WO2022136281A1

WO2022136281A1 - Thermal management method for an ammonia storage system

Info

Publication number: WO2022136281A1
Application number: PCT/EP2021/086811
Authority: WO
Inventors: Jurgen Dedeurwaerder
Original assignee: Plastic Omnium Advanced Innovation And Research
Priority date: 2020-12-21
Filing date: 2021-12-20
Publication date: 2022-06-30
Also published as: FR3118154B1; EP4264025A1; FR3118154A1; JP2023551664A; KR20230107396A

Abstract

This ammonia storage system for a vehicle (2) is characterised in that it comprises: - at least one starter cartridge (8) for storing ammonia in absorbed form in a starter salt; - at least one main cartridge (10) for storing ammonia in absorbed form in a main salt, the starter salt having an ammonia desorption temperature greater than an ammonia desorption temperature of the main salt; - a heater (34) for heating the starter cartridge; - an ammonia consumption member (6); - at least one heat exchange fluid circulation line (22), which is arranged to allow a heat exchange between, on the one hand, the heat exchange fluid and, on the other hand, the starter cartridge (8), the main cartridges (10) and the member (6); and - an ammonia circulation pipe (12), which connects the starter cartridge (8), the main cartridges (10) and the member (6).

Description

Title of the invention: Process for thermal management of an ammonia storage system

The invention relates to thermal management in an ammonia storage system on board a vehicle. More particularly, the invention relates to an ammonia storage system for a vehicle and to a method for thermal management of such a system.

Ammonia can fulfill several functions on board a motor vehicle. Among the most widespread, mention may be made of its use as an energy carrier for a fuel cell operating directly with ammonia or else operating with dihydrogen, in which case the ammonia must be cracked before supplying the cell . We can also mention the catalytic reduction of exhaust gases in combustion engine vehicles.

In order to store ammonia on board the vehicle, it is known to store it in gaseous form absorbed in or adsorbed on a salt in storage cartridges. This is a safe method of storing ammonia. Ammonia must therefore be desorbed before it can be consumed. Document EP 2 181 963 B1 discloses an ammonia storage system according to the preamble of claim 8. For reasons of brevity, in the context of the description of the present invention, the terms absorb and desorb will be used to designate respectively the storage and release of gaseous ammonia on or from a salt, whether this storage takes place by absorption or adsorption.

Since the ammonia desorption reaction is endothermic, it is necessary to heat the storage cartridges in order to allow ammonia desorption. To this end, it is known to heat, for example using a heat transfer fluid, the cartridges when the vehicle needs to consume ammonia. Nevertheless, due to the inertia of the heat transfers necessary for the desorption of the ammonia in the cartridges, the ammonia may not be desorbed quickly enough, which may have adverse consequences on the operation of the vehicle, for example in the case where the ammonia is used to supply a fuel cell when the vehicle is started.

The object of the invention is in particular to remedy this problem by allowing rapid desorption of ammonia, in particular when the vehicle is started.

To this end, according to the invention, a thermal management method is provided in an ammonia storage system for a vehicle, in which the system comprises: - at least one cartridge, called a starter, for storing ammonia in the form absorbed in a salt, called a starter salt,

- at least one cartridge, called main, for storing ammonia in the form absorbed in a salt, called main salt, the starting salt having an ammonia desorption temperature higher than an ammonia desorption temperature of the main salt, at a given pressure,

- a heater arranged to heat the at least one starter cartridge so as to desorb the ammonia stored in the starter salt,

- an ammonia consumption unit, comprising for example a fuel cell,

- at least one heat transfer fluid circulation line arranged to allow an exchange of calories between, on the one hand, the heat transfer fluid, and, on the other hand, the at least one starter cartridge, the at least one cartridge main and ammonia consuming organ, and

- an ammonia circulation pipe connecting the at least one starter cartridge, the at least one main cartridge and the ammonia consumption unit, in which the following steps are implemented:

- in a start-up regime, the driver is activated to heat the at least one start-up cartridge, the circulation of heat transfer fluid is limited to the at least one start-up cartridge, and the heat transfer fluid is circulated in the line to heat the at least one main cartridge, then

- in a supply regime, the driver is deactivated, the heat transfer fluid is continued to circulate in the line to heat the at least one main cartridge and the ammonia is allowed to circulate in the pipe towards the at least a starter cartridge.

Thus the storage system comprises at least one starter cartridge equipped with a heater allowing rapid heating of this cartridge and rapid desorption of ammonia to supply the consumer unit while the at least one main cartridge begins to desorb ammonia.

During the feed regime, part of the ammonia released by the at least one main cartridge is used to fill the at least one starter cartridge. Indeed, the heater having been deactivated, the temperature in the at least one starter cartridge drops below the desorption temperature of the starter salt during the supply regime, in particular thanks to the circulation of heat transfer fluid which presents during the feed regime a temperature between the ammonia desorption temperature of the main salt and that of the starting salt at given pressure. The starter salt of the at least one starter cartridge can then absorb the ammonia coming from the at least one main cartridge. Thus, the at least one starter cartridge is operational for the next start of the vehicle.

Furthermore, the fact that, during the supply regime, the heat transfer fluid is configured to both heat the at least one main cartridge and cool the at least one starter cartridge, allows the calories supplied by the driver to the at least one starter cartridge during the start-up regime to be redistributed by the heat transfer fluid to the at least one main cartridge during the supply regime. The energy balance of the thermal management process is thus optimized.

Advantageously, the at least one starter cartridge has an ammonia storage capacity lower than an ammonia storage capacity of the at least one main cartridge.

This further accelerates the desorption of ammonia in the at least one starter cartridge.

Advantageously, the ammonia storage system further comprises a pressure sensor in the ammonia circulation pipe, and the transition from the start-up regime to the supply regime is carried out when the pressure sensor measures a higher ammonia pressure at a predetermined threshold, for example 2 or 3 bar.

The change in speed can thus be controlled according to the measurements of the pressure sensor, which is simple to set up.

Advantageously, the following step is also implemented:

- in a peak supply regime, the driver is activated to heat the at least one starter cartridge, the circulation of the heat transfer fluid to the at least one starter cartridge is limited, and the fluid continues to circulate coolant in the line to heat the at least one main cartridge.

The invention thus also makes it possible to be able to respond to a momentary peak in ammonia consumption by the consumer organ. In other words, the at least one starter cartridge serves both as a buffer for starting the vehicle and as an additional ammonia reservoir which can release ammonia very quickly.

Advantageously, the driver comprises an induction heater.

This type of heater is suitable for rapidly heating the at least one starter cartridge.

Advantageously, the starter salt comprises magnesium chloride or manganese chloride or a mixture thereof. Advantageously, the main salt comprises calcium chloride or strontium chloride or a mixture of these.

These salts have desorption temperatures that are sufficiently far apart, which makes it possible to increase the efficiency of heat transfer between the heat transfer fluid and the cartridges, whether for cooling the at least one starter cartridge or for heating the at least one main cartridge.

According to one embodiment of the invention, during the supply regime, the heat transfer fluid is also circulated in the at least one starter cartridge to cool it, the heat transfer fluid having a temperature between the desorption temperature ammonia temperature of the main salt and the ammonia desorption temperature of the starting salt at the given pressure.

The heat transfer fluid can thus simultaneously, during the supply regime, cool the at least one starter cartridge so that it can absorb ammonia with a view to the next start-up or the next consumption peak, and heat the au least one main cartridge for desorbing the ammonia in order to supply the ammonia consumer unit. This makes it possible to simplify the organization of heat transfers in the storage system, and therefore to simplify the structure of this system and in particular of the line of circulation of the heat transfer fluid. In addition, it is understood that the thermal energy supplied to the at least one starter cartridge by the driver during the start-up regime is not lost since it is used to heat the heat transfer fluid during the supply regime which goes itself heat the at least one main cartridge. This therefore optimizes the energy consumption of the storage system.

According to another embodiment of the invention, the ammonia storage system comprises:

- a first heat transfer fluid circulation line, arranged to allow an exchange of calories between the heat transfer fluid and the at least one starter cartridge, and

- a second heat transfer fluid circulation line, arranged to allow an exchange of calories between, on the one hand, the heat transfer fluid, and, on the other hand, the at least one main cartridge and the consumer member of ammonia, the ammonia storage system further comprising a heat exchanger arranged to allow an exchange of calories between the heat transfer fluid of the first line and the heat transfer fluid of the second line, preferably without mixing the heat transfer fluids of the two lines .

The invention thus allows the separate thermal management of the at least one starter cartridge and the at least one main cartridge, while avoiding losses thermal energy through the heat exchanger. In addition, it is understood that the thermal energy supplied to the at least one starter cartridge by the driver during the start-up regime is not lost since it is used to heat the heat transfer fluid of the first line during the start-up regime. supply which will itself heat the heat transfer fluid of the second line, by means of the heat exchanger, and therefore indirectly the at least one main cartridge. This therefore makes it possible to optimize the energy consumption of the storage system.

Advantageously, the method is implemented on board a vehicle.

There is also provided according to the invention an ammonia storage system for a vehicle which comprises:

- at least one cartridge, called starter, for storing ammonia in the form absorbed in a salt, called starter salt,

- an ammonia-consuming organ,

- an ammonia circulation line connecting the at least one starter cartridge, the at least one main cartridge and the ammonia consumption device.

Advantageously, the storage system further comprises a control unit arranged to implement a thermal management method as described above.

According to one embodiment of the invention, the heater comprises a pipe made of an electrically conductive material, preferably a ferromagnetic material, the pipe being configured to:

- be heated by induction, and

- form a section of the heat transfer fluid circulation line.

Preferably, the outer part of the at least one starter cartridge forming the container, in other words the casing of the at least one starter cartridge starting, is made of a material that cannot be heated by induction, such as plastic.

There is also provided according to the invention a motor vehicle comprising an ammonia storage system as described in the foregoing.

Brief description of figures

The invention will now be presented in support of the following description given solely by way of example and made with reference to the appended drawings in which:

[Fig. 1] Figure 1 is a diagram illustrating an ammonia storage system for a vehicle according to a first embodiment of the invention,

[Fig. 2] Figure 2 is an enlarged general view of a starter cartridge of the ammonia storage system of Figure 1, and

[Fig. 3] Figure 3 is a diagram illustrating an ammonia storage system for a vehicle according to a second embodiment of the invention.

detailed description

There is shown in Figure 1 an ammonia storage system 2 for a vehicle 4 according to a first embodiment of the invention.

The ammonia storage system 2 comprises an ammonia consumption member 6. This is a member of the vehicle 4 which must be supplied with ammonia in order to operate. It can be an ammonia-type fuel cell, or a hydrogen-type fuel cell with a cracking module configured to crack ammonia into a gas mixture comprising dihydrogen. It may also be a component for catalytic reduction of the vehicle's exhaust gases. Since these different types of ammonia-consuming organs are known, they will not be described further in what follows.

The ammonia storage system 2 comprises at least one cartridge, called a starter cartridge 8, for storing ammonia in the form absorbed in a salt, called a starter salt. The ammonia storage system 2 here comprises a single starter cartridge 8, but provision can be made for the ammonia storage system to comprise several starter cartridges, for example two or more. The starter cartridge 8 allows the storage of ammonia in gaseous form. To this end, the starter cartridge 8 comprises a matrix carrying the starter salt, the ammonia being absorbed in the starter salt. Here, the starter salt includes magnesium chloride or manganese chloride or a mixture thereof. The ammonia storage system 2 comprises at least one cartridge, called the main cartridge 10, for storing ammonia in the form absorbed in a salt, called the main salt. The ammonia storage system 2 here comprises two main cartridges 10, but provision can be made for the ammonia storage system to comprise a higher number of main cartridges. The main cartridges 10 allow the storage of ammonia in gaseous form. For this purpose, the main cartridges 10 each comprise a matrix carrying the main salt, the ammonia being absorbed in the main salt. Here, the main salt includes calcium chloride or strontium chloride or a mixture thereof. The starter salt has an ammonia desorption temperature Td greater than an ammonia desorption temperature of the main salt T _p , at a given pressure, for example 2 or 3 bar. The interest of this property will be explained later.

The ammonia storage system 2 comprises an ammonia circulation line 12 connecting the starter cartridge 8, the main cartridges 10 and the ammonia consumer unit 6. The ammonia circulation line 12 allows the the ammonia released by the starter cartridge 8 and the main cartridges 10 to be routed to the ammonia consumer unit 6.

The ammonia circulation pipe 12 comprises a metering unit 14 which makes it possible to meter the quantity of ammonia which is conveyed from the cartridges 8, 10 in the direction of the ammonia consumption member 6. The circulation pipe of ammonia 12 further comprises a pressure sensor 16 which allows the measurement of the ammonia pressure in the ammonia circulation line 12.

The ammonia circulation line 12 comprises, at the ammonia outlet of the starter cartridge 8, an on/off valve 18a configured to be electrically controllable. The on/off valve 18a can occupy an open position in which it allows the passage of ammonia through the valve in both directions, and a closed position in which it prevents the passage of ammonia through the valve in both directions. .

The ammonia circulation line 12 comprises a passive valve 20 at the ammonia outlet of each of the main cartridges 10. By the term “passive”, it is meant that the valve operates without being supplied with energy and without being controlled by a component. meant for that purpose. Each passive valve 20 is configured to prevent the ammonia present in the ammonia circulation line 12 from entering the main cartridge 10 to which it is connected. Each passive valve 20 is configured to allow the passage of ammonia from the main cartridge 10 to which it is connected to the ammonia circulation line 12 when the ammonia pressure in said main cartridge 10 is high enough.

The ammonia storage system 2 comprises a heat transfer fluid circulation line 22 arranged to allow an exchange of calories between, on the one hand, a heat transfer fluid, and, on the other hand, the starter cartridge 8, the cartridges main 10 and the ammonia consumer member 6. In Figure 1, the arrows indicate the direction of circulation of the heat transfer fluid in the circulation line 22.

The heat transfer fluid circulation line 22 comprises a valve with four ports 24 delimiting four sections. The first section 26 corresponds to the coolant fluid outlet of the ammonia consuming member 6. The second section 28 corresponds to the coolant fluid inlet of the starter cartridge 8. The third section 30 corresponds to the inlet in heat transfer fluid from the main cartridges 10. For each main cartridge 10, the third section 28 comprises an all-to-nothing valve 18b configured to be electrically controllable. The third section 30 is further supplied by the heat transfer fluid outlet of the starter cartridge 8. The fourth section 32 corresponds to a heat transfer fluid inlet of the ammonia consuming member 6. The fourth section 32 is furthermore powered by the heat transfer fluid outlet of the main cartridges 10.

Figure 2 illustrates the arrangement of starter cartridge 8 in ammonia storage system 2. As shown in this figure, ammonia storage system 2 includes a heater 34 configured to heat the starter cartridge 8 so as to desorb the ammonia stored in the starting salt. The heater 34 is here an induction type heater. It comprises a pipe 36 made of an electrically conductive material, here a ferromagnetic material, connected to an alternating current source 38. The pipe 36 is wound in the form of turns around the starter cartridge 8. By heating the pipe 36 in a manner known per se, the starter cartridge 8 is also heated. An outer casing of the starter cartridge 8 is made of plastic so that it is not heated by induction. Hose 36 is connected to a coolant supply configured to cool Hose 36 when it ceases to be heated by induction.

According to a particular embodiment of the invention, the pipe 36 is connected to the heat transfer fluid circulation line 22 so that it forms a section thereof. The pipe 36 then forms both a heat source, by induction, and a heat exchanger, as a section of the heat transfer fluid circulation line 22. In other words, the heater 34 can also provide calories to Starter Cartridge 8 than absorbing calories from Starter Cartridge 8. This contributes to reduce the number of elements constituting the ammonia storage system 2 and therefore to facilitate its design as well as to reduce its manufacturing cost.

The ammonia storage system 2 comprises a control unit 40 configured to control the operation of the elements of the ammonia storage system 2, in particular that of the metering unit 14, the on/off valves 18a, 18b and the driver 34.

We will now describe a method of thermal management of the ammonia storage system 2 which is implemented by the control unit 40 on board the vehicle 4.

It is assumed that vehicle 4 is initially stationary. When turned on, the process begins with a start-up regime.

During the starting regime, the heater 34 is activated so as to heat the starting cartridge 8 and the starting salt in which ammonia is absorbed. During this heating, the circulation of heat transfer fluid to the starter cartridge 8 is limited so as not to cool it unnecessarily. With heating, the starter salt eventually reaches its ammonia desorption temperature T _d . The starter salt then begins to desorb the ammonia. During the start-up regime, the on/off valve 18a is opened so that the ammonia desorbed from the start-up salt can exit from the start-up cartridge 8 to supply the ammonia circulation line 12. The metering unit 14 doses the amount of this ammonia that is supplied to the ammonia consuming organ 6.

During the start-up regime, the all-or-nothing valves 18b are open, and the heat transfer fluid is circulated in the circulation line 22 to heat the main cartridges 10. The heat transfer fluid initially has a low temperature, but as the member 6 consumes ammonia, the latter releases heat which is absorbed by the heat transfer fluid, which then rises in temperature. Under these conditions, the heat transfer fluid heats the main cartridges 10 more slowly than the heater 34 heats the starter cartridge 8, so that ammonia is first desorbed from the starter cartridge 8.

During the start-up regime, the heat transfer fluid continues to heat the main cartridges 10, so that the main salt of the main cartridges 10 ends up reaching its ammonia desorption temperature T _p . The starter salt then begins to desorb the ammonia. This desorbed ammonia exits the main cartridges 10 and passes through the passive valves 20 to feed the ammonia circulation line 12, which raises the ammonia pressure in the ammonia circulation line 12.

During the starting regime, the member 6 is mainly supplied with ammonia by the starting cartridge 8. Once the pressure sensor 16 measures an ammonia pressure greater than a predetermined threshold, for example 2 or 3 bar, the start-up regime is changed to a supply regime.

During the supply regime, the heater 34 is deactivated and the heat transfer fluid is circulated to the starter cartridge 8. At this time, the temperature of the heat transfer fluid T _f is between the ammonia desorption temperature of the main salt T _p and the ammonia desorption temperature of the starting salt T _d . The heat transfer fluid thus makes it possible to cool the starter cartridge 8, so that the starter salt ceases to desorb ammonia. It is thus understood that the fact that the starter salt has an ammonia desorption temperature Td higher than the ammonia desorption temperature of the main salt T _p makes it possible both to cool the starter cartridge 8 and the main cartridges 10 with the same heat transfer fluid.

During the supply regime, the all-or-nothing valve 18a is kept open so that ammonia coming from the main cartridges 10 can fill the starter cartridge 8. The drop in temperature of the starter salt thanks to the heat transfer fluid allows it to to absorb ammonia. The on/off valve 18a is closed when the starter cartridge 8 has absorbed enough ammonia. Starter cartridge 8 will thus be ready to release ammonia, for example for the next start of vehicle 4.

During the supply regime, the heat transfer fluid continues to circulate in the circulation line 22 to heat the main cartridges 10 so that they continue to release ammonia as long as the member 6 needs it, this management being controlled by the control unit 40 and the metering unit 14.

During the feeding regime, the 6 organ is mainly supplied with ammonia from the 10 main cartridges.

In the case where the member 6 has an ammonia consumption peak, a peak supply regime is implemented, in which the heater 34 is activated so as to heat the starter cartridge 8, which has been recharged in ammonia during the feeding regime. During this heating, the circulation of heat transfer fluid to the starter cartridge 8 is limited so as not to cool it unnecessarily. With heating, the starter salt eventually reaches its ammonia desorption temperature Td. The starter salt then begins to desorb the ammonia. During the peak supply regime, the on/off valve 18a is opened so that the ammonia desorbed from the starter salt can exit from the starter cartridge 8 to feed the ammonia circulation line 12. The unit metering 14 meters the amount of this ammonia which is supplied to the consumer organ of ammonia 6. During the peak supply regime, the main cartridges 10 are heated by the heat transfer fluid in the same way as during the supply regime. Thus, during the peak supply regime, the member 6 is supplied with ammonia both by the starter cartridge 8 and the main cartridges 10.

FIG. 3 shows an ammonia storage system 2′ according to a second embodiment of the invention.

The ammonia storage system 2' differs from that of the first mode in that the heat transfer fluid circulation line 22 comprises a first heat transfer fluid circulation line 22a, arranged to allow an exchange of calories between the heat transfer fluid and the starter cartridge 8, and a second heat transfer fluid circulation line 22b, arranged to allow an exchange of calories between, on the one hand, the heat transfer fluid, and, on the other hand, the main cartridges 10 and the consumption of ammonia 6. The circulation of the heat transfer fluid in the first line 22a is ensured by a pump 42. The ammonia storage system 2' also comprises a heat exchanger 44 configured to allow an exchange of calories between the fluid heat transfer fluid from the first line 22a and the heat transfer fluid from the second line 22b without there being any mixing of the heat transfer fluids from the two lines 22a, 22b.

The ammonia storage system 2' includes a three-port valve 25 which replaces the four-port valve of the ammonia storage system of the first embodiment. The second port is in effect replaced by the heat exchanger 44. The remaining three ports are configured in the same way as in the first embodiment.

The ammonia storage system 2' comprises a control unit 40 configured to implement a thermal management method of the ammonia storage system 2' similar to that of the first embodiment.

The invention is not limited to the embodiments shown and other embodiments will be apparent to those skilled in the art.

In particular, a temperature sensor can be provided in the heat transfer fluid circulation line(s) to ensure that the temperature of the heat transfer fluid(s) T _f remains between the ammonia desorption temperature of the main salt T _p and the temperature of ammonia desorption from the starting salt T _d during the feeding regime.

In each of the embodiments, means other than the pressure sensor can be used to determine the moment of passage from the starting regime to the supply regime. For example, a pre-established chart of data from the ammonia storage system can be used as a reference to determine the moment to make the transition from the start-up regime to the feed regime. way more In general, any means or any method making it possible to measure, directly or indirectly, the quantity of ammonia in the ammonia circulation line is suitable for determining the moment for making the transition from the start-up regime to the supply regime.

List of references

2; 2': ammonia storage system

4: vehicle

6: organ of ammonia consumption

8: starter cartridge

10: main cartridge

12: ammonia circulation line

14: dosing unit

16: pressure sensor

18a, 18b: on/off valve

20: passive valve

22: heat transfer fluid circulation line

22a: first heat transfer fluid circulation line

22b: second heat transfer fluid circulation line

24: four-port valve

25: three-port valve

26: first section

28: second section

30: third section

32: fourth section

34: driver

36: pipe

38: alternating current source

40: control unit

42: pump

44: heat exchanger

Claims

[Claim 1] Thermal management method in an ammonia storage system (2; 2') for a vehicle, characterized in that the system comprises:

- at least one cartridge, called starter (8), for storing ammonia in the form absorbed in a salt, called starter salt,

- at least one cartridge, called the main cartridge (10), for storing ammonia in the form absorbed in a salt, called the main salt, the starting salt having an ammonia desorption temperature higher than an ammonia desorption temperature of the main salt, this at a given pressure,

- a heater (34) arranged to heat the at least one starter cartridge (8) so as to desorb the ammonia stored in the starter salt,

- an ammonia consuming organ (6),

- at least one heat transfer fluid circulation line (22) arranged to allow an exchange of calories between, on the one hand, the heat transfer fluid, and, on the other hand, the at least one starter cartridge (8), the at least one main cartridge (10) and the ammonia consumer (6), and

- an ammonia circulation pipe (12) connecting the at least one starter cartridge (8), the at least one main cartridge (10) and the ammonia consumption member (6), in which implements the following steps:

- in a starting regime, the driver (34) is activated to heat the at least one starter cartridge (8), the circulation of heat transfer fluid to the at least one starter cartridge (8) is limited, and circulates the heat transfer fluid in the line (22) to heat the at least one main cartridge (10), then

- in a supply regime, the heater (34) is deactivated, the heat transfer fluid is continued to circulate in the line (22) to heat the at least one main cartridge (10) and the circulation of the ammonia in the line (12) to the at least one starter cartridge (8).

[Claim 2] Thermal management method according to the preceding claim, in which the ammonia storage system (2; 2') further comprises a pressure sensor (16) in the ammonia circulation pipe (12) , the transition from the start-up regime to the supply regime is carried out when the pressure sensor (16) measures an ammonia pressure greater than a predetermined threshold, for example 2 or 3 bar.

[Claim 3] Thermal management method according to any one of the preceding claims, in which the following step is implemented:

- in a peak supply regime, the driver (34) is activated to heat the at least one starter cartridge (8), the circulation of the heat transfer fluid to the at least one starter cartridge (8) is limited , and the heat transfer fluid continues to circulate in the line (22) to heat the at least one main cartridge (10).

[Claim 4] A thermal management method according to any preceding claim, wherein the heater (34) comprises an induction heater.

[Claim 5] Thermal management method according to any one of Claims 1 to 4, in which during the supply regime, the heat transfer fluid is also circulated in the at least one starter cartridge (8) for the cooling, the heat transfer fluid having a temperature between the ammonia desorption temperature of the main salt and the ammonia desorption temperature of the starting salt at the given pressure.

[Claim 6] Thermal management method according to any one of claims 1 to 4, in which the ammonia storage system (2') comprises:

- a first heat transfer fluid circulation line (22a), arranged to allow an exchange of calories between the heat transfer fluid and the at least one starter cartridge (8), and

- a second heat transfer fluid circulation line (22b), arranged to allow an exchange of calories between, on the one hand, the heat transfer fluid, and, on the other hand, the at least one main cartridge (10) and the ammonia consuming organ (6), - 15 - the ammonia storage system (2 ') further comprising a heat exchanger (44) arranged to allow an exchange of calories between the heat transfer fluid of the first line (22a) and the heat transfer fluid of the second line (22b), preferably without mixing the heat transfer fluids of the two lines.

[Claim 7] Thermal management method according to any one of the preceding claims, implemented on board a vehicle (4).

[Claim 8] Ammonia storage system for a vehicle (2; 2'), characterized in that it comprises:

- at least one cartridge, called main (10), for storing ammonia in the form absorbed in a salt, called main salt,

- a heater (34) arranged to heat the at least one starter cartridge so as to desorb the ammonia stored in the starter salt,

- an ammonia consuming organ (6), and

- an ammonia circulation line (12) connecting the at least one starter cartridge (8), the at least one main cartridge (10) and the ammonia consumption member (6), characterized in that that it also includes:

- at least one heat transfer fluid circulation line (22) arranged to allow an exchange of calories between, on the one hand, the heat transfer fluid, and, on the other hand, the at least one starter cartridge (8), the at least one main cartridge (10) and the ammonia consumer (6), and in that the starting salt has an ammonia desorption temperature higher than an ammonia desorption temperature of the salt principal, this at a given pressure.

[Claim 9] Ammonia storage system (2; 2') according to the preceding claim, further comprising a control unit (40) arranged to implement a thermal management method according to any one of claims 1 to 7.

[Claim 10] Ammonia storage system (2) according to claim 8 or 9, wherein the heater (34) comprises a pipe (36) made of - 16 - an electrically conductive material, preferably a ferromagnetic material, the pipe (36) being configured to:

- be heated by induction, and

- form a section of the heat transfer fluid circulation line (22).

[Claim 11] Motor vehicle (4) comprising an ammonia storage system (2; 2') according to any one of Claims 8 to 10.