Improvements relating to cargo covers

Abstract

A cargo cover (2) comprising: an evaporative cooling element (6) for evaporating water; and a structure (8) for defining a passage for air to flow over the evaporative cooling element to aid evaporation and removal of water therefrom in use. There is also disclosed a method of controlling the temperature of cargo with the cargo cover.

Description

[0001] IMPROVEMENTS RELATING TO CARGO COVERS

[0002] TECHNICAL FIELD

[0003] This invention relates to controlling the temperature of cargo. In particular, though not exclusively, this invention relates to cargo covers and to methods of controlling the temperature of cargo.

[0004] BACKGROUND

[0005] Many products are transported long distances as cargo and are required to be kept within defined temperature ranges during transport. Pharmaceutical products and perishable food products are examples of such products, as are certain electronic items. Products may be shipped by any known means, road, ship or air transport, and are usually packed on pallets for ease of handling during shipping. The palletised goods may be potentially subjected to wide temperature fluctuations during transport. For example, they may be held at relatively low temperatures in the cargo hold of an aircraft and then left outside prior to the next stage of their journey and be subjected to high incident radiation and high ambient temperatures.

[0006] Products which are particularly sensitive to temperature changes during transport may advantageously be palletised and then protected with a cargo cover. A cargo cover may, for example, cover part of a pallet, typically the four sides and top of the pallet or, by providing a protective sheet under the pallet may cover all six sides of the pallet.

[0007] Current thermally-insulating cargo covers include a range of materials which may be for example a simple, thin protective cover e.g. a single-layer sheet, which may carry a reflective surface, which provides a means of modestly attenuating the effects of external temperature fluctuations for example by reducing the direct influence of incident solar radiation.

[0008] Alternative commercially available cargo covers are made from multi-layer materials designed to provide more significant thermal insulation properties i.e. their thermal insulation values for example as measured by thermal resistance (R-value in m2.K / W), contribute to their performance in protecting pallet contents from excessive thermal fluctuations.

[0009] Many prior art cargo covers are moisture vapour impermeable, which can lead to undesirable condensation within the cover. There is hence a need for vapour permeable cargo covers. Such cargo covers are discussed and disclosed, for example, in WO2018 / 142133.

[0010] Temperatures in excess of 30 °C in the shade are now common in certain parts of the world. In direct sunlight such temperatures can reach >50 °C. This presents a major challenge for cargo covers, for example where sensitive goods need to maintain a temperature of 15 - 25 °C at all times.

[0011] It is known to incorporate phase change materials into cargo covers to maintain low temperatures for longer. However, when present in a quantity capable of addressing high temperatures, phase change materials can considerably increase weight and cost.

[0012] There remains a need in the art for alternative and improved temperature control of cargo. It is an object of the invention to address at least one problem associated with the prior art.

[0013] SUMMARY OF THE INVENTION

[0014] From a first aspect, the invention provides a cargo cover comprising: an evaporative cooling element for evaporating water; and a structure for defining a passage for air to flow over the evaporative cooling element to aid evaporation and removal of water therefrom in use.

[0015] Such a cargo cover can offer additional temperature control of cargo thanks to the evaporative cooling element.

[0016] Evaporative cooling is achieved by the conversion of liquid water into vapour using surrounding thermal energy, resulting in a lower temperature. Evaporative cooling is an isenthalpic process. The energy needed to evaporate the water is taken in the form of sensible heat, which affects temperature, and converted into latent heat, the energy present in the water vapor component, whilst enthalpy remains constant.

[0017] Air flowing through the passage aids evaporation and removal of water from the evaporative cooling element, allowing heat to be transported away.

[0018] It has been found that the drop in temperature resulting from evaporative cooling can aid controlling the temperature of cargo. Evaporative cooling has been found to be of particular benefit in high temperature environments, especially in seeking to maintain a suitable temperature for sensitive goods. Where desired, in some embodiments, evaporative cooling may be achieved passively, which facilitates portability and energy saving.

[0019] Advantageously, the passage for air may be across a top of the cargo cover. This allows for exposure of the evaporative cooling element at the top of the cargo and has been found to offer effective evaporative cooling.

[0020] Suitably, the passage for air may comprise a multi-directional airflow region to allow air to flow over the evaporative cooling element from a plurality of directions. Allowing airflow, for example from wind, to come from a plurality of directions enhances flexibility of use, particularly where passive operation is desired. For example, the airflow region may be open on lateral sides of the cargo cover to allow air to flow from and to a plurality of lateral directions. Suitably, the airflow region may be open on all lateral sides of the cargo cover to allow air to flow over the evaporative colling element from and to all lateral directions.

[0021] The structure may advantageously be arranged to shade at least part of the evaporative cooling element in use.

[0022] Suitably, the structure may comprise a guide for guiding air along the passage.

[0023] Advantageously, the guide may be opaque. This can help the guide shade the evaporative cooling element. Optionally, the guide may comprise a low emissivity outer surface, which can further help with temperature control. For example, the guide may comprise a metallised or white outer surface.

[0024] Optionally, the guide may permit passage of UV light whilst blocking light of other wavelengths at least in part. This may be advantageous for cargo comprising organic matter.

[0025] The low-emissivity surface may suitably have an emissivity of less than 0.5, preferably less than 0.3, more preferably less than 0.25 and most preferably less than 0.20. Emissivity expresses the amount of energy radiated by a material, matter or surface. An ideal material or surface emitting the highest theoretical level of radiant energy would have an emissivity, e, of 1 and an ideal material or surface emitting no radiant energy would have an emissivity of 0. In practice all objects have an emissivity between 0 and 1. All emissivity values (e) herein are given at a temperature of 25 °C.

[0026] In various embodiments, the guide may have a relatively lower emissivity outer surface, e.g. as defined above, and a relatively high-emissivity inner surface facing the evaporative cooling element. For example, the guide may comprise a black surface facing the evaporative cooling element.

[0027] The high-emissivity surface may suitably have an emissivity of at least than 0.5, preferably at least 0.7, more preferably at least 0.9.

[0028] Suitably, the guide may comprise a flexible material. For example, the guide may comprise a fabric, which may optionally be woven or non-woven. Flexible material in the guide can aid transportation.

[0029] Additionally, or alternatively, the guide may comprise a rigid material, which may be helpful in guiding air with greater precision. For example, the guide may comprise a panel, for example of plastic, wood or cardboard. The guide may also be formed from a laminate comprising a plurality of layers of material. Advantageously, such a laminate may be a flexible laminate.

[0030] Advantageously, the structure may comprise one or more spacers for spacing the guide from the evaporative cooling element.

[0031] Suitably, the one or more spacers may be sized to space the guide from the evaporative cooling element by a distance in the range of from 1 cm to 50 cm, optionally in the range of from 2 to 40 cm, or even in the range of from 3 to 30 cm, or indeed 5 to 15 cm.

[0032] Conveniently, the one or more spacers may be identically sized, for example to space the guide from the evaporative cooling element by a constant distance.

[0033] Suitably, the one or more spacers may comprise a bracket or post. Advantageously, the one or more spacers may comprise a compressible or extendable member. This can facilitate compact transportation of the cargo cover.

[0034] Optionally, the one or more spacers may be attachable to a base portion of the cargo cover, for example via one or more flaps thereof. Alternatively, the spacers may be designed to be floor standing, providing a frame that positions the guide with respect to the absorbent portion.

[0035] The evaporative cooling element may suitably comprise a water storage. Advantageously, the evaporative cooling element may comprise an absorbent water storage layer. Suitably, the absorbent water storage layer may comprise a polymeric foam material or a porous arrangement of fibres. Suitably fibres may be organic or synthetic. For instance, such a reservoir could be construction from natural cotton or hydrophilic polyester.

[0036] The water storage layer may be the sole water storage of the evaporative cooling element. It may, for example, be filled by pre-soaking.

[0037] Additionally, or alternatively, the water storage of the evaporative cooling element may comprise a tray. For example, the water storage may comprise an absorbent water storage layer within a tray.

[0038] A tray or surface for water storage may additionally or alternatively be provided by a base portion of the cargo cover.

[0039] Conveniently, the tray may be formed of a plastics material, suitable a fluted plastics material.

[0040] To aid air movement, the tray may advantageously comprise one or more openings in side walls of the tray. Optionally, the tray may permit passage of UV light whilst blocking light of other wavelengths at least in part. This may be advantageous for cargo comprising organic matter.

[0041] Optionally, the guide may comprise a recess or aperture for delivering water to the water storage. Suitably, the recess or aperture may have a largest diameter in the range of from 2 cm to 10 cm.

[0042] In some embodiments, water may be introduced on a continuous basis to the water storage by gravimetric means, suitably from a water storage container in fluid communication with the water storage. Optionally, the water storage container may be configured to release water to the water storage each time a hydrostatic head of the water storage sinks below a threshold.

[0043] To facilitate evaporation, the evaporative cooling element may advantageously comprise a wicking material. Suitably, the evaporative cooling element may comprise a wicking evaporation layer, optionally comprising a fibrous material, optionally cellulose or synthetic fibres.

[0044] In various embodiments, the absorbent water storage and the wicking material may be integral. This can be achieved, for example with a fibrous material, optionally a cotton flanellette. A layer of this material can provide integrated water storage and wicking.

[0045] The cargo cover may optionally consist of the evaporative cooling element and the structure. For example, a lid consisting of the evaporative cooling element and the structure is a useful cargo cover for controlling temperature at the top of cargo.

[0046] Alternatively, the cargo cover may comprise additional components.

[0047] The cargo cover may comprise a base portion. Suitably, the base portion may support the evaporative cooling element.

[0048] Additionally or alternatively the base portion may comprise insulation material for insulating cargo. Insulation can complement the cooling action of the evaporative cooling element.

[0049] Advantageously, the base portion may be shaped to locate the cargo cover on cargo, for example on a pallet of cargo.

[0050] Suitably, the base portion may comprise a rigid support for supporting the evaporative cooling element. For example, the support may comprise a tray within which the evaporative cooling element is held. Optionally, the support may comprise one or more formations or projections for locating the cargo cover with respect to cargo.

[0051] Advantageously, the base portion may comprise a top and lateral sides, and the evaporative cooling element may be supported by the top of the base portion.

[0052] Optionally, the top of the base portion may have a lower thermal resistance than the sides.

[0053] Advantageously, the sides may comprise insulation material.

[0054] Suitably, the base portion may be open-topped so that the evaporative cooling element can be brought into direct contact with cargo.

[0055] Advantageously, the base portion may comprise an insulation laminate, optionally a plurality of insulation laminates joined together. Suitably, the base portion may comprise one or more side laminates at sides of the base portion. Optionally, the base portion may comprise a top laminate at a top of the base portion.

[0056] Insulation laminates are known in the art. They may suitably comprise one or more insulation materials, for example interleaved low emissivity and air-entrapment layers, for example waddings.

[0057] Conveniently, the base portion may define a void for receiving cargo, optionally a cuboid void for receiving a cuboid pallet of cargo.

[0058] The base portion may advantageously include a phase change material. For example, the base portion may comprise one or more laminates, e.g. a top laminate and / or side laminates, incorporating a phase change material layer including a flexible insulation material comprising a flexible porous medium defining a pore volume, and a solid / liquid phase change material (PCM) within the pore volume.

[0059] The cargo cover may advantageously be in a deployed configuration with the structure defining a passage for air to flow over the evaporative cooling element to aid evaporation and removal of water therefrom in use. Water may be held by the evaporative cooling element to allow evaporative cooling to occur.

[0060] From a second aspect, the invention provides a method of controlling the temperature of cargo, the method comprising: covering the cargo with a cargo cover according to the first aspect of the invention with the evaporative cooling element holding water and the structure defining a passage for air to flow over the evaporative cooling element to aid evaporation and removal of water therefrom; and flowing air along the passage to evaporate and remove water from the evaporative cooling element of the cargo cover. Advantageously, flowing air along the passage may comprise exposing the passage to an environmental airflow. This could be provided, for example by wind or other air movement. Thus, flowing air along the passage may simply comprise positioning the covered cargo within an airflow. The method need not include active moving of air by a fan or the like, though of course the invention can embrace this where desired.

[0061] In some embodiments, the spacing and flexibility of the guide may also cause a venturi effect between the guide and the evaporative cooling element augmenting the evaporation effect.

[0062] Advantageously, the cargo may comprise perishable goods.

[0063] Suitably, the cargo may comprise goods that are required to be kept within a defined temperature range during transport, optionally at a temperature below 25 °C or even below 15 °C.

[0064] The method may comprise controlling the temperature of the cargo to remain within the defined temperature range whilst exposing the covered cargo to a temperature in excess of the defined temperature range.

[0065] In some embodiments, the cargo may comprise goods that are conditioned to a temperature below 25 °C, optionally below 15 °C or even below 10 °C. Such cargo may not have fixed temperature thresholds but can nevertheless benefit from low temperatures.

[0066] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and do not exclude other components, integers or steps. Moreover 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.

[0067] Preferred features of each aspect of the invention may be as described in connection with any of the other aspects. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible.

[0068] BRIEF DESCRIPTION OF THE DRAWINGS

[0069] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a sectional side view of a cargo cover in accordance with a first embodiment of the invention, deployed over a pallet of cargo;

[0070] Figure 2 is a plan view of the cargo cover of Figure 1;

[0071] Figure 3 is a graph showing temperatures measured in cargo;

[0072] Figure 4 is a sectional side view of a cargo cover in accordance with a second embodiment of the invention, deployed over a pallet of cargo; and

[0073] Figures 5 is a sectional view of a cargo cover in accordance with a third embodiment of the invention.

[0074] DETAILED DESCRIPTION

[0075] With reference to Figures 1 and 2, a cargo cover 2 in accordance with one embodiment of the invention comprises a base portion 4 supporting an evaporative cooling element 6 for evaporating water. A structure 8 of the cargo cover 2 defines a passage 10 for air to flow over the evaporative cooling element 6 to aid evaporation and removal of water therefrom in use.

[0076] The base portion 4 of the cargo cover is formed conventionally of insulation laminates 12 (one at the top and four at the sides) arranged to form a cuboid void within which cargo can be received.

[0077] A top of the base portion 4 supports the evaporative cooling element 6. The evaporative cooling element 6 comprises first and second layers of brushed cotton fabric (flannelette) 14. Between these layers is a layer of water absorbent nonwoven. The layers of the evaporative cooling element serve to absorb and wick water.

[0078] The structure 8 of the cargo cover 2 comprises eight compressible polymer blocks 16 which each act as spacers for suspending a guide 18 above the evaporative cooling element 6 at a distance of about ten centimetres. The blocks 16 are positioned at the points marked "X" in Figure 2.

[0079] The guide 18 comprises an aluminized film (with an emissivity of less than 0.1) laminated to a spunbond substrate. The film and spunbond laminate is held in position by a rigid frame fabricated from medium-density fibreboard (MDF). The laminate was glued to the outer edge of the frame so that from above only the aluminised surface was visible. The underside of the laminate was black and the underside of the MDF frame where visible was painted black so all that could be seen of the bottom of the guide was black. The guide 18 is mounted on the blocks 16 to present a metallised outer surface 20 and a black inner surface 22 facing the evaporative cooling element 6. The guide 18 is affixed to the base portion 4 of the cargo cover with hook and loop type attachments 24 such as Velcro ®.

[0080] The guide 18 shades the evaporative cooling element 6 and defines a multi-directional airflow region 10 through which air can flow over the evaporative cooling element 6 to aid evaporation and removal of water therefrom. This leads to evaporative cooling on the top of the cargo cover 2, helping to control the temperature of cargo received within the void of the base.

[0081] The incorporation of an evaporative cooling element 6 represents a fundamentally different approach to traditional insulation only approaches. Insulation-only cargo covers simply delay the change in temperature of their contents to the surrounding ambient temperature They are simply barriers to heat or cold of varying efficacy. The embodiment of Figure 1 both reduces the effect of sunlight by providing shade, and then actively cools the enclosed cargo to below ambient using a mechanism which requires no external power source and is thus safe for sensitive environments such as aircraft holds.

[0082] Using this embodiment, it was possible to sustain a steady state temperature of a cargo below ambient shade temperature for an extended duration.

[0083] A first pallet of cargo with the cover of Figure 1 was put out on a sunny day with a breeze rising to 5-10kts at pallet level and with very high light cloud appearing at 12.30

[0084] A second pallet of identical cargo with a cargo cover identical, save that the evaporative cooling element was absent, was put out alongside.

[0085] A third pallet of identical cargo with a cargo cover identical, save that the evaporative cooling element and the structure comprising the spacers and fabric were absent, was also put out alongside.

[0086] A temperature probe and data logger was placed under the cover between the cover and the cargo.

[0087] Temperatures were measured in each pallet of cargo over a period of about 6 hours. The results are shown in Table 1 and Figure 3.

[0088] Table 1

[0089] Pallet 1 maintained a significantly lower temperature than pallets 2 and 3.

[0090] Similar results were achieved with various temperatures and with variants of the embodiment in which the non-woven fabric sheet was replaced with wooden panels, plastic sheeting, and corrugated plastic all equipped with reflective surfaces on top and low emission surfaces below. It is beneficial that the guide 18 is reflective on its top face and black or similarly light absorbent on its lower face. Being able to flex (without structurally bending) is an advantage. The guide 18 seems to be most effective at a distance of about 9-10 cm from the evaporative cooling element.

[0091] Referring now to Figure 4, in a second embodiment of a cargo cover 100 in accordance with the invention, in which like reference numerals are used for like parts, the compressible blocks utilised in Figure 1 are replaced with brackets 102. The brackets 102 are made of metal or plastic and offer firm support and positioning to the guide. They are shaped to hold the evaporative cooling element 6 in position and serve as an anchor point to attach the guide to the cargo cover securely and quickly, for example using straps 104.

[0092] In this embodiment, a fabric flap 106 to serve as a wall was created around the top circumference of the cover 100 to hold any water that might leak from the evaporative cooling element 6.

[0093] With reference to Figure 5A and 5B, in a third embodiment of the invention, a cargo cover 200 takes the form of a rigid lid. In this embodiment there are no insulation laminates. The guide 18 is held in place by four feet disposed at corners of the cargo cover (not shown for clarity in Figure 5). The evaporative cooling element 6 is held in a rigid tray 202 having a side wall formation 204 that extends downwards to locate the tray 202 over a pallet of cargo 206. The tray also has an overhang 205 to help contain the cooling element 6. In this embodiment the tray 202 is placed directly onto cargo 206 by itself but it could alternatively be combined with side insulation laminates 12 and / or a top insulation laminate 12 as used in the embodiment of Figure 1.

[0094] Additional modifications are of course possible without departing from the scope of the invention. For example, it is possible to incorporate a water supply channel, for example taking the form of an aperture in the guide, or a supply tube or funnel.

Claims

CLAIMS1. A cargo cover comprising: an evaporative cooling element for evaporating water; and a structure for defining a passage for air to flow over the evaporative cooling element to aid evaporation and removal of water therefrom in use.

2. The cargo cover of claim 1, wherein the passage is across a top of the cargo cover.

3. The cargo cover of claim 1 or claim 2, wherein the passage comprises a multi-directional airflow region to allow air to flow over the evaporative cooling element from a plurality of directions.

4. The cargo cover of any preceding claim, wherein the airflow region is open on all lateral sides of the cargo cover to allow air to flow over the evaporative colling element from and to all lateral directions.

5. The cargo cover of any preceding claim, wherein the structure is arranged to shade at least part of the evaporative cooling element in use.

6. The cargo cover of any preceding claim, wherein the structure comprises a guide for guiding air along the passage, the guide optionally being opaque and / or comprising a low emissivity outer surface.

7. The cargo cover of claim 6, wherein the guide comprises a flexible material, optionally in the form of a fabric.

8. The cargo cover of claim 6 or claim 7, wherein the guide comprises a rigid material, optionally in the form of a panel.

9. The cargo cover of any one of claims 6 to 8, wherein the structure comprises one or more spacers for spacing the guide from the evaporative cooling element.

10. The cargo cover of claim 10, wherein the spacers are sized to space the guide from the evaporative cooling element by a distance in the range of from 3 cm to 30 cm.

11. The cargo cover of claim 9 or claim 10, wherein the one or more spacers comprise a bracket or post.

12. The cargo cover of any one of claims 9 to 11 wherein the one or more spacers comprise a compressible or extendable member.

13. The cargo cover of any preceding claim, wherein the evaporative cooling element comprises a water storage.

14. The cargo cover of claim 13, wherein the water storage comprises a tray, the tray optionally comprising one or more openings in side walls of the tray.

15. The cargo cover of claim 13 or claim 14, wherein the evaporative cooling element comprises an absorbent water storage layer, optionally comprising an open cell foam material.

16. The cargo cover of any preceding claim, wherein the evaporative cooling element comprises a wicking material.

17. The cargo cover of claim 16, wherein the evaporative cooling element comprises a wicking evaporation layer, optionally comprising a fibrous material, optionally cellulose fibres.

18. The cargo cover of any preceding claim, comprising a base portion shaped to locate the cargo cover on cargo.

19. The cargo cover of claim 18, wherein the base portion comprises a rigid support for supporting the evaporative cooling element and optionally one or more formations or projections for locating the cargo cover with respect to cargo.

20. The cargo cover of claim 18 or claim 19, wherein the base portion comprises a top and lateral sides, and wherein the evaporative cooling element is supported by the top of the base portion.

21. The cargo cover of any one of claims 18 to 20, wherein the base portion comprises an insulation laminate, optionally a plurality of insulation laminates joined together.

22. The cargo cover of any one of claims 18 to 21, wherein the base portion defines a void for receiving cargo, optionally a cuboid void for receiving a cuboid pallet of cargo.

23. A method of controlling the temperature of cargo, the method comprising: covering the cargo with a cargo cover according to any preceding claim with the evaporative cooling element holding water and the structure defining a passage for air to flow over the evaporative cooling element to aid evaporation and removal of water therefrom; andflowing air along the passage to evaporate and remove water from the evaporative cooling element of the cargo cover.

24. The method of claim 23, wherein flowing air along the passage comprises exposing the passage to an environmental airflow.

25. The method of claim 23 or claim 24, wherein the cargo comprises goods that are required to be kept within a defined temperature range during transport, optionally at a temperature below 25 °C.

26. The method of claim 25, comprising controlling the temperature of the cargo to remain within the defined temperature range whilst exposing the covered cargo to a temperature in excess of the defined temperature range.

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