WO2020115449A2

WO2020115449A2 - Refrigeration installation

Info

Publication number: WO2020115449A2
Application number: PCT/FR2019/052958
Authority: WO
Inventors: Hugues GOLZIO; Jean-Eric CARTRY; Philippe CERTIAT
Original assignee: Beg Ingenierie
Priority date: 2018-12-06
Filing date: 2019-12-06
Publication date: 2020-06-11
Also published as: EP3891447A2; ES2887318T1; FR3089603A1; WO2020115449A3; FR3089603B1

Abstract

The invention relates to a refrigeration installation comprising a very low-temperature module (TB) having a first circuit carrying a first refrigerant, comprising a first compressor (3, 71), a first heat exchanger (5), a first expansion valve (7, 52), a first pump (11, 51) and a first evaporator (13, 54). The invention is characterized in that the first refrigerant is a fluid with a liquid/vapor phase change, and in that this installation comprises a reservoir (9, 70), the lower part of which communicates with said first expansion valve (52) and with said first pump (11, 51), and the upper part of which communicates with said first evaporator (13, 54) and said first compressor (3, 71).

Description

DESCRIPTION

TITLE: REFRIGERATION SYSTEM

The present invention relates to a refrigeration installation, in particular for foodstuffs.

Are known from the prior art autonomous refrigeration installations, that is to say not connected to the electrical current of the sector.

Such installations, connected for example to photovoltaic panels, use the electric current produced by these panels to operate a conventional refrigeration circuit, comprising a condenser disposed outside the enclosure to be cooled, and an evaporator disposed at the inside this enclosure.

In night operation, that is to say when the photovoltaic panels no longer produce electricity, different solutions exist to continue to produce cold.

A first solution consists in recharging electric accumulators during the day by means of the current produced by the photovoltaic panels, these accumulators restoring during the night the electric current necessary for the operation of the refrigeration installation. This first solution requires the use of high capacity accumulators whose lifetime is limited, which induces high costs.

A second solution consists in using ice, manufactured by the refrigeration installation during the day, and the melting of which during the night provides the frigories necessary to maintain the low temperatures in the refrigerated enclosure. This second solution has the drawback of not making it possible to reach very low temperatures, and of not making it possible to control or regulate the amount of thermal reserve available.

Thus, the present invention aims to provide a refrigeration installation making it possible to reach very low temperatures, and the available thermal reserve of which can be perfectly known and regulated.

This object of the invention is achieved with a refrigeration installation comprising a very low temperature module comprising a first circuit conveying a first refrigerant, comprising a first compressor, a first heat exchanger, a first expansion valve, a first pump and a first evaporator , remarkable in that the first refrigerant is a liquid / vapor phase change fluid, and in that this installation comprises a reservoir, the lower part of which communicates with said first pressure reducer and with said first pump, and the upper part of which communicates with said first evaporator and said first compressor.

The use of a tank containing a coolant with change of liquid / vapor phase makes it possible, in an extremely simple and perfectly controllable manner, to enrich the liquid phase of this tank in daytime operation when the compressor is running, then, by simple pumping and evaporation of the liquid phase towards the gaseous phase of the cooling fluid located in the tank, to cool with a very low energy consumption the products located in the refrigerated enclosure, in night mode.

This low energy can be supplied by low capacity accumulators.

According to other optional features of the first embodiment of the present invention:

- It further comprises a low temperature module connected in cascade to said first heat exchanger;

- Said low temperature module comprises a second cooling circuit comprising a cold source formed by a solid / liquid phase change material, and a third cooling circuit comprising means for cooling this material;

the second cooling circuit comprises a unit for storing said material with a solid / liquid phase change, and it carries a second cooling fluid circulating in a second pump, in a second heat exchanger, in a third heat exchanger, and in said first heat exchanger, then returning to said storage unit;

- Said third cooling circuit conveys a third cooling fluid circulating in a second compressor disposed downstream of the second heat exchanger, in a condenser, in a second regulator, then returning to said second heat exchanger; - Said third cooling fluid can be a synthetic cooling fluid of the hydro-fluoro-carbon olefin type; of the hydro-fluoro-olefins type, of the hydro-fluoro-carbides type or of carbon dioxide of the R744 type;

- Said first cooling fluid can be carbon dioxide of the R744 type, of synthesis of the hydro-fluoro-carbide type or of the hydro-fluoro-olefin type.

The use of carbon dioxide type R744 is particularly suitable as a coolant with liquid / vapor phase change, since it is both very easily pumpable and not very dangerous for the environment.

According to other optional features of the second embodiment of the present invention:

- the very low temperature module comprises a condenser, the first heat exchanger and the condenser being arranged in the same storage unit;

- the very low temperature module includes a tank configured to act as a liquid / vapor separator connected on the one hand to the tank and on the other hand to the storage unit and a low pressure vapor / liquid bottle, the tank being configured to conveying said fluid from a pump configured to circulate the fluid from the low pressure vapor / liquid bottle to said storage unit, passing through the evaporator, to the vapor / liquid separator, said reservoir (70) being configured to have the function of an expansion tank in night mode;

- It further comprises a low temperature module connected in cascade or direct delivery, on the one hand to said first compressor by a first connection and on the other hand to said low pressure vapor / liquid bottle by a second connection;

- A second compressor is included and connected by pipes, on the one hand to the separator and on the other hand to the first connection;

- Said first cooling fluid can be carbon dioxide of the R744 type, a synthetic cooling fluid of the hydro-fluoro-carbon type or of the hydro-fluoro-olefin type.

Other characteristics and advantages of the present invention will become apparent in the light of the description which follows, and on examining the appended figure, representing an installation according to the present invention, in the particular case where it comprises on the one hand a very low temperature cooling circuit, and on the other share a low temperature cooling circuit connected in cascade with the previous one.

It should however be understood that the invention is not limited to this complex installation, and that it relates more particularly to the very low temperature cooling circuit, which could be used independently of the low temperature cooling circuit.

In the description below, the reservoir configured to act as a liquid / vapor separator is called a "separator".

[Fig. 1] shows a diagram of a refrigeration installation according to a first embodiment of the invention.

[Fig. 2] shows a diagram of a refrigeration installation according to a second embodiment of the invention.

Referring to the appended FIG. 1, it can be seen that the very low temperature circuit, designated by the general reference TB, comprises pipes 1 carrying a first cooling fluid, these pipes connecting together a first compressor 3 supplied by a source of electrical energy, a first heat exchanger 5, a first regulator 7, a tank 9, a first pump 11 and an evaporator 13 located in an enclosure where it is desired to maintain products, such as foodstuffs, at a temperature with a very low core, typically located in a range from -20 ° C to -40 ° C.

More specifically, the reservoir 9 is connected in its lower part on the one hand to the first regulator 7, and on the other hand to the first pump 11, and in its upper part on the one hand to the evaporator 13 and to the first compressor 3.

The pipes 1 and the tank 9 contain a pumpable coolant with change of liquid / vapor phase, such as carbon dioxide R744.

Thus, in the lower part of the reservoir 9 is the liquid phase of this fluid, and in the upper part of this reservoir is the vapor phase of this liquid.

The low temperature cooling circuit, designated by the general reference B in the appended figure, firstly comprises a unit 15 for storing a cooling material with solid / liquid phase change. Such a material, known per se, may be a water-insoluble organic phase change material, derived from plant-based raw materials and in the form of a crystalline wax or an oily, non-corrosive liquid and nontoxic.

Typically, this phase change material liquefies at about -21 ° C, and crystallizes at -27 ° C.

The storage unit 15 is connected by pipes 17 to a second pump 19, to a second heat exchanger 21, to a third heat exchanger 23 located in an enclosure, distinct from the previous one, in which there are products that the it is desired to maintain a core temperature typically located in a range from -5 ° C to +10 ° C.

The third heat exchanger 23 is itself connected to the first heat exchanger 5, which in turn is connected to the storage unit 15.

In the pipes 17 a second cooling fluid circulates.

The second heat exchanger 21 is connected by pipes 25 successively to a second compressor 27, to a condenser 28, to a fluid storage tank 29, and to a second pressure reducer 31 itself connected to this second heat exchanger 21.

A third cooling fluid, such as a synthesis fluid of the hydro-fluoro-carbon olefin type, of the hydro-fluoro-carbon type or of carbon dioxide R744, circulates in the pipes 25.

The operating mode of the above-mentioned refrigeration installation is as follows.

During the day, electric current which can come from photovoltaic panels, or from any other current generator not connected to the sector (for example electric energy from wind) supply the compressors 3 and 27, as well as the pumps 11 and 19.

The first compressor 3 makes it possible to compress the vapor phase of the first cooling fluid located in the upper part of the tank 9.

The heat released by this compression is removed via the first heat exchanger 5 in the second cooling fluid circulating in the pipes 17 of the low temperature module. During its expansion through the pressure reducer 7, the first cooling fluid sees its temperature drop considerably, and its pumping by the pump 11 towards the evaporator 13 makes it possible to cool the products located in the enclosure to very low temperature.

In doing so, this evaporation also has the effect of enriching the vapor phase located inside the tank 9.

Cascade cooling of the first cooling fluid flowing in the pipes 1 by the second cooling fluid flowing in the pipes 17 is effected by means of the first heat exchanger 5.

In daytime operation, the second cooling fluid, the circulation of which is ensured by the second pump 19, is cooled by the third cooling fluid circulating in the pipes 25, itself undergoing a compression / expansion cycle thanks to the second compressor 27 and to the second regulator 31.

More precisely, this third cooling fluid makes it possible, via the second heat exchanger 21, to lower the temperature of the second cooling fluid flowing in the pipes 17 sufficiently, to ensure, during the day, the crystallization of the material to be changed. solid / liquid phase located in the storage unit 15, and whose crystallization temperature can typically be of the order of -27 ° C.

The second coolant circulating in the pipes 17 makes it possible, thanks to a third heat exchanger 23, to ensure a low temperature in an enclosure where there are products of which it is desired to keep the core temperature within a range which can typically range from - 5 ° C to +10 ° C.

During the night, the external source of electricity supply (for example photovoltaic panels) no longer produces electricity, and the compressors 3 and 27 stop working. Only the pumps 11 and 19 operate on accumulators of relatively low capacity.

The operation of the pump 11, making it possible to circulate the first cooling fluid through the evaporator 13, gradually converts the liquid phase of this fluid located in the reservoir 9 into the gas phase located in the upper part of this tank, supplying in the frigories necessary to maintain at very low temperature the products located in the enclosure concerned.

Regarding the low temperature enclosure, the desired low temperature is maintained by the circulation of the second cooling fluid in the pipes 17 by means of the second pump 19, this second fluid being cooled by the melting of the change material inside the unit 15.

FIG. 2 shows a refrigeration installation according to a second embodiment of the invention.

It can be seen that the very low temperature circuit TB includes elements connected to each other by pipes 1. The pipes 1 are configured to convey a first coolant for a low vapor / liquid pressure bottle 50 by pumping double pumps 51 refrigerant.

The low pressure bottle 50 includes a pressure reducer, here a valve 52, which can be electronic as well as a sensor 53 for the level of the liquid contained in the bottle 50. The pumped fluid is then directed to evaporators 54 mounted in parallel making it possible to cool the air in the cold rooms of each evaporator 54 at a given temperature T, the air being blown by fans 55.

Each evaporator outlet extends into a single pipe 1 at a junction point 56 in order to connect to a storage unit 57 having several functions such as that of an evaporator, a condenser or a tank latent heat.

In parallel, a pipe 1 directly connects the double pumps 51 to the storage unit 57.

At least one electromagnetic valve 52 is integrated between each element of the installation connected by the pipes 1, the opening and / or closing of each valve 52 being controllable, for example on order or by temperature probe.

A vapor / liquid separator 60 is connected by a pipe 1 to the storage unit 57. In parallel, another pipe 1 directly connects the pipe 1 joining each evaporator outlet 54 to the separator 60.

The separator 60 is also connected directly to the low pressure vapor / liquid bottle 50 by a pipe 1. The separator 60 further comprises a liquid level sensor making it possible to control the corresponding valve 52, here referenced 52a.

The separator 60 is itself connected to a tank 70. This tank 70 is a vapor bottle known as an expansion tank. Indeed, the tank 70 has the function of an expansion tank in night mode and in particular by preventing a rise. under pressure in the evaporator 54, the separator 60 and the low pressure bottle 50 when the fluid has cooled. The reservoir 70 is connected to a first compressor 71.

A low temperature module B is connected in cascade or in direct delivery, on the one hand to the first compressor 71 by a first connection 72 and on the other hand to said low vapor / liquid pressure bottle 50 by a second connection 73.

In addition, a second compressor 74 is included and connected by pipes 1, on the one hand to the separator 60 and on the other hand to the first connection 72. The low temperature module B comprises an air condenser 80 connected to a vertical tank 81 In the following paragraphs, the operation of the invention according to the second embodiment is explained.

In daytime mode, electric current which can come for example from photovoltaic panels, or from any other current generator not connected to a sector, for example electric energy of wind origin, feed the compressors 71, 74 and the condenser to air 80 as well as the double pumps 51 and the fans 55 of the evaporators 54.

During its expansion through the pressure reducer, here a valve 52 arranged at the level of the low vapor / liquid pressure bottle 50, the refrigerant sees its temperature T drop considerably, and its pumping by the double pumps 51 towards the 'evaporator 54 makes it possible to cool the products located in the enclosure at very low temperature TB.

The operation of the double pumps 51, making it possible to circulate the refrigerant through the evaporator 54, gradually converts the liquid phase of this fluid located in the low pressure vapor / liquid bottle 50 into the gaseous phase, supplying the frigories in passing. necessary for keeping products located in the enclosure at very low temperatures.

In so doing, this evaporation also has the effect of enriching the vapor phase at the junction point 56 of the outlet of each evaporator 54. In night mode, the valve 52 arranged between the junction point 56 of the outlet of each evaporator 54 is open, the valve 52 disposed at the level of the pipe 1 directly connecting the junction point 56 of the outlet of each evaporator 54 to the separator 60 is closed and this enriched vapor phase passes through the storage unit 57 and partially condenses by melting the MCP (Phase Change Material) which gives up its latent heat to the condensing vapor.

In night mode, the vapor and liquid phases coming from the evaporators 54 and from the storage unit 57 by the aforementioned pipe paths 1, are separated by the separator 60 and the excess pressure is absorbed by the tank 70 having been brought back at a pressure PI lower than a pressure P2 of saturation equivalent to temperature T in daytime mode.

In daytime mode, the valves 52 respectively disposed at the level of the pipe 1 directly connecting the junction point 56 of the outlet of each evaporator 54 to the separator 60 and at the level of the pipe 1 directly connecting the double pumps 51 to the storage unit 57 are open, the valve 52 connecting the junction point 56 of the outlet of each evaporator 54 to the storage unit 57 is closed. The double pumps 51 always pass the liquid through the evaporators 54 and via the valve 52, directly connecting the double pumps 51 to the storage unit 57, open through the storage unit 57. The evaporation of the refrigerant through the storage unit 57 solidifies the MCP.

In daytime mode, at line 1 connecting the separator 60 to the storage unit 57 and the separator 60 to the junction point 56 of the outlet of each evaporator 54, the vapor and liquid phases coming from the evaporators 54 and the storage unit 57 are separated in by the separator 60 and the excess steam is sucked in by the second compressor 74 while the excess liquid is evacuated via the valve 52 disposed at the level of the pipe 1 directly connecting the low pressure bottle vapor / liquid 50 to the separator 60, towards the low pressure vapor / liquid bottle 50, the valve 52 being controlled by the liquid level sensor.

During the night, the external source of electric supply, for example the photovoltaic panels, no longer produces electricity, and the first and second compressors 71 and 74 stop working. Only the double pumps 51 and the fans 55 of evaporators 54 operate on accumulators of relatively low capacity.

In daytime mode, at full electric charge by the photovoltaic panels for example, or other intermittent sources, the second compressor 74 makes it possible to solidify the MCP melted in phase and the first compressor 71 makes it possible to lower the pressure of the tank 70 to the value equivalent of saturation pressure PI at temperature T-30 ° C. In all cases, the pressure PI will be greater than 1 bar and at the triple point of the fluid used.

Depending on the system on which this intermittent stage is grafted, an additional low temperature circuit B of refrigeration production may be necessary, the operation of which will be controlled by the first and second compressors 71 and 74, therefore in daytime mode only.

As can be understood in the light of the preceding description, the refrigeration installation according to the invention, which can be used either only with the very low temperature module, or with a combination of this module with the low temperature module, allows the desired low temperatures to be maintained when the installation is no longer supplied with electric current.

This invention is therefore particularly suitable for refrigeration installations supplied by autonomous and intermittent electrical sources, such as photovoltaic panels, or else wind turbines.

An installation according to the invention can thus be installed in very remote areas, not connected to the electrical current of the sector.

Electronic regulation can advantageously be envisaged, in order to control the charges and discharges of stored frigories in connection with the available charge of electric accumulators in night mode and the peak current available in day mode.

In a particularly advantageous manner, the refrigeration installation according to the embodiments of the invention can be mobile, and include 2 enclosures, one very low temperature with the objective of obtaining a core temperature of the refrigerated products located between - 20 ° C and -40 ° C, and the other low temperature with the aim of obtaining a core temperature of the refrigerated products between -5 ° C and +10 ° C. Of course, the present invention is in no way limited to the embodiment described is shown.

Other fluids and phase change materials than those which have been mentioned may be used. For example, the refrigerant R404A (zeotropic mixture of fluorethanes) can be an alternative to carbon dioxide R744.

Claims

1. Refrigeration installation comprising a very low temperature module (TB) comprising a first circuit conveying a first refrigerant, comprising a first compressor (3, 71), a first heat exchanger (5), a first expansion valve (7, 52) , a first pump (11, 51) and a first evaporator (13, 54), characterized in that the first refrigerant is a liquid / vapor phase change fluid, and in that this installation comprises a reservoir (9, 70) whose lower part communicates with said first regulator (52) and with said first pump (11, 51), and whose upper part communicates with said first evaporator (13, 54) and said first compressor (3, 71).

2. Installation according to claim 1, characterized in that it further comprises a low temperature module (B) connected in cascade to said first heat exchanger (5).

3. Installation according to claim 2, characterized in that said low temperature module (B) comprises a second cooling circuit comprising a cold source (15) formed by a solid / liquid phase change material, and a third circuit cooling comprising means for cooling this material.

4. Installation according to claim 3, characterized in that the second cooling circuit comprises a storage unit (15) of said solid / liquid phase change material, and in that it carries a second cooling fluid circulating in a second pump (19), in a second heat exchanger (21), in a third heat exchanger (23), and in said first heat exchanger (5), then returning to said storage unit (15).

5. Installation according to one of claims 3 or 4, characterized in that said third cooling circuit conveys a third cooling fluid circulating in a second compressor (27) disposed downstream of the second heat exchanger (21), in a condenser (28), in a second regulator (31), then returning to said second heat exchanger (21).

6. Installation according to claim 5, characterized in that said third cooling fluid can be a synthetic cooling fluid of the hydro-fluorocarbon olefin type; hydro-fluoro-olefins, hydro-fluoro-carbides or carbon dioxide type R744.

7. Installation according to claim 1, characterized in that the very low temperature module (TB) comprises a condenser, the first heat exchanger and the condenser being arranged in the same storage unit (57).

8. Installation according to claim 7, characterized in that the very low temperature module (TB) comprises a tank configured to act as a liquid / vapor separator (60) connected on the one hand to the tank (70) and on the other hand to the storage unit (57) and a low pressure vapor / liquid bottle (50), the reservoir (70) being configured to convey said fluid from a pump (52) configured to circulate the fluid from the low pressure vapor bottle / liquid (50) to said storage unit (57), passing through the evaporator (54), to the vapor / liquid separator (60), said tank (70) being configured to have the function of a vessel of expansion in night mode.

9. Installation according to any one of claims 7 or 8, characterized in that it further comprises a low temperature module (B) connected in cascade or in direct delivery, on the one hand to said first compressor (71) by a first connection (72) and on the other hand to said low vapor / liquid pressure bottle (50) by a second connection (73).

10. Installation according to claim 9, characterized in that a second compressor (74) is understood and connected by pipes (1), on the one hand to the separator (60) and on the other hand to the first connection (72 ).

11. Installation according to any one of the preceding claims, characterized in that said first cooling fluid can be carbon dioxide of the R744 type, a synthetic cooling fluid of the hydro-fluoro-carbon type or of the hydro-fluoro type. -olefins.