EP0317597A1 - Method and device for producing cold by solid-gas reaction - Google Patents

Abstract

The device comprises at least one reactor (R), a condenser (C), a gas collector (Co) and an evaporator (E). The following simultaneous reactions are carried out in the reactor (R): <X,mNH3> + n(NH3) -> X, (m+n)NH3>; n[NH3] -> n(NH3); then <X,(m+n)NH3> -> <X,mNH3> = n(NH3); n(NH3) -> n[NH3]; the symbols < >, [ ], ( ) designating respectively the solid, liquid and gaseous states, X being chosen from ZnCl2, CuSO4, CuCl, LiBr, LiCl, ZnSO4, SrCl2, MnCl2, FeCl2 , MgCl2, CaCl2 and NiCl2, m and n being numbers such that: m=3, n=1 if X = ZnSO4; m=4, n=1 if X = CuSO4; m=0, n=1 if X = LiCl, SrCl2; m=1, n=1 if X = LiCl, CaCl2; m=2, n=2 if X = ZnCl2, CuSO4; m=1, n=0.5 if X = CuCl; m=2, n=1 if X = LiBr, ZnSO4; m=2, n=4 if X = MnCl2, FeCl2, NiCl2; m=4, n=2 if X = MgCl2. Use to produce cold between +10°C and -40°C, particularly in transport vehicles.

Description

"Process for producing cold by solid-gas reaction and device relating thereto"

The present invention relates to a method for producing cold by solid-gas reaction.

The invention also relates to the device for implementing this method. Currently, cold production installations almost exclusively involve the compression cycle (compressor - condenser - expansion valve - evaporator).

The advantages of these installations lie mainly in the fact that they use a very well-known and proven technique, and make it possible to obtain a good yield (about 2 in air conditioning), 1.5 to 0 ° C., less than 1 for very low temperatures).

The drawbacks of these installations are linked to the presence of the compressor, which poses maintenance problems, and of course to the obligation to have mechanical power (generally in electrical form).

The absorption cycle is based on the affinity of one fluid for another. Such a cycle includes an evaporator, an absorber, a separator boiler, a condenser and a pressure reducer.

For low temperatures, the generally accepted formula is the ammonia / water solution. The advantage of the absorption cycle is that it only requires thermal energy (heat rejection, gas, lean gas, etc.) and that it does not use essential mechanical parts.

The disadvantages of this cycle are: yield fairly weak (less than 0.5-0.8) and the fact that it requires the circulation of a large amount of solution.

The other known cold production devices are gas expansion (air conditioning of aircraft), ^{** •} the Peltier effect as well as the solid sorption systems which are described below.

Solid-gas systems involve absorption or reaction phenomena. These are mainly the following systems: - ** ^• * • - - the water zeolite system (Z water), limited to a temperature above 0 ° C,

- the activated carbon-m thanol system (CA-methanol)

- hydride systems

- salt / ammonia systems or ammonia derivatives.

The development of the first three systems above encountered the following difficulties:

- low energy density (Z-water, CA-methanol)

- rare products and presence of hydrogen (Hydrides) 20 - system under very reduced pressure (Z-water)

- management difficulties for divider systems (Z-water, CA-methanol).

The development of salt / ammonia or derivative systems has long been hampered by the low powers 2 obtained. Studies carried out on transfers (of mass and heat) and on kinetic-transfer couplings, have led to the search for a binder making it possible to improve these transfers. The research carried out made it possible to produce reaction mixtures which under certain conditions lead to powers of several kW / kg of salt. This level of power makes it possible to design systems whose performance is comparable to conventional compression systems currently used.

The principle of the system for producing cold by solid-gas reaction will be recalled below. Certain solids can, under given conditions of temperature and pressure, react with certain gases; this reaction results in the formation of a defined chemical compound, generally solid, and is accompanied by the release of heat. When, under other conditions of temperature and pressure, heat is supplied to the compound thus formed, there is a release of the gas and the formation of the original solid product.

The operation of the system is therefore carried out in two phases shifted in time, illustrated by FIG. 1 and explained below: In the first phase called "phase of evaporatio synthesis", there is simultaneously evaporation of a refrigerant and reaction with the solid of the gas thus formed:

[G] liq. => • (G) gas <S> + (G) = ^* »<S, G> (I)

The fluid FI supplies the heat ΔHL to the evaporator E. The liquid [G] evaporates and the gas formed will become fixed in the reactor R on the solid <S> to give the compound <S, G>. The reaction is accompanied, within reactor R, by a release of heat AHR, this being evacuated by the fluid F2. The cold source is therefore the evaporator E, the cold being used directly or indirectly from the fluid FI.

In the second phase, called "decomposition - condensation phase", the solid <S, G> is simultaneously decomposed, with release of the gas (G), in reactor ^' R and condensation of (G) in condenser C:

<S, G> 5 "- <S> + (G)

(G) gas s "- [G] liq.

The heatΔH is supplied to the solid ^“ S, G> contained in the reactor R by the fluid F3 (or the fluid F2 used previously). Under the effect of heat, the gas (G) is released and will condense at C, the condensation s ^r accompanying the release of heat ΔHL, this being evacuated by the fluid F4.

The thermodynamic characteristics of the system used are as follows:

As we are in the presence of a real chemical reaction between a solid and a gas, we have a monovariant system at equilibrium, that is to say that there is a unique relationship between the temperature and the pressure of the form: Log P = A - B / T

expression in which P is the pressure, T the temperature (expressed in degrees K) A and B being constants characteristic of the solid / gas couple used. The two operating phases can be represented in a pressure / temperature diagram, as shown in figure 2. In this figure 2, (I) is the equilibrium line

(G) ^ [G] and

(J) is the equilibrium line <S> + (G) 5 * ^* - <S, G>

The equilibrium line (I) determines two zones in which there is either condensation or evaporation of the compound (G). The equilibrium line (J) determines two zones in which there is either synthesis, from <S> and <G>, of the compound <S, G>, or decomposition of the solid <S, G> with release from (G).

During the evaporation-synthesis phase, [G] evaporates at the temperature TE and will react with the solid <S> which is at the temperature TA. This temperature TA is such that the operating point of the solid (point P) is in the synthesis zone. This phase is carried out at pressure PB.

During the decomposition-condensation phase, the compound <S, G> is at a temperature TD such that the operating point of the solid (point Q) is in the decomposition. The compound (G) released will condense at temperature TC. This phase is carried out at pressure PH such that PH greater than PB.

None of the solid-gas reactions currently known makes it possible to produce cold down to -40 ° C., the maximum temperature outside the enclosure being + 30 ° C. and at the same time to produce cold up to + 10 ° C, the maximum temperature outside the enclosure being + 80 ° C. A reaction which makes it possible to obtain these temperatures would be particularly well suited to the production of an industrial device for producing cold in vehicles for transporting products, such as frozen food products or products kept at low temperature.

The object of the present invention is precisely to achieve this objective.

The process targeted by the invention makes it possible to produce cold by means of a device comprising a reactor which contains a solid compound capable of reacting with a gas according to an exothermic reaction, this reactor being connected to a condenser, a gas collector and an evaporator which is in heat exchange relation with an enclosure to be cooled, the interior of the reactor being in heat exchange relation with an external heat source.

According to the invention, this process is characterized in that • the following simultaneous reactions are carried out in the reactor: <X, mNH ₃ > + n (NH ₃ ) ^' -J><X, (m + n) NH ₃ > n [NH ₃ ] rs * n (NH ₃ ) then <X, (m + n) NH ₃ > -XX, mNH ₃ >'+ n (NH ₃ ) n (NH ₃ ) * n [NH ₃ ]

X being chosen from ZnCl ₂ , CuS0, CuCl, LiBr, LiCl, ZnS0 ₄ , SrClz, MnCl ₂ , FeCl ₂ , MgCl∑, ^* CaCl2 and NiCl2, m and n being numbers such as: m = 3, n≈l if X = ZnS0 ₄ m = 0, n≈l if X = LiCl, SrCl ₂ m≈l, n≈l if X = LiCl, CaCl ₂ m = 2, n = 2 if X = ZnCl ₂ , CuS0 m≈l, n = 0, 5 if X = CuCl m = 2, n≈l if X = LiBr, ZnS0 ₄ m = 2, n = 4 if X = MnCl ₂ , FeCl ₂ , NiCl ₂ m = 4, n = 2 if X = MgCl ₂

The symbols <>, [], () above denote respectively a compound in the solid state, in the liquid state and in the gaseous state.

Thus if one wants to produce cold down to -40 ° C in the enclosure to be refrigerated, the maximum temperature outside thereof being at most equal to 30 ° C, the deviation from point O ( Figure 2) relative to the equilibrium line J being 20 ° C and the condensing temperature being 35 ° C, an external heat source is used, the temperature is greater than an h value such that:

if X = ZnCl ₂ (m = 2, n = 2) Th = 139 ° C if X = CuS0 ₄ (m = 4, n≈l) Tu = 145 ° C if X = CuCK ≈l, n = 0.5 ) Th = 151 ° C if X = LiBr (m = 2, n≈l) Th = 155 ° C if X = LiCl (m≈l, n≈l) Th = 167 ° C if X = ZnS0 ₄ (m = 3, n≈l) Th = 173 ° C if X = SrCl ₂ (m = 0, n≈l) Th = 173 ° C if X = MnClz (m = 2, n = 4) Th = 174 ° C if X = LiCKm≈O, n≈l) Th = 203 ° C if X = FeCl ₂ (m = 2, n = 4) Th = 208 ° C if X = MgCl ₂ (m = 4, n = 2) Th = 217 ° C if X = CuSO <(m = 2, n = 2) Th = 230 ° C if X = ZnS0 ₄ (m = 2, n≈l) Th = 247 ° C if X = CaCl ₂ (m≈l, n≈l) Th = 265 ° C if X = NiCl ₂ (m = 2 _r n = 4) Th = 282 ° C

Furthermore, if it is desired to produce cold up to + 10 ° C in the enclosure to be refrigerated, the maximum temperature outside thereof being at most equal to + 80 ° C, the difference in point Q (Figure 2) with respect to the equilibrium line J being 20 ° C and the condensation temperature being 85 ° C, an external heat source is used whose temperature is higher than a value Th such that:

if X = ZnCl ₂ (m = 2, n = 2) Th = 162 ° C if X = CuS0 ₄ (m = 4, n≈l) Th = 170 ° C if X = CuCl (m≈l, n = 0.5) TThh = 180 ° C if X = LiBr (m = 2, n≈l) Th = 196 ° C if X = ZnS0 ₄ (m = 3, n≈ l) Th = 200 ° C if X = LiCl (m≈l, n≈l) Th = 208 ° C if X = MnCl ₂ (m = 2, n = 4) Th = 212 ° C if X = SrCl ₂ ( m≈O, n≈l) T Thh = = 217 ° C if X = LiCl (m≈O, n≈l) Th = 249 ° C if X = FeCl ₂ (m = 2, n = 4) Th = 256 ° C if X = MgCl ₂ (m = 4, n = 2) Th = 256 ° C if X = CuS0 ₄ (m = 2, n = 2) Th = 265 ° C if X = ZnS0 ₄ (m = 2, n≈l) Th = 282 ° C if X = CaCl ₂ (m≈l, n≈l) Th = 311 ° C if X = NiCl ₂ (m = 2, n = 4) Th - 338 ° C

The invention also relates to a device for producing cold at a temperature between - 40 ° C and + 10 ° C in which the method according to the invention is implemented.

Another object of the invention is to create a device allowing continuous production of cold.

According to the invention, this device comprises two reactors containing the same solid compound, communication circuits between these reactors, one evaporator, the condenser and the gas collector, and in that means are provided for successively triggering the solid reactions. - gas in the two reactors and to control the openings and closings of the various communication circuits in a predetermined order to obtain a continuous production of cold.

According to a preferred version of the invention, the aforementioned means are adapted to allow the following successive operating steps:

A) opening of the circuit between one of the reactors and the evaporator and between the latter and the gas collector,

B) opening of the circuit between the evaporator and the first reactor as soon as the gas pressure in the evaporator is higher than that in the first reactor,

C) opening of the circuit between the other reactor and

1 evaporator and between the latter and the gas collector,

D) opening of the circuit between the evaporator and the second reactor as soon as the gas pressure in the evaporator is higher than that in the second reactor,

E) opening of the circuit between the first reactor and the external heat source to heat the solid contained in this reactor,

F) opening of the circuit between the first reactor and the condenser as soon as the pressure in the reactor is higher than that in the condenser,

G) closing the circuit between the first reactor and the heat source and opening the circuit between the second reactor and the heat source,

H) closing under the effect of the pressure prevailing in the second reactor of the circuit comprised between the latter and the evaporator and opening of the circuit between the second reactor and the condenser,

I) closure, after pressure drop in the first reactor of the circuit between it and the condenser and opening of the circuit between this reactor and one evaporator.

According to an advantageous version of the invention, the device comprises a third reactor containing said solid compound capable of reacting with the gas and connected with the external heat source, the condenser, the collector and the evaporator, means being provided for triggering successively the solid-gas reactions in the three reactors in such a way that the third reactor can store energy without any energy input other than that necessary for the circulation of the heat transfer fluid.

Other features and advantages of the invention will appear in the description below.

In the appended drawings given by way of nonlimiting examples:

FIG. 3 is the diagram of a device for producing cold with a single reactor,

FIG. 4 is a diagram similar to FIG. 3 showing the first step in the operation of the device according to FIG. 3,

FIG. 5 shows the second step in the operation of the device according to FIG. 3,

FIG. 6 shows the third step in the operation of the device according to FIG. 3, FIG. 7 is the diagram of a device for producing cold with two reactors,

FIG. 8 shows the first step in the operation of the device according to FIG. 7,

FIG. 9 shows the second step in the operation of the device according to FIG. 7,

FIG. 10 shows the third step in the operation of the device according to FIG. 7,

FIG. 11 shows the fourth step of the device according to FIG. 7, FIG. 12 is the diagram of a device for producing cold with three reactors,

FIG. 13 shows the first step in the operation of the device according to FIG. 12, FIG. 14 shows the second step in the operation of the device according to FIG. 12,

- Figure 15 shows the third step in the operation of the device according to Figure 12, - Figure 16 shows the fourth step in the operation of the device according to Figure 12.

In the embodiment of FIG. 3, there is shown a device for producing discontinuous cold from the physicochemical phenomenon reacting manganese chloride and ammonia, as indicated below:

<Mn Cl ₂ , 2NH ₃ > + 4 (NH ₃ ) ^• = _ ^** - <MnCl ₂ , 6NH ₃ >

This device comprises: - a reactor R containing the solid reaction medium <MnCl ₂ , 2NH ₃ > which is connected to a condenser C, a collector Co of liquefied gas G included between the latter and an evaporator E.

This device also comprises a non-return valve Cl on the circuit connecting the reactor R to the condenser C, a non-return valve C2 on the circuit connecting the evaporator E to the reactor R, a thermostatic expansion valve DT on the connecting circuit the reactor R at the evaporator Ξ, a pressure-controlled valve VPC, an electrovalve EV1 isolating the reactor R from the rest of the circuit, an electrovalve EV2 isolating the evaporator E from the reactor R, two electrovalves EV3 and EV4 for defrosting and a EV5 solenoid valve for distributing a heat transfer fluid F in the EC exchanger contained in reactor E and connected to an external heat source S by means of a pump P.

The different stages of operation of the device are illustrated in FIGS. 4 to 6 and in the table below:

Table 1

* 0 = open; F = closed Initial state: step 0

The reactor R has a maximum cold potential, that is to say that the solid inside is composed of salt <S> capable of reacting with the gas (G).

All the solenoid valves are closed and the collector Co is filled with refrigerant [G]. For start-up, the EV1 solenoid valve is opened.

Step 1 (Figure 4)

The EV2 solenoid valve opens, the fluid G circulates from the collector Co to the evaporator E. In the latter, it vaporizes, the heat being given up by the fluid F2, for example air which is used to transport the production cold. The fluid F2 diffuses the frigories in the enclosure to be cooled. In the example shown, the air is blown into this enclosure by means of a fan Vi.

The thermostatic expansion valve (VPC) controls the pressure in the evaporator E and therefore the temperature of the boiling liquid G in the evaporator E. The pressure in the evaporator E being higher than the pressure in the reactor R, the valve C2 opens and the gas (G) will react with the solid <S> in the reactor R, the heat of reaction being removed via an exchanger or circulates F3. The fluid F3 is air drawn by a motor fan V3 which dissipates the exothermic heat of reaction towards the outside. Step 2 (Figure 5)

The synthesis reaction being completed in the reactor R, the valve EV5 opens, the solid <S, G> present in the reactor R, is heated by the fluid F4 which is for example a thermal oil. When the pressure in the reactor R is higher than that prevailing in the condenser C, or in the collector Co, the valve Cl opens, the valve C2 being closed as soon as the pressure in the reactor R was higher than that prevailing in 1 ' evaporator E. The gas coming from reactor R will condense at condenser C, then flow into the collector Co, the heat of condensation being evacuated by the fluid FI, the fluid FI being air as in a traditional installation at compression, blown by means of a V2 fan.

During this step 2 no production of cold is ensured, the fluid [G] being unable to circulate in the evaporator. The production of cold is therefore discontinued.

Step 3 (Figure 6)

This step, when it occurs in the cycle, corresponds to defrosting. This is done within the evaporator E itself by using it as a condenser.

The initiation of the defrosting operation must occur at step 2, that is to say during the operation of decomposition of the solid in the reactor R.

For this operation, the EV2 valve simultaneously closes and the EV3 valve opens. The gas (G) from the decomposition reaction in the reactor R will condense preferentially in one evaporator E and thus ensure defrosting. With the EV4 valve open, the condensed fluid [G] flows into the manifold Co.

Step 4

In this step, we return to step 1, that is to say the production of cold by one evaporator E.

The device that has just been described, although producing cold intermittently, makes it possible to produce cold down to -40 ° C. in the enclosure to be refrigerated, provided that the maximum temperature outside of it. this is at most equal to 30 ° C.

To this end, it is necessary: 1) to carry out the following simultaneous reactions inside the reactor R:

<X, mNH ₃ > + n (NH ₃ ) = » ^* • <X, (m + n) NHs> n [NH ₃ ] s_- n (NH ₃ ) then <X, (m + n) NH ₃ >_><X, mNH ₃ > + n (NH ₃ ) n (NH ₃ )> n [NHs]

X being chosen from ZnCl ₂ , CuSÛ, CuCl, LiBr, LiCl, ZnSÛ4, SrCl ₂ , MnCl ₂ , FeCl ₂ , MgCl ₂ , CaCl ₂ and NiCl ₂ , m and n being numbers such as:

m≈O, n≈l if X = LiCl, SrCl ₂ m≈l, n≈l. if X = LiCl, CaCl ₂ m = 2, n = 2 if X = ZnCl ₂ , CuS0 ₄ m≈l, n = 0.5 if X = CuCl m = 2, n≈l if X = LiBr, ZnS0 ₄ m = 2, n = 4 if X = nCl ₂ , FeCl ₂ , NiCl ₂ m = 4, n = 2 if X = MgCl ₂

2) that the external heat source S is at a temperature Th greater than a value such that ^* :

if X = ZnCl ₂ (m = 2, n = 2) Th = 139 ° C if X = CuS04 (m = 4, n≈l) Th = 145 ° C if X = CuCl (m≈l, n = 0, 5) Th = .151 ° C if X = LiBr (m = 2, n≈l) Th = 155 ° C if X = LiCK ≈l, n≈l) Th = 167 ° C if X = ZnS0 ₄ (m = 3, n≈l) Th = 173 ° C if X = SrCl ₂ (m≈O, n≈l) Th = 173 ° C if X = MnCl ₂ (m = 2, n = 4) Th = 174 ° C if X = LiCl (m≈O, n≈l) Th = 203 ° C if X = FeCl ₂ (m = 2, n = 4) Th = 208 ° C if X = MgCl ₂ (m = 4, n = 2) Th = 217 ° C if X = CuS0 ₄ (m = 2, n = 2) Th = 230 ° C if X = ZnS0 ₄ (m = 2, n≈l) Th = 247 ° C if X = CaCl ₂ (m ≈l, n≈l) Th = 265 ° C if X = NiCl ₂ (m = 2, n = 4) Th = 282 ° C

If you want to produce cold up to +10 ° C in the room to be refrigerated, the maximum temperature outside of this being at most equal to + 80 ° C., using the same solid-gas reactions, the temperature Th of the source S must be greater than a value such that:

if X = ZnCl ₂ (m = 2, n = 2) Th = 162 ° C if X ≈ CuSÛ4 (m = 4, n≈l) Th = 170 ° C if X = CuCl (m≈l, n≈0, 5) T Thh ≈ 180 ° C if X = LiBr (m = 2, n≈l) Th = 196 ° C if X = ZnS0 ₄ (m = 3, n≈l) Th = 200 ° C if X = LiCl ( m≈l, n≈l) Th = 208 ° C if X = MnCl ₂ (m = 2, n = 4) Th = 212 ° C if X = SrCl ₂ (m≈O, n≈l) Th = 217 ° C if X = LiCl (m≈O, n≈l) Th = 249 ° C if X = FeCl ₂ (m = 2, n = 4) Th = 256 ° C if X = MgCl ₂ (m = 4, n≈ 2) Th = 256 ° C if X = CuS0 ₄ (m = 2, n = 2) Th = 265 ° C if X = ZnS0 ₄ (m = 2, n≈l) Th = 282 ° C if X = CaCl ₂ (m≈l, n≈l) Th = 311 ° C if X = NiCl ₂ (m = 2, n = 4) Th = 338 ° C

It is therefore possible, using the same reaction chosen from the above reactions and using a heat source S whose temperature is at the appropriate value, produce cold at a temperature between + 10 ° C and - 40 ° C.

The cold production devices which will now be described also make it possible to produce cold. continuously, which makes them particularly suitable for industrial needs, especially in transport vehicles.

The device shown in FIG. 7 mainly comprises:

- two identical reactors (RI and R2) containing the solid reaction medium,

- a condenser C,

- a collector Co of liquefied gas G, - an evaporator E,

- two non-return valves (C1 and C2) on the circuits connecting the reactors RI and R2 to the condenser C,

- two non-return valves (C3 and C4) on the circuits connecting the evaporator E to the reactors RI and R2, - a thermostatic expansion valve (DT) between

The evaporator E and the collector Co,

- a pressure-controlled valve (VPC) between the reactors RI, R2 and the evaporator E,

- two electrσvalves (EV1 and EV2) isolating the reactors RI and R2 from the rest of the circuit,

- a solenoid valve (EV5) isolating the evaporator E from the reactors RI and R2,

- two solenoid valves (EV6 and EV7) for defrosting, - two solenoid valves (EV3 and EV4) for distributing a fluid F4 in the exchangers EC1 and EC2 contained in the reactors RI and R2.

The different stages of operation of this device are illustrated by Figures 8 to 11 and by Table 2 below.

Table 2

* if defrosting occurs during step 3

Initial state: Stage 0

The RI and R2 reactors have a maximum potential of cold, that is to say that the solids inside are composed of salt <S> capable of reacting with the gas (G). All the solenoid valves are closed and the Co manifold is filled with refrigerant.

Step 1: (Figure 8)

The EVl and EV5 solenoid valves open. The fluid G circulates from the collector Co to the evaporator E. In the latter it vaporizes, the heat being given up by the fluid F2 which is therefore used to produce cold.

The fluid F2 being air, it diffuses the frigories in the enclosure to be cooled.

The thermostatic expansion valve (DT) prevents the fluid G from circulating in the liquid state, beyond the evaporator E. The valve VPC controls the level of evaporation pressure and therefore the evaporation temperature. The pressure in the evaporator E being greater than the pressure in the reactor RI, the valve C3 opens and the gas (G) will react with the solid <S> in RI, the heat of reaction being removed by the through an exchanger where F3 flows. The fluid F3 is air drawn by a fan V3 which dissipates the exothermic reaction heat to the outside.

Step 2: (Figure 9) The synthesis reaction being completed in the reactor RI, the valve EV2 opens. The pressure at the evaporator E being higher than the pressure prevailing in the reactor R2, the valve C4 opens and the fluid G evaporates in one evaporator E and will react with the solid <S> present in the reactor R2.

The heat of evaporation is supplied to the evaporator E by the fluid F2 and the heat of reaction released in R2 is evacuated by the fluid F3.

Simultaneously with the opening of the EV2 valve, the EV3 valve opens. The solid <S, G> present in the reactor RI is heated by the fluid F4. When the pressure in the reactor RI is higher than that prevailing in the condenser C (or in the collector Co), the valve Cl opens, the valve C3 being ^" closed as soon as the pressure in R was higher than that prevailing at 1 'evaporator E.

The gas (G) from the reactors RI will condense in the condenser Co, the heat of condensation being evacuated by the fluid Fl, and flows into the collector Co.

Step 3: (Figure 10)

When the reactions in the reactors Ri and R2 are finished, the valve EV3 closes and the valve EV4 opens. The solid <S, G> present in R2 is heated by the fluid F4. The pressure in R2 rises and successively the valve C4 closes and the valve C2 opens. The gas (G) from R2 will condense at E, the heat of condensation etan evacuated by the fluid F1, and flows in the collector Co. The fluid F3 circulates in the exchanger E of the reactor.

RI. As it cools, the pressure drops and successively the valve Cl closes and the valve C3 opens. The fluid (G) evaporates at E and will react in the reactor RI with the solid <S>. As before, the heat of evaporation is provided by the fluid F2 (air) which cools and is therefore used for the distribution of cold, in the enclosure to be cooled.

Step 4: (Figure 11)

This step, which can occur during step 2 or 3, concerns the defrosting operation. This is done within one evaporator E itself, using it as a condenser.

When the defrost starts, the EV5 valve closes and the EV6 valve opens.

The gas (G) resulting from the decomposition reaction will condense preferentially in one evaporator E. The heat of condensation released ensures the defrosting. With the EV7 valve open, the condensed fluid G flows into the manifold Co.

Step 5: This step corresponds to returning to the normal cycle after the defrosting operation. The EV6 and EV7 valves close and EV5 opens.

The gas (G) goes from the reactor RI heated by the fluid F4 to the condenser C and the collector Co. The gas G evaporates at E and will react with the solid

<S> in the reactor cooled by fluid F3. As described in step 2 or 3, the cycle resumes normally by alternating steps 2 or 3. Step 6:

This step does not correspond to the normal operating cycle but it allows the machine to restore its full refrigeration potential (step 0).

During this stage, there is no production of cold and the two reactors RI and R2 are brought back to their maximum cold potential.

The ΞV3 and EV4 valves are open. The solid <S, G> present in the reactors RI and R is heated by the fluid F4.

The gas (G) produced during the decomposition of <S, G> condenses in C and flows into the collector Co. The operation is terminated when there is only solid <S> in each RI and R2 reactors. The valves EV1 to EV5 are then closed, the valves Cl, C2 closing as a result of pressure drop in RI and R2, this being consecutive to the stopping of the heating of the reactors.

The above device, when it implements the solid-gas reactions described above allows not only a continuous production of cold, but also to obtain temperatures between - 40 ° C and + 10 ° C optimal for transport food or other products at low temperatures. FIG. 12 represents a cold production device making it possible, from a discontinuous physicochemical phenomenon, to ensure a continuous production of cold and a storage of refrigerating energy. This device mainly comprises:

- three identical reactors (RI, R2, R3) containing the solid reaction medium,

- a condenser C, - a collector Co of liquefied gas G,

- an evaporator E,

- three non-return valves (Cl, C2, C3) on the circuit connecting the reactors RI, R2, R3 to the condenser C,

- three non-return valves (C4, C5, C6) connecting the evaporator E to the reactors RI, R2, R3,

- a thermostatic expansion valve (DT) between the evaporator E and the collector Co,

- three solenoid valves (EV1, EV2, EV3) isolating the reactors RI, R2 and R3 from the rest of the circuit, - three solenoid valves (EV4, EV5, EV6) allowing to distribute a fluid F4 in exchangers (ECl, EC2, EC3) contained in reactors RI, R2, R3.

The different stages of operation of this device are shown in Figures 13 to 16 and in Table 3 below.

Table 3

Step 0: initial state

The reactors RI, R2 and R3 have a maximum cold potential, that is to say that the solids inside consist of the salt <S> capable of reacting with the gas (G). All solenoid valves are closed and the manifold Co is filled with refrigerant / G /.

Step 1: start-up (figure 13)

The EV1 solenoid valve opens. G the fluid flows from the manifold to the Co ^r evaporator E. In the latter, it s vaporizes, the heat being transferred by the fluid F2 which is used to distribute the cold. The thermostatic expansion valve (DT) prevents the fluid £ QJ from flowing, in the liquid state, beyond the evaporator E. The pressure in the evaporator is higher than the pressure in RI, the valve C4 opens and the gas G will react with the solid <S> in the reactor RI, the heat of reaction being removed via an exchanger where F3 circulates.

Step 2: cycle (phase 1) (Figure 14)

The synthesis reaction being completed in the reactor RI, the valve EV2 opens. The pressure at one evaporator E being greater than the pressure prevailing in the reactor R2, the valve C5 opens and the fluid fθJ, which evaporates at E, will react with the solid <S> present in the reactor R2.

The heat of evaporation is supplied to the evaporator E by the fluid F2 and the heat of reaction released in R2 is evacuated by the fluid F3. Simultaneously with the opening of the valve EV2 occurs the opening of the valve EV4: the solid <S, G> present in the reactor RI is heated by the fluid F4. When the pressure in RI is higher than that prevailing in the condenser (or at the manifold), the valve Cl opens, the valve C4 having closed as soon as the pressure in RI was higher than that prevailing in the evaporator E. The gas (G) from RI will condense in the condenser C by the fluid Fl, and flows into the collector Co.

Step 3: cycle (phase 2) (figure 15) When the reactions in the reactors RI and R2 are finished, the valve EV4 closes and the valve EV5 opens. The solid <S, G> present in R2 is heated by the fluid F4. The pressure in R2 increases and, successively, the valve C5 closes and the valve C2 opens. The gas (G) from R2 will condense in the condenser C, the heat of condensation being evacuated by the fluid Fl, and flows in the collector Co. The fluid F3 circulates in the exchanger in the evaporator E of the RI reactor. As it cools, the pressure drops and successively, the valve Cl closes and the valve C4 opens. The fluid (G) evaporated in one evaporator E will react in the reactor RI with the solid <S>. The heat of evaporation is, as before, provided by the fluid F2 which cools and is therefore used for the production of cold.

The alternation of phases 1 and 2 constitutes the normal operating cycle of the system.

Step 4: Operation on storage (figure 16) The fluid F4 is not heated and no longer circulates in the reactor R2. The circulation of (G), of R2 towards the condenser C, is interrupted by the closing of the valve

EV2.

The fluid F3 no longer circulates in the reactor RI, the circulation of (G) from the evaporator to the reactor RI is interrupted by the closing of the valve EV1.

The EV3 solenoid valve is open and the fluid F3 circulates in an exchanger EC3 located in the reactor R3. The pressure in one evaporator E being higher than the pressure prevailing in R3, the valve C6 opens and the fluid (G) evaporated in E goes. react with the solid * S> in R3; the heat of reaction is removed by F3 and the cold is conveyed by the fluid F2 cooled in one evaporator E.

Step 5: resumption of the cycle (phase 2) When the storage operation is stopped, the normal cycle resumes in step 3 (cycle: phase 2). The EV3 valve is closed and the EV1 and EV2 valves are reopened. The fluid F4 is heated and circulates again in the reactor R2. The operation is then identical to that described in step 3.

Step 6: recharge

This step corresponds to stopping the cycle and returning the entire system to the initial state.

The EV1, EV2 and EV3 valves are open. The EV4, EV5 and EV6 valves being open, the F4 fluid circulates RI within three _reactors. R2 and R3. The solids inside these are heated: when the pressure in RI, R2 and R3 is higher than the pressure prevailing at the condenser, the valves Cl, C2 and C3 open and the gas (G), coming from decompositions of <S, G> will condense in the condenser and flow to the collector _Co, The heat of condensation is evacuated by the fluid Fl. =

This operation is carried out until the reactors - e contain more than - solid - <5>, that is to say until one is brought back to step 0 Initial state).

As described with reference to two ^"reactor device, the techniques used for temperature control (VPC) and for defrosting peuvent- be - applied to this device three-reactors.

It emerges from the description._p_εéçitée_ that the third reactor R3 makes it possible to store energy without supplying energy other than that necessary for the circulation of the coolant F4.

Of course, the invention is not limited to the exemplary embodiments which have just been described and many modifications can be made to them without going beyond the ambit of the invention.

Thus, the heat source S used to heat the reactors R, RI, R2, R3 can be any heat source of thermal or electrical origin available, provided that it is at the required temperature Th.

Fluid F4 can be any other fluid coolant than oil.

Furthermore, the fluids F1, F2, F3 can be other than air.

Of course, the method and the device according to the invention can also be applied to the air conditioning of buildings, in particular living quarters.

Claims

CLAIMS 1. Process for producing cold by means of a device comprising a reactor (R, RI, R2, R3) which contains a solid compound capable of reacting with a gas according to an exothermic reaction, this reactor being connected to a condenser ( C), a gas collector (Co) and an evaporator (E) which is in heat exchange relation with an enclosure to be cooled, the interior of the reactor being in heat exchange relation with a heat source (S) external, characterized in that the following simultaneous reactions are carried out in the reactor (R, RI, R2, R3):

<X, mNH ₃ > = n (NH ₃ ) - ^* = ^* * <X, (m + n) NH ₃ n [NH ₃ ] ^ n (NHs) then <X (m + n) NH ₃ = »< X, mNH ₃ > + n (NH ₃ ) n (NHs) • __ "• n [NHs]

the symbols <>; []; () respectively designating the solid, liquid and gaseous states,

X being chosen from ZnCl ₂ , CuS0 ₄ , CuCl, LiBr, LiCl, ZnS0 ₄ , SrCl ₂ , nCl2, FeCl ₂ , MgCl ₂ , CaCl ₂ and NiCl ₂ , m and n being numbers such as: m = 3, n≈l if X = ZnS0 ₄ m = 4, n≈l if X ≈ CuS0 ₄ m≈O, n≈l if X = LiCl, SrCl ₂ m≈l, n ≈l if X = LiCl, CaCi ₂ m≈2, n = 2 if X = ZnCl ₂ , CuS0 ₄ m≈l, n = 0.5 if X = CuCl m = 2, n≈l if X = LiBr, ZnS0 ₄ m = 2, n = 4 if X = MnCl ₂ , FeCl ₂ , NiCl ₂ m = 4, n = 2 if X = MgCl ₂

2. Method according to claim 1, characterized in that in order to produce cold down to -40 ° C in the enclosure to be refrigerated, the maximum temperature outside thereof being at most equal to 30 ° C, an external heat source (S) is used whose temperature is higher than a Th value such that:

if X ≈ ZnCla (m = 2, n = 2) Th = 139 ° C if X = CuS0 ₄ (m = 4, n≈l) Th = 145 ° C if X = CuCl (m≈l, n = 0, 5) Th = 151 ° C if X = LiBr (m = 2, n≈l) Th = 155 ° C if X = LiCl (m≈l, n≈l) Th = 167 ° C if X = ZnSO-j ( m = 3, n≈l) Th = 173 ° C if X = SrCl ₂ (m≈O, n≈l) Th = 173 ° C if X = MnCl ₂ (m = 2, n = 4) Th = 174 ° C if X = LiCl (m≈O, n≈l) Th = 203 ° C if X = FeCl ₂ (m = 2, n = 4) Th = 208 ° C if X = MgCl ₂ (m = 4, n = 2) Th = 217 ° C if X = CuS0 ₄ (m = 2, n = 2) Th = 230 ° C if X = ZnS0 ₄ (m = 2, n≈l) Th = 247 ° C if X = CaCl ₂ (m≈l, n≈l) Th = 265 ° C if X = NiCl ₂ (m = 2, n = 4) Th = 282 ° C

3. Method according to claim 1, characterized in that in order to produce cold up to + 10 ° C in the enclosure to be refrigerated, the maximum temperature outside thereof being at most equal to ⁾ + 80 ° C, an external heat source (S) is used whose temperature is higher than a Th value such that:

if X ZnCl2 (m = 2,, n = 2) Th = 162 ° C if X GuSO-i (m = 4, -n≈l) Th = 170 ° C 0 if X CuCl (m≈l, n = 0 , 5) Th = 180 ° C if X LiBr (m = 2, n≈l) Th = 196 ° C if X ZnS0 ₄ (m = 3, n≈l) Th = 200 ° C if X LiCl (m≈l , n≈l) Th = 208 ° C if X MnCl ₂ (m = 2, n = 4) Th = 212 ° C 5 if X SrCl ₂ (m≈C ', n≈l) Th = 217 ° C if X LiCl (m≈O, n≈l) Th = 249 ° C if X FeCl ₂ (m = 2, n = 4) Th = 256 ° C if X MgCl ₂ (m = 4, n = 2) Th = 256 ° C if X CuSθ4 (m = 2, n = 2) Th = 265 ° C 0 if X ZnS0 ₄ (m = 2, n≈l) Th = 282 ° C if X CaCl ₂ (m≈l, n≈l) Th = 311 ° C if X NiCl ₂ (m = 2, n = 4) Th = 338 ° C

4. Device for producing cold at a temperature between -40 ° C and + 10 ° C in which the process according to one of claims 1 to 3 is carried out.

5. Device according to claim 4, characterized in that the device comprises two reactors (RI, R2) containing the same solid compound, communication circuits between these reactors, the evaporator (E), the condenser (C) and the gas collector (Co), and in that means are provided for successively initiating the solid-gas reactions in the two reactors and for controlling the openings and closings of various communication circuits in a predetermined order to obtain a continuous production of cold ^*.

6. Device according to claim 5, characterized in that it comprises means for controlling the following successive steps:

A) opening of the circuit between one (RI) of the reactors and one evaporator (E) and between the latter and the gas collector (Co),

B) opening of the circuit between the evaporator (E) and the reactor (RI) as soon as the gas pressure in the evaporator (E) is higher than that in the reactor (RI),

C) opening of the circuit between the other reactor (R2) and the evaporator (E) and between the latter and the gas collector (Co),

D) opening of the circuit between the evaporator (E) and the reactor (R2) as soon as the gas pressure in The evaporator (E) is greater than that in the reactor (R2),

E) opening of the circuit between the reactor (RI) and the source (S) of external heat to heat the solid contained in this reactor,

F) opening of the circuit between the reactor (RI) and the condenser (C) as soon as the pressure in the reactor is higher than that in the condenser,

G) closing of the circuit between the reactor (RI) and the heat source (S) and opening of the circuit between the reactor (R2) and the heat source (S),

H) closing under the effect of the pressure prevailing in the reactor (R2) of the circuit comprised between the latter and the evaporator (E) and opening of the circuit between the reactor (R2) and the condenser (C),

I) closing, after pressure drop in the reactor (RI) of the circuit between the latter and the condenser (C) and opening of the circuit between this reactor (RI) and one evaporator (E).

7. Device according to claim 6, characterized in that it comprises means for triggering the defrosting, these means being adapted to control the following operations: closing of the circuit between the two reactors (RI) and (R2), opening of the circuit between the evaporator (E) and the condenser (C) and opening of the circuit between the evaporator (E) and the gas manifold (Co).

8. Device according to claim 7, characterized in that it comprises means for controlling, after defrosting, the following operations: closing of the circuits between the evaporator (E) and the condenser (C) and between 1 evaporator (E) and the gas collector (Co).

9. Device according to one of claims 5 to 8, characterized in that said means comprise electromagnetic control valves and check valves.

10. Device according to one of claims

5 to 9, characterized in that said means comprise a pressure-controlled valve (VPC) on the circuit connecting the two reactors (RI, R2) to the evaporator (E) to control the pressure and the temperature of evaporation of the gas .

11. Device according to one of claims

5 to 10, characterized in that said means comprise a thermostatic expansion valve (DT) on the circuit connecting one evaporator (E) to the manifold (Co) to prevent the fluid condensed in the condenser (C) to circulate in the liquid state beyond 1 evaporator (E).

12. Device according to one of claims 5 to 10, characterized in that it comprises a third reactor (R3) containing said solid compound capable of reacting with the gas and connected with the source (S) of external heat, the condenser (C), the collector (Co) and the evaporator (E), means being provided for successively triggering the solid-gas reactions in the three reactors (RI, R2, R3, R4) in such a way that the third reactor (R3) can store energy without providing any energy other than that necessary for the circulation of the heat transfer fluid (F4).

13. Device according to claim 12, characterized in that said means are adapted to allow the following successive operating steps:

A) opening of the circuit between the first reactor (RI) and the evaporator (E) and between the latter and the collector (Co),

B) opening of the circuit between this reactor (RI) and the condenser (C), between the second reactor (R2) and the evaporator (E) and between the collector (Co) and the condenser (C),

C) opening of the circuit between the first reactor (RI) and the evaporator (E), between the second reactor (R2) and the condenser (C) and between the latter and the collector (Co),

D) opening of the circuit between the third reactor (R3) and the evaporator (E) and between the latter and the collector (Co).

14. Device according to one of claims 5 to 13, characterized in that the heat transfer fluid (F4) flowing between the reactors and the external heat source is oil.

15. Device according to one of claims 5 to 14, characterized in that the means for removing the heat given off during the solid-gas reaction and for removing the heat of condensation comprise means for heat exchange with the air ambient.