An extraction apparatus and method

Abstract

An extraction apparatus for an open refrigerated display case (ORDC) 2 and an associated method, the extraction apparatus comprising an extraction unit 36 located on an upper wall 8 of the ORDC and an

Description

The present disclosure relates to an extraction apparatus and method. In particular, the extraction apparatus and method may be used to extract cold air from an aisle of a supermarket or the like. BACKGROUND 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, some of the cold air from the air curtain inevitably spills out of the ORDC and into the aisle, creating a region of cold air adjacent to the floor (referred to as cold-aisle syndrome) which can be unpleasant for shoppers. To counter this cold-aisle syndrome, supermarkets may provide heating through HVAC systems. However, this increases energy consumption of both the HVAC systems and also the ORDCs. It is therefore desirable to address or alleviate these issues. SUMMARY OF THE INVENTION In accordance with a first aspect, there is provided a system comprising an extraction apparatus and an open refrigerated display case, the extraction apparatus comprising: 5 an extraction unit received on an upper wall of the open refrigerated display case to form an extraction plenum between a back wall of the open refrigerated display case and an adjacent wall; wherein the extraction unit comprises a fan having an inlet fluidically coupled to the extraction plenum and an outlet; 10 wherein the fan is configured to generate negative pressure in the extraction plenum so as to draw cold air from in front of the ORDC into the extraction plenum through a base portion of the ORDC and to emit a jet of air from the outlet of the fan; wherein the outlet is directed along the upper wall of the open refrigerated display case such that the jet of air is emitted from the outlet of the fan along the upper wall; 15 and wherein the jet of air is exposed to ambient air as it passes along the upper wall such that the ambient air is entrained with the cold air. The fan may be a cross-flow fan. 20 The extraction apparatus may further comprise a heater which heats the cold air drawn into the extraction plenum. The heater may be a heating element which is located adjacent the outlet of the fan. 25 The heater may be a heat pump. The adjacent wall may be a back wall of an adjacent open refrigerated display case provided in a back-to-back arrangement. 30 The adjacent wall may be a building wall. The extraction apparatus may further comprise a guide component which is attached along the upper wall of the open refrigerated display case. 35 The guide component may comprise a Coanda surface which redirects the jet of air as it passes over a front end of the upper wall. The extraction apparatus may further comprise an air filtration and / or sterilisation unit. 5 In accordance with another aspect, there is provided an ORDC comprising an extraction apparatus as described. In accordance with another aspect, there is provided a method of extracting cold air 10 from in front of an open refrigerated display case, the method comprising: attaching an extraction unit of an extraction apparatus to an upper wall of the open refrigerated display case to form an extraction plenum between a back wall of the open refrigerated display case and an adjacent wall, wherein the extraction unit comprises a fan having an inlet fluidically coupled to the extraction plenum and an 15 outlet; operating the fan of the extraction unit to generate negative pressure in the extraction plenum so as to draw the cold air from in front of the ORDC into the extraction plenum through a base portion of the ORDC and to emit a jet of air from the outlet of the fan; 20 wherein the outlet is directed along the upper wall of the open refrigerated display case such that the jet of air is emitted from the outlet of the fan along the upper wall; and wherein the jet of air is exposed to ambient air as it passes along the upper wall such that the ambient air is entrained with the cold air. 25 The method may further comprise heating the cold air drawn into the extraction plenum. The method may further comprise attaching a guide component to the upper wall of the 30 open refrigerated display case. The method may further comprise filtering and / or sterilising the cold air drawn into the extraction plenum. BRIEF DESCRIPTION OF DRAWINGS 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 side cross-sectional view of an ORDC showing air flow; Figure 2 is a side cross-sectional view of the ORDC according to an embodiment of the disclosure; with an extraction apparatus Figure 3 is a side cross-sectional view of the ORDC according to another embodiment of the disclosure; with an extraction apparatus Figure 4 is a side cross-sectional view of the ORDC according to another embodiment of the disclosure; and with an extraction apparatus Figure 5 is a side cross-sectional view of the ORDC according to another embodiment of the disclosure. with an extraction apparatus DETAILED DESCRIPTION Figure 1 shows an 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. 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) on which items may be displayed. The shelves 17 are affixed to the back panel 12. 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 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 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. 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 Figure 1, 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 cold air which spills out of the ORDC 2 creates a region of cold air (relative to ambient air or a desired air temperature) adjacent to the floor which can be unpleasant for shoppers. As shown in Figure 2, the ORDC 2 may be modified by installing an extraction apparatus. As shown, the ORDC 2 may be located with the back wall 6 spaced from a building wall 34 (which may be an external wall or a partition wall, for example). A pair of cover plates extend from the left and right side-walls to the wall 34 and an extraction unit 36 is located on the upper wall 8 and extends between the ORDC 2 and the wall 34. The cover plates, back wall 6, building wall 34 and the extraction unit 36 therefore define a closed space which forms an extraction plenum 38. The extraction unit 36 comprises a fan 40. In this example, the fan 40 is a cross-flow (i.e., transverse / tangential) fan. The fan 40 has a housing which defines an inlet 42 that is directed towards and fluidically coupled to the extraction plenum 38 and an outlet 44 that is directed along the upper wall 8. An impeller 46 is mounted within the housing. The impeller 46 extends across the width of the ORDC 2 between the left and right-side walls (although not necessarily along the full width of the ORDC 2). The impeller 46 is rotatably mounted about an axis which extends across the width of the ORDC 2 and is driven by a motor. Rotation of impeller 46 draws air from the extraction plenum 38 into the inlet 42 of the fan 40 and forces this towards and out of the outlet 44. The fan 40 therefore creates a negative pressure in the extraction plenum 38. The negative pressure draws the cold air which has gathered adjacent to the floor and in front of the ORDC 2 through a base portion of the ORDC 2. The base portion is provided with vented panels 30, 32 which allows air to pass through the base portion and into the extraction plenum 38. In other examples, the rear of the base portion may be left open instead of including a vented panel. The cold air is forced out of the outlet 44 and along the upper wall 8. A shear layer is formed between the jet of air emitted from the outlet 44 and the static ambient air. Consequently, vortices are generated along the shear layer which cause the ambient air to be entrained with the cold air, thereby increasing the temperature of the jet of air as it passes along the upper wall 8. As shown in Figure 2, a guide component 48 may be attached to the upper wall 8 adjacent the front of the ORDC 2. The guide component 48 is designed to cover any abrupt edges along the upper wall and to provide a smoothly curved upper (Coanda) surface 50. The jet of air comes into contact with the upper surface 50 and adheres to the upper surface 50 as a result of the Coanda effect. The upper surface 50 thus redirects the jet of air towards a desired trajectory. In other examples, the guide component 48 may extend to the outlet 44 of the fan 40. The guide component 48 may be connected to the fan 40 to form an integrated unit which is placed on top of the upper wall 8. By moving the cold air from adjacent to the floor to an elevated height (e.g., at the height of the upper wall 8), the effect of the cold air on shoppers is minimised. In particular, as described above, the cold air is effectively heated by virtue of mixing with ambient air and so is less unpleasant for shoppers when it is emitted from the extraction apparatus. Moreover, by extracting the cold air from adjacent the floor, the temperature of the floor is increased which therefore reduces the heat drawn away from shoppers by the floor itself. Figure 3 shows an alternative arrangement in which the fan 40 is provided with a heating element 52. The heating element 52 is located adjacent to the outlet 44 of the fan 40. When activated, the heating element 52 heats the jet of air emitted by the fan 40 in order to allow the temperature to be controlled. In this way, the arrangement of the present invention may obviate the need for conventional air conditioning systems, such as ceiling mounted cassette units. It will be appreciated that heating may be provided in other manners. For example, Figure 4 shows a further alternative which utilises a heat pump 54 to heat the air before it passes through the fan 40. The heat pump 54 comprises a condenser 56 located within or adjacent to the extraction plenum 38, an evaporator 58 situated outside of the building, a compressor 60 and an expansion valve 62. The heat pump 54 transfers heat from outside of the building into the extraction plenum 38 in order to heat the air passing therethrough. It may also be possible to reverse the heat pump 54 in order to further cool the air in the extraction plenum 38 where cooling is desired. Figure 5 shows a further example in which a filtration and / or sterilisation unit 64 is provided. In this example, the filtration and / or sterilisation unit 64 is provided in the base portion of the ORDC 2, but in other examples it may be located anywhere along the fluid pathway, such as at the inlet or outlet of the fan 40 or within the extraction plenum 38. Although the fan 40 has been described with reference to a cross-flow fan, it will be appreciated that other types of fan may be used to create a negative pressure in the extraction plenum 38. In other examples, a first ORDC and a second ORDC may be disposed in a back-to-back arrangement, rather than against a building wall. In such an arrangement, the extraction plenum 38 may be formed between the back walls 6 of the ORDCs. A pair of extraction units 36 may be used and placed in a back-to-back arrangement in order to achieve the same effect as described above, with each directing a jet of air over the upper wall of its respective ORDC. Alternatively, a single extraction unit 36 may be used to draw cold air from the adjacent aisles but to direct a jet of air over the upper wall of only one of the ORDCs. In other examples, a plurality of ORDCs located side-by-side may form a common extraction plenum 38 which is served by a single extraction unit 36. The vented panels 30, 32 may already be present in a conventional ORDC in order to provide ventilation. However, where the ORDC does not include a fluid pathway through the base portion, the panels of the base portion may be modified or replaced in order to allow this. In other examples, the base portion of the ORDC 2 may comprise an air retrieval duct specifically intended to receive the cold air from adjacent the floor. For example, the air retrieval duct may be provided as a separate component on which the ORDC sits. Although the outlet 44 (and the jet of air from it) has been described as being directed along the upper wall 8, it will be appreciated that in other examples, the outlet may be oriented in other directions. For example, the outlet 44 may be angled upwards away from the upper wall 8. In particular, the outlet 44 may be directed vertically upwards towards a ceiling. In other examples, the outlet 44 may be spaced upwards from the level of the upper wall 8. With such an arrangement, the outlet 44 may be oriented in a direction which is parallel to, but spaced upwards, from the upper wall 8. In other examples, where the outlet 44 is spaced upwards from the level of the upper wall 8, the outlet 44 may be angled downwards towards the upper wall 8 or upwards away from the upper wall 8. The outlet 44 of the fan 40 may be provided with a replaceable or reconfigurable nozzle component which allows the direction of the jet of air to be modified based on the location of the ORDC. 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. The invention is not limited to the embodiments described herein, and may be modified 5 or adapted without departing from the scope of the present invention as defined by the claims.

Claims

1. A system comprising an extraction apparatus and an open refrigerated display case, the extraction apparatus comprising:5 an extraction unit received on an upper wall of the open refrigerated display case to form an extraction plenum between a back wall of the open refrigerated display case and an adjacent wall;wherein the extraction unit comprises a fan having an inlet fluidically coupled to the extraction plenum and an outlet;10 wherein the fan is configured to generate negative pressure in the extraction plenum so as to draw cold air from in front of the ORDC into the extraction plenum through a base portion of the ORDC and to emit a jet of air from the outlet of the fan;wherein the outlet is directed along the upper wall of the open refrigerated display case such that the jet of air is emitted from the outlet of the fan along the upper wall;15 andwherein the jet of air is exposed to ambient air as it passes along the upper wall such that the ambient air is entrained with the cold air.

2. A system as claimed in claim 1, wherein the fan is a cross-flow fan.

203. A system as claimed in claim 1 or 2, further comprising a heater which heats the cold air drawn into the extraction plenum.

4. A system as claimed in claim 3, wherein the heater is a heating element which is 25 located adjacent the outlet of the fan.

5. A system as claimed in claim 3, wherein the heater is a heat pump.

6. A system as claimed in any one of the preceding claims, further comprising a30 guide component which is attached along the upper wall of the open refrigerateddisplay case.

7. A system as claimed in claim 6, wherein the guide component comprises a Coanda surface which redirects the jet of air as it passes over a front end of the upper 35 wall.17 07 258. A system as claimed in any one of the preceding claims, further comprising an air filtration and / or sterilisation unit.

9. A method of extracting cold air from in front of an open refrigerated display case,5 the method comprising:attaching an extraction unit of an extraction apparatus to an upper wall of the open refrigerated display case to form an extraction plenum between a back wall of the open refrigerated display case and an adjacent wall, wherein the extraction unit comprises a fan having an inlet fluidically coupled to the extraction plenum and an10 outlet directed along the upper wall of the open refrigerated display case;operating the fan of the extraction unit to generate negative pressure in the extraction plenum so as to draw the cold air from in front of the ORDC into the extraction plenum through a base portion of the ORDC and to emit a jet of air from the outlet of the fan;15 wherein the outlet is directed along the upper wall of the open refrigerated display case such that the jet of air is emitted from the outlet of the fan along the upper wall;andwherein the jet of air is exposed to ambient air as it passes along the upper wall such that the ambient air is entrained with the cold air.2010. A method as claimed in claim 9, further comprising heating the cold air drawn into the extraction plenum.

11. A method as claimed in claim 9 or 10, further comprising attaching a guide25 component to the upper wall of the open refrigerated display case.

12. A method as claimed in any one of claims 9 to 11, further comprising filtering and / or sterilising the cold air drawn into the extraction plenum.

Images