FR3141236A1 - Thermal machine - Google Patents

Abstract

A thermal machine (100) for the production of cold comprising a closed circuit comprising a compression means, a regulator (7) and a first heat exchanger (8), where the compression means comprises a lower sealed enclosure (1) filled with refrigerant and a second exchanger (4) allowing the circulation of a hot medium, in order to increase the temperature and pressure of the refrigerant, a high sealed enclosure (12) located higher than the lower sealed enclosure (1) , the lower sealed enclosure (1) and the upper sealed enclosure (12) being connected in the upper parts by a first pipe (18), selectively interruptible by means of a first solenoid valve (14), and in the lower parts by a second pipe (19), selectively interruptible by means of a second solenoid valve (15) and the upper sealed enclosure (12) further comprising a level detector (10) capable of controlling the solenoid valves (14, 15). Abstract figure: Figure 1

Description

Thermal machine

The invention relates to a thermal machine for the production of cold or cold group.

A heat engine for cold production can be made according to different known principles.

It is known the so-called absorption or adsorption principles, the Peltier effect principles, the desiccation principles.

One of the most efficient principles, offering the best performance, consists of using the expansion of a gaseous refrigerant fluid, previously compressed.

To exploit such a principle, a heat engine comprises a closed circuit, in which a refrigerant circulates. On this closed circuit are arranged, in sequence in the direction of circulation of the refrigerant, a compression means capable of sucking in the refrigerant at low pressure and low temperature, of compressing it to produce refrigerant at high pressure and high temperature, an expansion valve capable of expanding the refrigerant by reducing its pressure and a heat exchanger, capable of evaporating the refrigerant by producing cold, and of transmitting the refrigerant again by compression means.

The compression means is typically a mechanical compressor. Such a mechanical compressor has the main disadvantage of consuming significant energy which, in the case of electricity or fuel which may be fossil, is economically and/or ecologically expensive.

In addition, such a mechanical compressor is usually noisy, which creates noise pollution.

In addition, such a mechanical compressor is generally a machine with moving parts subject to wear and requiring lubrication, a source of pollution.

The need for cold, mainly air conditioning, has increased in recent years, due to an average rise in temperatures on the planet. The air conditioning market is growing rapidly. To cope with the electrical energy consumption of one million air conditioners, with a power of 1kW, it is necessary to build at least one additional nuclear power plant.

The invention proposes an alternative solution by replacing mechanical compression with compression of thermal origin, by obtaining with thermal energy, from a hot source, via a phase change of the refrigerant fluid, a significant expansion of the refrigerant fluid within a sealed enclosure.

The hot source is advantageously obtained from a medium preferably heated by solar energy, for example by means of a classic flat solar water heater. This then makes it possible to cool premises, including at night, with the hot medium stored in a tank.

This also makes it possible to achieve air conditioning by going from a significant cost in electrical energy to almost free energy.

This also allows for quiet air conditioning.

This also allows air conditioning to be achieved by thermal compression, eliminating moving parts and therefore all wear and lubrication.

For this, the invention relates to a thermal machine for producing cold comprising a closed circuit, in which a refrigerant circulates, comprising, in sequence in the direction of circulation of the refrigerant, a compression means capable of sucking in the refrigerant at low pressure and low temperature, of compressing it to produce refrigerant at high pressure and high temperature, an expansion valve capable of expanding the refrigerant by reducing its pressure and a first heat exchanger, between the refrigerant and a first medium, capable of evaporating the refrigerant by producing cold in the first medium, and of transmitting the refrigerant again to the compression means, where the compression means comprises a lower sealed enclosure filled with refrigerant in phase equilibrium and a second exchanger allowing the circulation of a second hot medium, in order to increase the temperature and the pressure of the refrigerant contained in the lower sealed enclosure, an upper sealed enclosure filled with refrigerant in phase equilibrium, located higher than the lower sealed enclosure, the lower sealed enclosure and the upper sealed enclosure being connected in the upper parts by a first pipe, selectively interruptible by means of a first solenoid valve, the lower sealed enclosure and the upper sealed enclosure being connected in the lower parts by a second pipe, selectively interruptible by means of a second solenoid valve and the upper sealed enclosure further comprising a liquid level detector capable of controlling the first solenoid valve and the second solenoid valve open for a high level and closed for a low level.

Particular features or embodiments, usable alone or in combination, are:
- the lower sealed enclosure is connected at the bottom, by a third pipe, to the inlet of the pressure reducer, the outlet of the pressure reducer is connected to the inlet of the first heat exchanger and the outlet of the first heat exchanger is connected to the upper sealed enclosure at the top,
- the upper watertight enclosure is located so that its lowest point is approximately halfway up the lower watertight enclosure,
- the liquid level detector includes a hysteresis to distance the high level from the low level,
- the liquid level detector comprises a float arranged in the upper sealed enclosure so as to float on the surface of the liquid, secured to a magnetic element capable of being magnetized and detected by a magnetic sensor arranged outside the upper sealed enclosure,
- the hysteresis is achieved by means of a rod, integral with the magnetic element, respectively with the float, sliding with distant stops in a sheath integral with the float, respectively with the magnetic element, the distance between the stops determining the extent of the hysteresis,
- the thermal machine also includes an additional sealed enclosure located higher than the upper sealed enclosure and connected by a fourth pipe in the upper part of the upper sealed enclosure,
- sealed enclosures are bottles comprising a single neck, arranged downwards, a connection in the lower part being made at the neck, in order to draw/fill liquid, and a connection in the upper part being made by a tube passing through the neck and rising towards the top of the bottle, in order to draw/fill gas,
- the second exchanger comprises a plurality of capillary tubes forming loops plunging into the lower sealed enclosure and emerging through a neck,
- the refrigerant is carbon dioxide, _CO2 ,
- the second medium is heated by a solar water heater and is preferably water,
- the lower sealed enclosure also includes a temperature sensor and/or a pressure sensor,
- the second medium is replaced by a third cold medium in order to cool the refrigerant when the refrigerant risks exceeding its critical temperature or pressure.

The invention will be better understood by reading the following description, given solely by way of example, and with reference to the appended figures in which:

shows, in schematic view, a heat engine according to the invention,

shows, in perspective view, a detail of the neck of a watertight enclosure,

shows, in a cut view along a vertical plane, a high watertight enclosure.

In reference to the , the invention relates to a thermal machine 100 for the production of cold. This thermal machine 100 is of the type by compression and expansion of a refrigerant fluid.

The heat engine 100 comprises a closed circuit, in which a refrigerant circulates. This circuit comprises, in sequence in the direction of circulation of the refrigerant, a compression means capable of sucking in the refrigerant at low pressure and low temperature, of compressing it to produce refrigerant at high pressure and high temperature. The refrigerant then joins an expansion valve 7 capable of expanding the refrigerant by reducing its pressure. The refrigerant then joins a first heat exchanger 8. This heat exchanger 8 is capable of exchanging between the refrigerant and a first medium. It is capable of evaporating the refrigerant. This produces cold which is transmitted to the first medium. Concomitantly, this evaporation/expansion heats the refrigerant. The first medium can be either directly the air of the room to be cooled or alternatively a heat transfer fluid allowing the transport of the frigories to the room to be cooled itself or another heat transfer fluid. As illustrated in , the cold is transmitted to a second closed circuit comprising a heat transfer fluid and ending at a diffuser 20. The circulation of heat transfer fluid is controlled by the solenoid valve 17.

Then the refrigerant is passed through the compression medium again, thus closing the circuit.

According to a characteristic of the invention, the compression means comprises a lower sealed enclosure 1 and an upper sealed enclosure 12.

The lower sealed enclosure 1 is filled with refrigerant in phase equilibrium, i.e. at a pressure and temperature such that the two phases, liquid and gaseous, coexist in the lower sealed enclosure 1. The first sealed enclosure 1 is equipped with a second exchanger 4. This second exchanger 4 comprises a closed circuit and allows the circulation of a second hot medium. The circulation of the second hot medium is controlled by the solenoid valve 16. This circuit is mainly immersed in a sealed manner and separated from the refrigerant in the interior of the first sealed enclosure 1, so as to allow the temperature, and consequently the pressure, of the refrigerant contained in the lower sealed enclosure 1 to be increased.

The high sealed enclosure 12 is filled with refrigerant in phase equilibrium, that is, at a pressure and temperature such that the two phases, liquid and gas, coexist in the high sealed enclosure 12.

The high waterproof enclosure 12 is located higher than the low waterproof enclosure 1.

In the present application, the term “connection in the upper part” means a connection to a sealed enclosure 1, 12, 11 in its upper part. Such a connection allows the connected pipe to open into the gaseous airspace of the sealed enclosure 1, 12, 11, and allows this pipe to draw or fill gas. Alternatively, the term “connection in the lower part” means a connection to a sealed enclosure 1, 12, 11 in its lower part. Such a connection allows the connected pipe to open into the liquid bottom of the sealed enclosure 1, 12, 11, and allows this pipe to draw or fill liquid.

The lower sealed enclosure 1 and the upper sealed enclosure 12 are connected by a first pipe 18 in the upper parts. The first pipe 18 is connected in the upper part of the lower sealed enclosure 1, and in the upper part of the upper sealed enclosure 12. The first pipe 18 is equipped with a first solenoid valve 14, making it possible to selectively connect or interrupt the connection between the gaseous spaces of the two sealed enclosures 1, 12.

The lower sealed enclosure 1 and the upper sealed enclosure 12 are further connected by a second pipe 19 in the lower parts. The second pipe 19 is connected in the lower part of the lower sealed enclosure 1, and in the lower part of the upper sealed enclosure 12. The second pipe 19 is equipped with a second solenoid valve 15, making it possible to selectively connect or interrupt the connection between the liquid bottoms of the two sealed enclosures 1, 12.

As detailed in the , the high sealed enclosure 12 also comprises a liquid level detector 10. This level detector 10 is used to control the first solenoid valve 14 and the second solenoid valve 15. Upon detection of a high level, the two solenoid valves 14, 15 are controlled to the open position. Upon detection of a low level, the two solenoid valves 14, 15 are controlled to the closed position.

According to another characteristic, the lower sealed enclosure 1 is connected, in the lower part, by a third pipe 6, to the inlet of the pressure reducer 7. Thus, in the event of an increase in the pressure in the lower sealed enclosure 1, the liquid contained in the lower sealed enclosure 1 is pushed and directed towards the pressure reducer 7.

In addition, the outlet of the expansion valve 7 is connected to the inlet of the first heat exchanger 8. Then, the outlet of the first heat exchanger 8 is connected to the upper sealed enclosure 12 in the upper part, via an outlet 9.

As visible on the , the connection via the third line 6 between the lower sealed enclosure 1 and the pressure reducer 7 is a permanent connection. The tapping of the third line 6 is made to the left of the solenoid valve 15.

According to another characteristic, the high sealed enclosure 12 is located so that its lowest point is approximately halfway up the low sealed enclosure 1. This difference in relative altitude allows, when the solenoid valve 15 is open, the liquid present in the high sealed enclosure 12 to flow by gravity towards the low sealed enclosure 1, until the levels are equalized.

In order to initialize the heat engine 100, the closed circuit formed by the sealed enclosures 1, 12, 11 is filled with refrigerant fluid in such a way that the two sealed enclosures, lower 1 and upper 12, contain refrigerant fluid in liquid form. Thus, at room temperature (for information purposes 20 to 25°C), a pressure of 57 bars is retained for a refrigerant fluid composed of carbon dioxide _CO2 .

The compression method described above works as follows. Its operation is cyclical. Also, the description of the cycle can be done from any event.

The operation is based on a cycle materialized by transfers of refrigerant fluid from a low sealed enclosure 1, in which there is high pressure, to a high sealed enclosure 12 in which the pressure is lower.

Let us assume that we start the description of the operating cycle when solenoid valves 14, 15 open.

A liquid is substantially incompressible. Also, the fact that the solenoid valve 15 is open causes the liquid contained in the two sealed enclosures 1, 12 to flow from one to the other, by communicating vessel effect, until the level 2 in the lower sealed enclosure 1 is equal to the level 3 in the upper sealed enclosure 12, as illustrated in .

Although level 2 is equal to level 3 in absolute terms, since the high sealed enclosure 12 is located at a higher altitude than the low sealed enclosure 1, the relative level, i.e. the filling level, is much higher in the low sealed enclosure 1 than in the high sealed enclosure 12.

The fact that the first solenoid valve 14 is open causes the gas pressures to balance between the two sealed enclosures 1, 12. The gas pressure in the lower sealed enclosure 1 is thus equal to the gas pressure in the upper sealed enclosure 12. This equalization of pressures also causes significant cooling in the lower sealed enclosure 1, which was at high pressure, which is beneficial for the rest of the cycle.

When balancing the gas pressures by opening the first solenoid valve 14, the pressure is such that, at room temperature, the refrigerant is in liquid phase in the two sealed enclosures, the lower sealed enclosure 1 and the upper sealed enclosure 12.

The flow of liquid via the solenoid valve 15 generally takes place from the upper sealed enclosure 12 to the lower sealed enclosure 1. The drop in the liquid level makes it possible to reach a low liquid filling level of the upper sealed enclosure 12. This low level is detected by the level detector 10 which consequently controls a closing of the two solenoid valves 14, 15.

When the solenoid valves 14, 15 are closed, the lower sealed enclosure 1 is filled with refrigerant fluid, mainly in liquid form and having a high density, advantageously between 0.8 and 0.9 g per cm ³ . The high-density refrigerant fluid is all the more sensitive to even a small temperature rise, which produces a very high pressure, due to the insulation of the lower sealed enclosure 1.

The refrigerant contained in the lower sealed enclosure 1, now isolated from the upper sealed enclosure 12, by the closing of the first solenoid valve 14 and the second solenoid valve 15, is heated by contact with the second hot medium circulating in the second exchanger 4.

Under the effect of this heating, the pressure in the lower sealed enclosure 1 increases significantly. A temperature rise of a few degrees Celsius causes, at the density where the refrigerant is found, a significant rise in pressure at the level of the gaseous ceiling of the lower sealed enclosure 1.

The latter applies a thrust to the liquid contained in the lower sealed enclosure 1 which carries it via the third pipe 6 towards the inlet of the regulator 7.

Depending on the need for cold production, the expansion valve 7 lets said liquid escape so that it reaches the heat exchanger 8 or evaporator. The expansion of the refrigerant produces cold at the first heat exchanger 8 and the refrigerant leaves the first heat exchanger 8 in gaseous form. The outlet of the heat exchanger 8 is connected to the upper sealed enclosure 12. Thus, the refrigerant in gaseous form reaches the upper sealed enclosure 12 via the outlet 9.

When it reaches the upper sealed enclosure 12, said gas joins the gaseous sky of the upper sealed enclosure 12 which is at a lower density and pressure. The lowering of the temperature in the upper sealed enclosure 12 allows the liquefaction of the refrigerant . Also, the liquid level in the upper sealed enclosure 12 increases accordingly. This increase in the liquid level does not have a significant effect on the gas pressure, because the density of the refrigerant is very low in the upper sealed enclosure 12. The liquid level increases until it reaches a high liquid level. This high liquid level is detected by the level detector 10 which then controls the opening of the first and second solenoid valves 14, 15.

The cycle is complete here. It then repeats itself, almost identically.

In order to properly separate the event of opening the solenoid valves 14, 15 and the event of closing the solenoid valves 14, 15, according to another characteristic, the liquid level detector 10 includes a hysteresis in order to distance the high level from the low level.

According to another feature, the level detector 10 is based on a float placed in the high watertight enclosure 12 in order to float on the surface of the liquid. For this, as illustrated in , the level detector 10, 301 comprises a float 310 capable of floating on the surface of the refrigerant liquid. This float 310 is integral with a magnetic element 313 and drives it in its vertical movement when it rises or falls with the liquid level. This magnetic element 313 is capable of being magnetized and detected by a magnetic sensor 314. This magnetic sensor 314 is advantageously arranged outside the upper sealed enclosure 12.

Advantageously, the float 310 is made of flexible material in order to allow its deformation to allow it to pass through the neck 303 of the upper watertight enclosure 12, this deformation being reversible in order to allow it to then return to its initial shape.

According to another characteristic, the hysteresis is achieved by means of a rod 312, integral with one of the elements among the magnetic element 313 or the float 310, sliding with distant stops in a sheath 311 integral with the other of the elements among the float 310 and the magnetic element 313.

Thus, when the float 310 rises with the liquid level, it carries with it the body 307, the sheath 311 and the rod 312 in the folded position in the sheath 311. The rod 312 is at the bottom stop, its proximal end resting against the body 307.

When the magnetic element 313, carried by the distal end of the rod 312, comes into contact with the roof of the upper sealed enclosure 12, it is magnetized and is detected by the magnetic sensor 314. This corresponds to the high liquid level.

This configuration controls the opening of solenoid valves 14, 15, which stops the rise in the liquid level and causes the said level to fall, by gravity flow.

When the liquid level drops, the float 310 descends again. It carries with it the body 307 and the sheath 311 secured to the body 307. The rod 312, still magnetized, remains in the high position in contact with the roof of the upper sealed enclosure 12. It remains magnetized to the roof and deploys out of the sheath 311 until the rod 312 comes to the high stop, its proximal end in contact against the distal part of the sheath 311 which attracts it downwards and stops the magnetization, when the float 310 reaches the low liquid level.

The distance between the two stops, approximately the length of the rod 312, determines the extent of the hysteresis and the distance between the low level and the high level.

According to another characteristic, more particularly illustrated in the , the heat engine 100 also comprises an additional sealed enclosure 11. This additional sealed enclosure 11 is located higher than the upper sealed enclosure 12 and is connected by a fourth pipe 13 in the upper part of the upper sealed enclosure 12. This connection is advantageously permanent. The tapping of the fourth pipe 13 is arranged to the right of the solenoid valve 14.

This additional sealed enclosure 11 is intended to accommodate only gas. It serves as an extension to the upper sealed enclosure 12. It makes it possible to increase the volume capable of accommodating gas. This makes it possible to reduce the density of the refrigerant and thus promotes the liquefaction of the refrigerant returning from the first exchanger 8 in gaseous form.

According to another characteristic, the additional sealed enclosure 11 is located so that its lowest point is approximately halfway up the upper sealed enclosure 12.

The sealed enclosures 1, 12, 11 can be made by any means in any material capable of withstanding pressure. They can thus be made of composite material, metallic material or even concrete.

According to another characteristic, at least one of the sealed enclosures 1, 12, 11, and advantageously all, are bottles capable of withstanding pressure. Each bottle comprises a single neck 303. This neck 303 is arranged downwards.

A connection in the lower part is then made at the level of the neck 303. Such a connection then makes it possible to draw/fill liquid. A connection in the upper part could be made by a second neck arranged in the upper part of the sealed enclosure.

However, in order to limit the necks and advantageously reuse existing bottles or tanks, on the contrary, a connection in the upper part is made by passing through the single neck 303, by means of a tube passing through the neck 303 and rising towards the top of the bottle. Such a connection makes it possible to draw/fill gas.

Advantageously, these bottles reuse diving bottles, capable of withstanding a pressure of 300 bars, typically made of aluminum.

As detailed in the , detailed view of the neck of the lower sealed enclosure 1, the second exchanger 4 comprises a plurality of capillary tubes 204. These capillary tubes 204 pass through the neck 303. They are looped by connection in pairs in order to allow circulation in the volume of the lower sealed enclosure 1 from a pump arranged outside the lower sealed enclosure 1.

The capillary tubes 5, 204, 205 are advantageously made of a material with high thermal conductivity, such as copper, Cu or aluminum.

According to another characteristic, the refrigerant is carbon dioxide, CO ₂ . This refrigerant is advantageous in that it has physical characteristics and in particular a change of state that are particularly suited to the operation of the present thermal machine 100. In addition, CO ₂ advantageously has characteristics that are among the least harmful in terms of greenhouse gases, GHGs.

According to another characteristic, the second hot medium which provides its heat energy to the refrigerant in the second exchanger 4, is heated by a solar water heater. This heating of the refrigerant being the only external energy supply to the heat engine useful for operating the compression means, such substantially free heat energy advantageously makes it possible to produce substantially free cold.

Solar heating is one possibility. Alternatively, while retaining the advantage of being free, the heat can be provided by a naturally hot source, heat recovery from an industrial process, for example from a nuclear power plant or even geothermal energy.

Furthermore, neither the heating of the second hot medium nor the operation of the compression means of the invention produces noise. Also the thermal machine is advantageously silent.

The second hot medium can be any heat transfer fluid. For example, it can be glycolated water or glycol. The second medium is preferably water.

According to another characteristic, the low sealed enclosure 1 also comprises a temperature sensor and/or a pressure sensor.

According to another characteristic, the temperature sensor is a thermocouple advantageously arranged in a blind capillary 5, 205, solitary and arranged across the neck 303 like the capillaries 204 of the second exchanger 4. As illustrated in , this capillary 5 is advantageously arched so as to move the thermocouple away from the other capillaries 204 where the second hot medium circulates and not to disturb the measurement by the heat provided by the second hot medium via the second exchanger 4.

The pressure sensor (not shown) can be placed on a pipe connected to the lower sealed enclosure 1 in the upper part.

The temperature or pressure sensor is advantageously used to secure the heat engine 100 by preventing the refrigerant from reaching a critical temperature or pressure. Thus, in the case of a CO ₂ refrigerant, the critical temperature is 31 °C. Similarly, there is a critical pressure that can be observed by means of the pressure sensor.

Also, as soon as critical conditions are approached, and preferably before, the second exchanger 4 is used to cool the refrigerant. For this, the second hot medium is replaced by a third cold medium.

This third cold medium can typically come from the network water supply which generally has a temperature below 20°C and can be used to cool in order to safeguard the thermal machine 100.

The pressure sensor can be used to secure the compression medium so that the critical pressure is not exceeded, as described previously.

The pressure sensor can still be used to trigger a cycle reset and a balancing of the liquid levels 2, 3 and the pressures between the lower sealed enclosure 1 and the upper sealed enclosure 12. In this case, this pressure sensor observes the pressure and when the pressure becomes lower than a predetermined threshold value, the opening of the solenoid valves 14, 15 is controlled. In this case, the pressure sensor replaces the level detector 10 for the detection of a high level. The closing of the solenoid valves 14, 15 remains controlled by the detection of a low liquid level by means of the level detector 10. The predetermined pressure threshold value is determined from a pressure relationship produced as a function of the heating time, for a value beyond which the quantity of heat to be supplied by the exchanger 4 becomes too great, leading to a lower efficiency of the compression means and the heat engine 100.

The invention has been illustrated and described in detail in the drawings and the preceding description. The latter should be considered as illustrative and given by way of example and not as limiting the invention to this description alone. Numerous variant embodiments are possible.

Claims (13)

Heat engine (100) for producing cold comprising a closed circuit, in which a refrigerant circulates, comprising, in sequence in the direction of circulation of the refrigerant, a compression means capable of sucking in the refrigerant at low pressure and low temperature, of compressing it to produce refrigerant at high pressure and high temperature, an expansion valve (7) capable of expanding the refrigerant by reducing its pressure and a first heat exchanger (8), between the refrigerant and a first medium, capable of evaporating the refrigerant by producing cold in the first medium, and of transmitting the refrigerant again to the compression means, characterized in that the compression means comprises a lower sealed enclosure (1) filled with refrigerant in phase equilibrium and a second exchanger (4) allowing the circulation of a second hot medium, in order to increase the temperature and the pressure of the refrigerant contained in the lower sealed enclosure (1), a high sealed enclosure (12) filled with refrigerant in phase equilibrium, located higher than the lower sealed enclosure (1), the lower sealed enclosure (1) and the upper sealed enclosure (12) being connected in the upper parts by a first pipe (18), selectively interruptible by means of a first solenoid valve (14), the lower sealed enclosure (1) and the upper sealed enclosure (12) being connected in the lower parts by a second pipe (19), selectively interruptible by means of a second solenoid valve (15) and the upper sealed enclosure (12) further comprising a liquid level detector (10) capable of controlling the first solenoid valve (14) and the second solenoid valve (15) open for a high level and closed for a low level. Heat engine (100) according to claim 1, where the lower sealed enclosure (1) is connected in the lower part, by a third pipe (6), to the inlet of the expander (7), where the outlet of the expander (7) is connected to the inlet of the first heat exchanger (8), and where the outlet of the first heat exchanger (8) is connected to the upper sealed enclosure (12) in the upper part. Thermal machine (100) according to any one of the preceding claims, wherein the upper sealed enclosure (12) is located so that its lowest point is substantially halfway up the lower sealed enclosure (1). A heat engine (100) according to any preceding claim, wherein the liquid level detector (10) comprises a hysteresis to distance the high level from the low level. Thermal machine (100) according to any one of the preceding claims, wherein the liquid level detector (10) comprises a float (310) arranged in the upper sealed enclosure (12) so as to float on the surface of the liquid, integral with a magnetic element (313) capable of being magnetized and detected by a magnetic sensor (314) arranged outside the upper sealed enclosure (12). Heat engine (100) according to any one of claims 4 or 5, where the hysteresis is achieved by means of a rod (312), integral with the magnetic element (313), respectively with the float (310), sliding with distant stops in a sheath (311) integral with the float (310), respectively with the magnetic element (313), the distance between the stops determining the extent of the hysteresis. Thermal machine (100) according to any one of the preceding claims, further comprising an additional sealed enclosure (11), located higher than the upper sealed enclosure (12) and connected by a fourth pipe (13) in the upper part of the upper sealed enclosure (12). Thermal machine (100) according to any one of the preceding claims, where the sealed enclosures (1, 12, 11) are bottles comprising a single neck (303), arranged downwards, a connection in the lower part being made at the neck (303), in order to draw/fill liquid, and a connection in the upper part being made by a tube passing through the neck (303) and rising towards the top of the bottle, in order to draw/fill gas. Thermal machine (100) according to any one of the preceding claims, where the second exchanger (4) comprises a plurality of capillary tubes forming loops plunging into the lower sealed enclosure (1) and emerging through a neck (303). A heat engine (100) according to any preceding claim, wherein the refrigerant is carbon dioxide, CO ₂ . A heat engine (100) according to any preceding claim, wherein the second medium is heated by a solar water heater and is preferably water. Thermal machine (100) according to any one of the preceding claims, wherein the low sealed enclosure (1) further comprises a temperature sensor and/or a pressure sensor. A heat engine (100) according to any preceding claim, wherein the second medium is replaced by a third cold medium to cool the refrigerant when the refrigerant is at risk of exceeding its critical temperature or pressure.