Patent Grant
10508837
This application is a National Stage of International Application No. PCT/FR2015/052600 filed Sep. 29, 2015, claiming priority based on French Patent Application No. 1459333 filed Oct. 1, 2014, the contents of all of which are incorporated herein by reference in their entirety.
Field of the Invention
The present invention concerns a method of bringing to temperature and holding at temperature the interior of a thermally insulated enclosure with no continuous supply of energy, and a device for bringing to temperature and holding at temperature the interior of a thermally insulated enclosure capable of implementing the aforementioned method.
Description of Related Art
Certain compounds in the gaseous state can be reversibly absorbed by another compound in the liquid state. This is true of water in vapor form which can be absorbed by a solution of lithium bromide. There are also solids that are capable of reacting with gases during a reversible exothermic reaction to produce a solid product. This is the case, for example, for alkaline or alkaline-earth metal chlorides that react particularly with ammonia. There are also solid compounds such as zeolites on which a gas can be absorbed reversibly. The aforementioned absorption, adsorption and chemical reaction are exothermic and reversible; they are currently used for the production of cold and heat.
The document WO 2006/100412 A1 describes a device that comprises a thermally insulated enclosure, means of placing in circulation the air contained in the enclosure and a thermochemical system. Said thermochemical system comprises a gas reservoir capable of being placed in communication, through valve means, with a reactor; said reactor contains a solid reagent capable of reacting with the gas contained in the reservoir in order to form, during a reversible exothermic chemical reaction, a solid product. When the valve means are opened, the pressure of the gas in the reservoir decreases continuously because the gas is consumed in the reactor: the drop in pressure in the reservoir causes an absorption of heat from the ambient environment. At the same time, the chemical reaction that takes place in the reactor produces heat. The device described in the aforementioned document, thanks to the means of placing the air in circulation, makes it possible either to heat the air contained in the enclosure in contact with the reactor, or to cool it in contact with the reservoir. Said device therefore makes it possible either to heat or cool the thermally insulated enclosure, without external supply of energy, once the chemical reaction has begun. When all of the gas has reacted with the reagent, the reactor must then be reheated to induce the reverse endothermic reaction and refill the reservoir with gas. During this so-called regeneration phase, the device can no longer be used. The autonomy of the device is therefore directly related to the quantity of reagents, and particularly of the gas contained in the reservoir.
If it is desired to increase the autonomy of the aforementioned device, one solution consists of increasing the quantity of gaseous reagent. The device then becomes very cumbersome and heavy. Moreover, because the reactor is also of a large size, its regeneration phase becomes longer.
Furthermore, the document WO 2013/164539 A1 describes a device comprising two thermochemical systems that function alternately. When one of the thermochemical systems is in the regeneration phase by means of the electrical resistances that surround the reactor, the other is in the cold production phase. Means of determining the progress of the reaction make it possible to optimize the alternating of the regeneration phases. This device is not autonomous because its operation requires that one of the reactors be in the regeneration phase, which means that the device during its operation is always connected to a source of electricity. The only means of making the device mobile and autonomous is to associate a source of electricity with it that is capable of continuously supplying the electricity during its operation. Such a device proves to be expensive and cumbersome.
One purpose of the present invention is to propose a device for bringing to temperature and holding at temperature the interior of a thermally insulated enclosure that has improved autonomy compared to the device described in the document WO02006/100412 A1.
Another purpose of the present invention is to propose a device which, for the same quantity of fluid, has increased autonomy compared to the device described in the document WO2006/100412 A1.
Another purpose of the present invention is to propose a device that is capable both of producing cold and/or heat continuously and of functioning autonomously.
Another purpose of the present invention is to propose a method of producing cold and/or heat that can be implemented particularly by using the device according to the invention and which makes it possible to increase the time of utilization of said device in autonomous operation, particularly for the production of cold.
The present invention proposes a device enabling the bringing to temperature and holding at temperature of a thermally insulated enclosure, which device is capable of functioning autonomously during a given period of time. According to the invention, characteristically the device comprises: at least a first and a second system chosen independently of each other from among absorption systems, adsorption systems and thermochemical systems, said first and second systems each comprising:
Also, characteristically said heating means comprise means of temporary connection to an energy source external to said device, said temporary connection means being capable of being connected or disconnected from said external energy source; said device further comprises,
The presence of the second system makes it possible to consider the regeneration of the reactor of the first system during which the second system operates to produce the cold or heat. The regeneration of one of the systems potentially increases the duration of overall autonomy of the device of the invention; indeed, it is therefore possible to benefit from the presence of an external source of energy to produce the even partial regeneration of the reactors. When the device is then disconnected from said external energy source, it can again operate autonomously without the temperature in the enclosure being modified.
The presence of two systems makes it possible to increase the quantity of fluid able to react, while limiting the size of the device; the two systems can be of average size and judiciously disposed in the device.
The thermally insulated enclosure is not limited according to the invention; it can involve a thermally insulated enclosure having, for example, an overall coefficient of thermal transfer greater than or less than or substantially equal to 0.4 W/m2/° C.
According to the invention, the means of determining the quantity of fluid not having reacted that is present in each of the systems are not limited; they can involve means of measuring the quantity of fluid in liquid form in the reservoir of the system, or means of measuring the pressure of the gaseous fluid in the system concerned. They can also involve means of measuring the temperature in the evaporator, or means of measuring the temperature in the condenser which indirectly provide a status of the progress of the reaction taking place in the reactor. Any means making it possible to determine directly or indirectly the quantity of fluid not having reacted can be used within the scope of the present invention.
The means of control ensure operation of the device without intervention of the user.
The means of temporary connection to an external energy source can include, for example, at least one electrical plug or any other means, when the device is supplied by an energy source, particularly electric, to enable said supply to be cut off without cutting the physical connection between the source and the device. This can involve a switch, for example. Advantageously, the means of temporary connection comprise an electrical plug, the external energy source being the electric mains.
Advantageously, said reservoir contains the fluid in liquid/vapor phase equilibrium and said device further comprises at least one evaporator connected to the outlet of the at least one of said reservoirs. It is therefore possible to produce more frigories.
Advantageously, the device comprises at least one condenser mounted between said reactor and said reservoir of at least one of said systems. The device can therefore comprise two evaporators and two condensers, one evaporator and one condenser for each of the systems.
According to one embodiment, said reservoir of each of said systems and/or said evaporator and/or said condenser is/are disposed in such a way as to enable a heat transfer with the internal volume of said thermally insulated enclosure.
The enclosure can also contain two evaporators and/or at least one of the reservoirs.
Advantageously, said reservoir of each of said systems and/or said evaporator is disposed in said thermally insulated enclosure.
Advantageously, the device comprises means of cooling the reactors of said systems. Said cooling means can be fans for example, or any other means of cooling capable of functioning autonomously.
The device of the invention can form an integral part of a vehicle. Thus, the thermally insulated enclosure can make up an integral part of the trunk of a vehicle or be contained in the trunk of the vehicle. The temporary means of connection then comprise an electrical plug capable of being connected to the electric mains and/or to the battery of the vehicle.
According to another embodiment that can be combined with the preceding one, when the vehicle is at rest, the heating means are designed to use the electric energy from the battery of the vehicle to regenerate at least one of the reactors. In this case, the vehicle also has means for detecting the status of the charge of the vehicle's battery. It is possible, within the scope of the present invention, to use any available source of energy in the vehicle when underway or when stopped to regenerate the reactors. Thus, for example, the heat can be used from the exhaust gases, or the heat released during braking to regenerate the reactors.
The present invention also relates to a method of producing cold and/or heat in a thermally insulated enclosure, capable of being implemented in a device enabling the bringing to temperature and holding at temperature of a thermally insulated enclosure, said device comprising:
According to the method of the invention,
a) the reactor of one of said systems is heated until complete regeneration, while the other system maintains the temperature of the internal volume of said enclosure at said setpoint temperature;
b) when the reactor is completely regenerated, the system having the reactor that has just been regenerated is used to maintain the temperature of the internal volume of said enclosure at said setpoint temperature before all the reagent and/or all the fluid of the other system is consumed in said exothermic reaction, and the reactor of the other system, which still contains reagent and said fluid capable of reacting, is heated until its complete regeneration;
The Applicant has revealed that the implementation of steps a) and b) above make it possible to increase the autonomy of the aforementioned device, irrespective of the moment when the connection means are disconnected from the external energy source.
The disconnection of the connection means can be voluntary and implemented by the user, but can also involve an involuntary or accidental disconnection, such as a power failure.
This method can be used to cool and/or heat the interior of the thermally insulated enclosure. It can be implemented when the setpoint temperature is higher than the ambient temperature or when the setpoint temperature is lower than the ambient temperature.
Advantageously, the setpoint temperature is lower or higher than the ambient temperature throughout the implementation of the method of the invention.
The Applicant has revealed that the aforementioned method made it possible to increase the duration of autonomy of the device of the invention.
Indeed, the Applicant's distinction is having revealed that the regeneration of a reactor would produce a thermal transfer to the thermally insulated enclosure and that it was then necessary to increase the flow of fluid entering into the reactor of the system in operation in order to compensate for the aforementioned thermal transfer. The Applicant has also verified that the bringing the enclosure to temperature requires more energy than holding it at temperature, and that the energy expended (and thus the quantity of fluid that can react) to counteract the thermal transfer due to the reactor in the process of regeneration was minimal when the steps a) and b) above were implemented at least once. The repetition of the steps a) and b) enables the autonomy of the aforementioned device to be increased still more.
Advantageously, said valve means of each of the systems are kept closed for a given period of time after having caused said given quantity of fluid to penetrate into the at least one of said reactors. Said period of time during which the systems are at rest makes it possible to achieve thermal equilibrium in the thermally insulated enclosure of the device of the invention, and to economize on the fluid. Said period of time depends on the insulation of the thermal enclosure.
Advantageously, if the two systems are used to bring the internal volume of said enclosure to said setpoint temperature, the quantity is determined of fluid not having yet reacted in each of said systems, and the reactor is heated of the system that contains the smallest quantity of fluid not having reacted.
According to one implementation, the reactor is used in which the reagent has just been regenerated in order to maintain the temperature of the internal volume of the enclosure at said setpoint temperature before the temperature of said reactor reaches the temperature of the ambient environment at said enclosure. For example, the system can be used when the temperature of the reactor is substantially equal to 70° C.
Indeed, the Applicant has shown that the temperature of the reactor and therefore the pressure therein had no influence on the production of heat and/or cold in the enclosure. It is therefore also possible to shorten the period during which the system is not used (because of its regeneration and its excessive temperature caused by the regeneration) by quickly using the regenerated reactor, without waiting for it to reach ambient temperature. Because the period of nonuse of the system in regeneration is reduced still more, the consumption of fluid in the other system is therefore also reduced.
Advantageously, for each of the systems, the reservoir contains at least the quantity of fluid capable of reacting with all of the reagent contained in the reactor. Advantageously, it contains substantially the quantity of fluid necessary for consumption, during the exothermic reaction, of all the reagent contained in the reactor.
Definitions
Within the meaning of the present invention, an absorption system is a system that comprises a liquid in which a gas is absorbed, without change of volume.
Within the meaning of the present invention, an adsorption system is a system that comprises a solid at the surface of which the molecules of a gas can be attached without creating a covalent bond, but by simple interactions of the van der Waals type for example. A system comprising zeolites is an example of an adsorption system.
The term “thermochemical system” within the meaning of the present invention designates a system in which a fluid (gas or liquid) reacts with a reagent, advantageously solid, to form a new solid or liquid product, with creation of covalent bonds. The reagent can be in liquid, gas or solid form. One example of such a system is ammonia in the form of gas which reacts with manganese chloride, or barium chloride.
For reasons of simplicity throughout the present application, the term “react” will be used irrespective of whether it involves a thermochemical system or an adsorption or absorption system. Similarly, the term “reaction” is used both for a true chemical reaction as well as for an adsorption or an absorption.
The term “regeneration” and the affiliated terms such as “regenerated” designate, when applied to a reactor, the desorption of the adsorbed or absorbed product, depending on the situation, or the decomposition of the product obtained during the exothermic reaction between the reagent and the fluid. The decomposition of said reaction product makes it possible to obtain directly or not the fluid, which can then react again with the regenerated reagent. The term “regenerated reactor” indicates that the product of the exothermic reaction has been totally decomposed and that all the fluid and the reagent of the reactor are again usable.
The term “reverse reaction” designates either the desorption of the gas adsorbed on a solid, or the changeover of the absorbed gas into a liquid in gaseous form, or the thermal decomposition reaction of the product of the chemical reaction between the reagent and the gas. In every case, said reaction is endothermic.
The term “autonomy” means that the device produces cold and/or heat with no external supply of energy for a given period of time, in particular with no supply of energy to regenerate one of the reactors by heating. Autonomous operation means that the device according to the invention can be moved during its operation and that it does not need to be connected to an external energy source during its operation, particularly to a source of electricity.
Ambient temperature refers to the temperature of the environment outside the thermally insulated enclosure and the device in general.
The present invention, its characteristics and various advantages will be better understood from the following description of an embodiment of the device of the invention and of an example of implementation of the method of the invention, with reference to the appended figures in which:
With reference to
The systems TCU1 and TCU2 are thermally insulated from each other. However, the reactors 15 and 25 and/or the condensers 17 and 27 can be thermally connected with the interior of the enclosure 5. They can therefore potentially heat said enclosure when the setpoint temperature is higher than the ambient temperature.
As represented in
In the embodiment represented in
One mode of operation of the device of the invention will now be explained with reference to
At t=0, the internal temperature of the enclosure 5 is substantially equal to 25° C., which is the ambient temperature. The ambient temperature does not vary throughout the implementation of the method. The two reservoirs 1 and 2 are filled with liquid ammonia in equilibrium with ammonia gas. To cool the enclosure 5, the solenoid valve EV1 of the first system TCU1 is opened, thus causing the gas to enter from the reservoir 1 to the reactor 15. The gas is consumed during its exothermic reaction with the solid reagent contained in the reactor 15. The evaporation of the liquid in the evaporator 13 generates an absorption of heat inside the enclosure 5, thus cooling it. A certain quantity of fluid is consumed to bring the temperature of the enclosure 5 to the setpoint temperature Tc.
When the setpoint temperature Tc is reached, the plug P1 is connected to the mains to regenerate the reactor 15 of the system TCU1. This configuration is represented in
The second system TCU2, which still contains fluid and reagent capable of reacting, is then used to hold the temperature in the enclosure 5 at the setpoint value Tc. The solenoid valve EV2 is then opened. While the second system TCU2 cools the enclosure 5, the regeneration by heating the reactor 15 produces calories which should compensate for the cooling of the second system TCU2. The quantity of liquid ammonia present in the reservoir 1 is measured in the first system TCU1 as a function of time. When the level of liquid ammonia returns to the same value as at t=0, the heating of the reactor 15 is stopped, which is thus fully regenerated, and the reactor 25 is heated. The reactor 15 is therefore fully regenerated and is quickly used to maintain the enclosure 5 at the setpoint temperature.
The aforementioned steps are repeated as long as it is possible to connect the heating means 19 and 29 to the mains.
At t=t1, the heating means 19 and 29 are disconnected from the mains and the systems TCU1 and TCU2 are used to maintain the temperature of the enclosure 5 at the value Tc until all of the reagent of the reactor has reacted or all of the fluid has reacted, depending on how the quantity of fluid or reagent limits the exothermic reaction. A switchover is then made to the second system which is used to maintain temperature. As will be explained later, the aforementioned steps make it possible to optimize the quantity of fluid not having reacted in both of the systems TCU1 and TCU2.
Cooling of a Thermally Insulated Enclosure to a Setpoint Temperature
A device according to
At the end of regeneration, the reactors are cooled to return them to a lower temperature, which is either the ambient temperature or a temperature above ambient temperature but which allows the use of the system for producing heat and/or cold. The reactors are also cooled during their use for producing heat and/or cold, whether the device is functioning in autonomous mode or is connected to an external source of energy (the mains). The cooling of the reactors makes it possible to have a lower temperature on the evaporators. The fans can therefore be supplied with 12 V by the battery mounted in the device and capable of being supplied through a transformer connected to the mains.
The reversible exothermic chemical reaction taking place in the reactors is as follows:
(MnCl22.NH3)+4NH3←→MnCl2,6.NH3 (47 kJ/moleNH3)
The temperatures and pressures in the various elements of the system are measured while it is in operation to verify that they correspond properly to the values calculated with the Clapeyron diagram.
In the step during which the exothermic reaction takes place in the reactor, for a setpoint temperature equal to 2° C., an ambient temperature substantially constant and equal to 25° C., the maximum temperature in the reactor is 80° C., which is reached at the beginning of reaction and the minimum temperature is 60° C. at the end of reaction. During the exothermic reaction, the temperature in the reactor is substantially stable and equal to 70° C. When the reaction is ended, the temperature in the reactor decreases. The pressure in the system drops then remains constant when the setpoint temperature is reached, due to the adjustment of the flow of ammonia entering the reactor. All ammonia entering is consumed in the exothermic reaction. When the setpoint temperature is reached, the pressure P1 is 2.2 bar. An increase in pressure in the system indicates that the ammonia is no longer being consumed in the reactor and that the exothermic reaction is ended. The temperature in the evaporator is substantially equal to minus 20° C. when the valve means are opened. The temperature increases slightly to stabilize at minus 15° C. during the exothermic reaction, once the setpoint temperature is reached. The increase in temperature in the evaporator indicates the end of the exothermic reaction. The temperature and pressure values are given by the Clapeyron equation diagrams.
Operation with a Single System
If a single thermochemical system is used, a temperature of 2° C. in the enclosure can be reached in 30 minutes (the initial temperature in the enclosure being 25° C.). Said drop in temperature consumes 68.8% of the ammonia of the reservoir. The temperature can then be maintained at 2° C. for 23 hours, which corresponds to an autonomous operation of 23.5 hours.
Operation with Two Systems in Phase Opposition
The curve A represents the variations in pressure P in the first thermochemical system as a function of time. The curve B represents the variations in pressure in the second thermochemical system. The curve C represents the variations of the temperature in the thermally insulated enclosure 5, the setpoint temperature being equal to 2° C. The two reservoirs 1 and 2 are filled before beginning to cool the enclosure 5. Each of the regeneration phases lasts six hours, including the increase in temperature of the reactor concerned and the decrease of its temperature down to ambient temperature after regeneration and prior to its use for cooling the enclosure. At t=18.6 hrs, the heating means of the reactors are disconnected from the mains.
It can be seen in
The following Tables I and II show the results concerning the consumption and regeneration of gaseous ammonia in the systems of the device as a whole at the different times indicated in
It will be noted from the above results that with two systems in opposition cold can be produced continuously for as long as the heating means of the reactors are supplied with electricity. If the device is disconnected from said external source of energy, after the enclosure has been brought to temperature and after at least one regeneration of the first system used to bring it to temperature, the device contains at least 156.7% of gaseous ammonia still usable in autonomous mode, which corresponds to 50 hours of autonomous refrigeration.
Operation according to the Method of the Invention
In the following example, a quantity of ammonia is determined that is available for reacting in the reactor by measuring the pressure in the system concerned. It is known that when the pressure is maximal, the reactor is totally regenerated. The stopping of the regeneration phase of the reactor is triggered when the pressure in the system that includes the reactor concerned is substantially equal to Pmax. The regeneration phases last from 2.4 to 2.8 hours each depending on the quantity of reagent to be regenerated. The regeneration phases become shorter and shorter when the steps a and b are repeated.
Tables III and IV below assemble the results obtained from a model of operation of the aforementioned device with the mode of operation according to the invention. The numbers also indicate the percentage of gaseous ammonia, as explained with reference to Tables I and II.
At t=8.3 hrs, the heating means are disconnected from the mains and the autonomous operation begins. In view of the aforementioned results, shown in Tables III and IV above, it will be seen that after having achieved a regeneration of the reactor of the first system that was used to bring the interior of the enclosure to the setpoint temperature, the device contains a minimum of 187.7% ammonia in the form of gas at any time. Thus, if the device is disconnected from the mains after said regeneration phase, an autonomy of 59.3 hours is achieved. The autonomy is therefore increased compared to the “in opposition” operation explained previously.
| Number | Date | Country | Kind |
|---|---|---|---|
| 14 59333 | Oct 2014 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2015/052600 | 9/29/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2016/051076 | 4/7/2016 | WO | A |
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| Number | Date | Country |
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| Number | Date | Country | |
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| 20170299234 A1 | Oct 2017 | US |
