EXCHANGER SYSTEM COMPRISING TWO HEAT EXCHANGERS

Abstract

An exchanger system comprising two heat exchangers, a bypass line which extends between an inlet and an outlet, a line connected between the bypass line and a first orifice of each heat exchanger, a return line connected to two second orifices of the two heat exchangers and to the bypass line, three valves, and a controller which commands each valve alternately to open or to close. With such an arrangement, the intensities of the pressure peaks due to plugs are limited by distribution of the flow of the heat-transfer fluid in two parallel lines.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the French patent application No. 2001461 filed on Feb. 14, 2020, the entire disclosures of which are incorporated herein by way of reference.

FIELD OF THE INVENTION

The present invention relates to an exchanger system which allows calories to be exchanged between two fluids and which comprises two heat exchangers and a set of valves.

BACKGROUND OF THE INVENTION

To cool certain installations, it is known practice to use an exchanger system which comprises a heat exchanger in which a heat-transfer fluid such as oil circulates and which is placed in an air stream to cool the heat-transfer fluid. The heat-transfer fluid is circulated, for example, by a pump.

The heat exchanger comprises a network of channels which extends between an inlet and an outlet and in which the heat-transfer fluid circulates.

The exchanger system also comprises a line which extends out of the heat exchanger and which passes through the installation to be cooled.

By circulating in the line and by passing through the installation, the heat-transfer fluid is charged with calories, and by passing through the heat exchanger, the heat-transfer fluid discharges its calories into the air.

The exchanger system generally comprises a bypass circuit with a bypass line between the inlet and the outlet and a bypass valve on the bypass line. The bypass valve can be alternately opened or closed.

When the bypass valve is closed, the heat-transfer fluid does not flow through the bypass line and passes through the heat exchanger to ensure the cooling.

When the bypass valve is open, the heat-transfer fluid flows through the bypass line and does not pass through the heat exchanger.

While such an installation gives satisfaction, in some cases air may happen to be found in the heat-transfer fluid and, when the bypass valve is opened, the air builds up in the high point of the heat exchanger, thus creating a hydraulic plug. When the bypass valve is then closed, the heat-transfer fluid resumes circulating in the heat exchanger and encounters this hydraulic plug which will take a certain time to be cleared before the heat-transfer fluid can once again circulate normally in the heat exchanger. The encounter with the plug will cause the occurrence of a pressure peak on the supply line.

It is therefore necessary to find an exchanger system which limits the intensities of the pressure peaks due to the hydraulic plugs in the heat exchanger.

SUMMARY OF THE INVENTION

One object of the present invention is to propose an exchanger system which comprises two heat exchangers and a set of valves in which each is controlled alternately to open or close, depending on the conditions of use.

To this end, there is proposed an exchanger system containing a heat-transfer fluid and comprising:

• • a first heat exchanger and a second heat exchanger, in which each exchanger comprises a first orifice and a second orifice,
  • a bypass line which extends between an inlet and an outlet,
  • a first line fluidically connected between the bypass line and the first orifice of the first heat exchanger between the inlet and the outlet of the bypass line,
  • a second line fluidically connected between the bypass line and the first orifice of the second heat exchanger between the first line and the outlet of the bypass line,
  • a return line fluidically connected to the two second orifices of the two heat exchangers and to the bypass line between the second line and the outlet of the bypass line,
  • a first valve mounted on the bypass line between the first line and the second line,
  • a second valve mounted on the bypass line between the second line and the return line,
  • a third valve mounted on the return line between the two second orifices and the bypass line, and
  • a control unit which commands each valve alternately to open or to close.

With such an arrangement, the intensities of the pressure peaks due to plugs are limited by the distribution of the flow of the heat-transfer fluid in two parallel lines.

Advantageously, from an open position of the first valve, from an open position of the second valve, and from a closed position of the third valve, the control unit is designed to command the opening of the third valve and the closing of the second valve.

Advantageously, from the state thus reached, the control unit is designed to command the closing of the first valve, the opening of the second valve and the closing of the third valve.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention mentioned above, and others, will become more clearly apparent on reading the following description of an exemplary embodiment, the description being given in relation to the attached drawings, in which:

FIG. 1 is a schematic representation of an exchanger system according to the invention according to a first condition of use,

FIG. 2 is a schematic representation of an exchanger system according to the invention according to a second condition of use, and

FIG. 3 is a schematic representation of an exchanger system according to the invention according to a third condition of use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 3 show an assembly 20 which comprises an installation 10 and an exchanger system 100 according to the invention which is designed to cool the installation 10.

The exchanger system 100 comprises a first heat exchanger 102a and a second heat exchanger 102b.

The exchanger system 100 comprises a bypass line 104 which extends between an inlet 106a and an outlet 106b.

Each heat exchanger 102a-b comprises a first orifice 108a-b and a second orifice 110a-b. As described below, an orifice 108a-b, 110a-b can, depending on the modes of operation, be an inlet or an outlet.

The exchanger system 100 also comprises a first line 112a fluidically connected between the bypass line 104 and the first orifice 108a of the first heat exchanger 102a. The connection to the bypass line 104 is made between the inlet 106a and the outlet 106b of the bypass line 104.

The exchanger system 100 also comprises a second line 112b fluidically connected between the bypass line 104 and the first orifice 108b of the second heat exchanger 102b. The connection to the bypass line 104 is made between the first line 112a and the outlet 106b of the bypass line 104.

The exchanger system 100 also comprises a return line 114 which is fluidically connected to the two second orifices 110a-b of the two heat exchangers 102a-b and to the bypass line 104. The connection to the bypass line 104 is made between the second line 112b and the outlet 106b of the bypass line 104.

The exchanger system 100 also comprises a first valve 116a which is mounted on the bypass line 104 between the first line 112a and the second line 112b.

The exchanger system 100 also comprises a second valve 116b which is mounted on the bypass line 104 between the second line 112b and the return line 114.

The exchanger system 100 also comprises a third valve 116c which is mounted on the return line 114 between the two second orifices 110a-b and the bypass line 104.

Each valve 116a-c is commanded alternately to open or to close by a control unit, for example of processor type, which controls the position of each valve 116a-c according to the needs of the exchanger system 100. The control unit can be internal to the exchanger system 100 or it can be a more general control unit for controlling the assembly 20.

The assembly 20 also comprises a transfer line 22 which extends between the outlet 106b and the inlet 106a of the bypass line 104 by passing through the installation 10.

A heat-transfer fluid, such as oil for example, circulates in the transfer line 22 and the exchanger system 100 via a pump 30 mounted, for example, on the transfer line 22. By passing through the installation 10, the heat-transfer fluid is charged with calories.

Thus, the oil is driven in the transfer line 22 then, depending on the position of the valves 116a-c, the oil will circulate between the inlet 106a and the outlet 106b of the bypass line 104 and, in particular, possibly, in the heat exchangers 102a-b.

The heat exchangers 102a-b are disposed in an air stream F which allows calories to be discharged from the heat-transfer fluid to the air.

In the mode of operation of FIG. 1, the first valve 116a is closed, the second valve 116b is open and the third valve 116c is closed.

The heat-transfer fluid then circulates from the inlet 106a of the bypass line 104 in succession through the first line 112a, the first exchanger 102a, the return line 114, the second exchanger 102b and the second line 112b, to rejoin the bypass line 104 and its outlet 106b through the second valve 116b.

In the mode of operation of FIG. 1, the heat-transfer fluid passes in succession through the two heat exchangers 102a-b for maximum cooling. In this mode, the flow rate and the speed of the heat-transfer fluid are maximized.

In this mode of operation, the distance travelled in the heat exchangers 102a-b is long and the speeds are high, which induces strong pressure drops.

This mode of operation is more particularly used when the temperature of the heat-transfer fluid is above a high threshold.

In the mode of operation of FIG. 2, the first valve 116a is open, the second valve 116b is closed and the third valve 116c is open.

The heat-transfer fluid then circulates from the inlet 106a of the bypass line 104 through the first line 112a and the second line 112b through the first valve 116a, then through each exchanger 102a-b, the return line 114, to rejoin the bypass line 104 and its outlet 106b through the third valve 116c.

In the mode of operation of FIG. 2, the cooling is not maximal and the flow rate of the heat-transfer fluid is divided between the two heat exchangers 102a-b and thus, for each heat exchanger 102a-b, the flow rate and the speed are divided by two.

In this mode of operation, the distance travelled by the heat-transfer fluid in the heat exchangers 102a-b is divided by two by comparison to the preceding mode of operation, and the flow rate is also divided by two by comparison to the preceding mode of operation, which means a pressure drop reduced by a factor lying between four and eight by comparison to the preceding mode of operation.

This mode of operation is more particularly used when the temperature of the heat-transfer fluid is above a low threshold and below the high threshold greater than the low threshold.

This mode of operation is also suitable for ensuring the warming up of the system on start-up, and, in particular, for ensuring the de-icing of the heat exchangers 102a-b.

In the mode of operation of FIG. 3, the first valve 116a is open, the second valve 116b is open and the third valve 116c is closed.

The heat-transfer fluid then circulates from the inlet 106a only in the bypass line 104 to rejoin the outlet 106b through the first valve 116a and the second valve 116b.

In the mode of operation of FIG. 3, the temperature of the heat-transfer fluid is lower than the low threshold and the heat-transfer fluid does not pass through the heat exchangers 102a-b because it does not need to be cooled.

The mode of operation of FIG. 3 corresponds to a bypass mode.

Furthermore, when switching from the mode of operation of FIG. 1 to the mode of operation of FIG. 2, the air which could be located in the system does not have time to settle or form a plug, because the exchangers are always filled up.

The switchover to one or another of the three modes of operation is performed by a control unit such as a controller 120, for example based on the temperature of the heat-transfer fluid measured by a temperature probe linked to the control unit.

From the mode of operation of FIG. 3 which corresponds to the bypass mode, it is then possible to switch to the mode of operation of FIG. 2, and thus, even if hydraulic plugs have appeared in the heat exchangers 102a-b, the distribution of the heat-transfer fluid in the first and second lines 112a-b makes it possible to limit the intensity of the pressure peaks created when the heat-transfer fluid encounters these hydraulic plugs.

After a certain time, it is then possible to switch over to the mode of operation of FIG. 1 if necessary and according to the temperature of the heat-transfer fluid.

The controller 120 is thus configured to, from the mode of operation of FIG. 3, command the valves 116a-c to switch to the mode of operation of FIG. 2, then possibly switch to the mode of operation of FIG. 1.

Thus, from the open position of the first valve 116a, from the open position of the second valve 116b, and from the closed position of the third valve 116c, the controller 120 is configured to command the opening of the third valve 116c and the closing of the second valve 116b.

Then, from the state thus reached, the controller 120 is configured to command the closing of the first valve 116a, the opening of the second valve 116b and the closing of the third valve 116c.

To avoid sudden jerks, the switch from the mode of operation of FIG. 1 to the mode of operation of FIG. 3 is performed also through the mode of operation of FIG. 2.

The various valves 116a-c are, for example, solenoid valves.

To ensure the operation of the exchanger system 100 even in the event of failure, it is preferable to provide for the first valve 116a to be normally open, for the second valve 116b to be normally closed, and for the third valve 116c to be normally open.

While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

Claims

1. An exchanger system containing a heat-transfer fluid and comprising: a first heat exchanger and a second heat exchanger, in which each exchanger comprises a first orifice and a second orifice,a bypass line which extends between an inlet and an outlet,a first line fluidically connected between the bypass line and the first orifice of the first heat exchanger between the inlet and the outlet of the bypass line,a second line fluidically connected between the bypass line and the first orifice of the second heat exchanger between the first line and the outlet of the bypass line,a return line fluidically connected to the two second orifices of the first and second heat exchangers and to the bypass line between the second line and the outlet of the bypass line,a first valve mounted on the bypass line between the first line and the second line,a second valve mounted on the bypass line between the second line and the return line,a third valve mounted on the return line between the two second orifices and the bypass line, anda controller which commands each valve alternately to open or to close.

2. The exchanger system according to claim 1, wherein, from an open position of the first valve, from an open position of the second valve, and from a closed position of the third valve, the controller is configured to command an opening of the third valve and a closing of the second valve.

3. The exchanger system according to claim 2, wherein, from a state that is thus reached by the opening of the third valve and the closing of the second valve, the controller is configured to command a closing of the first valve, an opening of the second valve and a closing of the third valve.