EP0580848B1 - Cooling and heating device using a solid-gas reaction - Google Patents

Abstract

PCT No. PCT/FR93/00135 Sec. 371 Date Oct. 7, 1993 Sec. 102(e) Date Oct. 7, 1993 PCT Filed Feb. 10, 1993 PCT Pub. No. WO93/16339 PCT Pub. Date Aug. 19, 1993.A cooling and heating device using a chemical reaction comprising at least four reactors, each containing a salt capable of chemically reacting with a gas, an enclosure for receiving gas from the reactors and an enclosure for conveying gas to the reactors. The device is arranged so that, during the chemical reaction, two reactors are at the same higher pressure level, while two reactors are at the same lower pressure level. According to the invention, the device also comprises a heat-transporting fluid circuit for transferring heat between the reactors, operating at the same presure level.

Description

The present invention relates to a device for producing cold and / or heat by solid-gas reaction.

• on utilise pour le fonctionnement du système lui-même, l'énergie thermique ; l'énergie électrique n'est éventuellement utilisée que pour la circulation des fluides caloporteurs,
• on utilise, comme "moteur chimique" une réaction renversable entre un solide et un gaz du type :

The device targeted by the invention is based on the use of the so-called "thermochemical pump" system, the main characteristics of which are as follows:

• thermal energy is used for the operation of the system itself; electrical energy is possibly only used for the circulation of heat transfer fluids,
• a reversible reaction between a solid and a gas of the type is used as "chemical motor":

The reaction is exothermic in direction 1, which means that in this direction, it produces heat and endothermic in direction 2, that is to say that in this direction it produces cold.

Such a system allows energy storage in chemical form and has various fields of application.

In addition, such a system allows the production, from a heat source at the temperature Ts, of heat at the temperature Tu such that: $$\text{You <ts}$$

In this case, the system is called a "chemical heat pump".

Such a system also allows the production, from a heat source at temperature T's, of heat at temperature T'u such that: $$\text{You> You}$$

In this case, the system is called "chemical thermo transformer".

Thanks to this system, it is possible to produce cooling energy from a heat source and simultaneously produce, from a heat source at temperature T "s, heat at temperature T "u (T" u <T "s) and cooling energy.

Depending on the case, the use of the heat or cold produced is simultaneous with the consumption of energy at high temperature (Ts, T's, T "s) or delayed over time (storage effect).

Document EP-A-0.382.586 discloses a device for producing cold and / or heat by solid-gas reaction, comprising two reactors each containing a salt capable of reacting chemically with a gas, a condenser and an evaporator for gas. The elements of the device are arranged so as to allow the gas to follow a path from one reactor to another passing through the condenser and the evaporator. At the end of the chemical reaction, the gas-poor reactor is at a temperature higher than that of the reactor containing the gas which has just reacted with the salt, the two reactors being at different pressure levels. Heat is sent by a heat transfer system, from the reactor at the upper temperature to the reactor are at the lower temperature in order to increase the temperature of the latter. The chemical reaction then takes place in reverse, with part of the heat from one reactor serving as the heat source for desorption of the gas from the other reactor. This heat transfer between the two reactors serves to improve the efficiency of the system.

However, this improved system efficiency does not fully meet the business requirements for such a system.

Document US-A-5,025,635 describes a device intended to produce cold and / or heat comprising two sets of reactors, each set containing several blocks of reagent each block of which contains a different salt. The device further comprises a heat transfer circuit connecting the two assemblies through each block of reagent.

The present invention therefore aims to provide a device for the production of cold and / or heat by solid-gas reaction, in which the heat transfer between the various reaction chambers of the device is optimized.

To do this, the invention provides a device for producing cold and / or heat by chemical reaction comprising at least four reactors each containing a salt capable of reacting chemically with a gas, an enclosure intended to receive the gas from the reactors and an enclosure intended to deliver the gas to the reactors, the device being arranged so that, during the chemical reaction, two reactors are at the same higher pressure level and form a first assembly, and two reactors are at the same level of lower pressure and form a second assembly, the device further comprising a closed circuit of heat transfer fluid intended to transfer heat between the two assemblies, this circuit further comprising a cooler and a heating device for the heat transfer fluid, characterized in that the reactors at the same pressure level are arranged concentrically so that heat can pass between neighboring reactors only by conduction.

• les figures 1A et 1B sont chacune un diagramme de Clapeyron pour un premier type de dispositif,
• les figures 2A et 2B sont chacune une vue schématique du premier type de dispositif ,
• les figures 3A et 3B sont chacune un diagramme de Clapeyron pour un deuxième type de dispositif ,
• les figures 4A et 4B sont chacune une vue schématique du deuxième type de dispositif, ces deux types de dispositif étant décrits pour la bonne compréhension de l'invention, et
• la figure 5 est une vue schématique d'un dispositif selon l'invention.

The advantages, as well as the operation of the present invention, will appear more clearly on reading the following description given in a nonlimiting manner with reference to the appended drawings in which:

• FIGS. 1A and 1B are each a Clapeyron diagram for a first type of device,
• FIGS. 2A and 2B are each a schematic view of the first type of device,
• FIGS. 3A and 3B are each a Clapeyron diagram for a second type of device,
• FIGS. 4A and 4B are each a schematic view of the second type of device, these two types of device being described for a good understanding of the invention, and
• Figure 5 is a schematic view of a device according to the invention.

The operation of the device according to the invention is based on the reaction between a salt and a gas. As this is a real chemical reaction, we have a monovariant system at equilibrium, that is to say that there is a unique relationship between temperature and pressure in the form log P = A - B / T, expression in which P is the pressure, T the temperature in ° K and A and B are constants characteristic of the salt / gas couple used.

In the following description, the operating phases will be represented in a Clapeyron diagram as indicated in FIGS. 1A and 1B which include lines of equilibrium of the salts used.

In Figures 2A and 2B is shown a device for producing cold by solid-gas reaction. The device comprises four reaction chambers 10, 12, 14, 16, called reactors, formed of an enclosure containing a mixture of a salt and of expanded graphite, possibly recompressed. The device further comprises an evaporator 18 for the gas, as well as a condenser 20 which are arranged so as to be able to exchange heat with their environment.

The reactors 10 and 12 are connected, in the example illustrated in FIG. 2A, to the condenser 20 by conduits 22 and 24 which are provided with a valve 26 so as to be able to allow, selectively, the passage of gas between the reactors 10 , 12 and the condenser 20. Similarly, the reactors 14 and 16 are connected to the evaporator 18 by conduits 30 and 32 provided with a valve 34 so as to be able to allow, selectively, the passage of gas between the reactors 14 , 16 and the evaporator 18.

At a given point in the reaction cycle, the reactors 10, 12, 14, 16 are at the temperatures and pressures shown in the diagram in FIG. 1A. As can be seen from the diagram, the reactor 10 is at a temperature higher than that of the reactor 12, and the reactor 14 is at a temperature lower than that of the reactor 16.

Instead of transferring heat from a first reactor, at a high temperature and a low pressure level, to a second reactor at a lower temperature and a higher pressure level, heat transfer takes place between two reactors located at the same pressure level.

As shown in FIG. 2, the reactors 10, 12, 14, 16 are each provided with an associated heat exchanger 38, 40, 42 and 44, these exchangers being connected together by a conduit 46, in order to form a heat transfer circuit 45. A cooler 48 is mounted in the duct 46 between the reactors 12 and 14, and a heating device, for example a burner 50, is mounted in the duct 46 between the reactors 16 and 10.

During the implementation of the device, the gas passes through the conduits 22, 24 and 30, 32 between the reactors, the condenser 20 and the evaporator 18 in accordance with the cycle shown in FIG. 1A. At a given point in the cycle, the reactors 10, 12, 14 and 16 are at the temperatures and pressures illustrated in FIG. 1, the reactors 10 and 12 being at a high pressure and the reactors 14 and 16 being at a lower pressure. The heat transfer circuit 45 is put into operation, the heat transfer fluid circulating, under the effect of a pump (not shown) in the direction of the arrows 52.

Heat from reactor 10, which is at a temperature T _1, is sent to reactor 12 which is at a lower temperature T ₂ . The heat transfer fluid, cooled after its passage through the reactor 12, is then further cooled by the cooler 48 and leaves the latter at a temperature T ₃ . The cooled heat transfer fluid then passes through the reactor 14 and then through the reactor 16, which is at a temperature T4 before passing through the burner 50 in order to return to the starting temperature level T ₁ .

The reaction between the salts used in the reactors and the gas, which is for example ammonia, is reversible, the reactions in the two directions forming together a cycle. In order to complete a cycle, the reactors 10 and 12 are connected by conduits 52 and 54 to the evaporator 18 and the reactors 14 and 16 are connected to the condenser 20 by conduits 56 and 58 as shown in FIG. 2B. At the end of the reaction, the reactors 10 and 12 and the reactors 14 and 16 are in reversed positions with respect to those shown in FIG. 1A. The heat transfer circuit is then started in the opposite direction, as shown by the arrows 60 in FIG. 1B. The heat transfer effect caused by the passage of the heat transfer fluid is similar to that described above.

In FIGS. 4A and 4B is shown a second type of device for producing cold or heat by solid-gas reaction. This device differs from that of FIG. 2 in that the condenser 20 and the evaporator 18 have been replaced by reactors. The device thus comprises six reactors 80, 82, 84, 86, 88 and 90, four of which 82, 84, 88 and 90 are connected to a burner 92 and to a cooler 94 by a heat transfer circuit 96.

At a given instant in the reaction cycle, the reactors are at the temperatures and pressures illustrated in FIG. 3A, the reactors 80, 82 and 84 being at the same pressure level, but at different temperatures, the reactors 86, 88 and 90 being at the same lower pressure level, but also at different temperatures. The heat transfer circuit 96 is then put into operation, the heat transfer fluid circulating in the direction of the arrows 98. As was the case for the device in FIG. 2, the heat transfer fluid successively transfers the heat between the reactors 84 and 82 being at the higher pressure level, the reactors being at associated temperatures T ₁ and T ₂ . The heat transfer fluid then passes through the cooler 94 in order to reduce the temperature thereof to T ₃ before passing successively through the reactors 88 and 90, the temperature of the fluid increasing from T ₃ to T ₄ during this passage. As in the example in FIG. 1, the heat transfer fluid is then reheated in the burner 92 to a temperature T ₁ .

Analogously to that of the device in FIG. 1B, the reaction then takes place in the opposite direction, and, at a given instant in the cycle, the reactors are at the temperatures and pressures indicated in FIG. 3B. As shown in Figures 3B and 4B, the fluid coolant circulates in the opposite direction as indicated by the arrows 100.

Thus, during each stage of the reaction cycle, a heat transfer circuit ensures the transfer of heat between reactors being at the same high pressure level, the heat passing from a reactor being at a given temperature to a reactor at a lower temperature. As for reactors located at the same lower pressure level, the heat transfer fluid is heated during its passage through successive reactors, the heat transfer fluid passing from a reactor at a given temperature to a reactor at a higher temperature.

The devices of Figures 1 to 4 each include a heat transfer circuit for transferring heat from a first reactor to a second. FIG. 5 shows a device according to the invention, in which the heat passes from one reactor to another of the same series only by conduction, that is to say without having recourse to a heat transfer circuit between the reactors.

In this example, a cylindrical reactor 112 is arranged inside a first annular reactor 114, itself arranged inside a second annular reactor 116, the three reactors being arranged in order to ensure good conductivity thermal between them. A heat exchanger 118, connected to a heat transfer circuit shown schematically at 120 is disposed inside the cylindrical reactor 112. This set of three reactors 112, 114 and 116 is connected, in the example illustrated, to a second similar set which is formed by three reactors 122, 124 and 126. The heat transfer fluid, after passing through the heat exchanger 118, passes through another heat exchanger 128 which is in thermal communication with the reactor 116. The fluid then passes through a cooler 130, a heat exchanger 132 in thermal communication with the reactor 126, an exchanger 134 arranged inside the reactor 122, a burner 136 before passing through the exchanger 118. The operation of this type of device is similar to that of the device of FIGS. 3 and 4.

The performance of a device for producing cold and / or heat by solid-gas chemical reaction can be evaluated using the economic concept of the coefficient of performance or COP.

By way of example, the COP of a device corresponding to that of FIG. 2A is calculated.

In this example, reactors 12 and 14 each contain CaCl ₂ reacting with 4 moles of ammonia, ie CaCl ₂ .8NH ₃ to 4NH ₃ , reactors 10 and 16 each containing NiCl ₂ reacting with 4 moles of ammonia, or NiCl ₂ .6NH ₃ to 2NH ₃ .

The temperature of the heat transfer fluid leaving the burner 50 is 285 ° C, the temperature T3 is 35 ° C, and at the outlet of the evaporator is 5 ° C.

The COP defined by the ratio of the cold energies produced compared to the high temperature energy is equal to 1.07, since the heating or cooling of the heat transfer fluid in a reactor during absorption, or desorption of the gas corresponds to 80% of the maximum possible rise, or of the maximum possible reduction. This corresponds to the difference between the inlet temperature of the heat transfer fluid and the equilibrium temperature of the reactant at the pressure considered.

If, for the same device, the condenser is replaced by a reactor 80 containing BaCl ₂ (8-ONH ₃ ), and the evaporator is replaced by a reactor 86 containing the same salt, the COP is 1.60.

In each embodiment, heat is transferred between reactors located, at an instant in the cycle, at the same given pressure level. This heat transfer can be carried out by a heat transfer fluid or by simple conduction. The reactors located at the same pressure level can be connected to an associated heat transfer circuit or to a circuit which is common to all the reactors of the device.

The device according to the invention comprises two sets of reactors, each set being formed of several reactors and being intended to be connected to a condenser or to an evaporator. Alternatively, the condenser and evaporator can each be replaced by an associated reactor which is intended to receive or release the gas.

Claims (4)

1. Device for producing cold and/or heat by chemical reaction comprising at least four reactors each containing a salt which is capable of reacting chemically with a gas, a vessel intended to receive the gas from the reactors and a vessel intended to supply the gas to the reactors, the device being designed in such a manner that, during the chemical reaction, two reactors are at a higher pressure, and form a first assembly, and two reactors are at a lower pressure, and form a second assembly, the device furthermore comprising a closed circuit of heat-exchanging fluid intended to transfer heat between the two assemblies, this circuit furthermore comprising a cooler and a heating device for the heat-exchanging fluid, characterised in that the reactors having the same pressure are arranged in a concentric manner, in order that the heat may pass between the adjacent reactors purely by conduction.
2. Device according to Claim 1, characterised in that the vessel intended to receive the gas comprises a condenser, the vessel being intended to supply the gas comprising an evaporator.
3. Device according to Claim 1, characterised in that the vessel intended to receive the gas and the vessel intended to supply the gas each comprise a reactor.
4. Device according to one of CLaims 1 to 3 characterised in that each assembly comprises three reactors.

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