EP2336690A1

EP2336690A1 - A method of generating air curtain for refrigerated display case

Info

Publication number: EP2336690A1
Application number: EP09460057A
Authority: EP
Inventors: Tomasz Kukla; Krzysztof Swoboda; Grzegorz Ozóg; Mariusz Stankiewicz; Lech Gold
Original assignee: Jbg-2 Sp Zoo
Current assignee: Jbg-2 Sp Zoo
Priority date: 2009-12-17
Filing date: 2009-12-17
Publication date: 2011-06-22

Abstract

The invention concerns the generation of an air curtain of a display case, flowing downwards from the top along the front of an open display chamber. The air curtain consists of an internal cooler air flow and an external warmer air flow.

The external warmer air flow is generated by sucking in at the bottom of the display case the cooled air supplemented by air from the surroundings. These two streams are mixed, levelling the temperature, and next the air is sent to the upper part of the display case, from which it is directed downwards in the form of an external flow of the air curtain. Flows with different temperatures are isolated from each other during the transport through channels.

Description

The invention comprises the method of generating an air curtain for refrigerated display case, particularly for vertical one.
Refrigerated display cases are usually used in commercial establishments for storage and presentation purposes of food in temperatures lower than the ambient temperature. Such display cases consist of a display chamber with thermally isolated walls and an open front and separated from the surroundings by an curtain of air cooled to a temperature below the temperature of the surroundings.
In the description of claim in Poland no. 367690 ( PCT/FR02/o2814 ), a vertical display case is included in the lower part of which air is sucked in from the outside, cooled down ad transported up, some of the air stream being fed to a display chamber open in the front, and the remaining part of the air stream flowing down to the downwardly directed outlet in the upper wall of the display chamber. The cooled air floes downwards along the front part of the display chamber as a cool air stream, most of it at the bottom of the display case being sucked into the cool air system, losing the remaining part of the air stream that flows into the surroundings.
At the same time, in the upper part of the display case, air from the surroundings is sucked in and directed along the internal cool air stream as an external warm air stream, being released to the surroundings at the bottom.
In order to clearly show the above-mentioned solution, please find enclosed the drawing entitled pos. I, presenting a simplified vertical cross-section of a display case, with cool and warm air flows forming the air curtain.
The disadvantage of the known solution is that it loses part of the cool and warm air streams, thus resulting in greater energy consumption in order to cool the air sucked in from the surroundings.
The solution according to the invention consists in that the external warm air stream of the air curtain is produced by sucking in at the bottom of the display case the cooled air that is a part of the internal cool air stream lost from the flow and supplemented by air from the surroundings. Having been sucked in, the two air streams mix with each other and are sent to the upper part of the display case, from where they are directed downwards as the external stream of the air curtain, with decreased difference in temperatures between the internal and external flows. Different temperature flows are isolated from each other during their transport by channels. Preferably, the external stream of the air curtain flows slower that the internal stream. The temperatures of both internal cool air stream and external warm air stream are lower than the ambient temperature.
The advantage of the presented method is that it enables to recover cold air released to the surroundings from the internal flow in front of the bottom part of the display case, and next to introduce it to the warmer air flow. As an effect of lowering the temperature of the external stream, heat exchange between the flows decreases, and thus less energy is consumed for purposes of cooling the air introduced to the internal stream. The tests conducted proved that energy consumption decreased by a few percent as a result of this.
A side effect of sealing the closed flow of cooler air is removing the reason for lowering the ambient temperature, which decreases the energy consumption for heating the room.
The solution according to the invention is illustrated by a sample embodiment, wherein the air curtain in front of the open-front display chamber of the display case consists of two tangent air flows, flowing generally vertically downwards. The temperature of the internal air flow (closer to the display case) is lower than in case of the external stream (closer to the surroundings) and the former flows more slowly than the latter, this way preventing the two air streams from mixing and their temperatures becoming level.
The internal cool air flow is created by sucking in the air initially from the surroundings near the floor, cooling it down and transporting upwards along the display case, from where it is directed through the outlet downwards, generally vertically, along the open front of the display case. At the bottom, the major part of the internal flow is sucked into the closed circuit and the remaining part flows outside the inlet. The cool air flow in the closed circuit is replenished with the air from external air flow or with the air from the surroundings
The external warm air flow is created by sucking in the air initially from the surroundings near the floor and transporting it upwards along the display case, from where it is directed through the outlet downwards, generally vertically, as the external flow of the air curtain tangent to the cooler air flow. At the bottom, part of the warmer air flow is sucked into the cooler air stream, majority to the closed circuit, and the remaining part is released to the surroundings. The air released to the surroundings is replaced by air sucked in to the closed circuit from the surroundings.
In order to clearly show the solution according to the invention, please find enclosed the drawing entitled fig.1 , presenting a simplified vertical cross-section of a display case, with cool and warm air flows forming the air curtain.
Comparison of both drawings shows the difference of solutions presented thereon, and thus presents the solution according to the invention.

Claims

A method of generating air curtain for refrigerated display case, consisting in generating in front of an open- front display chamber a two-stream air curtain, with temperature diversified in cross-section, into which air is sucked from the bottom and then cooled down and directed generally vertically partly to the selected place of the display chamber, and partly to the outlet in the upper part of the display case, from which it flows down along the front of the display chamber in the form of an internal cooler air flow, and in the bottom part of the display case is sucked into the closed circuit, losing some cooler air from the system, moreover, outside of the internal cool air flow of the air curtain an external warmer air flow is directed from top downwards, characterised by that the external flow is generated by sucking in at the bottom of the display case the cooled air that constitutes the part of the internal stream lost from the system, being supplemented by air from the surroundings, next such air is mixed, with temperatures becoming levelled, ans sent to the upper part of the display case, the flows with different temperatures being isolated from each other during the transport through channels, finally the air is directed downwards in the form of the external flow of the air curtain, with temperature differences between the internal and external flows being reduced.
Method according to claim 1, characterised by that the external flow of the air curtain flows slower than the internal flow.