AN INSULATING TRANSPORT AND STORAGE CONTAINER

Abstract

A transport container formed of insulated board such as corrugated or laminated plastics and treated paper and treated card that can provide a high degree of thermal insulation. A pallet shipper storage container that can operate at ultra-low temperatures akin to those at which solids such as carbon dioxide sublimate and method of use of such shippers and containers.

Claims

1. A thermally insulating transport container comprising: a cuboid body comprising six insulating panels; and a coolant support member; wherein the coolant comprises a solid that sublimates; wherein the cuboid panels comprise a base panel, first and second end-wall panels and first and second sidewall panels and a cover panel; wherein the insulation panels are fastened such that they provide a substantially gas-tight seal along mutually orthogonal edges; wherein the coolant support member comprises at least a support tray spaced, in use, from an inside face of the cover panel, the support tray being provided with upstanding support members; wherein a payload volume is defined below the coolant support tray, which payload volume provides sufficient space for a palletized good; wherein, in use, once assembled and provided with coolant, the coolant gases emanating from the coolant are operable to cool the payload volume by sublimation; and wherein a gas valve is provided to enable gaseous pressure control within the cuboid volume due to the sublimation gases arising from the coolant.

2. The container according to claim 1, wherein the insulating panels are formed from multilayer insulating boards selected from one or more of vacuum insulation panels (VIPS), polyurethane foam, plastics foam, cardboard, paper-board, corrugate board, metalized board and glass fibre.

3. The container according to claim 1, the container is provided with a pallet-style base.

4. The container according to claim 3, wherein the pallet style base is affixed to the base panel.

5. The container according to claim 4, wherein the panels are retained together in place by compression restraints.

6. The container according to claim 5, the compression restraints comprise webbing provided with ratchet straps.

7. The container according to claim 1, wherein adjacent panels are provided with resilient tapes along at least one mating face thereof to ensure gas-tight resilience between the panels.

8. The container according to claim 1, wherein the upper lid is removable in use, to permit replenishment of coolant upon sublimation of an initial or subsequent amount of coolant; and provided with coolant, the coolant gases emanating from the coolant are operable to cool the payload volume by sublimation; and wherein a gas valve is provided to enable gaseous pressure within the cuboid volume due to the sublimation gases arising from the coolant.

9. The container according to claim 1, wherein the gas valve is defined by means of a slit provided within the seal to control pressure within the cuboid volume.

10. The container according to claim 9, wherein the gas valve is compressed by a weight of a panel or by compression forces acting by means of a strapping arrangement whereby to control pressure within the cuboid volume.

11. The container according to claim 1, wherein the coolant support member is one of a metallic structure or a plastics structure.

12. The container according to claim 11, wherein the coolant support member is a metallic structure formed from sheet of one of an aluminium alloy or a stainless steel, conveniently apertured whereby to provide a high degree of thermal conduction with a reduced thermal capacity.

13. The container according to claim 1, wherein the coolant support member is provided with a thermal barrier (liner) to create a temperature gradient to enable the payload area to be maintained at a temperature above the sublimation temperature of the coolant.

14. The container according to claim 1, wherein the side and end panels are provided by way of a U-section single panel, to provide a more resilient structure.

15. The method of assembling a transport container per claim 1, comprising the steps of: assembling the container; filling the coolant volume with a required amount of coolant for an anticipated journey and/or storage period after opening a cover or prior to closing the cover; closing the cover; permitting stabilization of temperature within the container to the required degree; loading the container with a temperature sensitive payload; closing a payload aperture; securing the panels together; maintaining the payload at the desired temperature; and removing the payload when desired at the appropriate time after removing panel secure men means and opening the door.

16. The method according to claim 15, further comprising the steps of: opening the cover after removing additional panel securement means; filling the coolant volume with a required amount of additional coolant for an additional period of time; closing the cover; and maintaining the payload at the desired temperature for an additional period of time.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0021] For a better understanding of the present invention, reference will now be made, by way of example only, to the Figures as shown in the accompanying drawing sheets, wherein:

[0022] FIG. 1a illustrates an exploded perspective view of an embodiment of the teaching to U.S. Pat. No. 8,763,423B2;

[0023] FIG. 1b illustrates a perspective view of an embodiment of the teaching to U.S. Pat. No. 9,688,455B2, with a cover and one end panel removed;

[0024] FIG. 1c illustrates an exploded perspective view of an embodiment of the teaching to US20180362243;

[0025] FIGS. 2a, 2b & 2c comprise side and first and second end views of an embodiment of the invention;

[0026] FIG. 2d shows a representation of a vacuum insulation panel;

[0027] FIG. 3 shows a container made in accordance with the invention with a lid in a spaced apart fashion from top edges of the side panels defining the container, with an end panel separated in a laterally spaced apart fashion from the container body;

[0028] FIG. 4a shows a plan view of an embodiment of the invention prior to the top cover element being placed upon the container;

[0029] FIG. 4b shows a cross-sectional view through the longer length sides of an embodiment of the container pe FIG. 4a;

[0030] FIG. 4c shows a cross-sectional view through the short length sides of an embodiment of the container pe FIG. 4a;

[0031] FIGS. 5a-5d detail certain aspects of an embodiment of the invention;

[0032] FIGS. 5e-5h disclose features of the coolant support and temperature monitoring elements of the present invention;

[0033] FIG. 6a comprises a temperature plot over time in respect of a test shipment;

[0034] FIG. 6b details the period of time for the components defining a payload volume of an embodiment of the invention to show a further design of insulating sheet spacer having round apertures as used in fourth and fifth embodiments of the invention;

[0035] FIGS. 7a-7d indicate four steps associated with an initial temperature conditioning of an container in accordance with an embodiment of the invention;

[0036] FIG. 7e shows a graphical representation of the density of carbon dioxide with respect to various temperatures and pressures;

[0037] FIGS. 8a-8d show the steps associated with the loading of a payload; [0038] an initial temperature conditioning of an container in accordance with an embodiment of the invention;

[0039] FIGS. 8e-8g show the steps associated with the provision of extra dry ice to permit an extension in the period of operation of the container in use;

[0040] FIGS. 9a-9c show the steps associated with a removal of a payload in accordance with an embodiment of the invention;

[0041] FIG. 9d shows how a payload is transferred with respect to a container in accordance with the invention; and

[0042] FIG. 10 shows a graphical representation of carbon dioxide Prandtl number at varying temperatures and pressures;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] There will now be described, by way of example only, the best mode contemplated by the inventor for carrying out the present invention. In the following description, numerous specific details are set out in order to provide a complete understanding to the present invention. It will be apparent to those skilled in the art, that the present invention may be put into practice with variations of the specific.

[0044] FIG. 1a shows an example of an expanded spaced apart arrangement of a pallet shipper as is in common use in the field of cold chain logistics. Payload 11 is placed upon a pallet assembly 12 and surrounded by a base, side and uppermost insulation-structural panels 13, the panels being arranged to couple together in a resilient, draught free fashion. The panels are preferably further retained by straps (not shown). The payload 11 is maintained in a sealed environment with coolant items 14 associated with the inside wall panels and an intermediate spacer-insulator panels 15. Payload 11 is conveniently supported upon a pallet base (not shown). Whilst a base panel is not shown in any detail, outwardly extending the L-section corner sections 16 (to be referred to as L-members hereinafter) are used to assist in mutual securement of adjacent panels. FIG. 1b shows a partially completed container arrangement in accordance with U.S. Pat. No. 9,688,455B2, with a cover and one end panel removed. FIG. 1c illustrates an perspective view of an embodiment of the teaching to US20180362243, part cut-away to show the interior. In FIGS. 1b and 1c, respectively, there are apertures 18 at the base to enable the tines of a forklift or similar lifting device to enable the whole container 15 to be simply and conveniently moved, from a loading area to an aircraft or other transport vehicle or storage place for transport and/or storage.

[0045] Referring now to FIGS. 2a-2c, there are shown three different aspects of the present invention in a completed container with product retained therewithin, showing an assembled shipper, respectively: view of left; view of front; and view of rear. With reference to FIG. 3, which shows a container in a substantially complete stateexcept the cover element is raised and the access door panel is presented in a laterally spaced apart fashion with an intermediate container assembly 30 shown, as would typically be carried within, noting that in transferring goods from a shipper at a transport facility goods-unloading area the temperature will not be ultra-low and the product will need to be transferred to a controlled temperature refrigerated area for onward transport and distribution or further processing. The shipper comprises multi-layer panels 21-26 as shall be discussed below, each with a rugged, optionally reflective finish, with L section edge corner elements 27 along the twelve corners between mutually orthogonal intersections of adjacent panels, to make a provide an airtight fastening between adjacent abutting edges of the orthogonal panels 21-26. The L section elements 27 are placed along the mating portions of respective edges, with sufficient allowance to prevent overlap of orthogonal members at adjacent corners.

[0046] It is believed that the L section members enable strapping forces to be spread along edges, to enable the edges to be effectively gas-tight, to prevent loss/exchange of heat with any exchange of gases. Equally, the L section members provide rigidity when handling elements and provide durability wen providing corner protection. The L section elements are conveniently formed from aluminium sheet of the order of 1-4 mm in thickness for lightnessespecially if formed from the readily available 600 grades although, for example, they could also be formed from stainless steel such as 304, 316, as indeed they could be formed from other metals. Such metals when in the form of a sheet can be pressed into a general L shape, as widely recognized. However, it will be appreciated that aluminium sections can also be extruded as, indeed, can many plastics, such as or ABS and UPVC. In any event, once formed, the L sections are attached to one panel and in conjunction with the edge (as determined by a Z or orthogonal axis to the planar panel) form a general U shaped channel into which a Z axis edge of a correspondingly placed orthogonal adjacent panel may be received. There may be a rebate associated with the edge and or channel. Additional sealing may be provided by a separate resilient member such as a closed cell rubber foam, providing a gas-tight resilient seal.

[0047] The multilayer panels have been developed to provide a very low thermal conductivity. Such multilayer panels are commonly used in thermally-controlled packaging, comprising two main components: a fiberglass core vacuum insulation panel (VIP) made with a metallized film envelope, and a polyurethane encapsulation layer for protection. Multilayer panels are available from a number of sources; Applicant tests have been performed with products from Avery Dennison; their panels have maximum dimensionsfor 60 mm (2.36) thicknessof 1.8 by 3.8 m, conveniently providing suitably large sheets for the manufacture of pallet shippers, noting that many pallet shippers measure: 1.2 m0.8 m0.71 m with larger models being 1.2 m1 m1.55 m, with pallet in pallet shippers having a larger footprint such as 1.88 m1.25 m1.1 m. The thermal conductivity is extremely low and typically of the order of 0.0042 W/mK for such PU-VIP panels, with corresponding R-values of 8 m.sup.2K/W. It is noted that a 35 mm thick panel of vacuum insulation is considered to be equivalent to 180 mm of glass fibre/170 mm of mineral wool (such as Rockwool)/160 mm of expanded polystyrene/or 145 mm of polyurethane in terms of thermal transmission/insulationmeaning less material is required for insulation, enabling more payload volume or reduced package dimensions. FIG. 2d shows a representation of a VIP panel 17 comprising a rigid encapsulation layer 18, a barrier envelope formed from vacuum metalized PET-based laminate 19; the core comprises a vacuumalthough a getter/desiccant (not shown) may be conveniently be employed to reduce any trace elements.

[0048] In the assembly or fabrication of a container in accordance with the invention, it has been found convenient to provide the base panel with four upstanding channels as determined by the placement of four L shaped members, with the top panel provided with a similar arrangement, but downwardly facing channels. It will readily be appreciated that the four upstanding wall panels can be arranged such that their lowermost edges engage within the upstanding U channels. It has been found that it is preferred to have the narrower upstanding side panels to be provided with two L section members whereby, subsequent to placement of the wider upstanding side panels, the narrower end panels can have their lowermost edge parts inserted into their respective base panel upstanding channels, whereupon upon pivoting within the base channel, the upper edge portions of the wider edge panels are brought into contact with the corresponding U shaped channels upstanding either side of the end panels.

[0049] Per FIGS. 2a, 2b & 2c, for each of the three axis there are provided webbing 28 fastened by strapping mechanisms 29 such as ratchet web trapping mechanisms as are well known, to retain the panels together. The straps shown comprise re-useable strapping mechanisms. Single use strapping can be employed, with the ends of each strap being fastened to each other, conveniently using an elongate crimp fastener, as is known. Whilst a number of different widths of webbing such as woven polyester webbing can be used, it has been found that 50 mm (2) webbing has been sufficient to ensure that forces are uniformly applied to ensure that the components are properly sealed, noting that if unequal forces are applied, gaps between adjacent panels could arise, which would compromise the integrity of the seals between adjacent panels of the container and thus permit temperatures to be at variance with design. It has been found to be helpful to have marked distinct areas, as determined by plastics sticky-tape or otherwise to indicate the general positioning of the webbing. If using a thinner strap, it may be useful to have more straps, for example nine or sixteen as opposed to six; equally it may be appropriate to have more straps along the panels of greater length. Ideally the webbing is of a non-rip configuration.

[0050] Turning now to FIG. 4a, it can be seen that in an area above the payloadoccupied by a receptacle/container 33 (noting that this figure shows the container 33 and opening wall panel or door panel 25 transposed laterally from a closed position) there is a tray 32 for receiving a coolant such as dry ice; this tray can be supplemented by further pockets 33 depending from or otherwise separately existing to provide additional cavities for the placement of dry ice or other coolant. The tray may be moveable or may be fixed. The dry ice may be loose or be supplied in shaped containers (cassettestyle), to facilitate placement; however the containers may provide difficulties in assessing an amount of dry ice present, noting that, for air transport, the International Air Travel Association (IATA) limits the amount of dry ice that can be carried in a single transport unit or container to 200 Kg. Notwithstanding the above, it has been found that loose pellets of dry ice can be conveniently added noting that personnel must be protected from direct skin contact with dry ice. The amount of dry ice visible upon the surface may indicate whether or not a further amount of dry ice is required if the shipper in accordance with the invention is subject to checks in the event that partial loads are removed from the payload receptacle 30 during a delivery transit. The payload space can accommodate either hand or pallet loaded payloads, the latter of which facilitates expedited pack out process times to ensure temperature sensitive materials are not exposed to excessive time out of environment events. It will be appreciated that if the container is not to be transported by aircraft, then the amount of dry ice can be increased, increasing the period of transport and/or storage or period until the next replenishment.

[0051] FIG. 4b represents a cross-sectional view through line B-B of FIG. 4a. It can be seen that there is a frame 45 of thickness T spanning from an inside face of panel 22 to provide an inside surface for the payload. This frame has been conveniently been formed from aluminium of 3/16 thickness and support the lower portions of the dry ice cavities 33; an upper section 46 supports the upper tray, noting that the tray and side elements (panniers or so-called saddle-bag containers) are lined with a thermal barrier material that can control the temperature of the payload volume by providing a thermal drop TD in relation to its thickness. Accordingly dry ice, for example, at 78.5 C. using a thermal liner presenting a temperature gradient of 4 C. presents a cooling temperature within the payload volume of approximately 75 C., suitable for maintaining one intended product lipid Nano-Particles (LNP) at an appropriate temperature, noting that the payload carton 30 is required to be kept within a temperature range of 80 C. and 60 C.

[0052] Returning to the tray 32 for receiving a coolant such as dry ice Applicants have employed a plastics bubble foil insulation, sometimes referred to as an aluminized plastics bubble-sheet. Applicants have employed their own bubble foil insulation, which is available under the SilverSkin brand. Two thicknesses of bubble sheeting are readily available, being of 3 mm and 7 mm in thickness, which comprise single layer bubble sheet and double layer bubble sheetbut can be used in multiple layers, to pre-determine a specific change in temperature T C. The aluminized bubble-sheet can provide by way of thermal reflectance and thermal conduction a considerable temperature drop. Accordingly, by the use of a suitable number of sheets of thermal insulation and reflectance together with the use of dry ice, a payload temperature can be maintained, for example, in ranges of 10 C. to 20 C., 15 C. to 25 C., whereby specialty chemicals can be transported in such temperature ranges with regard to the reflectivity of 97% and a weight of insulation of 306 gsm/226 gsm for insulator sheet thicknesses of 7 mm/3 mm respectively. Reference numeral 47 indicates a surface of the liner to the frame which is conveniently apertured to enable movement of gaseous particles within the payload volume. The frame 45 is simply formed from aluminium to maintain lightness of the system. The apertures mean that the payload gas circulation volume is improved by the extra volume provided by region 43. It will be appreciated by using one or more insulating sheets, a temperature drop across the insulating sheets can determine the temperature within the payload volume.

[0053] FIG. 4c shows the container in cross section through its longer length it will be noted that the first and second end sections are provided with thicker degrees of insulation, whereby recesses may be provided for thermal monitoring systems and recesses can be provided for the ratchet straps, whereby to reduce chances of disturbing strap tension though mis-handling or otherwise of the containers in use, especially during handling by fork-lift trucks, noting that gaps 48 under the container permit simple handling at ports, airports and when required to be placed upon other types of vehicles.

[0054] FIG. 5a shows the frame 45 in greater detail, since panels 22, 24 and 26 are not present. Panel 25 shows data-logging devices 35, which are connected by wires 34 to probes not shown, but fitted to an inside part of the framework 45 to enable temperature sensors to be placed and maintained in the same position. Whilst apertures are provided on the upper sheet 32, the inside walls of the payload volume are not so apertured. The container in FIG. 5b is arranged 180 relative to the container present in FIG. 5a, with both side panels 22 and 23 present. Dry ice support tray 32 is also shown. The container in FIG. 5c is shown complete but without the straps, present in FIG. 5d, noting that, for simplicity, the L section elements 27 are not shown. It will be appreciated that other sensors can be provided and with regard to the interior pressures, monitoring to ensure satisfactory heat transfer characteristics within the payload volume are maintained. FIG. 5e is an example of a container with entry panel 24 and top panel 26 not in place, indicating load 30, with the dry ice tray being provided with a thermal barrier sheet 32.

[0055] FIG. 5f shows temperature monitors 50 which reach out into the dry ice receptacle and barrier layer 32, 32. Reference numeral 34 indicates depending panniers or saddle bags which extend from the dry ice tray 32although they could be distinct containers, noting that the side cavities of the container are also indicated in FIGS. 4a and 4b. Referring now to FIG. 5g, temperature sensor lead wires 52 pass from the data loggers/temperature indicators 50 to temperature sensors 56 situated in upper corners of the container. For redundancy purposes at least two temperature sensors are provided. It will be noted, per FIG. 5g, that the temperature sensor leads 52 are enclosed in a mechanical protective conduit, to protect the wires from damage during replenishment of the dry ice, noting that in view of the ultra-low temperatures experienced in use, the wires will tend to become brittle as a glass temperature of the wires is approached. FIGS. 5h and 5i show, respectively a close up and general view of the placement of temperature sensors 56 within a payload volume of a container in accordance with the present invention.

[0056] FIG. 6a shows the results of an early test which indicates that a pallet shipper was transported over a period of 170 hours duration. FIG. 6b shows a transition time for a container in accordance with the invention to be filled with dry ice and a conditioning time of 1 hour 26 minutes was indicated.

[0057] In order to enable the shipper to be deployed at it is desired temperature range, the shipper must first be conditionedthat is to say the product must be assembled and brough to a selected operational temperaturewithout placing any payload therein, but filling the dry ice receptacle member or members with a quantity of dry ice. The steps associated with conditioning are made with reference to FIGS. 7a-7d. With regard to FIG. 7a, the lid 26 of the container is removed, conveniently using handlesa task which benefits from having at least two personnel present. Dry ice is pouredin the requisite amount (noting the commercial aircraft limit of 200 Kg if air travel anticipated) and the dry ice receptacles (downwardly extending pockets associated with two side wall, optionally threenoting that a downwardly extending pocket does not extend on the inside of the door member 24, since this is removed to enable placement of payload within the container and subsequent removal therefrom. FIG. 7b represents the placement of the desired quantity of dry ice, noting that if the shipper is going to be airborne during part of its journey, then there is a limit of 200 Kg of dry ice that may be present in the shipper. It will be appreciated that by releasing the straps extending over the top panel 26 and by removing the panel 26, the addition/replenishment of dry ice enable the placement of dry ice about the whole area of the support surface and enables the dry ice to be placed simply and conveniently into the depending side cavities, to ensure that the desired temperature of the payload volume is maintained, which would not be possible with small apertures as known in the art. In placing the dry ice in the pockets and top surface, personnel should take care to fill side cavities and finishing by levelling the dry ice (conveniently provided in the form of pellets) to enable uniform cooling effect and to permit the lid to be replaced per FIG. 7c is

[0058] In view of a particular desired operating temperaturenoting that it is primarily designed for use with dry ice which sublimes at 78.5 C.then thermal gradient sheets may need to be placed to between the dry ice and the payload volume, whereby to separate the lower temperature payload volumefrom the atmosphere above the dry icetaking into account that the higher the temperature of carbon dioxide (as a gas) it will rise. The thermal gradient sheets may also be referred to as thermal barrier layers. In one test, the thermal liner created a temperature gradient of approximately 4 C., thus ensuring the payload area is maintained at approximately 75 C. and therefore keeping a sample product safely within a design temperature range of 80 C. to 60 C. temperature range during transportation. Referring now to FIG. 7e, there is shown the density of carbon dioxide at varying temperature and pressure. Once the required amount of dry ice has been placed within the container, the lid 26 is returned to the top of the containerper FIG. 7d and the inside temperature is allowed to settle to a quiescent state (for a given volume of dry ice such that the internal temperature is correct).

[0059] Whilst the speed of temperature drop can result in temperature equalization within two hours, given that extremely valuable goods can be carried, conditioning periods of five hours are recommended, noting that during tests, periods of the inside temperatures remaining within a required range for periods in respect of fifteen, exercising caution with regard to the value of the product will not compromise any expected normal expected transit time, noting that it will always be possible to provide additional dry ice to the dry ice receptacle and downwardly extending panniers, whereby to extend the duration of the container operating at prescribed temperaturesubject to a continuing availability of dry ice. This procedure is commonly referred to as Re-icing in the cold chain industry and with regard to the present invention, with the lid removed the dry ice receiving volumes can be replenished with pellet dry ice, thus ensuring the temperature-sensitive payloads can be protected for extended durations should there be delays in the transport lane. Referring, once again, to the receptacle for the dry ice it was noted that the receptacle frame was formed from aluminium, notwithstanding that it would be logical to replace the metal with a lighter plastics material. Indeed, it has counterintuitively been determined that by the use of the thermally conductive metal, the period for conditioning is reduced and that the temperature within the payload volume is particularly uniform. It is believed that the uniformity is due in part to the receptable for the dry ice being formed from the highly thermally conductivenamely aluminium (although other metals such as stainless steel would provide similar results), together with the apertures present therein which enable a flow of the gaseous atmosphere, whilst reducing the thermal capacity of the support (i.e. reducing thermal mass/thermal inertia). The apertures do not need to be of any particular shape, but are conveniently circular, noting that this is a common shape employed in pressed sheet metals and known techniques can be employed in the manufacture thereof.

[0060] The present invention provides a simplified method for rapid payload loading and unloading, especially, for example, a pallet based or pallet-style container. The shipping system utilises a novel method of containing the dry ice within the container, in an area separate to the payload volume. A metallic frameworkconveniently aluminiumsupports a dry ice loading area/refill area that allows the system to be pre-cooled with dry ice pellets; after a period of approximately five hours the front wall of the shipper can be removed to facilitate pallet loading. The framework is conveniently easily dismantled; nonetheless it is also becoming preferable for complete products to be transported as a whole unit, ready assembled, to ensure that issues with damage to single panels or missing parts does not occur. The dry ice support structure remains intact with the front wall removed and ensures a quick and efficient process for loading the pallet into the shipper, thus ensuring the temperature sensitive materials within the pallet do not experience prolonged periods of time out of environment events.

[0061] Referring now to FIG. 8a, once the temperatures within the container have reached an equilibrium state, the lid member is raised to a degree in order to enable the panel 24 to be removed, whereby to enable a sub-container 30 of a low temperature payloadper FIG. 8bwhich payload is typically removed from a refrigeration system by means of a fork-lift truck or pallet trolley (not shown). In order to close the opening front panel 24, the lid needs to be removed. In a further development, the L shaped member is hingedly attached to the upper surface of the top cover 26, whereby to enable the panel 24 to be pivoted about its lowest edge with respect to the base channel as provided by base insulator member 21. Once the panel has been within the channel defined by the upper L shaped member (whether hinged or not), the straps are secured as indicated by FIG. 8d. It has been found preferable to attend to the vertical straps about the narrow sides initially, to be followed by the horizontal straps and then the vertical straps about the wider side panels. It may also be prudent to repeat the process, since the will be a degree of resilience; once the forces are applied evenly, each angle board associate with a certain panel will be uniformly positioned against their respective adjacent panels. FIGS. 8e-8g indicate the procedures required to replenish a coolant during a journey or period of storage; as can be seen from FIG. 8e, the lid 26 can be raisedonce the straps extending over the top have been removedthis has the benefit that full access is provided to the area where dry ice is required, yet the door to the enclosed payload volume is not disturbed, so that there is no distinct change of atmosphere within the payload volume. Moreover the replenishment of dry ice of other coolant can be performed in a matter of tens of seconds and certainly within a period of time short enough not to cause a temperature excursion within the payload volume. The skilled man will appreciate the benefit of being able to relation a coolant without disturbing the payload a volume of coolant media immediately surrounding in the payload volume.

[0062] It will be appreciated that removal of a payload 30 from a container as indicated in FIG. 9a is accomplished by removal (or at least reducing the tension to permit the door panel 24 to be removed and the upper panel 26 to be raisedat least to enable the door panel 24 to be initially hingedly opened and then removed from the load bay, to permit removal of payload container from the container, per simplified drawing 9c and with the aid of a fork-lift truck per FIG. 9d.

[0063] The present invention also provides several benefits that it is believed have not been truly realized before in a cold chain system and provides a controlled egress of carbon dioxide through a valve mechanism. As has been disclosed above, the six panelsas employed for a convenient industry-standard regular rectangular shaped boxhas adjacent edge panels mating within generally U shaped channels. With respect to each set of mating components along all twelve edges of the rectangular box, at least one face of the U channel or edge member received within the U channel associated with each edge is provided with a seal. The seal is conveniently provided by means of a closed cell foam. Such foams can be formed from polyolefin crosslinked foams and engineering polymers, as are known from Zotefoams, available under their AZOTE brand, which comprises sealed, nitrogen filled foam which are consistent in size and structure, preventing egress of carbon dioxide across such edges. Closed cell foam is defined as a cell totally enclosed by its walls and hence not interconnecting with other cells. Closed cell foam is usually made by subjecting a rubber compound to a gas, such as nitrogen, under high pressure. Closed cell foam offers a wide variety of material and density options. EPDM, neoprene, EPDM/CR/SBR, and PVC/NBR are a few common types of closed cell foams, which can range in densities from 6 lb/ft3 (soft) to 19 lb/ft3 (hard). Presently, the density employed is classed as mediumbeing a trade-off between durability and the provision of an effective seal between panel components which are in themselves relatively rigid, noting that, as discussed above include relatively fragile vacuum insulation panels incorporated within a polyurethane foam encapsulation, ideally faced by a glass-fibre to provide a good degree of resilience to maintain integrity as containers are manoeuvred using fork-lift trucks, often operating in enclosed spaces with little room for error.

[0064] As is known to those skilled in the cold chain industry, the Prandtl Number is an important indicator of heat transfer performance. The Prandtl NumberPris a dimensionless number approximating the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivityand is often used in heat transfer and free and forced convection calculations.

[0065] The Prandtl number can be expressed as:

[00001]$\mathrm{Pr}=\mathrm{Cp}/k$ [0066] where [0067] =absolute or dynamic viscosity (kg/m s, Ibm/(ft h)) [0068] Cp=specific heat (J/kg K, Btu/(lbmoF)) [0069] k=thermal conductivity (W/m K, Btu/(h ft2oF/ft))

[0070] With reference to FIG. 10, a graph of Prandtl number versus temperature is shown for various pressures: 1 bar, 10 bar, 50 bar and 100 bar. Separately calculated, at 55 C. and 100 bar, the Prandtl number is 2.8; at 55 C. and 50 bar, the Prandtl number is 2.78; and at 55 C. and 10 bar, the Prandtl number is 2.77. Given that the higher the Prandtl number, the better momentum diffusivity dominates and provides an improved degree of heat transfer, it is believed to be important to raise the internal pressure within the container, to improve heat transfer therein. Accordingly, Applicants have attempted to control the internal pressure with a couple of types of valves with relatively high blow-off pressures of several atmospheres. Notwithstanding the relatively complex situation, a simple valve has been defined by having one or more slits defined in the closed-cell edge sealant members and this provides a completed shipper with a predefined controlled leak path for CO2 gas to vent through. The passage of gas can be controlled by determination of the weight of a side panel acting upon the seal or by means of strapping the surrounding band straps to a particular tension. Nonetheless, a separate gas valve could be provided, conveniently one that can have a release pressure capable of being varied. In view of the above calculations, internal pressures of 10 bar are believed to be provide a safe transport container with good thermal control results; whilst a slight bowing of the side panels has been noted with systems under test, but the rugged system has demonstrated a resilient and rugged cold chain container system.

[0071] Small values of the Prandtl number, Pr<<1, means the thermal diffusivity dominates. Whereas with large values, Pr>>1, the momentum diffusivity dominates the behaviour. For example, the Prandtl value for liquid mercury indicates that the heat conduction is more significant compared to convection, so thermal diffusivity is dominant. However, for engine oil, convection is very effective in transferring energy from an area in comparison to pure conduction, so momentum diffusivity is dominant.

[0072] Whilst the invention has been developed for use with vacuum insulation panels encapsulated in PU foam, it will be appreciated that user requirements may specify that recyclable materials should be employed in the construction of a container. Applicant Company is developing paper-based board that has good thermal conductivity values and these could be employed in place of VIP-PU panels. Single face corrugated sheet comprises a sheet of facing or liner material joined to corrugated medium, by the use of, typicallyfor wood-based sheet materialwater based glue on the crests of flutes, the liner is brought into contact and can be heated to set the glue. Corrugated paper boxes are cheap to manufacture and have desirable qualities of recyclability and low thermal conductivity, but are typically moisture absorbent but can be treated to make them substantially waterproof.

[0073] Pharmaceuticals, proteins, biological samples and other temperature sensitive products, including food items, are regularly shipped in containers throughout the year and are subjected to a wide range of temperatures. Though they are shipped in insulated containers and/or climate-controlled environments, the temperature stability of the shipping containers can be significantly improved by employing the panel structures of the present invention, whereby to provide a simple solution to the maintenance of temperature profiles for the transport and storage of temperature sensitive products.