CN1753634A - Refrigerated display merchandiser with improved air curtain - Google Patents

Abstract

A refrigerated merchandiser includes a display case defining a product display region having an open-front isolated from the ambient air of the store by means of a downwardly directed inner air curtain of relatively cold refrigerated air and a downwardly directed outer air curtain of relatively warmer air. The inner air curtain discharges through a first air outlet (34) at a first discharge velocity and the outer air curtain discharges through a second air outlet (70) at a second discharge velocity, the second discharge velocity being at least about 1.4 times greater than the first discharge velocity, and most advantageously, from about 1.4 to about 1.8 times greater than the first discharge velocity.

Description

Refrigerated display merchandiser with improved air curtain

This application is also a continuation-in-part of related co-pending application Serial No. 10/374,640, filed February 26,2003.

technical field

In general, the present invention relates to refrigerated display cases for use in supermarkets, minimarts, convenience stores, and other commercial establishments for displaying and selling refrigerated or frozen items for sale. More particularly, the present invention relates to front opening refrigerated display cases in which a curtain of cold air passes downwardly over the front opening article display area of the merchandise case.

Background technique

Refrigerated display merchandise cases with front-opening display areas, also commonly referred to as display cases, are commonly used in supermarkets, mini-marts, convenience stores, and other commercial establishments for the display and sale of refrigerated or frozen items for sale. The front-opening feature of the display case allows consumers to easily reach the item display area for picking and moving purchased items without the inconvenience of needing to open the cabinet door to access the items. Typically, a curtain of cold air passes downward at a relatively high velocity over the front opening of the display case, creating an invisible dividing line between the item display area and the store area in front of the display case. Air curtains not only help to keep cold air in the item display area of the display case and thereby cool the displayed items on the display case shelves, but also serve to isolate the item display area from the ambient air in the store to a certain extent role. Ambient air that does enter the open merchandise display area increases the cooling demand of the refrigeration system associated with the display case, causing an undesired increase in energy consumption. Furthermore, such ambient air may also cause a localized temperature increase within the item display area sufficient to cause an undesired increase in item temperature, which may adversely affect item quality.

A problem encountered when the cooling air curtain passes downwardly through the front opening of the item display area of the display case is that ambient air is entrained into the cooling air flow forming the air curtain. Turbulence can exist at the interface between the relatively high velocity air curtain air and the normally stationary ambient air located in front of the display case. Due to this turbulence, some ambient air is undesirably entrained into the air curtain. In the prior art, multiple air curtain showcases have been developed to deal with this entrainment problem. For example, display cases with two adjacent juxtaposed but independently occurring cooling air curtains are common in the art. Typically, as disclosed by Maehara in US Patent 4,633,677, the outermost air curtains are slightly warmer than the innermost air curtains in order to protect the cooler innermost air curtains from entrainment of ambient air.

Also, it is well known in the art that a third air curtain of higher temperature ambient air created outside of one or two cool air curtains can be used as a means of reducing entrainment of ambient air from the store into the cool air curtain. Abraham in US Patent 4,267,706 discloses creating an ambient air curtain outside the innermost cool air curtain, the outer ambient air curtain being directly downward parallel and adjacent to the inner cool air curtain. Beckwith et al. in US Patents 3,648,482 and 3,850,003, MacMaster et al. in US Patent 3,827,254, and Roberts in US Patents 5,345,778 and 5,357,767 respectively disclose creating ambient air curtains external to the cooling air curtain. The air curtain in the item display area closest to the showcase is the coldest, while the temperature of the middle air curtain is slightly higher than that of the innermost air curtain, but significantly lower than that of the outermost ambient air curtain. The effect of the warmer middle cool air curtain is to slow down the intrusion of the innermost cooler air curtain by the intrusion of hot air from the outermost ambient air curtain. The direction of the outermost ambient air curtain is basically vertically downward, either parallel to and close to the middle air curtain, or slightly inward towards the middle air curtain, to prevent the cooling from the middle and innermost cold air curtain Air escapes from the item display area of the showcase. The outermost ambient air curtain ideally diffuses itself near the bottom of the store display case without being drawn into the air return inlet through which the cool air curtain returns to the evaporator chamber.

While generally very effective at reducing the amount of ambient air intrusion into the circulating cool air compared to a single air curtain, in the case of refrigerated merchandisers with two or three air curtains, there is still a significant amount of entrainment. It is generally recognized that in such multiple air curtain designs, entrainment is reduced when adjacent air curtains have relatively uniform velocities such that shear instability at the interface between the air curtains is minimized. Thus, in a typical prior art merchandiser, the respective exhaust velocities of the individual air curtains, i.e. the exhaust velocities of the respective air streams as they are expelled from their respective nozzles at the top of the display case, are designed to be substantially equal where they should Two or three air curtains appear. However, as the air curtain flows downward, the outer air curtain tends to spread and escape into the store, reducing the velocity, while the inner air curtain tends to increase the velocity due to the self-extraction effect and the increase of air from the refrigerated display case. Consequently, when the air curtains blow downward, the shear instability at the interface of adjacent air curtains increases, causing increased entrainment of taller, more humid air into the inner cool air curtain. Accordingly, there is a need for an improved air curtain system that can inexpensively address the entrainment of internal air curtains of incoming cool air.

Contents of the invention

The refrigerated merchandiser of the present invention includes a display case defining an article display area having a front opening through an inner air curtain downwardly directed by cooler air and an outer air curtain preferably downwardly directed by warmer air. Separated from the ambient air of the store. According to the present invention, the exhaust velocity of the outer air curtain is kept at least 1.4 times of the exhaust velocity of the inner air curtain, and preferably within the range of about 1.4 to 2.4 times greater than the exhaust velocity of the inner air curtain . In a preferred embodiment, the outer air curtain contains ambient air.

Description of drawings

Figure 1 shows a side view of a preferred embodiment of a refrigerated merchandiser having a front opening display case with a dual air flow air curtain isolating a first environment inside the display case from a second environment outside the display case open; and

Figure 2 is a graphical representation showing the amount of load change required for a cooling system associated with a refrigerated merchandiser as a function of air curtain velocity ratio.

Detailed ways

Referring now to FIG. 1, the refrigerated merchandiser 10 includes an outer cabinet 12 and an inner cabinet liner 20 that defines a front-opening merchandise display area 30 within its boundaries. The outer cabinet has a base 13, a rear wall 14 extending upwards from the rear of the base 13, a top wall 15 extending forward from the rear wall, and a pair of vertically extending from the base 13 to the top wall. 15 and a side wall 16 extending forward from the rear wall 14 . The inner cabinet liner 20 has a top panel 28 , a back panel 26 , a bottom panel 24 and opposing side panels 23 which together define the front-opening item display area 30 . Each of the cabinet base 13, rear wall 14, top wall 15, and side walls 16 are insulated, as in conventional practice, so that the interior of the cabinet 12, including the article display area 30, and the Excess heat transfer is thermally isolated.

Perishable items 80 on sale may be displayed on shelves 18 disposed within the item display area 30 above the upper surface of the floor 24 . The item display area 30 has a front opening 25 so that consumers can not only see but also reach into the product display area 30 to pick and move items 80 they want to buy. Item display area 30 is cooled in a conventional manner to achieve the desired item temperature, typically a temperature between -10°F to less than about 40°F, depending on the items to be sold therein and whether the items are frozen or non-frozen.

The refrigerated merchandiser 10 further includes a refrigerated compartment 40, generally disposed within the display cabinet 12 between the base 13 and the floor 24, as shown in FIG. Coil evaporator 50 and a blower 60, such as one or more fans. However, it should be understood that the particular type of blower employed is not relevant and limiting of the invention. As in conventional practice, the refrigerant passing through the tubes of the evaporator 40 cools the air passing over the surfaces of the evaporator tubes. Refrigerant is usually provided by a remote refrigeration unit located elsewhere in the store. However, it should be understood that the present invention may also be used with stand-alone refrigerated merchandisers, which include their own refrigeration units for supplying refrigerant.

Air circulation ducts 32 are respectively formed between the rear wall 14 and the top wall 15 of the outer cabinet 12 and the back panel 26 and the top panel 28 of the inner window liner 20 . A blower 60 is used to direct air from the air inlet 42 through the chamber 40 to pass through the evaporator 50 and thence through the duct 32 to the first air outlet 34 . As previously stated, the circulating air is already cooled to the desired temperature as it passes through the evaporator 50 . From the first air outlet 34 , the cool air is directed downwards along a first path through the front opening 25 of the item display area back to the air inlet 42 by vanes provided in the first air outlet 34 . Thus, cool air is recycled and continuously circulated through chamber 40 and duct 32 to convert the energy expended in cooling the cool air. In addition, through the aforementioned refrigeration device, a cold air curtain 45 is formed through the front-opening item display area 30 from the top to the bottom thereof. In order to further provide cold air directly directed to the item display area 30 , a plurality of openings 24 may be provided in the back plate 26 , through which part of the cold air circulated through the duct 32 can be directly passed into the item display area 30 . This cool air will also be directed by the blower back into the chamber 40 through the air inlet 42 for circulation.

In front of the top of the cabinet 12 , a second air outlet 70 is provided outside the first air outlet 34 . Compared to existing refrigerated merchandisers, the second air outlet 70 is used to direct warmer air generally downward along a second path outside the first path, followed by cooled air. In this way, a warmer outer air curtain 65 is formed outside of the cooler inner air curtain 45 , ie further away from the item display area 30 . The warmer outer air curtain 65 acts as a buffer between the cooler inner air curtain 45 and the store surroundings. Also, when the outer air curtain 65 reaches the bottom area of the display cabinet 12, it escapes outward into the store rather than entering the air inlet 42 in the bottom front of the cabinet. Thus, entrainment of hot air into the cooler inner air curtain and then into chamber 40 through inlet 42 is minimized, thereby reducing energy consumption in cooling the recirculated cold air.

The first air outlet 34 and the second air outlet 70 are located in the top front area of the showcase 12 , wherein the second air outlet 70 is located outside the first air outlet 34 , ie closer to the front of the showcase 12 . As previously noted, the first air outlet 34 communicates with the duct 32 and directs cooler air driven by the blower 60 downwardly through the front opening of the item display area 30 to form the inner air curtain 45 . The second air outlet 70 channels a warmer air source, such as ambient air from a store, and directs the warmer air driven by its associated second blower 72 downward to form the external air curtain 65 .

The outer air curtain 65 is directed downward at an exhaust velocity that is at least 1.4 times the exhaust velocity of the inner air curtain 45 . The term exhaust velocity refers to the velocity at which the airflow is discharged from the respective air outlets at the top of the showcase 30 . Therefore, the exhaust velocity of the inner air curtain 45 is the velocity of the airflow discharged from the air outlet 34 , and the exhaust velocity of the outer air curtain 65 is the velocity of the airflow discharged from the air outlet 70 . Most advantageously, the exhaust velocity of the outer air curtain 65 is maintained at a level equal to about 1.4 to 2.4 times the exhaust velocity of the inner air curtain 45 .

Referring now to FIG. 2, the vertical axis represents the load reduction factor, which refers to the refrigeration load relative to the dual air curtain load of only the inner air curtain, and the horizontal axis represents the velocity ratio of the outer air curtain to the inner air curtain. Therefore, the lower the load reduction factor, the more effective the double air curtain. As shown in Figure 2, by maintaining the ratio of the exhaust velocity of the outer air curtain to the exhaust velocity of the inner air curtain in the range of about 1.4 to about 1.8, the dual function of the barrier in reducing airflow through the air curtain The efficiency of parallel air curtains is maximized. Keeping the velocity ratios of the air curtains within this range minimizes velocity gradients, and thus shear instabilities between adjacent air curtains longitudinally along the interface between adjacent air curtains, thereby minimizing Less air entrainment from higher velocity air curtains into lower velocity air curtains. Therefore, according to the use of the present invention, through a double air curtain of parallel airflow of the first and second fluids, and maintaining the exhaust velocity of the outer airflow at an exhaust velocity equal to about 1.4 times to about 1.8 times the exhaust velocity of the inner airflow level, can maintain a very effective isolation barrier between the two environments.

The above description is exemplary and not restrictive. From the above description, those skilled in the art can realize many changes and modifications of the present invention, which will also fall within the spirit and scope of the present invention. Preferred embodiments of the invention have been disclosed. Therefore, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For the foregoing reasons, the following claims should be studied to determine the true scope and spirit of this invention.

Claims (4)

1. refrigerated merchandiser, comprise a showcase that limits product display region, it has the viewing area of an open front, one that link to each other with described showcase and be used to guide the air of first air stream roughly down to pass that this viewing area, front portion first air outlet slit links to each other with described showcase with one along first path and be used to guide the air of second air stream roughly down to pass second air outlet slit of this viewing area, front portion along second path outside first air stream, it is characterized in that, described first air stream is discharged from from this first air outlet slit with first exhaust velocity, described second air stream is discharged from from this second air outlet slit with second exhaust velocity, and described second exhaust velocity is about 1.4 times of described first exhaust velocity at least.

2. refrigerated merchandiser as claimed in claim 1 is characterized in that, described second exhaust velocity arrives in about 1.8 the scope about 1.4 with the ratio of described first exhaust velocity.

3. refrigerated merchandiser as claimed in claim 1 is characterized in that, the described first air stream comprises colder air relatively, and the described second air stream comprises relatively warm air.

4. refrigerated merchandiser as claimed in claim 1 is characterized in that, the described second air stream comprises surrounding air.

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