EP0555137A1 - Method of cooling an open cabinet for display and self-service sale of fresh produce, and equipment for carrying out this method - Google Patents

Abstract

Method of cooling at least one cooled cabinet in particular of an open cabinet for the display and self-service sale of fresh produce, characterised in that:   a) said open cabinets (10, 11, 12) are arranged in the sales premises and provided in known manner with racks for distribution and retrieval of cold air, running through the inner space of the cabinets, the streams of air flowing over the displayed produce and the air being warmed by taking calories exchanged from the produce;   b) there is positioned in a zone which is at a remove in relation to said cabinets (10, 11, 12) and chosen for its convenience of access a central air-cooling unit which comprises mainly an evaporator (6) for refrigerating liquid/gas, and a fan (12), this central unit moreover being supplied with refrigerating agent by a refrigerating assembly;   c) the cold air originating from the evaporator is drawn by forced circulation from said central unit via appropriate ducts (13, 13a, 13b) towards said cabinets (10, 11, 12), the cold air originating from the central air-cooling unit being delivered to cold-air distribution racks which serve the cabinets, racks for air retrieval being connected via recycling ducts (16a, 16b) to said central unit for the return of the air which is warmed by passage through the cabinet and returned towards said evaporator (6) to be cooled there. <IMAGE>

Description

The present invention relates to the field of installations, in particular refrigerated enclosures, such as display cases, bins, shelving, installed in points of sale, in particular self-service and more especially large surfaces, in order to offer the sale of fresh products and allow the consumer to collect them.

We know in commercial installations of the supermarkets type (supermarkets or hypermarkets) furniture of the shelving type comprising a bottom from which emerge superimposed shelves surmounted by a ceiling and resting on a base, the assembly constituting an open enclosure traversed by a cold air flow to ensure refrigeration and good storage conditions for products.

Exhibition furniture is also known, in particular for products of the "caterer" type comprising a display plan for sale supplemented by a window preferably curved backwards and this plan is traversed as before, by a flow of cold air to keep the products at a low temperature compatible with good storage conditions.

In the systems currently known and implemented, a decentralized refrigeration unit is used, for example in a technical room, which in a conventional manner by compression (condensation) and expansion (evaporation) is able to borrow from the external environment the calories necessary for the latent heat of vaporization of the refrigerant and therefore produces cold.

In currently known systems, the condensing unit is connected by appropriate pipes to each piece of furniture to which it sends the refrigerant in the liquid state, with the interposition of a solenoid valve controlled by a thermostat taking the data corresponding to the temperature of the controlled furniture, the solenoid valve being open or closed depending on the cold requirements of all the speakers served.

The refrigerant then crosses within each piece of furniture served a pressure reducer allowing the separation between the liquid phase and the vapor phase; this regulator is controlled by a thermostatic train controlling the rise in temperature of the fluid at the outlet of the evaporator; the refrigerant passes through the evaporator from the liquid phase to the vapor phase, borrowing the latent heat of vaporization from the external medium and causing substantial cooling of the conduits (finned coils) constituting the evaporator.

The evaporator is constantly traversed by a flow of air circulating under the action of a fan and which carries the cold air after passage over the finned tubes of the evaporator towards the bottom and the top of the cabinet from where it is distributed through orifices and ramps to lick all the products located in the open enclosure, the air recovered at the base of the cabinet and heated by passage over the stored products being returned by the fan to the producer evaporator cold.

The temperature on the walls of the evaporator being less than 0 ° and the circulating air being charged with humidity, this results in the formation and accumulation of frost which must be periodically removed; for this purpose, the evaporator is equipped with electrical resistors entering into operation at frequencies and for predetermined durations; during these defrosting periods with production of calories by the electrical resistances, the circulation of the refrigerant and the ventilation are interrupted, causing a parasitic rise in temperature of the furniture and the products it contains.

According to another method, defrosting is obtained by maintaining ventilation and stopping the circulation of the refrigerant for example for 30 to 45 minutes every 6 hours.

Figure 1 to the accompanying drawings shows this conventional diagram of the technical service of a piece of furniture 3 comprising a plurality of shelves 3a, 3b, 3c, and supplied with refrigerant from a refrigeration unit.

The latter comprises a compressor 1a, a coil 1 for removing the heat resulting from compression and a storage 1c c of the refrigerant in the liquid state (high pressure).

This refrigerant reaches the cabinet 3 via appropriate conduits after passing through a solenoid valve 2 according to the cold requirements as previously indicated; the refrigerant then passes through the expansion valve 4 controlled by the thermostatic train 5 to arrive at the evaporator 6 where the production of cold intervenes by passing from the liquid phase to the gaseous phase of the refrigerant.

This technique has indisputable advantages which are well known and appreciated.

Its reliability has been demonstrated for many years and its conventional implementation is well assimilated by professional installers.

The pipes and conduits circulating the refrigerant between the condensing unit and the furniture are of small diameter, which allows this connection to be integrated into the sites.

On the other hand, this design and this type of embodiment have drawbacks which must be emphasized and which have led to the search for another approach.

Each piece of furniture contains a large number of refrigerating components, which raises the cost price and above all makes it difficult to carry out the necessary interventions on these components in the circumstances of temporary breakdown.

It is then necessary to empty the furniture and carry out interventions at night or on Sunday; which represents long handling operations and expensive and handicaps the operating conditions.

By this same it is not possible to directly and visually control the components which are concealed being generally located behind the rear face or in the bottom of the cabinet.

The system does not provide for filtration of the air circulated to bring frigories to the stored products.

The refrigeration equipment being an integral part of the furniture, and increasing as indicated the cost price, this solution limits the possibilities of change in the fittings and architecture and interior decoration of the stores, any modification being thereby costly. , because the refrigeration systems integrated into abandoned and reformed furniture are thus lost.

Finally, periodic defrosting leads to parasitic temperature rises which increase the refrigeration balance of the farm and adversely affect the conservation of the products.

The invention aims to remedy these drawbacks while retaining the advantages of the conventional system, in particular the reliability of the tested components, their easy implementation.

According to a first object, the invention makes it possible to limit the number of technical components.

According to a second object, the invention makes it possible to separate the exposure function (at the furniture level) from the thermal function (production of cold).

According to yet another object, the invention allows technical interventions without emptying the furniture and it allows permanent visual control of the components.

The invention also makes it possible to ensure treatment of the air with a view to its purification before its recycling.

Finally, the invention will make it possible to change the furniture and to ensure possibilities of periodic renewal of the stores with an adaptation of the interior decoration and architecture to the taste of the day or of the operator without causing modification and scrapping. technical installations previously integrated into the exhibition furniture.

• a) on dispose dans le local de vente lesdites enceintes ouvertes pourvues de façon connue en soi de rampes et orifices de distribution et de reprise d'airfroid, parcourant l'espace intérieur des enceintes, les filets d'air léchant les produits exposés et l'air se réchauffant par l'emprunt de calories échangées depuis les produits;
• b) on met en place dans une zone déportée par rapport auxdites enceintes et choisie pour ses commodités d'accès, une centrale de refroidissement d'air comportant principalement un évapo- rateurde liquide-gaz frigorigène et un ventilateur. Cette centrale est par ailleurs alimentée en fluide frigorigène par un groupe frigorifique;
• c) on entraîne par circulation forcée l'air froid provenant de l'évaporateur de ladite centrale de refroidissement d'air par des gaines appropriées vers lesdites enceintes, l'air froid provenant de la centrale de refroidissement étant délivré à des rampes de distribution d'air froid desservant les enceintes, des rampes de reprise d'air étant raccordées par des gaines de recyclage à ladite centrale de refroidissement d'air pour le retour de l'air réchauffé par passage dans l'enceinte et renvoyé vers ledit évaporateur pour y être refroidi.

To this end, the invention relates to a process for supplying cooling air to at least one refrigerated enclosure, in particular an open enclosure for the exhibition and self-service sale of fresh products, characterized in that :

• a) there are available in the sales room said open enclosures provided in a manner known per se with ramps and orifices for distributing and recovering cold air, traversing the interior space of the enclosures, the air streams licking the exposed products and l air heating by borrowing calories exchanged from products;
• b) an air cooling unit comprising mainly a liquid-refrigerant evaporator and a fan is installed in a zone remote from said enclosures and chosen for its access convenience. This power plant is also supplied with refrigerant by a refrigeration unit;
• c) cold air from the evaporator of said air-cooling unit is forced to circulate through suitable ducts towards said enclosures, the cold air coming from the cooling unit being supplied to distribution manifolds d cold air serving the enclosures, air return ramps being connected by recycling ducts to said air cooling unit for the return of the air heated by passage through the enclosure and returned to said evaporator for be cooled.

According to one embodiment of said method, a certain quantity of secondary air taken from the ambient atmosphere or from the room is mixed on arrival on the enclosure to be refrigerated with the flow of cold air or primary air coming from the refrigeration unit. return air to adapt, if necessary, the flow and temperature characteristics of the cold air serving said enclosures.

According to yet another development of the method of the invention, the cold air entering the top of the enclosure is distributed and the heated air is taken up at the base of the enclosure, each time by two twin ramps, ie respectively two twin distribution ramps and two twin recovery ramps, the two ramps in each twin set comprising an opposite direction of circulation, from one ramp to the other, each ramp ending in a dead end, the dead ends being in head-to-tail position, so as to allow a balanced distribution of the total flows throughout the twin ramps.

According to a further development of the invention, there are two twin air cooling units, allowing alternating defrosting operations as well as maintenance, upkeep and repair operations without interrupting the supply of the speakers.

The invention also relates to an installation for implementing the method described above and for ensuring the refrigeration of open enclosures for exposure to the self-service sale of fresh products, the installation comprising at least one enclosure open to receive the products on support members and means for distributing and recovering the heated air having passed through the interior space of the enclosure, the installation is characterized in that the distribution and recovery ramps serving each enclosure are connected by means of forced circulation of cold air to at least one air cooling unit of the known type and comprising a fan-evaporator assembly of refrigerant (liquid-gas), the cooling unit of air being offset from to said enclosures, which are supplied not with refrigerant but with cooling air.

More specifically, the air cooling central serves a plurality of enclosures by a network of cold air distribution ducts leading to distribution ramps serving each enclosure and by return ducts connecting each enclosure to the central cooling 'air, the recycled air from each enclosure being returned to the evaporator of the air cooling unit for cooling and to leave at low temperature to the enclosures.

According to a further development of the invention, each enclosure or group of enclosures comprises at least one member such as an ejector-convector for the purpose of mixing the primary air distributed from the central refrigerating group with the secondary air withdrawn on the ambient atmosphere or in the return air at the base of the speakers.

Advantageously, the enclosures include ramps for distributing cold air, preferably at their top, and air return ramps, preferably at their base, and the distribution ramps as well as the return ramps are in even number, each set of ramps, respectively for distribution or recovery comprising in equal number of opposite direction of flow of traffic and head to tail, the distribution and recovery flows, resulting from the sum at all points of the flows of the associated ramps being balanced while along said ramps.

According to a further development of the invention, the installation comprises two twin air cooling units, allowing alternating operation in particular for defrosting, maintenance, upkeep and repair operations.

And advantageously still, each air cooling unit comprises means for purifying the circulating air, in particular by filtration and / or washing.

According to another characteristic of the invention, the distribution and / or return booms diffuse and / or absorb air towards or from the enclosure opened by a porous surface such as a fabric, a nonwoven, or a perforated wall.

And according to another embodiment, the ramps are arranged independently, for example being superimposed or attached, with respect to the furniture constituting the exhibition means, said furniture thus being interchangeable without appreciable modification of the distribution network and / or of cooling air intake.

• - la figure 1 (précédemment commentée) représente une vue schématique d'une installation conventionnelle;
• - la figure 2 représente un schéma de principe d'une installation conforme à l'invention;
• - la figure 3 représente un schéma montrant la disposition tête-bêche des rampes de distribution et de reprise;
• - la figure 4 montre une variante de réalisation dans laquelle l'alimentation de chaque enceinte comporte un éjecto-convecteur pour le mélange d'air secondaire induit pour rejoindre l'air primaire provenant de la centrale frigorifique;
• - la figure 5 représente une vue de principe de la circulation de l'air de réfrigération au niveau de chaque enceinte ouverte;
• - la figure 6 montrant un exemple de raccordement des rampes inversées (pour la distribution ou la reprise de l'air).

Other characteristics and advantages of the invention will emerge from the description which follows and which is given in relation to a particular embodiment and with reference to the appended drawings.

• - Figure 1 (previously commented) shows a schematic view of a conventional installation;
• - Figure 2 shows a block diagram of an installation according to the invention;
• - Figure 3 shows a diagram showing the head-to-tail arrangement of the distribution and take-back ramps;
• - Figure 4 shows an alternative embodiment in which the supply of each enclosure comprises an ejector-convector for the secondary air mixture induced to join the primary air from the refrigeration plant;
• - Figure 5 shows a principle view of the circulation of refrigeration air at each open enclosure;
• - Figure 6 showing an example of connection of the inverted manifolds (for air distribution or return).

In the method and the device according to the invention, the enclosure to be cooled is identical in all respects in its functional purpose of exposing fresh products to the devices which are currently known, whether they are vertical pieces of furniture with superimposed shelves. , or horizontal low cabinet with curved display case.

Inside each enclosure, the circulation of cold air is carried out in a conventional manner, the cold air being blown in from the upper part and recovered at the lower part to be recycled to an air handling unit in which the air is cooled.

In this design, the cold air production unit is independent of the furniture to which it is connected by outward circulation ducts and return circulation ducts, and the unit can therefore be moved to an area chosen for its convenience of access and which may possibly be far from the furniture served; this plant could be installed for example under the roof, or on the roof, in a technical room, in the basement or in the upper parts above the false ceiling of the store.

We see in Figure 2 a block diagram which represents on one side the air cooling unit and which serves by a network of air circulation ducts decentralized and peripheral furniture; the same references have been used in FIG. 2 to designate the same members as in FIG. 1, these members being moreover conventional and their implementation not being specific to the invention, which is oriented on the arrangement of the members technical, all the refrigerating components being transferred and centralized at the level of the air cooling unit, the furniture then being no more than a simple air-conditioned body, empty of all technical equipment.

According to Figure 2, we see that we put in place under the reference 1 a refrigeration unit composed as previously indicated of a compressor feeding it through the coil 1 b for the de loss of calories associated with compression and the passage of the vapor phase into the liquid phase, the reservoir 1c of refrigerant in the liquid state and under high pressure in the reservoir.

This reservoir feeds through the expansion valve 4 the exchanger or evaporator 6 in which the refrigerant evaporates by drawing from the medium passing through the exchanger 6 the calories necessary to compensate for the latent heat of vaporization.

The refrigerant circuit in the gaseous state then joins the compressor 1a.

The exchanger 6 is here streamlined to allow the passage of air intended to supply each of the pieces of furniture 10, 11 and 12, which are deported and embedded in the layout of the store, while the refrigeration unit 1 is located in a remote room chosen for its convenience, the air cooled after passing over the exchanger 6 is circulated by the circulator or turbine 12 and from there is sent by a main pipe 13 to the furniture 10, 11, 12 through the branches 13a, 13b .

The regulator 4 as the circulator 12 can advantageously be controlled by the circuits 14, 15 from thermal probes taking the characteristic data of the recycled air on the return pipes so as to adapt the production of cold by acting on the one hand on the expansion valve (quantity of refrigerant admitted into the evaporator) and on the flow rate (speed of circulation of circulator 12), this depending on the cooling requirements at the level of the furniture.

The number of pieces of furniture is obviously not critical and they were diagrammed here three in number, a refrigeration unit according to its power and its air flow which can be calculated to supply all the pieces of exhibition furniture with fresh products of a hypermarket.

Still according to FIG. 2, it can be seen that the cold air coming from the central unit blown into the top of the cabinet and along the rear wall (by way of example) is taken up at the base and through the pipes 16a, 16b to reach the central recovery column 16 which routes all of the recycled air from the base of the furniture to the central and more specifically to the exchanger 6.

According to a development of the invention shown in FIG. 3, it can be seen that when it arrives on an individual piece of furniture 10, the air coolant distribution pipe splits into two parallel and twin ramps, each ramp 17a, 17b ending in a cul de -bag 18a, 18b near which the residual pressure is considerably reduced.

As can be seen in FIG. 3, the two distribution ramps are arranged head to tail so that the direction of circulation in each ramp is opposite to that of the previous ramp.

It is understood that under these conditions, an automatic self-balancing of the flow rates is obtained throughout the two twin booms since at one end a boom close to its inlet will tend to deliver a greater quantity of air given the pressures therein. reign, while as one approaches the end wall in a dead end, the pressure decreases due to the air which has already escaped; so that along each ramp the decreasing pressure gradient determines a decreasing flow gradient.

But as the two gradients are inverted, at all points they complement and complement each other so that the total flows are equal all along the two twin ramps.

The number of ramps is not critical, the important thing being because of the system which requires that with a unidirectional ramp is associated a reverse unidirectional ramp, the number of ramps is even.

At the base of the cabinet 10, there are the two identical ramps 19a, 19b which provide recovery and recovery of the air having passed through the enclosure (and partially drawn from the ambient environment) and as previously exposed the two recovery ramps being arranged head to tail, their inlet flow will be identical throughout the length of the cabinet.

One can thus realize air distributions with a homogeneous flow throughout linear of great length going up to 10 meters, even 20 meters, the realization being limited only by the section of ducts connecting the furniture and the central , this depending on the interior decoration and the installation possibilities.

According to Figure 4, we can still see a development of the invention which is shown schematically and in which the refrigeration plant 1 is supplemented in addition to the fan 12 by means located upstream and comprising a filtration assembly 20, the cold battery consisting of the evaporator 6 followed by a washing assembly 22 completed by a drip screen 23.

The air thus purified is cooled is circulated by the turbine 12 to be blown by the sheath 13 to the network serving the furniture, as previously exposed.

In the context of this development, a cooled air is used comprising advanced characteristics, in particular in temperature (low temperature) and in flow (kinetic energy).

And at the level of each piece of furniture, the air coming from the central unit 1 is introduced into an ejector-convector 24 which mixes a part of ambient air with primary air coming from the central unit, in order to breathe an air of cooling of appropriate average characteristics and suitably adjusted at all times as required.

In this case, the primary air circulation ducts are not overdimensioned since it can thus transport large quantities of frigories under a small section, the primary air being tempered by the reinjection of secondary air when it is put into service in each piece of furniture.

The application of this principle is achieved by the use of a high pressure air handling unit with reaction fan to obtain a total monometric height of approximately 400 mm of water column; possibly more if possible. The only objective in this area is to limit the section of the ducts to what is strictly necessary, thereby facilitating the installation and operating facilities.

The mechanical strength of the ducts which is often limiting in climate engineering is not here an imperative or a constraint insofar as said primary air ducts run only over limited lengths.

It will of course be careful to pay particular attention to the noise level of the ejector-convector constituting a "relaxation box" between the high pressure primary air inducing, by its stroke, the ambient air entrained in the mixture.

FIG. 5 represents a more detailed view of the distribution circuits of the respectively blown air (cold air introduced) and taken up in the cabinet.

We see that in the context of the invention the refrigerated cabinet retains its traditional appearance but is overcome by the air distribution system with the ramps 17a, 17b, 19a, 19b mounted head to tail and reverse circulation allowing self-compensation of pressure drops.

Advantageously, these ramps open onto the medium they serve (interior space of the refrigerated cabinet) by a porous surface (non-woven fabric, perforated fabric, honeycomb) allowing the diffusion of air in the medium served. According to FIG. 6, each ramp is located at equal distance from its binoculars from the power plant.

The upper part of the cabinet can be either integrated into the latter or placed (being secured by any means, in particular by screwing) on the cabinet.

Under these conditions, it is very easy during the redevelopment and "remodeling" of the interior layout and of the architectural repair and decoration to remove the furniture to set up a new structure adapted to taste and aesthetic sought while leaving in place the technical superstructure made up besides only of the network of distribution and take-back ramps.

In all cases, the piece of furniture is made up only of static elements for resting, storing and exhibiting objects, while it does not contain any moving mechanical parts or any electrical equipment likely to be a cause. of breakdown.

This automatically avoids any risk of seeing either the entire contents of a piece of furniture lost as a result of a poorly detected breakdown, or the obligation to have to clear all the contents of a piece of furniture in order to return it to a cold room for maintenance and repair, the latter being also made particularly difficult to the extent that it must be done in situ so either in the presence of consumers, which does not give a good image of the establishment or in night or Sunday rest periods.

According to the development which is shown in Figure 7 schematically, we see that we have set up two evaporators 6a, 6b which are isolated by movable flaps 25a, 25b, 25c, 25d (in the closed position) and the four flaps 26a, 26b, 26c, 26d (in the open position).

Each of the evaporators 6a and 6b belongs to one of the two twin plants which equip the entire installation.

It can be seen from this figure that while a central unit serving the evaporator 6a is isolated, the other unit serving the evaporator 6b is in the active position and can thus fulfill its function.

During the defrosting phases, it is easy to put the central unit serving the evaporator 6b in the inactive position, while immediately the other central unit serving the evaporator 6a is switched on, the flaps 25a, 25b, 25c , 25d then being released to allow air circulation.

Thus defrosting can be carried out safely without adding parasitic calories to the entire installation.

We no longer fear the risks of breakdown and decommissioning with the potentially catastrophic consequences that may result for the products stored since a breakdown can be detected by means of standby and automatically cause the commissioning of the other central .

It can be seen that a perfectly balanced assembly is thus produced according to the invention which has a certain number of advantages compared to the previous system both in terms of production and installation and in terms of operation.

Claims (7)

1. A method of supplying frigories to at least one open refrigerated enclosure for the display and self-service sale of fresh products, in which: a) the said open enclosures (10, 11, 12) are provided in the sales room provided with distribution and return air cooler rails, traversing the interior space of the enclosures, the air streams licking the exposed products and l air heating by borrowing calories exchanged from products; b) a remote zone is set up in relation to said enclosures (10, 11, 12) and chosen for its convenience of access, a air cooling unit comprising an exchanger (6) and a circulator (12) and also being supplied with refrigerant, by a refrigeration unit, or with refrigerant.
characterized in that the cold air from the said central unit is forced into the said enclosures (10, 11, 12) by forced circulation, the cold air being supplied to cold air distribution manifolds opening at the top of the enclosure and the heated air is taken up at the base of the enclosure, each time by two twin ramps, that is to say two twin distribution ramps (17a, 17b) and two twin return ramps (19a, 19b) , the two ramps in each paired assembly comprising an inverted direction of circulation, from one ramp relative to the other, each ramp ending in a dead end 18a, 18b), the dead ends being in head to tail position. 2. Method according to claim 1, characterized in that there are two twin exchangers at the air cooling unit. 3. Installation for the implementation of the method according to one of claims 1 or 2, intended to ensure the refrigeration of open enclosures for exposure to the self-service sale of fresh products, the installation comprising at least an open enclosure (10, 11, 12) for receiving the products on support members and means for distributing and recovering the heated air having traversed the interior space of the enclosure, the installation comprising ramps of distribution (17a, 17b) and return (19a, 19b) serving each enclosure are connected by means (13, 16, 12) of forced circulation of cold air to at least one air cooling unit (6) comprising a refrigerant (liquid-gas) evaporator or exchanger, the air cooling unit being offset relative to said enclosures, which are supplied not with refrigerant but with refrigerant air,
characterized in that the enclosures (10, 11, 12) have air-cold distribution ramps, preferably at their top, and return air ramps, preferably at their base, the distribution ramps (17a, 17b) as well as the recovery ramps (19a, 19b) being in an even number, each set of ramps, respectively for distribution or for recovery comprising in equal number of ramps with opposite direction of flow and upside down, the distribution rates and recovery, resulting from the sum at any point of the flows of the associated ramps being balanced throughout said ramps. 4. Installation according to claim 3, characterized in that it comprises two evaporators, exchangers or combination of two or two twin air cooling units, allowing alternating operation in particular for defrosting operations, maintenance, maintenance and repair. 5. Installation according to one of claims 3 or 4, characterized in that each air cooling unit comprises means for purifying the circulating air, in particular by filtration and / or washing. 6. Installation according to one of claims 3 to 5, characterized in that the distribution ramps (17a, 17b) and / or return (19a, 19b) diffuse and / or absorb the air to or from the open enclosure by a porous surface such as a fabric, a nonwoven, or a perforated wall. 7. Installation according to one of claims 3 to 6, characterized in that the ramps are arranged independently, for example being superimposed or attached, relative to the furniture constituting the exposure means, said furniture thus being interchangeable without modification sensitive to the distribution and / or return air network for refrigeration.

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