Volumetric booster for gaseous and / or cryogenic fuel with a four-and-a-half-stroke cycle

Abstract

The invention relates to a four-and-a-half-stroke volumetric booster for gaseous and / or cryogenic fuel. The device comprises a volumetric machine associated with a closed and independent transfer chamber (10), intended to receive the residual gases after expansion and to deliver them during the suction and / or compression phases. An internal or external heating system in this chamber increases the pressure and temperature of the outgoing fuel stream. The invention is situated within the fuel supply circuit of a receiver, with the aim of providing it with fuel or a fuel-rich stream under satisfactory pressure and temperature conditions for its proper operation. Figure for the abstract: [Fig 1]

Description

Title of the invention: Volumetric booster for gaseous and / or cryogenic fuel with a four and a half stroke cycle

[0001] In the context of the use of gaseous and / or cryogenic fuels such as hydrogen to power engines or fuel cells, or more generally a heating system, one of the difficulties consists of preparing the fuel fluid by giving it the necessary and compatible pressure and temperature conditions for its injection and use.

[0002] The "Four and a half stroke cycle gaseous and / or cryogenic fuel volumetric booster" is therefore located on the fuel supply circuit of a receiver in order to provide it with fuel or a fuel-rich flow under satisfactory pressure and temperature conditions for its proper operation. By receiver, here and below, we mean: all thermal engines, internal combustion, external combustion, fuel cells, but also all fuel combustion heating systems in general and also fuel distribution systems in service stations for filling machines of all types. For better understanding and for simplification, during the description below, the word receiver is often replaced by analogy with the word engine.

[0003] Direct liquid injection at very low temperatures is often not compatible with the technologies and processes of engines, boilers or fuel cells.

[0004] Furthermore, it is difficult to maintain a liquid cryogenic fluid around the hot parts of a heat engine. As all or part of the fuel evaporates, the management of multiphase injections (liquid and gas in the same pipe) becomes complex to implement and impossible to manage, particularly when the flow rates, pressures and temperatures can have large amplitudes.

[0005] Furthermore, the cryogenic lines which would bring the cryogenic fluid to the receiver are complex and expensive, and for many applications the risk of the presence of frost along these lines is prohibited.

[0006] It is therefore particularly advantageous, even in the case of liquid fuel storage, to inject said fuel in the gaseous phase into the engines and / or fuel cells. Furthermore, in the context of direct injection thermal engines and in turbomachines, the injection pressures in the chambers require high pressures.

[0007] Nevertheless, two problems persist with the totally gaseous distribution of liquid hydrogen: - Even under pressure, the diameter of the pipes is important. - The evaporation in the tank of the entire consumption of liquid hydrogen results in very high cooling power during high consumption phases, which can lead to overcooling of the liquid hydrogen and even the risk of solidification, very often requiring the counterproductive use of heaters within the tanks themselves.

[0008] The patent “Cryogenic generator of pressurized gaseous hydrogen - cryogenic booster” No. FR3136260 - 08 / 12 / 2023 (BOPI 2023-49) describes a 2-stroke or 4-stroke volumetric machine capable of simultaneously compressing gaseous hydrogen and liquid hydrogen using the supercompression power of the evaporation of the latter or an internal heat input by combustion of a small part of the hydrogen, or an external heat input of the glow plug type or via a heat transfer fluid.

[0009] The present invention "Volumetric booster for gaseous and / or cryogenic fuel with a four and a half stroke cycle" consists of completing and developing the preceding device by modifying the thermodynamic cycle of a 4-stroke compressor and adding to it a transfer phase in an independent closed chamber. This chamber is called the transfer chamber (10). It is intended to receive the residual gases after expansion during phase 4 called "Transfer" in a traditional 4-stroke engine and to restore them during phase 2 called "Compression" and / or 2 called compression. These transfer phases of loading and unloading of said transfer chamber (10) take place in parallel with the other 4 conventional strokes, hence the name four and a half stroke.

[0010] The "Four and a half stroke cycle gaseous and / or cryogenic fuel volumetric booster", hereinafter referred to as Booster, is therefore located on the fuel supply circuit of a potential receiver, with the aim of providing it, via the outlet channel (15), with a flow (flow rate) of fuel or a flow (flow rate) of a fuel-rich fluid under satisfactory pressure and temperature conditions for its proper operation. By potential receiver, here is meant all thermal engines, internal combustion, external combustion, fuel cells, but also all fuel combustion heating systems in general and fuel distribution systems in service stations. This device is particularly suitable for the supply and distribution of gaseous and / or cryogenic hydrogen.

[0011] When the Supercharger has an external heat supply system, the transfer chamber (10) has a heating system either of the electrical type, for example one or more preheating plugs or a high-frequency heating system, or close to a heat supply system via channels transporting a heat transfer fluid, for example from the fuel cell or the cooling circuit of the engine(s), or more simply a heat exchange system with the external environment (external fins).

[0012] When the Supercharger has an internal heat supply system, i.e. the combustion of a small part of the compressed hydrogen, said transfer chamber has an air or oxygen supply system, for example a valve or an injector, and an ignition system, for example a spark plug.

[0013] In certain applications, when the temperature in the transfer chamber is too high, an external cooling system may be provided around said transfer chamber to stabilize its temperature.

[0014] [Fig.l] schematically shows a volumetric machine for overpressurizing a cryogenic fuel composed of a part of gaseous hydrogen (GH2) and a part of liquid hydrogen (LH2) comprising a piston (1) - connecting rod (2) - crankshaft (3) assembly, a cylinder (4), an inlet valve for gaseous hydrogen GH2 (5) on the inlet channel (14), an air inlet valve (6), a liquid hydrogen injection system (7), a spark plug (8), both an inlet and an exhaust valve (9) of the transfer chamber (10) and an exhaust valve (13) on the outlet channel (15) in the direction of supplying the engine(s) and / or the fuel cell(s). The channel for a heat transfer fluid is shown at (12).Its role can be twofold, on the one hand providing external heating power within the transfer chamber (10), but also cooling power for said transfer chamber (10) during combustion phases which can occasionally lead to very high temperatures.

[0015] The upper part of the cylinder above the piston at TDC (top dead center) is called the main chamber (16) and the part below the cylinder is called the crankcase (11). When the piston is located at the bottom of its stroke, it is considered at BDC (bottom dead center).

[0016] The crankshaft of the supercharger is driven either by an independent motor, for example an electric motor, or directly by the shaft of the motor that it powers, in direct drive or via a reduction gear device.

[0017] The theoretical thermodynamic cycle of the booster is as follows:

[0018] As a preliminary it should be considered that in the cycle if a valve is not specifically described as open, it is considered closed and therefore watertight.

[0019] PHASE 1 (Suction): The piston (1) at TDC descends to BDC, creating a reduction in pressure in the cylinder (4). During this descent, the intake valve GH2 (5) opens, allowing gaseous hydrogen to enter from a tank. This gaseous hydrogen may have been pressurized beforehand by a supercharging system. A certain quantity of liquid hydrogen LH2 is injected, or not, through the injector (7). The liquid hydrogen vaporizes in the gaseous hydrogen GH2 while cooling it. If the proportion of liquid hydrogen is too high compared to the quantity of gaseous hydrogen, all or part of this liquid hydrogen can be injected during PHASE 2. In parallel, the air-hydrogen mixture formed in the previous cycle in the transfer chamber (10) is ignited by the spark plug (8). The pressure and temperature increase sharply in the transfer chamber (10).If the gas temperature in the cylinder (4) is too low, for example if the initial temperature of the GH2 is too low and / or if too much LH2 is injected, it is possible to anticipate the opening of the exhaust valve (9) of the transfer chamber (10) from this phase.

[0020] PHASE 2 (Compression): The piston (1) at BDC rises towards TDC and compresses the contents of the cylinder (4). The exhaust valve (9) of the transfer chamber (10) is opened and the high pressure and high temperature mixture flows into the cylinder (4) causing a rapid and sharp rise in pressure and temperature of the hydrogen gas above the cylinder.

[0021] PHASE 3 (Discharge-Expansion): The piston (1) is at TDC, the exhaust valve (13) is opened and the gaseous hydrogen mixture GH2 with a little water H2O and nitrogen N2 is directed (discharge) towards the engine(s) and / or the fuel cell(s) via the outlet channel (15) either directly or via an intermediate reservoir called a buffer. The cylinder (4) empties and the pressure decreases. When the pressure in the cylinder (4) falls below that of the buffer or a set value imposed at the engine inlet, the exhaust valve (13) closes. The piston continues its descent towards the TDC. The exhaust valve (9) is still open, which allows the transfer chamber (10) to be discharged. When the piston (1) reaches BDC, the exhaust valve (9) is closed and the air inlet valve (6) is opened to fill the transfer chamber (10) with a certain quantity of air.The air can come from the compressor stages of a turbomachine, from the cylinders of a reciprocating engine, from any supercharging system, directly linked to the engine or independent, or even from a pressurized air or oxygen cylinder. The air intake valve (6) is then closed.

[0022] PHASE 4 (Transfer): The piston (1) at the BDC rises towards the TDC, recompressing the volume located above it. During its rise, when the pressure in the cylinder (4) is higher than that in the transfer chamber (10), the inlet valve (9) of the transfer chamber (10). The transfer chamber fills with the very hydrogen-rich mixture and increases in pressure as the piston (1) rises towards TDC. When the piston (1) reaches TDC, the inlet valve (9) is closed and the transfer chamber is ready for further combustion during the next phase.

[0023] The cycle is ready to start again with phase 1 (Intake) when the piston (1) descends.

[0024] The various valves can be duplicated or multiplied. They can be actuated by mechanical systems, for example cams, or by pneumatic, hydraulic, electrical or other controls.

[0025] The injector (7) can be supplied either directly by the cryogenic tank or via a cryogenic pump. It can be controlled by a regulator, for example a solenoid valve, which defines the quantity of liquid hydrogen injected.

[0026] The cycle can be controlled and monitored: by mechanisms and sensors for controlling the rotation speed and the time, duration and quantity of liquid hydrogen injected; and / or mechanisms for controlling the opening time, closing time and profile of the lift of the various valves; and / or pressure and temperature sensors in the main chamber (16), in the transfer chamber (10), in the intake (14) or outlet (15) pipes, in the “buffer” tank(s). Similarly, the regulation of the cycle can exchange and interface with the regulation and supervision systems of the engines, the fuel cells, the fuel storage and distribution circuits and the general supervision of the installations or machines.

[0027] For simplification, the figure and the description presented represent a single-cylinder system, but the volumetric machine can also contain several cylinders in line or flat or in V or in opposition or even in star or any other configuration. Similarly, to stabilize the rotation speed of the volumetric machine, a flywheel can be associated with it. The volumetric machine can also be of the rotary type, for example Wankel.

[0028] A vane pump for supplying the gaseous hydrogen inlet pipe is a particularly interesting solution, because in addition to pressurizing the gaseous hydrogen at the inlet into the machine. It has a high suction capacity by creating a beneficial depression upstream for the evaporation of liquid hydrogen in the cryogenic tank, for example as described in the patent "Hydrogen storage and distribution device for aircraft" No. FR3135253 - 10 / 11 / 2023 (BOPI 2023-45). Furthermore, this same patent describes, in addition to a compressor at the outlet of the cryogenic tank, a pressurized tank downstream of the compressor which corresponds to the "buffer" described above.

[0029] On the liquid hydrogen injection side, if the pressure in the tank is not sufficient to inject the LH2 into the chamber, the device may require the addition of a pump to the circuit.

[0030] In certain configurations, it may be advisable to integrate the LH2 injector not for direct injection into the cylinder (4), but into the supply pipe (14) for the gaseous hydrogen GH2 upstream of the cylinder (4).

[0031] Similarly, in the case of an exclusively gaseous upstream hydrogen storage tank or in the case of a cryogenic storage tank, but whose evaporation flow rate is sufficient to cover the consumption of the engine(s) and / or the fuel cell(s), it will be possible to eliminate the injection of liquid hydrogen and therefore the associated injector.

[0032] The device associated with an internal heating system, therefore with combustion of a portion of the treated hydrogen, is very efficient, but has the disadvantage of the presence of water and possibly nitrogen in the fuel flow to the engine(s) and / or the fuel cell(s). If necessary, the system may be supplemented by a water trap, for example in the buffer tank. When the receiving system requires a good level of fuel purity, for example in the case of the fuel cell, external electric or heat transfer fluid heating will be preferred, which has the advantage of not inserting water, nitrogen, or impurities present in the air into the fuel flow.

[0033] Similarly, to improve the operation of the device, it may be advantageous to add one or more heat exchangers to the intake pipe (14) in order either to improve the filling or to increase the intake temperature of the GH2 and allow more LH2 to be injected. One or more exchangers may also be added either to the outlet pipe (15) and / or the so-called “buffer” tank, either to heat the fuel before its injection into the engine, or to cool it if the adjustment of the booster results in a fuel flow that is too hot to be injected into the engine.

[0034] One of the design difficulties of the device presented consists of finding technological solutions for sealing between the piston (1) and the cylinder (4) and particularly in the context of operation with hydrogen. The patent “Cryogenic generator of pressurized gaseous hydrogen - cryogenic booster” No. FR3136260 - 08 / 12 / 2023 (BOPI 2023-49) addressed this problem with a 2-stroke cycle which made it possible to have hydrogen on both sides of the piston.

[0035] It is possible to take up this technological solution by using the volume under the piston called the casing (11): - Either as storage capacity of the hydrogen gas intake before transfer to the intake pipe (14) and the intake valve (5); - Either by using it as a storage capacity after the exhaust valve and connecting it with the outlet channel (15). The casing then plays the role of a “buffer” reservoir.

[0036] The rules of thermodynamics dictate that in a volumetric machine and for a given compression ratio, the lower the gas intake temperature, the lower the specific power consumed and the higher the flow rate. In the particular case of hydrogen, gaseous dihydrogen is a mixture of two types of isomeric molecules. From its boiling point up to a temperature of 300K, hydrogen gradually passes from a concentration of almost 100% parahydrogen to 75% orthohydrogen. This transformation, naturally quite slow, is endothermic. In an isolated, quasi-adiabatic system, this transformation, if accelerated for example with a catalyst, makes it possible to lower the temperature of the gaseous dihydrogen and therefore to reduce the specific power of the supercharger and to increase its flow rate for a given cylinder capacity.Therefore, a sensible solution is to deposit either in the intake channel (14) or in the crankcase (11) if it is used as storage for the intake gas, a catalyst, for example iron hydroxide (Fe2 03) in order to accelerate the transformation from para to orthohydrogen and to cool the GH2 before its admission into the cylinder.

[0037] The booster device is equipped with sensors capable of monitoring and / or controlling the compression cycle and / or communicating with the tank(s) and / or with the installations which receive the flow exiting the booster.

[0038] Upon reading the above description, it is obvious that the present general device "Volumetric booster for gaseous and / or cryogenic fuel with a four and a half stroke cycle" could use a fluid other than hydrogen, such as for example LNG, LPG or others, and / or the air could be replaced by pure oxygen. Similarly, the use of the present device could be extended to heating installations and to any application in general, which requires a significant increase in the pressure of a gas or a fluid in the evaporation phase. Finally, the device could also be used in the context of the distribution of fuel and more generally of cryogenic fluids, for example for the distribution of gaseous hydrogen from a storage of liquid hydrogen in service stations.

[0039] The device as a whole may be used in particular to power engines (reciprocating engines, rotary engines, turboshaft engines, turboprop engines, turbojets, ramjets, rocket engines or others) and / or fuel cells in the context of propulsion or auxiliary power units of air, space, land, naval or submarine vehicles. In this case, said device may be managed and controlled by management and regulation systems independent or not, including the engine(s) and / or the fuel cell(s) and / or the hydrogen storage and distribution device(s).

[0040] Device for compressing and distributing a gaseous and / or cryogenic fuel to supply one or more engines and / or one or more fuel cells and / or one or more heating systems and / or one or more fuel distribution systems in service stations, comprising:

[0041] at least one volumetric compressor,

[0042] associated with at least one closed and independent transfer chamber (10),

[0043] characterized by the fact that this transfer chamber is intended to receive the residual gases after expansion and to restore them during the suction and / or compression phases.

[0044] Device, characterized in that the main cycle of the compressor is carried out with gaseous fuel and that liquid fuel is injected during the suction and / or compression phases into the cylinder (4) by the injector (7).

[0045] Device, characterized in that the liquid fuel injector (7) is located in the suction channel (14) downstream of the inlet into the cylinder (4).

[0046] Device, characterized in that the volumetric compressor is composed of several cylinders.

[0047] Device, characterized in that the volumetric compressor can also be of the rotary type.

[0048] Device, characterized in that there is an external heating system in the transfer chamber (10) capable of increasing the pressure and temperature in the transfer chamber (10).

[0049] Device, characterized in that there is an internal combustion system in the transfer chamber (10), comprising an air (6) or oxygen supply system and an ignition system (8), capable of increasing the pressure and temperature in the transfer chamber (10).

[0050] Device, characterized in that there is a means of supercharging the gaseous hydrogen at the inlet of the compressor, either by another compressor or by pressurizing the source tank.

[0051] Device, characterized in that the hydrogen gas uses the casing (11) as a storage capacity for the admission of the hydrogen gas before transfer to the admission channel (14) and the admission valve (5).

[0052] Device, characterized in that the casing (11) is used as a storage capacity (buffer) after the exhaust valve and by connecting it with the outlet channel (15).

[0053] Device, applied specifically to cryogenic hydrogen, characterized in that there is a process for accelerating the transformation of parahydrogen into orthohydrogen upstream of the intake valve (5).

[0054] Device, characterized in that the booster is equipped with sensors capable of monitoring and / or controlling the compression cycle and / or communicating with the upstream reservoir(s) and / or with the installations which receive the flow leaving the booster.

[0055] Use of a device for powering either the engines and / or fuel cells in the context of air, space, land, naval or underwater vehicles, or in the context of heating and / or refrigeration installations, or in the context of the distribution of cryogenic fluids.

Claims

Claims

1. Device for compressing and distributing a gaseous and / or cryogenic fuel to supply one or more engines and / or one or more fuel cells and / or one or more heating systems and / or one or more fuel distribution systems in service stations, comprising: - at least one volumetric compressor operating according to a 4-stroke cycle, - said compressor being associated with at least one closed and independent transfer chamber (10), characterized in that this transfer chamber is intended to receive the fuel-rich fluid after an expansion phase in the compressor and to restore it during suction and / or compression phases in the compressor.

2. Device according to claim 1, characterized in that the main cycle of the compressor is carried out with gaseous fuel and that liquid fuel is injected during the suction and / or compression phases into a cylinder (4) by an injector (7).

3. Device according to claim 2, characterized in that the liquid fuel injector (7) is located in a supply pipe (14) for gaseous hydrogen GH2 upstream of the cylinder (4)

4. Device according to claims 1 and 3, characterized in that the volumetric compressor is composed of several cylinders.

5. Device according to one of claims 1 to 4, characterized in that the volumetric compressor can also be of the rotary type.

6. Device according to one of claims 1 to 5, characterized in that there is an external heating system in the transfer chamber (10) capable of increasing the pressure and temperature in the transfer chamber (10).

7. 7 Device according to one of claims 1 to 6, characterized in that there is an internal combustion system in the transfer chamber (10), comprising an air (6) or oxygen supply system and an ignition system (8), capable of increasing the pressure and temperature in the transfer chamber (10).

8. Device according to one of claims 1 to 7, characterized in that there is a means for supercharging the gaseous hydrogen to the compressor inlet, either by another compressor or by pressurization of the source tank.

9. Device according to one of claims 1 to 8, characterized in that the hydrogen gas uses a casing (11) as storage capacity for the intake of the hydrogen gas before transfer to the intake channel (14) and the intake valve (5).

10. Device according to one of claims 1 to 9, characterized in that the housing (11) is used as a storage capacity after the exhaust valve and by connecting it with the outlet channel (15).

11. Device according to one of claims 1 to 10, applied specifically to cryogenic hydrogen, characterized in that there is a means for accelerating the transformation of parahydrogen into orthohydrogen upstream of the intake valve (5).

12. Device according to one of claims 1 to 11, characterized in that a booster is equipped with sensors capable of monitoring and / or controlling the compression cycle and / or communicating with the reservoir(s) and / or with the installations which receive the flow leaving the booster.

13. Use of a device according to one of claims 1 to 12, for powering either the engines and / or the fuel cells in the context of air, space, land, naval or underwater vehicles, or in the context of heating installations, or in the context of the distribution of cryogenic fluids.