Abstract:
An open refrigerated display case including: a refrigerated display area having one or more shelves; an air outlet and an air inlet opening into the display area and spaced from one another; a duct fluidically coupling the air inlet to the air outlet, the duct being configured to direct air flow out of the air outlet across the display area and toward the air inlet to form an air curtain across the display area; wherein each of the one or more shelves are provided with an associated flow stabilizing device; wherein the one or more flow stabilizing devices each include a cellular structure which extends transversely across the display area perpendicular to the direction of the air flow within the air curtain, the cellular structure forming a matrix of stabilizing channels; wherein the one or more flow stabilizing devices are each positioned so that the stabilizing channels receive the entire air curtain and stabilize the air flow within the air curtain; wherein an upper surface of the or each flow stabilizing device is arranged so as to be substantially level with or below an upper surface of the associated shelf.

Description:
BACKGROUND 
       [0001]    The invention relates to an open refrigerated display case and a flow stabilizing device for an open refrigerated display case. 
         [0002]    The display of chilled or frozen items is commonplace in many retail environments, most notably in supermarkets. Conventionally, such items have been displayed in refrigerated display cases having glass doors to allow customers to browse items before opening the doors to access the items. However, the presence of such doors has been seen as problematic in that they make it difficult for several customers to access the contents of the case, as well as providing an obstruction when open, narrowing the usable aisle space. 
         [0003]    It is therefore common for supermarkets to use open-fronted display cases (Open Refrigerated Display Cases; herein “ORDCs”). ORDCs utilize an air curtain which is cooled to below ambient temperature and propelled downward, across the open front of the display case. The air curtain separates the refrigerated interior of the display case from the ambient air surrounding the display case. The air curtain thus keeps the cool air inside the display case from spilling out due to buoyancy effects, and also provides a barrier from other external motions of air around the display case. ORDCs therefore do not need any physical barrier separating customers from the contents of the display case. Accordingly, ORDCs provide a desirable method of displaying food and other perishable goods as they allow both easy access and clear visibility of merchandise. 
         [0004]    However, as a direct consequence of their open design, ORDCs do have significantly higher energy consumption compared to the closed-fronted alternative. The main energy losses occur within the air curtain, and are caused by the entrainment of warm ambient air into the air curtain and the turbulent mixing which occurs within the air curtain itself. The entrainment of warm ambient air causes an increase in temperature within the air curtain, and this warmer air must be cooled as it re-circulates through the system. It has been estimated that 70% to 80% of the cooling load of an ORDC is due to such effects. 
         [0005]    In recent years, multi-decked designs have become commonplace to maximize the display space per unit of floor space. Consequently, the air curtains of such ORDCs must seal a larger display area. This has exacerbated entrainment issues and the resulting energy losses, as well as making the design of air curtains more challenging, particularly in respect of ensuring product integrity and temperature homogeneity while attempting to minimize their energy consumption. 
         [0006]    The invention thus seeks to improve the efficiency of ORDCs by reducing entrainment within the air curtain. 
       BRIEF SUMMARY 
       [0007]    According to an aspect of the invention there is therefore provided an open refrigerated display case comprising: a refrigerated display area comprising one or more shelves; an air outlet and an air inlet opening into the display area and spaced from one another; a duct fluidically coupling the air inlet to the air outlet, the duct being configured to direct air flow out of the air outlet across the display area and toward the air inlet to form an air curtain across the display area; wherein each of the one or more shelves are provided with an associated flow stabilizing device; wherein the one or more flow stabilizing devices each comprise a cellular structure which extends transversely across the display area perpendicular to the direction of the air flow within the air curtain, the cellular structure forming a matrix of stabilizing channels; wherein the one or more flow stabilizing devices are each positioned so that the stabilizing channels receive the entire air curtain and stabilize the air flow within the air curtain; wherein an upper surface of the or each flow stabilizing device is arranged so as to be substantially level with or below an upper surface of the associated shelf. 
         [0008]    The cellular structure is a honeycomb structure. 
         [0009]    The flow stabilizing devices may be spaced from the air outlet and/or one another by a distance which corresponds to approximately 4 to 6 times a width of the air outlet. 
         [0010]    The flow stabilizing devices may be spaced by a distance which corresponds to approximately 5 times a width of the air outlet. 
         [0011]    Each flow stabilizing device may be connected to the one or more shelves. 
         [0012]    Each flow stabilizing device may be pivotably connected to the one or more shelves. 
         [0013]    Each flow stabilizing device may be configured so as to allow a position of the matrix of stabilizing channels relative to the shelf to be varied. 
         [0014]    Each flow stabilizing device may be integrally forming in one of the shelves. 
         [0015]    The stabilizing channels may each have a uniform cross-section along their length (i.e. they are parallel-sided). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: 
           [0017]      FIG. 1  is a side cross-sectional view of a conventional open refrigerated display case (ORDC); 
           [0018]      FIG. 2  is a perspective view of a shelf having a flow stabilizing device according to an embodiment of the invention; 
           [0019]      FIG. 3  is a side cross-sectional view of an ORDC according to an embodiment of the invention having a plurality of shelves with flow stabilizing devices as shown in  FIG. 2 ; 
           [0020]      FIG. 4  schematically shows air flow from the conventional ORDC of  FIG. 1 ; 
           [0021]      FIG. 5  schematically shows air flow from the ORDC of  FIG. 3 ; 
           [0022]      FIG. 6  is a plan view of a shelf having a flow stabilizing device according to another embodiment of the invention; and 
           [0023]      FIG. 7  is a side cross-sectional view of an ORDC according to another embodiment of the invention having a plurality of shelves with flow stabilizing devices as shown in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1  shows a conventional ORDC  2 . The ORDC  2  comprises a cabinet portion formed by a lower wall  4 , a back wall  6 , an upper wall  8 , and left and right side walls (not shown). A lower panel  10 , a back panel  12  and an upper panel  14  are disposed within the cabinet portion. 
         [0025]    The lower, back and upper panels  10 ,  12 ,  14  form a display area  15  which is provided with a plurality of shelves  17  (six are shown) on which items may be displayed. The shelves  17  are affixed to the back panel  12 . 
         [0026]    As shown, the lower, back and upper panels  10 ,  12 ,  14  are spaced from the respective lower, back and upper walls  4 ,  6 ,  8  to form a duct  16 . An intake grille  18  is provided at the lower panel  10  to form an inlet to the duct  16 . Similarly, a discharge grille  20  is provided at the upper panel  14  to form an outlet from the duct  16 . The intake grille  18  and the discharge grille  20  are thus fluidically coupled to one another by the duct  16 . The intake grille  18  and the discharge grille  20  are spaced from the back panel  12  toward the front of the cabinet portion and ahead of the shelves  17 . 
         [0027]    A fan  22  and a heat exchanger  24  are located within the duct  16  adjacent to the intake grille  18  and thus are disposed between the lower wall  4  and the lower panel  10 . The fan  22  draws air into the duct  16  via the intake grille  18  which then passes through the heat exchanger  24  where it is cooled to well below the ambient temperature. 
         [0028]    After passing through the heat exchanger  24 , the air continues through the duct  16  between the back wall  6  and the back panel  12 . The back panel  12  is perforated allowing air to pass from the duct  16  into the display area  15  where it cools items located on the shelves  17  and on the lower panel  10 . 
         [0029]    The remaining air flows through the duct  16  to the discharge grille  20 . The air is ejected from the discharge grille  20  and descends over the open front of the display area  15  to form an air curtain  26 . The air curtain  26  passes from the discharge grille  20  to the intake grille  18 , where it is drawn in by the fan  22  and re-circulated through the duct  16 . The air curtain  26  thus forms a non-physical barrier which separates the display area  15  from the ambient air surrounding the ORDC  2 . 
         [0030]    As shown in  FIG. 1 , the air curtain  26  may be angled away from vertical by around 5-10°. This may be achieved by angling the discharge grille  20 . In particular, the discharge grille  20  may be provided with a honeycomb panel (not shown) which rectifies the air flow as it exits the discharge grille  20  to provide laminar flow. The air curtain  26  may also deviate away from the back panel  12  as a result of the air passing through the perforations in the back panel  12 . The intake grille  18  is therefore offset from the discharge grille  20  to allow for this. 
         [0031]      FIG. 2  shows a flow stabilizing device  28  according to an embodiment of the invention which is fitted to one of the shelves  17  of the ORDC  2 . 
         [0032]    As shown in  FIG. 2 , each shelf  17  comprises a shelf portion  30  and a pair of brackets  32  which support the shelf portion  30  and are configured to be received within slots in the back panel  12  of the ORDC  2 . A product information strip  34  extends across a front surface of the shelf portion  30  and has a channel for receiving tickets displaying information regarding the products on the shelf portion  30 , such as the product&#39;s price. 
         [0033]    The flow stabilizing device  28  comprises a pair of arms  36   a,    36   b.  The arms  36   a,    36   b  are affixed to either lateral side of the shelf  17  such that they are spaced from one another across the width of the shelf  17 . Each of the arms  36   a,    36   b  is connected at one end to the shelf  17  and extends away from the shelf  17  in a cantilevered manner to a free end. The arms  36   a,    36   b  thus lie in the same plane as the shelf  17 . The arms  36   a,    36   b  may be connected to the shelf  17  in any suitable manner, such as via attachment to the shelf portion  30 , the brackets  32  or the product information strip  34 . 
         [0034]    A pair of stabilizing beams  38   a,    38   b  extend between the arms  36   a,    36   b.  The stabilizing beams  38   a,    38   b  are spaced from one another and run parallel to one another across the full width of the shelf  17  (and the display area  15 ). The stabilizing beams  38   a,    38   b  are arranged so that their widths extend in a vertical direction, substantially perpendicular to the shelf  17 . The stabilizing beams  38   a,    38   b  are, however, angled relative to one another so that the gap between the stabilizing beams  38   a,    38   b  tapers toward the lower end of the stabilizing beams  38   a,    38   b.  The stabilizing beams  38   a,    38   b  thus define a first slot  39   a  having a vertical extent (length). The first slot  39   a  comprises an inlet at an upper end and an outlet at a lower end. The inlet has a greater width than the outlet and a convergent throat is disposed between the inlet and the outlet. The stabilizing beams  38   a,    38   b  may taper at an angle of greater than 0° and less than 20° to the vertical. The angle may, however, differ between the two stabilizing beams  38   a,    38   b  within a single flow stabilizing device  28 . In particular, as shown, the outermost stabilizing beam  38   a  may be arranged vertically and the innermost stabilizing beam  38   b  angled relative to the outermost stabilizing beam  38   a.    
         [0035]    The outermost stabilizing beam  38   a  may be provided with a product information strip which can be used to display information regarding the products on the shelf portion  30  if the product information strip  34  of the shelf  17  itself is obscured by the stabilizing beams  38   a,    38   b . Alternatively, the stabilizing beams  38   a,    38   b  may be transparent to allow the product information strip  34  of the shelf  17  to be viewed. This may also prevent the stabilizing beams  38   a,    38   b  from blocking light from a light source within the ORDC  2  and thus ensure proper illumination of the products within the ORDC. 
         [0036]    As shown in  FIG. 3 , each of the shelves  17  is provided with a flow stabilizing device  28 . The stabilizing beams  38   a,    38   b  of each shelf  17  are spaced from the shelf  17  so as to form a second slot  39   b  between the innermost stabilizing beam  38   b  and the shelf  17 . The stabilizing beams  38   a,    38   b  are positioned such that the majority of the air curtain  26  passes between the stabilizing beams  38   a,    38   b,  through the first slot  39   a.  A portion of the air curtain  26  may pass between the innermost stabilizing beam  38   b  and the shelf  17 , through the second slot  39   b,  or beyond the exterior surface of the outermost stabilizing beam  38   a.  As described previously, the back panel  12  is perforated to allow air to pass from the duct  16  into the display area  15  where it cools items located on the shelves  17  and on the lower panel  10 . The direction of air flow from the back panel  12  is thus predominantly perpendicular to that of the air curtain  26 . The air from the back panel  12  is entrained with the portion of the air curtain  26  passing through the second slot  39   a  which turns the air flow towards the direction of the air curtain  26 . This reduces the effect the air flow from the back panel  12  has on the air curtain  26 . 
         [0037]    As described previously, the air curtain  26  may be angled away from vertical and the stabilizing beams  38   a,    38   b  may be spaced progressively further from the shelf  17  (or, where the shelves are of different lengths, from the back panel  12 ) from the uppermost shelf  17  to the lowermost shelf  17  so as to be aligned with the air curtain  26 . The spacing between the stabilizing beams  38   a,    38   b  may increase from the uppermost flow stabilizing device  28  to the lowermost flow stabilizing device  28  to account for the air curtain  26  becoming thicker as it passes down the front of the ORDC  2 . 
         [0038]    As described previously, the intake grille  18  is not directly aligned with the discharge grille  20 . To counteract this, the stabilizing beams  38   a,    38   b  of the uppermost flow stabilizing device  28  are curved so that the air curtain  26  is turned slightly as it passes through this flow stabilizing device  28 . As shown, the stabilizing beams  38   a,    38   b  of the uppermost flow stabilizing device  28  may also run parallel to one another such that they do not converge. 
         [0039]      FIGS. 4 and 5  provide a comparison of the flow characteristics of the air curtain  26  without the flow stabilizing devices  28  of the invention ( FIG. 4 ) and with the flow stabilizing devices  28  ( FIG. 5 ). 
         [0040]    As shown in  FIG. 4 , the air leaves the discharge grille  20  as a coherent jet  40 . However, without the flow stabilizing devices  28 , the jet  40  soon becomes unstable in region  42 , and begins to separate. This causes a high level of turbulent mixing in region  44  which warms the air curtain  26  considerably, thus warming the ORDC  2 . 
         [0041]    As shown in  FIG. 5 , with the flow stabilizing devices  28  attached to the shelves  17 , the air again exits the discharge grille  20 , but before the air curtain  26  can become unstable the flow stabilizing device  28  acts to re-stabilize the flow. As described previously, the stabilizing beams  38   a,    38   b  converge such that, as a result of the Venturi effect, the air is accelerated as it passes through the first slot  39   a  of the flow stabilizing device  28 . The acceleration acts to further stabilize the air curtain  26 . The width of the air curtain  26  is also reduced which helps maintain a thin shear layer throughout the length of the air curtain  26 . The second slot  39   b  formed between the innermost stabilizing beam  38   b  and the shelf  17  further promotes stabilization of the air curtain  26  by drawing air from the back panel  12  into the air curtain  26 . 
         [0042]    The shelves  17  may be configured so as to allow the shelf portion  30  to be positioned at different angles. This may be beneficial for displaying different types of products. To allow for this, each flow stabilizing device  28  may be pivotably connected to the shelf  17  so that the flow stabilizing device  28  remains horizontal (or at some other predetermined orientation). For example, the arms  36   a,    36   b  may be pivotably connected to the shelf  17 . Alternatively, the arms  36   a,    36   b  may each comprise first and second members connected to one another at an articulated joint. The arms  36   a,    36   b  may also allow the distance of the stabilizing beams  38   a,    38   b  from the shelf  17  to be varied. In particular, as the shelf  17  is angled away from horizontal, its horizontal extent will reduce so that the stabilizing beams  38   a,    38   b  are located closer to the back panel  12 . The arms  36   a,    36   b  may therefore allow for this to be counteracted so that the stabilizing beams  38   a,    38   b  remain in the correct position for the air curtain  26 . For example, the arms  36   a,    36   b  may allow the stabilizing beams  38   a,    38   b  to be located in a plurality of positions (e.g. defined by discrete mounting holes or a continuous slot) or the arms  36   a,    36   b  themselves may be connected to the shelf  17  in a plurality of positions. Alternatively, the arms  38   a,    38   b  may comprise a telescoping arrangement to alter their length. 
         [0043]    An initial study using Computational Fluid Dynamics has shown that the flow stabilizing device  28  of the invention could provide a reduction of around 40% in convective heat losses. 
         [0044]    Although not shown, the flow stabilizing device  28  may comprise an injector port which receives additional air. For example, the injector port may be connected to the duct  16  via a conduit or the injector port may receive air which passes through the perforated back panel  12 . The injector port may be located adjacent the inlet of the flow stabilizing device  28 . The Venturi effect creates an area of low pressure within the flow stabilizing device  28  as the air curtain  26  is accelerated. This acts to draw in the additional air from the injector port which further increases the velocity of the air curtain, thus helping it to remain stable and intact in extreme ambient conditions. 
         [0045]    The flow stabilizing devices  28  can be connected to a standard shelf  17  and thus allow the flow stabilizing devices  28  to be retrofit to existing ORDCs. The flow stabilizing devices  28  may, however, be integrally formed with the shelves  17  or the ORDC  2 . In this respect, “integral” is intended to convey that the flow stabilizing devices  28  are located within the perimeter of the shelves  17 , rather than being affixed thereto. Nevertheless, the flow stabilizing devices  28  may still be removable from the remainder of the shelf  17  to aid manufacturing and cleaning, for example. 
         [0046]    Although each shelf  17  of the ORDC  2  has been described as having a flow stabilizing device  28 , this need not be the case and only some of the shelves  17  may be provided with flow stabilizing devices  28 . It is, however, desirable that the flow stabilizing devices  28  are provided at regular spacings of between 120 mm and 190 mm, which corresponds to approximately 4 to 6 times the width of the discharge grille  20 , and preferably at spacings of around 160 mm (5 times the width of the discharge grille  20 ). 
         [0047]    Although the flow stabilizing devices  28  have been described as being connected directly to the shelves  17 , they may instead be connected to other parts of the ORDC  2 . For example, the arms  36   a,    36   b  of the flow stabilizing devices  28  may connect to the back panel  12  such that the flow stabilizing devices  28  are positioned between adjacent shelves  17  (or between the lowermost shelf  17  and the lower panel  10 ). In particular, the flow stabilizing devices  28  may be positioned just below each of the shelves  17 . Alternatively, the flow stabilizing devices  28  may be connected to the left and right side walls of the ORDC  2 . In this case, the arms  36   a,    36   b  can be omitted and the stabilizing beams  38   a,    38   b  connected directly to the ORDC  2 . 
         [0048]    The stabilizing beams  38   a,    38   b  also need not lie in the plane of the shelf  17 . For example, the stabilizing beams  38   a,    38   b  may be offset from the shelf  17  such that they are not aligned with the product information strip  34 , thus allowing the product information strip  34  to be viewed. This may be achieved by using arms which are stepped or otherwise configured so that the connection to the shelf  17  and the connection to the stabilizing beams  38   a,    38   b  are offset from one another. 
         [0049]    In certain embodiments, the stabilizing beams  38   a,    38   b  may not converge and are instead arranged parallel to one another. Such parallel stabilizing beams  38   a,    38   b  may guide the air flow and prevent expansion of the air curtain, thus still re-stabilizing the flow. 
         [0050]      FIG. 6  shows a shelf  117  having a flow stabilizing device  128  according to another embodiment of the invention. As shown, the shelf  117  comprises a shelf portion  130  on which products may be displayed. The flow stabilizing device  128  is integrated into the shelf  117  to form a single component. The flow stabilizing device  128  forms a zone of the shelf  117  at or toward an outermost edge of the shelf  117  (i.e. furthest from the back panel  12  of the ORDC  2 ). The flow stabilizing device  128  comprises a honeycomb panel which is embedded within the shelf  117 . The honeycomb panel forms a matrix of open hexagonal cells extending in the direction of the air curtain  26 . Each cell forms a stabilizing channel through which air from the air curtain  26  (and optionally from the back panel  12 ) can pass. The honeycomb panel is positioned to receive the entire air curtain  26 . The stabilizing channels have a uniform cross-section along their length such that the longitudinal axes of the sides extend parallel to one another. However, the stabilizing channels of adjacent flow stabilizing devices  128  may be angled relative to one another to redirect the air curtain. 
         [0051]    As shown in  FIG. 7 , the flow stabilizing device  128  is substantially coplanar with the shelf  117 . Specifically, an upper surface of the flow stabilizing device  128  (i.e. of the hexagonal cells) is substantially coplanar with an upper surface of the shelf portion  130 . A lower surface of the flow stabilizing device  128  (i.e. of the hexagonal cells) may also be substantially coplanar with a lower surface of the shelf portion  130  such that the flow stabilizing device lies within the vertical bounds of the upper and lower surfaces of the shelf portion  130 . The flow stabilizing device  128  thus forms an integral part of the shelf portion  130  which does not obstruct the view of and access to products located on the shelf portion  130 , or on adjacent shelves  117 . 
         [0052]    As shown in  FIG. 7 , in use, the flow stabilizing device  128  acts to re-stabilize the flow of the air curtain  26  after it exits the discharge grille  20  before it can become unstable. Specifically, the stabilizing channels guide the air flow and prevent expansion of the air curtain  26  as it passes down the front of the ORDC  2 . They may also redirect air from the back panel  12  toward the direction of the air curtain  26 . 
         [0053]    In other embodiments, the flow stabilizing device  128  may be a separate component which is attached to an existing shelf. This may allow the flow stabilizing device  128  to be angled relative to the shelf portion  130 , particularly when the shelf  117  itself is inclined. In this manner, the flow stabilizing device  128  may also be offset from the shelf  117 . However, even where the flow stabilizing device  128  is provided within the body of the shelf (as shown in  FIG. 6 ), it may still be possible to angle the flow stabilizing device relative to the shelf portion  130 . For example, the flow stabilizing device  128  may be pivotably mounted via a gimbal joint. With this arrangement, it may be desirable for the upper surface of the flow stabilizing device  128  to remain at or below the level of the upper surface of the shelf  117  at each angular position. It may also be possible to adjust the fore and aft position of the flow stabilizing device  128  within the body of the shelf. For example, the flow stabilizing device  128  may be mounted on rails to allow it to be moved. The flow stabilizing device  128  may be moved along the rails so as to receive the entire curtain. Cover plates may be provided to between the flow stabilizing device and the shelf  117  to maximize the usable area of the shelf portion  130 . 
         [0054]    Although the flow stabilizing device  128  has been described as being formed by a honeycomb panel, it will be appreciated that other cellular structures may be used with form a matrix of flow stabilizing channels. 
         [0055]    Although the upper surface of the flow stabilizing device  128  has been described as being substantially coplanar with the upper surface of the shelf portion  130 , it may also lie below the level of the upper surface of the shelf portion  130 . It is, however, useful for the upper surfaces to be substantially coplanar so as to form a continuous surface. This may aid removing items from the shelf, particularly where they are heavy and the customer wishes to slide the item across the surface of the shelf. On the other hand, the lower surface of the flow stabilizing device  128  may terminate above or project below the lower surface of the shelf portion  130 . However, it is desirable, particularly where the shelves are close together relative to the height of goods on the shelf portions  130 , that the lower surface of the flow stabilizing device  128  terminates at or above the level of the shelf portion  130  so as not to obstruct the view of and access to the shelf  117  below. 
         [0056]    The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention. 
         [0057]    To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or embodiments of the invention. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or embodiment of the invention may also be used with any other aspect or embodiment of the invention.