GB2549719A

GB2549719A - An open refrigerated display case

Info

Publication number: GB2549719A
Application number: GB1607163.1A
Authority: GB
Inventors: John Peter Wirth Nicholas
Original assignee: Wirth Research Ltd
Current assignee: Wirth Research Ltd
Priority date: 2016-04-25
Filing date: 2016-04-25
Publication date: 2017-11-01
Anticipated expiration: 2036-04-25
Also published as: GB2549719B

Abstract

An open refrigerated display case 2 comprising: a refrigerated display area 15; an air outlet 20 and an air inlet 18 opening into the display area 15; a plenum 16 linking the air inlet 18 to the air outlet 20 which directs air flow to form an air curtain across 36 the display area 15; an air retrieval duct 28 connectable to a suction source with a retrieval inlet 29 which extends across the width of the display case 2 and is positioned below the air inlet 18; and a Coanda surface 34 positioned above the retrieval inlet 29 which extends forward of the retrieval inlet 29 at its upper end and curves back towards the retrieval inlet 29 at its lower end such that split out air from the air curtain 36 is drawn towards the retrieval inlet 29. The air retrieval duct may curve upwards at the inlet to form an upwards angle.

Description

AN OPEN REFRIGERATED DISPLAY CASE

The invention relates to an open refrigerated display case.

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.

It is therefore common for supermarkets to use open-fronted display cases (Open Refrigerated Display Cases; herein “ORDCs”). ORDCs utilise 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.

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. Further, a portion of the air curtain typically spills out of the ORDC into the aisle, leading to the so-called “cold-aisle syndrome”. This not only leads to discomfort for customers, but also increases the energy consumption of the ORDC itself and also HVAC systems used in the building.

The invention seeks to provide an ORDC which addresses at least some of the issues described above.

According to an aspect of the invention there is provided an open refrigerated display case comprising: a refrigerated display area; an air outlet and an air inlet opening into the display area and spaced from one another; a plenum fluidically coupling the air inlet to the air outlet, the plenum 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; an air retrieval duct connectable to a suction source, the air retrieval duct having a retrieval inlet, the retrieval inlet extending across the width of the open refrigerated display case and being positioned below the level of the air inlet; and a Coanda surface positioned above the retrieval inlet, the Coanda surface extending forward of the retrieval inlet at its upper end and curving back towards the retrieval inlet at its lower end such that air from the air curtain which is spilt out of the display area is drawn towards the retrieval inlet of the air retrieval duct.

The air retrieval duct may be formed by upper and lower surfaces which are spaced from one another.

The upper surface may extend beyond the lower surface to form the Coanda surface.

The lower surface may curve upwards over a portion extending towards the retrieval inlet. A portion of the air retrieval duct extending towards the retrieval inlet may be angled upwards. This portion of the air retrieval duct may be curved along its length.

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:-

Figure 1 is a perspective view of an open refrigerated display case (ORDC) according to an embodiment of the invention;

Figures 2 and 3 are side cross-sectional views of the ORDC of Figure 1 showing air flow and temperature contour lines respectively; and

Figures 4 and 5 are side cross-sectional views of a conventional ORDC showing air flow and temperature contour lines respectively, for comparison.

Figures 1 to 3 show an ORDC 2 according to an embodiment of the invention. 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 5, 7. A lower panel 10, a back panel 12 and an upper panel 14 are disposed within the cabinet portion.

The lower, back and upper panels 10, 12, 14 form a display area 15 which is provided with a plurality of shelves 17 (five levels of shelves are shown, each comprising two separate sections) on which items may be displayed. The shelves 17 are affixed to the back panel 12.

As shown in Figures 2 and 3, 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 plenum 16. An intake grille 18 is provided at the lower panel 10 to form an inlet to the plenum 16. Similarly, a discharge grille 20 is provided at the upper panel 14 to form an outlet from the plenum 16. The intake grille 18 and the discharge grille 20 are thus fluidically coupled to one another by the plenum 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. A fan 22 and a heat exchanger 24 are located within the plenum 16 adjacent to the intake grille 18 and thus are disposed between the lower wall 4 and the lower panel 10. A guide strip 26 runs along the front of the ORDC 2 at the bottom of the display area 15. The guide strip 26 projects upwards from the lower panel 10 at a position which is in front of (i.e. external to) the intake grille 18. A base portion of the ORDC 2 comprises an air retrieval duct 28 which has an inlet 29 that runs along the width of the ORDC 2 between the left and right side walls 5, 7 (although not necessarily along the full width of the ORDC 2). The air retrieval duct 28 is formed by an upper surface 30 and a lower surface 32 which run parallel to one another both across the width of the ORDC 2 and also from front to back. The air retrieval duct 28 therefore has a rectangular cross-section which is constant along its length. The upper surface 30 extends beyond the inlet 29 to the air retrieval duct 28 (i.e. beyond the lower surface 32) and forms a Coanda surface 34. At its upper end, the Coanda surface 34 projects forward of the intake grille 18 and the guide strip 26. The Coanda surface 34 follows a continuous (although not necessarily constant) curve from the upper end to the inlet 29 of the air retrieval duct 28. A portion of the air retrieval duct 28 adjacent the inlet 29 is also curved and transitions the orientation of the air retrieval duct 28 to horizontal (although it may instead be angled away from horizontal i.e. upwards or downwards). The lower surface 32 therefore forms a lip which curves upwards (from back to front) at the inlet portion and the inlet 29 of the air retrieval duct 28 is angled upwards. The upper surface 30 curves smoothly over the Coanda surface 34 from an orientation which is towards vertical (i.e. closer to vertical than horizontal) to an orientation which is towards horizontal (i.e. closer to horizontal than vertical).

Although not shown, the air retrieval duct 28 is connected to a suction source (i.e. a pump) which creates a negative pressure within the air retrieval duct 28. The suction source may be located within the air retrieval duct 28 or may be external to the ORDC 2. The air retrieval duct 28 may extend vertically up the rear of the ORDC 2 within or external to the back wall 6, for example.

In use, the fan 22 draws air into the plenum 16 via the intake grille 18 which then passes through the heat exchanger 24 where it is cooled to well below the ambient temperature.

After passing through the heat exchanger 24, the air continues through the plenum 16 between the back wall 6 and the back panel 12. The back panel 12 may be perforated allowing air to pass from the plenum 16 into the display area 15 where it cools items located on the shelves 17 and on the lower panel 10.

The remaining air flows through the plenum 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 36. The air curtain 36 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 plenum 16. The air curtain 36 thus forms a non-physical barrier which separates the display area 15 from the ambient air surrounding the ORDC 2.

As shown in Figures 2 and 3, the air curtain 36 may spread as it passes over the front of the ORDC 2 such that a portion of the air curtain 36 spills out of the front of the ORDC 2 and thus over an external surface of the guide strip 26. The spilt air comes into contact with the Coanda surface 34 and adheres to the Coanda surface 34 as a result of the Coanda effect. The Coanda surface 34 thus reorients the air flow from the substantially vertical flow of the air curtain 36 and draws the air towards the inlet 29 of the air retrieval duct 28. The angle of the Coanda surface 34 from vertical at its upper end may be selected so as to ensure that the air adheres to the surface. The negative pressure generated in the air retrieval duct 28 by the suction source subsequently draws the air into and along the air retrieval duct 28.

The spilt air may be recycled to another area where the cool air can be usefully used or simply discharged. For example, the air retrieval duct 28 may be connected to an extraction system of the store which discharges the cool air to the atmosphere. Alternatively, the air retrieval duct 28 may transfer the cool air to another area of the store which requires cooling, either directly or via a HVAC system. The air retrieval duct 28 may also transfer the cool air to components which require cooling. Such components may be integral to the ORDC 2 or part of other systems or devices. The cool air may also be recycled into the main plenum 16 so that it again forms part of the air curtain 26 (possibly after additional cooling). The suction source may therefore be provided by the fan 22.

As the air is initially drawn towards the air retrieval duct 28 using the Coanda effect, the suction required to draw the air into the air retrieval duct 28 may be reduced. Further, this arrangement minimises mixing with ambient air, thus ensuring that the air retrieval duct 28 extracts predominantly air spilt from the ORDC 2.

As shown in Figures 4 and 5, in a conventional ORDC, the air which spills out of the front of the ORDC flows down to the ground and then flows away from the ORDC along the aisle of the store. This leads to cold-aisle syndrome.

Although the air retrieval duct 28 has been described as having a rectangular cross-section formed by parallel upper and lower surfaces, other arrangements may be used. In particular, the air retrieval duct 28 may be divided into a plurality of separate ducts which may be pill-shaped. The upper and lower surfaces may also diverge away from one another along the length of the air retrieval duct 28 (or part thereof) in the direction of flow.

Although the Coanda surface 34 has been described as following a continuous curvature, the Coanda surface may be interrupted by a bumper which runs along the front of the ORDC 2 to protect it from impacts from shopping trolleys, etc. The bumper may be located at the upper end of the Coanda surface 34 where it projects most from the ORDC 2. Below the level of the bumper, the Coanda surface 34 may, however, still follow a continuous curvature.

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 as defined by the claims.

Claims

1. An open refrigerated display case comprising: a refrigerated display area; an air outlet and an air inlet opening into the display area and spaced from one another; a plenum fluidically coupling the air inlet to the air outlet, the plenum 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; an air retrieval duct connectable to a suction source, the air retrieval duct having a retrieval inlet, the retrieval inlet extending across the width of the open refrigerated display case and being positioned below the level of the air inlet; and a Coanda surface positioned above the retrieval inlet, the Coanda surface extending forward of the retrieval inlet at its upper end and curving back towards the retrieval inlet at its lower end such that air from the air curtain which is spilt out of the display area is drawn towards the retrieval inlet of the air retrieval duct.

2. An open refrigerated display case as claimed in claim 1, wherein the air retrieval duct is formed by upper and lower surfaces which are spaced from one another.

3. An open refrigerated display case as claimed in claim 2, wherein the upper surface extends beyond the lower surface to form the Coanda surface.

4. An open refrigerated display case as claimed in claim 2 or 3, wherein the lower surface curves upwards over a portion extending towards the retrieval inlet.

5. An open refrigerated display case as claimed in any preceding claim, wherein a portion of the air retrieval duct extending towards the retrieval inlet is angled upwards.

6. An open refrigerated display case as claimed in claim 5, wherein said portion of the air retrieval duct is curved along its length.

7. An open refrigerated display case substantially as described herein with reference to and as shown in Figures 1 to 3.