WO2018007963A1

WO2018007963A1 - Thermo-machine using a work fluid in an open cycle

Info

Publication number: WO2018007963A1
Application number: PCT/IB2017/054057
Authority: WO
Inventors: Davide GIOBBIO
Original assignee: Giobbio Davide
Priority date: 2016-07-05
Filing date: 2017-07-05
Publication date: 2018-01-11
Also published as: IT201600069585A1

Abstract

A thermo-machine that uses a work fluid in an open cycle; the thermo-machine comprises: a compressor (1) to pressurize the work fluid (2) taken from the outside by carrying out an isothermal compression; a heat exchanger (3; 3a) comprising a first circuit, which receives the work fluid (2) flowing out of the compressor (1), and a second circuit, which is fluidically insulated from and thermally coupled to the first circuit; a first turbine (4), which receives the work fluid (2) flowing out of the first circuit of the heat exchanger (3; 3a); and a second turbine (7), which receives the work fluid (2) flowing out of the second circuit of the heat exchanger (3; 3a); wherein the work fluid (2) flowing out of the first turbine (4) flows through the second circuit of the heat exchanger (3; 3a) so as to be heated by the work fluid (2) flowing out of the compressor (1); and wherein the residual work fluid (10) flowing out of the second turbine (7) is released into the external environment at a temperature that is lower than the temperature of the work fluid (2) flowing into the compressor (1).

Description

"THERMO-MACHINE USING A WORK FLUID IN AN OPEN CYCLE" TECHNICAL FIELD

The present invention relates to a thermo-machine, or thermal machine, designed to produce mechanical work by using the heat in a work fluid, in an open cycle.

The present invention finds advantageous application in a thermal machine that uses atmospheric air as a work fluid (using the heat present in the atmosphere due to solar heating) , to which the following description will make explicit reference without any loss of generality.

PRIOR ART

The type of machine forming the subject of the present invention is that theorized by Nikola Tesla in the famous treatise "The problem of increasing human power", published in 1900 by "Century Magazine" of New York, from which the possibility can be inferred of making a "self-acting engine" , capable of using the solar energy present in the atmosphere for becoming self-sustaining; however, there are indications in the same article foreseeing that the existing mechanical solutions would lead to results of assured benefit, but not so sensational (the machine, using pistons, would have had the problem as that of Bob Neal, described below) . Tesla continued to pursue his dream, patenting several machines known today as the Tesla turbine/pump/compressor/decompressor, based on the principle of adhesion and viscosity of fluids and gases, and capable of eliminating the defects encountered in piston engines. At the same time as the patents for the aforementioned machines, a patent application was filed with the title "Method of and Apparatus for Thermo-Dynamic Transformation of Energy" (application No. 533,524 of 02/02/1922), which presumably contained the assembly sequence of the aforementioned machines for obtaining energy from environmental heat, with the respective specifications; the scientist's financial difficulties at that time prevented pursuing this patent application, which was abandoned without being granted. Patent US2030759, filed by Bob Neal and published in 1934, protects an engine/compressor based on the same principle set out by Tesla, with the conceptual limitation of using a piston system, where the low temperature generated by adiabatic expansion presumably tended to "freeze" the pistons; in consequence, this patent provided an in-line heater to limit damage, which however causes a large drop in the application's usable residual energy.

DESCRIPTION OF INVENTION

The object of the present invention is to provide a thermo- machine designed to produce mechanical work, in and an effective and efficient manner, by using the heat in a work fluid in an open cycle. According to the present invention a thermo-machine is provided that is designed to produce mechanical work by using the heat in a work fluid in an open cycle, as claimed in the appended claims. BRIEF DESCRIPTION OF DRAWINGS

The present invention will now be described with reference to the accompanying drawings, which illustrate a non-limitative embodiment, in which:

• Figure 1 schematically represents a thermo-machine that is made according to the present invention and is designed to produce mechanical work by using, in an open cycle, the heat in atmospheric air;

• Figures 2-6 show a first embodiment of a superheating system based on magnetic induction, with associated feed circuits;

• Figure 7 shows a second embodiment of a superheating system based on magnetic induction and eddy currents;

• Figures 8-11 show a third embodiment of a superheating system based on magnetic or electromagnetic induction and the generation of heat by exploiting the hysteresis of iron;

· Figure 12 shows a fourth embodiment of a superheating system based on an electromagnetic ray concentrator, the rays being solar rays in the example;

• Figure 13 shows a fifth embodiment of a superheating system based on a heat exchanger with a combustion chamber; · Figure 14 shows a sixth embodiment of a superheating system based only on airflows and composed of an air amplification valve upstream of a Ranque-Hilsch vortex tube;

• Figure 15 schematically represents a variant of the thermo-machine in Figure 1; and

· Figure 16 schematically represents a compressor of the thermo-machine in Figure 1.

PREFERRED EMBODIMENTS OF THE INVENTION

Figure 1 shows, as a whole, a thermo-machine designed to produce mechanical work by using, in an open cycle, the heat in a work fluid and, in particular, in atmospheric air, using the heat present in the atmosphere due to solar heating.

In its base implementation, the thermo-machine comprises a compressor 1 (passive, volumetric, reciprocating or dynamic, possibly with multiple stages or a combination thereof) to pressurize the work fluid 2, constituted by atmospheric air and taken from the external environment at ambient temperature. The work consumed by this compression is partially transformed into heat (excluding the negligible percentage from friction) which is extracted by a heat exchanger 3; in particular, the heat exchanger 3 comprises a first circuit through which the work fluid 2 leaving the compressor 1 passes. The work fluid 2 leaves the first circuit of the heat exchanger 3 at a lower temperature than the inlet temperature at the heat exchanger 3 and expands to full expansion in a (possibly multistage) turbine 4.

Not being able to exchange, ideally, heat with the environment, the work produced by expansion in the turbine 4 is taken from the heat of the internal energy of the work fluid 2 that is expelled in the duct 5 at tens of degrees below the inlet temperature (which is the ambient temperature) . The problem of crystallization of humidity naturally present in the work fluid 2 (i.e. in atmospheric air) is solved by the type of turbine 4 used, able to handle and expel solid bodies. Downstream of the turbine 4, namely on an exhaust duct 5 of the turbine 4, a decompression device 6 is mounted that, by creating a vacuum in the exhaust duct 5, allows the work fluid 2 to give up further heat by expanding below the atmospheric pressure. The thus-cooled work fluid 2 is sent to the heat exchanger 3, where it absorbs the heat of the initial compression, thereby increasing in pressure; in particular, the work fluid 2 that leaves the decompression device 6 passes through a second circuit of the heat exchanger 3 that is fluidically insulated from the first circuit (i.e. does not exchange work fluid 2 with the first circuit) and is thermally coupled to the first circuit (i.e. exchanges heat with the first circuit) . In particular, heat is transferred from the first circuit to the second circuit of the heat exchanger 3 to heat the work fluid 2 coming from the decompression device 6, consequently cooling the work fluid 2 coming from the compressor 1.

The work fluid 2 that leaves the second circuit of the heat exchanger 3 is then conveyed to a second, possibly multistage, turbine 7, where the expansion process is repeated; in this case as well, downstream of the turbine 7, namely on an exhaust duct 8 of the turbine 7, another decompression device 9 can be optionally mounted that, by creating a vacuum at the exhaust duct 8, allows the work fluid 2 to give up further heat by expanding below the atmospheric pressure. The residual work fluid 10 is released from the decompression device 9 into the external environment or partly put back in circulation. Multiple cycles of expansion, heating and compression can be used, if necessary resorting to other exchangers that exchange heat with the atmosphere, or other heat sources (for example, the coolant fluid of other machinery, burners,...) or one of the other systems listed below (and shown in Figures 2-14) . Figure 15 shows a different embodiment of the thermo-machine, which differs from the thermo-machine shown in Figure 1 for the absence of the decompression devices 6 and 9 and for the presence of two heat exchangers 3a and 3b respectively arranged upstream and downstream of the turbine 4. Heat exchanger 3a is entirely similar to the previously described heat exchanger 3, while heat exchanger 3b heats the air leaving the turbine 4 to ambient temperature using the heat in the external environment (i.e. it absorbs heat from the external environment to heat the air leaving the turbine 4) .

The thermodynamic transformations through which the transformation of heat energy in the work fluid 2 (i.e. in the environmental medium) into mechanical work is achieved can, by non-exhaustive way of example, be isothermal compression (where the extracted heat is recovered in the heat exchanger 3), adiabatic expansion that takes the work fluid 2 to a low density and low pressure, isobaric heating in the heat exchanger 3, isochoric compression by means of dynamic compression (nozzle), and another adiabatic expansion. It is important to clarify that the cycle is not a closed cycle, i.e. the work fluid 2 enters the thermo-machine with a certain amount of heat (temperature) and exits the thermo-machine with less heat (temperature) , or exchanges heat with the environment, which thus gives up energy, to raise its temperature. Therefore, the thermo-machine does not fall within the scheme of a thermodynamic cycle that strictly provides a closed cycle; in fact, as the thermo-machine is fuelled by environmental heat, should the ambient temperature tend to absolute zero, fuel for the thermo-machine (atmospheric heat) would run out and so the thermo-machine would stop. A waterfall used to produce electricity is a classic example of an open cycle: in particular, only the descending part of a closed cycle is exploited. It is important to underline that in an open cycle, it is not possible to invoke the second law of thermodynamics, which applies solely and exclusively to closed cycles, i.e. those cycles in which the initial and final states of the work fluid coincide. Like a waterfall, the above-described thermo-machine extracts atmospheric heat, transforming it into work. No hydroelectric power station worries about returning the water to its original height, this disadvantageous work being left to solar heat, evaporation, atmospheric cooling and rain. In the same way, the above- described thermo-machine does not concern itself with heating the atmosphere, already heated by the sun and overheated by normal closed cycles through entropy.

It is necessary to stress that the conversion process is not spontaneous: to activate the above-described thermo-machine it is necessary to initially provide work. Furthermore, favourable efficiency is not a foregone conclusion, strongly depending on the concentration of environmental heat, i.e. ambient temperature. As no law of thermodynamics is violated, perpetual motion can be excluded a priori. The transformations that the fluid undergoes are classical thermodynamic transformations, subjected to state changes ideally deduced from the laws of thermodynamics applied to the ideal gas law. Air, being a diatomic gas for 99% of its composition, adapts to the ideal model in a reasonably close manner, even more so at low pressures. In the examples that follow, it has been envisaged that the machine has an airflow rate of 1 m³/sec, i.e. every second, 1 m³ of atmospheric air is processed, extracting work and returning the air to the environment at point distant from the inlet point and at a temperature many degrees below the inlet temperature (i.e. ambient temperature) . Thinking that this removal of heat cannot be transformed into mechanical work would be a manifest violation of the first law of thermodynamics.

According to a possible, but not limitative, embodiment, the residual work fluid 10 (possibly even in the liquid state if the outlet temperature was below -196°C) of the expansion states (i.e. the residual work fluid 10 leaving the decompression device 9) can be recovered to supply cooling systems or refrigeration systems connected to the outlet of the thermo-machine, eliminating the energy consumption of these systems, or even transformed into liquid air. According to a possible, but not limitative, embodiment, a minimum part of the residual work fluid 10 can be mixed with work fluid 2 coming from the external environment by means of a non-return valve 11 on the outlet of the compressor 1 to increase the efficiency of the isothermal compression. In other words, a recirculation line can be provided that draws off a fraction of the residual work fluid 10 released into the external environment and feeds it between the compressor 1 and the first circuit of the heat exchanger 3 through a non-return valve 11 arranged on the outlet of the compressor 1. According to a possible, but not limitative, embodiment, it is possible to recover the cold from one of the heat exchangers that remove heat from the environment, possibly recirculating it by means of a Venturi tube. According to a possible, but not limitative, embodiment, it is possible to recover the residual heat from one of the heat exchangers that form the thermo- machine or from a hot outlet and concentrate it with a Ranque- Hilsch vortex tube at the inlet of the turbines 4 and/or 7 to increase efficiency. According to a possible, but not limitative, embodiment, it is possible to place one of the heat exchangers that form the thermo-machine, with suitably pipework, before the inlet of the compressor 1, in order to exchange heat given up or absorbed by the work fluid with the atmospheric air entering the thermo-machine (i.e. entering the compressor 1 ) . According to a preferred embodiment, an engine is provided that is designed to generate mechanical energy (for example, by absorbing electric energy) and is connected to the compressor 1 to drive the compressor 1, and, for each turbine 4 or 7, at least one generator is provided that absorbs mechanical energy from the turbine 4 or 7. According to a possible, but not limitative, embodiment, the engine is an electric motor and the at least one generator is an electric generator that produces the electric energy that powers the motor; it is important to clarify that the electric energy generated by the generators is greater than the electric energy absorbed by the motor and the difference between the electric energy generated by the generators and the electric energy absorbed by the motor constitutes the "useful" energy produced by the thermo-machine.

The total thermal gradient created generates surplus mechanical work with respect to the initial energy of the system, and this surplus of mechanical work is (according to the first law of thermodynamics) equal to the amount of heat removed from the work fluid 2 between the inlet and the outlet of the thermo-machine multiplied by the mass of work fluid 2 processed, increased by the work generated due to all the heat transfers with the environment. For the purpose of giving a realistic estimate of the possibilities of the above-described thermo-machine, the base transformation sequence is assumed and the ideal theoretical physical behaviour is analysed (referring to embodiment of the thermo-machine shown in Figure 15) . The thermo-machine shown in Figure 15 is composed of a compressor 1, an expansion turbine 4, an expansion turbine 7, a heat exchanger 3a arranged upstream of turbine 4, and a heat exchanger 3b arranged downstream of turbine 4 (i.e. between turbine 4 and the second circuit of heat exchanger 3a) .

It is assumed to transform 1 m³ of atmospheric air per second, and consequently, on average, at a temperature of 288.11°K (approximately 15°C) and a pressure of 101325 Pa (i.e. 1 atm, equal to the pressure exerted by earth' s atmosphere at sea level) . The initial internal energy (U = 253315 J) of the processed air mass is given by the following equation:

U = n-CvT= 42.2997 x (5/2 x 8.3143) x 288.11 = 253315 J

The following are defined for the transformations:

Q = heat exchanged;

Δυ = change in internal energy of the fluid being processed (ambient air) ;

L = work done by/on the gas.

The first transformation is an isothermal one by the volumetric compressor 1 and the associated heat exchanger 3b. Assuming that the compression ratio is 1:6, the air is compressed to 607945 Pa. As, in a first approximation, the temperature of the fluid is constant, the work introduced is completely exchanged with the environment, in this case by means of the heat exchanger 3b. The volume V₂ of the gas in the final state is calculated using the Boyle-Mariotte Law:

P-V = constant Pi-Vi P₂-V₂

Therefore :

Work done on the gas from the ideal gas laws:

substituting :

J 101325 Pa

I^ ₂= 142,2997 mol l 8, 3143 x 1288, 11 X1 In 181551 J

mol · 607945 Pa according to the first law of thermodynamics

since the temperature is constant and hence Δυ

= L, and therefore:

This means that the compression work transforms into heat "conserved" in heat exchanger 3a.

This is followed by adiabatic expansion in the turbine 4 for returning the pressure to 101325 Pa. In an adiabatic transformation, Q=0 is assumed, and therefore AU = -L, i.e. the expansion uses the heat energy in the air to produce work. The adiabatic transformation is described by the following Poisson equation:

Ρ-Ψ = constant where is the ratio between the specific heats at

constant pressure and volume.

The gas equation in the two states 1 and

Ρι·Υι^γ = Ρ₂·ν₂ ^γ

Knowing that air is a 99% diatomic gas, the relevant values are substituted: V₂- (0,166668 m

The temperature of the air in the final state is obtained from the ideal gas law:

n-R

142,2997 mol) 8,3143

mol - K the change in internal energy is:

substituting the values gives:

ΔΙΙ, ,= 42,2997 molx -x 8,3143 x (172,67 K - 288,11 K l= - 101498 J

2 mol - Jv

Given that Q=0 in the adiabatic transformation, the first law of thermodynamics results in the following reduction:

substituting the values gives:

Li→2 = - AUi→2 = - (-101498 J) = + 101498 J

Therefore, the turbine 4 has generated mechanical work for 101498 J. it should be noted that, although returning to 1 atm, the volume of the fluid remains smaller at 0.59934, having lost heat. Returning the fluid to atmospheric temperature with constant volume, gives a pressure advantage.

The third transformation is isochoric heating that takes place in two phases: an initial phase (from a temperature of 172.67°K to an atmospheric temperature of 288.11°K), which takes place in heat exchanger 3b (isochoric, i.e. at constant volume), and a final phase (from an atmospheric temperature of 288.11°K to a temperature of 494.59°K), which takes place in heat exchanger 3a (isochoric, i.e. at constant volume), where the heat of the compression carried out by the compressor 1 is recovered. In other words, heat exchanger 3b returns the fluid from the temperature of 172.67°K to atmospheric temperature (288.11°K) and, successively, heat exchanger 3a, where the compression heat is recovered, takes the temperature of the fluid from atmospheric temperature (288.11°K) to 494.59°K, always with constant volume.

The heat necessary for making the first jump and reach temperature T₂ of 15°C (288.11°K) by means of heat exchanger 3b, which transfers atmospheric energy to the fluid without using work, but by cooling the atmosphere, will now be calculated .

substituting :

Q -( 42,2997 moll * - 8,3143— ^J-— x fl^'288,11 K] - i l72,67^'ll = 101498 J

' 2 niol - K J ^{l '} '

The fluid leaves at 15°C (288.11°K) : now the heat exchanged (Qc = 181551 J) in the isothermal transformation of the initial compression is recovered, recovering it from heat exchanger 3a. This is the phase in which, ideally, all the work introduced, and a surplus of energy taken from the atmosphere, which no known machine recovers, according to the experience of the applicant, is recovered in mechanical form.

Final temperature: assuming total (theoretical) heat exchange in the system, the following is derived from the previous formula :

substituting the values gives 172,67 K = 494,59 K = 221,45° C

Final pressure after isochoric heating:

which ives

The fluid, now pressurized at 290231 Pa (2.86 atm) , is expanded by multistage turbine 7, by means of a further adiabatic transformation, which takes the volume to:

and takes the temperature

Therefore :

J

Δυ, ,= 42,^J2997 mol x-1 8, 3143 x (366,17 K - 494,59 Kl = -112910 J

mol - K

The work done by the gas is obtained by substituting the values :

- AU_1→2 = -(-112910 J) = + 112910 J

Thus, the expansion in turbine 7 has (theoretically) generated mechanical work on the turbine's shaft equal to + 112910 J. The result of the series of transformations is:

A cold point at 172.67°K in heat exchanger 3a and usable for cooling an industrial freezer, as a source for a passive compressor, or as a cold point for a Stirling engine.

A hot point at the exhaust outlet of the work fluid 10 at 366.17°K that can be alternatively used for domestic heating or from which it is possible to extract mechanical work (using a closed-cycle Sterling engine with 23% efficiency, a further 74 KW of mechanical power can be obtained) .

Mechanical work deriving from the difference between the work generated by the turbines 4 and 7 and that absorbed by the compressor 1 (assuming, ideally and in a first approximation, of not having losses in the transformation from mechanical energy to electric energy and vice versa) :

(101498+112910) - 181551 = 32.857 J/s (roughly 32 KW)

Adding the recovery of the aforementioned Stirling engine (theoretical Carnot efficiency 52.8%, real efficiency 23%) gives a further 74kW for a total achievable mechanical power equal to approximately 106 KW (i.e. 106 kWh of work/energy every hour) by processing 1 m³ of atmospheric air per second.

This calculation serves to demonstrate in a purely theoretical manner how, with an ambient temperature of approximately 15°C (288.11°K), the above-described thermo-machine produces mechanical energy in surplus, without violating any law of thermodynamics, or any physical law, through transformations repeated on always different volumes of fluid. The thermo- machine cannot function by exchanging air in closed environments and the work produced can become negative (i.e. the thermo-machine consumes energy) with certain configurations in the case where the atmospheric temperature drops below certain thresholds, in a similar manner to any heat pump currently in production. For the same volume of air processed (1 m³ of atmospheric air per second), with high atmospheric temperatures (such as summer ones of 30°C or 303°K) and lowering the compression ratios of the compressor 1 to 1:1.5 (152000 Pa), up to 60 KW of power (i.e. 60 kWh of work/energy every hour) can be obtained from the thermo- machine.

The heaters have not been taken into account in this analysis. By way of example, with an electromagnetic ray concentrator, such as a 3-metre diameter solar mirror, it is possible to superheat the last isochoric heating up to 550°C (823.15°K) before the last adiabatic expansion. In this way, it would be theoretically possible to produce a further 180 kWh energy every hour and increase the recovery of the Stirling engine to far higher values, considerably increasing the efficiency of the transformation of solar energy.

It is also possible to use the above-described thermo-machine for heating or cooling closed environments. In this utilization, even when the overall work produced by the thermo-machine is negative (i.e. when the electric energy absorbed by the compressor 1 is greater than the electric energy produced by the two turbines 4 and 7), there would still be a production of thermal deltas at very low cost, much lower than those currently available on the market. This is due to the fact that in all cases, energy recovery is still carried out, with the production of mechanical energy, even if lower than that necessary for repeating the transformations. It should be noted that utilization as a refrigeration system using air is neither polluting, nor hazardous.

According to a possible, but not limitative, embodiment, to start the turbomachine it is necessary bring the initially stationary turbines 4 and 7 into rotation by using, for example, a small reserve of compressed air or an electric starter motor.

According to a possible, but not limitative, embodiment, in order to further increase the amount of surplus energy, it is possible to use different superheating systems 12 mounted on the inlets of the turbines 4 and 7 (as in the examples in Figures 2-14), thereby increasing the volume of the compressed work fluid 2 and, in consequence, the thermal gradient that is transformed into useful work on the shafts of the turbines 4 and 7. In accordance with the statements made by Nikola Tesla, such a superheating system 12 in itself can have a coefficient of performance (COP - indicates the amount of work produced with respect to energy used) of one to tens of units, which means using a small percentage of the force extracted from the work fluid 2 can achieve a far greater supercharging effect on the system.

There can be one or more of these superheating systems 12, mounted in series or in parallel when more than one. Some superheating systems 12 can be fan-coils, the fans of which, if necessary, are driven by the shafts of the turbines 4 and 7, or heat exchangers designed to recover heat in existing industrial plants, such as, for example, from machinery coolants. With a very low work cost, the superheating systems 12 for superheating the inlet of the turbines 4 and 7 improve the efficiency of the turbomachine; however, the use of one or more superheating systems 12 is still optional and not obligatory. The potential superheating systems 12 are powered by the turbines 4 and 7, and they amplify the useful work.

One possible superheating system 12 (shown in Figures 2 and 3) envisages the construction of a heater 13, which is arranged upstream of the entrance of the work fluid 2 into turbine 4 or 7 and is composed of an inlet 14 and an outlet 15 between which a perforated structure, for example of iron, is placed to facilitate container-content heat exchange. This structure is superheated by a circuit containing an electromagnetic induction coil 16, possible two-wire. This electromagnetic induction coil 16 can have, for example, a damped-wave resonant electric power supply (using, for example, the circuit diagram shown in Figure 4), an alternating electric power supply (using, for example, the circuit diagram shown in Figure 5) , or a pulsed electric power supply (using, for example, the circuit diagram shown in Figure 6) ; according to one possible embodiment, the induction coil 16 could be powered through an electromagnetic or electrostatic generator driven by the corresponding turbine 4 or 7 (the generator can be on the shaft of the turbine 4 or 7 or mechanically connected to the turbine 4 or 7 by a transmission device) .

Another possible superheating system 12 (shown in Figure 7) is constituted by a dynamic decompressor 17 comprising a rotor 19 made of a conductive metal (copper, aluminium or similar) and a stator 18 provided with magnets 20 (which can be permanent magnets or electromagnets) , which generate powerful magnetic fields that affect the rotor 19; if the magnets 20 are permanent magnets, the polarities of the magnets 20 alternate (as shown in Figure 7), while if the magnets 20 are electromagnets, they are fed with alternating current. The rotation of the rotor 19 causes the generation of eddy currents on the former, which, by short-circuiting, superheat it to over 500°C. This heat will be transferred from the rotor 19 to the work fluid 2 in transit while the work fluid 2 laps against the rotor 19, causing an increase in temperature, and therefore in volume, of the work fluid 2; to increase the heat exchange surface of the rotor 19, the rotor 19 is preferably composed of a pack of mutually parallel discs set slightly apart from each other (in such a way that the work fluid 2 can flow between the discs of the rotor 19) . The coefficient of performance of this superheating system 12 is tied to the change frequency of the magnetic field and its intensity; this superheating system 12 in itself can have a coefficient of performance greater than 1:5.

A further possible superheating system 12 (shown in Figures 8- 11) is constituted by a heater 21 comprising discs 22 that each support a plurality of magnets 23 with alternating polarities, and a tube 24 made of a conductive metal (copper, aluminium or similar) that is arranged in a fixed position close to the discs 22. The discs 22 are, for example, brought into rotation by the turbine 4 or 7; following rotation of the discs 22, the tube 24 is subjected to a time-variable magnetic field that induces the generation of short-circuiting eddy currents, causing the heating of the tube 24 (and so the work fluid 2 that flows inside the tube 24 is heated, increasing its temperature and volume) . The heater 21 can have an axial shape as shown in Figures 8 and 9, or it can have a radial shape as shown in Figures 10 and 11. The heater 21 in itself can have a coefficient of performance greater than 1:5.

A further possible superheating system 12 (shown in Figure 12) comprises an electromagnetic ray concentrator 25, for example a solar one. The electromagnetic ray concentrator 25 could comprise at least one convex mirror 26 that directs (concentrates) solar rays onto a collector 27 that transfers the thus-reflected heat, in a known manner, to the work fluid 2 entering the turbine 4 or 7. This superheating system 12 uses solar energy, which is freely available at no cost.

A further possible superheating system 12 (shown in Figure 13) comprises a combustion chamber 28 fed with fossil fuels, coal, wood or anything else that produces combustion suitable for heating, and a heat exchanger 29 that is thermally coupled to the combustion chamber 28 and through which the work fluid 2 passes to enter the turbine 4 or 7. This superheating system 12 presumably has a coefficient of performance below 1:1, but can be of interest for recovering residual waste energy, such as from biomass gas, etc. A further possible superheating system 12 (shown in Figure 14) comprises a dynamic heater 30, in which a flow of compressed work fluid 2 enters a Venturi nozzle 31, expanding and then generating a vacuum inside a free rear outlet 32, to where more compressed work fluid 2 will be "sucked"; in consequence, the work fluid 2 obtained at the outlet of the nozzle 31 is at a lower pressure, but at a higher temperature. A Ranque-Hilsch vortex tube 33 is arranged at the outlet of the nozzle 31 and generates a cold low-pressure outflow and concentrates, at a second outlet, a hotter higher-pressure flow with respect to the inlet point. The pressure thus returns to that of entry, but the heat is increased, and consequently also the volume and flow of the work fluid 2. The coefficient of performance of this superheating system 12 is greater than 1 : 1 and depends on the sizing of the apparatus.

According to a possible embodiment, the larger flow of hot work fluid 2 in the superheating systems 12 can be transformed into higher pressure (transforming isobaric in isochoric) by means of an opportune diffusor nozzle, for example, a de Laval nozzle, suitable for converting the speed of the flow into static pressure.

According to a possible, but not limitative, embodiment, the turbomachine comprises a series of electronic flow controls to modulate the power produced by the turbomachine and to include and/or exclude some of the transformations depending on the purpose of the machine and its energy status during the transformations; for example, the electronic controls could act on the superheating systems 12, increasing or decreasing the efficiency, or could control a cut-off gate on the primary flow of the work fluid 2 to obtain the same effect, or could open and close bypass valves to exclude heat exchanges that, after having initiated the cycle, may have become inefficient.

According to an alternative and perfectly equivalent embodiment, heat concentrators can be used like the Ranque- Hilsch vortex tubes in order to favour and improve the efficiency levels of the various thermodynamic transformations . According to an alternative and perfectly equivalent embodiment, the turbines 4 and 7 could be replaced by another type of fluid dynamic machine that generates mechanical work by exploiting the expansion of the work fluid 2 (i.e. generates mechanical work by exploiting the overpressure of the work fluid 2) such as, for example, a piston engine with single or multiple expansion stages.

In the preferred, but not limitative, embodiment described above, two operator groups are envisaged, each composed of a superheating system 12, a turbine 4 or 7 and a decompression device 6 or 9 arranged between them in series and in this order. In general, N (where N is an integer equal to or greater than 1) cascaded operator groups are provided. From the third operator group onwards, always working on the same work fluid 2, they produce "more work" solely derivable from the multiplication effect of the coefficient of performance of the corresponding superheating systems 12.

In the preferred, but not limitative, embodiment described above, the work fluid 2 is constituted by atmospheric air; however, according to other embodiments, the work fluid 2 could be constituted by any other type of fluid (environmental medium) . The compressor 1 used in the above-described thermo-machine could be a "passive" compressor (i.e. without parts in cyclic movement) that, like the Neal valve, uses the thermal gradients to ensure that air compresses air. An innovative example of a "passive" compressor (usable in the above- described thermo-machine and also usable in other applications different from the above-described thermo-machine) is shown in Figure 16 and is based only on heat exchanges. The compressor 1 shown in Figure 16 comprises a main pipe 33 that extends from an inlet (where the air to compress enters) and an outlet (from which compressed air exits) . Along the main pipe 33, an air/air countercurrent heat exchanger 34 is arranged that exchanges heat between a cold fluid and the ambient temperature to cool air in isobaric conditions (i.e. at constant pressure) , causing a reduction in the volume of the air. Downstream of the heat exchanger 34, the main pipe 33 has a progressively decreasing section (i.e. it has a "funnel" shape); in other words, upstream of the heat exchanger 34, the section of the main pipe 33 has a first value, while downstream of the heat exchanger 34 the section of the main pipe 33 has a second value, smaller than the first value (the reduction in section takes place gradually thanks to a convergent "funnel" shape) . A non-return valve 35 is arranged along the main pipe 33 and downstream of the heat exchanger 34 (where the section of the main pipe 33 has already reached the second value) . A further heat exchanger 36, which heats, in isochoric conditions, the air to increase the pressure of the air, is arranged downstream of the non-return valve 35.

In use, air enters the main pipe 33 and, passing through heat exchanger 34, it cools (at constant pressure), decreasing its volume; after having passed through the non-return valve 35, the air passes through heat exchanger 35 where the air heats up (in isochoric conditions, i.e. at constant volume), increasing its pressure (not being able expand its volume as the space offered by the main pipe 33 is limited) .

One use of the compressor 1 shown in Figure 16 in the above- described thermo-machine is particularly advantageous and envisages inserting the heat exchanger 3 in front of the inlet of the compressor 1, which would thus be supercharged for free, given that a passive compressor such as that described compresses just by heat exchange and does not consume work.

The above-described thermo-machine has numerous advantages.

Firstly, the above-described thermo-machine enables producing mechanical work from the environmental medium through the extraction of heat, such as, for example, the heat in the atmosphere, in an effective and efficient manner.

Furthermore, the above-described thermo-machine is of relatively simple, economic and compact construction.

Finally, the above-described thermo-machine has an intrinsically solid mechanical structure that allows long uninterrupted periods of operation without any maintenance whatsoever .

Claims

C L A I M S

1) A thermo-machine that uses a work fluid in an open cycle; the thermo-machine comprising:

a compressor (1) to pressurize the work fluid (2) taken from the external environment by carrying out an isothermal compression;

a first heat exchanger (3; 3a) comprising a first circuit, which receives the work fluid (2) flowing out of the compressor (1), and a second circuit, which is fluidically insulated from and thermally coupled to the first circuit;

a first turbine (4), which receives the work fluid (2) flowing out of the first circuit of the first heat exchanger (3; 3a); and

a second turbine (7), which receives the work fluid (2) flowing out of the second circuit of the first heat exchanger (3; 3a);

wherein the work fluid (2) flowing out of the first turbine (4) flows through the second circuit of the first heat exchanger (3; 3a) so as to be heated by the work fluid (2) flowing out of the compressor (1); and

wherein the residual work fluid (10) flowing out of the second turbine (7) is released into the external environment at a temperature that is lower than the temperature of the work fluid (2) flowing into the compressor (1) .

2) A thermo-machine according to claim 1 and comprising a first decompression device (6), which is interposed between the first turbine (4) and the second circuit of the first heat exchanger (3; 3a) and allows the work fluid (2) to further release heat by expanding.

3) A thermo-machine according to claim 1 or 2, wherein the first turbine (4) and/or the second turbine (7) are replaced by another type of fluid-dynamic machine, which generates mechanical work by exploiting the expansion of the work fluid (2), such as, for example, a piston engine with one expansion stage or multiple expansion stages. 4) A thermo-machine according to claim 1, 2 or 3 and comprising a second decompression device (9), which is arranged downstream of the second turbine (7) and allows the work fluid (2) to further release heat by expanding. 5) A thermo-machine according to any one of claims 1 to 4 and comprising a recirculation pipe, which draws off a fraction of the residual work fluid (10) released into the external environment and feeds it between the compressor (1) and the first circuit of the first heat exchanger (3; 3a) through a non-return valve (11), which is arranged in the area of the outlet of the compressor (1) .

6) A thermo-machine according to any one of claims 1 to 5 and comprising a superheating system (12), which is fitted in the area of the inlet of at least one turbine (4, 7) and heats the work fluid (2) .

7) A thermo-machine according to claim 6, wherein the superheating system (12) is provided with a diffuser nozzle, for example a de Laval nozzle, which is designed to turn the speed of the flow into static pressure.

8) A thermo-machine according to claim 6 or 7, wherein the superheating system comprises a heater (13), which consists of an inlet (14) and an outlet (15) as well as, between them, a perforated structure, which is heated by a circuit containing an electromagnetic induction coil (16) supplied with a current that is variable in time.

9) A thermo-machine according to claim 6 or 7, wherein the superheating system (12) comprises a dynamic decompressor (17) provided with a rotor (19), which is made of a conductive metal and preferably consists of a pack of parallel discs slightly spaced apart from one another, and with a stator (18), which is provided with magnets (20) generating magnetic fields affecting the rotor (19) .

10) A thermo-machine according to claim 6 or 7, wherein the superheating system (12) comprises a heater (21) provided with discs (11), each supporting a plurality of magnets (23) with alternating polarity, and with a pipe (24) made of a conductive metal, which is arranged in a fixed position close to the discs ( 22 ) . 11) A thermo-machine according to claim 6 or 7, wherein the superheating system (12) comprises an electromagnetic ray concentrator (25) , for example for sunrays, preferably provided with at least one convex mirror (26), which directs the electromagnetic rays to a collector (27), which releases the heat reflected in this way to the work fluid (2) .

12) A thermo-machine according to claim 6 or 7, wherein the superheating system (12) comprises a combustion chamber (28) and a heat exchanger (29) , which is thermally coupled to the combustion chamber (28) and through which the work fluid (2) passes .

13) A thermo-machine according to claim 6 or 7, wherein the superheating system (12) comprises a dynamic heater (30) provided with a Venturi nozzle (31) and with a Ranque-Hilsch vortex tube (33), which is arranged in the area of the outlet of the nozzle (31) .

14) A thermo-machine according to any one of claims 1 to 13 and comprising an engine, which is designed to generate mechanical energy and is connected to the compressor (1) so as to operate the compressor (1), and, for each turbine (4, 7), at least one generator, which absorbs mechanical energy from the turbine (4, 7) .

15) A thermo-machine according to claim 14, wherein the engine is an electric motor and the generator is an electric generator producing the electric energy supplied to the motor.

16) A thermo-machine according to any one of claims 1 to 15 and comprising a second heat exchanger (3b) interposed between the first turbine (4) and the second circuit of the first heat exchanger (3; 3a) for heating the air that leaves the first turbine (4) by using the heat of the external environment.

17) A thermo-machine according to any of claims 1 to 16, wherein the compressor (1) is passive, that is without parts in cyclic movement, and comprises: a main pipe (33), which extends from an inlet, where the work fluid to be compressed enters, to an outlet, from which the compressed work fluid exits; a third heat exchanger (34), which cools the work fluid in isobaric conditions; a non-return valve (35) arranged downstream of the third heat exchanger (34); and a fourth heat exchanger (36), which heats, in isochoric conditions, the work fluid to increase the pressure of the work fluid; wherein downstream of the third heat exchanger (34) and upstream of the non-return valve (35), the main pipe (33) has a progressively decreasing section.

18) A passive compressor (1), that is without parts in cyclic movement; the compressor (1) comprising: a main pipe (33), which extends from an inlet, where the work fluid to be compressed enters, to an outlet, from which the compressed work fluid exits; a first heat exchanger (34), which cools the work fluid in isobaric conditions; a non-return valve (35) arranged downstream of the first heat exchanger (34); and a second heat exchanger (36), which heats, in isochoric conditions, the work fluid to increase the pressure of the work fluid; wherein downstream of the first heat exchanger (34) and upstream of the non-return valve (35), the main pipe (33) has a progressively decreasing section.