Patent Description:
A conventional fuel cell system comprises a hydrogen distribution, such as one or more pipes conducting hydrogen. Since hydrogen may leak or permeate from the hydrogen distribution, venting of the hydrogen distribution is required. Some systems provide a shrouded pipe, in order to collect any leaked or permeated hydrogen.

The documents <CIT>, <CIT>, <CIT> and <CIT> disclose fuel cell systems comprising a hydrogen disribution.

However, a sensor system in the shrouded pipe is required, in order to detect a hydrogen level in the shroud. Otherwise, accumulation of hydrogen may increase the risk of an explosive mixture and/or an uncontrolled burning of the hydrogen.

It is therefore an object of the present disclosure to provide an improved fuel cell system, particularly a more secure fuel cell system.

This object is solved by the present invention as defined in the independent claims.

According to a first aspect to better understand the present disclosure, a fuel cell system comprises a fuel cell, a fuel tank, a fuel distribution pipe fluidly connecting the fuel tank with a fuel inlet of the fuel cell, and a shroud surrounding at least a portion of the fuel distribution pipe. Thus, the shroud encases the fuel distribution pipe (i.e., forms a shrouded pipe for fuel distribution) and allows catching or collecting hydrogen leaking or permeating from the fuel distribution pipe.

It is to be understood that the fuel cell system may comprise more than one fuel tank and/or more than one fuel cell, so that more than one fuel distribution pipe is present in the system, together forming a fuel distribution. Any portion of the fuel distribution or the entire fuel distribution (all fuel distribution pipes) can be equipped with such shroud.

Furthermore, the fuel cell system comprises an inerting system configured to generate nitrogen enriched air (NEA) and oxygen enriched air (OEA). Such inerting system can be any system receiving an air stream and splitting the air stream into a first portion containing more nitrogen than the received air stream, and a second portion containing more oxygen than the received air stream.

The fuel cell system also comprises an NEA pipe conducting the nitrogen enriched air into the shroud. Thus, the fuel distribution pipe is surrounded by nitrogen enriched air. In other words, a shrouded pipe for fuel distribution is formed that surrounds the actual fuel pipe with a gas containing less or no oxygen. Any fuel, such as hydrogen, methane or other fuel for a fuel cell, leaking or permeating from the fuel distribution pipe will not come into contact with oxygen. Therefore, the risk of having a critical mixture of fuel and oxygen (eventually leading to burning of the fuel or an explosion) is significantly reduced.

Furthermore, since the inerting system can continuously generate nitrogen enriched air, a flow of NEA through the shroud can be achieved. This flow of NEA is venting or transporting any fuel leaking or permeating out of the fuel distribution pipe outboard of the fuel distribution by the NEA flow. Thus, there is no need for a fuel detection system inside the shroud.

In an implementation variant, the fuel cell system can further comprise an OEA pipe conducting the oxygen enriched air (from the inerting system) to an oxidiser inlet of the fuel cell. Thus, oxygen enriched air allows a performance increase of the fuel cell compared to providing normal air to the oxidiser inlet of the fuel cell. The fuel cell system, hence, can be operated more efficiently and more secure. At the same time, the overall weight of the fuel cell system may only slightly increase. That is, the inerting system may increase the overall weight, while the fuel cell itself may be designed smaller and, hence, lighter due to the higher efficiency.

In another implementation variant, the fuel cell system can comprise a pressure sensor in the fuel distribution pipe. If the pressure sensor indicates a pressure drop, a leakage of fuel from the fuel distribution pipe can be detected. Such pressure sensor may already be included in a conventional fuel cell system, for example, for sensing a fuel pressure at a fuel inlet of the fuel cell.

In a further implementation variant, the inerting system can be supplied with pressurised air. This allows operating the inerting system with higher efficiency and larger output flows of NEA and OEA.

In yet a further implementation variant, the fuel tank can store hydrogen. Hydrogen is a very volatility gas and can leak or permeate more easily from a fuel distribution pipe compared to other gases. Thus, the disclosed fuel cell system is particularly secure for hydrogen operated fuel cells.

According to a second aspect to better understand the present disclosure, an aircraft comprises at least one fuel cell system according to the first aspect or one of its variants. As a mere example, the aircraft may employ the fuel cell to generate electricity for operating certain control components of the aircraft.

In an implementation variant, the aircraft can further comprise an engine supplied with energy generated by the fuel cell. For example, the fuel cell can generate electricity, which is used to drive an electric motor propelling the aircraft.

In another implementation variant, the aircraft can further comprise a liquid fuel tank, and an engine supplied with liquid fuel from the liquid fuel tank. The liquid fuel in the liquid fuel tank can be kerosene, gasoline, diesel or the like. Thus, the engine of the aircraft can be a conventional motor and/or jet engine of an aircraft. As a mere example, the liquid fuel tank can be arranged in the wings of the aircraft.

Furthermore, the fuel cell system can further comprise a further NEA pipe conducting nitrogen enriched air from the inerting system into the liquid fuel tank. Thus, the further NEA pipe is different from the NEA pipe conducting the nitrogen enriched air into the shroud.

In any case, the inerting system can be a conventional inerting system in the aircraft, that is installed to fill the liquid fuel tank with NEA. Thus, the inerting system can be additionally used for the fuel cell system, so that an efficient operation of the aircraft is possible. Likewise, the OEA from the inerting system can be employed to operate the fuel cell in a more efficient manner due to the higher level of oxygen.

The present disclosure is not restricted to the aspects and variants in the described form and order. Specifically, the description of aspects and variants is not to be understood as a specific limiting grouping of features. It is to be understood that the present disclosure also covers combinations of the aspects and variants. Thus, each variant or optional feature can be combined with any other aspect, variant, optional feature or even combinations thereof.

In the following, the present disclosure will further be described with reference to exemplary implementations illustrated in the figures, in which:.

It will be apparent to one skilled in the art that the present disclosure may be practiced in other implementations that depart from these specific details.

<FIG> schematically illustrates a fuel cell system <NUM> comprising a fuel cell <NUM>. The fuel cell <NUM> is configured to perform an electrochemical reaction, where fuel and an oxidiser react, such as hydrogen and oxygen, or methane, propane or other liquid or gaseous fuel reacting with oxygen from the oxidiser, and electric energy is generated and supplied by the fuel cell <NUM>. For instance, the fuel cell <NUM> has an oxidiser inlet <NUM> and a fuel inlet <NUM>. Furthermore, the fuel cell <NUM> has an energy terminal <NUM> and/or water outlet <NUM> (illustrated as one outlet for increased gravity).

Furthermore, the fuel cell system <NUM> comprises a fuel tank <NUM>, such as the illustrated hydrogen tank <NUM>. The fuel tank <NUM> is fluidly connected to the fuel cell <NUM>, particularly the fuel inlet <NUM>, via a fuel distribution pipe <NUM>. It is to be noted, that the fuel distribution pipe <NUM> can extend from the fuel tank <NUM> to the fuel inlet <NUM> of the fuel cell <NUM> irrespective of its illustrated size, which is for explanation purposes only.

The fuel cell system <NUM> comprises a shroud <NUM> surrounding at least a portion of the fuel distribution pipe <NUM>. In other words, the fuel from the fuel tank <NUM> is flowing through a shrouded pipe <NUM>/<NUM> to the fuel inlet <NUM> of the fuel cell <NUM>. The shroud <NUM> forms an interior space between the fuel distribution pipe <NUM> and the shroud <NUM>, wherein any fuel leaking or permeating through the fuel distribution pipe <NUM> can be collected and accumulated.

In addition, the fuel cell system <NUM> comprises an inerting system <NUM> configured to generate nitrogen enriched air (NEA) and oxygen enriched air (OEA). Such inerting system <NUM> can be any conventional inerting system <NUM>. As a mere example, at an inlet <NUM> the inerting system <NUM> is provided with air, for example pressurised air. The inerting system <NUM> comprises respective outlets for NEA and OEA.

The fuel cell system <NUM> comprises an OEA pipe <NUM> and an NEA pipe <NUM> respectively conducting the oxygen enriched air and the nitrogen enriched air generated by the inerting system <NUM>. For instance, the NEA pipe <NUM> conducts the nitrogen enriched air (NEA) into the shroud <NUM>. This allows surrounding the fuel distribution pipe <NUM> with nitrogen enriched air, i.e., oxygen reduced air, which significantly reduces the risk of an explosive mixture of fuel and oxygen, if fuel leaks or permeates through the fuel distribution pipe <NUM>.

In order to detect a leakage or fuel permeating from the fuel distribution pipe <NUM>, a pressure sensor (not explicitly illustrated) can be provided, for example, at the fuel inlet <NUM> of the fuel cell <NUM>. Such pressure sensor may be required anyway for the normal operation of the fuel cell <NUM>, in order to provide a sufficient amount of fuel depending on the operating state of the fuel cell <NUM>.

In addition, the fuel cell system <NUM> can include an NEA exhaust pipe <NUM> conducting NEA from the shroud <NUM> into the ambient environment or another component capable of dealing with NEA that may include (small) portions of fuel leaked or permeated from the fuel distribution pipe <NUM>. Since the inerting system <NUM> can continuously generate NEA that is guided through the shroud <NUM> and through the NEA exhaust pipe <NUM>, a continuous flow of NEA conveying any leaked or permeated fuel away from the fuel distribution pipe <NUM> can be achieved. This further increases security of the fuel cell system <NUM>.

<FIG> schematically illustrates an aircraft <NUM> comprising such fuel cell system <NUM>. The aircraft <NUM> can comprise an engine <NUM> that is applied with energy generated by the fuel cell <NUM>. <FIG> illustrates a connection between the engine <NUM> and the fuel cell system <NUM> with a single line, which can represent an electric connection between the fuel cell terminal <NUM> and the engine <NUM>.

Alternatively or additionally, the aircraft <NUM> can comprise an engine <NUM> and a liquid fuel tank <NUM>, wherein the engine <NUM> is supplied with liquid fuel from the liquid fuel tank <NUM> (such liquid fuel pipe is not illustrated in <FIG> for brevity reasons). It is to be understood that more than one liquid fuel tank <NUM> can be provided. <FIG> illustrates only one liquid fuel tank <NUM> for brevity reasons. Thus, a conventional propeller and/or jet engine <NUM> can be employed in the aircraft <NUM>. The inerting system <NUM> of the fuel cell system <NUM> can be used to generate NEA that is conducted into the liquid fuel tank <NUM>. Such inerting system <NUM> is common in a majority of aircrafts <NUM> having a liquid fuel tank <NUM>.

Furthermore, the inerting system <NUM> can be provided with pressurised air from the engine <NUM>, such as bleed air from jet engine <NUM>. Such pressurised air is separated by the inerting system <NUM> into NEA and OEA.

The NEA conducted into the liquid fuel tank <NUM> may be provided separately from the shroud <NUM>, for example, directly from the NEA outlet <NUM> of the inerting system <NUM> via further NEA pipe <NUM> (<FIG>). <FIG> illustrates only one pipe between the liquid fuel tank <NUM> and the fuel cell system <NUM> for brevity reasons, although more pipes and lines may be provided.

Thus, weight, energy and resource synergies can be leveraged in the aircraft <NUM>. For instance, no additional inerting system <NUM> is required for the fuel cell system <NUM>, in case of a liquid fuel propelled aircraft <NUM>. Moreover, electric energy can be generated by the fuel cell <NUM> in the aircraft <NUM> in a more secure manner.

Claim 1:
A fuel cell system (<NUM>), comprising:
a fuel cell (<NUM>);
a fuel tank (<NUM>);
a fuel distribution pipe (<NUM>) fluidly connecting the fuel tank (<NUM>) with a fuel inlet (<NUM>) of the fuel cell (<NUM>);
a shroud (<NUM>) surrounding at least a portion of the fuel distribution pipe (<NUM>);
an inerting system (<NUM>) configured to generate nitrogen enriched air, NEA, and oxygen enriched air, OEA; and
an NEA pipe (<NUM>) conducting the nitrogen enriched air into the shroud (<NUM>).