NO346132B1

NO346132B1 - Fuel cell powered turbine-less jet engine.

Info

Publication number: NO346132B1
Application number: NO20200940A
Authority: NO
Inventors: Mohamad Mustafa
Original assignee: Univ I Tromsoe Norges Arktiske Univ
Priority date: 2020-08-28
Filing date: 2020-08-28
Publication date: 2022-03-14
Also published as: WO2022043293A1; NO20200940A1

Description

FIELD OF THE INVENTION

The present invention relates to a jet engine comprising a combustor and a fuel cell.

BACKGROUND AND PRIOR ART

Conventional jet engines are combustion engines relying on fossil fuels, hence producing harmful emissions and have overall low efficiency due to Carnot cycle limitations. In a conventional gas turbine engine, ambient air is compressed to a higher pressure by the compressor and forced into the combustor. Air in the combustor is mixed with fuel and combusted, hence achieve an increase in temperature and volume. The resulting air mix, typically at a temperature of around 2000<o>C, is guided to the turbine and causes the latter to rotate.

The rotational power from the turbine is transmitted to the gas compressor through a relatively long drive shaft. In order to start such conventional jet engines, an external power unit starts the compressor and drives the turbine to kick off the cycle of operation of the engine.

Consequently, a part of the energy of the heated air is used to drive the turbine and thereby the compressor. The remaining energy in the air is used to generate the desired thrust at the nozzle which pushes the engine forward.

In addition to release of harmful emissions and low efficiency, the long drive shaft, the turbine and the external engine all contributes to complexity and weight.

Fossil fuel free jet engines are known in the field. Patent publication CN110608108A describes a turbojet engine having a fuel cell integrated. A DC motor drives a compressor through a connection shaft, causing a partial oxidation behind the DC motor and the fuel cell. The fuel cell is used to generate electricity to drive the DC motor, which then drives the compressor through a shaft connection. Another example of a fossil fuel free jet engine is described in US9897041B2, wherein the jet engine comprises inter alia a fuel cell arrangement, a fan and an electric motor. Yet another example of a fossil fuel free jet engine is described in US8394552B2. For all technical solutions, the fuel cell is used to supply power to electic driven components.

EP 0967676 A1 discloses an invention that relates to fuel cells used in conjunction with jet engines. In this document the fuel cell is generating electricity which eliminates moving parts from the electricity generation process and allows the components associated with electricity generation to be disposed within the housing of the engine.

US 2012304645 A1 describes use of a fuel cell for powering all the components of a jet engine, but especially heating elements used to heat the air moving through the engine, rather than burning jet fuel.

JP 2017 describes a jet engine comprising: a high-pressure compressor which compresses gas; a combustor which burns fuel by the gas that has been compressed; and a high-pressure turbine which drives the high-pressure compressor with combustion gas from the first combustor serving as a driving source. A flow channel is provided to take out, to the outside, part of the gas supplied to the combustor 32. A fuel cell system comprises: a fuel cell; and a compressor which introduces the gas as a working fluid for the fuel cell 42 via the flow channel so as to supply the working fluid to an introduction port on an air electrode side of the fuel cell, with the working fluid controlled to be at a desired temperature.

US 2009293494 A1 discloses a drive device for an aircraft comprising a gas turbine apparatus for generating a first drive energy and electric motor for generating a second drive energy. The gas turbine apparatus and the electric motor are set up in such a way that the drive unit may be provided with at least one of the first drive energy and the second drive energy. The drive unit is set up to generate propulsion using at least one of the first drive energy and the second drive energy.

US 2005266287 A1 relates to a device for producing water on board of an airplane by means of one or several fuel cells. The water producing device is embodied in the form of one or several high temperature fuel cells and entirely or partially integrated into a jet power unit of the airplane in such a way that the combustion chambers of said jet power unit of the airplane are entirely or partially substituted by said high temperature fuel cells. The aim is to develop a combination of fuel cells and a gas turbine which operates exclusively with atmospheric hydrogen and oxygen and is embodied in the form of a jet power unit and/or an auxiliary jet power unit (on-board auxiliary power unit: APU) used for producing compressed air for a cabin and a power supply. For this purpose, said high temperature fuel cells are fed with pure hydrogen on an anode side and with air on a cathode side. The combustion chambers are fed with an air-hydrogen mixture, enabling at least the hydrogen supply to be adjusted or completely shut off.

US 6641084 B1 describes an auxiliary power unit (APU) for an aircraft utilizing solid oxide fuel cells for providing electrical power. The solid oxide electrolytes of the fuel cells allow for reformed fuel to provide a catalyst for oxygen migration. The auxiliary power unit, utilizing solid oxide fuel cells, can also power systems of the aircraft to produce water for use on the aircraft. Waste exhaust energy may be captured from the APU by a power recovery turbine which drives a compressor to provide aircraft cabin air under increased pressure to the fuel cell, thereby increasing system efficiency. The APU may provide all of the electricity to the aircraft allowing for more efficient aircraft engine design and a decrease in aircraft engine size. Furthermore, the fuel cell APU can reduce airport ramp noise and exhaust emissions.

US 2010293959 A1 describes a power supply device or system for aeronautics, having a hydrocarbon supply for supplying an engine with hydrocarbon fuel and a hydrogen supply having a fuel reformer for producing hydrogen from hydrocarbon fuel from said hydrocarbon supply. The hydrogen supply is connected to a hydrogen-powered fuel cell for producing electric power and to a hydrogen injecting system for injection of hydrogen into a combustion chamber of the engine. Further, the patent publication describes an aircraft having an engine that can be supplied by that power supplying device or system, and a method for operating said engine.

US 2003075643 A1 describes an electrically powered aircraft having fuel cells as at least a partial source of electrical energy. In many instances the electrical energy powers an electric motor used to propel the aircraft. In some instances, the electric output from the fuel cell would be augmented by power from special high power "surge" batteries for critical takeoff and climbing, where the maximum electric power is required. In preferred embodiments, such fuel cell powered aircraft will supply oxygen to the fuel cell either from a container of oxygen carried on board the aircraft, or from a ram scoop which directs air through which the aircraft is moving to the fuel cell.

An objective of the present invention is therefore to provide a jet engine that at least mitigate the disadvantages of the conventional jet engines.

In particular, it is an objective of the invention to provide a jet engine where harmful emission gases are reduced or eliminated.

Another objective of the invention is to provide a jet engine, which has a higher operational efficiency compared to conventional jet engines.

Yet another objective is to provide a jet engine, which is less complex and of lower weight compared to conventional jet engines.

SUMMARY OF THE INVENTION

The invention is set forth in the independent claims and the dependent claims describe certain optional features of the invention.

In particular, the invention concerns a jet-engine comprising an outer casing having an opening end for allowing inlet gas to enter therein, a combustor system comprising a combustor container enclosing a combustor chamber, a hot gas combustor inlet for allowing gas to enter within the combustor chamber and a fuel combustor inlet for allowing fuel to enter within the combustor chamber. A first end of the combustor container is arranged in fluid communication with an end of the outer casing opposite its opening end.

The jet engine further comprises a fuel source in fluid communication with the fuel combustor inlet, a nozzle configured to exhaust jet flow gas out of the jet-engine at one side and arranged in fluid communication with the combustion chamber at an opposite side and a cold gas outlet for allowing gas to exhaust from the outer casing.

The jet engine also includes a fuel cell system, a cold gas conduit and a hot gas conduit system. The fuel cell system comprises a fuel cell, at least one fuel and reaction gas inlet for allowing fuel and reaction gas to enter into the fuel cell, a cold gas inlet for allowing gas to enter into the fuel cell and a hot gas outlet for allowing gas to exhaust out of the fuel cell. The cold gas conduit is set in fluid communication between the cold gas outlet of the gas compressor and the cold gas inlet of the fuel cell system. Further, the hot gas conduit system is set in fluid communication between the hot gas outlet of the fuel cell system and the hot gas combustor inlet of the combustor system. The fuel cell in this configuration acts as a heat exchanger in which heat is added to the compressed air prior to entering the combustion chamber to increase its temperature and volume. By allowing hot gas from the fuel cell and fuel from the fuel source to enter into the combustor chamber, a jet flow will be exhausted out of the nozzle, thereby creating a reaction force opposite of the jet flow direction. This in turn will create the desired thrust propelling for example an aircraft. To avoid back-flow into the volume set by the outer casing and/or the fuel cell, the pressure within at least part of the outer casing, for example within an inner casing inside the outer casing, should be equal to the pressure at the hot gas outlet of the fuel cell. Further, the pressure in the combustor chamber set by inter alia the gas from the fuel cell and the fuel reservoir should be equal or lower to the gas pressure at the hot gas outlet.

The fuel and reaction gas inlet(s) preferably comprise(s) one inlet adapted for receiving the fuel from a fuel reservoir (typically hydrogen and/or a hydrocarbonbased compound) and one inlet adapted for receiving the reaction gas from a reaction gas reservoir (typically oxygen and/or ambient air). The reaction gas reservoir may comprise a reaction gas outlet and further that the jet engine comprises a reaction gas conduit set in fluid communication between the reaction gas outlet and the reaction gas inlet of the fuel cell system. Further, the fuel reservoir may comprise a fuel outlet and further that the jet engine comprises a fuel conduit set in fluid communication between the fuel outlet and fuel inlet of the fuel cell system.

In an exemplary configuration the jet engine preferably also comprises gas compressor means in order to force more combustion gas into the combustor chamber. The gas compressor means includes a gas container, a gas compression device configured to compress a gas within the gas container to an elevated pressure P70 and a temperature T70, wherein the cold gas outlet is in fluid communication with the gas container. As an exemplary configuration, such gas compressor is placed within the outer casing, for example within an inner casing arranged at the radial center inside the outer casing.

In another exemplary configuration the jet engine further comprises a fuel regulator in fluid communication with the fuel reservoir, a combustor conduit in fluid communication between the fuel regulator and the combustor chamber, for example via the hot gas combustor inlet(s) and/or via a separate fuel inlet, and a regulator fuel conduit in fluid communication between the fuel regulator and the fuel and reaction gas inlet(s) of the fuel cell system, for example through a dedicated fuel inlet.

In yet another exemplary configuration the hot gas conduit system comprises a dehumidifier for dehumidification of the gas exhausted from the hot gas outlet of the fuel cell system. Such dehumidifier is an advantage since superheated water particles can exist in the working fluid that can cause damage to the jet engine components and reduce efficiency of the combustion.

In yet another exemplary configuration the hot gas conduit system comprises a gas mixer for mixing of gases exhausted from the hot gas outlet of the fuel cell system. Said gas mixer is preferably arranged upstream the dehumidifier. Such a gas mixer is advantageous since gases coming out of the fuel cell may be cooling gas (hot compressed air) and reactant gases that have not been consumed in the reaction. These gases come out at different pressures and ratios, and hence should be mixed to regulate their pressure and composition.

In yet another exemplary configuration the fuel cell is configured to generate chemical energy from a chemical reaction between the fuel and the reaction gas when entering into the fuel cell and to produce electric power from the generated chemical energy, and wherein the jet engine further comprises a fuel cell power line extending between the fuel cell and the gas compression device(s) for providing the gas compression device(s) with electric power, for example via an electric motor. In general, the electrical output of the fuel cell may be used to drive all electrical components of the jet engine, not only gas compressors, but also any other electrical equipment such as DC motors.

In yet another exemplary configuration the fuel cell system further comprises a second hot gas outlet for allowing effluent reaction gas to exhaust out of the fuel cell. This second hot gas outlet is (at least indirectly) in fluid communication with the hot gas combustor inlet(s). The fuel cell system may also comprise a third hot gas outlet for allowing effluent fuel to exhaust out of the fuel cell. As for the hot gas outlet and the second hot gas outlet, the third hot gas outlet is in fluid communication with the hot gas combustor inlet(s).

In yet another exemplary configuration the jet engine further comprises a fan arranged within the outer casing such that the outer casing is separated into an upstream chamber configured to allow the inlet gas/air to enter therein and a downstream chamber. An electric motor is rotationally coupled to the fan. The electric motor receives electric power from the fuel cell system and/or an auxiliary electric power source. Further, the electric motor is preferably arranged fully within, or partly within the outer casing, and more preferably downstream the fan.

In yet another exemplary configuration the jet engine further comprises an inner casing separating the downstream chamber into an outer chamber and an inner chamber arranged coaxially within the outer chamber. The inner chamber is in fluid communication with the first end of the combustor container. Note that ‘coaxially’ is relative to the direction of the thrust of the jet engine and the flow of inlet gas. The above-mentioned gas compressor and the electric motor are preferably arranged within this inner casing. Furthermore, the electric motor may be configured to drive both the fan and the gas compressor. In the latter exemplary configuration, the compressor may be placed between the electric motor and the fan. Alternatively, the compressor may be placed downstream the electric motor. The fan however (if present) should in both cases be placed upstream the compressor. Also, the jet engine should include a gearbox since the velocity of rotation of the compressor is normally not the same as the velocity of rotation of the fan. (The latter rotation is usually much slower.) If the compressor is within the inner chamber, the cold gas outlet should be in fluid communication with this inner chamber.

In yet another exemplary configuration the compressed gas conduit is in fluid communication with the outer chamber and/or the inner chamber, most preferably only the inner chamber

In yet another exemplary configuration the end of the outer chamber distal to the fan and the upstream / inlet chamber comprises a cold nozzle for release of gas therefrom.

In yet another exemplary configuration the jet engine further comprises a cooling gas source such as ambient air, a cooling gas compressor, a cooling gas source conduit in fluid communication between the cooling gas source and the cooling gas compressor and a cooling gas compressor conduit in fluid communication between the cooling gas compressor and the cold gas inlet of the fuel cell system. The cooling gas compressor comprises a gas compression device configured to compress a gas within the cooling gas compressor.

In yet another exemplary configuration the jet engine further comprises a cooling gas compressor power line extending between the fuel cell and the gas compression device for providing the latter with electric power.

Similar power lines from the fuel cell may also provide electric power to gas compression devices in the reaction gas compressor and/or the fuel compressor.

In yet another exemplary configuration the jet engine further comprises an auxiliary electric power source for providing electric power to the gas compression device of the different gas compressors outside or within the outer casing, and/or the electric motor. For example, an auxiliary electric power line may be extending between the auxiliary electric power source and the external cooling gas compressor.

The purpose of such an auxiliary power supply may be to ensure / facilitate start -up of the jet engine.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings depict alternatives of the present invention and are appended to facilitate the understanding of the invention. However, the features disclosed in the drawings are for illustrative purposes only and shall not be interpreted in a limiting sense.

Fig. 1 is a schematic drawing of a jet engine according to the invention showing its general mode of operation.

Fig. 2 is a schematic drawing of a jet engine according to a first embodiment of the invention, wherein compressed air is guided from a chamber downstream a fan and into a fuel cell.

Fig. 3 is another schematic drawing of a jet engine according to the first embodiment of the invention.

Fig. 4 is yet another schematic drawing of a jet engine according to a first embodiment of the invention, wherein heated gas from the fuel cell is guided into the combustor via a second stage compressor.

Fig. 5 is a schematic drawing of a jet engine according to a second embodiment of the invention, wherein compressed air is guided into a fuel cell from a dedicated cooling gas compressor.

Fig. 6 is another schematic drawing of a jet engine according to the second embodiment of the invention, wherein cooling gas and reaction gas from respective compressors are guided into the fuel cell via an inlet gas splitter.

Fig. 7 is a schematic drawing of a jet engine according to a third embodiment of the invention, wherein the jet engine contains no fan and electric motor.

Fig. 8 is another schematic drawing of a jet engine according the third embodiment of the invention, wherein cooling gas and reaction gas from respective compressors are guided into the fuel cell via an inlet gas splitter.

Fig. 9 is a schematic drawing of a jet engine according to a fourth embodiment of the invention, wherein the jet engine comprises a plurality of nozzle-combustor systems.

DETAILED DESCRIPTION OF THE INVENTION

In the following, different alternatives will be discussed in more detail with reference to the appended drawings. It should be understood, however, that the drawings are not intended to limit the scope of the invention to the subject-matter depicted in the drawings.

Fig. 1 shows a conceptual sketch of the inventive jet engine 1. The jet engine 1 is composed of inter alia one or more gas containers 70 that receive and contain compressed gas, in particular inlet gas/air 12 being sucked in through an opening into the gas container(s) 70 from a surrounding ambience 90. This gas/air having a pressure P70 and a temperature T70 after compression (by use of a gas compression device / compressor 7,45 located inside and/or outside the gas containers 70) is guided from the gas container(s) 70 to a fuel cell 2’ via one or more cold gas outlets 84 of the gas container(s) 70, one or more fluid conduits 22,23 (double line arrow) and one or more cold gas inlets 82 constituting part of a fuel cell system 2’ containing the fuel cell 2.

The fuel cell system 2’ further comprises one or more fuel and reaction gas inlets 85 connected via one or more fuel conduits 20,21 (single line arrow) to one or more fuel reservoirs 15, in particular hydrogen reservoirs, and via one or more reaction gas conduits 22 to one or more reaction gas reservoirs 42, in particular ambient air 90 or an oxygen reservoir. The fuel reservoirs 15 can contain hydrogen rich fuel or any fuel suitable for high temperature fuel cells such as hydrocarbons including jet fuel. In case of the latter, the jet engine 1 may include a carbon capture device to capture the carbon emissions. However, in a more preferred configuration gaseous compressed hydrogen or liquid hydrogen is used since less harmful emissions will be produced.

By introducing a mix of fuel gas (for example hydrogen) and reaction gas (for example oxygen) into the fuel cell 2 to start and maintain the fuel cell’s 2 electrochemical process, and simultaneously letting the compressed gas from the gas container(s) 70 to go through the fuel cell 2, the gas will heat to an elevated temperature T4 being significantly higher than the temperature T70. For example, T4 can be in the range of 1000<o>C, which is a typical operating temperature of a high temperature fuel cell such as Solid oxide fuel cell SOFC. T70 can be room temperature (~25<o>C). This heated gas is then guided via one or more hot gas outlets 83 from the fuel cell system 2’, via a conduit system 50-55 (triple line arrow), and into a combustor chamber 4’’ enclosed by a combustor container 4’. The combustor container 4’ and the combustor chamber 4’’ form parts of a combustor system 4 further comprising a hot gas inlet 80 for allowing entry of the heated gas of temperature T4 and a fuel inlet 81 for the addition of fuel from the one or more fuel reservoirs 15.

The combination of the fuel from the fuel reservoir(s) 15 and the heated gas from the fuel cell system 2’ causes a combustion to take place within the combustor chamber 4’’. Hence, heat is added to the gas flowing through the core of the engine, thereby increasing the gas temperature and the gas volume further.

The gas is then released through a hot nozzle 5 to generate a jet flow 41 (single line arrows). This will result in a reaction force in the opposite direction which is the desired thrust 100 (filled single line arrow) that propels the jet engine 1.

With particular reference to figs. 2 and 3, the compression of gas within the gas container 70 (which in the configuration shown in fig. 2 corresponds to an outer casing 8) may be powered by electric energy generated within the fuel cell 2 and transmitted via power lines 24,31-33 (stippled single line arrow in fig. 3). In general, such electric energy produced by the fuel cell 2 may be used to drive all electrical driven components of the jet engine 1. Further, an auxiliary power supply 25 may be used in conjunction with the fuel cell 2, for example as a mean to start up the jet engine 1.

The source of the compressed gas/air may be a dedicated cooling gas compressor 45’ as exemplified in figs. 5, 7 and 9 and/or from a bypass flow within a turbofan jet engine 1 exemplified in figs. 2 and 3 (compressor 45).

Still with particular reference to fig. 2, the jet engine 1 comprises an outer casing 8 and a concentrically arranged inner casing 9. The outer walls of the inner casing 9 are attached to the inner walls of the outer casing 8 by an outer coupling structure 9’ such as radial struts allowing throughput of gas. A similar coupling structure (not shown) should be provided to support the electric motor 4 against the walls of the inner casing.

The electric motor 3 is configured to drive the compressor 45 and any fan 7 (see below) to supply compressed air to the combustor system 4 and for the bypass flow.

The jet engine 1 also comprises a rotational device such as a fan 7 arranged at or near one end of the outer casing 8 relative to the direction of the thrust 100. The fan 7 may also be driven by the electric motor 3, for example via a gear box (not shown).

The volume enclosed between inter alia the outer casing 8 and the fan 7, hereinafter called the downstream chamber 13 is configured to receive an inlet gas/air 12 (single line arrow) passing through the fan 7 via an upstream chamber 14 (within the outer casing 8 and upstream the fan 7). This inlet gas 12 having entered into the downstream chamber 13 is further split into an outer chamber 13’ located between the outer and inner casings 8,9, downstream the fan 7 and an inner chamber 13’ located between the inner casing 9 and the core arrangement comprising the electric motor 3 and possibly also a dedicated compressor / gas compression device 45, for example upstream the electric motor 3.

The inlet gas 12 passing through the inner chamber 13’ is guided into the combustor chamber 4’’ enclosed by the combustor container 4’ and further out of the hot nozzle 5 located downstream the combustor container 4’. The inlet gas 12 may also be guided into a bypass conduit 23 via a cold gas outlet 84 having a pressure P70 and a temperature T70.

The inlet gas 12 entering the outer chamber 13’ is released from a cold nozzle / bypass nozzle 6 located downstream the end of the outer casing 8 distal from the end with the fan 7. Alternatively, or in addition, the gas 12 may enter the bypass conduit 23.

The bypass conduit 23 is in fluid communication with the fuel cell system 2’, thereby allowing gas / air compressed by the fan 7, and/or a dedicated compressor 45, for example downstream the fan 7, to flow from the downstream chamber 13 (preferably from the inner chamber 13’’) and into the fuel cell 2. As described in connection with fig. 1, the compressed gas of pressure and temperature P70 and T70 is heated to a pressure and temperature P4 and T4, where T4 is significantly higher than T70, due to the fuel driven chemical reactions within the fuel cell 2.

As an alternative exemplary configuration of this first embodiment, the compressed gas from the downstream chamber 13 may be led to a boost compressor prior to entering the fuel cell 2 to further increase the pressure. A boost compressor may also be added after the compressed gas leaves the fuel cell system 2’. The latter solution will however have lower efficiency due to the high temperature of the gases.

Now with particular reference to Fig. 3, the heated gas from the fuel cell 2 is fed into the combustor system 4 (e.g. an afterburner), together with effluent gases (typically unused hydrogen fuel and reaction air), via a fluid conduit system 50.

The fluid conduit system 50 comprises a hot gas conduit 51 (double line arrow) for guiding heated compressed gas, a hot effluent fuel conduit 52 (single line arrow) for guiding effluent fuel such as hydrogen, a hot reaction gas conduit 53 (single line arrow) for guiding effluent reaction gas such as oxygen, a gas mixer 34 for mixing the gases from the three conduits 51-53, a dehumidifier / flow regulator 35 for dehumidifying and/or flow-regulating the mixed gas from the mixer 23, a mixed gas conduit 54 (double line arrow) for guiding gas from the mixer 23 into the dehumidifier / flow regulator 35 and a dehumidifier conduit 55 (double line arrow) for guiding gas from the dehumidifier / flow regulator 35 into the combustor chamber 4’’ of the combustor system 4 via a hot gas combustor inlet 80.

In order to initiate and maintain the chemical reaction within the fuel cell 2, the fuel cell system 2’ is fed with reaction gas such as oxygen and/or air from a reaction gas reservoir 42 and/or surrounding ambient 90. (Note that the term ‘reaction gas reservoir’ does also include ambient air.) Prior to entering the fuel cell system 2’, the reaction gas is fed into a reaction gas compressor 26 via a reservoir reaction gas conduit 22a. After compression, the compressed gas is fed into the fuel cell system 2’ via a compressor reaction gas conduit 22b.

Further, the fuel cell system 2’ is fed with fuel such as hydrogen from a fuel reservoir 15. As for the reaction gas, prior to entering the fuel cell system 2’, the fuel is fed into a fuel compressor 28 via a reservoir fuel conduit 21a. After compression, the compressed fuel is fed into a fuel regulator 17 via a compressor fuel conduit 21b. The fuel is further guided into the fuel cell system 2’ via a regulator fuel conduit 21c as well as into the combustor chamber 4’’’ of the combustor system 4 via a combustor conduit 19. The latter exemplary configuration of the first embodiment allows additional fuel to be added to the combustor system 4 to e.g. increase engine power at take-off and landing.

The jet engine 1 may also comprise a fuel conditioning system (not shown) including a fuel conditioning unit where fuel temperature, pressure and humidity of the gas are conditioned prior to entering the fuel cell. Further, these gases can be preheated using heat from the conduit 54 (between the gas mixer 34 and the dehumidifier 35). The extracted gas may further be heated by going through a heat exchanger (forming part of the fuel conditioning system) and/or using electricity from the fuel cell. In addition, the fuel conditioning system may include a humidifier, for example using humidity extracted by the dehumidifier, in order to provide desired humidity during conditioning.

Electric power to different electric power demanding components of the jet engine such as the electric motor 3 and the compressors 26,28,45’ outside the outer casing 8 may be provided by the fuel cell 2’ via power lines 24,30-33 (stippled single lines).

For the specific example shown in fig. 3, a fuel cell power line 32 extends from the fuel cell system 2’ to a main power line 24, a fuel compressor power line 30 extends from the main line 24 to the fuel compressor 28, a reaction gas compressor power line 31 extends from the main line 24 to the reaction gas compressor 26 and an electric motor power line 33 extends from the main line 24 to the electric motor 3 arranged within the inner casing 9. In this configuration, the dedicated cooling gas compressor 45’ is driven by the electric motor 3. As also depicted in fig. 3, electric power may (in addition or alternatively) be supplied from an auxiliary electric power source 25 via auxiliary power lines 27,29 (line-dot arrows) to the different electric power demanding components 3,26,28. Specifically, an auxiliary reaction gas compressor power line 27 extends from the auxiliary electric power source 25 to the reaction gas compressor 26 and an auxiliary fuel compressor power line 29 extends from the auxiliary electric power source 25 to the fuel compressor 28. A similar auxiliary electric motor power line (not shown) may be envisaged. The auxiliary electric power source 25 may be a set of batteries, a supercapacitor or a motor-generator set that produces electricity from a generator powered by a petro l engine.

Note that at least some of the power lines 24,27,29,30-33 may comprise positive and negative lines from a DC output of the fuel cell system 2’ and/or the auxiliary electric power source 25. This power may need conditioning to match the requirements of the various components on the aircraft, conditioning means changing electric voltage, current and frequency.

The presence of a fan 7 in this first embodiment of the invention gives several advantages: It increases thrust of the jet engine 1 due to the inlet gas 12 flowing into the upstream chamber 14 and further into the downstream chamber 13. It reduces noise of the jet engine 1 since the hot jet flow flowing through the inner chamber 13’’ is enveloped in a low speed cold flow flowing into and through the outer chamber 13’. The latter effect is important for civil aviation as noise pollution may be significant. Finally, it may act as a gas compression device inside the outer casing 8.

Fig. 4 shows another exemplary configuration of the first embodiment. The configuration of the jet engine 1 is identical to the configuration depicted in fig. 3 with the exception that the fluid conduit system 50 further comprises a second stage compressor 37 arranged in fluid communication between the dehumidifier / flow regulator 35 and the combustor chamber 4’’ via the dehumidifier conduit 55 and a second stage compressor conduit 56 (double line arrow). The purpose of the second stage compressor 37 is to further increase the pressure P4 of the hot gases fed into the combustor system 4. Such additional pressure increase will compensate for pressure losses from the first stage compression taking place before entering into the fuel cell 2 and will therefore increase the general performance of the jet engine 1. In fig. 4, the necessary electric power is supplied to the second stage compressor 37 from the fuel cell 2’ via the fuel cell power line 32, the main power line 24 and a second stage compressor power line 38.

A second embodiment of the inventive jet engine 1 is depicted in fig. 5. In clear contrast to the first embodiment the compressed gas of pressure P70 and T70, which is guided into the fuel cell system 2’, is taken from a cooling gas reservoir 10, preferably the ambient air, instead of the downstream chamber 13. The gas from the cooling gas reservoir / ambient air 10 is led into an external cooling compressor 45’. If a dedicated cooling gas reservoir 10 is used, the jet engine 1 may comprise a cooling gas source conduit 22d extending between the reservoir 10 and the cooling compressor 45’. After compression to pressure P70 and temperature T70, the compressed gas is led further into the fuel cell 2 via a cooling compressor conduit 22e and a cold gas inlet 82’.

The necessary electric power to the external cooling compressor 45’ is supplied from the fuel cell 2 via the fuel cell power line 32, the main power line 24 and a cooling compressor power line 46.

The configuration of the second embodiment is for the rest identical to, or near identical to, the first embodiment.

This cooling gas system 10,45’,22d,22e,82’ may either replace the compressed gas system 7,23,45,82 between the downstream chamber 13 and the fuel cell system 2’ or operate in addition to this compressed gas system 7,23,45,82,83.

Another exemplary configuration of the second embodiment is shown in fig. 6. This configuration of the jet engine 1 differs from the configuration of fig. 5 in that the reaction gas compressor 26 and the external cooling gas compressor 45’ has been merged into one common compressor 26,45’. The common compressor 26,45’ is fed with gas from a reaction gas reservoir 42 (for example ambient air) via gas conduits 22a,22d (triple line arrow). Further, the compressed gas/air is guided via a common compressor conduit 22c (triple line arrow) to an inlet gas splitter 60. The inlet gas splitter 60 splits the gas into reaction gas led into the fuel cell system 2’ via a reaction gas conduit 22f (single line arrow) and cooling gas led into the fuel cell system 2 via a cooling gas conduit 22g (triple line arrow). This particular configuration of the second embodiment reduces the number of components and further improves the efficiency.

As shown in fig. 6, the necessary electric power may be provided by the fuel cell 2 and/or the auxiliary electric power source 25.

Note that this configuration, i.e. using a common compressor 26,45’, can be applied to all other configurations using two gas compressors 26,45’ for reaction gas and cooling gas.

For all the above embodiments and exemplary configurations (figs. 2-6), a turbofan jet engine 1 is depicted.

Fig. 7 shows a third embodiment of the invention, where the jet engine 1 is depicted without the above described outer and inner casings 8,9, the downstream chamber 13 and the electric motor 3.

This third embodiment hence further reduces the number of components, resulting in a less complex and lighter jet engine.

Except for the absence of the above-mentioned components, the third embodiment depicted in fig. 7 is identical, or near identical, to the second embodiment depicted in fig. 5.

Another exemplary configuration of the third embodiment is shown in fig. 8. The configuration is similar to the configuration in fig. 7 except that a common compressor 26,45’ and an inlet gas splitter 60 is used as described in connection with fig. 6.

Finally, fig. 9 shows a fourth embodiment of the invention, where a second nozzlecombustor system 11b as described for figs. 7-8 is added to the jet engine 1, thereby providing two jet flows 41 and consequently two thrusts 100a,b. For this embodiment the fuel regulator 17 comprises three outlet conduits 19,a,19b,21c, the regulator fuel conduit 21c, the combustor conduit 19a to feed fuel into one 11a of the two nozzle-combustor systems 11a,b and a second combustor conduit 19b to feed fuel into the second 11b of the two nozzle-combustor systems 11a,b. Moreover, the dehumidifier / flow regulator 35 comprises, in addition to the dehumidifier conduit 55a described above feeding hot gas to the combustor system 4 of the first nozzle-combustor system 11a, a second dehumidifier conduit 55b configured to feed hot gas to the combustor system 4 of the second nozzle-combustor system 11b.

The configuration depicted in fig. 9 is scalable meaning that it may be easily reconfigured to contain any number of nozzle-combustor systems by simply adding the number of conduits from the fuel regulator and the dehumidifier / flow regulator 35.

This fourth embodiment makes the inventive system more flexible in the design of for example an aircraft as a number of smaller size nozzles 5,6 can be used to generate the same amount of thrust, but makes it easier to embed those nozzles 5,6 within the aircraft’s fuselage. This will also reduce drag and increase the overall efficiency of the propulsion system. Hot gases are transferred from the fuel cell 2 to the combustor system / after burner 4 through piping and tubing.

Another advantage of this fourth embodiment is that multiple nozzles can (in addition to providing thrust) be used to control the direction and maneuvers of the aircraft by controlling the amount of thrust from each nozzle. This configuration bears some similarities with the workings of a drone, though in the horizontal direction.

In the preceding description, various aspects of the jet engine have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the engine and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the engine, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention.

Reference numerals:

Claims

1. A jet-engine (1) comprising

- an outer casing (8) having an opening end for allowing inlet gas (12) to enter therein,

- a combustor system (4) comprising

o a combustor container (4’) enclosing a combustor chamber (4’’), wherein a first end of the combustor container (4’) is arranged in fluid communication with an end of the outer casing (8) opposite the opening end,

o a hot gas combustor inlet (80) for allowing gas to enter within the combustor chamber (4’’) and

o a fuel combustor inlet (81) for allowing fuel to enter within the combustor chamber (4’’),

- a fuel source (15,17) in fluid communication with the fuel combustor inlet (81),

- a nozzle (5) configured to exhaust jet flow gas (41) out of the jet-engine (1) at one side and arranged in fluid communication with the combustion chamber (4’’) at a second, opposite end and

- a cold gas outlet (84) for allowing gas to exhaust from the outer casing (8),

characterized in that the jet engine (1) further comprises

- a fuel cell system (2’) comprising

o a fuel cell (2),

o a fuel and reaction gas inlet (85) for allowing fuel and reaction gas to enter into the fuel cell (2),

o a cold gas inlet (82,82’) for allowing gas to enter into the fuel cell (2) and

o a hot gas outlet (83) for allowing gas to exhaust out of the fuel cell (2),

- a cold gas conduit (22,23) in fluid communication between the cold gas outlet (84,84’) and the cold gas inlet (82,82’) and

- a hot gas conduit system (34,35,50-55) in fluid communication between the hot gas outlet (83) and the hot gas combustor inlet (80).

2. The jet engine (1) in accordance with claim 1, wherein the jet engine (1) further comprises

- gas compressor means (13’’,26,45,50) comprising

o a gas container (9,70) and

o a gas compression device (7,45) configured to compress a gas within the gas container (9,70) to an elevated pressure (P70) wherein the cold gas outlet (84) is in fluid communication with the gas container (9,70).

3. The jet engine (1) in accordance with claim 1 or 2, wherein the jet engine (1) further comprises

a fuel regulator (17) in fluid communication with a fuel reservoir (15),

a combustor conduit (19) in fluid communication between the fuel regulator (17) and the combustor chamber (4’’) and

a regulator fuel conduit (21c) in fluid communication between the fuel regulator (17) and the fuel and reaction gas inlet (85,85’) of the fuel cell system (2’).

4. The jet engine (1) in accordance with any one of the preceding claims, wherein the fuel cell system (2’) comprises

a fuel inlet (85’) for allowing fuel to enter into the fuel cell (2’) from a fuel reservoir (15) and

a reaction gas inlet (85’’) for allowing reaction gas to enter into the fuel cell (2) from a reaction gas reservoir (42).

5. The jet engine (1) in accordance with claim 4, wherein the jet engine (1) further comprises

a reaction gas reservoir (42) comprising a reaction gas outlet (42’) and

a reaction gas conduit (22) in fluid communication between the reaction gas outlet (42’) and the reaction gas inlet (85’’) of the fuel cell system (2’).

6. The jet engine (1) in accordance with any one of the preceding claims, wherein the jet engine (1) further comprises

a fuel reservoir (15) comprising a fuel outlet (15’) and

a fuel conduit (21a,b) in fluid communication between the fuel outlet (15’) and fuel inlet (85’) of the fuel cell system (2’).

7. The jet engine (1) in accordance with any one of the preceding claims, wherein the hot gas conduit system (34,35,50-55) comprises

a dehumidifier (35) for dehumidification of the gas exhausted from the hot gas outlet (83) of the fuel cell system (2’).

8. The jet engine (1) in accordance with any one of the preceding claims, wherein the hot gas conduit system (34,35,55-55) comprises

a gas mixer (34) for mixing of gases exhausted from the hot gas outlet (83) of the fuel cell system (2’).

9. The jet engine (1) in accordance with any one of the preceding claims, wherein the hot gas conduit system (34,35,50-55) comprises

a dehumidifier (35) for dehumidification of the gas exhausted from the hot gas outlet (83) of the fuel cell system (2’) and

a gas mixer (34) for mixing of gases exhausted from the hot gas outlet (83) of the fuel cell system (2’),

wherein the gas mixer (34) is arranged upstream the dehumidifier (35).

10. The jet engine (1) in accordance with any one of the preceding claims, wherein the jet engine (1) further comprises

the gas compressor means (13’’,26,45,50) comprising the gas container (9,70) and the gas compression device (7,45) configured to compress a gas within the gas container (9,70) to an elevated pressure (P70), wherein the cold gas outlet (84) is in fluid communication with the gas container (9,70),

wherein the fuel cell (2) is configured to generate chemical energy from a chemical reaction between the fuel and the reaction gas when entering into the fuel cell (2) and to produce electric power from the generated chemical energy and

wherein the jet engine (1) further comprises a fuel cell power line (32,33) extending between the fuel cell (2) and the gas compression device (7,45) for providing the gas compression device (7,45) with electric power.

11. The jet engine (1) in accordance with any one of the preceding claims, wherein the fuel cell system (2’) further comprises

a second hot gas outlet for allowing effluent reaction gas to exhaust out of the fuel cell (2), the second hot gas outlet (83) being in fluid communication with the hot gas combustor inlet (80).

12. The jet engine (1) in accordance with any one of the preceding claims, wherein the jet engine (1) further comprises

a fan (7) arranged within the outer casing (8) such that the outer casing (8) is separated into an upstream chamber (14) configured to allow the inlet gas (12) to enter therein and a downstream chamber (13) and

an electric motor (3) rotationally coupled to the fan (7), the electric motor (3) being powered by electric power from the fuel cell system (2’)

13. The jet engine (1) in accordance with claim 12, wherein the jet engine (1) further comprises

an inner casing (9) separating the downstream chamber (13) into an outer chamber (13’) and an inner chamber (13’’) arranged coaxially within the outer chamber (13’),

wherein the inner chamber (13’) is in fluid communication with the first end of the combustor container (4’).

14. The jet engine (1) in accordance with any one of the preceding claims, wherein the jet engine (1) further comprises

a cooling gas source (10),

a cooling gas compressor (45’),

a cooling gas source conduit (22d) in fluid communication between the cooling gas source (10) and the cooling gas compressor (45’) and a cooling gas compressor conduit (22e) in fluid communication between the cooling gas compressor (45’) and the cold gas inlet (82’) of the fuel cell system (2’).

15. The jet engine (1) in accordance with claim 14, wherein the jet engine (1) further comprises

the gas compressor means (13’’,26,45,50) comprising the gas container (9,70) and the gas compression device (7,45) configured to compress a gas within the gas container (9,70) to an elevated pressure (P70), wherein the cold gas outlet (84) is in fluid communication with the gas container (9,70) and

a cooling gas compressor power line (46) extending between the fuel cell (2) and the cooling gas compressor (45’) for providing the cooling gas compressor (45’) with electric power.