ES2818177T3 - Plate heat exchanger and reversible refrigeration machine, which includes said exchanger - Google Patents

Abstract

Plate heat exchanger (1100; 2100; 3100; 4100) that includes overlapping plates (2A-2L), which are inserted between two end plates (11, 12) and that define channels for the circulation of the heat exchange fluid , characterized in that the channels delimit the first circuit (C1) for the circulation of a first heat exchange fluid, which comprises a single passage, and a second circuit (C2, C'2, C3) for the circulation of a second fluid of heat exchange, which comprises two steps opposite each other, so that, for each direction of circulation of the second calorific fluid of the second circuit (C2, C'2, C3), one of the two steps of the second circuit (C2, C'2, C3) is countercurrent with respect to the passage of the first circuit (C1), while the other of the two passages of the second circuit (C2, C'2, C3) is countercurrent with respect to the passage of the first circuit (C1 ); characterized in that the second circuit comprises a first portion (C2) and a second portion (C'2), which are separated by an intermediate plate (13) of the exchanger and are connected to each other by a conduit (C3) outside the exchanger.

Description

DESCRIPTION

Plate heat exchanger and reversible refrigeration machine, which includes said exchanger

The present invention relates to a plate heat exchanger, as well as to a refrigeration machine including said exchanger.

Figure 1 shows a welded plate heat exchanger 100, provided with a set of overlapping plates 2A, 2B and 2C. Each plate 2A, 2B and 2C has its opposite surfaces corrugated according to a precise scheme, for example a chevron profile. The edges of the plates are provided with gaskets to prevent liquid leakage. Plates 2A, 2B and 2C are arranged against each other, between two end plates 11 and 12, so that the corrugated surfaces of two adjacent plates together define channels 20 for the circulation of heat exchange fluids.

Each plate 2A, 2B and 2C and each end plate 11 and 12 comprises four openings, each one produced in one of its corners, namely, a first opening 21 which is used as an E1 inlet for a first heat exchange fluid, a second opening 22 that is used as outlet S1 for the first heat exchange fluid, a third opening 23 that is used as inlet E2 for a second heat exchange fluid and a fourth port 24 that is used as outlet S2 for the second fluid heat exchange. Channels 20 defined against each corrugated surface receive the first or second heat exchange fluid. In the example of figure 1, the first heat exchange fluid circulates in a first circuit between the second and third plates 2B and 2C. The second heat exchange fluid circulates in a second circuit that extends between the plates 2A and 2b. In this way, the first and second heat exchange fluids alternately circulate between two adjacent plates 2A, 2B and 2C to ensure a transfer of thermal energy between the fluids.

Figure 2 shows a reversible refrigeration machine that includes a compressor 400, a pressure reducing valve 200 and two exchangers 100 and 300 similar to the exchanger of Figure 1. These four elements are mounted in a common refrigerant fluid circuit C. The exchangers 100 and 300 function alternatively as condenser or evaporator, depending on whether the refrigeration machine works in heating mode or in air conditioning mode. The mode change occurs by changing the direction of circulation of the refrigerant fluid in the common circuit C.

The first exchanger 100 implements a heat transfer between the common circuit C and a first exchange circuit C10. The second exchanger 300 implements a heat transfer between the common circuit C and a second exchange circuit C20.

For each operating mode, for example, one of the exchangers 100 and 300 works in countercurrent with respect to the exchange circuit C10 or C20, which interacts with this exchanger, while the other exchanger works in cocurrent with respect to the other circuit of C10 or C20 exchange.

The performance of a plate heat exchanger is better in countercurrent than in cocurrent so that, for each operating mode, one of the exchangers 100 and 300 does not have an optimized performance.

Document DE 10 2006 002 018 describes a reversible refrigeration machine that allows changing the operating mode without reversing the direction of circulation of the refrigerant fluid, using a three-way valve installed in the refrigeration circuit. This solution is complex to implement, since it requires the installation of a device to distribute the refrigerant fluid.

JP H10288480 A shows a plate type heat exchanger suitable for heat exchange between two fluids of different types. A plurality of heat transfer plates are laminated at a constant interval. The first to fourth openings correspond to the inlet pipe and the outlet pipe for refrigerant and water are made at the four corners of the heat transfer plates. A seal member is applied around a specific opening. The cooling channels, the first water channels, and the second water channels are repeatedly formed between the respective heat transfer plates.

JP 2008 000636 A shows a plate type apparatus for producing fresh water provided with a heater for heating raw seawater using hot water to produce steam, a condenser for cooling the steam produced using cooling water to produce distilled water, and a preheating means for heating a part of the cooling water discharged from the condenser and introducing the heated cooling water into the heater as raw seawater.

These are the disadvantages that the invention aims to remedy more particularly by proposing a new plate exchanger that is easy to use in a reversible refrigeration machine and that has a satisfactory performance.

To this end, the invention relates to a plate heat exchanger according to claim 1.

According to advantageous but not mandatory aspects of the invention, such an exchanger can incorporate one or more of the following characteristics, considered in any technically acceptable combination:

the first circuit comprises several intermediate branches, each one delimited between two adjacent plates and connecting to each other in parallel a forward branch and a return branch of the first circuit; the second circuit comprises two adjacent zones, in which the intermediate branches of the second circuit belong, for one of these zones, to one of the two passes of the second circuit and, for the other zone, to the other of the two passes of the second circuit;

The exchanger includes a tube that is provided with a slot that distributes the second heat exchange fluid in several channels of the second circuit.

Another aspect of the invention refers to a reversible refrigeration machine that includes a common refrigerant fluid circuit, in which a compressor, a pressure reducing valve and two exchangers are arranged, each of which has been defined above.

According to advantageous, but not mandatory, aspects of the invention, such a refrigerating machine can incorporate one or more of the following characteristics, considered in any technically acceptable combination:

the refrigeration machine comprises a four-way valve capable of changing the direction of circulation of the refrigerant fluid in the common circuit;

the common circuit is formed by the second circuit of the exchangers;

the second circuit comprises an inlet and an outlet arranged in the upper part of the exchangers; the second circuit comprises an inlet and an outlet arranged in the lower part of the exchangers. The invention will be better understood, and other advantages of said invention will become clearer in light of the following description of a plate exchanger according to the invention, which is provided only as an example and with reference to the drawings in which:

Figure 1 is an exploded perspective view of a prior art plate exchanger;

Figure 2 is a schematic view of a prior art reversible refrigeration machine;

Figure 3 is an exploded schematic view of an exchanger according to a first embodiment of the invention;

Figures 4 and 5 are diagrams of the exchanger of Figure 3 with a first and a second flow direction, respectively, of the heat exchange fluids;

Figures 6 and 7 are diagrams of refrigeration machines including the exchanger of Figure 3;

Figure 8 is a diagram of the exchanger of Figure 3 according to another orientation;

Figure 9 is an exploded perspective view of an exchanger according to a second embodiment of the invention;

Figures 10 and 11 are diagrams of the exchanger of Figure 9 with a first and a second flow direction, respectively, of the heat exchange fluids;

Figures 12 and 13 are diagrams of a tube for dispensing fluid;

Figures 14 to 17 are diagrams of an exchanger according to a third embodiment of the invention, with different directions of circulation of the heat exchange fluids;

Figures 18 to 21 are diagrams of an exchanger according to a fourth embodiment of the invention, with different directions of circulation of the heat exchange fluids; Y

Figures 22 and 23 are diagrams of the tube of Figures 12 and 13, positioned for an exchanger in one of the configurations of Figures 14, 15, 18 and 19 and for one of the configurations of Figures 16, 17, 20 and 21, respectively.

Figures 3-8 and 18-21 do not fall within the scope of claim 1.

Figure 3 shows a plate exchanger 1100. It includes a first end plate 11 that defines a first outer surface A of exchanger 1100, and a second end plate 12 that defines a second outer surface B of exchanger 1100 opposite the first surface A.

Twelve plates 2A to 2L are superimposed, that is, arranged successively, one against the other, between the terminal plates 11 and 12. The plate 2K is arranged against the first terminal plate 11, and the plate 2L is arranged against the second terminal plate 12.

End plates 11 and 12 and plates 2A to 2L have a generally rectangular shape. The exchanger 1100 has a general parallelepiped shape with a rectangular base. M is used to designate an upper edge of exchanger 1100 located at the top of Figure 3, and N is used to designate a lower edge of exchanger 1100 parallel to the upper edge M and located at the bottom of Figure 3. The Edges M and N are short in length and connect the long edges O and P of end plates 11 and 12 and plates 2A to 2L, which are perpendicular to the short edges M and N. The long edge O is in the foreground of Figure 3 and the long edge P in the background.

Each plate 2A to 2L comprises two opposite rectangular surfaces that are corrugated according to a precise scheme that does not limit the invention, for example, a chevron profile. These undulations are not represented in figure 3; they may be similar to those of the exchanger of figure 1. The M, N, O and P edges of the plates 2A to 2L are provided with welded joints, not shown, to prevent fluid leaks. The mutually oriented corrugated surfaces of two adjacent plates 2A to 2L together define channels for the turbulent circulation of heat exchange fluids. These channels are not shown in Figure 3, but are possibly similar to channels 20 in Figure 1.

In the direction of its thickness, the exchanger 1100 comprises a first zone Z1, between the first end plate 11 and the plate 2E, and a second zone Z2, between the plate 2F and the second end plate 12. The zones Z1 and Z2 are contiguous. The first zone Z1 is located on the side of the first surface A of the exchanger 1100, and the second zone Z2 is located on the side of the second surface B. The zones Z1 and Z2 divide the exchanger 1100 in two in their thickness, that is that is, in a direction perpendicular to end plates 11 and 12 and plates 2A to 2L.

The exchanger 1100 delimits two heat exchange fluid circuits C1 and C2. For use in a refrigeration machine, the first circuit C1 is provided for water and the second circuit C2 for a refrigerant fluid. The first circuit C1 corresponds to one of the exchange circuits C10 or C20 of the refrigeration machine of figure 2, and the second circuit C2 corresponds to the common circuit C.

The circuits C1 and C2 are defined so that the water circuit C1 comprises a single pass, that is, the fluid circulates between the edges N and M in a single direction, specifically from the bottom to the top in the example of the Figure 3. The refrigerant fluid circuit C2 comprises two passages, specifically an inlet passage in the zone Z2, where the refrigerant fluid circulates in a first direction, specifically from the bottom to the top between the edges N and M, and a outlet passage in zone Z1, where the refrigerant fluid circulates in a second direction opposite to the first, that is, from top to bottom between edges M and N.

This configuration results from the particular arrangement of the corrugations of the plates 2A to 2L and of the holes 21 to 24 produced in the corners of the end plates 11 and 12 and of the plates 2A to 2L as described below. Terminal plates 11 and 12 and plates 2A to 2L are each provided with a number of holes between one and four in order to guide the flow of fluids in circuits C1 and C2.

The hole 21 is located in a first lower corner, at the junction between the N and P edges. The hole 22 is located in a second lower corner, at the junction between the N and O edges. The hole 23 is located in a first upper corner, at the junction between the M and P edges. Hole 24 is located in a second upper corner, at the junction between the M and O edges.

For a first direction of flow of fluids in circuits C1 and C2, as defined in figure 3, an inlet E1 of the first circuit C1 is formed by a first hole 21 of the second terminal plate 12, in the zone Z2. The first circuit C1 comprises a first lower branch or front branch C11 in which the fluid flows to the plate 2K, through the holes 21 that are drilled in each plate 2A to 2J and 2L. The first terminal plate 11 and the plate 2K have no hole 21. A second upper branch or return branch C12 of the first circuit C1 is defined between the plate 2K and a hole 23 of the second terminal plate 12, which defines an outlet S1 of the first circuit C1 in the second zone Z2. The first end plate 11 and plate 2K have no hole 23. Between plates 2K and 2L, fluid flows through holes 23 drilled in each plate 2A to 2J and 2L.

Between branches C11 and C12, the first circuit C1 comprises several intermediate branches C13 to C18 connected in parallel between branches C11 and C12. The intermediate branches C13 to C18 are represented rectilinear in the diagram of Figure 3 but, in practice, they meander in the pattern defined by the corrugations of the plates 2A to 2L.

Branches C13 to C15 are part of the second zone Z2, and branches C16 to C18 are part of the first zone Z1.

Thus, in zones Z1 and Z2, the first circuit C1 has a single pass from edge N and towards edge M. In other words, between edges N and M and for the two zones Z1 and Z2, the fluid it circulates in the first circuit C1 in only one direction, that is, from the bottom up.

The rest of the description refers to the second circuit C2. An input E2 of the second circuit C2 is formed by a hole 22 of the second terminal plate 12, in the second zone Z2. The second circuit C2 comprises a first lower branch C21, which extends exclusively in the second zone Z2 and which connects the second input E2 with a first and a second intermediate branch C22 and C23 connected in parallel between the lower branch C21 and an upper branch C24. In the intermediate branches C22 and C23, the fluid flows from bottom to top, from edge N to edge M. Plates 2F and 2G do not have orifice 22.

The upper branch C24 extends through the holes 24 drilled in the plates 2B to 21 in the zones Z1 and Z2, and is connected to two other intermediate branches C25 and C26 in which the fluid flows from above to below, from the edge M to edge N. The intermediate branches C25 and C26 connect the upper branch C24 in parallel to a second lower branch C27, which extends exclusively in the first zone Z1, through the holes 22 drilled in the plates 2A to 2C , 2K and in the first terminal plate 11, up to an output S2 of the second circuit C2 formed by the hole 22 of the terminal plate 11, in the first zone Z1. Thus, in zone Z2, the second circuit C2 has an inlet passage where the fluid circulates in a first direction, specifically from the lower edge N and towards the upper edge M. In zone Z1, the second circuit C2 has an outlet passage where the fluid flows in a second direction opposite to the first direction, that is, from the upper edge M and towards the lower edge N.

Figures 4 and 5, more schematically, show again the arrangement of circuits C1 and C2 of exchanger 1100. Figure 4 corresponds to the first flow direction of Figure 3 for circuit C2, and Figure 5 to a second opposite direction of travel.

The first flow direction of Figures 3 and 4 corresponds to a first mode of operation, in which the exchanger 1100 operates by evaporation. In the second zone Z2, the refrigerant fluid of the circuit C2 performs a first step that is down-current with respect to the water of the circuit C1 (circulates from the bottom up between the edges N and M) and, in the first zone Z1, the refrigerant fluid of the circuit C2 performs a second step that is countercurrent with respect to the water of the circuit C1 (circulates from top to bottom between the edges M and N).

In Figure 5, the direction of circulation of the refrigerant fluid in the second circuit C2 is reversed. The direction of water circulation in circuit C1 remains unchanged. The E2 input of the C2 circuit becomes the S2 output and vice versa. The exchanger 1100 then operates in a second mode, by condensation.

In this second mode, for the first zone Z1, the cooling fluid in the second circuit C2 performs a first step that is equicurrent with respect to the water of the first circuit C1, (it circulates from bottom to top from the lower edge N towards the upper edge M) and, in the second zone Z2, the cooling fluid in the second circuit C2 performs a second step that is countercurrent with respect to the water of the first circuit C1 (it circulates from top to bottom from the upper edge M to the lower edge N) .

In this way, for each operating mode, the exchanger 1100 makes it possible for the cooling fluid of the circuit C2 to carry out a first pass that is countercurrent and a second pass that is countercurrent with respect to the water of the circuit C1. In this way, the thermal efficiency of the exchanger 1100 is improved since, in each operating mode, the fluids of the circuits C1 and C2 circulate in countercurrent through the area corresponding to the outlet passage of the circuit C2.

Figures 6 and 7 show a reversible refrigeration machine that includes a compressor 400, a pressure reducing valve 200 and two exchangers 1100 and 1200, each similar to the exchanger of Figures 3 to 5. These four elements 400, 200, 1100 and 1200 are mounted in a common refrigerant fluid circuit C.

The first exchanger 1100 implements a heat transfer between the common circuit C and a first exchange circuit C10. The second exchanger 1200 implements a heat transfer between the common circuit C and a second exchange circuit C20.

The 1100 and 1200 exchangers function alternately as condenser or evaporator depending on whether the refrigeration machine works in heating mode or in air conditioning mode. The mode change occurs by changing the direction of circulation of the refrigerant fluid in the common circuit C using a four-way valve V1.

In Figure 6, for the first mode of operation, the exchanger 1100 operates by condensation, and the second exchanger operates by evaporation. Valve V1 is in a first position. The refrigerant fluid of the common circuit C circulates in a first direction. The first exchange circuit C10 is a hot water circuit, and the second exchange circuit C20 is a cold water circuit.

In Figure 7, for the second mode of operation, the exchanger 1100 operates by evaporation, and the second exchanger operates by condensation. Valve V1 is in a second position. The refrigerant fluid of the common circuit C circulates in a second direction opposite from the first direction of figure 6. The first exchange circuit C10 is a cold water circuit, and the second exchange circuit C20 is a hot water circuit.

For each operating mode, each of the exchangers 1100 and 1200 works, for one of the zones Z1 and Z2, countercurrent, while for the other zone Z2 or Z1, the exchangers 1100 and 1200 work in cocurrent.

More precisely, in the first operating mode represented in figure 6, and for each exchanger 1100 and 1200, the first step or input step of the common circuit C in the zone Z2 is carried out in a down-current manner with respect to the corresponding exchange circuit C10 or C20, and the second step or output step of the common circuit C in the zone Z1 is carried out countercurrently with respect to the corresponding exchange circuit C10 or C20. This configuration corresponds to that of figure 4.

In the second operating mode represented in figure 7 and for each exchanger 1100 and 1200, the first step or input step of the common circuit C in the zone Z1 is carried out in a down-current manner with respect to the corresponding exchange circuit C10 or C20, and the second step or exit step of the common circuit C in the zone Z2 is carried out countercurrently with respect to the corresponding exchange circuit C10 or C20. This configuration corresponds to that of figure 5.

In Figures 3 to 7, the exchanger 1100 is arranged according to a first orientation, in which the inputs E1 and E2 of the circuits C1 and C2 are arranged in the lower part of the exchanger 1100, along the lower edge N. The fluid in circuit C1, in the two zones Z1 and Z2, and fluid in circuit C2, in zone Z2 for the configuration of figure 4, and in zone Z1 for the configuration of figure 5, circulate in an upward direction, against the force exerted by gravity.

Figure 8 shows the exchanger 1100 in a second orientation, in which the edge M is oriented towards the bottom, while the edge N is oriented towards the top. The inputs E1 and E2 of circuits C1 and C2 are arranged in the upper part of exchanger 1100, along the upper edge M. The fluid in circuit C1, in the two zones Z1 and Z2, and the fluid in circuit C2, in zone Z1, they circulate downward in the direction of the force exerted by gravity.

For the two orientations of the exchanger 1100, the flow of the water in the circuit C1 is countercurrent with respect to the flow of the cooling fluid in the outlet passage of the circuit C2, that is, the flow of the water is directed upwards when the inlet E2 and output S2 is at the bottom, as shown in Figures 4-7, and is directed downward when input E2 and output S2 are at the top, as shown in Figure 8.

Figure 9 shows an exchanger 2100 according to a second embodiment of the invention, of the double-circuit exchanger type. Elements of exchanger 2100 similar to those of exchanger 1100 bear the same reference numerals. In the following, elements of exchanger 2100 that are similar to those of exchanger 1100 are not described in detail.

As described below and unlike exchanger 1100, exchanger 2100 comprises two independent refrigerant fluid circuits C2 and C'2, which can implement two steps when properly connected to each other through a conduit C3 represented with dotted lines on the Figure 9. Duct C3 is schematically represented in Figures 10 and 11, which are described in greater detail below.

Exchanger 2100 comprises two end plates 11 and 12 and eight corrugated plates 2A to 2H arranged between end plates 11 and 12. Exchanger 2100 also has an intermediate end plate 13 inserted between plates 2D and 2E. The intermediate end plate 13 materially delimits the separation between the zones Z1 and Z2.

The exchanger 2100 has a generally rectangular shape and consists of an upper edge M, a lower edge N, and two side edges O and P. End plates 11, 12 and 13 and plates 2A to 2H are provided with holes 21, 22, 23 and / or 24.

The first circuit C1 provided, for example, for water in the case in which a refrigeration machine is used, comprises an inlet E1 implemented by a hole 24 produced in the terminal plate 11. The first circuit C1 comprises a first branch or front branch C11 starting from input E1 and passing through holes 24 produced in boards 2A to 2G, as well as intermediate terminal board 13. A second lower branch or return branch C12 of the first circuit begins at output S1 and passes through holes 22 produced in plates 2A to 2G, as well as intermediate end plate 13. Between end plate 11 and plate 2H, fluid flows through holes 22 drilled in each plate 2A to 2G .

Between branches C11 and C12, the first circuit C1 comprises several intermediate branches C13 to C16 connected in parallel between branches C11 and C12. The intermediate branches C13 to C16 are represented rectilinear in the diagram of Figure 9 but, in practice, they meander in the pattern defined by the corrugations of the plates 2A to 2H.

Branches C13 to C14 are part of the first zone Z1, and branches C15 to C16 are part of the second zone Z2.

Thus, in the zones Z1 and Z2, the first circuit C1 has a single step, from the upper edge M and towards the lower edge N. In other words, between the edges M and N and for the two zones Z1 and Z2 , the fluid circulates in the first circuit C1 in a single direction, specifically from top to bottom.

The rest of the description refers to the circuits C2 and C'2 of the refrigerant fluid.

The circuit C2 comprises an input E20 formed by a hole 23 produced in the terminal plate 12. A first upper branch C21 or front branch of the circuit C2 extends from the input E20 and the plate 2F, in the second zone Z2, through holes 23 produced in plates 2G and 2H.

The circuit C2 has an outlet S20 formed by a hole 21 produced in the terminal plate 12. A second lower branch C22 or return branch of the circuit C2 extends between the outlet S20 and the plate 2F, in the second zone Z2, through of holes 21 produced in plates 2G and 2H.

Branches C21 and C22 are connected to each other by an intermediate branch C23 which is delimited between plates 2F and 2G.

Circuit C'2 comprises an input E'20 formed by a hole 21 produced in terminal board 11. A first lower branch C'21 or front branch of circuit C'2 extends between input E'20 and plate 2C , in the first zone Z1, through the holes 21 produced in the plates 2A and 2B.

The circuit C'2 an outlet S'20 formed by a hole 23 produced in the terminal plate 11. A second upper branch C'22 or return branch of the circuit C'2 extends between the outlet S'20 and the plate 2C , in the first zone Z1, through the holes 23 produced in the plates 2A and 2B.

Branches C'21 and C'22 are connected to each other by an intermediate branch C'23 which is delimited between plates 2B and 2C.

In figure 10, the refrigerant fluid of circuits C2 and C'2 circulates in a first direction, and the connection between circuits C2 and C'2 is implemented by means of a connection conduit C3, which connects the outlet S20 of the circuit C2 with input E'20 of circuit C'2. In this way, the outlet S'20 of the exchanger 2100, as shown in Figure 9, becomes the outlet S2 of the common heat exchange fluid circuit formed by the combination of the circuits C2 and C'2. The E20 input becomes the E2 input of the common circuit C2 and C'2.

In zones Z1 and Z2, the first circuit C1 has a single pass, from edge M to edge N. In other words, between edges M and N and for the two zones Z1 and Z2, the fluid circulates in the first circuit C1 in a single direction, specifically from top to bottom.

In the direction of circulation of the fluid of figure 10, the second circuit C2 and C'2 comprises a first step or advance step in the zone Z2, where the fluid circulates in a cocurrent way in the circuit C2, and a second step or return passage in zone Z1, where the fluid circulates countercurrently in circuit C'2.

In Figure 11, the direction of fluid flow in circuits C2 and C'2 is reversed. The input E2 is in the zone Z1 at the beginning of the circuit C'2, and the output S2 is in the zone Z2, at the output of the circuit C2.

In the direction of circulation of the fluid of figure 11, the second circuit C2 and C'2 comprises a first step or advance passage in the zone Z1, where the fluid circulates in a cocurrent way in the circuit C'2, and a second passage or return passage in zone Z2, where the fluid circulates countercurrently in circuit C2.

In this way, regardless of the direction of flow of the fluid in the circuit C2 and C'2, the exchanger 2100 comprises a passage that is countercurrent and a passage that is countercurrent, which makes it possible to optimize the heat exchanges.

Two exchangers similar to exchanger 2100 and provided with conduit C3 can be used in a reversible refrigeration machine, in a similar way to exchanger 1100, as implemented in figures 6 and 7. For the two directions of fluid circulation in the common circuit C Each exchanger comprises two passages, specifically the outlet passage which is countercurrent and the input passage which is countercurrent, which promotes heat exchanges regardless of the direction of circulation.

The machine can be a water-water refrigeration machine in which the fluids that the 2100 exchangers cool and heat are water.

It is also possible to use an air-water refrigeration machine that includes a first air-fluid exchanger, also called a "coil", and a second two-pass exchanger, such as exchanger 2100.

Figures 12 and 13 represent a tube 500 incorporated in exchangers 3100 and 4100 shown in Figures 14 to 21.

The tube 500 is provided with a longitudinal slot 501 of width L. The slot 501 ensures the distribution of the fluid in the circuits C'2 of the zone Z2 of the exchangers 3100 and 4100 when they work by evaporation. The slot 501 extends over most of the tube 500, the slot being interrupted at its ends to ensure rigidity of the tube. In service, slot 501 is oriented vertically toward the bottom of the tube.

The exchanger 3100 is, in general, similar to the exchanger 2100. It is provided with a connection conduit C3 that connects two circuits C2 and C'2 to each other. Circuit C2 comprises a single channel in zone Z1, while circuit C'2 comprises three channels in zone Z2. The tube 501 distributes the fluid in the channels of the circuit C'2 of the second zone Z2 when the exchanger works by evaporation.

The path of the refrigerant fluid in circuits C2 and C'2, referring to figure 14, is as follows for evaporative operation: the fluid enters the channel of circuit C2 through an inlet E2 located at the lower end N of exchanger 3100. The fluid rises through this channel and joins conduit C3, passing through an outlet S'2 of circuit C2. The fluid circulates through the conduit C3 and enters the tube 501 through an inlet E'2 located at the upper end M of the exchanger 3100. The slot 51 distributes the fluid in the three channels of the circuit C'2. At the lower end N, on the side opposite the tube 501, the three channels are connected to an outlet S2 of the exchanger 3100. The detail of the fluid path in the three channels of the circuit C'2 is indicated in figure 22.

The path of the refrigerant fluid in circuits C2 and C'2, referring to figure 15, is as follows for condensation operation in the opposite direction to evaporation operation: the fluid enters the channels of circuit C'2 through from an inlet S2 located at the lower end N of the exchanger 3100. The fluid rises through these channels, enters the tube 500 through the slot 501 and joins the conduit C3, passing through an outlet E'2 of the circuit C ' two. The fluid circulates in conduit C3 and enters circuit C2 through an inlet S'2. At the lower end N, circuit C2 is connected to an outlet E2 of exchanger 3100.

In terms of heat exchanges, the double-pass exchanger 3100 achieves optimum performance when there are two to four times more channels in the outlet passage of circuit C'2 than in the inlet passage of circuit C2.

Figure 16 shows exchanger 3100 with inlet E2 and outlet S2 of circuit C2 at the top for evaporative operation. Figure 17 shows exchanger 3100 with input S2 and output ^e 2 of circuit C2 at the top for condensation operation. There are two to four times more channels in the output stage of circuit C'2 than there are in the input stage of circuit C2. Figures 18 and 19 show the exchanger 4100 respectively for evaporative and condensation operations with the inlet and outlet of circuits C2 and C'2 at the bottom. Figures 20 and 21 show the exchanger 4100 respectively for evaporative and condensation operations with the inlet and outlet of circuits C2 and C'2 at the top. The exchanger differs from exchanger 3100 in that it does not incorporate conduit C3. The operation of exchanger 4100 is similar to that of exchanger 3100.

Figure 22 shows the path of the fluid in a channel of the zone Z2 of the exchanger of Figure 14 or of the exchanger of Figure 18, which operates by evaporation, with the slot 501 of tube 500 oriented vertically downwards.

Figure 23 shows the path of the fluid in a channel of the zone Z2 of the exchanger of Figure 16 or of the exchanger of Figure 20, which operates by evaporation, with the slot 501 of the tube 500 oriented vertically downwards.

Claims (9)

1. Plate heat exchanger (1100; 2100; 3100; 4100) that includes overlapping plates (2A-2L), which are inserted between two end plates (11, 12) and that define channels for the circulation of the exchange fluid heat, characterized in that the channels delimit the first circuit (C1) for the circulation of a first heat exchange fluid, comprising a single passage, and a second circuit (C2, C'2, C3) for the circulation of a second heat exchange fluid, which comprises two opposite steps, so that, for each direction of circulation of the second calorific fluid of the second circuit (C2, C'2, C3), one of the two steps of the second circuit (C2, C'2, C3) is down-current with respect to the passage of the first circuit (C1), while the other of the two steps of the second circuit (C2, C'2, C3) is countercurrent with respect to the step of the first circuit (C1); characterized because The second circuit comprises a first portion (C2) and a second portion (C'2), which are separated by an intermediate plate (13) of the exchanger and are connected to each other by a conduit (C3) outside the exchanger. Plate heat exchanger (1100) according to claim 1, characterized in that the first circuit (C1) comprises several intermediate branches (C13-C18) each delimited between two adjacent plates (2A-2L) and connecting to each other in parallel a forward branch (C11) and a return branch (C12) of the first circuit (C1). Plate heat exchanger (1100) according to claim 1, characterized in that the second circuit (C2) comprises two adjacent zones (Z1, Z2), in which the intermediate branches (C23-C26) of the second circuit (C2) they belong, for one of these zones, to one of the two steps of the second circuit, and for the other zone, to the other of the two steps of the second circuit. Plate heat exchanger (3100; 4100) according to any of the preceding claims, characterized in that the exchanger includes a tube (500) that is provided with a slot (501) that distributes the second heat exchange fluid in several channels of the second circuit (C'2). 5. Reversible refrigeration machine that includes a common refrigerant fluid circuit (C) in which a compressor (400), a pressure reducing valve (200) and two exchangers (1100; 2100; 3100; 4100) are arranged, each one of which is in accordance with any of the preceding claims. Refrigerating machine according to claim 5, characterized in that it comprises a four-way valve (V1) capable of changing the direction of circulation of the refrigerant fluid in the common circuit (C). Refrigerating machine according to claim 5 or 6, characterized in that the common circuit (C) is formed by the second circuit (C2, C'2, C3) of the exchangers (1100; 2100; 3100; 4100). Refrigerating machine according to any of claims 5 to 7, characterized in that the second circuit (C2, C'2, C3) comprises an inlet (E2) and an outlet (S2) arranged in the upper part of the exchangers. Refrigerating machine according to any of claims 5 to 7, characterized in that the second circuit (C2, C'2, C3) comprises an inlet (E2) and an outlet (S2) arranged in the lower part of the exchangers.