Abstract:
There is provided a tray ( 20 ) for fruit or vegetables being foldable from a single piece of flat corrugated fiberboard ( 1 ), comprising: a bottom section having two long sides ( 11   a,    11   b ) and two end sides ( 12   a,    12   b ), wherein the panels of the corrugated fiberboard of the bottom section are parallel with the end sides; two opposed side walls ( 21   a,    21   b ) extending from the long sides of the bottom section; and two opposed end walls ( 22   a,    22   b ) extending from the end sides of the bottom section, wherein each side wall comprises two layers ( 13   a,    13   b,    14   a,    14   b ) of corrugated fiberboard having horizontal panels, each end wall comprises a middle section ( 23   a,    23   b ) and two flanking sections ( 24   a,    24   b ) flanking the middle section, said middle section being composed of a single layer ( 15   a,    15   b ) of corrugated fiberboard having horizontal panels and each flanking section comprising first ( 16   a,    16   b ) and second layers ( 17   a,    7   b ) of fiberboard having vertical panels and wherein the height of the middle section is less than the height of the two flanking sections.

Description:
TECHNICAL FIELD The present disclosure relates to the field of trays composed of corrugated fiberboard. In particular, it relates to such trays for fruit or vegetables. 
     BACKGROUND 
       [0001]    Fruit and vegetables are transported long distances around the globe. Normally, the fruit or vegetables are placed in trays for the transport. Often, the trays are composed of corrugated fiberboard. 
         [0002]    Today, Plaform provided by International Paper is the leading design of trays for transport and display of fruit and vegetables. In the Plaform design, the corrugated fiberboard in the bottom of the tray is arranged such that the panels extend in the longitudinal direction of the tray. 
       SUMMARY 
       [0003]    The inventor has realized that a result of the direction of the panels of the corrugated fiberboard in the Plaform design is that the long side walls are composed of board having horizontal panels, which is much less resistant to top to bottom load than side walls having vertical panels. Further, the inventor has found that the ventilation in stacks of Plaform trays is insufficient. 
         [0004]    The object of the present disclosure is to provide trays for fruit or vegetables that are strong and stable, stackable and cost efficient in the sense that they require relative small blanks of corrugated fiberboard and utilize the blanks efficiently. It is a further object to provide trays that allows for efficient ventilation and thus cooling of their contents when stacked, e.g. during transportation or storage. Another object is to provide a machine-erected tray (a tray formed in a machine). 
         [0005]    Therefore, there is provided a tray for fruit or vegetables being foldable from a single piece of flat corrugated fiberboard, comprising:
       a bottom section having two long sides and two end sides, wherein the panels of the corrugated fiberboard of the bottom section are parallel with the end sides;   two opposed side walls extending from the long sides of the bottom section; and   two opposed end walls extending from the end sides of the bottom section, wherein   each side wall comprises two layers of corrugated fiberboard having horizontal panels,   each end wall comprises a middle section and two flanking sections flanking the middle section, said middle section being composed of a single layer of corrugated fiberboard having horizontal panels and each flanking section comprising first and second layers of fiberboard having vertical panels and wherein   the height of the middle section is less than the height of the two flanking sections.       
 
         [0012]    The single piece of flat corrugated fiberboard from which the tray is folded is often referred to as a blank within the art. 
         [0013]    In the tray of the present disclosure, all parts of the walls that carry weight when the tray is stacked, i.e. the side walls and the flanking sections of the end walls, comprises two layers of board having vertical panel. The only parts of the walls that is composed only of board having horizontal panel, i.e. the middle sections of the end walls, are not in contact with the tray above in a stack and carries substantially no weight. For a tray having a length of 600 mm, a width of 400 mm and a height of 170 mm, the walls are composed of 3380 mm (3140 mm with ventilation cut-outs according to  FIG. 2 ) of board having vertical panel according to the present disclosure compared to only 1500 mm according to the Plaform design. 
         [0014]    Another benefit of the design of the present disclosure compared to the Plaform design or another design having the same direction of the bottom panels as the Plaform design is that the bottom deflection is decreased. 
         [0015]    The inventor has realized that when the middle sections are not necessary for carrying to top to bottom load, they may be designed to facilitate efficient ventilation instead. Therefore, the height of the middle section is less than the height of the flanking section such that air may be vented through the end wall. When stacks of trays are placed next to each other during transport, such ventilation is of particular importance as the temperature and humidity in the trays must be controlled for many products. 
         [0016]    Another benefit of reducing the height of the middle section is that the length of the blank from which the tray is folded is reduced. If the height of the middle section would be the same as the height of the flanking sections, the total length of the blank would increase by 8% for the most commonly used dimensions of the tray. Thus, the trays of the present disclosure may provide for a 8% reduction of board consumption in the manufacture of the trays, which is significant in this filed of relatively low margins. 
         [0017]    In an embodiment of the present disclosure, each flanking section further comprises a third layer of fiberboard having vertical panel. In such an embodiment, the height of the third layer is preferably less than the height of the first and second layers. Normally, that means that a lower portion of the flanking sections consists of three layers and an upper portion of the flanking sections consists of two layers. 
         [0018]    In a preferred embodiment, a single end wall component constitutes the middle section and the third layer of the flanking sections of each end wall. In such an embodiment, the upper edge of the end wall component may be straight and horizontal, which means that the height of the middle section is the same as the height of the third layer of the flanking sections. 
         [0019]    Preferably, such an end wall component extends from each of the end sides of the bottom section. Normally, a fold line separates each end wall component from the bottom section. 
         [0020]    In an embodiment of the present disclosure, at least one of the first and second layers is arranged outside of the third layer in the flanking sections of the end walls. Thus, if two trays are placed such that their end walls meet, an empty space between the trays is formed at the middle sections. If trays are stacked in this manner, an uninterrupted “chimney” is formed, which facilitates ventilation of the stack. When both the first and the second layers are arranged outside the third layer, a wider chimney is formed. 
         [0021]    When the third layer is sandwiched between the first and the second layer in the flanking sections, the first and the second layer, respectively, may be glued to the third layer. When the first and the second layers are both arranged outside of the third layer, only one of them may be glued to the third layer. In such case, the first and the second layer may be glued together. 
         [0022]    In the tray of the present disclosure, the width of a middle section may for example be 0.25-0.50 times the width of an end wall. 
         [0023]    Preferably, the tray of the present disclosure comprises handles. Normally, the handles are provided at the end walls of the tray. For example, handles may be formed by providing a cut-out in the middle section of each end wall. The cut-outs are typically 7-14 cm, such as 8-11 cm wide. In one embodiment, the width of the cut-out is less than the width of the middle section of the end wall. The height of the cut-outs is typically 2-5 cm, such as 2-4 cm. The shape of the cut-outs may for example be rectangular or elliptical. The end-portions/corners of the rectangle may be rounded. For example, the end portions may be half circles. 
         [0024]    In one embodiment of the present disclosure, the cut-out extends into the bottom section over a fold line between the bottom section and the middle section of the end wall. When such a cut-out is provided, a portion of the edge between the middle section of the end wall and the bottom section is thus removed. Such placement of the cut-out/handle facilitates ventilation of a stacked tray, in particular when a chimney if formed by arranging one or both of the first and second layers outside the third layer in the flanking sections. 
         [0025]    The cut out may for example extend between 0.5 and 5 cm into the bottom section. In one embodiment, it extends between 1 and 3 cm into the bottom section. 
         [0026]    Further, when the cut-out extends into the bottom section, a vertical channel is formed at the inside of the middle sections of the trays in a stack. Such a vertical channel is only interrupted by the contents of the trays. If the contents are not closely packed, which is normally not the case with larger fruits and vegetables, such a vertical channel provides for efficient ventilation (see Example 2). 
         [0027]    The cut-outs of the present disclosure are preferably positioned centrally in the end walls. That is, the distance from the middle of the cut-out to each edge between the end wall and the side walls is preferably the same. Thereby, the trays are balanced when carried. 
         [0028]    In one embodiment of the present disclosure, ventilation holes are provided in the bottom section at the long sides. Such ventilation holes may be matched by ventilation cut-outs in the side walls at approximately the same position along the long sides of the bottom section. Preferably, such ventilation cut-outs are positioned at the top of the side walls such that they are in close proximity to the ventilation holes of an overlying tray in a stack. When the ventilation cut-outs have such positions, a part of the upper edge of each side walls is removed. The proximity between the ventilation cut-outs and the overlaying ventilation holes facilitate the ventilation of the trays when stacked. 
         [0029]    At each long side, one or two or more ventilation holes may be provided in the bottom section. Likewise, one or two or more ventilation cut-outs may be provided in each side wall. In one embodiment, the positions along the long side of the bottom section of the ventilation holes and the ventilation cut-outs are matched. 
         [0030]    In one embodiment, the ventilation holes in the bottom section extend into the side walls. In another embodiment, the shortest distance from the edge of each ventilation hole to one of the long sides 1-4 cm, such as 1-3 cm. 
         [0031]    In one embodiment of the present disclosure, the height of the middle section of is approximately the same as or less than the width of each flanking section. This means that in the blank from which the tray is formed, the portion that corresponds to the middle section of the end wall, e.g. the single end wall component discussed above, does not contribute to the total length of the blank. In other words, by keeping the height of the middle section approximately the same as or less than the width of a flanking section, the total length of the blank is reduced, which saves material and thus costs. This is also discussed above. 
         [0032]    To distribute the top-to-bottom load on stacked trays, the height of the side walls may be approximately the same as the height of the flanking sections of the end walls. 
         [0033]    The bottom section is normally rectangular, but may is some embodiments be square. For example, the length of each long side may be 1.1-1.9, such as 1.3-1.7, 1.4-1.6 or 1.5, times the length of each end side. Each long side may for example be 300-1100 mm, such as 400-800 mm and each end side may for example be 200-700 mm, such as 250-550 mm. 
         [0034]    The skilled person understands that in the normal case, both end walls have the same dimensions and configuration and both side walls have the same dimensions and configurations. Likewise, the length of both long sides of the bottom section is normally the same and the length of both end sides of the bottom section is normally the same. 
         [0035]    The corrugated fiberboard of the present disclosure may have one or two or more corrugated (flute) layers. For example, it may have a BC-profile. 
         [0036]    Further, the corrugated fiberboard of present disclosure may comprise an outside liner and/or an inside liner and possibly a center liner. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    The invention is now described, by way of example, with reference to the accompanying drawings, in which: 
           [0038]      FIG. 1  shows an example of a blank that may be folded to form a tray according to an embodiment of the present disclosure. 
           [0039]      FIG. 2  shows a tray according to an embodiment of the present disclosure in a folded configuration. 
           [0040]    In  FIG. 3 , a blank that may be folded to a tray according to the present disclosure having a length of 600 mm, a width of 400 mm and a height of 170 mm ( FIG. 3A ) is compared to a blank that may be folded to a tray according to the Plaform design having he same dimensions ( FIG. 3B ). 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description. 
         [0042]      FIG. 1  shows a blank  1  from which a tray  20  according to an embodiment of the present disclosure may be formed.  FIG. 2  shows the tray  20  in the folded configuration. 
         [0043]    The blank  1  comprises a bottom section  10 , which will constitute the bottom of the folded tray  20 . The bottom section  10  comprises opposed long sides  11   a,    11   b  and opposed end sides  12 ,  12   b,  which are defined by folding lines in the blank  1 . 
         [0044]    Outside the folding lines defining long sides  11   a,    11   b,  the first side wall layers  13   a,    13   b,  which will constitute the outer layer of each side wall  21   a,    21   b  of the folded tray  20 , are found. 
         [0045]    The outer borders of the first side wall layers  13   a,    13   b  are, in addition to the folding lines defining the long sides  11   a,    11   b  of the bottom section  10 , defined by side wall edge folding lines  18   a,    18   b  and opposed first side wall end folding lines  19   a,    19   b.  Thus, in the first side wall layers  13   a,    13   b,  the folding lines defining the long sides  11   a,    11   b  are opposed to the side wall edge folding lines  18   a,    18   b,  which will form the upper edge  25   a,    25   b  of the side walls  21   a,    21   b.    
         [0046]    Outside the side wall edge folding lines  18   a,    18   b,  the second side wall layers  14   a,    14   b,  which will constitute the inner layer of each side wall  21   a,    21   b  of the folded tray  20 , are found. 
         [0047]    The outer borders of the second side wall layers  14   a,    14   b  are, in addition to the side wall edge folding lines  18   a,    18   b,  defined by the short ends  101   a,    101   b  of the blank  1  and opposed second side wall end folding lines  19   c,    19   d.  Thus, in the second side wall layers  14   a,    14   b,  the side wall edge folding lines  18   a,    18   b  are opposed to the blank short ends  101   a,    101   b,  which will meet the bottom section  10  at the long sides  11   a,    11   b  in the folded tray  20 . 
         [0048]    Outside the folding lines defining the end sides  12   a,    12   b  of the bottom section, end wall components  15   a,    15   b  are found. The end wall components  15   a,    15   b  will constitute the middle section  23   a,    23   b  of each end wall  22   a,    22   b  in the folded tray  20 . Further, the end wall components  15   a,    15   b  will constitute the third layer of each flanking section  24   a,    24   b  of the end walls  22   a,    22   b  of the folded tray  20 . 
         [0049]    Each end wall component  15   a,    15   b  is normally rectangular and only one of its sides is defined by a folding line (i.e. the folding lines defining the end sides  12   a,    12   b  of the bottom section  10 ). The other three sides are edges defined by cuts. 
         [0050]    Outside the first side wall end folding lines  19   a,    19   b,  the first flanking section layers  16   a,    16   b,  which will constitute the first (and normally outer) layer of the flanking sections  24   a,    24   b  of the end walls  22   a,    22   b,  are found. Each first flanking section layer  16   a,    16   b  is normally rectangular and only one of its sides is defined by a folding line (i.e. the first side wall end folding lines  19   a,    19   b ). The other three sides are edges defined by cuts. 
         [0051]    Outside the second side wall end folding lines  19   c,    19   d,  the second flanking section layers  17   a,    17   b,  which will constitute the second layer of the flanking sections  24   a,    24   b  of the end walls  22   a,    22   b,  are found. Each second flanking section layer  17   a,    17   b  is normally rectangular and only one of its sides is defined by a folding line (i.e. the second side wall end folding lines  19   c,    19   d ). The other three sides are edges defined by cuts. 
         [0052]    The second flanking section layers  17   a,    17   b  may be the inner layer of the flanking sections  24   a,    24   b  of the end walls  22   a,    22   b.  In such case, the third layer of flanking sections  24   a,    24   b  of the end walls  22   a,    22   b,  e.g. the end wall component  15   a,    15   b,  is normally the middle (sandwiched) layer. Alternatively, the end wall component  15   a,    15   b  may constitute the inner layer, while the second flanking section layers  17   a,    17   b  are sandwiched. This is further discussed below. 
         [0053]    The direction of the corrugation panels in the blank is parallel with the end sides  12   a,    12   b  of the bottom section  10 . As the first side wall layers  13   a,    13   b  are folded along the long sides  11   a,    11   b  of the bottom section  10  to a standing orientation, the panels in the in the first side wall layer will be standing/vertical. Further, when the second side wall layers  14   a,    14   b  are folded inwardly along the side wall edge folding lines  18   a,    18   b  such that the blank short ends  101   a,    101   b  meet the bottom section  10  at the long sides  11   a,    11   b  and the upper edge  25   a,    25   b  of the side walls  21   a,    21   b  is formed at the side wall edge folding lines  18   a,    18   b,  the panels in the second side wall layers  14   a,    14   b  will also be standing. 
         [0054]    Further, it follows from the above that the panels of the first  16   a,    16   b  and second  17   a,    17   b  flanking section layers will be standing in the folded configuration of the tray  20 . Thus, there will be double layers of standing panels in the side walls  21   a,    21   b  and the flanking sections  24   a,    24   b  of the end walls  22   a,    22   b.  The only parts of the walls that lack standing panel is the middle section  23   a,    23   b  of the end walls  22   a,    22   b;  each middle section  23   a,    23   b  of the end walls consists of a single layer having vertical panels in the embodiment of  FIG. 2 . 
         [0055]    In each end wall  22   a,    22   b,  the height of the middle section  23   a,    23   b  is less that the height of the flanking sections  24   a,    24   b.  To achieve this, the width w of the end wall components  15   a,    15   b  is less than the height h of the first  16   a,    16   b  and second  17   a,    17   b  flanking section layers. 
         [0056]    In the folded tray  20 , the width w of the end wall components  15   a,    15   b  become the height of the middle section  23   a,    23   b  of the end walls  22   a,    22   b.  Further, the height h of the of the flanking section layers  16   a,    16   b,    17   a,    17   b  becomes the width of the flanking sections  24   a,    24   b  of the end walls end the folded tray  20 . 
         [0057]    The machine direction of the board of the blank  1  is perpendicular to the direction of the panels (see  FIG. 3   a ). In  FIG. 1 , it is seen that the width w of the end wall components  15   a,    15   b  is selected such that they are not extending the length of the blank  1  in the machine direction. To obtain a tray in which the height of the middle sections  23   a,    23   b  is the same as the flanking sections  24   a,    24   b  in the end walls  22   a,    22   b,  the width w of the end wall components  15   a,    15   b  would need to be the same as the height h of the flanking section layers  16   a,    16   b,    17   a,    17   b,  which would increase the length in the machine direction of the blank by 8% for some typical dimensions of the tray. 
         [0058]    Handle cut-outs  102   a,    102   b  are provided at the folding line defining the end sides  12   a,    12   b  of the bottom section  10 . Each handle cut-out  102   a,    102   b  extends into the bottom section  10  and the part of the end wall component  15   a,    15   b  that constitutes the middle section  23   a,    23   b  of the end walls  22   a,    22   b  of the folded tray  20 . 
         [0059]    Ventilation holes  103   a,    103   b  are provided in the bottom section  10  at a shorter distance, e.g. 0.5-6 cm, from each long side  11   a,    11   b.  Further, ventilation cut-outs  104   a,    104   b  are provided at the side wall edge folding lines  18   a,    18   b  such that parts of the upper edge  25   a,    25   b  of the side walls  21   a,    21   b  of the folded tray are removed. Each ventilation hole  103   a,    103   b  is aligned with a ventilation cut-out  104   a,    104   b  such that a line through them is parallel with the end sides  12   a,    12   b  of the bottom section in the blank  1  and with the plane of the end walls  22   a,    22   b  in the folded tray  20 . 
         [0060]    Tab cut-outs  105   a,    105   b  may be provided in the bottom section  10  at the long sides  11   a,    11   b.  In such case, corresponding tab cut-outs  107   a,    107   b  are preferably provided in the second side wall layers  14   a,    14   b  at the blank short ends  101   a,    101   b  as well. Further, tabs  106   a,    106   b  may be provided by cuts at the side wall edge folding lines  18   a,    18   b.  Such tabs  106   a,    106   b  are aligned with the tab cut-outs such that they, in the folded configuration of the tray  20 , may lock with the tab cut-outs  105   a,    105   b,    107   a,    107   b  of an identical overlaying tray  20  in a stack. The tabs  106   a,    106   b  are preferably provided as extension of the second side wall layers  14   a,    14   b  such that they extend from the inner layer of the side walls  21   a,    21   b  in the folded configuration of the tray  20 . Further, the above positioning of the tab cut-outs  105   a,    105   b,    107   a,    107   b  provides tab holes  26  extending into the inner layer of the side walls  21   a,    21   b  in the folded configuration of the tray  20  that provide for excellent stability in a stack. 
         [0061]    In  FIG. 2 , the end wall components  15   a,    15   b  are sandwiched between the first flanking section layers  16   a,    16   b  and the second flanking section layers  17   a,    17   b  in the flanking sections  24   a,    24   b  of the end walls  22   a,    22   b.  Alternatively, all flanking section layers  16   a,    16   b,    17   a,    17   b  are arranged outside the end wall components  15   a,    15   b.  In such case, the free space between the middle sections  23   a,    23   b  of two trays  20  that are placed such that their end walls  22   a,    22   b  meet is doubled. 
         [0062]    In the shown in  FIG. 2 , the first  16   a,    16   b  and the second  17   a,    17   b  flanking sections layers are glued to the end wall component  15   a,    15   b.  When all flanking section layers are instead arranged outside the end wall component  15   a,    15   b,  the first flanking section layers  16   a,    16   b  are glued to the respective second flanking section layers  17   a,    17   b,  which in turn are glued to the end wall components  15   a,    15   b.    
         [0063]    Also, the first side wall layers  13   a,    13   b  may be glued to the second side wall layers  14   a,    14   b  for increased strength as movements of the layers  13   a,    13   b,    14   a,    14   b  relative each other in such case are prevented (or at least reduced). 
         [0064]    The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended claims. 
       EXAMPLE 1  
       [0065]    A tray according to the present disclosure (see  FIG. 3   a ) was compared to a tray according to the Platorm design (see  FIG. 3   b ). Both trays had a length of 600 mm, a width of 400 mm and a height of 170 mm. 
         [0066]    Both trays were composed a corrugated board in BC-profile, see Table 1. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Basic properties corrugated board 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Construction 
                 Substance 
                 Grade and producer 
               
               
                   
                   
               
               
                   
                 Outside Liner 
                 170 gsm 
                 Pure White, Billerud 
               
               
                   
                 Flute B 
                 140 gsm 
                 Billerud Flute, Billerud 
               
               
                   
                 Centre Liner 
                 140 gsm 
                 Billerud Flute, Billerud 
               
               
                   
                 Flute C 
                 140 gsm 
                 Billerud Flute, Billerud 
               
               
                   
                 Inside Liner 
                 200 gsm 
                 Petaliner, Peterson Moss 
               
               
                   
                   
               
             
          
           
               
                   
                 Properties 
                 Value 
                 Method 
               
               
                   
                   
               
               
                   
                 Caliper [mm] 
                 6.66 
                 — 
               
               
                   
                 ECT [kN/m] 
                 15.25 
                 ISO 3037 
               
               
                   
                 Sb MD [Mn] 
                 43.42 
                 ISO 5628 
               
               
                   
                 Sb CD [Nm] 
                 25.3 
                 ISO 5628 
               
               
                   
                 Sb GEO [Nm] 
                 33.1 
                 ISO 5628 
               
               
                   
                   
               
             
          
         
       
     
         [0067]    Blanks were produced in corrugated board (table 1) using a cutting table, Kongsberg XL 20 Power head. They were glued and assembled by hand and conditioned 48 hours in 20° C. and 90% RH prior to test. Box compression tests, BCT, were carried out according to ISO 12048 (1994) with one platen remained horizontal at all time during the test and the other platen were held by a universal joint at its center and free to tilt in any direction. To measure the ability of force transfer between bottom and top two boxes was placed in column when performing a BCT and is denoted as BCT ½. Bottom deflection was measured in accordance with UNE 49706. 
         [0068]    The results are shown Table 2 below. 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 PLAFORM ® 
                 Tray acc. to the 
               
               
                   
                 Property 
                 tray 
                 present discl. 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 BCT 90% RH  [kg] 
                 748 
                 1271 
               
               
                   
                 BCT ½ 90% RH  [kg] 
                 571 
                 1093 
               
               
                   
                 Bottom Deflection [mm] 
                 9.1 
                 8.0 
               
               
                   
                 Material [gram] 
                 686 
                 824 
               
               
                   
                   
               
             
          
         
       
     
         [0069]    The results show that the tray design according to the present disclosure results in a BCT 90%RH  that is 70% higher than for the Plaform design. Further, the BCT 90%RH  and in a simulated stack is 90% higher for the tray design according to the present disclosure than for the Plaform design. Bottom deflection is 12% lower for the tray design according to the present disclosure, which is beneficial. Further, the tray design according to the present disclosure only consumes 20% more material (area) and is thus more material effective than the Plaform design. 
       EXAMPLE 2  
       [0070]    In the trays of the present disclosure, handles may be formed by providing a cut-out in the middle section of each end wall. Such placement of the handles is beneficial as the middle sections carry no top to bottom load. 
         [0071]    The natural convection in tray stacks was simulated. In the simulation, a stack of trays in which the handle cut-outs extend into the bottom of the trays such that a vertical channel is formed at the inside of the end walls of the trays in a stack was compared to a stack of reference trays. 
         [0072]    In the reference trays, the handle cut-out was provided centrally in the middle section of the end wall. 
         [0073]    A tray with the handles extending into the bottom is shown in  FIG. 2 and 4   a  and the reference tray is shown in  FIG. 4   b.    
         [0074]    The simulations were carried out in COMSOL® and the following assumptions were made:
       only natural convection;   the trays are filled with melons consisting of 100% water; and   the initial temperature of the melons is 30° C. and the ambient air temperature is 0° C.       
 
         [0078]    The temperature and the flow were calculated simultaneously. In the calculations, the air flow is driven by temperature difference and the conjugate heat transfers occur. The maximum air velocity was limited to 0.1 m/s to provide comparable graphical representations. 
         [0079]    First, the simulations were limited to the end wall-end wall interface. The simulated velocity profile after three hours for the handle cut-out extending into the bottom is shown in  FIG. 5  and the corresponding velocity profile for the reference tray is shown in  FIG. 6 . 
         [0080]    Then, a whole stack was simulated. The simulated velocity profile after three hours for the handle cut-out extending into the bottom is shown in  FIG. 7  and the corresponding velocity profile for the reference tray is shown in  FIG. 8 . 
         [0081]    From the simulations, it is concluded that if the handle cut-outs extend into the bottom. the natural convection is more efficient and a vertical channel of high air flow is obtained in a stack of trays on a pallet.