WO2006032934A1

WO2006032934A1 - Air-curtain system for commercial open front refrigerators and display cabinets

Info

Publication number: WO2006032934A1
Application number: PCT/GR2005/000029
Authority: WO
Inventors: Athanasios Katsanevakis
Original assignee: Enervac-Flutec Ltd
Priority date: 2004-09-20
Filing date: 2005-09-16
Publication date: 2006-03-30

Abstract

System of air curtains for commercial refrigerators and display cabinets of the open front type. The system is comprised by individual air curtains using cool air at the refrigerator's front, in between shelves. The air curtains have height equal to the distance between shelves and width equal to the cooling cabinet width. To create the air curtains the shelves are used as supply and return ducts, providing short height air curtain and laminar conditions. Alternatively, slim air ducts may be employed, and placed at the same height as the shelves. Such air curtains ensure reduced cooling losses to the environment, since the supplied cool air has low velocity and mixing with the ambient air is limited. The humidity trapped from the ambient air during the air curtain operation is also limited. During the refrigerator's operation, use by the customers or replacing products on the shelves, disturbs the operation of only one air curtain from the lot, leading to further reduction of cooling losses to the environment. The air curtain system may be used by commercial refrigerators and display cabinets of the open front type, for reduced energy consumption and more efficient operation of the refrigerator or the display cabinet, having reduced losses to the environment. Furthermore the refrigerators may be more practical for all customers and especially children and the disabled, since a bin area is not necessary for their operation.

Description

Air-curtain system for commercial open front refrigerators and display cabinets

TECHNICAL FIELD

The present invention concerns a new type of open front commercial refrigerator. In such open front refrigerators and display cabinets, air curtains are employed to preserve cooling conditions within the cabinet and to prevent ambient air from entering the products cooling area.

DESCRIPTION OF THE PRIOR ART In order to minimize cooling losses from open front refrigerators to the environment several methodologies have been already patented. The following patents introduce systems of parallel air curtains, employed at the open cabinet:

1. US4938034A/HILL REFRIGERATION CORPORATION - July 3, 1990 ;

2. US4269037A/ KARASHIMA - May 26, 1981 ; 3. EP0709046A/SANYO ELECTRIC CO. LTD - May 1 , 1996 ;

4. US2003172670A/VORMEDAL - September 18, 2003 ;

5. FR2828079A/ BONNET NEVE S.A. - February 7, 2003.

The main common characteristic of all of the above documents is the employment of systems of parallel and adjacent air curtains formed simultaneously at the refrigerator open front. In general, an air curtain works in the following manner : Cool air exits vertically the air distribution system at the upper end at the front of the refrigerator cabinet, through slot openings. The air returns at the lower end at the front of the cabinet and enters the cooling air circuit, after passing in front of the shelves. Thus, the air curtain length equals the height of the front opening of the cabinet and it's width equals the cabinet width. Since the cool air has to travel a long distance, equal to the refrigerator cabinet open front, significant mixing with the ambient air occurs. This results in a significant increase of the cool air temperature and moisture content, and therefore in increased cooling losses. Thus, the commercial refrigerator requires increased energy consumption for it's operation. In order to overcome this fact, multiple air curtains are employed, involving external ones formed by ambient air supply, flowing in parallel to the cool air curtains and in such a manner as to entrap the cool air within the cabinet. This is described within the patents mentioned above. This also prevents direct mixing between the cool air and the stationary ambient air, providing an outer velocity field suppressing the underline turbulent eddies and reinforce the inner jet inertia. This of course requires several air supply circuits. Moreover, the air curtain operation is disturbed by any movement close to the refrigerator, as well as by the use of the refrigerator by the customers when reaching for a product in the cooling cabinet. For the undisturbed operation of the air curtain relatively high air velocities are required, accompanied by a calibrated system of air supply circuits.

DESCRIPTION OF THE INVENTION

The present invention eliminates the above-described disadvantages of the open front refrigerators and display cabinets of the prior art. The invention consists of a system of individual air curtains operating between the shelves, thus having height equal to the distance between neighboring shelves. The system of the proposed air curtains employs the shelves as air ducts for supply and return. Each air curtain operates in completely independent manner from the others. This system may be coupled with an external ambient air curtain, without this to be regarded necessary. Advantage of the invention is that the cool air flow is distributed at the front area by means of the shelves which are used as air ducts, or by employing slim air ducts at the shelves front side. Air is supplied vertically from every upper shelve and collected at the corresponding lower shelve. Each intermediate shelve constitutes two air ducts. From the upper air duct the cool air jet over the shelve returns, while from the lower air duct cool air is supplied to form an air curtain towards the lower shelve. In this way, air from the cooling system is distributed to each shelve and to the cabinet ceiling. Then air is supplied vertically to the corresponding lower shelve or cabinet floor forming air curtains; then air is collected at each shelve or at the bottom of the cabinet, and enters the cooling circuit. In this way limited height air curtains in between succeeding shelves are formed. The advantages of such an arrangement against prior art is on one hand the ability for better control of the air curtain velocity and temperature, the limited cool and ambient air mixing due to the short traveling distance of the supplied cool air and the relatively low initial velocities required. On the other hand the individual character of the air curtains and their compact size make them less affected by movement in front of the refrigerator, while when the refrigerator is in use by a customer, only the air curtain operating at the certain shelve is disturbed, leaving the operation of the rest uninterrupted. Furthermore, the cool air distribution system is such as to allow for different flow rates towards each shelve. The system's operation can be optimized based on the geometrical characteristics each individual air curtain is supposed to have. These characteristics include, apart from the air curtain width and the preferred height, the supply and return openings that may be adjustable, in order to provide the required velocity distribution of the air jets. Another advantage of the present invention is that it does not require any bin area, in comparison to prior art designs, making product selection by the customers easier. The customers, and especially children and disabled people, may approach displayed products more easily, providing the invention with another competitive advantage.

Claims

1. Air curtain system for commercial refrigerators and display cabinets having an open front cabinet without door, characterized by individual air curtains formed by cool air supplied at the front part of the upper shelve and return at the front part of the lower shelve, throughout the cabinet height and width.

2. Air curtain system, according to Claim 1, comprised by the lot of individual air curtains in between shelves; each individual air curtain has a height equal to the distance between shelves; the supplied cool air flow rate for the formation of each individual air curtain is proportional to the distance between shelves.