the chilling solution will rise, but it is anticipated that the useful operating time of a container according to an embodiment of the invention will be several hours in typical operating conditions. Such a period will generally allow food and drink to be chilled for a suitable length of time.

The exact composition of the chilling solution, or thermal paste, which is introduced into cavity 34 can vary depending on the specific requirements in any particular case. Typical compositions of the solution include mixtures of water and one or more of glycols, ethanol, methanol, various salts or other suitable organic or inorganic compounds. Preferred compositions include a mixture of water (95% by volume) and either methyl or ethyl alcohol (5% by volume) . These have the added advantage that their specific gravity helps with the mixing process by reducing the buoyancy of the ice crystals in the finished mixture. The effect of the substance which is mixed with the water is to depress the freezing point of the solution.

Other compositions of the chilling solution are possible. Other preferred compositions comprise a mixture of water and ethylene glycol in the ratio 60:40, although this can vary up to a of ratio 95:5. The exact composition is not essential to the operation of embodiments of the invention.

The chilling solution operates on a phase-change basis. This means that the solution is effectively liquid and when first introduced to the cavity 34, contains a certain proportion of ice crystals. As the solution is exposed to heat, some of the ice crystals melt and revert to water, but as the heat required to do this corresponds to the latent heat associated with this phase change, the net temperature change in the solution is zero. Effectively, the temperature of the solution only begins to rise once all ice crystals have melted.

The chilling solution may be prepared by any of a variety of different processes. A preferred way of producing a suitable solution uses what is known as a ^Λscraped- surface' heat exchanger. This apparatus includes a vessel containing the chilling solution. The vessel is chilled via a suitable heat exchange, or other refrigeration, process so that the solution in the vessel approaches its freezing point. The solution is simultaneously agitated by a rotor which acts to scrape away any solution which freezes and solidifies on the interior wall of the vessel. The ice crystals thus produced are spiky' as they are scraped from the cold surface but, as the crystals are stirred in the vessel, they become more spherical and smoother over time. The individual crystals are prevented from fusing together by the host fluid which has a lower freezing point.

Embodiments of the present invention allow suitable food storage containers to be made available to users in a variety of situations. In one embodiment, the containers may be rented to a user on a short-term basis. Before the user takes possession of the container, its internal cavity is charged with the chilled solution which then acts to maintain the storage compartment of the storage container at a reduced temperature for a prolonged period of time.

In a preferred embodiment, a retail outlet, or other merchant, such as a hotel, acquires a stock of a number of storage containers, possibly of different capacities, and rents them to customers/guests. The stock of containers can be stored with the internal cavity empty. When a user wishes to rent one of the containers, the internal cavity can be charged with a chilling solution which will maintain the storage compartment of the container at a relatively reduced temperature.

The chilling solution is maintained at a reduced temperature in a freezing apparatus as previously described, and can be periodically topped up as required. When a customer rents a container, its internal cavity 34 is filled with the chilled mixture. The filling operation involves coupling a valve 40, allowing access to cavity 34, to a suitable hose for delivering the mixture from its storage vat. In addition to the filling valve, the container 30 includes a second valve 42, which functions as a vent, allowing the air in the cavity to be expelled as the chilling solution is introduced. The second valve is a one-way valve and also acts as an overflow valve.

Once the cavity 34 is filled, removal of the hose causes the valve 40 to seal the cavity automatically, retaining the chilled mixture within the storage container 30.

When the storage container is returned to the retail outlet at the end of the hire period, the by-now, melted chilling solution is returned to the vessel 100 for re- freezing and re-use. The solution can be pumped from the cavity 34 directly into the vessel 100. The storage container 10 can then be stored in a discharged condition, ready for re-use at a later time.

Other uses aside from the storage of food can be envisaged for embodiment of the invention. For instance, the transportation of human organs for transplant requires the organs to be maintained at a reduced temperature until ready to be transplanted. Embodiments of the present invention, suitably charged with a chilling solution offer a convenient and hygienic way of performing this task, Indeed, through careful selection of the chilling solution, an accurate temperature may be maintained for an extended period inside the container.

Further uses of the underlying technology result in a range of alternative embodiments. Particular examples utilise flexible materials in construction of a suitable container. In this way, a portable chiller bag construction is possible, which otherwise has a similar construction to the embodiments described thus far.

Such a construction allows smaller and more portable cooler devices to be manufactured and have the added advantage of being less heavy. The basic ^sandwich' constructions remains, with inner and outer skins defining a cavity into which the chilling solution is introduced.

A further alternative embodiment uses the underlying technology in the construction of cold storage structures, which can range in size from a small chest, as described previously, to small buildings. The technology used is easily scalable, and so there is no practical limit to the size of storage facility that can be assembled.

Uses of embodiments offering bulk cold-storage of materials could include emergency situations where large stores of food need to be maintained in a chilled environment. Also, in the case of natural disaster, temporary morgue facilities can be quickly and easily erected which would not need to have powered refrigeration facilities on site. The apparatus for preparing the chilling solution can be powered from a diesel generator, and provides an efficient way of providing a chilled environment without permanently occupying a power generation source. The chilling liquid can simply be refreshed at periodic intervals as required.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference .

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A storage container comprising:

an inner surface defining a storage compartment;

an outer surface defining an external surface of the container;

a cavity disposed between the inner and outer surfaces for receiving a refrigerant; and

means for filling the cavity with the refrigerant.

2. A storage container as claimed in claim 1 wherein thermal insulating material is provided between the cavity and the outer surface.

3. A storage container as claimed in claim 2 wherein the thermal insulating material comprises a high density polyurethane foam.

4. A storage container as claimed in any preceding claim further including the refrigerant.

5. A storage container as claimed in claim 4 wherein the refrigerant is a mixture of water and at least one of a glycol, an alcohol, a salt, an organic and an inorganic compound.

6. A storage container as claimed in claim 5 wherein the refrigerant is a mixture of water and alcohol, including at least 60% water.

7. A storage container as claimed in any preceding claim wherein the means for filling the cavity with the refrigerant comprises a valve.

8. A storage container as claimed in any preceding claim wherein the container further comprises a valve for allowing the expulsion of air from the cavity when it is being filled.

9. A storage container as claimed in any preceding claim further comprising a lid for sealing the storage compartment .

10. A system comprising:

a storage container as claimed in any preceding claim; and

apparatus for preparing the refrigerant.

11. A system as claimed in claim 10 wherein the apparatus for preparing the refrigerant comprises a scraped-surface heat-exchange refrigeration system.

12. A method of maintaining a storage compartment of a storage container at a relatively reduced temperature, comprising the steps of:

providing a storage container as claimed in any one of claims 1 to 9; and filling the cavity of the storage container with a refrigerant having a temperature lower than the ambient temperature outside the container.