FR3074889A1 - SYSTEM AND METHOD FOR COOLING A GAS STREAM USING A EVAPORATOR - Google Patents

Abstract

The cooling system of a main gas stream (A), comprises an evaporator (1) which comprises an inlet (11), an outlet (12) and a heat exchanger in which a fluid circulates, and which makes it possible to cool a gas stream (B) flowing through the evaporator between the inlet and the outlet of the evaporator, a mixer (2) comprising a main inlet (21) for operation to be fed with the main gas stream (A), an inlet secondary (22) and an outlet (23) which is connected to the inlet (11) of the evaporator (1), and means for recycling (3) a part of the cooled gas flow (C), which have in order to take a part of the cooled gas stream (C) at the outlet of the evaporator (1) in the form of a recycled gas stream (D) and to redirect this recycled gas stream (D) to the inlet secondary (22) of the mixer. In operation, the mixer (2) is able to mix the main gas stream (A) and the recycled gas stream (D) of lower temperature, so as to obtain at the inlet of the evaporator (1) a secondary gas stream ( B) more homogeneous.

Description

SYSTEM AND METHOD FOR COOLING A GAS FLOW USING AN EVAPORATOR

Technical area

The present invention relates to the cooling of a gas flow, and in particular of humid air, by means of an evaporator. It finds its application in different fields, and for example in a non-exhaustive manner in the field of energy recovery in a gas flow by means of a heat pump comprising an evaporator, or dehumidification of a gas flow in the by means of an evaporator, or the recovery of water in the atmosphere, or the regulation of humidity in a refrigeration device, of the refrigerator, freezer, cold room, etc.

Prior art

To date, it is known to cool a gas flow and in particular air, by circulating it in contact with an evaporator. Usually, an evaporator comprises an exchanger in which a fluid, preferably a refrigerant, circulates, which is vaporized in contact with the gas flow with the exchanger by absorbing the thermal energy of the gas flow.

Generally, this evaporator is an integral part of a refrigeration circuit in which the evaporator is associated with at least one condenser, and in which the fluid circulates in a closed circuit.

These refrigeration circuits are for example used in heat pumps allowing the recovery of the thermal energy of the fluid circulating in the refrigeration circuit or in devices for dehumidifying a gas flow in which all or part of the water is recovered. in the gas flow by condensation on the surface of the evaporator exchanger. These dehumidification devices can in particular be used in refrigeration devices such as refrigerators, cold rooms, etc.

When it is desired to cool a flow of moist air by means of an evaporator, for example a flow of moist air at a temperature above 15 ° C to bring it to a temperature slightly above 0 ° C, it there is a significant risk of frost forming on the surface of the evaporator exchanger, because generally to obtain this result the fluid circulating in the evaporator must be at a temperature below 0 ° C. In the event of frost forming, we are forced to carry out an inverse defrosting cycle, which is costly in time and in energy.

A conventional solution to reduce this icing phenomenon consists in increasing the dimensions of the evaporator exchanger, so as to increase the contact surface of the evaporator exchanger with the gas flow to be cooled, which allows comparable results of increasing the temperature of the fluid in the evaporator exchanger. In this solution, the greater the temperature difference between the gas flow to be cooled and the gas flow obtained after cooling, and the larger the dimensions of the exchanger must be to avoid the phenomenon of icing. This solution quickly finds its limits because the increase in the dimensions of the evaporator exchanger increases the manufacturing cost of the exchanger and can in certain applications cause space problems.

Objectives of the invention

A main objective of the invention is to propose a new solution for cooling a gas flow, and in particular an air flow, by means of an evaporator, which in general makes it possible to improve the operation. of the evaporator without increasing the dimensions of the evaporator exchanger.

More particularly, an objective of the invention is to propose a new solution for cooling a gas flow, and in particular an air flow, by means of an evaporator, which makes it possible to obtain the same lowering of the temperature of the gas flow with a higher temperature of the fluid circulating in the evaporator and without increasing the dimensions of the evaporator exchanger and / or with the same temperature of the fluid circulating in the evaporator and decreasing the dimensions of the exchanger of the evaporator or which makes it possible to obtain a greater reduction in temperature of the gas flow without modifying the temperature of the fluid circulating in the evaporator, nor the dimensions of the exchanger of the evaporator.

More particularly, in the field of dehumidification, a secondary objective of the invention is to propose a new solution for cooling a humid gas flow, and in particular a humid air flow, by means of an evaporator, which makes it possible to obtain a dehumidified gas flow having a lower weight in water, without modifying the dimensions of the evaporator exchanger.

More particularly, a secondary objective of the invention is to propose a new solution for cooling a gas flow, and in particular an air flow, by means of an evaporator, which makes it possible to reduce, and preferably d '' avoid the formation of frost on the evaporator exchanger, and in particular by lowering the temperature of the gas flow to a temperature close to 0 ° C.

Summary of the invention

The subject of the invention is therefore a system for cooling a main gas flow (A) which has the following technical characteristics. The cooling system comprises an evaporator which comprises an inlet, an outlet and an exchanger in which a fluid circulates, and which makes it possible to cool a gas flow (B) circulating through the evaporator between the inlet and the outlet of the evaporator, a mixer comprising a main inlet intended for operation to be supplied with the main gas flow (A), a secondary inlet and an outlet which is connected to the inlet of the evaporator, and means for recycling part of the cooled gas flow (C), which have the function of withdrawing part of the cooled gas flow (C) at the outlet of the evaporator in the form of a recycled gas flow (D) and of redirecting this recycled gas flow (D ) up to the secondary input of the mixer; said mixer makes it possible in operation to mix the main gas flow (A) and the recycled gas flow (D) of lower temperature, so as to obtain a more homogeneous secondary gas flow (B) at the inlet of the evaporator.

In the invention, recycling and mixing with the main gas flow to be cooled part of the cooled air flow leaving the evaporator advantageously makes it possible to improve the operation of the evaporator by reducing the difference of temperature between the temperature of the gas flow (secondary gas flow) at the inlet of the evaporator and the temperature of the cooled gas flow at the outlet of the evaporator, compared to a system without recycling and without mixer.

More particularly, the cooling system of the invention may include the following additional and optional characteristics, taken in isolation, or in combination with each other:

- The mixer has a perforated wall or a grid interposed on the path of the main gas flow (A) and the recycled gas flow (B).

- The mixer comprises a stirring means and more particularly a fan, making it possible to stir and mix the main gas flow (A) and the recycled gas flow (D) and / or comprises a stirring means and more particularly a fan, allowing stirring and mixing the secondary gas stream before it leaves the mixer.

- The cooling system includes means for automatically regulating the flow rate of the main gas flow (A) and / or the flow rate of the recycled gas flow (D).

- The cooling system includes first means for measuring the temperature of the cooled gas flow (C) or the recycled gas flow (D), the automatic regulation means being able to automatically adjust the flow rate of the main gas flow (A) and / or the flow rate of the recycled gas stream (D), as a function of the temperature measured by said first measuring means.

- The cooling system comprises second means for measuring the temperature of the secondary gas flow (B), the automatic regulation means being able to automatically adjust the flow rate of the main gas flow (A) and / or the flow rate of the recycled gas flow (D), as a function at least of the temperature measured by said second measuring means.

- The automatic regulation means are capable of automatically adjusting the flow rate of the main gas flow (A) and / or the flow rate of the recycled gas flow (D), at least as a function of the temperature measured by said first measurement means and the temperature measured by said second measuring means.

- The cooling system includes means for measuring the temperature of the main gas flow (A), the automatic regulation means being able to automatically adjust the flow rate of the main gas flow (A) and / or the flow rate of the recycled gas flow ( D), as a function at least of the temperature of the main gas flow (A) measured by said temperature measuring means.

- The cooling system includes first means of measuring the weight of water in the cooled gas flow © or in the recycled gas flow (D), the automatic regulation means being able to automatically adjust the flow rate of the main gas flow (A) and / or the flow rate of the recycled gas flow (D), as a function at least of the weight of water measured by said first measuring means.

- The cooling system includes second means for measuring the weight of water in the main gas flow (A), the automatic regulation means being able to automatically adjust the flow rate of the main gas flow (A) and / or the flow rate of the flow recycled gas (D), depending at least on the weight of water measured by said second measuring means.

- The mixer is able to produce said secondary flow (B) with a maximum temperature difference in the secondary flow (B) which is less than 5 ° C, and preferably 2 ° C.

- The mixer is capable of producing said secondary flow (B) with a maximum temperature difference in the secondary flow (B) which is less than 10% of the temperature difference between the main gas flow (A) and the recycled gas flow (D).

- The recycling means, the mixer, and if necessary the automatic regulation means, are capable of producing said secondary gas flow (B) and said cooled gas flow (C) with a maximum temperature difference between the secondary gas flow ( B) and the cooled gas flow (C) which is sufficiently weak to avoid the formation of frost on the surface of the evaporator exchanger.

- The recycling means, the mixer, and if necessary the automatic regulation means, are capable of producing said cooled gas flow (C) at a temperature below 5 ° C.

- The recycling means, the mixer, and if necessary the automatic regulation means, are capable of producing the secondary gas flow (B) and the cooled gas flow (C) with a maximum temperature difference between the secondary gas flow ( B) and the cooled gas flow (C) which is less than 5 ° C and preferably less than 2 ° C.

- The recycling means, the mixer, and if necessary the automatic regulation means, are capable of producing the cooled gas flow (C) with a water weight of less than 5 g / kg.

The invention also relates to the use of the above-mentioned cooling system for cooling a gas flow, and in particular an air flow.

The invention also relates to a method for cooling a main gas flow (A) in which the main gas flow (A) is mixed with a recycled gas flow (D) of lower temperature, so as to obtain a flow more homogeneous secondary gas (B), and this secondary gas flow (B) is cooled in contact with the exchanger of an evaporator in which circulates a fluid absorbing the thermal energy of the secondary gas flow (B), so as to obtain at the outlet of the evaporator a cooled gas flow (C), a part of this cooled gas flow (C) being withdrawn to form said recycled gas flow (D).

More particularly, the process of the invention may include the following additional and optional characteristics, taken individually, or in combination with one another:

- The maximum temperature difference in the secondary flow (B) is less than 5 ° C, and preferably 2 ° C.

- The maximum temperature difference in the secondary flow (B) is less than 10% of the temperature difference between the main gas flow (A) and the recycled gas flow (D).

- The maximum temperature difference between the secondary gas flow (B) and the cooled gas flow (C) is small enough to avoid the formation of frost on the surface of the evaporator exchanger.

- The cooled gas stream (C) is at a temperature below 5 ° C, and preferably at 2 ° C.

- The maximum temperature difference between the secondary gas flow (B) and the cooled gas flow (C) is less than 5 ° C and preferably less than 2 ° C.

- The weight of water in the cooled gas stream (C) is less than 5 g / kg.

- The main gas flow (A) at the inlet of the mixer is a main gas flow (A ') which is cooled, before entering the mixer, by means of a part (E) of the gas flow which, at the outlet from the evaporator (1), is cooled and not recycled to the mixer.

The invention also relates to an installation for recovering energy in a gas flow comprising a cooling system mentioned above and means making it possible to recover at least part of the thermal energy in the fluid after passage of this fluid in the evaporator.

The invention also relates to an installation for dehumidifying a gas flow comprising a cooling system mentioned above, and more particularly comprising means for recovering the water of condensation on the surface of the evaporator exchanger.

In a particular variant embodiment, the dehumidification installation of a gas flow further comprises an exchanger, which makes it possible to produce the main gas flow (A) at the inlet of the mixer from a first main gas flow (A ') which is cooled, before entering the mixer, by transferring, upstream of the mixer, part of the thermal energy from the first gas flow (A') to the part (E) of gas flow which, at the outlet of the evaporator is not recycled to the mixer.

Brief description of the figures

The characteristics and advantages of the invention will appear more clearly on reading the detailed description below of several particular variant embodiments of the invention, which particular variant embodiments are described by way of non-limiting and non-exhaustive examples of the invention, and with reference to the accompanying drawings in which:

- Figure 1 shows schematically an alternative embodiment of a cooling system of the invention.

- Figure 2 shows a known structure of an energy recovery installation in a gas flow heat pump type (PAC).

- Figure 3 shows a known structure of a dehumidification installation of a gas flow.

- Figures 4 to 7 respectively represent four embodiments of a mixer of a cooling system of the invention.

- Figure 8 is a diagram of an improved variant of a dehumidification installation of the invention.

detailed description

There is shown in Figure 1 a block diagram of a cooling system of a main gas flow A according to the invention. With reference to this FIG. 1, this cooling system comprises an evaporator 1 which is known per se and which is associated with a mixer 2 and with means 3 for recycling part of the gaseous flow cooled at the outlet of the evaporator 1 , and means T for circulating a gas flow, and in particular an air flow, through the mixer 2 and through the evaporator 1, in the form for example of a fan or compressor.

In the particular example of FIG. 1, these means T for circulating a gas flow are positioned downstream of the evaporator 1 and make it possible to create a gas flow by suction. In another variant, these means 1 ′ for circulating a gas flow can for example be positioned upstream of the mixer 2 and make it possible to create a gas flow by blowing.

The evaporator 1 is a device for cooling a gas flow which is known per se, and which comprises an exchanger in which a fluid circulates, preferably a refrigerant, which is vaporized in contact with the gas flow with the exchanger in absorbing thermal energy from the gas flow. The shape and / or structure of the exchanger of the evaporator 1 are of no importance for the invention.

In the context of the invention, the evaporator 1 can be a direct evaporator, that is to say an evaporator in which the gas flow to be cooled is in direct contact with the exchanger in which the fluid which is vaporized circulates . The evaporator 1 can also be an indirect evaporator, that is to say an evaporator comprising at least two exchangers: an intermediate exchanger in which circulates a cooling fluid, such as for example water, and in contact with which the flow gaseous to be cooled is supplied, said cooling fluid making it possible to take thermal energy from the gas flow to be cooled without being vaporized; an exchanger in which a fluid circulates, preferably a refrigerant, which is vaporized by absorbing part of the thermal energy of the fluid of the intermediate exchanger.

There are shown in Figures 2 and 3 two known examples of installation comprising a circuit implementing a direct evaporator 1 in which the fluid F circulates in a closed circuit.

In FIG. 2, the circuit constitutes a heat pump and comprises, in a manner known per se, an evaporator 1 comprising an exchanger 10 connected to the inlet of the exchanger 50 of a condenser 5 via a compressor

4. The exchanger 50 of the condenser 5 is connected to the exchanger 10 of the evaporator 1 via a pressure reducer 6, so as to form a closed loop in which the fluid F, which is preferably a refrigerant, circulates.

In operation, the gas flow B, for example an air flow, at a given temperature is circulated in contact with the exchanger 10 of the evaporator 1, the fluid F being circulated in a closed loop in the circuit by to the compressor 4. In the exchanger 10 of the evaporator, the fluid F, at a temperature below the temperature of the gas flow B, absorbs part of the thermal energy of the gas flow B, by vaporizing. The gas flow B is thus cooled in contact with the exchanger 10. The fluid F is then condensed in the exchanger 50 of the condenser 5, which makes it possible to recover part of the thermal energy in the fluid by heating the exchanger 50. By circulating a gas flow B 'in contact with the exchanger 50 of the condenser 5, said gas flow B' is heated. In another variant, instead of a gas B ’one could heat a liquid, such as water by circulating it in contact with the exchanger 50 of the condenser 5.

There is shown in Figure 3 the known block diagram of a dehumidifier comprising a circuit in which circulates in closed loop a fluid F, which is preferably a refrigerant. Similar to the circuit of FIG. 2, this circuit comprises an evaporator 1 comprising an exchanger 10 in the form of a coil, a condenser 5 comprising a exchanger 50 in the form of a coil, a compressor 4 and a regulator 6. A fan 7 corresponding by example with the fan 1 ′ of FIG. 1, is used to circulate a hot and humid gas flow B, for example a flow of hot air charged with humidity, first in contact with the exchanger 10 of the evaporator 1 , then in contact with the exchanger 50 of the condenser 5. This hot and humid gas flow B is firstly cooled in the form of a cold and dry gas flow B ', all or part of the water vapor contained in this flow B condensing on the surface of the exchanger 10 of the evaporator 1. The condensed water is recovered by gravity in a receptacle 8 and discharged by means of a water pump or by gravity. Then this cold and dry gas flow B ’is heated in the form of a hot and dry gas flow B ″ by circulating in contact with the exchanger 50 of the condenser 5.

In FIG. 1, for the sake of simplification, only the evaporator 1 has been shown, it being specified that this evaporator 1 can for example form an integral part of a closed circuit of an energy recovery installation (heat pump) of the type of that of FIG. 2 or for example forming an integral part of a closed circuit of a dehumidifier of the type of that of FIG. 3.

The evaporator 1 has an inlet 11 for gas flow, an outlet 12 for gas flow and an exchanger 10 (not shown in FIG. 1) in which the fluid F circulates. This evaporator 1 has the function of cooling a gaseous flow circulating at through the evaporator between inlet 11 and outlet 12 of evaporator 1.

The mixer 2 is positioned upstream of the evaporator 1 and comprises a main gas flow inlet 21, a secondary gas flow inlet 22 and a gas flow outlet 23, which is connected to the inlet 11 of the evaporator 1 .

The recycling means 3 have the function of removing a part of the cooled gas flow C at the outlet 12 of the evaporator 1 in the form of a recycled gas flow D and of redirecting this recycled gas flow D to the secondary inlet 22 of mixer 2.

These recycling means 3 comprise for example a return pipe connecting the outlet 12 of the evaporator 1 to the secondary inlet 22 of the mixer. Part of the cooled gas flow C is directed in this return pipe in the form of said recycled gas flow D.

In an alternative embodiment, the return pipe can be equipped with an additional fan or compressor making it possible, as the case may be, to draw or push into said pipe part of the cooled gas flow C at the outlet 12 of the evaporator 1, under the form of said recycled gas stream D, up to the secondary inlet 22 of the mixer 2.

In operation, the main gas flow A to be cooled, and for example an air flow which may be humid, is mixed in the mixer 2, upstream of the evaporator 1, with the recycled gas flow D of lower temperature, of so as to obtain a more homogeneous secondary gas flow B at the inlet of the evaporator 1. Then this secondary gas flow B is cooled in contact with the exchanger of the evaporator 1 in which the fluid F absorbing thermal energy circulates of the secondary gas flow B. A cooled gas flow C is obtained at the outlet of the evaporator 1, part of this cooled gas flow C being taken off by the recycling means 3.

In practice, the "more homogeneous" character of the secondary gas flow B results in a more homogeneous temperature in the secondary gas flow B compared to the temperature difference between the main gas flow A and the recycled gas flow D at the inlet from mixer 2.

In other words, the maximum temperature difference in the secondary gas flow B (temperature difference between the hottest point and the coldest point in the secondary gas flow) is less, and preferably much less, than the maximum temperature difference between the main gas flow A and the recycled gas flow D.

There are shown in Figures 4 to 7, different embodiments of a mixer 2, it being specified that these examples are not limiting of the invention and that other mixer structures fulfilling the same function can be envisaged.

In FIG. 4, the mixer 2 comprises a mixing enclosure 23, in which is mounted at least one grid 24 or a perforated plate which separates the enclosure 23 into two upstream 25 and downstream 26 chambers, the two gas flow inlets 21 and 22 being provided in the upstream chamber 25, and the evaporator 1 being mounted in the downstream chamber 26.

In operation, the main gas flow A and the recycled gas flow D are introduced into the upstream chamber 25. The grid or the perforated plate 24 has the function of creating in the upstream chamber 25, on the path of the gas flows A and D, a pressure drop which makes it possible to mix the two gas flows A and B in a turbulent manner and to obtain a more homogeneous secondary gas flow B which passes through the grid or the perforated plate 24. This more homogeneous secondary gas flow B leaves the downstream chamber 26 passing in contact with the evaporator 1.

The opening rate of the grid or the perforated plate 24 (ratio between the sum of the sections of the openings of the grid or the perforated plate 24 crossed by the gas flow and the total surface of the grid or the perforated plate 24 ) and the section of the openings of the grid or of the perforated plate 24 will be chosen depending in particular on the degree of homogeneity desired for the secondary air flow B and the flow rates of the flows A, D and B.

The mixer 2 of FIG. 5 has been improved with respect to the mixer of FIG. 4 by adding a stirring means 27, and in particular a fan in the upstream chamber 25, upstream of the grid or the perforated plate 24. This means stirring 27 improves the homogeneity of the secondary gas flow B, by mechanically stirring and mixing the main gas flow and the recycled gas flow D in the upstream chamber 25.

The mixer 2 of FIG. 6 has been improved with respect to the mixer of FIG. 4 by adding a stirring means 27, and in particular a fan in the downstream chamber 26, downstream of the grid or the perforated plate 24. This means stirring 27 improves the homogeneity of the secondary gas flow B, by mechanically stirring and mixing the secondary gas flow B in the downstream chamber 26 before it leaves the mixer 2.

FIG. 7 represents another example of mixer 2 which differs from that of FIG. 4 by the shape of the downstream chamber 25 which forms a Y connector

The recycling of the air flow D upstream of the evaporator advantageously makes it possible to lower the temperature difference between the inlet and the outlet of the evaporator. Compared to a conventional solution without recycling and without mixer, it is thus possible for example to obtain at the outlet of the evaporator 1 the same lowering of the temperature of the gas flow (temperature difference between the main gas flow A and the gas flow cooled C) with a higher temperature of the fluid F circulating in the evaporator 1 and without increasing the dimensions of the exchanger of the evaporator 1 and / or with the same temperature of the fluid F circulating in the evaporator 1 and by reducing the dimensions of the evaporator exchanger 1. Compared to a conventional solution without recycling and without a mixer, it is also possible for example to obtain a greater reduction in temperature of the gas flow (temperature difference between the main gas flow A and the cooled gas flow C) without modifying the temperature of the fluid F circulating in the evaporator or the dimensions of the exchanger of the evaporator.

The mixing of the main gas flow A and the recycled gas flow D by the mixer 1 is important in order to avoid the presence in the secondary gas flow of cold spots in particular at the temperature of the recycled gas flow D and of hot spots in particular at the temperature of the main gas flow A which could locally cause frost to form on the evaporator exchanger 1.

For the implementation of the invention, it is preferable that the secondary flow B at the outlet of the mixer 2 is as homogeneous as possible.

More particularly, the mixer 1 is designed so as to obtain a maximum temperature difference in the secondary flow B (temperature difference between the hottest point and the coldest point in the secondary gas flow) which is less than 5 ° C. , and preferably below 2 ° C

More particularly, the mixer 1 is designed so as to obtain a maximum temperature difference in the secondary flow B (temperature difference between the hottest point and the coldest point in the secondary gas flow) which is less than 10% of the temperature difference between the main gas flow A and the recycled gas flow D at the inlet of the mixer 2

The combination of recycling part of the cooled gas flow C and of the mixture with the main gas flow A allows more particularly in certain applications, such as for example energy recovery or dehumidification to lower the temperature of the cooled gas flow C at values close to 0 ° C, and in particular below 5 ° C, and preferably at 2 ° C, avoiding the formation of frost on the surface of the exchanger of the evaporator 1 and without using any large area exchangers.

More particularly in many applications, the recycling means 3 and the mixer 2 are designed so as to obtain a maximum temperature difference between the secondary air flow B and the cooled air flow C which is sufficiently low to avoid the formation of frost on the surface of the evaporator exchanger 1 and / or so as to obtain a maximum temperature difference between the secondary air flow B and the cooled air flow C which is less than 5 ° C and preferably less than 2 ° C.

Also the combination of recycling part of the cooled gas flow C and of the mixture with the main gas flow A allows more particularly in certain applications, such as for example dehumidification, to reduce the weight of water in the cooled gas flow C at very low values, without using large surface exchangers.

More particularly, the recycling means 3 and the mixer 2 are designed so as to obtain a flow of cooled air C having a weight of water less than 5 g / kg of dry air.

In a particular implementation of the cooling system of the invention, it is up to the person skilled in the art, depending on the application, for example to regulate on a case-by-case basis the flow rate of the recycled gas stream D relative in particular to the flow rate of the main gas flow A and the characteristics of the main gas flow A (in particular temperature, weight in water) at the inlet of the mixer as a function in particular of the desired temperature difference in steady state between the temperature of the secondary flow at inlet of evaporator 1 and the temperature of the cooled gas flow C at the outlet of evaporator 1 or as a function of the target temperature, in steady state, for the cooled gas stream C at the outlet of evaporator 1, or as a function the target weight of water, in steady state, in the cooled gas flow C at the outlet of the evaporator 1.

In another particular variant embodiment, the cooling system may include automatic regulation means RA for the flow rate of the main gas flow A and / or the flow rate for the recycled gas flow D, these automatic regulation means RA being able in particular to control the means 1 'for circulating the gas flow. These automatic regulation means are implemented in the form, for example, of a programmable controller or any other equivalent electronic control circuit.

More particularly, the cooling system may include first means T1 for measuring the temperature of the cooled gas flow C or of the recycled gas flow D (for example temperature probe or equivalent placed in the cooled gas flow C or in the recycled gas flow D), the automatic regulation means RA being able to automatically adjust the flow rate of the main gas flow A and / or the flow rate of the recycled gas flow D, as a function of the temperature measured by said first measurement means.

More particularly, the cooling system may include second means T2 for measuring the temperature of the secondary gas flow B at the inlet (for example temperature probe or equivalent placed in the gas flow B), the automatic regulation means RA being able to automatically adjust the flow rate of the main gas flow A and / or the flow rate of the recycled gas flow D, as a function of the temperature measured by said first measuring means and the temperature measured by said first measuring means.

More particularly, the cooling system may include means T3 for measuring the temperature of the main gas flow A at the inlet of the mixer 2, the automatic regulation means RA being able to automatically adjust the flow rate of the main gas flow A and / or the flow rate of the recycled gas flow D, at least as a function of the temperature of the main gas flow A measured by said temperature measuring means, and if necessary as a function of the temperature of the cooled gas flow measured by said first means of measuring and optionally, if necessary, the temperature in the secondary gas flow B measured by said second measuring means.

More particularly, the cooling system may include first means H1 for measuring the weight of water in the cooled gas flow C or in the recycled gas flow D (for example hygrometric probe or equivalent placed in the gas flow C or in the gas flow recycled D), the automatic regulation means RA being able to automatically adjust the flow rate of the main gas flow A and / or the flow rate of the recycled gas flow D, as a function of the weight of water measured by said first measurement means.

More particularly, the cooling system may include second means H2 for measuring the weight of water in the main gas flow A, for example hygrometric probe or equivalent placed in the main gas flow A, the automatic regulation means RA being able to adjust automatically the flow rate of the main gas flow A and / or the flow rate of the recycled gas flow D, at least as a function of the weight of water measured by said second measuring means.

FIG. 8 shows an alternative embodiment of a dehumidification installation which makes it possible to produce at the outlet a dehumidified gas flow F, and in particular a dehumidified air flow F at a temperature Tf + ΔΤ, from a humid gas flow A ′, and in particular a flow of humid air, at a temperature Te.

This dehumidification installation comprising a cooling system with mixer 2 and evaporator 1 as previously described, and an exchanger G, for example enthalpy exchanger of the double flow type or of the heat pipe type, which makes it possible to transfer, upstream of the mixer 2, a part of the thermal energy from the humid gas flow A ′ to the gas flow E which is not recycled at the outlet of the evaporator 1, so as to produce said dehumidified air flow F at a temperature Tf + ΔΤ. The main gas flow A at the inlet of the mixer 2 of the cooling system corresponds to the wet gas flow A ’cooled to a temperature Te- ΔΤ after passing through the exchanger G.

By way of example only, the temperature Te can be 30 ° C; the temperature Tf can be 4 ° C; The temperature difference ΔΤ can be 12 ° C. The dehumidified gas stream F is at a temperature of 16 ° C (Tf + ΔΤ). In this case, the cooling device of the invention needs to cool the main gas flow A only from 18 ° C (Te- ΔΤ) to 4 ° c (Tf), which represents a significant energy saving .

The implementation of this exchanger G therefore advantageously makes it possible to reduce the energy expenditure to obtain dehumidification.

Claims (28)

1. Cooling system for a main gas flow (A), comprising an evaporator (1) which comprises an inlet (11), an outlet (12) and an exchanger (10) in which a fluid (F) circulates, and which makes it possible to cool a gas flow (B) circulating through the evaporator between the inlet and the outlet of the evaporator, a mixer (2) comprising a main inlet (21) intended in operation to be supplied with the gas stream main (A), a secondary inlet (22) and an outlet (23) which is connected to the inlet (11) of the evaporator (1), and means for recycling (3) part of the gas flow cooled (C), which have the function of taking part of the cooled gas flow (C) at the outlet of the evaporator (1) in the form of a recycled gas flow (D) and of redirecting this recycled gas flow (D ) up to the secondary inlet (22) of the mixer, said mixer (2) making it possible in operation to mix the main gas flow l (A) and the recycled gas flow (D) of lower temperature, so as to obtain a more homogeneous secondary gas flow (B) at the inlet of the evaporator (1). 2. Cooling system according to claim 1, in which the mixer (2) comprises a perforated wall (24) or a grid (24) interposed on the path of the main gas flow (A) and the recycled gas flow (B). 3. Cooling system according to any one of the preceding claims, in which the mixer (2) comprises a stirring means (27) and more particularly a fan, making it possible to stir and mix the main gas flow (A) and the recycled gas stream (D) and / or comprises a stirring means (27) and more particularly a fan, making it possible to stir and mix the secondary gas stream (B) before it leaves the mixer (2). 4. Cooling system according to any one of the preceding claims, comprising means for automatic regulation (RA) of the flow rate of the main gas flow (A) and / or of the flow rate of the recycled gas flow (D). 5. Cooling system according to claim 4, comprising first means for measuring (T1) the temperature of the cooled gas flow (C) or of the recycled gas flow (D), the automatic regulation means being capable of automatically adjusting the flow rate. the main gas flow (A) and / or the flow rate of the recycled gas flow (D), as a function of the temperature measured by said first measuring means. 6. Cooling system according to claim 4 or 5, comprising second means (T2) for measuring the temperature of the secondary gas flow (B), the automatic regulation means being able to automatically adjust the flow rate of the main gas flow (A ) and / or the flow rate of the recycled gas stream (D), depending at least on the temperature measured by said second measurement means (T2). 7. Cooling system according to claims 5 and 6, in which the automatic regulation means are capable of automatically adjusting the flow rate of the main gas flow (A) and / or the flow rate of the recycled gas flow (D), at least as a function the temperature measured by said first measuring means (T1) and the temperature measured by said second measuring means (T2). 8. Cooling system according to any one of claims 4 to 7, comprising means for measuring (T3) the temperature of the main gas flow (A), the automatic regulation means being able to automatically adjust the flow rate of the gas flow main (A) and / or the flow rate of the recycled gas flow (D), depending at least on the temperature of the main gas flow (A) measured by said temperature measuring means (T3). 9. Cooling system according to any one of claims 4 to 8, comprising first means for measuring (H1) the weight of water in the cooled gas flow (C) or in the recycled gas flow (D), the means for automatic regulation being able to automatically adjust the flow rate of the main gas flow (A) and / or the flow rate of the recycled gas flow (D), at least as a function of the weight of water measured by said first measuring means (H1). 10. Cooling system according to any one of claims 4 to 9, comprising second means of measurement (H2) of the weight of water in the main gas flow (A), the automatic regulation means being able to automatically adjust the flow rate. of the main gas flow (A) and / or the flow rate of the recycled gas flow (D), depending at least on the weight of water measured by said second measuring means (H2). 11. Cooling system according to any one of the preceding claims, in which the mixer (2) is capable of producing said secondary flow (B) with a maximum temperature difference in the secondary flow (B) which is less than 5 ° C, and preferably at 2 ° C. 12. Cooling system according to any one of the preceding claims, in which the mixer (2) is capable of producing said secondary flow (B) with a maximum temperature difference in the secondary flow (B) which is less than 10% of the temperature difference between the main gas flow (A) and the recycled gas flow (D). 13. Cooling system according to any one of the preceding claims, in which the recycling means (3), the mixer (2), and if necessary the automatic regulation means, are capable of producing said secondary gas flow (B ) and said cooled gas flow (C) with a maximum temperature difference between the secondary gas flow (B) and the cooled gas flow (C) which is sufficiently low to avoid the formation of frost on the surface of the heat exchanger 'evaporator (1). 14. Cooling system according to any one of the preceding claims, in which the recycling means (3), the mixer (2), and where appropriate the automatic regulation means, are capable of producing said cooled gas flow (C ) at a temperature below 5 ° C. 15. Cooling system according to any one of the preceding claims, in which the recycling means (3), the mixer (2), and where appropriate the automatic regulation means, are capable of producing the secondary gas flow (B ) and the cooled gas flow (C) with a maximum temperature difference between the secondary gas flow (B) and the cooled gas flow (C) which is less than 5 ° C and preferably less than 2 ° C. 16. Cooling system according to any one of the preceding claims, in which the recycling means (3), the mixer (2), and where appropriate the automatic regulation means, are capable of producing the cooled gas flow (C ) with a water weight of less than 5 g / kg. 17. Use of the cooling system of any one of the preceding claims for cooling a gas flow (A), and in particular an air flow. 18. Method for cooling a main gas flow (A), in which the main gas flow (A) is mixed in a mixer (2) with a recycled gas flow (D) of lower temperature, so as to obtain a more homogeneous secondary gas flow (B), and this secondary gas flow (B) is cooled in contact with the exchanger of an evaporator (1) in which circulates a fluid (F) absorbing the thermal energy of the secondary gas flow ( B), so as to obtain at the outlet of the evaporator (1) a cooled gas flow (C), part of this cooled gas flow (C) being withdrawn to form said recycled gas flow (D). 19. The cooling method according to claim 18, wherein the maximum temperature difference in the secondary flow (B) is less than 5 ° C, and preferably 2 ° C. 20. A cooling method according to any one of claims 18 or 19, in which the maximum temperature difference in the secondary flow (B) is less than 10% of the temperature difference between the main gas flow (A) and the recycled gas stream (D). 21. A cooling method according to any one of claims 18 to 20, in which the maximum temperature difference between the secondary gas flow (B) and the cooled gas flow (C) is sufficiently small to avoid the formation of frost at the surface of the evaporator exchanger (1). 22. A cooling method according to any one of claims 18 to 21, wherein the cooled gas flow (C) is at a temperature below 5 ° C, and preferably at 2 ° C. 23. A cooling method according to any one of claims 18 to 22, in which the maximum temperature difference between the secondary gas flow (B) and the cooled gas flow (C) is less than 5 ° C and preferably less at 2 ° C. 24. A cooling method according to any one of claims 18 to 23, wherein the weight of water of the cooled gas stream (G) is less than 5 g / kg. 25. A cooling method according to any one of claims 18 to 24, wherein the main gas flow (A) at the inlet of the mixer (2) is a main gas flow (A ') which is cooled, before its entry in the mixer (2), by means of a part (E) of the gas flow which, at the outlet of the evaporator (1), is cooled and not recycled to the mixer (2). 26. Installation for recovering energy in a gas flow comprising a cooling system of any one of claims 1 to 16 and means (4, 5) making it possible to recover at least part of the thermal energy in the fluid ( F) after passage of this fluid through the evaporator (1). 27. installation for dehumidifying a gas flow comprising a cooling system of any one of claims 1 to 16, and more particularly comprising means (4, 5, 8, 9) for recovering the condensation water at the surface of the evaporator exchanger (1). 28. Installation for dehumidifying a gas stream according to claim 27, further comprising an exchanger (G), which makes it possible to produce the main gas stream (A) at the inlet of the mixer (2) from a first main gas flow (A ') which is cooled, before entering the mixer (2), by transferring, upstream of the mixer (2), part of the thermal energy from the first gas flow (A') to the part (E) of gas flow which, at the outlet of the evaporator (1) is not recycled to the mixer (2).