WO2022180471A1 - Internal combustion engine powered with hydrogen and liquid oxygen - Google Patents

Internal combustion engine powered with hydrogen and liquid oxygen Download PDF

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Publication number
WO2022180471A1
WO2022180471A1 PCT/IB2022/051151 IB2022051151W WO2022180471A1 WO 2022180471 A1 WO2022180471 A1 WO 2022180471A1 IB 2022051151 W IB2022051151 W IB 2022051151W WO 2022180471 A1 WO2022180471 A1 WO 2022180471A1
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WO
WIPO (PCT)
Prior art keywords
volumetric
hydrogen
machine
oxygen
motive machine
Prior art date
Application number
PCT/IB2022/051151
Other languages
French (fr)
Inventor
Mario Gaia
Roberto Bini
Original Assignee
Turboden S.p.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Turboden S.p.A. filed Critical Turboden S.p.A.
Priority to EP22707845.8A priority Critical patent/EP4298327A1/en
Publication of WO2022180471A1 publication Critical patent/WO2022180471A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B43/00—Engines characterised by operating on gaseous fuels; Plants including such engines
    • F02B43/10—Engines or plants characterised by use of other specific gases, e.g. acetylene, oxyhydrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/005—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for draining or otherwise eliminating condensates or moisture accumulating in the apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/0205—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust using heat exchangers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
    • F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B43/00—Engines characterised by operating on gaseous fuels; Plants including such engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B47/00—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines
    • F02B47/04—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines the substances being other than water or steam only
    • F02B47/06—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines the substances being other than water or steam only the substances including non-airborne oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B47/00—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines
    • F02B47/04—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines the substances being other than water or steam only
    • F02B47/08—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines the substances being other than water or steam only the substances including exhaust gas
    • F02B47/10—Circulation of exhaust gas in closed or semi-closed circuits, e.g. with simultaneous addition of oxygen

Definitions

  • the present invention relates to an innovative volumetric motive machine which adopts a thermodynamic cycle similar to a Diesel cycle.
  • the machine is preferably powered with hydrogen as fuel and with liquid oxygen as oxidizer, and can therefore be used for the generation of energy from a combined hydrogen and oxygen source.
  • the energy produced can be used, by way of example, in electrical energy storage systems in the phase of returning energy to the network and/or for the mechanical propulsion of naval units, for example ships for the transport of hydrogen.
  • the thermal energy produced by the combustion gases can be used as a thermal source in plants for the production of further electrical energy, for example in organic Rankine cycle (ORC) plants.
  • ORC organic Rankine cycle
  • the volumetric machine is be free of harmful exhaust emissions, has good thermodynamic efficiency and is be economically competitive with respect to other "clean" hydrogen- powered energy sources, such as systems with fuel cells.
  • renewable energy systems e.g. photovoltaic fields and wind turbine clusters
  • knocking according to the well-known English terminology
  • the oxidizer i.e. air.
  • US 3,608,529A describes an internal combustion engine powered with hydrogen or gasoline and provided with a system for recovering and re-circulating the water coming from the exhaust duct.
  • US3,862,624A discloses an internal combustion engine which uses oxygen and an excess of hydrogen and has a substantially closed exhaust system which re-circulates the gaseous portion of the exhaust through the engine and discharges only water.
  • Document US4112875A describes a hydrogen-oxygen powered internal combustion engine, which uses an inert gas, such as argon, as a working fluid to increase engine efficiency, eliminate pollution and facilitate the operation of a closed loop energy system.
  • an inert gas such as argon
  • document GB 398,367 in the name of Fritz von Opel describes an internal combustion engine for use on submarines etc. which adds liquid oxygen to the exhaust products to create the gaseous charge for the next explosion.
  • the condensate in the gases resulting from the addition of oxygen is separated in a container.
  • the condensate can be removed from the separators by means of an overpressure valve or by means of a pump.
  • the container and pump can be driven by turbines.
  • the adoption of hydrogen as a fuel involves, compared to engines powered with natural gas, a lower energy content of the air/fuel mixture introduced into the machine: in fact, hydrogen has a lower density than other gaseous fuels, only partially compensated by the higher energy per mass unit. This difference can be partially compensated for by increasing the compression ratio of the turbocharger upstream of the internal combustion engine.
  • the inherent limitation is due to the fact, that the starting pressure upstream of the turbocharger is necessarily the atmospheric pressure.
  • a scope of the present invention is to define an innovative volumetric motive machine which operates according to a thermodynamic cycle similar to a Diesel cycle, which is preferably powered with hydrogen as a fuel or alternatively with ammonia (NH3) and/or with other fuel which uses oxygen as an oxidizer, preferably in the liquid phase, in order to increase the specific power per engine displacement unit.
  • a thermodynamic cycle similar to a Diesel cycle, which is preferably powered with hydrogen as a fuel or alternatively with ammonia (NH3) and/or with other fuel which uses oxygen as an oxidizer, preferably in the liquid phase, in order to increase the specific power per engine displacement unit.
  • NH3 ammonia
  • the present invention also proposes to increase the overall efficiency of the energy transformation due to the adoption of the Diesel scheme with a high compression ratio, to reduce the cost per kWh of the electrical energy produced and to further reduce the (still minimal) emission of pollutants of reciprocating engines powered with hydrogen, by the use of liquid oxygen instead of air.
  • a volumetric motive machine which operates according to a thermodynamic cycle similar to a Diesel cycle, which is preferably powered with hydrogen and uses oxygen as an oxidizer, which is compressed in a liquid phase pump, wherein the volumetric motive machine has the characteristics set out in the independent claim attached to this description.
  • FIG. 1 schematically illustrates a Diesel cycle volumetric driving machine in a four-stroke configuration, equipped with an auxiliary system for recovering thermal energy at the exhaust, according to a first embodiment of the present invention
  • FIG. 2 schematically illustrates, in a second embodiment of the present invention, a volumetric Diesel cycle motive machine in a two-stroke configuration, equipped with an organic Rankine cycle plant (Organic Rankine Cycle, abbreviation ORC) for the recovery of the exhaust thermal energy.
  • ORC Organic Rankine Cycle
  • FIG. 3 schematically illustrates a volumetric Diesel cycle motive machine in a two-stroke configuration and with one or more controlled valves, equipped with an auxiliary system for recovering exhaust thermal energy, according to a third embodiment of the present invention
  • FIG. 4 schematically illustrates a Diesel cycle volumetric motive machine in a four-stroke configuration, equipped with an organic Rankine cycle system for the recovery of exhaust thermal energy, wherein the ORC system operates according to a plurality of cascade thermodynamic cycles, according to a fourth embodiment of the present invention
  • Figure 5 illustrates the countercurrent heat exchange curves between the oxygen to be liquefied and the hydrogen to be gasified
  • FIG. 7 illustrates a variant of the plant diagram of Figure 6, in which a further heating of the evaporated hydrogen is performed, followed by an expansion in the turbine
  • FIG. 8 shows a plant scheme for the production of liquid oxygen based on a fractional air distillation process
  • FIG. 9 represents the same plant of Figure 8 in which separate heat exchangers are highlighted respectively for air/nitrogen heat exchange and for air/hydrogen heat exchange,
  • FIG. 10 represents a diagram of an injection system called "hypercritical common rail"
  • FIG. 11 schematically illustrates an example of use of the volumetric motive machine, according to one of the embodiments of the invention, in an electrical network provided with renewable/random energy sources.
  • the present invention relates to a volumetric motive machine in which a cycle equivalent to the known Diesel cycle takes place.
  • a first reactant substantially constituted by air
  • a closed casing for example, a cylinder in which a piston moves
  • this closure can take place either through the closure of valves, or through the movement of walls that close the intake and/or exhaust ports as it occurs, for example, in certain 2-stroke engines or in "Wankel" type machines, or also capsulism engines
  • the compression ratio can typically be high in the 10-20 range.
  • a higher compression ratio can correspond to a higher energy efficiency.
  • Compression takes place in a short time so that the heat exchange with the envelope is a small fraction of the energy required for the compression.
  • a compression close to an adiabatic transformation is thus achieved, wherein the final compression temperature is much higher than the initial one.
  • a second reactant hydrocarbon or other fuel is introduced, with a much higher pressure than that of the first reactant contained in the casing, which rapidly mixes with the first reactant.
  • the first reactant is air and at least a second reactant is a fuel or in any case a substance that can carry out an oxidation reaction by the oxygen present in the air, constitutes the known operation of a Diesel cycle machine.
  • the first reactant admitted to the casing is not air but is substantially hydrogen (3 ⁇ 4 ), whereas the second reactant is substantially oxygen (O 2 ), which is compressed in the liquid state, at a pressure higher than the pressure in the casing and it is initiated to the introduction into the cylinder through the injector.
  • the injection proceeds until the introduction of the established quantity of O2 is obtained, possibly also with a discontinuous modality or in any case with a modulated flow rate.
  • reaction product is substantially made by water in the form of steam at supercritical temperature.
  • the introduced quantity of oxygen is preferably lower than the stoichiometric quantity, so that at the end of the reaction there is a fraction of 3 ⁇ 4 which has not been oxidized.
  • the oxidized part is present as water vapor, H2O.
  • the gas extracted from the casing is cooled by a heat exchange system which transfers heat to a thermal user.
  • the condensed fraction is separated and extracted in the form of liquid water.
  • the non-condensed fraction substantially composed of hydrogen and water vapor, is preferably returned for admission to the casing, possibly through a machine (compressor or expander) capable of modifying its pressure. Alternatively, it can be discharged into the atmosphere after purification and/or oxidation according to known techniques .
  • FIG. 1 the schematic diagram of a four-stroke volumetric motive machine 10 is now described, provided with a cylinder 8, a piston 9 - which operates with periodic motion inside the casing/cylinder so as to generate a chamber inside the periodically variable volume casing, between a minimum volume VI and a maximum volume V2 -, at least one inlet opening 3 with a relative suction valve, at least one discharge opening 4 with a relative discharge valve and a collection system and transferring to a rotating shaft of the mechanical power collected by the piston 9 due to the alternation of the pressures acting on it in the various phases of the thermodynamic cycle carried out in the machine itself, according to the known technique of internal combustion engines, which therefore is not shown in the Figure.
  • a quantity of hydrogen from any source 1 enters the cylinder 8 (for example, evaporation of liquefied gas, gas coming from suitably expanded cylinders or cylinder trucks, gas from hydrogen gas pipelines, gaseous hydrogen from chemical processes, gas from gas-meter etc.) through the intake valve 3.
  • the gas pressure is not necessarily linked to the atmospheric pressure as in the case of the classic Diesel which draws air from the environment at atmospheric pressure.
  • a fraction of the return gas from the machine 10 itself is added to the taken-in hydrogen, through the duct 2.
  • an injection system 5a (essentially comprising a manifold 7 which is the source of the liquid oxygen, an injection pump 6 and at least one injector 5) introduces the right quantity of oxygen, in the form of a high-speed jet.
  • One aspect of the present invention is the liquid phase compression of oxygen, necessary to reach adequate injection pressures (for example, of the order of 200-500 bar) for an effective mixing in the combustion chamber. According to the thermal insulation capacity of the injector nozzle, liquid oxygen or gas will be injected at high pressure from the injector nozzle 5.
  • the oxidation reaction starts naturally in the presence of a high temperature of the compressed gas.
  • the start of the oxidation reaction could be assisted either by the presence of a pre-chamber or of a plurality of walls (as in a "hot head” engine), that is of high temperature environments in which oxygen is injected.
  • the subsequent oxidation reaction leads to the achievement of a final temperature and pressure, the values of which depend primarily on the H2/02 ratio, i.e. on how much excess hydrogen which does not participate in the reaction goes through the cycle.
  • a very high temperature can lead to an excess of heat flow dissipated through the walls (even if the power of the gases emitted should be lower than that of conventional Diesel engines due to the absence of carbonaceous particulate). It can also lead to excessively high exhaust temperatures, which are difficult to manage for the downstream thermal utilization plant, such as an ORC plant.
  • the compression and expansion phases can be differentiated through a timing of the valves which reduces the quantity of gas introduced, so as to obtain a greater expansion and therefore a lower exhaust temperature .
  • the gases exiting through the exhaust duct 12 pass through a heat exchanger forming part of a heat exchange system 13 intended to generate further mechanical power (for example, an ORC plant) and to dispose of the residual heat towards an external cold source 14.
  • a heat exchanger forming part of a heat exchange system 13 intended to generate further mechanical power (for example, an ORC plant) and to dispose of the residual heat towards an external cold source 14.
  • the exhaust gases are sent to a thermal user of another nature.
  • the cooling of the exhaust gases takes place in a first part with the cooling characteristics of a gas mixture, in a second part starting from the dew temperature of the water contained, the cooling curve therefore changes in relation to the progressive condensation of the water content.
  • the power generation system will be designed in such a way as to obtain the maximum recovery efficiency (between 8% and 35% of the power at the shaft of the volumetric motive machine), for example, by adopting multi-level ORC systems, or ORC cascade systems.
  • the cooled gas passes through a further duct 15 carrying liquid water (condensate) with it.
  • the condensate can be separated in a separator 16 with the subtraction of liquid 18.
  • the cycle closes with the return duct 19 which re introduces the hydrogen fraction discharged in excess from the engine back into the engine.
  • This duct can include a machine 19a, for example, a compressor with an external drive, or a turbocharger, the turbine of which is driven by the exhaust gases.
  • a vent 17 can also be provided to remove any possible excess non-condensable and to maintain the optimum pressure level in the return duct 19.
  • the volumetric motive machine 20 is comparable to a Diesel cycle engine in a two-stroke configuration, also in this case it is provided with a heat exchange system, which in this configuration is explicitly shown as an ORC plant (the use of this form of recovery by ORC is to be understood as applicable also to the 4-stroke machine of Fig. 1 as well as the form of recovery illustrated in Fig. 1, which can also be applied to the solution of Fig. 2).
  • FIG. 2 all main components of an ORC organic Rankine cycle plant are schematized: a supply pump 25, a heat exchanger 26 with the function of pre-heater, an evaporator and a possible over-heater of the organic fluid, a turbine 27 (with an electric generator 28 coupled to it or with another operating machine) and a condenser 29.
  • the two-stroke volumetric machine 20 will have characteristics similar to the previous four-stroke volumetric machine 10 and, as in the known art, at least one washing inlet opening 21 and at least one exhaust opening 22 facing the cylinder 23. It should be noted that this machine, having substantially no gaseous exhaust into the atmosphere, is less problematic than the classic two-stroke Diesel engines, which must minimize the production and subsequent expulsion of particulates .
  • a two-stroke Diesel cycle volumetric motive machine 30 is schematically illustrated, which differs from the two-stroke volumetric machine 20 of Figure 2 in that it has a controlled overhead exhaust valve 31. Also in this case an auxiliary plant 32 is provided for recovering the thermal energy at the exhaust.
  • This scheme can be more advantageous in terms of power per displacement unit, as the "washing”, i.e. the expulsion of burnt gas and the introduction of a new gas, is more efficient when carried out with a one-way flow scheme with a controlled valve.
  • a Diesel cycle volumetric motive machine 40 and in a four-stroke configuration is shown, which is equipped with a turbine exhaust expander 41, to produce power and pre-cool the discharged gases before accessing the heat recovery, as well as a heat exchange system for the recovery of thermal exhaust energy.
  • a turbine exhaust expander 41 to produce power and pre-cool the discharged gases before accessing the heat recovery, as well as a heat exchange system for the recovery of thermal exhaust energy.
  • an organic Rankine cycle plant 42 is concerned, operating according to a plurality of thermodynamic cycles at different temperature levels, powered by heat exchangers 43, 44, preferably in series on the exhaust path, which can also include an after-cooler 45.
  • the case proposed here has characteristics which differentiate it with respect to the case of an expander with exhaust turbine of Diesel engines of the known type.
  • a fraction of the exhaust gas flow is separated and partially expelled into the separator 16, so that the remaining re-circulated fraction can receive for the operation of the operating machine 19a just a portion of the power produced, unlike what is achieved in the traditional supercharged (turbocharger) scheme.
  • the power of the turbine 41 will therefore preferably be used to generate electrical energy.
  • the electricity produced will then also be used to drive the machine 19a.
  • This also makes it possible to adopt the optimal angular velocity for the two machines 41 and 19a which operate with very different flow rates and of different chemical species.
  • the turbine 41 can be considered a substantially water vapor turbine. The consequence is a high enthalpy jump through the turbine, which can be effectively used with a turbine preferably of the multistage axial type.
  • the purpose of the introduction of the turbine 41 is also to lower the access temperature to the subsequent thermal recovery phase by the exhaust gas, which is a particularly important aspect when the downstream recovery is carried out through the organic Rankine cycle (ORC), the working fluid of which cannot tolerate wall temperatures close to its thermal stability limit.
  • ORC organic Rankine cycle
  • the multistage axial turbine with low exhaust kinetic energy is advantageous both in terms of the expansion ratio achievable with high efficiency, and in terms of the volumetric flow rate admitted to the exhaust.
  • the volumetric machines proposed will consist of a multiplicity of cylinders, with one or more oxygen injectors for each cylinder.
  • a solution of lower cost and complexity than the scheme with a pump for each injector consists in arranging, according to the scheme known with the "common rail" identification, a multiplicity of injectors connected to a duct supplied by the pump 6 which pressurizes the oxygen in liquid phase.
  • the fraction of the excess flow rate can be re-circulated to the intake of the pump 6 itself. In this case it is necessary to cool the return flow rate to the intake, so as to ensure that the fluid supplied to the pump is supplied in the liquid state and in conditions such as to avoid the occurrence of a cavitation in the pump.
  • Figure 10 shows an injection system scheme 200 which can be identified by the Applicant as a "hypercritical common rail" in which the pump 6 supplies a common line 205 from which the single injectors 201 depart.
  • the proposed scheme is characterized in that between the pump 6 and the common line 205 there is a heat exchanger 203 which transfers heat to the oxygen flow coming from the pump 6, bringing it to a temperature above the critical point and preferably to a temperature close to the maximum temperature compatible with the good mechanical operation of the injectors 201 (the number of injectors can be very high, in relation to the number of cylinders and to the number of injectors per cylinder).
  • the circuit itself is closed with a return duct 206 which is preferably inserted upstream of the heat exchanger 203.
  • a compressor 204 overcomes the pressure drops of the circuit, including those inherent to the heat exchanger on the oxygen side.
  • Any excess flow rate of the pump 6 can be vented through vent 202 and returned (after an appropriate cooling) upstream of the pump 6.
  • the heat extracted from any of the following recovered heat sources is used as the thermal source for the exchanger 203: for example, the cooling liners of the cylinders or the heat available in the exhaust gas flow, preferably through a suitable heat carrier, such as diathermic oil.
  • a suitable heat carrier such as diathermic oil.
  • ducts and vessels are preferably traced with electric heating lines.
  • the heated fluid supply avoids subjecting the circuit and the injectors to cryogenic conditions, which entail difficulties for the materials used.
  • the heat introduced into the oxygen flow upstream of the injection avoids the subtraction of heat at the end of the compression which involves an exergetic loss and a possible reduction in the propagation speed of the flame front in the combustion chamber.
  • crankcase of the machine or the volume present under the piston (9 in Fig. 1.) will certainly receive a leakage flow through the piston rings, therefore it is necessary to avoid that the crankcase receives oxygen from the outside in order to avoid the formation of a dangerous atmosphere.
  • the Applicant believes that the best solution is a pressurization with an inert gas, preferably Argon, to avoid that a leakage towards the cylinder leads to the formation of nitrogen oxides (NOx), as could happen if nitrogen was adopted for the pressurization of the crankcase and of the other points of potential leakage, such as valve cases.
  • NOx nitrogen oxides
  • the proposed volumetric machine can be advantageously supplied with other fuels the composition of which contains, together with hydrogen atoms, also carbon atoms.
  • these may be a hydrogen natural gas, hydrogen gaseous hydrocarbon mixtures, suspensions or vapor of liquid hydrocarbons and gaseous hydrocarbons.
  • a fuel supply is adopted with a fuel containing in some form also carbon or hydrocarbons, it will be essential to adopt a suitable vent flow rate to avoid the accumulation in the casing of C02, CO and of a carbonaceous particulate formed in the high oxidation reaction temperature.
  • the vent 17, previously described can be used.
  • Fuels of potential interest include methylcyclohexane (MCH), studied for example by Chiyoda, a Japanese engineering company, as a compound suitable for the transport and accumulation of hydrogen through a liquid hydrocarbon at room temperature, as well as alcohols such as methanol.
  • MCH methylcyclohexane
  • fuels in particular, methylcyclohexane
  • fuels can also be injected from a further injector into the cylinder, during or at the end of the compression phase.
  • the aforementioned volumetric motive machine advantageously also includes a plant for the production of gaseous hydrogen and oxygen in the liquid phase, as will be better described below.
  • gaseous hydrogen and liquid oxygen suitable for pressurization in the pump 6 consists in the realization of a substantially countercurrent heat exchange between hydrogen to be gasified and oxygen to be liquefied, possibly assisted by expansion phases within the valve (due to the Joule- Thompson effect) or within the turbine (adiabatic cooling), which are optimized according to known techniques.
  • Figure 5 illustrates the heat exchange curves representing the temperature trend of the two fluids as a function of the power exchanged between oxygen to be liquefied and hydrogen to be gasified and shows one of the possible situations of a countercurrent heat exchange, with a pressurization of both flows.
  • the following values are used in the Figure: 10 bar abs for hydrogen and 20 bar abs for oxygen.
  • Figure 6 represents the plant scheme 70 which allows to obtain the process mentioned in Figure 5.
  • the Figure shows a first gaseous oxygen tank 71, a second liquid hydrogen tank 72, hydrogen which is pushed by a pump 73 towards a heat exchanger 74 where it receives in countercurrent heat from oxygen, so obtaining the liquefaction of oxygen and the gasification of hydrogen.
  • the liquid phase oxygen is collected in a third tank 75 and from there it is pushed by means of the pump 6 to the injector 5.
  • the necessary liquid oxygen can be obtained from liquefaction and fractional distillation of atmospheric air, which uses the evaporation of hydrogen supplied to the machine as a cold source.
  • a suitable separator such as one or more distillation columns
  • FIG. 8 The process scheme for this solution is shown in Figure 8 in which in the system 80, in addition to the already known components, a source of compressed and purified air 81 is represented, and a single heat exchanger 82, preferably of the plate type with a plurality of heat exchanging flows ("multi-stream plate- fin heat exchangers") often used in the cryogenic field, in which air is cooled in countercurrent both by hydrogen and by the flow, substantially formed by nitrogen, coming from the separator 83, which can include one or more distillation columns.
  • a source of compressed and purified air 81 is represented, and a single heat exchanger 82, preferably of the plate type with a plurality of heat exchanging flows (“multi-stream plate- fin heat exchangers”) often used in the cryogenic field, in which air is cooled in countercurrent both by hydrogen and by the flow, substantially formed by nitrogen, coming from the separator 83, which can include one or more distillation columns.
  • the air flow coming from the air source 81 can be previously cooled in a heat exchanger 86.
  • the air flow 87 exiting the heat exchanger 86 can be separated into two distinct flows by a flow divider 87a: a first flow 88 is sent to the heat exchanger 84 and a second flow 89 is sent to the heat exchanger 85.
  • the air flow united in a single flow 90 can be cooled in a heat exchanger 91. The heat removed from the air is transferred in this exchanger to the incoming hydrogen flow from the tank 72 and from the pump 73.
  • the air flow contains mainly condensed oxygen.
  • a separator 92 possibly equipped with a distillation column, sends the liquid oxygen to the line 94 and to the air fraction, substantially constituted by nitrogen, to the exchanger 84 through the line 93.
  • Other exchangers can advantageously complete the heat exchange, in particular an exchanger in countercurrent between the two ducts 97 and 96, respectively supplied by nitrogen and by incoming air, suitably purified in 81 as seen above.
  • the liquefaction of the oxygen component of the air is a part of a known cryogenic technique which includes solutions aimed at avoiding damage to the process due to the presence of elements or compounds even in small quantities in the supply air, such as water, argon and other noble gases, C02.
  • a known cryogenic technique which includes solutions aimed at avoiding damage to the process due to the presence of elements or compounds even in small quantities in the supply air, such as water, argon and other noble gases, C02.
  • the two flows of oxygen and air have flow rates, in terms of the fraction of oxygen transported, substantially corresponding to the stoichiometric ratio in combustion.
  • an example of use of the volumetric motive machine 10 is now described, according to one of the embodiments of the invention, in an electrical grid 100 provided with renewable/random energy sources.
  • the electrical grid 100 will be able to supply or absorb electrical power according to the demand for electrical power.
  • an electrolyser 110 may be provided, which will absorb electrical power from the grid 100 to produce hydrogen and oxygen from the electrolysis of water. Hydrogen and oxygen in the gaseous phase will be able to supply fuel cells 120, which will supply electrical power to the grid 100.
  • the volumetric motive machine 10 will also be in electrical connection with the grid 100 and can be dedicated to the absorption of peaks in demand for electrical power required by the network.
  • the electrical powers supplied by the fuel cells and by the volumetric machine may indicatively be of the order of 100 MW.
  • the volumetric motive machine 10 will also be able to deliver thermal power contained in its exhaust gases for a thermal user 130.
  • the main components already described have been also inserted, for supplying the fuel cells 120 and the volumetric machine 10: in particular, a first tank 140 containing liquid hydrogen, a second tank 150 containing liquid oxygen, as well as a first machine 160 and a second machine 170 for liquefaction or re gasification, respectively, of hydrogen and oxygen.
  • a first tank 140 containing liquid hydrogen containing liquid hydrogen
  • a second tank 150 containing liquid oxygen
  • a first machine 160 and a second machine 170 for liquefaction or re gasification, respectively, of hydrogen and oxygen.
  • the machines 160, 170 will be able to work as regasifiers, respectively, of hydrogen and oxygen. If, on the other hand, there is a request for electrical power from the volumetric machine 10, the machine 160 will be able to work as a hydrogen regasifier, while the machine 170 will be able to liquefy the oxygen. On the other hand, when a tank 140, 150 reaches a minimum level of liquid contained in it, respectively, of hydrogen or oxygen, the corresponding machine 160, 170 will be able to carry out the liquefaction of hydrogen or oxygen, also in relation to the forecast of availability of electricity and according to the cost foreseen for the same.
  • a tank 180 is also provided for the possible supply (or integration of supply) of the volumetric machine 10 by means of hydrocarbons (with possible enrichment of hydrogen).
  • the mixture consists of natural gas and hydrogen.
  • the characteristics of the volumetric motive machine according to the present invention in particular, in comparison with fuel cell plants powered by hydrogen and oxygen, for sizes of 10-50 MW and for a time horizon of about twenty years, should be as follows:

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Abstract

Volumetric motive machine (10, 20, 30, 40) working according to an operating sequence substantially equivalent to the Diesel cycle engines, comprising: • - at least one casing (8, 23) for containing a fuel element and an oxidizing element, wherein oxidizing element is oxygen compressed in the liquid phase by one or more pumps (6) before being introduced into the casing (8, 23), • - at least one piston (9) operating with periodic motion inside the casing (8, 23), so as to generate a chamber inside the casing of variable volume periodically between a minimum volume VI and a maximum volume V2, • - inlet openings (3, 21) for the intake of the fuel and exhaust openings (4, 22, 31) for the exhaust of combustion gases produced by the combustion of the fuel with the oxidizing element, • - an injection system (5a, 200) for injecting the oxidizing element into the casing (8, 23), • - at least one inlet duct (1) for the fuel element and at least one exhaust duct (12) for combustion gases, • - a system for collecting and transferring the mechanical power collected by the piston (9) to a rotating shaft by means of the alternation of the pressures acting on it in the various phases of the thermodynamic cycle carried out in the machine itself, whereby the volumetric motive machine (10, 20, 30, 40) is provided with a turbine expander (41) located on the exhaust duct (12) to produce mechanical power and pre-cool the exhaust gases.

Description

INTERNAL COMBUSTION ENGINE POWERED WITH HYDROGEN
AND LIQUID OXYGEN
DESCRIPTION
Technical field of the Invention
The present invention relates to an innovative volumetric motive machine which adopts a thermodynamic cycle similar to a Diesel cycle. The machine is preferably powered with hydrogen as fuel and with liquid oxygen as oxidizer, and can therefore be used for the generation of energy from a combined hydrogen and oxygen source.
In particular, the energy produced can be used, by way of example, in electrical energy storage systems in the phase of returning energy to the network and/or for the mechanical propulsion of naval units, for example ships for the transport of hydrogen.
Advantageously, the thermal energy produced by the combustion gases can be used as a thermal source in plants for the production of further electrical energy, for example in organic Rankine cycle (ORC) plants.
The volumetric machine, according to the present invention, is be free of harmful exhaust emissions, has good thermodynamic efficiency and is be economically competitive with respect to other "clean" hydrogen- powered energy sources, such as systems with fuel cells.
Background art As is known, hydrogen and oxygen are available in large-scale energy storage systems, based on the production of hydrogen from water electrolysis. These two products are often stored on site as compressed gas or as liquefied gas. Storage as a liquid is easier for oxygen, which can be liquefied at a higher temperature than hydrogen and requires a smaller storage volume. The concept of energy storage with hydrogen includes the phases of:
* production of hydrogen using low-cost energy during periods of excess energy production from renewable energy systems (e.g. photovoltaic fields and wind turbine clusters);
* storage in tanks, both in the liquid phase and as a compressed gas, of the hydrogen produced, or of both hydrogen and oxygen, if the latter is also to be used;
* power generation in periods of high power demand, using stored gas.
For the production of electricity, among others, the following solutions can be adopted: (i) gas turbines powered with hydrogen in a combined cycle configuration, (ii) fuel cells and (iii) internal combustion engines powered with hydrogen. The latter have a lower cost per kW installed and are suitable for relatively small installations. However, the typical efficiency is currently lower than other solutions and the maintenance cost is higher. Some internal combustion engines powered with hydrogen, characterized by the compression of a mixture of air and hydrogen and the adoption of spark ignition, are known as used or at least proposed in the literature. The implemented cycle is an Otto cycle, with a volumetric compression ratio limited to about Vi/Vf = 10, due to the need to avoid the feared knocking phenomena ("knocking", according to the well-known English terminology), within a fluid containing both the gaseous fuel, i.e. hydrogen, and the oxidizer, i.e. air. Some examples of internal combustion engines powered with hydrogen are described in some patent documents.
US 3,608,529A describes an internal combustion engine powered with hydrogen or gasoline and provided with a system for recovering and re-circulating the water coming from the exhaust duct.
US3,862,624A discloses an internal combustion engine which uses oxygen and an excess of hydrogen and has a substantially closed exhaust system which re-circulates the gaseous portion of the exhaust through the engine and discharges only water.
Document US4112875A describes a hydrogen-oxygen powered internal combustion engine, which uses an inert gas, such as argon, as a working fluid to increase engine efficiency, eliminate pollution and facilitate the operation of a closed loop energy system.
Finally, document GB 398,367 in the name of Fritz von Opel, describes an internal combustion engine for use on submarines etc. which adds liquid oxygen to the exhaust products to create the gaseous charge for the next explosion. The condensate in the gases resulting from the addition of oxygen is separated in a container. The condensate can be removed from the separators by means of an overpressure valve or by means of a pump. The container and pump can be driven by turbines.
Basically, the adoption of hydrogen as a fuel involves, compared to engines powered with natural gas, a lower energy content of the air/fuel mixture introduced into the machine: in fact, hydrogen has a lower density than other gaseous fuels, only partially compensated by the higher energy per mass unit. This difference can be partially compensated for by increasing the compression ratio of the turbocharger upstream of the internal combustion engine. However, the inherent limitation is due to the fact, that the starting pressure upstream of the turbocharger is necessarily the atmospheric pressure.
There is therefore a need to define an innovative volumetric motive machine preferably powered with hydrogen, which is capable of supplying power in the energy return phase in periodic storage systems, rather than for propulsion systems and which is favorable from costs, dimensions and energy efficiency point of view.
Summary of the Invention In order to substantially solve the technical problems highlighted above, a scope of the present invention is to define an innovative volumetric motive machine which operates according to a thermodynamic cycle similar to a Diesel cycle, which is preferably powered with hydrogen as a fuel or alternatively with ammonia (NH3) and/or with other fuel which uses oxygen as an oxidizer, preferably in the liquid phase, in order to increase the specific power per engine displacement unit.
Together with this result, the present invention also proposes to increase the overall efficiency of the energy transformation due to the adoption of the Diesel scheme with a high compression ratio, to reduce the cost per kWh of the electrical energy produced and to further reduce the (still minimal) emission of pollutants of reciprocating engines powered with hydrogen, by the use of liquid oxygen instead of air.
In addition to the dedicated power storage systems described above, another important field of application is the use of hydrogen for marine propulsion: the adoption of the present invention would require a suitable supply of liquid oxygen in addition to the supply of hydrogen. However, compared to a supply of liquid hydrogen, the supply of cryogenic oxygen (approximately at -180°C and with a density near to that of water or diesel) is less demanding, since liquid oxygen exhibits a lower volume and a higher storage temperature than liquid hydrogen.
In particular, future liquid hydrogen carrier tankers could be a good field of application for the invention.
Therefore, according to the present invention, a volumetric motive machine is provided which operates according to a thermodynamic cycle similar to a Diesel cycle, which is preferably powered with hydrogen and uses oxygen as an oxidizer, which is compressed in a liquid phase pump, wherein the volumetric motive machine has the characteristics set out in the independent claim attached to this description.
Further preferred and/or particularly advantageous embodiments of the invention are described according to the characteristics set out in the attached dependent claims.
Brief Description of the Drawings
The invention will now be described with reference to the attached drawings, which illustrate some non limiting examples of embodiment, in which:
- Figure 1 schematically illustrates a Diesel cycle volumetric driving machine in a four-stroke configuration, equipped with an auxiliary system for recovering thermal energy at the exhaust, according to a first embodiment of the present invention,
- Figure 2 schematically illustrates, in a second embodiment of the present invention, a volumetric Diesel cycle motive machine in a two-stroke configuration, equipped with an organic Rankine cycle plant (Organic Rankine Cycle, abbreviation ORC) for the recovery of the exhaust thermal energy.
- Figure 3 schematically illustrates a volumetric Diesel cycle motive machine in a two-stroke configuration and with one or more controlled valves, equipped with an auxiliary system for recovering exhaust thermal energy, according to a third embodiment of the present invention,
- Figure 4 schematically illustrates a Diesel cycle volumetric motive machine in a four-stroke configuration, equipped with an organic Rankine cycle system for the recovery of exhaust thermal energy, wherein the ORC system operates according to a plurality of cascade thermodynamic cycles, according to a fourth embodiment of the present invention,
Figure 5 illustrates the countercurrent heat exchange curves between the oxygen to be liquefied and the hydrogen to be gasified,
- Figure 6 represents the plant scheme which allows to obtain the heat exchange process of Figure 5,
- Figure 7 illustrates a variant of the plant diagram of Figure 6, in which a further heating of the evaporated hydrogen is performed, followed by an expansion in the turbine, - Figure 8 shows a plant scheme for the production of liquid oxygen based on a fractional air distillation process,
- Figure 9 represents the same plant of Figure 8 in which separate heat exchangers are highlighted respectively for air/nitrogen heat exchange and for air/hydrogen heat exchange,
- Figure 10 represents a diagram of an injection system called "hypercritical common rail", and
- Figure 11 schematically illustrates an example of use of the volumetric motive machine, according to one of the embodiments of the invention, in an electrical network provided with renewable/random energy sources.
Detailed Description
Purely by way of a non-limiting example, the present invention will now be described with reference to the aforementioned Figures.
The present invention relates to a volumetric motive machine in which a cycle equivalent to the known Diesel cycle takes place. In fact, in the Diesel cycle a first reactant, substantially constituted by air, is introduced into a closed casing (for example, a cylinder in which a piston moves), and it is compressed by means of a closure of the casing in which the reactant is contained (this closure can take place either through the closure of valves, or through the movement of walls that close the intake and/or exhaust ports as it occurs, for example, in certain 2-stroke engines or in "Wankel" type machines, or also capsulism engines), together with a progressive decrease in the casing volume.A volumetric compression ratio is identified as the ratio between the initial volume of the first reactant charge and the final volume at the end of the process of reducing the volume contained in the casing, R = Vi/Vf. In the absence of the limit imposed by the knock phenomenon in a Diesel type scheme, the compression ratio can typically be high in the 10-20 range. A higher compression ratio can correspond to a higher energy efficiency. Compression takes place in a short time so that the heat exchange with the envelope is a small fraction of the energy required for the compression. A compression close to an adiabatic transformation is thus achieved, wherein the final compression temperature is much higher than the initial one. Around the point of end of compression (typically with a certain advance compared to the point itself), through a duct called an injector a second reactant, hydrocarbon or other fuel is introduced, with a much higher pressure than that of the first reactant contained in the casing, which rapidly mixes with the first reactant. Due to the high temperature reached by the first reactant because of the compression, a reaction is started between the two reactants, which leads to the formation of third compounds, with a development of the reaction energy. In many machines the injection of the second reactant takes place in a time-modulated manner, in order to obtain a good completion of the reaction. Furthermore, it is possible that more reactants are introduced, for example to obviate the difficulty of initiating the reaction of the reactants (which technique is adopted, for example, in "dual fuel" engines, in which to the air introduced into the casing a fraction of reactant (typically combustible gas) is added and the start of the oxidation reaction is guaranteed by the injection, at the end of the compression, of a small quantity of liquid fuel with easy ignition characteristics.
This is followed by the expansion within the casing, with the collection of the expansion energy of the high temperature gas resulting from the reaction, and the expulsion of the reaction products, through suitable valves or ports.
What has been described, in the case in which the first reactant is air and at least a second reactant is a fuel or in any case a substance that can carry out an oxidation reaction by the oxygen present in the air, constitutes the known operation of a Diesel cycle machine.
In the present invention instead, according to a preferred embodiment, the first reactant admitted to the casing is not air but is substantially hydrogen (¾ ), whereas the second reactant is substantially oxygen (O2), which is compressed in the liquid state, at a pressure higher than the pressure in the casing and it is initiated to the introduction into the cylinder through the injector. The injection proceeds until the introduction of the established quantity of O2 is obtained, possibly also with a discontinuous modality or in any case with a modulated flow rate.
Hydrogen and oxygen react, even due to the high temperature resulting from the compression which can be assimilated to an adiabatic compression, and give rise to reaction products with a very high temperature, in the range 2000-3000 degrees C. The reaction product is substantially made by water in the form of steam at supercritical temperature.
The introduced quantity of oxygen is preferably lower than the stoichiometric quantity, so that at the end of the reaction there is a fraction of ¾ which has not been oxidized. The oxidized part is present as water vapor, H2O.
The gas extracted from the casing, still characterized by a high temperature, is cooled by a heat exchange system which transfers heat to a thermal user. During the cooling, the condensation of a portion of the water vapor produced by the reaction which is the greater, the lower is the temperature reached at the end of the cooling. The condensed fraction is separated and extracted in the form of liquid water. The non-condensed fraction, substantially composed of hydrogen and water vapor, is preferably returned for admission to the casing, possibly through a machine (compressor or expander) capable of modifying its pressure. Alternatively, it can be discharged into the atmosphere after purification and/or oxidation according to known techniques .
With reference to Figure 1, the schematic diagram of a four-stroke volumetric motive machine 10 is now described, provided with a cylinder 8, a piston 9 - which operates with periodic motion inside the casing/cylinder so as to generate a chamber inside the periodically variable volume casing, between a minimum volume VI and a maximum volume V2 -, at least one inlet opening 3 with a relative suction valve, at least one discharge opening 4 with a relative discharge valve and a collection system and transferring to a rotating shaft of the mechanical power collected by the piston 9 due to the alternation of the pressures acting on it in the various phases of the thermodynamic cycle carried out in the machine itself, according to the known technique of internal combustion engines, which therefore is not shown in the Figure.
During the suction phase, a quantity of hydrogen from any source 1 enters the cylinder 8 (for example, evaporation of liquefied gas, gas coming from suitably expanded cylinders or cylinder trucks, gas from hydrogen gas pipelines, gaseous hydrogen from chemical processes, gas from gas-meter etc.) through the intake valve 3. The gas pressure is not necessarily linked to the atmospheric pressure as in the case of the classic Diesel which draws air from the environment at atmospheric pressure. Advantageously, it may be appropriate to work with a higher inlet pressure to obtain more power per unit of displacement. Furthermore, a fraction of the return gas from the machine 10 itself is added to the taken-in hydrogen, through the duct 2.
At the end of the compression (preferably with a certain degree of advance) an injection system 5a (essentially comprising a manifold 7 which is the source of the liquid oxygen, an injection pump 6 and at least one injector 5) introduces the right quantity of oxygen, in the form of a high-speed jet. One aspect of the present invention is the liquid phase compression of oxygen, necessary to reach adequate injection pressures (for example, of the order of 200-500 bar) for an effective mixing in the combustion chamber. According to the thermal insulation capacity of the injector nozzle, liquid oxygen or gas will be injected at high pressure from the injector nozzle 5.
If oxygen is injected in the gaseous phase, it is necessary to optimize the law of variation of the areas in the nozzle (for example, diverging nozzle, plug nozzle, etc.) and take into account that the modulation of the flow rate is affected by the compressibility of the gas. Moreover, the injection of liquid is preferable both to avoid the drawbacks described above, and because it has a greater penetration capacity of the drops. A proper cryogenic tracing of the pipes and the pump is an effective solution.
At this point, in the presence of the two phases, fuel and oxidizer mixed at least locally, the oxidation reaction starts naturally in the presence of a high temperature of the compressed gas. Alternatively, the start of the oxidation reaction could be assisted either by the presence of a pre-chamber or of a plurality of walls (as in a "hot head" engine), that is of high temperature environments in which oxygen is injected.
The subsequent oxidation reaction leads to the achievement of a final temperature and pressure, the values of which depend primarily on the H2/02 ratio, i.e. on how much excess hydrogen which does not participate in the reaction goes through the cycle. A very high temperature can lead to an excess of heat flow dissipated through the walls (even if the power of the gases emitted should be lower than that of conventional Diesel engines due to the absence of carbonaceous particulate). It can also lead to excessively high exhaust temperatures, which are difficult to manage for the downstream thermal utilization plant, such as an ORC plant. Advantageously, the compression and expansion phases can be differentiated through a timing of the valves which reduces the quantity of gas introduced, so as to obtain a greater expansion and therefore a lower exhaust temperature .
The gases exiting through the exhaust duct 12 pass through a heat exchanger forming part of a heat exchange system 13 intended to generate further mechanical power (for example, an ORC plant) and to dispose of the residual heat towards an external cold source 14. Alternatively, the exhaust gases are sent to a thermal user of another nature.
The cooling of the exhaust gases takes place in a first part with the cooling characteristics of a gas mixture, in a second part starting from the dew temperature of the water contained, the cooling curve therefore changes in relation to the progressive condensation of the water content. The power generation system will be designed in such a way as to obtain the maximum recovery efficiency (between 8% and 35% of the power at the shaft of the volumetric motive machine), for example, by adopting multi-level ORC systems, or ORC cascade systems.
The cooled gas passes through a further duct 15 carrying liquid water (condensate) with it. Preferably, the condensate can be separated in a separator 16 with the subtraction of liquid 18. The cycle closes with the return duct 19 which re introduces the hydrogen fraction discharged in excess from the engine back into the engine. This duct can include a machine 19a, for example, a compressor with an external drive, or a turbocharger, the turbine of which is driven by the exhaust gases.
If necessary, a vent 17 can also be provided to remove any possible excess non-condensable and to maintain the optimum pressure level in the return duct 19.
With reference to Figure 2, in this second embodiment of the invention the volumetric motive machine 20 is comparable to a Diesel cycle engine in a two-stroke configuration, also in this case it is provided with a heat exchange system, which in this configuration is explicitly shown as an ORC plant (the use of this form of recovery by ORC is to be understood as applicable also to the 4-stroke machine of Fig. 1 as well as the form of recovery illustrated in Fig. 1, which can also be applied to the solution of Fig. 2). In particular, in Figure 2 all main components of an ORC organic Rankine cycle plant are schematized: a supply pump 25, a heat exchanger 26 with the function of pre-heater, an evaporator and a possible over-heater of the organic fluid, a turbine 27 (with an electric generator 28 coupled to it or with another operating machine) and a condenser 29. The two-stroke volumetric machine 20 will have characteristics similar to the previous four-stroke volumetric machine 10 and, as in the known art, at least one washing inlet opening 21 and at least one exhaust opening 22 facing the cylinder 23. It should be noted that this machine, having substantially no gaseous exhaust into the atmosphere, is less problematic than the classic two-stroke Diesel engines, which must minimize the production and subsequent expulsion of particulates .
With reference to Figure 3, a two-stroke Diesel cycle volumetric motive machine 30 is schematically illustrated, which differs from the two-stroke volumetric machine 20 of Figure 2 in that it has a controlled overhead exhaust valve 31. Also in this case an auxiliary plant 32 is provided for recovering the thermal energy at the exhaust. This scheme can be more advantageous in terms of power per displacement unit, as the "washing", i.e. the expulsion of burnt gas and the introduction of a new gas, is more efficient when carried out with a one-way flow scheme with a controlled valve.
Finally, and with reference to Figure 4, a Diesel cycle volumetric motive machine 40 and in a four-stroke configuration is shown, which is equipped with a turbine exhaust expander 41, to produce power and pre-cool the discharged gases before accessing the heat recovery, as well as a heat exchange system for the recovery of thermal exhaust energy. In this case it is, by way of example, an organic Rankine cycle plant 42 is concerned, operating according to a plurality of thermodynamic cycles at different temperature levels, powered by heat exchangers 43, 44, preferably in series on the exhaust path, which can also include an after-cooler 45.
The addition of a continuous flow expander such as a turbine on the combustion gas transfer duct to the heat recovery system located downstream is obviously advantageous in terms of mechanical power produced, in addition to that obtained by the volumetric machine.
The case proposed here has characteristics which differentiate it with respect to the case of an expander with exhaust turbine of Diesel engines of the known type. In fact, a fraction of the exhaust gas flow is separated and partially expelled into the separator 16, so that the remaining re-circulated fraction can receive for the operation of the operating machine 19a just a portion of the power produced, unlike what is achieved in the traditional supercharged (turbocharger) scheme. The power of the turbine 41 will therefore preferably be used to generate electrical energy.
The electricity produced will then also be used to drive the machine 19a. This also makes it possible to adopt the optimal angular velocity for the two machines 41 and 19a which operate with very different flow rates and of different chemical species. In particular, in the case of supply with a prevalence of hydrogen or ammonia, the turbine 41 can be considered a substantially water vapor turbine. The consequence is a high enthalpy jump through the turbine, which can be effectively used with a turbine preferably of the multistage axial type.
Furthermore, the purpose of the introduction of the turbine 41 is also to lower the access temperature to the subsequent thermal recovery phase by the exhaust gas, which is a particularly important aspect when the downstream recovery is carried out through the organic Rankine cycle (ORC), the working fluid of which cannot tolerate wall temperatures close to its thermal stability limit.Also in this sense, the multistage axial turbine with low exhaust kinetic energy is advantageous both in terms of the expansion ratio achievable with high efficiency, and in terms of the volumetric flow rate admitted to the exhaust.
What has been highlighted for the scheme in Figure 4, with a volumetric machine, also applies to two-stroke motive machines (Figures 2 and 3).
The volumetric machines proposed will consist of a multiplicity of cylinders, with one or more oxygen injectors for each cylinder. A solution of lower cost and complexity than the scheme with a pump for each injector consists in arranging, according to the scheme known with the "common rail" identification, a multiplicity of injectors connected to a duct supplied by the pump 6 which pressurizes the oxygen in liquid phase. In the presence of an excess flow rate of the pump with respect to the sum of the consumptions of the injectors, whether single or multiple, the fraction of the excess flow rate can be re-circulated to the intake of the pump 6 itself. In this case it is necessary to cool the return flow rate to the intake, so as to ensure that the fluid supplied to the pump is supplied in the liquid state and in conditions such as to avoid the occurrence of a cavitation in the pump.
As an alternative to the "common rail" scheme substantially crossed by liquid oxygen, Figure 10 shows an injection system scheme 200 which can be identified by the Applicant as a "hypercritical common rail" in which the pump 6 supplies a common line 205 from which the single injectors 201 depart.
The proposed scheme is characterized in that between the pump 6 and the common line 205 there is a heat exchanger 203 which transfers heat to the oxygen flow coming from the pump 6, bringing it to a temperature above the critical point and preferably to a temperature close to the maximum temperature compatible with the good mechanical operation of the injectors 201 (the number of injectors can be very high, in relation to the number of cylinders and to the number of injectors per cylinder).
To ensure a uniform temperature in the circuit, the circuit itself is closed with a return duct 206 which is preferably inserted upstream of the heat exchanger 203. A compressor 204 overcomes the pressure drops of the circuit, including those inherent to the heat exchanger on the oxygen side.
Any excess flow rate of the pump 6 can be vented through vent 202 and returned (after an appropriate cooling) upstream of the pump 6.
The heat extracted from any of the following recovered heat sources is used as the thermal source for the exchanger 203: for example, the cooling liners of the cylinders or the heat available in the exhaust gas flow, preferably through a suitable heat carrier, such as diathermic oil. To ensure a sufficient fluidity in the heat carrier start-up phases, ducts and vessels are preferably traced with electric heating lines.
The adoption of the "hypercritical common rail" system avoids the risk of supplying the injectors with a fluid having variable characteristics, depending on the operating conditions of the machine, so that there may be an uncertain supply of liquid or a two-phase fluid.
Furthermore, the heated fluid supply avoids subjecting the circuit and the injectors to cryogenic conditions, which entail difficulties for the materials used. Finally, the heat introduced into the oxygen flow upstream of the injection avoids the subtraction of heat at the end of the compression which involves an exergetic loss and a possible reduction in the propagation speed of the flame front in the combustion chamber.
In all configurations presented, the crankcase of the machine or the volume present under the piston (9 in Fig. 1.) will certainly receive a leakage flow through the piston rings, therefore it is necessary to avoid that the crankcase receives oxygen from the outside in order to avoid the formation of a dangerous atmosphere. The Applicant believes that the best solution is a pressurization with an inert gas, preferably Argon, to avoid that a leakage towards the cylinder leads to the formation of nitrogen oxides (NOx), as could happen if nitrogen was adopted for the pressurization of the crankcase and of the other points of potential leakage, such as valve cases.
As an alternative to a supply with a substantially pure hydrogen as fuel, the proposed volumetric machine can be advantageously supplied with other fuels the composition of which contains, together with hydrogen atoms, also carbon atoms.
In particular, these may be a hydrogen natural gas, hydrogen gaseous hydrocarbon mixtures, suspensions or vapor of liquid hydrocarbons and gaseous hydrocarbons.
If a fuel supply is adopted with a fuel containing in some form also carbon or hydrocarbons, it will be essential to adopt a suitable vent flow rate to avoid the accumulation in the casing of C02, CO and of a carbonaceous particulate formed in the high oxidation reaction temperature. For this purpose, the vent 17, previously described, can be used.
For an effective elimination of harmful compounds before venting into the atmosphere, it is advisable to adopt components suitable for obtaining a complete oxidation and more generally a purification of exhaust gases, such as catalytic mufflers and particulate filters, a technique known in the field of air-powered internal combustion engines (Air Breathing Engines). The gas coming out of the vent 17 can advantageously be brought to a temperature suitable for the correct operation of these components by means of a countercurrent heat exchange with the exhaust gases from the manifold 12. It is also possible that, in relation to the particular fuel adopted, it is preferable to adopt an excess oxygen flow rate with respect to the stoichiometric ratio, contrary to what is indicated for a substantial hydrogen supply.
Fuels of potential interest include methylcyclohexane (MCH), studied for example by Chiyoda, a Japanese engineering company, as a compound suitable for the transport and accumulation of hydrogen through a liquid hydrocarbon at room temperature, as well as alcohols such as methanol.
According to a further meaning, fuels (in particular, methylcyclohexane) can also be injected from a further injector into the cylinder, during or at the end of the compression phase.
With reference to the supply of hydrogen and oxygen reactants to the volumetric motive machine object of the invention, it is essential to minimize the energy consumption for the supply of the reactants themselves. Therefore, the aforementioned volumetric motive machine advantageously also includes a plant for the production of gaseous hydrogen and oxygen in the liquid phase, as will be better described below.
For example, in the case of supplying the machine with hydrogen stored in the liquid state and with gaseous oxygen instead pressurized in containers (for example, in cylinder trucks), an efficient solution in order to obtain, on the contrary, gaseous hydrogen and liquid oxygen suitable for pressurization in the pump 6, consists in the realization of a substantially countercurrent heat exchange between hydrogen to be gasified and oxygen to be liquefied, possibly assisted by expansion phases within the valve (due to the Joule- Thompson effect) or within the turbine (adiabatic cooling), which are optimized according to known techniques.
Figure 5 illustrates the heat exchange curves representing the temperature trend of the two fluids as a function of the power exchanged between oxygen to be liquefied and hydrogen to be gasified and shows one of the possible situations of a countercurrent heat exchange, with a pressurization of both flows. The following values are used in the Figure: 10 bar abs for hydrogen and 20 bar abs for oxygen.
Figure 6 represents the plant scheme 70 which allows to obtain the process mentioned in Figure 5. The Figure shows a first gaseous oxygen tank 71, a second liquid hydrogen tank 72, hydrogen which is pushed by a pump 73 towards a heat exchanger 74 where it receives in countercurrent heat from oxygen, so obtaining the liquefaction of oxygen and the gasification of hydrogen. The liquid phase oxygen is collected in a third tank 75 and from there it is pushed by means of the pump 6 to the injector 5.
In Figure 7, a further heating of the hydrogen evaporated in the heat exchanger 76 is added, followed by an expansion in the turbine 77 to obtain mechanical/electrical power, thus recovering part of the energy expended for the gasification of hydrogen itself. The thermal energy for heating can come from the cooling system of the cylinder liners, possibly with an integration with the heat available at the exhaust.
According to a further meaning, the necessary liquid oxygen can be obtained from liquefaction and fractional distillation of atmospheric air, which uses the evaporation of hydrogen supplied to the machine as a cold source. In this case it is necessary that the nitrogen fraction, which remained gaseous downstream of the oxygen condensation, is isolated with a suitable separator (such as one or more distillation columns) and is sent back to cool the incoming air, with a regenerative scheme.
The process scheme for this solution is shown in Figure 8 in which in the system 80, in addition to the already known components, a source of compressed and purified air 81 is represented, and a single heat exchanger 82, preferably of the plate type with a plurality of heat exchanging flows ("multi-stream plate- fin heat exchangers") often used in the cryogenic field, in which air is cooled in countercurrent both by hydrogen and by the flow, substantially formed by nitrogen, coming from the separator 83, which can include one or more distillation columns.
The same scheme is shown in Figure 9, which, in place of the single heat exchanger, two separate heat exchangers are highlighted, a first heat exchanger 84 for air heat exchange/return nitrogen flow and a second heat exchanger 85 for air/hydrogen heat exchange.
Advantageously, the air flow coming from the air source 81 (line 96) can be previously cooled in a heat exchanger 86. The air flow 87 exiting the heat exchanger 86 can be separated into two distinct flows by a flow divider 87a: a first flow 88 is sent to the heat exchanger 84 and a second flow 89 is sent to the heat exchanger 85. Also advantageously at the outlet from the heat exchangers 84 and 85, the air flow united in a single flow 90 can be cooled in a heat exchanger 91. The heat removed from the air is transferred in this exchanger to the incoming hydrogen flow from the tank 72 and from the pump 73. At the outlet from the exchanger 91, the air flow contains mainly condensed oxygen. A separator 92, possibly equipped with a distillation column, sends the liquid oxygen to the line 94 and to the air fraction, substantially constituted by nitrogen, to the exchanger 84 through the line 93. Other exchangers can advantageously complete the heat exchange, in particular an exchanger in countercurrent between the two ducts 97 and 96, respectively supplied by nitrogen and by incoming air, suitably purified in 81 as seen above.
It should be noted, in general, that the liquefaction of the oxygen component of the air is a part of a known cryogenic technique which includes solutions aimed at avoiding damage to the process due to the presence of elements or compounds even in small quantities in the supply air, such as water, argon and other noble gases, C02. In the proposed plant it is necessary to take into account these known techniques and solutions.
It should be noted that the two flows of oxygen and air have flow rates, in terms of the fraction of oxygen transported, substantially corresponding to the stoichiometric ratio in combustion. However, it may be advantageous to maintain a certain amount of liquid oxygen accumulated upstream of the pump 6 which supplies the injectors 5 of the engine, to compensate for any deficiencies in the flow rate supplied to the pump itself, especially in transitory phases.
In general, the production of liquid oxygen from the air can be of great interest as it allows to drastically reduce the costs of the supply and storage logistics of the reactants. This, in the presence of significant incentives for the use of hydrogen, can make plants distributed throughout the territory feasible, e.g. for cogeneration in nursing homes, industries, district heating plants.
With reference to Figure 11, an example of use of the volumetric motive machine 10 is now described, according to one of the embodiments of the invention, in an electrical grid 100 provided with renewable/random energy sources. The electrical grid 100 will be able to supply or absorb electrical power according to the demand for electrical power. In the scheme illustrated in the Figure, an electrolyser 110 may be provided, which will absorb electrical power from the grid 100 to produce hydrogen and oxygen from the electrolysis of water. Hydrogen and oxygen in the gaseous phase will be able to supply fuel cells 120, which will supply electrical power to the grid 100. The volumetric motive machine 10 will also be in electrical connection with the grid 100 and can be dedicated to the absorption of peaks in demand for electrical power required by the network. The electrical powers supplied by the fuel cells and by the volumetric machine may indicatively be of the order of 100 MW. Eventually, the volumetric motive machine 10 will also be able to deliver thermal power contained in its exhaust gases for a thermal user 130. In the diagram in Figure 10, the main components already described have been also inserted, for supplying the fuel cells 120 and the volumetric machine 10: in particular, a first tank 140 containing liquid hydrogen, a second tank 150 containing liquid oxygen, as well as a first machine 160 and a second machine 170 for liquefaction or re gasification, respectively, of hydrogen and oxygen. These machines will be able to work according to one of the two functions, depending on the needs of the network 10. For example, if there is a demand for electrical power from the fuel cells 120, the machines 160, 170 will be able to work as regasifiers, respectively, of hydrogen and oxygen. If, on the other hand, there is a request for electrical power from the volumetric machine 10, the machine 160 will be able to work as a hydrogen regasifier, while the machine 170 will be able to liquefy the oxygen. On the other hand, when a tank 140, 150 reaches a minimum level of liquid contained in it, respectively, of hydrogen or oxygen, the corresponding machine 160, 170 will be able to carry out the liquefaction of hydrogen or oxygen, also in relation to the forecast of availability of electricity and according to the cost foreseen for the same.
Finally, in the scheme of Figure 11 a tank 180 is also provided for the possible supply (or integration of supply) of the volumetric machine 10 by means of hydrocarbons (with possible enrichment of hydrogen). In the example in Figure 10, the mixture consists of natural gas and hydrogen.
The case of ships for the transport of liquid hydrogen is also very interesting, especially taking into account the use of the boil-off fraction of the hydrogen reserve that can be supplied into ducts 1, 2, 19. In particular, it is an interesting application to submarine ships, also in unmanned version, preferably intended for the transport of liquids or gases such as hydrogen and oxygen or for the implementation of mining and/or for cleaning operations of the seabed.
The characteristics of the volumetric motive machine according to the present invention, in particular, in comparison with fuel cell plants powered by hydrogen and oxygen, for sizes of 10-50 MW and for a time horizon of about twenty years, should be as follows:
* Significantly lower cost per kW installed
* Similar electrical efficiency
* Better tolerance towards impurities in the gas * Overall volume occupied by the lower plant
* Power generation with alternator, therefore with the presence of a rotating reserve in the network, and better quality of the energy produced
* Less use of valuable and/or strategic materials
* Easy recycling at the end of working life
* Availability of waste heat at various heat levels.
In addition to the embodiment of the invention, as described above, it is to be understood that numerous other variants exist. It is also to be understood that such embodiments are exemplary only and limit neither the scope of the invention, nor its applications, nor its possible configurations. On the contrary, although the above description allows the skilled person to carry out the present invention at least according to an exemplary embodiment thereof, it must be understood that many variants of the components described are possible, without thereby departing from the scope of the invention, as defined in the attached claims, which are interpreted literally and/or according to their legal equivalents .

Claims

C LAI M S
1. Volumetric motive machine (10, 20, 30, 40) working according to an operating sequence substantially equivalent to the cycle of Diesel engines, hereinafter referred to as the "Diesel cycle" and comprising: - at least a casing (8, 23) for containing a fuel and an oxidizer, in which the oxidizer is oxygen compressed in the liquid phase by one or more pumps (6) before being introduced into the casing (8, 23),
- at least a piston (9) operating with periodic motion inside the casing (8,
23), in order to generate a chamber inside the casing of a volume varying periodically between a minimum volume (VI) and a maximum volume (V2),
- inlet openings (3, 21) for the intake of the fuel and exhaust openings (4,
22, 31) for the discharge of exhaust gases produced by the combustion of the fuel with the oxidizer,
- an injection system (5a, 200) for the injection of the oxidizer into the casing (8, 23),
- at least one supply duct (1) and at least one exhaust duct (12),
- a system for collecting and transferring the mechanical power collected by the piston (9) to a rotating shaft thanks to the alternation of the pressures acting on it in the various phases of the thermodynamic cycle carried out in the machine itself, the volumetric motive machine (10, 20, 30, 40) being characterized in that it is provided with a turbine expander (41) located on the exhaust duct (12) to produce mechanical power and pre-cool the exhaust gases.
2. Volumetric motive machine (10, 20, 30, 40) according to claim 1, wherein the fuel comprises hydrogen in the gaseous phase.
3. Volumetric motive machine (10, 20, 30, 40) according to claim 1, wherein the fuel comprises hydrogen with added hydrocarbons or other fuels which include carbon in their composition.
4. Volumetric motive machine (10, 20, 30, 40) according to claim 1, wherein the fuel is ammonia.
5. Volumetric motive machine (10, 20, 30, 40) according to claim 1, wherein the fuel comprises ammonia added with hydrogen and/or hydrocarbons or other fuels which include carbon in their composition.
6. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, in which the fuel is present in excess with respect to the stoichiometric value of the oxidation reaction.
7. Volumetric motive machine (10, 20, 30, 40) according to claim 1, wherein the fuel comprises hydrocarbons or other fuels which include carbon in their composition.
8. Volumetric motive machine (10, 20, 30, 40) according to claim 7, in which the hydrocarbons consist entirely or in part of methylcyclohexane (MCH).
9. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, in which the mechanical power delivered by the machine feeds an electric generator.
10. Volumetric motive machine (10, 20, 30, 40) according to any of claims 1 to 8, in which the mechanical power delivered by the machine feeds a propulsion line of a motor vehicle.
11. Volumetric motive machine (10, 20, 30, 40) according to claim 10, wherein said motor vehicle is a watercraft, a ship or other water vehicle.
12. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, in which said at least one supply duct (1) and at least one exhaust duct (12) are connected to each other in order to optimize the corresponding fuel and exhaust gases.
13. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, comprising a further injector configured to inject into the casing (8, 23), during the compression phase, at least part of the fuels.
14. Volumetric motive machine (10, 40) according to any of the preceding claims, in which the operating sequence substantially equivalent to a Diesel cycle is a four-stroke cycle and the inlet openings (3) and the exhaust openings (4) are controlled by controlled valves.
15. Volumetric motive machine (20, 30) according to any of claims 1 to 13, wherein the operating sequence substantially equivalent to a Diesel cycle is a two-stroke cycle.
16. Volumetric motive machine (30) according to claim 15, wherein the discharge openings (31) are controlled by controlled valves.
17. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, further comprising a heat exchange system (13) for recovering the heat of the exhaust gases passing through the exhaust duct
(12).
18. Volumetric motive machine (10, 20, 30, 40) according to claim 17, wherein the heat exchange system (13) is an organic Rankine cycle (ORC) system.
19. Volumetric motive machine (10, 20, 30, 40) according to claim 18, in which the organic Rankine cycle (ORC) operates on several temperature levels (42) or with cascade cycles.
20. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, further comprising a separator (16) of the exhaust gas condensate.
21. Volumetric motive machine (10, 20, 30, 40) according to claim 20, wherein the separator (16) is provided with a vent (17) to remove non condensable or other aeriform gases.
22. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, further comprising a recirculation duct (19) of the residual gas downstream of the separator (16).
23. Volumetric motive machine (10, 20, 30, 40) according to claim 22, in which an operating machine (19a) is allocated along the recirculation duct (19) to compress the recirculated fluid starting from the separator (16) to pressures higher than the pressure in the inlet duct (1).
24. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, in which the turbine expander (41) is a multistage axial turbine.
25. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, in which the pump (6) supplies the injection system (200) comprising a common line (205) from which individual injectors (201) of the oxygen depart, wherein a heat exchanger (203) is interposed between the common line (205) which transfers heat to the oxygen flow coming from the pump (6).
26. Volumetric motive machine (10, 20, 30, 40) according to claim 25, wherein the injection system (200) comprises a return pipe (206) upstream of the heat exchanger (200), a compressor (204) and a breather (202).
27. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, provided with a crankcase pressurized with inert gas.
28. Volumetric motive machine (10, 20, 30, 40) according to claim 27, wherein said inert gas is argon.
29. Volumetric motive machine (10, 20, 30, 40) according to any of the preceding claims, further comprising a system (70) for the production of hydrogen in the gaseous phase and the compressed oxygen in the liquid phase starting from hydrogen in the liquid phase and oxygen in the gaseous phase, said system being equipped with:
- a first tank (71) containing gaseous oxygen,
- a second tank (72) containing liquid hydrogen, - a pump (73) that moves the hydrogen,
- a heat exchanger (74) between hydrogen and oxygen which, due to the effect of the heat exchange, causes the liquefaction of oxygen and the gasification of hydrogen,
- a third tank (75) which contains oxygen in the liquid phase. 30. Volumetric motive machine (10, 20,
30, 40) according to claim 29, wherein the system (70) comprises a further heat exchanger (76) for further heating of the hydrogen and a turbine (77) for the expansion of gaseous hydrogen and to obtain mechanical/electrical power.
31. Volumetric motive machine (10, 20, 30, 40) according to any of claims 1 to 28, further comprising a system (80) for the production of hydrogen in the gaseous phase and the compressed oxygen in the liquid phase starting from hydrogen in liquid phase and from air, said plant being equipped with:
- a source of compressed and purified air (81), - a tank (72) containing liquid hydrogen,
- a pump (73) that moves the hydrogen,
- a single heat exchanger (82) in which the air is cooled in counter-current both by hydrogen and by the return flow, substantially formed by nitrogen, which comes from a nitrogen/oxygen separator (83).
32. Volumetric motive machine (10, 20, 30, 40) according to claim 31, in which the system (80) comprises, in replacement of the single heat exchanger (82), at least two separate heat exchangers, a first heat exchanger (84) for the air/nitrogen return flow heat exchange and a second heat exchanger (85) for the air/hydrogen heat exchange.
33. Method for the production of hydrogen in the gaseous phase, as a fuel, and compressed oxygen in the liquid phase, as an oxidizer, the method being implemented in a volumetric driving machine (10, 20, 30, 40) according to claim 30, the method being characterized by the following steps: - storing liquid hydrogen and pressurized gaseous oxygen in containers accessible to the volumetric driving machine,
- substantially counter-current heat-exchanging between hydrogen to be gasified and oxygen to be liquefied,
- expanding hydrogen in the gas phase in the turbine.
34. Method for the production of hydrogen in the gaseous phase, as a fuel, and compressed oxygen in the liquid phase, as an oxidizing agent, the method being implemented in a volumetric driving machine (10, 20, 30, 40) according to claim 31 or 32, the method being characterized by the following steps:
- supplying liquid hydrogen and air purified from water and particulates,
- substantially counter-current heat-exchanging between hydrogen to be gasified and air,
- separating the nitrogen fraction, which has remained gaseous, from the condensed oxygen,
- heat-exchanging between nitrogen fraction and air.
35. Electrical grid (100) provided with renewable energy sources and electric users, including at least:
- an electrolyser (110), for the production of hydrogen and oxygen in the gaseous phase,
- fuel cells (120), for the supply of electrical power to the grid (100), e
- a volumetric motive machine (10, 20, 30, 40), according to any of the claims from 1 to 32, in electrical connection with the network (100) and configured to supply electrical power subservient to the absorption of the peaks of demand for electrical power required by the network (100).
36. Electrical grid (100) according to the preceding claim, further comprising:
- a first tank (140) containing liquid hydrogen and a second tank (150) containing liquid oxygen, - a first machine (160) and a second machine (170) for liquefaction or regasification, respectively, of hydrogen and oxygen, and
- a power supply comprising a mixture of natural gas and hydrogen.
PCT/IB2022/051151 2021-02-24 2022-02-09 Internal combustion engine powered with hydrogen and liquid oxygen WO2022180471A1 (en)

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IT102021000004295A IT202100004295A1 (en) 2021-02-24 2021-02-24 VOLUMETRIC DRIVE MACHINE FUEL WITH HYDROGEN AND LIQUID OXYGEN

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Citations (8)

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Publication number Priority date Publication date Assignee Title
GB398367A (en) * 1932-11-22 1933-09-14 Fritz Von Opel Improvements in and relating to internal combustion engines and methods of operating the same
US4112875A (en) * 1976-08-27 1978-09-12 Nasa Hydrogen-fueled engine
US20080223332A1 (en) * 2007-03-16 2008-09-18 Maro Performance Group, Llc Advanced internal combustion engine
EP2383450A1 (en) * 2010-04-29 2011-11-02 Messer Group GmbH Method for operating a combustion engine and combustion engine
EP2532856A1 (en) * 2010-02-03 2012-12-12 Toyota Jidosha Kabushiki Kaisha Working-gas-circulation-type engine
EP2860373A1 (en) * 2012-06-06 2015-04-15 Toyota Jidosha Kabushiki Kaisha Working gas circulation type engine
EP3163064A1 (en) * 2015-10-29 2017-05-03 STMicroelectronics Srl Engine group comprising a mixed fuel engine, and fuel supplying method thereof
DE102019106722A1 (en) * 2019-03-17 2020-09-17 Martin Steiner Internal combustion engine and method for operating this internal combustion engine

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB398367A (en) * 1932-11-22 1933-09-14 Fritz Von Opel Improvements in and relating to internal combustion engines and methods of operating the same
US4112875A (en) * 1976-08-27 1978-09-12 Nasa Hydrogen-fueled engine
US20080223332A1 (en) * 2007-03-16 2008-09-18 Maro Performance Group, Llc Advanced internal combustion engine
EP2532856A1 (en) * 2010-02-03 2012-12-12 Toyota Jidosha Kabushiki Kaisha Working-gas-circulation-type engine
EP2383450A1 (en) * 2010-04-29 2011-11-02 Messer Group GmbH Method for operating a combustion engine and combustion engine
EP2860373A1 (en) * 2012-06-06 2015-04-15 Toyota Jidosha Kabushiki Kaisha Working gas circulation type engine
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