EP0427648B1 - Method and device for the transfer of cold - Google Patents

Abstract

According to the invention, in an intermediate loop (2), a cold transfer fluid, which is in diphase form, that is to say in the form of a homogeneous mixture of water and ice for example, is made to circulate. This fluid undergoes heat exchange, on the one hand with a primary cold source and on the other hand with the different secondary sources of heat represented by each enclosure (1) to be cooled. <IMAGE>

Description

The present invention relates to the transfer of cold into a plurality of chambers to be cooled, from a single intermediate refrigerant fluid, itself cooled by heat exchange with a single refrigerant source.

By enclosure is generally meant any heat source, that is to say any medium capable of directly or indirectly yielding heat. It may be a substantially closed enclosure, such as a cold room, a room for industrial or domestic use to be air conditioned, such as a dwelling house. It can also be a medium to be cooled, contained in a container or a so-called enclosure, such as a liquid or fluid charge; in this regard, to describe the present invention by way of example, reference will be made to the field of winemaking, and more specifically to the cooling of fermentation tanks, to thermally control or master this biological process.

• on établit un circuit de circulation intermédiaire d'un fluide frigo-porteur ; ce dernier est triphasique, en ce qu'il comprend une phase liquide constituée d'eau et d'un fluide frigorigène, à savoir un réfrigérant tel que celui connu sous la dénomination R-114, et d'une phase solide, à savoir des cristaux de glace, le tout en mélange homogène ; ce circuit est à la fois fermé, en ce sens que le fluide frigo-porteur forme une boucle de circulation, et ouvert, en ce sens que la boucle du fluide frigo-porteur comporte un point d'injection du fluide frigorigène sous forme liquide, et un point d'extraction du fluide frigorigène sous forme vapeur, lesquels appartiennent à un circuit frigorique traditionnel transportant le fluide frigorigène
• on refroidit le fluide frigo-porteur par échange de chaleur direct, c'est-à-dire au contact l'un de l'autre, entre le fluide frigo-porteur triphasique et le fluide frigorigène sous forme liquide
• pour chaque enceinte ou récipient à refroidir, on dérive du circuit de circulation intermédiaire, un courant partiel du fluide frigo-porteur, on refroidit le milieu à refroidir dans l'enceinte par échange de chaleur avec le courant partiel dérivé, et on renvoie le courant partiel réchauffé, dans le circuit de circulation intermédiaire, en amont de la dérivation du courant partiel suivant prélevé sur le fluide frigo-porteur, selon le sens de circulation de ce dernier.

In accordance with document US Pat. No. 3,906,742, a cold transfer method has been described as stated in the preamble of claim 1, for conditioning the air in several rooms or separate enclosures. According to this process:

• an intermediate circulation circuit of a coolant fluid is established; the latter is three-phase, in that it comprises a liquid phase consisting of water and a refrigerant, namely a refrigerant such as that known under the name R-114, and a solid phase, namely ice crystals, all in a homogeneous mixture; this circuit is both closed, in the sense that the coolant forms a circulation loop, and open, in the sense that the coolant loop has a point of injection of the refrigerant in liquid form, and a point of extraction of the refrigerant in vapor form, which belong to a traditional refrigeration circuit transporting the refrigerant
• the coolant is cooled by direct heat exchange, that is to say in contact with each other, between the three-phase coolant and the refrigerant in liquid form
• for each enclosure or container to be cooled, there is derived from the intermediate circulation circuit, a partial stream of the coolant, the medium to be cooled in the enclosure is cooled by heat exchange with the derivative partial stream, and the current is returned partially heated, in the intermediate circulation circuit, upstream of the derivation of the next partial current taken from the coolant, according to the direction of circulation of the latter.

According to this method, the refrigerating power delivered by the refrigerant, and more precisely by the aforementioned refrigerant circuit, is adjusted, as well as the circulation rate in the loop of the refrigerant, relative to the total refrigerating power consumed in the plurality enclosures to be cooled, so as to have a refrigerating fluid in circulation, comprising the two phases of water, namely liquid and solid, in melting equilibrium, and mixed with each other so homogeneous, at least in the part of the circulation circuit on which the partial cooling currents are derived or pitted.

Such cooling has various drawbacks.

Each branch circuit ensures the circulation of a partial current of the three-phase refrigerant fluid, of relatively low flow rate, towards the enclosure to be cooled. Experience shows that under these conditions the ice crystals of the solid phase are likely to agglomerate, and to lead to a complete obstruction of each branch circuit, in particular during periods of operation when the cooling power delivered may temporarily exceed the total cooling power consumed. Such an obstruction can also lead to deterioration of the circulation organs or control of the partial flow delivered, such as pumps, valves.

The communication of the intermediate circulation circuit of the refrigerant fluid and of the refrigeration circuit proper obliges to apply the constraints of the second to the first, and more precisely to have a completely sealed intermediate circulation circuit, in particular vis-à-vis refrigerant in vapor form.

The present invention aims to remedy all these drawbacks.

The subject of the invention is a method and device allowing circulation of the coolant fluid, without obstruction by the solid phase of said fluid, in each branch circuit, but also at any point of the intermediate circuit, while allowing an embodiment (in particular mounting), simple and usual of the aforementioned circulation circuit.

• a) le fluide frigo-porteur est diphasique, et non triphasique comme précédemment, et consiste en les phases liquide et solide d'un même corps, par exemple de l'eau ; ce fluide frigo-porteur est refroidi par échange de chaleur indirect, c'est-à-dire sans contact l'un avec l'autre, avec le fluide frigorigène;
• b) le circuit de circulation intermédiaire consiste en une boucle de libre transport du fluide frigo-porteur, c'est-à-dire sans interruption ou passage dudit fluide au travers de tel ou tel organe autre qu'une pompe de circulation ou une vanne de contrôle, par exemple une capacité intermédiaire de stockage, ou un filtre ;
• c) on dérive chaque courant partiel, uniquement sur la phase liquide du fluide frigo-porteur en circulation dans la boucle ; et on renvoie le courant partiel liquide réchauffé dans la même boucle.

According to the invention, in combination:

• a) the coolant fluid is two-phase, and not three-phase as before, and consists of the liquid and solid phases of the same body, for example water; this refrigerating fluid is cooled by indirect heat exchange, that is to say without contact with each other, with the refrigerant;
• b) the intermediate circulation circuit consists of a loop for free transport of the coolant, that is to say without interruption or passage of said fluid through such or such a member other than a pump circulation or a control valve, for example an intermediate storage capacity, or a filter;
• c) each partial current is derived, only on the liquid phase of the refrigerant fluid circulating in the loop; and the liquid partial stream heated in the same loop is returned.

Preferably, according to the direction of circulation of the coolant fluid in the loop, each partial liquid stream heated is immediately returned, immediately downstream or upstream of the bypass of the same current, that is to say respectively upstream of the bypass of the next partial current on the same loop, or downstream of the return of the bypass of the previous partial current.

Thanks to the invention, each heated partial current, in the liquid state, reinjected into the intermediate circulation circuit, is immediately cooled, by fusion of the solid phase of the coolant, before the latter circulates partly in the next branch circuit, or in the same branch circuit. Everything happens as if each container or enclosure was cooled by fusion of the solid phase of the coolant, that is to say by extraction of each said container or enclosure from the latent heat necessary for the fusion of the solid phase .

In this way, for a relatively limited dimensioning of the intermediate circulation circuit, in particular in section, it appears possible to transport a relatively large quantity of frigories towards the various chambers to be cooled, and this without obstruction of the various circuits, and with a balanced distribution. frigories to the different branch circuits.

Preferably, the refrigerant fluid comprises only ice in pasty form, in melting equilibrium in water. Since the ice floats above the water, a turbulent regime is established in the coolant fluid, to maintain its pasty form, with dissolution of the ice.

• la figure 1 représente un dispositif ou installation de transfert de froid selon l'invention, dans le cadre d'une exploitation vinicole comportant une pluralité de cuves de fermentation d'une vendange
• la figure 2 représente, à échelle agrandie, une vue en coupe du piquage en phase liquide d'un circuit de dérivation, sur la boucle intermédiaire du fluide frigo-porteur
• la figure 3 représente, à échelle agrandie, une vue en coupe du retour du courant partiel prélevé dans la boucle intermédiaire, à partir du même circuit de dérivation
• les figures 4 et 5 représentent deux modes de raccordement entre un niveau supérieur et un niveau inférieur d'une même boucle de circulation intermédiaire.
• la figure 6 représente un autre mode de branchement d'un circuit de dérivation sur la boucle intermédiaire.

The present invention is now described with reference to the accompanying drawings, in which:

• FIG. 1 represents a device or installation for transferring cold according to the invention, within the framework of a wine-growing operation comprising a plurality of fermentation tanks for a harvest
• 2 shows, on an enlarged scale, a sectional view of the liquid phase connection of a bypass circuit, on the intermediate loop of the coolant
• Figure 3 shows, on an enlarged scale, a sectional view of the return of the partial current drawn in the intermediate loop, from the same branch circuit
• Figures 4 and 5 show two modes of connection between an upper level and a lower level of the same intermediate circulation loop.
• FIG. 6 shows another method of connecting a branch circuit to the intermediate loop.

In accordance with FIG. 1, a cold transfer installation according to the invention makes it possible to cool a plurality of tanks 1a to 1h, placed in the same place, and containing for all or part of them a load of grapes or harvested grapes . The tanks 1c and 1g have been shown in detail in FIG. 1.

An intermediate circuit 2 makes it possible to circulate a coolant fluid, namely two-phase water in melting equilibrium, these two phases being mixed with one another in a homogeneous manner, for example in the form of a paste or "sorbet", in which ice floats naturally in water. This circuit has the form of a practically closed loop, the outlet 3b of which communicates with the suction of a pump 4, and the inlet of which 3a communicates with the discharge of the same circulation pump 4. Traditionally, the intermediate circuit 2 is equipped with an expansion tank 5 and a filling valve 6, provided at its anti-scale device and filter outlet.

This circuit 2 is practically closed on itself, in the sense that apart from the taps necessary for the evacuation and the supply of coolant fluid, and those corresponding to the entry and exit of each circuit of bypass, there is no other entry or exit of the coolant, which then turns in circles in loop 2, in the homogeneous two-phase state, practically at any point of said loop.

In loop 2, the coolant is freely transported, in the sense that there is no obstacle or organ, other than a pump 4 and the necessary control valves, crossed by the current of said fluid, and coming to thwart the circulation or flow of the latter. Such members could for example be a filter through which the entire flow of the coolant fluid flows; according to the invention, such members are excluded from the path or path of the coolant fluid in the loop.

Advantageously, the loop 2 can be produced by assembling or mounting plastic pipes, for example PVC, connected with suitable seals, for example elastomer seals called "tulip".

On the intermediate loop 2 is connected a thermally insulated reservoir 50 for generating and storing two-phase water in fusion equilibrium. This reservoir or silo communicates with the loop 2, via an inlet conduit 51 equipped with an endless screw 52 for supplying dough or "sorbet", on the suction side of the pump 4; this container communicates with the loop 2, via an outlet conduit 53, with a connection only in the liquid phase of the coolant fluid, upstream of the inlet conduit 51. Internal means (not shown) for turbulence of the water and ice are associated with the container 50. A bypass 54 takes the water in the liquid phase at the foot of the container 50, and returns a mixture of ice and water, at the head of the container 50. This bypass is associated a primary heat exchanger 33, with a scraped surface, in which a refrigerant 21 circulates, belonging to a refrigeration unit.

As shown for tanks 1c and 1g, each bypass circuit, for example 7c, associated with a tank, for example 1c, essentially comprises a secondary heat exchanger 8, placed in the tank, either within the charge during fermentation, either on its surface. The inlet 9 of the exchanger 8 communicates with the intermediate loop 2, by means of a nozzle controlled by a valve 10 and a pump 11. The outlet 13 of the same exchanger communicates with the intermediate loop 2, in the form of a nozzle return controlled by a valve 12. As shown in Figure 2, the input 9 of each branch circuit 7c is provided with a device, for example a grid 14, ensuring a withdrawal only in the liquid phase of the coolant 15, shown in Figures 2 and 3 under the form of a mixture of water and ice.

In accordance with FIG. 3, the downstream end 13a of each outlet conduit 13 of a bypass circuit 7 opens into the upper part of the intermediate circulation loop 2, so that the return of relatively hot water takes place directly in the ice of the two-phase mixture.

Furthermore, as shown in tanks 1c and 1g, a control system, for example 20c, is associated with each tank, and comprises a temperature detector (not shown), arranged on the heat exchanger 8, for example at its outlet , a flow adjustment member circulating in the bypass circuit, for example 7c, and an automatic means for controlling the same flow as a function of the temperature detected on the exchanger 8. The control system 20 can act or on the pump 11, or on one or other of the control valves 10 and 12.

• on établit dans le circuit 2 une boucle de circulation intermédiaire du fluide frigo-porteur, sous forme diphasique comme dit précédemment
• ce fluide est refroidi, et donc maintenu en permanence sous forme diphasique, en dehors de la boucle 2, avec production de glace dans le silo 50, par échange de chaleur avec le fluide frigorigène 21 circulant dans l'échangeur primaire 33
• au niveau de chaque cuve 1, dans le circuit de dérivation 7 correspondant, on dérive un courant en phase liquide du fluide frigo-porteur, on refroidit la charge dans la cuve 1 par échange de chaleur dans l'échangeur secondaire 8, avec le courant dérivé du fluide frigo-porteur ; cet échange de chaleur provoque le réchauffement de la phase liquide du courant dérivé ; et enfin on renvoie le courant réchauffé dans la boucle intermédiaire 2
• dans cette dernière, le courant dérivé renvoyé est immédiatement refroidi à la température de gel, par fusion de la phase solide présente à cet endroit dans la boucle intermédiaire.

Thanks to the installation described above, cold can be transferred to the various tanks 1a to 1h to be cooled, according to the following process:

• an intermediate circulation loop of the coolant fluid is established in circuit 2, in two-phase form as said above
• this fluid is cooled, and therefore permanently maintained in two-phase form, outside of loop 2, with production of ice in the silo 50, by heat exchange with the refrigerant 21 circulating in the primary exchanger 33
• at each tank 1, in the corresponding bypass circuit 7, a current in the liquid phase of the coolant is derived, the load in the tank 1 is cooled by heat exchange in the secondary exchanger 8, with the current derived from the coolant; this heat exchange causes the liquid phase of the bypass current to heat up; and finally we return the heated current in the intermediate loop 2
• in the latter, the diverted bypass stream is immediately cooled to the gel temperature, by melting the solid phase present at this location in the intermediate loop.

As shown in Figure 2, the current flowing in each bypass 7 associated with each tank 1 is taken from the liquid phase of the cooling fluid 15, that is to say from the water-ice mixture in sorbet.

And thanks to the control system 20 associated with each tank 1, the flow rate flowing in the branch 7 is controlled, for each enclosure or tank 1, as a function of one or more parameters measured or detected. The first parameter measured or detected is the temperature of the derivative current 7 reheated or being reheated in the exchanger 8. A second parameter can be the temperature in the tank 1. These two parameters make it possible to detect at any time the quantity of heat released in the tank, during the fermentation phase. By analyzing the evolution of any one of these temperatures, it is thus possible to detect the real need for cold of the tank, and to anticipate or modulate the refrigerating contribution to the latter.

• d'établir dans la descente vers le niveau inférieur 61, un courant de vitesse linéaire suffisamment importante pour entraîner avec lui la phase solide divisée du fluide frigo-porteur, par exemple les particules de glace
• et de conserver les particules de phase solide, au niveau où elles se trouvent, en cas d'arrêt de l'installation, en particulier en cas d'arrêt de la pompe de circulation 4.

According to the invention, an intermediate loop 2 for circulating the coolant fluid can be used according to any type of configuration. According to Figure 1, this configuration is located on one and the same level, so that the coolant fluid essentially flows in the same horizontal plane. However, in accordance with FIGS. 4 and 5, the intermediate circulation loop 2 can be arranged in two levels, one upper marked 60, and the other lower marked 61. In this case, the connection arrangements between these two levels, shown in Figures 4 and 5 allow:

• to establish in the descent to the lower level 61, a current of linear velocity large enough to carry with it the divided solid phase of the coolant, for example ice particles
• and to keep the solid phase particles, at the level where they are, in the event of the installation being stopped, in particular in the event of the circulation pump 4 being stopped.

For an intermediate circulation of the coolant fluid, with a low solid phase content, for example of the order of 10 to 15% of the volume in circulation, in accordance with FIG. 4, the descent to the lower level 61 is initiated, in top, by a siphon 62 mounted from bottom to top, and ends, below, by a siphon 63, normally mounted from top to bottom. The cross-section of the vertical internal conduit 64 of descent between the two siphons 62 and 63 is smaller than the nominal section of the loop 2 of intermediate circulation, so as to increase the linear speed of descent of the coolant. Thanks to this arrangement, the solid phase gradually accumulating at the top of the siphon 62, is pushed into the vertical duct or column, by entrainment with the liquid phase of the coolant, playing the role of a hunt. This same solid phase, in dispersed form, then passes the second siphon 63, and is found at the lower level 61. The arrangement according to FIG. 4 therefore proves to be effective in avoiding any obstruction obstructing the solid phase of the coolant.

The arrangement according to Figure 5 is used when the refrigerant fluid has in the intermediate loop 2 a relatively large content of ice, for example exceeding 10 to 15% of the total volume of the latter. According to this arrangement, the upper siphon 62 is deleted, but the lower siphon 63 retained. The descent to the lower level 61 is therefore initiated by a normal bend in the loop 2, at right angles. Downstream of the siphon 63, a pump 65 takes up part of the coolant fluid, only in liquid form, rises the flow rate thus withdrawn to the upper stage 60, and injects the flow flow back into an orifice 66 provided in the elbow 67, in the axis of the vertical descent conduit 64, the latter being at the nominal diameter of the circulation loop 2. In this way, an acceleration of the current of the coolant fluid, descending in the conduit 64, is created. According to the figure 5, if the installation is stopped, the entire solid phase of the coolant is found at the lower level 61, and remains there, taking account of the siphon 63. This thus avoids creating any significant plug or obstruction, at upper level 60 of loop 2, which would prevent restarting of the installation.

In accordance with FIG. 6, the outlet tap 13 of the bypass circuit is arranged upstream of the inlet tap 9 of the same circuit, according to the direction of circulation of the coolant fluid in the loop 2. A non-return valve 70 is disposed on the outlet 13 between the exchanger 8 and the return connection. This arrangement avoids any circulation of the coolant fluid, in the event of the pump 11 being stopped.

The present invention can be applied outside the field of winemaking, for example can be used in air conditioning or for cold stores.

Claims (10)

1. Cold transfer method in a plurality of recipients or enclosures (1) to be cooled, according to which there is established an intermediate circulation circuit (2) of a cold-bearing fluid (15) comprising two phases of same substance in melting equilibrium, the said fluid is cooled by heat exchange (33) with a refrigerating fluid (21) and, for each recipient or enclosure (1) to be cooled, there is tapped (7), from the intermediate circulation circuit, a partial current of the cold-bearing fluid, the environment to be cooled in the recipient or enclosure (1) is cooled by heat exchange (8) with the tapped partial current and the reheated partial current is returned (13) into the intermediate circulation circuit (2), according to which method the cooling power supplied by the refrigerating fluid (21), and the circulation flow rate in the circuit (2), are adjusted with respect to the total cooling power consumed in the plurality of recipients or enclosures (1) to be cooled, in such a way as to have available a cold-bearing fluid (15) in circulation, in a homogeneous mixture, and this taking place at least in the section of the circulation circuit in which the partial cooling currents are tapped, characterized in that, in combination:

   a) the diphasic cold-bearing fluid is cooled by indirect heat exchange with the refrigerating fluid,

   b) the intermediate circulation circuit consists in a free flowing loop (2) for carrying the cold-bearing fluid,

   c) each partial current is tapped (7), solely on the liquid phase of the cold-bearing fluid (15) in circulation in the loop and the reheated liquid partial current is returned (13) into the said loop.
2. Method according to Claim 1, characterized in that, in the direction of circulation of the cold-bearing fluid in the loop (2), each reheated partial liquid current is returned (13) immediately downstream or upstream of the tapping of the same current.
3. Method according to Claim 1, characterized in that, for each recipient or enclosure (1) to be cooled, the temperature of the tapped partial current (7) is detected, and the flow rate of the latter circulating in the tapping is controlled as a function of the detected temperature.
4. Cold transfer device in a plurality of recipients or enclosures (1) to be cooled, comprising an intermediate circulation circuit (2) for a cold-bearing fluid (15), a primary heat exchanger (33) between the cold-bearing fluid and a refrigerating fluid (21), and, associated with each recipient or enclosure (1), a tapped circuit (7) comprising a secondary heat exchanger (8) disposed in the recipient or enclosure (1), whose inlet (9) and outlet (13) are connected to the intermediate circulation circuit (2), characterized in that, in combination:

   a) the intermediate circulation circuit is a free-flowing loop (2) for carrying the cold-bearing fluid, in the diphasic state and in melting equilibrium in all parts of that loop

   b) the inlet (9) of each tapped circuit (7) is provided with a device (14) ensuring a tapping solely in the liquid phase of the cold-bearing fluid (15).
5. Device according to Claim 4, characterized in that, in the direction of circulation in the cold-bearing fluid in the loop (2), the outlet (13) of a tapped circuit is connected to the said loop immediately downstream or upstream of the inlet tapping (9) of the same tapped circuit.
6. Device according to Claim 4, characterized in that it comprises a tank (50) for the generation and storage of the cold-bearing fluid in melting equilibrium, connected by an inlet (53) to a tapping on the loop (2) carrying the said fluid, and by an outlet (51) with a feed of the said loop, the said tank being associated with the primary heat exchanger (33) between the cold-bearing fluid and the refrigerating fluid.
7. Device according to Claim 4, characterized in that the loop (2) is disposed on at least two different levels (60, 61), and a vertical duct (64), ensuring the carrying of the dispersed solid phase of the cold-bearing fluid, is disposed between the upper level (60) and the lower level (61).
8. Device according to Claim 7, characterized in that a lower syphon (63) is disposed at the foot of the vertical duct (64), between the latter and the lower level (61).
9. Device according to Claim 7, characterized in that an upper syphon (62), upward mounted, is disposed at the head of the vertical duct (64), and in that the latter has a smaller cross-section than the nominal cross-section of the loop (2).
10. Device according to Claim 8, characterized in that a circuit for the reinjection of the cold-bearing fluid, in that liquid phase, is disposed between a tapping downstream of the lower syphon (63), and a reinjection orifice (66), located' in a bend (67) between the upper level (60) and the vertical duct (64).

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