Thermoelectric plant with super-criticality phase fluid

Abstract

System (1) for producing work, heating and / or cooling, comprising a heat engine (2) for producing mechanical work, having a plurality of gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c) provided with teeth (D), defining working chambers (20) for expanding a fluid, and arranged to mesh with each other, a generator or alternator (15), connected to the gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c) of the heat engine (2) by means of at least one mechanical shaft, for converting into electric current the mechanical work of rotation of the gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c) induced by the direct thrust of the fluid on the teeth (D), a heat exchanger (3, 4), connected via a conduit to the heat engine (2), to cool and / or heat the fluid, a pump (5) having a plurality of compression stages for compressing the fluid and connected via a conduit to the heat exchanger (3, 4) and via a further conduit to the heat engine (2), a motor (14) to drive the pump (5); the system (1) being characterized in that the teeth (D) of the gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c) of the heat engine (2) are provided with dynamic gas seals (21) between the working chambers (20) to keep the fluid, which is in supercritical conditions, confined in a single working chamber (20) while it expands between the teeth (D) that form said working chamber (20); and the stages of the pump (5) are provided with dynamic gas seals (5b) between one stage and the other to keep the fluid, which is in supercritical conditions, confined to a single stage while it is compressed.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a system and a method for producing work, heating and / or cooling with fluid in supercritical phase. The system is configured to produce an amount of entropy preferably no greater than that produced on Earth by solar radiation, for a given temperature, and simultaneously have a very high efficiency, for example greater than 80%.STATE OF THE ART

[0002] Industrial systems, for example in the steel, cement or chemical industries, as well as electric power plants, produce a large amount of waste heat in their production processes, which exacerbates global warming. The production of this high amount of waste heat is due to the fact that the production processes rely on thermodynamic cycles with irreversible transformations, which generate a high amount of entropy. Some examples of the most commonly used thermodynamic cycles are the cascade Rankine cycle (CRC), the organic Rankine cycle (ORC), the Kalina cycle and the combined cycle, comprising a Brayton-Joule cycle and a Rankine cycle. The amount of entropy produced depends not only on the type of transformations in the thermodynamic cycle, but also on the cycle efficiency. The greater the efficiency is, the less amount of dissipated energy will be produced in the form of waste heat.

[0003] The problem with producing a high amount of waste heat is that this heat, if not recovered, will be released into the environment by radiation, for example through surfaces, chimneys and the exhaust of buildings in which the thermodynamic processes take place, thereby causing a permanent increase in the temperature of the environment.

[0004] The increase in entropy, corresponding to waste heat, caused by the natural process of solar irradiation, can be obtained from the following formula: Δs = 1 − r ⋅ Q ⋅ 1 T o − 1 T , where Q: thermal energy the Earth receives from the Sun; T 0 : temperature of the earth's surface, which is on average equal to 288 K; T: temperature of the surface that emits the thermal energy, i.e. the solar photosphere at 5800 K; r: efficiency representing the part of thermal energy emitted by the emitting surface but not absorbed by the Earth. Due to the increase in entropy on Earth due to solar irradiation, r equals 0.34 and represents the part of solar energy which, after various interactions with the atmosphere and the terrestrial surface, is reflected by the Earth and thus sent back into space.

[0005] The increase in entropy caused by industrial processes, by contrast, can be calculated according to the following formula: Δs = PED T o ⋅ 1 − ζ , where PED: primary energy demand, obtained by multiplying the final energy demand by the primary energy factor of the energy source used, which takes account of the amount of energy necessary to extract, convert and transport the energy source to the building where the industrial process takes place; T 0 : ambient temperature; ζ: process efficiency.

[0006] The increase in the entropy of the environment, in the form of the release of waste heat, influences the parameter of entropic load in a directly proportional manner. The concept of entropic load represents the yearly temperature increase tied to climate change in the atmospheric layer above a certain emitting area. For an area A, this value is calculated with the following formula: t Atm = Δ s ⋅ T a ρ ⋅ A ⋅ H ⋅ c P where T a is the ambient temperature, Δs is the increase in entropy produced, ρ is the specific weight of the air at sea level at an ambient temperature of 20°C, approximately 1.2 kg / m 3< , A is the area emitting thermal energy, H is the thickness of the atmospheric layer, approximately 20 km, and c P is the specific heat of the air at a constant pressure of approximately 1.005 kJ / kg·K.

[0007] One disadvantage of conventional systems, such as, for example, coal-fired power plants, photovoltaic power plants, combined-cycle power plants, cogeneration plants, etc., is that one has Δs > Δs of the natural process and thus t Atm > t Atm of the natural process. In other words, the increase in entropy and increase in temperature produced by such plants are greater than those produced by the natural process.

[0008] A hybrid thermoelectric system is known from patent application DE 10 2017 002 286 A1, filed by the inventors prior to the present invention. One disadvantage of the system disclosed in this patent application is that the fluid, called working fluid, never reaches supercritical conditions. This means that the efficiency and amount of work produced are lower. Furthermore, it is necessary to reach higher temperatures compared to the system of the present invention, with a consequent increase in the risk of producing environmental thermal pollution.SUMMARY OF THE INVENTION

[0009] The object of the present invention is to enable the production of work, heating and / or cooling without causing an increase in entropy and in the thermal load above the values naturally produced by solar irradiation and ensuring, at the same time, a very high efficiency, for example greater than 80%.

[0010] This object is achieved by a system according to claim 1 and a method according to claim 9. Preferred embodiments are defined in the dependent claims.

[0011] A system for producing work, heating and / or cooling according to the present invention comprises a heat engine for producing mechanical work, having a plurality of gears provided with teeth, defining working chambers for expanding a fluid. The gears are arranged so as to mesh with each other. The system further comprises a generator or alternator, connected to the gears of the heat engine by means of at least one mechanical shaft, for converting into electric current the mechanical work of rotation of the gears induced by the direct thrust of the fluid on the teeth. In addition, the system comprises a heat exchanger, connected via a conduit to the heat engine, to cool and / or heat the fluid, and comprises a pump having a plurality of compression stages for compressing the fluid and connected via a conduit to the heat exchanger and via a further conduit to the heat engine. Each connection via a conduit can be direct or indirect, and can thus comprise a single conduit, or also several conduits and other interposed functional elements, for example valves. In addition to this, the system comprises a motor for driving the pump. The system is characterized in that the teeth of the gears of the heat engine are provided with dynamic gas seals between the working chambers to keep the fluid, which is in supercritical conditions, confined in a single working chamber while it expands between the teeth that form said working chamber. Moreover, the stages of the pump are provided with dynamic gas seals between one stage and the other to keep the fluid, which is in supercritical conditions, confined to a single stage while it is compressed.

[0012] An advantage of this system is that work, useful heat and air conditioning can be produced simultaneously. Furthermore, the waste heat is recovered through the heat exchanger, pump and heat engine. Therefore, the amount of entropy produced is substantially less than or equal to, net of losses, that of the natural process. Therefore, the system does not cause warming.

[0013] One of the advantages of using a heat engine and gears to produce work and thus electricity is that it is very compact and has high efficiency.

[0014] A further advantage of this system is that the dynamic gas seals of the engine and pump allow for processing a fluid in a supercritical phase and increasing the pressure produced in the pump.

[0015] A further advantage of this system is that, by processing a fluid in a supercritical phase, it is possible to bring about an isothermal expansion of the fluid in the heat engine, which enables a large amount of work to be obtained.

[0016] In a preferred embodiment, the system further comprises a separator, connected via a conduit to the heat engine and via a further conduit to the pump, for the separation of the fluid into two distinct fluid parts, in the event that the fluid is a mixture, preferably of carbon dioxide and water containing additives.

[0017] An advantage of having a separator is that the system can work with a fluid that is a mixture of two different fluids. In fact, the two fluids can be selected so as to have physicochemical characteristics which improve different aspects of the system's performance. A first fluid can be, for example, carbon dioxide, which has the advantage of reaching supercritical conditions at relatively low temperatures (304 K to 7.38 MPa = 73.8 bar). A second fluid can be, for example, water, which advantageously has a very high specific heat (c p = 4186 J / kg·K). The first fluid, for example carbon dioxide, reaches supercritical conditions inside the pump and is subsequently isothermally expanded in the heat engine. It is called working fluid, because it enables most of the mechanical work to be performed and, preferably, it can go into a supercritical phase at temperatures no greater than 375 °C. The second fluid, for example water comprising preferably at least one of graphite, glycerin, antioxidants, anticorrosives, and antifoaming agents, is called heating fluid or heat carrier. In fact, it can be heated separately in the heat exchanger and be introduced hot into the pump and / or heat engine to be mixed with the working fluid and thus transmit heat to it by direct contact. The mixture of working fluid and heating fluid can preferably contain from 8% to 25% of working fluid. Furthermore, the mixture of working fluid and heating fluid can preferably have a dynamic viscosity of 10 Pa·s at about 80 °C. The fluid or mixture used in the system according to the invention are preferably in a temperature range between 30°C and 375°C and / or in a pressure range between 50 bar and 280 bar.

[0018] By this means, one obtains the advantage that the working fluid directly obtains heat via the heating fluid and thus the isobaric expansion starts from an initial stage at a higher temperature and consequently a larger amount of work is produced.

[0019] In a preferred embodiment, the gears of the heat engine have grooves on the surface between one tooth and the other for the capture of liquids.

[0020] One advantage of this is that the liquids, preferably the heating fluid, are captured within the grooves so that, even if they are at high pressures and temperatures, they do not cause damage by impacting on the gears in movement.

[0021] In a preferred embodiment, the system further comprises a circuit of a consumer connected to the heat exchanger to provide cooling and / or heating to the consumer.

[0022] One advantage of this is that heating and / or cooling can be supplied to a consumer and that heat is recovered, which could otherwise become waste heat and thus thermally pollute the environment.

[0023] In a preferred embodiment, the system further comprises a heat pump located on a conduit between the heat exchanger and the heat engine to compress at least a part of the fluid before that part enters the heat engine.

[0024] An advantage of using the heat pump is that the temperature and pressure of the working fluid are further increased. Therefore, the work produced through the isothermal expansion inside of the heat engine increases, as does the capacity of the working fluid to exchange heat. Consequently, the overall efficiency of the system increases.

[0025] In a preferred embodiment, the heat exchanger comprises a liquid collection sump to collect at least a part of the fluid while that part condenses, before the fluid is sent to the pump through a conduit or to the heat pump through an additional conduit.

[0026] An advantage of using a liquid collection sump is that the fluid, for example the working fluid and / or the mixture of working fluid and heating fluid can be made to condense therein. In this way, lower minimum cycle temperatures are reached, and more work is produced.

[0027] In a preferred embodiment, the system further comprises a solar system connected to an additional heat exchanger to supply heat to at least a part of the fluid before that part enters the heat engine and / or pump.

[0028] An advantage of using a solar system to further heat the fluid is that the efficiency of the pump and / or heat engine is increased. Therefore, the work produced is also increased. Furthermore, by increasing the temperature of the fluid, its capacity to provide heat to a consumer is increased.

[0029] In a preferred embodiment, the system further comprises a burner connected to a heat exchanger to provide heat to at least a part of the fluid before that part enters the heat engine and / or pump.

[0030] An advantage of this is that the fluid is further heated and thus the efficiency of the pump and / or heat engine is increased. Consequently, the work produced is increased and the capacity of the fluid to provide heat to a consumer is increased.

[0031] Having a burner that uses, for example, biomass, as an alternative or in addition to a solar system, will allow for a continuous use of a heat source and, in the event of a combination with a solar system, allow the heat sources to be differentiated so as to be able to continue heating the fluid if one of the two sources is no longer available.

[0032] A method, according to the present invention, for producing work, heating and / or cooling using a fluid, is characterized by an isothermal expansion of the fluid, preferably carbon dioxide, which is in a supercritical phase, an isobaric cooling of the fluid and an isochoric compression of the fluid.

[0033] An advantage of the sequence of transformations defined in said method is that a large amount of work is produced while the waste heat is recovered and cooling or heating can simultaneously be delivered to a consumer. Furthermore, the entropy produced in the process substantially does not exceed the amount of entropy produced through the natural process of solar irradiation of the Earth.

[0034] In one embodiment, an isentropic expansion is achieved between the isothermal expansion and the isobaric cooling.

[0035] An advantage of this isentropic expansion taking place after the isothermal expansion is that the work produced by the heat engine is further increased.

[0036] In one embodiment, isothermal cooling is achieved between the isobaric cooling and the isochoric compression.

[0037] One of the advantages of this isothermal cooling taking place is that the volume of the fluid is further decreased before the isochoric compression and thus the work produced by the system increases.

[0038] In one embodiment, the method is characterized in that the isothermal expansion takes place in a heat engine, the isobaric cooling takes place in a heat exchanger and the isochoric compression takes place in a pump.

[0039] An advantage of this is that work, heating and / or cooling can be produced efficiently and with a reduced number of components.

[0040] In a preferred embodiment, the fluid is a first fluid used as a working fluid, and characterized by the introduction, in addition to the first fluid, of a second fluid as a heating fluid, preferably water comprising at least one of graphite, glycerin, antioxidants, anticorrosives, and antifoaming agents, during the isothermal expansion in the heat engine and / or during the isochoric compression in the pump.

[0041] An advantage of adding a second or additional fluid, said heating fluid, to the first fluid, said working fluid, is the possibility of selecting the two fluids so as to have physicochemical characteristics which improve different aspects of the method's performance. As mentioned, the first of the two fluids can be, for example, carbon dioxide, which has the advantage of reaching supercritical conditions at relatively low temperatures (304 K at 7.38 MPa = 73.8 bar). The second fluid can be, for example, water, which advantageously has a very high specific heat (c p = 4186 J / kg·K). Therefore, the working fluid can directly obtain heat via the heating fluid and thus the isothermal expansion starts from an initial state at a higher temperature and, consequently, a larger amount of work is produced.

[0042] Furthermore, if the heating fluid is water comprising graphite, the water will act as a means of transport for the graphite. Graphite increases the thermal conductivity of the walls of the system on which it deposits and thus favors heat exchanges, for example in heat exchangers. Furthermore, the graphite increases lubrication, thereby reducing friction in the system components. In addition, the combination of water and graphite, preferably graphite powder, forms a viscous heating fluid. This viscosity can be further increased using glycerin and makes it possible to increase the impermeability of the dynamic gas seals. Antioxidant and anticorrosive agents have the effect, respectively, of reducing oxidation and the corrosion of the walls of the system. Antifoaming agents prevent the formation of foam and thus increase the efficiency of the pump, the heat engine and consequently the system.BRIEF DESCRIPTION OF THE FIGURES

[0043] Additional features and advantages will become more apparent from the following description of embodiments of the invention with reference to the appended drawings. From these drawings it may be seen that: Fig. 1 represents a diagram of a system according to one embodiment of the present invention. Fig. 2a represents a section of a detail of a heat engine with concentric gears having teeth provided with dynamic gas seals, according to one embodiment of the invention. Fig. 2b represents a variant of the heat engine shown in Fig. 2a, in which the gears have grooves on the surface between one tooth and the other for the capture of liquids, according to another embodiment of the invention. Fig. 3 schematically represents a heat engine with eccentric gears having dynamic gas seals and blades to increase the volume of the working chambers, according to another embodiment of the invention. Fig. 4 (cross section detail) schematically represents a heat engine in which the gears are separated by a separator for the uniform redistribution of fluid between them, according to a further embodiment of the invention. Fig. 5a (cross section) and Fig. 5b (section obtained by cutting along the line A-A in Fig. 5a) schematically represent a variant of the heat engine in which the gears have double helical teeth. Fig. 6a (cross section) and Fig. 6b (section obtained by cutting along the line A-A in Fig. 6a) schematically represent a variant of the heat engine with three shafts and corresponding gear wheels. Fig. 7 schematically represents a variant of the heat engine with a hermetic seal. Fig. 8 schematically represents a variant of the heat engine, which is double and has straight teeth and a hermetic seal. Fig. 9 schematically represents a variant of the heat engine, which is double and has double helical teeth and a hermetic seal. Figs. 10a and 10b respectively represent a diagram p,V and a diagram T,S of a thermodynamic cycle achievable by a system according to one embodiment of the present invention, on the working fluid in winter. Figs. 11a and 11b respectively represent a diagram p,V and a diagram T,S of a thermodynamic cycle achievable by a system according to one embodiment of the present invention, on the working fluid in summer. Fig. 12 represents a diagram T,S of a thermodynamic cycle achievable by a system according to another embodiment of the present invention and a thermodynamic cycle achievable by a heat pump comprised in said system. Fig. 13 represents a diagram T,S of a variant of a thermodynamic cycle achievable by a system according to another embodiment of the present invention and a thermodynamic cycle achievable by the heat pump. Fig. 14 represents a diagram p,S of an example of the temperature conditions and entropy to which the working fluid (in this example carbon dioxide) is brought by a thermodynamic cycle carried out by a system according to the present invention compared to working fluids subjected to the organic Rankine cycles used in conventional energy production systems. Fig. 15 represents a diagram T,S showing the temperature range and entropy to which the working fluid is brought by a system according to the present invention compared to conventional processes. Fig. 16 schematically represents the thermodynamic cycles achievable by a system according to the present invention having a double heat engine. Fig. 17 graphically represents the trend in thermal and electric power and the torque produced by the heat engine upon the increase in relation to the number of revolutions, according to the present invention. DETAILED DESCRIPTION

[0044] Identical reference signs listed in different figures designate identical, corresponding or functionally similar elements. It is evident to the person skilled in the art that the individual features described in different embodiments can also be implemented in a single embodiment, provided that they are not structurally incompatible. Similarly, the various features described in the context of a single embodiment can also be provided in a number of embodiments, individually or in any suitable sub-combination.

[0045] Fig. 1 shows a first embodiment of a system 1 for producing work, heating and / or cooling according to the present invention. The operating modes of the system 1 are described below making reference to the components shown in Fig. 1.

[0046] The system 1 comprises, as essential elements, a heat engine 2 connected via a conduit to a heat exchanger 3 or 4. The heat exchanger 3 or 4 is in turn connected via a conduit to a pump 5. The pump 5 is connected via a further conduit to the heat engine 2. The fluid (working fluid or mixture of working fluid and heating fluid) enters the heat engine 2 in supercritical conditions, exerting a direct thrust on the teeth D of the gears 18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c of the engine, thus setting them into rotation and producing mechanical work. The rotation of said gears causes an isothermal expansion of the working fluid or mixture. Subsequently, the working fluid or the mixture exits the heat engine 2 and enters, via the conduit, into the exchanger 3 or 4, in which it transfers heat, thus undergoing an isobaric cooling. Then the working fluid or mixture exits the exchanger 3 or 4 and enters the pump 5 via the other conduit. In the pump, the working fluid or mixture undergoes an isochoric compression which increases the pressure and temperature thereof until reaching supercritical conditions. Upon exiting the pump, the working fluid or mixture enters the heat engine 2 via the further conduit and the cycle starts again.Operating mode of the exchangers 3 and 4Winter operation:

[0047] In said system 1, the heat engine 2 is filled, preferably isobarically, with working fluid and heating fluid. The working fluid is in supercritical conditions and, in the example described here, is carbon dioxide. The heating fluid in this example is water comprising at least one of graphite, glycerin, antioxidants, anticorrosives, and antifoaming agents.

[0048] Inside the heat engine 2, the fluid exerts pressure on the gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c in Fig. 2-6) of the heat engine, setting them in motion, and undergoes an isothermal expansion. Further information on the operation of the heat engine 2 is contained below in the paragraph "Structure and operation of the heat engine 2". Consequently, mechanical work is performed, which is then transformed into electric current in the generator or alternator 15. The generator can be for example an alternating current generator with permanent magnets.

[0049] From the heat engine 2, the expanded mixture of working fluid and heating fluid is guided into the separator 6, preferably a drip separator, via the conduits c1, c2 and the valve v1. In said separator, the working fluid and heating fluid are separated from each other.

[0050] Then the working fluid is guided into the heat exchanger 3 via the conduit c3. In said heat exchanger there is the hot water circuit CO-ac of the consumer CO. The consumer CO represents for example a consumer of a home or a shopping center or factory that needs heat to heat interiors in winter. Inside the heat exchanger 3, the working fluid transfers heat to the hot water circuit CO-ac. This transfer of heat takes place according to an isobaric transformation and with an initial temperature difference of about 25 °C between the hot working fluid and the water to be heated. Subsequently, the working fluid, still hot, passes through the conduit c4 and the valve v2, preferably an expansion valve, until arriving in the heat exchanger 4. In said heat exchanger the working fluid is further cooled according to an isobaric transformation and transfers additional heat to the circuit of the consumer CO. Subsequently, the working fluid is guided through the conduit c5 on the suction side of the pump 5.

[0051] Alternatively, based on the amount of heat that the working fluid must exchange with the hot water circuit of the consumer CO, the heat exchanger 4 can be bypassed. In order to bypass said heat exchanger, the working fluid in the conduit c4, by means of the valve v3, is diverted into the conduit c5 and enters directly into the pump 5.

[0052] The path of the heating fluid after it has been separated in the separator 6 will now be considered. At the outlet of said separator, the heating fluid is hot. It is for example at a temperature of 100°C. From the outlet of said separator, the heating fluid is guided through the conduit c6 and the valve v5 into the second pressure stage of the pump 5.

[0053] In said pump, the thermal energy of the hot heating fluid is recovered as a result of the mixing of the working fluid and heating fluid and the isochoric pressure increase. In particular, about 159 kJ / kg of thermal energy on average, for example, can be regained from the heating fluid.

[0054] Alternatively, it is possible to bypass the separator 6. In this case, the mixture of working fluid and heating fluid exiting the heat engine 2 can be guided directly into the heat exchanger 3 through the conduit c2, the valve v1, the conduit c7, the valve v4 and the conduit c3. Inside the heat exchanger 3, the mixture of working fluid and heating fluid transfers heat to the water of the circuit CO-ac. In this manner, on cold days, a larger amount of thermal energy can be provided to the consumer. For example, the heat transferred to the water circulating in CO-ac can be about 80 kJ / kg of thermal energy in order to obtain an increase of about 40°C in the temperature of that water.

[0055] In light of what was illustrated previously, in the present invention, the process heat can be recovered in the working fluid mixed with the heating fluid in the pump 5 or it can be used as useful heat through the heat exchangers 3 and / or 4. Therefore, no waste heat is dispersed into the environment and, consequently, no thermal pollution is caused.Summer operation:

[0056] In summer, the filling and isothermal expansion of the mixture of working fluid and heating fluid take place in a manner similar to the one previously described for winter.

[0057] Upon exiting the heat engine 2, the mixture is brought into the separator 6 as previously described for winter operation. In said separator, the working fluid and heating fluid are separated from each other.

[0058] In summer operation, the heat exchanger 3 is bypassed, for example by closing a valve (not represented in Fig. 1) placed on the conduit c3 immediately before the heat exchanger 3. Therefore, upon exiting the separator 6, the working fluid enters the conduit c3, is diverted into the conduit c8, passes through the valve v4 and continues until arriving at the conduit c4. After that, via the valve v2, it enters the heat exchanger 4. In particular, the valve v2 preferably brings about an isenthalpic throttling which is regulated based on the temperature of the working fluid necessary in the heat exchanger 4 to exchange with the circuit of the consumer the amount of heat demanded by that consumer.

[0059] In summer, the consumer CO demands cooling from their air conditioning system through the cold water circuit CO-af. The water of said circuit is cooled by the working fluid inside the heat exchanger 4. If no cooling is demanded by the consumer CO, the heat exchanger 4 is bypassed by the working fluid. In fact, the working fluid is diverted from the conduit c4 through the valve v3 into the conduit c5 and brought into the suction side of the pump 5.

[0060] The heating fluid will now be considered. As in winter, after having been separated from the working fluid in the separator 6, it passes through the second conduit c6 and the valve v5 until arriving in the pump 5. Inside the pump, the heating fluid is mixed with the working fluid and undergoes an isochoric compression.Operating mode of the pump 5 in summer and in winter

[0061] The heating fluid and working fluid are mixed and compressed isochorically inside the stages of the pump 5. In said pump, pressure and heat are imparted to the mixture, so as to bring the working fluid into supercritical conditions. The pump 5 is described in detail below.

[0062] The pump 5 can be for example a screw pump, a gear pump, a constant-pressure pump or a worm pump, like in the example illustrated in Fig. 1. One or more working chambers 5a may be present, of equal size with a dynamic seal 5b relative to the longitudinally elongate housing 5c. The pump 5 compresses the mixture of working fluid and heating fluid inside the working chamber 5a according to the Archimedes' screw principle.

[0063] The pressure that can be reached by compression is defined by the number of working chambers 5a and the volumetric flow rate (m 3< / s) can be flexibly adapted according to the seasons of the year by controlling the number of revolutions of the pump driven by the electric motor 14. The isochoric compression of the mixture, which is set in motion by the screw, is very advantageous from an energy standpoint, since thermal energy Q is recovered through this compression according to the following equation: Q = m ⋅ cv ⋅ Δt where m is the mass of the mixture set in motion, cv is the specific heat at a constant volume, and Δt is the change in temperature of the mixture.

[0064] The longitudinally elongate housing 5c of the pump 5 can contain from 4 to 28 pressure stages with, for example, a uniform thread pitch and hence constant size of the working chambers 5a. If a pressure increase of about 10 bar is obtained per stage, depending on the number of stages, a pressure change of 40 bar to 280 bar can be achieved in the mixture of working fluid and heating fluid. The thread pitch of the support elements 5e is determined based on the final pressure to be obtained. In the last two pressure stages, the thread pitch is preferably made steeper in order to increase the final pressure per revolution.

[0065] The wall of the longitudinally elongate housing 5c is smooth, whereas cavities, for example hexagonal, honeycomb-like ones 5d, can be created on the working cylinder on which the support elements 5e are mounted to increase the contact surface and thus favour the cooling or heating of the working fluid and heating fluid.

[0066] One of the features differentiating the pump 5 from the pumps of the prior art are the dynamic gas seals 5b, situated, for example, on the upper part of the thread so as to come into gastight contact with the inner wall of the housing 5c of the pump 5. The dynamic gas seals 5b are movable and work between the smooth wall of the housing 5c and the pump 5. The lip of a seal 5b is pushed by the working pressure in the pump 5 against the smooth inner wall of the housing 5c. Simultaneously with this, the force of expansion of the fluid or mixture contributes to the gastightness of the dynamic seal. The seal 5b can be inserted into a slot cut into the support elements 5e.

[0067] One of the technical effects of these seals is that they make it possible to reach high pressures also with fluid in a supercritical phase and consequently having low viscosity. The pressure is increased gradually from one stage of the pump 5 to another so as not to apply excessive stress on the seals 5b. The seals 5b can preferably be made of polytetrafluoroethylene (PTFE), i.e. Teflon ®< , filled with graphite or elastic hard metals to ensure a better hermetic seal and simultaneously reduce mechanical friction between the seals 5b and the inner wall of the housing 5c of the pump 5.

[0068] Upon exiting the pump 5, the hot, compressed mixture of working fluid and heating fluid is sent via the conduit c9 into the separator 8, which is preferably a drip separator. Different possible paths for bringing the working fluid and heating fluid from inside the separator 8 back into the heat engine 2 are described below.Operating mode of the heat exchanger 7

[0069] Inside the separator 8, the working fluid and heating fluid are separated from each other. At this point they are both, for example, at a pressure of about 150 bar.

[0070] The working fluid in supercritical conditions is guided into the heat engine 2 via the conduit c19.

[0071] In contrast, all or at least part of the heating fluid can be sent from the separator 8 directly into the heat engine 2 and / or be heated before being sent into the heat engine 2 and / or be heated before being sent into the pump 5 and / or be sent directly into the pump 5.

[0072] If the heating fluid is sent directly into the heat engine 2, upon exiting the separator 8 it will pass through the valve v6, the conduit c10 and the conduit c11 and enter the engine 2 via the conduit c12.

[0073] If the heating fluid is further heated before being introduced into the engine 2, upon exiting the separator 8 it will pass through the separator 8 via the valve v6 and enter the heat exchanger 7 via the conduit c13. Said exchanger can be connected to the circuit of a solar system comprising, for example, a surface covered by solar panels 11 and a reservoir 10 for storing thermal energy. The fluid of the solar system circulates in the conduits c15, being moved by the pump 12, and, in the heat exchanger 7, through additional exchangers in series and / or in parallel contained in the heat exchanger 7 (not illustrated), it transfers heat to the heating fluid of the system 1. The advantage of the solar system is that the solar irradiation which would otherwise increase the entropic load can be exploited within the system of the invention, thus further increasing the advantageous effects of the invention. In particular, by covering as much as possible the surface occupied by the system of the invention, which is located, for example, inside a building, one succeeds in obtaining an optimal reduction of the entropic load.

[0074] Furthermore, the heat exchanger 7 can be connected to a burner 16, preferably a pore burner. The burner can be, for example, supplied with fuel from a fuel reservoir 17. From the reservoir the fuel is sent into the burner 16 via the conduit c14 and valve v7. The heat produced by the burner 16 is transferred to the heating fluid via the heat exchanger 7. Biomasses, such as biomethane, wood pellets, ethanol, and natural gas can be used, for example, as fuel. Furthermore, the burner can carry out catalytic oxidation for the reduction of pollutants.

[0075] The heating fluid may also be heated in the heat exchanger 7 by the hot working fluid. The working fluid can in fact be drawn from the heat exchanger 4 via the conduit c16b and have further pressure and heat added to it by a heat pump 13. Continuing in the conduit c16c, the working fluid can arrive, via the conduit c16d, at the heat exchanger 7, transfer heat to the heating fluid and then, continuing in the conduit c16e, be introduced into the heat engine 2 via the conduit c16f.

[0076] If it becomes necessary to exchange additional heat with the hot water circuit CO-ac, the working fluid, after exiting the heat pump 13, can pass through the conduit c16c and be directed into the conduit c16g (valves for diverting the working fluid from the conduit c16c to the conduit c16g not represented in Fig. 1), transfer heat to the circuit CO-ac in the heat exchanger 3 and exit said exchanger using the conduit c16h.

[0077] The heating fluid, heated according to one or more of the methods listed above, can be brought, entirely or in part, into the pump 5 via the conduit c17 and the valves v8 and v9. In this manner, the heating fluid is preferably introduced into the first and / or fourth stage of said pump.

[0078] Furthermore, the hot heating fluid can be brought, entirely or in part, into the heat engine 2 directly via the valve v10, the conduit c18, the conduit c11, and the conduit c12.

[0079] After the heating fluid and / or working fluid have been reintroduced into the heat engine 2, the work cycle of the system 1 is repeated according to the processes illustrated previously.

[0080] Additional pumps, conduits and valves not specified in the previous description of Fig. 1, but nonetheless represented in Fig. 1, can be used to bring about further diversions of the working fluid and / or heating fluid not limited to the ones illustrated previously.Structure and operation of the heat engine 2

[0081] Fig. 2a shows a section of a detail of a heat engine 2 comprising concentric gears 18a and 18b with straight teeth D (only one tooth is indicated by "D" in Figs. 2a and 2b for the sake of drawing simplicity). The teeth D define working chambers 20 for expanding the fluid.

[0082] Within the scope of this invention, a working chamber 20 is considered as a volume defined between teeth, not necessarily adjacent, and comprised inside the heat engine 2, in which the working fluid or working fluid mixture is expanded or compressed. This volume can be defined, for example, by the contact of dynamic gas seals 21 and / or blades 19 of the teeth D with the wall of the internal chamber of the heat engine 2 and / or with seals present thereon. In a working chamber 20 defined in this manner, an isothermal expansion can be achieved.

[0083] Alternatively, for example at the inlet of the conduit c19 in the heat engine 2, this volume can be defined between: the tooth D of a first gear, for example 18a, having its own dynamic gas seal 21 or its own blade 19 in contact with the inner wall of the engine or with a seal thereon; the tooth D of a second gear, for example 18b, having its own dynamic gas seal 21 or its own blade 19 in contact with the inner wall of the engine or with a seal thereon; the tooth D of the first gear, for example of 18a, and the tooth D of the second gear, for example 18b, in contact with each other. In a working chamber defined in such a manner, an isobaric filling of the heat engine can be achieved, for example by introducing the fluid or mixture from the conduit c19. The heat engine 2 can be a valveless fluid machine, also called an expansion machine. In the heat engine 2, the working fluid or the mixture of working fluid and heating fluid enters via the conduit c19 and causes a direct thrust on the teeth D of the gears 18a and 18b. The direct thrust of the fluid on the teeth in the pressure zone 22 causes the gears 18a and 18b to start rotating. The rotation is transmitted to the current generator or alternator 15 by means of at least one mechanical shaft.

[0084] An innovative feature of the gears 18a and 18b is that their teeth D are provided with dynamic gas seals 21, rather than seals only for liquids as per the prior art. All the teeth D are provided with seals 21, even though not all the teeth D are represented with seals 21 in the figures for the sake of drawing simplicity.

[0085] One of the technical effects of said seals is to render the working chambers 20 dynamically impermeable to gas and hence to the fluid in a supercritical phase that is expanded therein, which otherwise could not be processed in the heat engine 2.

[0086] Furthermore, by means of the seals 21, fluids can be processed at a higher pressure in the heat engine 2; therefore, the efficiency and work produced are increased. The seals 21 can be made, for example, of polytetrafluoroethylene (PTFE), i.e. Teflon ®< , filled with graphite or elastic hard metals to ensure a better hermetic seal and simultaneously reduce mechanical friction between the seals 21 and the inner walls of the heat engine 2.

[0087] Fig. 2b shows a detail of gears of a variant of Fig. 2a, comprising grooves 24 between one tooth and the other. One of the technical effects of said grooves is to capture liquids, preferably the liquid heating fluid. In this manner, the liquid, despite being under high temperature and pressure conditions, will not cause damage to the gears. The grooves can preferably have a depth and / or width on a millimetric scale and can preferably be dimensioned based on the module of the gears. Furthermore, the grooves can preferably be connected to additional dynamic elements 25, comprising transverse grooves forming a labyrinth in which the captured liquid flows. The dynamic elements 25 carry the fluid to the grooves 24. From these grooves, the liquid is conveyed by entrainment, for example by means of the teeth D or the blades 19, towards the conduit c1 through which it exits the heat engine 2.

[0088] One may consider a rotation angle of 0° in the ideal segment connecting the rotation centers of the gears, for example 18a and 18b in Fig. 2a, of the heat engine 2. In every embodiment, the filling of the heat engine 2 can preferably take place with a rotation angle of +10° to +225° or -10° to -225° to favour isobaric filling of the heat engine 2. It is more preferable that the filling of the heat engine 2 takes place with an angle of +180° to +225° or -180° to - 225°.

[0089] Fig. 3 shows a detail of a further embodiment of the heat engine 2. Said engine comprises eccentric gears 23a and 23b, which are arranged so as to mesh with each other and have straight teeth D (only one tooth is indicated by "D" in Fig. 3 for the sake of drawing simplicity). One technical effect of the eccentricity of the gears is that the expansion volume is increased.

[0090] An additional feature of the teeth D is that they can be preferably provided with blades 19 (numbered only for the gear 23a but also illustrated for the gear 23b). Said blades are not essential for the operation of the invention but are in any case a novelty with respect to the prior art regarding heat engines and one of their technical effects is to increase the surface of the working chambers 20 comprised between the teeth D of the gears 23a and 23b. In fact, the blades 19 enable a further expansion of the mixture of working fluid in a supercritical phase and heating fluid compared to a gear without blades. Consequently, a constant high torque on the mechanical shaft is obtained. Thus, the efficiency increases by about 30% (considering a 200kW heat engine, i.e. for industrial rather than domestic applications) and about 50% more work is produced compared to conventional machines. The blades 19 are mounted inside radial slots cut into the gears 23a and 23b. The blades 19 are movable inside these slots: they come out of the gear to the extent necessary to come into contact with the inner wall of the heat engine 2 to create a dynamic gastight seal, for example in the event that eccentric gears 23a and 23b are used. Either a blade 19 or a dynamic gas seal 21 can be mounted on a tooth D. The blades 19 are not necessary on all the teeth D, as shown in the example in Fig.3. Rather, the number of teeth on which it is necessary to mount blades 19 instead of dynamic gas seals 21 varies based on the mutual arrangement of the gears 23a and 23b, their size relative to the size of the internal chamber of the heat engine 2, the number of teeth D and the number of conduits leading into or out of the internal chamber of the heat engine 2.

[0091] Fig. 4 (cross section detail) shows a detail of a possible embodiment of the heat engine 2, wherein the gears 26a and 26b with helical teeth D are mounted on the shaft 27 and are divided by a separator element 28, which is held in position by assembly screws (V). Said separator element is innovative, as it is not used in the prior art of hydraulics. In the present invention, by contrast, it allows the mixture of working fluid in a supercritical phase and heating fluid to be more evenly distributed between the gears 26a and 26b. In fact, the mixture enters through the inlet IN and is distributed between the gears, as shown by the arrows in the inlet IN in Fig. 4. Then the mixture, by applying direct pressure on the teeth D, sets the gears 26a and 26b in motion. In this manner, said gears are subjected to force equally and it is possible to work at higher temperatures and pressures. Consequently, the efficiency and work produced are increased. Subsequently, the mixture exits the heat engine 2 through one of the outlets OUT (only one outlet OUT is shown in Fig. 4 for the sake of drawing simplicity). The inlet IN is preferably a de Laval nozzle. A pressure distributor can preferably be inserted between the inlet IN and the separator element 28 to improve the uniform redistribution of the fluid in the inlet IN between the two gears 26a and 26b.

[0092] Figs. 5a (cross section) and 5b (section obtained by cutting along the line A-A in Fig. 5a) show details of a possible embodiment of the heat engine 2, wherein the concentric gears 29a and 29b have double helical teeth D. The working fluid or the mixture enters the gears through the inlet IN and, after having undergone an isothermal expansion, exits through the outlets OUT. To date, said type of teeth D has been used in the field of hydraulics but not in the field of heat engines. One of the technical effects of using double helical teeth D is to redistribute the entire pressure according to two radial forces. In this manner, no axial force components are formed and the stress on the bearings is reduced. Consequently, the heat engine 2 is quieter during operation and the torque is increased. Therefore, the efficiency and work produced are also increased.

[0093] Fig. 6a (cross section) and Fig. 6b (section obtained by cutting along the line A-A of Fig. 6a) show a possible embodiment of the heat engine 2, wherein three concentric gears 30a, 30b, 30c with double helical teeth D are used. Said gears are set in motion by the shaft 31 and, to increase efficiency, they can be heated by the heat exchangers 32. The use of three gears instead of two is found in the prior art of the field of hydraulics, but not in the field of heat engines. One of the advantages of using three gears is that the working fluid can be introduced via at least two parallel conduits 33a and 33b. Therefore, the power created is doubled compared to the case with only two gears. Therefore, the work produced is doubled, whilst the volume occupied by the heat engine 2 remains compact.

[0094] Fig. 7 shows details of a possible embodiment of the heat engine 2, wherein the generator or alternator (not illustrated in detail, as it is comprised in the prior art) is connected to the heat engine 2 via gastight flanges with special gaskets. The optimal number of revolutions is defined by a reduction gear 34. Said reduction gear is rendered hermetic by means of a device (not illustrated) mounted inside it for a hermetic seal according to the prior art.

[0095] Fig. 8 shows details of a possible embodiment of the heat engine 2, wherein two heat machines M1 and M2 having gears with straight teeth D are present. The heat engine 2 is then hermetically connected to the generator or alternator via the hermetic reduction gears 35a and 35b. An advantage of using two heat machines instead of only one is that double the power can be produced and the efficiency increased. An advantage of arranging the components as in Fig. 8, including the hermetic connections, is that the system is compact and resistant. Therefore, it can also be used for mobile energy production, for example on ships, lorries, loading units, etc.

[0096] Fig. 9 shows details of a possible embodiment of the heat engine 2 similar to the one in Fig. 8, but wherein the heat machines M3 and M4 have gears with double helical teeth D. Therefore, as illustrated previously, there is no axial stress on the bearings. Furthermore, said engine, like the one shown in Fig. 8, can be used for mobile energy production.Thermodynamic cycles carried out according to the present invention

[0097] Fig. 10a shows a thermodynamic cycle by means of a pressure-volume (P,V) diagram and Fig. 10b shows the corresponding temperature-entropy (T,S) diagram, as implemented by one embodiment of the system 1 on the working fluid in winter, i.e. with an ambient temperature below 22 °C. The working fluid is preferably carbon dioxide.

[0098] From state 1 to 2, the working fluid in a supercritical phase undergoes an isothermal expansion in the heat engine 2. From state 2 to 3', the fluid transfers heat isobarically into the heat exchanger 3. Furthermore, the fluid can preferably be subjected to isothermal cooling, which converts it from state 3' to 3. During this conversion, only optional and not essential for the purposes of the invention, the fluid transfers additional heat isothermally into the heat exchanger 4, condensing in a liquid collection sump comprised in said heat exchanger. One of the advantages of carrying out this conversion is to further decrease the volume prior to the isochoric compression and thereby increase the work produced by the system. From state 3 to 1, the working fluid is isochorically compressed by the pump 5. From state 1 the cycle is repeated.

[0099] Fig. 11a shows a thermodynamic cycle by means of a pressure-volume (P,V) diagram and Fig. 11b shows a corresponding temperature-entropy (T,S) diagram, as implemented by one embodiment of the system 1 on the working fluid in summer, i.e. with an ambient temperature above 22 °C. The working fluid is preferably carbon dioxide.

[0100] From state 1 to 2, the working fluid in supercritical phase undergoes an isothermal expansion in the heat engine 2. Thereafter, the expansion can preferably be continued isentropically, passing from state 2 to 3. This isentropic expansion is only optional and not essential for the purposes of the invention. One of the advantages of carrying out said isentropic expansion is that the work produced by the heat engine 2 is further increased. From state 3 to 4, the fluid transfers heat isobarically into the heat exchanger 4, condensing in the liquid collection sump comprised in said heat exchanger. From state 4 to 1, the fluid is isochorically compressed by the pump 5.

[0101] Fig. 12 shows two thermodynamic cycles by means of a temperature-specific entropy (T,s) diagram according to one embodiment of the invention. These cycles pass respectively through states a-b-c and 1-2-3-4-5-6 and are implemented by one embodiment of the system 1 on the working fluid, the system being coupled with a heat pump 13. The working fluid is carbon dioxide. According to this cycle, 400 V of electricity can be produced. Furthermore, the hot water of a consumer can be heated to 70-110 °C and the cold water of a consumer can be cooled to 6-12 °C.

[0102] Cycle a-b-c is considered. From state a to state b an isothermal expansion of the working fluid takes place in the heat engine 2. From state b to state c, the working fluid transfers heat in the heat exchanger 3. From state c to state a, the working fluid is isochorically compressed in the pump 5.

[0103] Cycle 1-2-3-4-5 is started by the heat pump 13, which compresses the fluid and takes place according to the prior art. In particular, from the heat pump 13, the fluid can for example be sent into the heat exchanger 4 and / or 3 and then into the heat engine 2, in order to return directly into the heat pump 13 via the conduits shown in Fig. 1.

[0104] Fig. 13 shows two thermodynamic cycles by means of a temperature-specific entropy (T,s) diagram according to one embodiment of the invention. These cycles pass respectively through states 1-2-3-4-5 and states 1'-2'-3'-4'-5'-6' and are implemented by one embodiment of the system 1 on the working fluid, the system being coupled with a heat pump 13. The working fluid is carbon dioxide.

[0105] The cycle 1-2-3-4-5 is considered. From state 1 to state 2 an isothermal expansion of the fluid takes place in the heat engine 2. From state 2 to 3, the fluid transfers heat in the heat exchanger 3, preferably isobarically. From state 3 to 4, the fluid transfers additional heat in the heat exchanger 4. From state 4 to 5, the working fluid is compressed by the pump 5. From state 5 to 1, an isobaric filling with the fluid takes place, for example of the first stage of the heat engine 2. As regards the cycle 1'-2'-3'-4'-5'-6', it takes place in a similar manner to the cycle 1-2-3-4-5-6 described previously and shown in Fig. 12.

[0106] Fig. 14 shows two thermodynamic cycles by means of a pressure-specific entropy (P,s) diagram according to one embodiment of the invention, in which a heat engine 2 having two heat machines is used, similarly to what is shown in Figs. 8 and 9. The cycle A-B-C-C'-D is carried out by one of the two heat machines, whilst the cycle 1-2-3-3'-4 is carried out by the other.

[0107] The cycle A-B-C-D is considered; it is started by the heat pump 13, which compresses the fluid, and takes place according to the prior art.

[0108] The cycle 1-2-3-3'-4 is considered. From state 1 to state 2, an expansion takes place in the heat engine 2. From state 2, through states 3 and 4, the fluid transfers heat in the heat exchanger 3, condensing in the liquid collection sump contained in said heat exchanger. From state 4 to 5, the fluid is compressed in the pump 5 and filling of the heat engine 2 takes place from state 5 to 1.Description of some advantageous operating conditions obtainable using the system 1

[0109] Fig. 15 shows the temperature T and entropy S states through which the fluids used in conventional organic Rankine cycle systems pass, and the states through which carbon dioxide passes if used as the working fluid in the system 1 according to the present invention. The fluids used in conventional systems are for example water, isopentane, R11, and R152a. The disadvantage of such fluids is that they must be brought to very high temperatures in order to be able to produce satisfactory amounts of energy. In contrast, the carbon dioxide in the system 1 produces energy in the form of work and heat in order to generate electricity, heating and cooling, despite being used as a fluid in a supercritical phase at much lower temperatures compared to the fluids in conventional systems. Therefore, if carbon dioxide is used as the working fluid in the system 1, the risk of producing thermal pollution is further reduced.

[0110] Fig. 16 shows a comparison of the work and heat produced by the system 1 with those produced by a conventional organic Rankine cycle system and the work produced by a system according to patent application DE 10 2017 002 286 A1. Systems with a power of 30 kW are considered. In particular, it is noted that the cycle according to the present invention, based on Figs. 10 and 11, enables a high amount of work L1 to be generated, while having the advantage that such work is produced at lower temperatures than the work L3 produced by the system based on DE 10 2017 002 286 A1 and the work L2 produced by a conventional organic Rankine cycle system. Specifically, the work and the thermal energy provided by the present invention are produced while remaining substantially below the increase in entropy generated under the natural process. Therefore, unlike conventional systems, they do not cause environmental pollution. Furthermore, the useful heat Q1 for heating and the energy for cooling Qf1 generated by the present invention are obtained while producing an amount of entropy that has a negligible impact on the environment. In contrast, the useful heat Q2 generated by conventional organic Rankine cycle systems is obtained while producing a larger amount of entropy than is produced by the natural process and thus causes climate warming. Furthermore, conventional organic Rankine cycle systems produce waste heat Qwaste, which further exacerbates the climate warming caused by such systems.

[0111] Fig. 17 shows the advantageous operating conditions of the heat engine 2 having gears with double helical teeth D. It is noted that about 1500 revolutions per minute are considered an average operating speed for the heat engine 2. The diagram illustrates that, starting from a stationary engine 2 and increasing the number of revolutions per minute, the torque M increases and eventually already becomes constant for 260 revolutions per minute. This occurs because of the double helical shape of the teeth D and enables efficiency to be increased. Again because of the shape of the teeth D and if carbon dioxide is used as a working fluid, the heat Q produced in the engine 2 will grow with the increase in the number of revolutions, but in any case remains lower than the heat produced by conventional processes, and the environmental impact is thus reduced. As regards the power P generated, it grows steeply with the increase in the number of revolutions, unlike the power produced with conventional organic Rankine cycle systems, which ceases growing and already remains constant at a smaller number of revolutions.

Claims

1. A system (1) for producing work, heating and / or cooling, comprising a heat engine (2) for producing mechanical work, having a plurality of gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c) provided with teeth (D), defining working chambers (20) for expanding a fluid, and arranged to mesh with each other, a generator or alternator (15), connected to the gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c) of the heat engine (2) by means of at least one mechanical shaft, for converting into electric current the mechanical work of rotation of the gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c) induced by the direct thrust of the fluid on the teeth (D), a heat exchanger (3, 4), connected via a conduit to the heat engine (2), to cool and / or heat the fluid, a pump (5) having a plurality of compression stages for compressing the fluid and connected via a conduit to the heat exchanger (3, 4) and via a further conduit to the heat engine (2), a motor (14) to drive the pump (5); the system (1) being characterized in that the teeth (D) of the gears (18a, 18b; 23a, 23b; 26a, 26b; 29a, 29b; 30a, 30b, 30c) of the heat engine (2) are provided with dynamic gas seals (21) between the working chambers (20) to keep the fluid, which is in supercritical conditions, confined in a single working chamber (20) while it expands between the teeth (D) that form the working chamber (20); and the stages of the pump (5) are provided with dynamic gas seals (5b) between one stage and the other to keep the fluid, which is in supercritical conditions, confined to a single stage while it is compressed.

2. System (1) according to claim 1, comprising a separator (6, 8), connected via a conduit to the heat engine (2) and via a further conduit to the pump (5), for the separation of the fluid into two distinct fluid parts, in the event that the fluid is a mixture, preferably of carbon dioxide and water containing additives.

3. System (1) according to claim 1 or 2, wherein the gears (18a, 18b, 23a, 23b, 26a, 26b, 29a, 29b, 30a, 30b, 30c) of the heat engine (2) have grooves (24) on the surface between one tooth (D) and the other for the capture of liquids.

4. System (1) according to one of the above claims, comprising a circuit (CO-ac, CO-af) of a consumer (CO) connected to the heat exchanger (3, 4) to provide cooling and / or heating to the consumer (CO).

5. System (1) according to one of the above claims, further comprising a heat pump (13) located on a conduit between the heat exchanger (3, 4) and the heat engine (2) to compress at least part of the fluid before that part enters the heat engine (2).

6. System (1) according to one of the above claims, where the heat exchanger (4) comprises a liquid collection sump to collect at least a part of the fluid while that part condenses, before the fluid is sent to the pump (5) through a conduit or to the heat pump (13) through an additional conduit.

7. System (1) according to one of the above claims, further comprising a solar system connected to an additional heat exchanger (7) to supply heat to at least a part of the fluid before that part enters the heat engine (2) and / or pump (5).

8. System (1) according to one of the above claims, further comprising a burner (16) connected to a heat exchanger (7) to supply heat to at least a part of the fluid before that part enters the heat engine (2) and / or pump (5).

9. A method for producing work, heating, and / or cooling using a fluid, characterized by - an isothermal expansion of the fluid, preferably carbon dioxide, which is in a supercritical phase, - an isobaric cooling of the fluid and - an isochoric compression of the fluid.

10. Method according to claim 9, characterized in that an isentropic expansion is achieved between the isothermal expansion and the isobaric cooling.

11. Method according to claim 9, characterized in that isothermal cooling is achieved between the isobaric cooling and isochoric compression.

12. Method according to one of claims 9-11, characterized in that the isothermal expansion occurs in a heat engine (2), the isobaric cooling occurs in a heat exchanger (3, 4) and the isochoric compression occurs in a pump (5).

13. Method according to one of claims 9-12, wherein the fluid is a first fluid used as a working fluid, and characterized by the introduction, in addition to the first fluid, of a second fluid as a heating fluid, preferably water comprising at least one of graphite, glycerin, antioxidants, anticorrosives, and antifoaming agents, during the isothermal expansion and / or during the isochoric compression.

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