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DESCRIPTION

Technical field

The present invention relates to a thermochemical and thermodynamic cycle executable by a thermal machine, such as a reciprocating engine, a rotary engine or a gas turbine.

The present invention further relates to a specific and dedicated thermal machine, such as a reciprocating engine, a rotary engine or a gas turbine, configured for executing said cycle.

Background art

In the field of thermal machines, such as reciprocating or rotary internal combustion engines and gas turbines, it is known to utilize a number of thermodynamic transformations adapted to convert the heat generated by combustion of a fuel into mechanical energy, at the end of which transformations the system will return to its initial condition. Such transformations make up a so-called thermodynamic cycle of the direct type; this means that the cycle converts into mechanical energy the thermal energy of the heat generated by combustion.

In the automotive industry, for example, reciprocating internal combustion engines generally utilize the controlled-ignition Otto cycle (also referred to as Beau de Rochas cycle) , wherein combustion is triggered by a spark generated in the chamber, or the direct-ignition Diesel cycle, wherein combustion is triggered spontaneously in highly compressed air after fuel has been injected in stoichiometric ratio, in volumetric excess of oxidizer. Summary of the invention

It is one object of the present invention to provide a thermodynamic cycle and a thermal machine, such as a reciprocating engine, a rotary engine or a gas turbine, which can offer improved performance over the teachings of the prior art, particularly by attaining high energetic efficiency and exhaust gas emissions substantially purified from carbon dioxide.

In brief, the thermodynamic cycle and the thermal machine operate in a unique and specific manner, so that the intake, compression, carburetion and ignition steps are carried out with just one operation and at just one instant, as opposed to prior-art thermodynamic cycles and thermal machines, where such steps are divided, separate and distinct from one another.

According to the present invention, this and other objects are achieved through the subject matter defined in the appended independent claims.

It is understood that the appended claims are an integral part of the technical teachings provided in the present description of the invention.

Brief description of the drawings

Further features and advantages of the present invention will become apparent from the following detailed description, which is supplied by way of non-limiting example with reference to the annexed drawings, wherein:

Figure 1 is a schematic view of a thermodynamic cycle in accordance with an exemplificative embodiment of the present invention;

Figure la is a schematic view of an Otto thermodynamic cycle in accordance with the prior art; Figure 2 schematically shows a reciprocating internal combustion engine designed in accordance with an exemplificative embodiment of the present invention;

Figure 3 schematically shows a rotary engine designed in accordance with an exemplificative embodiment of the present invention; and

Figure 4 schematically shows a gas turbine designed in accordance with an exemplificative embodiment of the present invention.

Detailed description of the invention

Thermochemical and thermodynamic cycle and reciprocating engine

With reference to Figure 1, there is shown a thermodynamic cycle in accordance with an exemplificative embodiment of the present invention. For the sake of simplicity and brevity, said thermodynamic cycle will be illustrated herein in the ideal form (i.e. without taking into account any modifications due to properties and behaviours of real gases) , and represents an improved evolution of a per se known four- stroke Otto cycle or Diesel cycle.

With reference to Figures 2-4, there is shown a portion of a thermal propulsion machine structured in accordance with a first exemplificative embodiment of the present invention. In the first embodiment shown in the drawings, the thermal propulsion machine is a reciprocating internal combustion engine 10, in particular a two-stroke engine.

Reciprocating engine 10 comprises a tank 12 adapted to contain a propellant comprising a mixture of:

a hydrocarbon-based fuel, in particular said fuel being one of petrol, diesel oil or kerosene, an oxidizer, in particular treated liquid oxygen and/or high- olume hydrogen peroxide, said oxidizer being in stoichiometric proportion to said fuel,

water, in particular in a proportion of approximately 10% in weight of said fuel,

at least one chelating agent, in particular a chelating agent of Fe3+ of the first four generations, and at least one combustion enhancer.

Reciprocating engine 10 also comprises at least one hollow cylinder 14, and at least one piston 16 reciprocating in cylinder 14, thus defining a variable- volume chamber 18. Furthermore, reciprocating engine 10 includes at least one high-pressure, high-speed injector 20 situated in chamber 18 and adapted to inject a quantity of propellant, taken from said tank 12, into chamber 18. Reciprocating engine 10 is also equipped with at least one hot ignition point 22 at high temperature, situated in chamber 18 and adapted to produce an explosive combustion, through contact between the injected quantity of propellant and hot ignition point 22, when piston 16 reaches a position in the proximity of the top dead centre, without first compressing the injected quantity of propellant and without taking in air from the outside environment. Said combustion generates, starting from the injected quantity of propellant, an active fluid at high pressure containing carbon dioxide and water, and develops an explosion temperature comprised between approx. 1,700°C and approx. 3,200°C, which can dissociate the carbon dioxide contained in the active fluid in chamber 18 into a carbon fraction, particularly in substantially particulate matter form, and an oxygen fraction, particularly in substantially gaseous form, which are physically and chemically separate from each other.

Reciprocating engine 10 further comprises a main engine shaft 24, particularly in the form of a crankshaft, shaft 24 can be rotatably driven by the reciprocating motion of piston 16, in particular through a crank mechanism, piston 16 is adapted to move towards the bottom dead centre through the effect of the expansion of the active fluid in chamber 18.

Reciprocating engine 10 also includes at least one exhaust valve 26 situated in chamber 18 and adapted to be opened to expel the expanded active fluid from chamber 18 when the piston is in the proximity of the bottom dead centre. For example, exhaust valve 26 may comprise obstructing surfaces and seats made of heat-resistant materials, if necessary, such as stellite, tungsten, ceramics or the like. Preferably, the opening and closing of exhaust valve 26 are controlled by means of a synchronization device (not shown) appropriately adjusted in phase with crankshaft 16. For example, the synchronization device may be a per se known camshaft or hydraulic actuator (not shown) adapted to control the opening and closing of exhaust valves 26 in accordance with criteria per se known to those skilled in the art.

Furthermore, reciprocating engine 10 is equipped with diverting means 28 configured to divert the heavier carbon fraction contained in the active fluid expelled from the chamber from the lighter remaining part of the active fluid. Reciprocating engine 10 further comprises trapping means 30 configured to trap the diverted carbon fraction (e.g. a carbon scraper or pickup adapted to trap carbon inside of it, thus preventing it from being released) and exhaust means 32 configured to discharge into the outside environment a purified portion of the active fluid, free of the trapped carbon fraction and derived from the previously dissociated carbon dioxide. For example, exhaust means 32 may include an exhaust pipe like those typically employed in motor vehicles.

Diverting means 28 are adapted to convey the carbon fraction centrifugally , and comprise a deflecting impeller 28a, in particular shaped like a helicoid with conical or truncated-cone extension, having a plurality of axially- extending holes 28b or having suitably shaped blades pushing the heavier carbon particles radially outwards. Deflecting impeller 28a is adapted to be rotatably controlled by the active fluid being expelled from chamber 18.

Therefore, diverting means 28 act as a three-way turbine comprising a stator 28c, in which said deflecting impeller 28a is rotatably mounted about an axis of rotation. Stator 28c has an inlet 28d, in particular substantially axial, for the active fluid expelled from chamber 18, one or more substantially axial outlets 28e for the purified portion of the active fluid, and one or more substantially radial outlets 28f for the diverted carbon fraction .

In this manner, the carbon fraction is mostly directed radially, while the purified portion of the active fluid is mostly directed axially. Mechanical work is also developed, which is applied to the shaft of deflecting impeller 28a.

Reciprocating engine 10 further comprises a user device 34, which is situated downstream of the substantially axial outlet 28e of the three-way turbine, and which is adapted to receive the purified portion of said active fluid exiting stator 28c. User device 34 is prearranged for converting the residual energy of the purified portion of the active fluid into mechanical energy and/or electric energy. In particular, user device 34 includes an additional recovery turbine 34a with at least one stage, ending with a secondary engine shaft 34b, additional to main engine shaft 24. Preferably, secondary engine shaft 36 is arranged parallel to main engine shaft 24. In a particularly preferred manner, additional recovery turbine 34a can be designed to have its own rotor, which in this case coincides with secondary engine shaft 34b, rotatably cooperating (e.g. being coaxial to and possibly integral or unitary with) said deflecting impeller 28a, so that mechanical energy is transferred to secondary engine shaft 34b.

In short, main engine shaft 24 and secondary engine shaft 34b will constitute a pair of separate power output shafts, advantageously arranged in a parallel power output configuration .

Preferably, reciprocating engine 10 may comprise a control system configured to control the activation of injectors 20 in such a way as to inject propellant into chamber 18 when piston 16 is at an adjustable height from the top dead centre, which is determined on the basis of the operating conditions of the engine itself, thus defining a variable virtual compression ratio. This advantage is in particular due to the fact that, since the oxidizer intake phase and the subsequent compression of the fuel/oxidizer mixture have been eliminated, the instant at which the quantity of propellant mixture is injected and explodes can be determined with any desired volume of chamber 18.

Preferably, like typical automotive engines, reciprocating engine 10 may comprise a plurality of cylinders 14. According to a known configuration example, said cylinders 14 may be in a single or multiple number and may be arranged in line or in V configuration.

Cylinders 14 of the reciprocating engine are preferably provided on an engine block manufactured, for example, from cast aluminium or iron, and connected at the top to a cylinder head and at the bottom to an oil sump. For example, the inner surfaces of cylinders 14 may be made of cast iron, sintered material, cast iron or aluminium coated with a thick chrome layer or with ceramic, depending on specific requirements dictated by the operating temperatures involved. The engine block, the cylinder head and the oil sump are elements per se known to those skilled in the art and therefore, for the sake of brevity, they will not be described in more detail below.

Said reciprocating engine 10 may comprise optional elements to improve what is normally known and used in the automotive industry; for example, piston crown 16 may be equipped with a ceramic heat shield, if required by high temperatures that cannot be handled otherwise.

Preferably, hot ignition point 22 is a glow plug; for example, the glow plug can heat chamber 18 and reach a minimum temperature of approx. 800 °C, thus triggering a combustion in chamber 18 that dissociates carbon from carbon dioxide, which typically occurs between approx. 1,700°C and approx. 3,200°C.

With reference to Figure 1, the condition indicated by reference numeral 2 corresponds to an initial condition of the thermodynamic cycle, wherein piston 16 is in its minimum stroke position (or top dead centre) and the volume of chamber 18 is at its minimum value. Exhaust valve 26 is in its normal closed position.

In this phase, injector 20 injects into chamber 18 the above-mentioned quantity of propellant towards hot ignition point 22, which has been heated to an exemplificative temperature of 600°C - 800°C, or anyway such as to trigger the combustion of said quantity of propellant. As a result, the temperature and the pressure in chamber 18 increase significantly, because the closure of exhaust valve 26 prevents the burning propellant from exiting chamber 18. The engine thus reaches the cycle condition indicated by reference numeral 3.

The above-mentioned phase, i.e. the switching from condition 2 to condition 3, corresponds, in an ideal thermodynamic cycle, to an isometric transformation with heat abduction. For example, the instantaneous combustion temperature may reach values up to approx. 3,500°C, with corresponding consequences on the volume of the burned gases .

In the next phase, the quantity of propellant burning in chamber 18 exerts its pressure against piston 16, which then moves from the minimum stroke position towards the maximum stroke position (or bottom dead centre) , where the volume of chamber 14 is greatest. The engine thus achieves the cycle condition indicated by reference numeral 4.

The above-mentioned phase, i.e. the switching from condition 3 to condition 4, corresponds, in an ideal thermodynamic cycle, to an isentropic expansion transformation .

In the next phase, exhaust valve 26 opens and the burned gases produced by the combustion of said quantity of propellant are allowed to exit chamber 18. The engine thus achieves the cycle condition indicated by reference numeral 1.

The above-mentioned phase, i.e. the switching from condition 4 to condition 1, corresponds, in an ideal thermodynamic cycle, to an isometric transformation with heat subtraction. The exhaust gases that reach the exhaust manifold may have an exemplificative temperature up to approx. 900 °C.

In the next phase, piston 16 is pushed towards its minimum stroke position (or top dead centre) , while exhaust valve 26 stays open.

Therefore, the burned gases are expelled outside chamber 18 and are delivered to additional components of engine 10 arranged downstream of cylinders 14, in particular for capturing the separated carbon and advantageously recovering energy from the still hot gases substantially purified from carbon, which are then finally released into the outside environment .

When piston 16 reaches its minimum stroke position, exhaust valve 26 is brought again into the closed condition. Therefore, the engine is again in the cycle condition indicated by reference numeral 2, corresponding to the initial condition of the cycle.

It can be observed that, compared to an ideal traditional Otto cycle as shown in Figure la, there is no intake of air (line 5-1) from the outside of cylinder 14 and there is no compression of intake air (line 1-2) in chamber 18 before fuel is injected. In the exemplificative embodiment of the thermodynamic cycle according to the invention, the exhaust phase (line 1-2 in Figure 1, corresponding to line 1-5 in Figure la) does not include a subsequent intake phase (the line 5-1 of Figure la is absent in Figure 1) , and the phase of isometric transformation with heat abduction can be started immediately afterwards. In fact, the air intake and compression phases that precede fuel injection are "delegated" to the physical -chemical structure of the propellant.

It follows that a reciprocating internal combustion engine designed in accordance with the present invention implies numerous technical benefits and advantages.

For example, the absence of air intake and compression in chamber 18 of cylinder 14 allows to omit the whole air treatment apparatus, from the air filter to the intake valves. This simplifies the structure and mechanisms of the reciprocating internal combustion engine, while at the same time avoiding the dissipation of mechanical energy due to air intake and compression which occurs in engines and thermodynamic cycles designed in accordance with the prior art .

Furthermore, according to the present invention, it is possible to halve the number of cylinders of a reciprocating internal combustion engine while substantially preserving the same performance as prior-art engines, because the cycle of the present invention is substantially a two-stroke cycle, as opposed to a traditional four-stroke Otto cycle.

The reciprocating internal combustion engine and the associated thermodynamic cycle designed in accordance with the present invention are neither aspirated nor turbocharged engines, because no air is taken in and compressed, and the turbo effect can be replaced by adjusting the injected quantity of mixture.

The reciprocating internal combustion engine according to the invention can make easier and more effective the following additional applications:

electromagnetic braking with energy recovery, particularly effective in front -drive vehicles, and

four-wheel drive system with electric, as opposed to mechanical, transmission.

The higher instantaneous temperature of explosion, estimated in approx. 3,200°C, when compared to the approx. 2,000°C of the Otto cycle, can generate a dissociation of C0 ₂ into molecules of C and 0 ₂ , which can then be separated. The carbon fraction is delivered to trapping means 30 (e.g. thus transforming it into soot rather than ultra-thin powders) , and the purified portion is returned into the atmosphere via exhaust means 32.

As already described, the still hot exhaust gases purified from carbon (hence having a high reserve of energy) , can be used in an accurate energy recovery process by user device 34, e.g. a multistage turbine which can be coupled to a high-power electric generator (e.g. associated with secondary engine shaft 34b) , for the purpose of limiting the thermal pollution of the atmosphere and of using its energy in an electric motor coupled to the thermal engine in a hybrid solution.

Rotary engine

With reference to Figure 3, there is schematically shown a rotary engine 110 designed in accordance with a further exemplificative embodiment of the present invention .

Rotary engine 110 comprises a tank 12 adapted to contain a propellant comprising a mixture which is substantially identical to the one described above for reciprocating engine 10, a hollow stationary body 114, in particular toroidal in shape, and a rotor 116, which is coaxially rotatable about an axis of rotation in hollow stationary body 114, and which is fitted with a radial protrusion 116a, in particular a blade preferably having a circle involute profile.

Rotary engine 1110 also includes a shutter drum 117, which is rotatable in a synchronized manner against rotor 116, and which has at least one cavity 117a adapted to house protrusion 116a in a predetermined cycle-change angular position of protrusion 116a, every time rotor 116 completes one ^' revolution about its own axis; the inner walls of hollow stationary body 114, the outer walls of rotor 116 and the outer walls of said drum 117 delimiting a variable-volume rotary chamber 118. Said rotary engine 110 comprises a high-pressure, high-speed injector 20 adapted to inject a quantity of propellant, taken from tank 12, into the chamber 18.

Rotary engine 110 further comprises a hot ignition point 22 at high temperature, situated in stator 114 in an angular position immediately following the cycle-change angular position; hot ignition point 22 is adapted to produce an explosive combustion, through contact with the injected quantity of propellant, when protrusion 116a goes angularly past the cycle-change angular position, without first compressing the injected quantity of propellant and without taking in air from the outside environment. Said combustion generates, starting from the injected quantity of propellant, an active fluid at high pressure containing carbon dioxide and water, and develops an explosion temperature comprised between approx. 1,700°C and approx. 3,200°C, which can dissociate in chamber 118 the carbon dioxide contained in the active fliid into a carbon fraction, particularly in substantially particulate matter form, and an oxygen fraction, particularly in substantially gaseous form, which are physically and chemically separate from each other. Rotor 116 is rotatably controlled by the expansion of the active fluid in chamber 118, which exerts a thrust upon protrusion 116a.

Said rotary engine 110 includes an exhaust orifice 126 in stator 114, in an angular position immediately preceding said cycle-change angular position. The expanding active fluid can be expelled from chamber 118 through exhaust orifice 126 when protrusion 116a goes angularly past exhaust orifice 126.

Rotary engine 110 further comprises diverting means 28, trapping means 30 and exhaust means 32 designed in substantially the same way as described with reference to reciprocating engine 10.

Also rotary engine 110 comprises a user device 134, which is situated downstream of the substantially axial outlet 28e of the three-way turbine, and which is adapted to receive the purified portion of said active fluid exiting stator 28c. It is also prearranged for converting the residual energy of the purified portion of the active fluid into mechanical energy and/or electric energy.

Unlike reciprocating engine 110, user device 134 comprises at least one energy recovery stage 134a including a hollow stationary body for energy recovery 134b, in particular toroidal in shape, which is adapted to receive the purified portion of active fluid coming from the substantially axial outlet 28e of the three-way turbine. User device 134 also includes an energy recovery rotor 134c which is coaxially rotatable about an axis of rotation in the stationary body for energy recovery 134b, and which is fitted with a radial protrusion (not numbered) , in particular a blade preferably having a circle involute profile. There is also a shutter drum 134d, which cooperates with energy recovery rotor 134c to house the blade of the latter within a cavity (not numbered) obtained in said drum. In other words, the structure of the assembly made up of the hollow stationary body for energy recovery 134b and the energy recovery rotor 134c (inclusive of the radial protrusion) is substantially identical, from a structural and functional point of view, to that of hollow stationary body 114 and of rotatable rotor 116 fitted with radial protrusion 116a, except for the absence of injector 20 and of hot ignition point 22. No further combustion is actually triggered in said energy recovery apparatus 134; energy recovery rotor 134c is rotatably controlled through the effect of the residual energy of the purified portion of the active fluid.

In rotary engine 110, user device 134 has a plurality of recovery stages 134a, 134a' and 134a' ' , which are adapted to receive the purified portion of the active fluid coming from the substantially axial outlet, and to convert the residual energy of the purified active fluid into mechanical energy. Preferably, the first recovery stage 134a is designed as described above (i.e. it includes the hollow stationary body for energy recovery 134b and energy recovery rotor 134c) , and other recovery stages 134a' and 134a' ' are arranged in cascade and designed in substantially the same way as the first stage 134a.

Rotary engine 110 further comprises a control system similar to the one described for reciprocating engine 10, i.e. configured for controlling the activation of injector 20 in such a way as to inject propellant into chamber 18 when protrusion 116a is in an angular position that can be adjusted as a function of the operating conditions of rotary engine 110, thus defining a variable virtual compression ratio (similarly to reciprocating engine 10) . Gas turbine

With reference to Figure 4, there is schematically shown a gas turbine 210 designed in accordance with an exemplificative embodiment of the present invention. Gas turbine 210 comprises a tank 12 adapted to contain a propellant comprising a mixture of:

a hydrocarbon-based fuel, in particular said fuel being one of petrol, diesel oil or kerosene,

an oxidizer, in particular treated liquid oxygen and/or high-volume hydrogen peroxide, said oxidizer being in stoichiometric proportion to said fuel,

water, in particular in a proportion of approximately 10% in weight of said fuel; and

at least one chelating agent, in particular a chelating agent of Fe3+ of the first four generations, and at least one combustion enhancer.

Gas turbine 210 further comprises a hollow stator body 214, in particular defining a chamber 218 toroidal in shape or with multiple burners, and a service or auxiliary rotor 216, adjacent to chamber 218 and rotatable about an axis of rotation. Gas turbine 210 comprises a plurality of high- pressure, high-speed injectors 20, which are adapted to inject a quantity of propellant, taken from tank 12, into chamber 218. Gas turbine 210 also includes a corresponding plurality of hot ignition points 22 at high temperature, situated in said chamber and adapted to produce an explosive combustion, through contact between the injected quantity of propellant and hot ignition points 22, without first compressing said injected quantity of propellant and without taking in air from the outside environment.

The combustion generates, starting from the injected quantity of propellant, an active fluid at high pressure containing carbon dioxide and water, and develops an explosion temperature comprised between approx. 1,700°C and approx. 3,200°C, which can dissociate in chamber 218 the carbon dioxide contained in the active fluid into a carbon fraction, particularly in substantially particulate matter form, and an oxygen fraction, particularly in substantially gaseous form, which are physically and chemically separate from each other.

Rotor 216 is rotatably controlled by the expansion of the active fluid in chamber 218, and has a special profile, obtained in particular through suitable blades, that diverts the heavier carbon fraction, contained in the active fluid expelled from the chamber, from the lighter remaining part of the active fluid.

Gas turbine 210 further comprises trapping means 30 (situated at the external radial periphery of the stator 214, facing towards the service or auxiliary rotor 216) and exhaust means 32, both substantially designed as described with reference to reciprocating engine 10 and rotary engine 110. Unlike reciprocating engine 10 and rotary engine 110, in this case diverting means 28 are absent, in that their function is directly carried out by service or auxiliary rotor 216, which, being equipped with appropriately designed centrifugal blades (or possibly with helicoid blades, as described for deflecting impeller 28a) , is per se able to convey the heavy particles radially towards the outside hollow stator body 214.

Gas turbine 210 further comprises a plurality of reaction nozzles 234 situated downstream of said service or auxiliary rotor. As an alternative to or in combination with the reaction nozzles, particularly whenever the gas turbine is not only intended for propulsion/aeration purposes, it is also conceivable to employ an additional power rotor (not numbered) rotatable about an axis of rotation and situated downstream of service rotor 216.

Hollow stator body 214 has a substantially axial outlet (not numbered) for the purified portion of the active fluid, which opens into exhaust means 32, and a substantially radial outlet (not numbered) for said diverted carbon fraction, which opens into said trapping means 30.

Therefore, service rotor 216 is configured to output mechanical work, in particular intended for driving auxiliary accessories of gas turbine 210, while the remaining energy of the purified portion of the active fluid can be supplied to the power rotor, which is adapted to output mechanical work, or to reaction nozzles 234, which are adapted to produce reaction propulsion or thrust.

In this case as well, gas turbine 210 includes a control system (not shown) , which is configured to control the activation of injectors 20 in such a way as to inject propellant in a manner adjusted as a function of the pressures developing in chamber 218 and of the operating requirements of the turbine itself, thus defining a variable virtual compression ratio.

Finally, gas turbine 210 further comprises a cooling system 238, in particular of the turbo-fan and/or turbo- water type, configured to generate overheated air and/or steam capable of exerting a propulsive thrust in addition to that produced by the expanding active fluid.

In this embodiment, cooling system .238 is of the turbo-fan type, i.e. it includes a fan 238a situated upstream of chamber 218 and adapted to convey air axially from the outside through an annular sleeve 238b, which is radially external to chamber 218. Annular sleeve 238b ends downstream of chamber 218, substantially immediately upstream of service rotor 216, i.e. in a position axially past the region where injectors 20 output the propellant mixture at high pressure and high speed towards hot ignition points 22 and where the explosive combustion then takes place. In other words, the air flow (the temperature of which is significantly lower than that of the expanding active fluid) is made to join the active fluid only after the explosive combustion has taken place in chamber 218, which combustion occurs, in this embodiment as well, without taking in or feeding external air.

Of course, without prejudice to the principle of the invention, the forms of embodiment and the implementation details may be extensively varied from those described and illustrated herein by way of non-limiting example, without however departing from the scope of the invention as set out in the appended claims.

Barzano & Zanardo Milano S.p.A.

/GV