Patent Description:
Fuel efficiency of engines can be an important consideration in the selection and operation of the engines. For example, fuel efficiency of gas turbine engines in aircraft can be an important (and a limiting) factor on how far the aircraft can travel. Some aircraft propulsion systems can include fuel cells in addition to the gas turbine engines. These fuel cells can be located upstream of or surrounding combustors and downstream from compressors of the gas turbine engines. Compressed air that is output by the compressors flows along the length of the engine and into the fuel cells. Part of this air is consumed by the fuel cells in generating electrical energy. The rest of the air can flow through or around the fuel cells and into a combustor. This air is then mixed with fuel and combusted in a combustor of the engine.

One problem with known fuel cell-combustor combinations is the requirement of conduits to direct the flow of air into the fuel cells and out of the fuel cells into the combustor. These conduits can increase the size of the fuel cell and engine combination. In addition, the air coming from the compressor must generally be heated to ensure that the air is sufficiently hot for consumption within the fuel cells. This heating of the air coming from the compressor can require the inclusion of heating elements, such as heat exchangers, which further increases the weight and volume of the system. <CIT> discloses a pressurized fuel cell system operating within a common pressure vessel, where the system contains fuel cells, a turbine and a generator. <CIT> discloses a fuel cell and gas turbine combined cycle system which includes dual fuel cell cycles combined with a gas turbine cycle.

The invention as defined by independent claim <NUM> is an engine assembly comprising: (a) a combustor; (b) a fuel cell stack integrated with the combustor, the fuel cell stack configured to direct fuel and air exhaust from the fuel cell stack into the combustor; and (c) a pre-burner system fluidly connected to the fuel cell stack, the pre-burner system being configured to control a temperature of an air flow directed into the fuel cell stack, wherein the combustor is configured to combust the fuel and air exhaust from the fuel cell stack into one or more gaseous combustion products that drive a downstream turbine. The engine assembly further comprises a catalytic partial oxidation convertor that is fluidly connected to the fuel cell stack, wherein the catalytic partial oxidation convertor is configured to develop a hydrogen rich fuel stream to be directed into the fuel cell stack. The engine assembly further comprises a fuel source that provides fuel and is fluidly connected to the pre-burner system and the catalytic partial oxidation convertor, wherein (i) a first portion of the fuel is directed from the fuel source to the pre-burner system to raise a temperature of a portion of air directed into the pre-burner system from a compressor, and (ii) a second portion of the fuel is directed from the fuel source to the catalytic partial oxidation convertor for developing the hydrogen rich fuel stream.

Additional features, advantages, and embodiments of the present disclosure are set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the disclosure as claimed.

The foregoing and other features and advantages will be apparent from the following, more particular, description of various exemplary embodiments, as illustrated in the accompanying drawings, wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

Various embodiments are discussed in detail below. While specific embodiments are discussed, this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without departing from the scope of the appended claims.

The present disclosure relates to a combination of a combustion system with an integrated fuel cell for a gas turbine engine. The present disclosure further relates to the inclusion of (i) a pre-burner system for controlling the air temperature of the fuel cell that is integrated within the combustor of the gas turbine engine, and/or (ii) a catalytic partial oxidation convertor for developing a hydrogen rich fuel stream. For example, gas turbine engines, such as those used with airplanes, function with variable altitude and operating conditions, which results in air being discharged from the compressor having a variable temperature that can range from <NUM> to <NUM>. However, fuel cell technology, such as solid oxide fuel cells (SOFCs), usually requires the cell to operate at, for example, <NUM> to <NUM> to be efficient, and with a fuel stream rich in hydrogen and carbon monoxide. Thus, according to embodiments of this disclosure, a pre-burner system can be included to control the air temperature leaving the pre-burner system toy, for example, an operating point of the fuel cell (e.g., SOFC), including, e.g., <NUM> to <NUM>, at all operating conditions.

In general, a solid oxide fuel cell consumes between <NUM>% and <NUM>% of the fuel energy in generating electricity. Traditional fuel cells keep the air and fuel sides of the fuel cell separate and recycle the fuel to maximize conversion of fuel in the fuel cycle. This requires a substantial balance of heat exchangers, pumps, and plumbing, all of which can be eliminated by the integrated combustor and fuel cell of the present disclosure. For example, according to embodiments of this disclosure, unburned fuel and air from the solid oxide fuel cell are dumped directly into the gas turbine combustor and consumed.

According to one embodiment of the present disclosure, a combination of a combustion system with an integrated fuel cell for a gas turbine engine is combined with (i) a catalytic partial oxidation (C-POX) convertor for developing a hydrogen rich fuel stream and (ii) a pre-burner system for raising the air temperature to, for example, an operating point (e.g., <NUM> to <NUM>) for a solid oxide fuel cell that is designed into the outer and/or inner liners of the gas turbine combustor and/or up to <NUM> less than and/or up to <NUM> more than the operating point of the fuel cell. In operation, a pilot/main burner, typically present in conventional gas turbine combustors, is used to start the gas turbine engine and to increase the operating temperature, pressure, and mass flow of air. Once the temperature, pressure, and mass air flow are sufficiently high, a portion of fuel is diverted to (i) the catalytic partial oxidation (C-POX) convertor and (ii) the pre-burner system to increase the temperature of a portion of air coming from the compressor to facilitate the functioning of the solid oxide fuel cell located within the combustor liner region. A hydrogen and carbon monoxide stream, which is developed in the catalytic partial oxidation convertor, is utilized along with the air heated by the pre-burner system in the solid oxide fuel cell to generate electrical power. Unburned fuel and air from the solid oxide fuel cell is channeled into the combustor where a pilot/main flame is present and provides ignition to consume any unburned hydrogen and carbon monoxide effluents from the solid oxide fuel cell. The heated air is then channeled into the gas turbine nozzle for work extraction by the turbine.

According to one embodiment, hydrogen (H<NUM>) fuel can be used as one of the fuel sources with the combustion system having the integrated fuel cell, as opposed to (or in addition to) a hydrocarbon fuel source. According to this embodiment, a catalytic partial oxidation (C-POX) convertor may not be necessary for this hydrogen (H<NUM>) fuel source, and thus, the hydrogen (H<NUM>) fuel stream can be directed into the fuel cell (e.g., SOFC) that is designed into the outer and/or inner liners of the gas turbine combustor. According to one embodiment, when hydrogen (H<NUM>) fuel is the fuel source, a heat-exchanger, a pre-burner system, and/or a catalytic partial oxidation (C-POX) convertor can be included to control the temperature of the hydrogen (H<NUM>) fuel to at least one of (i) an operating point of the fuel cell (e.g., SOFC), (ii) up to <NUM> less than the operating point of the fuel cell (e.g., SOFC), and (iii) up to <NUM> more than the operating point of the fuel cell (e.g., SOFC).

According to another embodiment, the pre-burner system is configured to increase the temperature of a portion of air coming from the compressor to facilitate the functioning of the fuel cell located within the combustor liner region. For example, according to one embodiment, if the operating point of the fuel cell (e.g., SOFC) is <NUM>, the pre-burner system is configured to increase the temperature of a portion of air coming from the compressor to <NUM> to <NUM>. According to another embodiment, if the operating point of the fuel cell (e.g., SOFC) is <NUM>, the pre-burner system is configured to increase the temperature of a portion of air coming from the compressor to <NUM> to <NUM>. According to yet another embodiment, if the operating point of the fuel cell (e.g., SOFC) is <NUM>, the pre-burner system is configured to increase the temperature of a portion of air coming from the compressor to <NUM> to <NUM>.

One or more embodiments described herein provide fuel cell and combustor assemblies for engine systems, such as, e.g., gas turbine engines of aircraft (or other vehicles or stationary power-generating systems). The assemblies (and accompanying methods described herein) integrate fuel cells (e.g., solid oxide fuel cells) and a combustor of an engine to provide electrical power and propulsion power in a thermally efficient manner. A fuel cell stack is arranged around the exterior of a combustor of the engine such that air flows radially inward through the fuel cells in the fuel cell stack, and into the combustor toward a center or annular axis of the combustor. The fuel cell stack can be integrated directly into the outer and/or inner liners of the combustor or combustion chamber such that no additional conduits or ducting is needed to fluidly couple the fuel cell stack with the combustor.

The fuel cell and combustor assemblies described herein can be used to generate electrical power for the creation of thrust in addition to that provided by engine exhaust. For example, the draw of electrical current from the fuel cell stack in a gas turbine engine can be used to power one or more motors that add torque to a fan of the gas turbine engine. This increases overall fuel efficiency of a propulsion system that includes the fuel cells and combustors. For example, there is potential for at least a <NUM>% or more reduction in fuel burn to complete a mission.

<FIG> illustrates one embodiment of a combination of a combustion system with an integrated fuel cell (i.e., a fuel cell and combustor assembly <NUM>) used in a gas turbine engine <NUM>. The gas turbine engine <NUM> includes a shaft <NUM> that mechanically connects at least one compressor <NUM> to a turbine <NUM>. The at least one compressor <NUM> receives inlet air and compresses this air via one or more stages of rotating blades. The compressed air is directed into the fuel cell and combustor assembly <NUM>.

The assembly <NUM> includes an annular combustor <NUM> that is circumferentially surrounded along some or all of the length of the combustor <NUM> by a fuel cell stack <NUM>. The fuel cell stack <NUM> includes multiple fuel cells arranged to convert fuel and compressed air from the compressor <NUM> into electrical energy. The fuel cell stack <NUM> can be integrated into the outer portion of the combustor <NUM> such that the fuel cell stack <NUM> is part of the combustor <NUM> and is located radially outside of the combustor <NUM> (e.g., relative to an annular axis <NUM> of the combustor <NUM>). The engine system <NUM> includes a center axis <NUM> that may be coincident with the annular axis <NUM> or may not be coincident with the annular axis <NUM>.

Some of the compressed air exiting the compressor <NUM> is directed through the fuel cells in the fuel cell stack <NUM> in radially inward directions toward the annular axis <NUM> of the combustor <NUM>. Some or all of the remaining amount of compressed air from the compressor <NUM> is directed into the combustor <NUM> in a direction or directions along or parallel to the annular axis <NUM> of the combustor <NUM>.

The fuel cells in the fuel cell stack <NUM> receive fuel from fuel manifolds and air from the compressor <NUM>, and convert this fuel and air into electrical energy. Partially oxidized fuel and air exhaust from the fuel cells in the fuel cell stack <NUM> flow radially inward into the combustor <NUM> toward the annular axis <NUM>. The partially consumed fuel and air exhaust from the fuel cells, additional air from the compressor <NUM>, and/or additional fuel from one or more fuel injectors for pilot/main burners, typically present in a conventional gas turbine combustor, are combusted within the combustor <NUM>. Exhaust from the combusted fuel and air mixture is then directed into the turbine <NUM>, which converts the exhaust into rotating energy via the shaft <NUM> that can be used to power one or more loads <NUM>, such as a fan used to propel a vehicle (e.g., an aircraft), a generator, or the like. According to one embodiment, the shaft <NUM> is a single shaft that connects the load or fan <NUM> to the compressor <NUM> and the turbine <NUM>. According to another embodiment, the shaft <NUM> comprises (i) an outer shaft that connects the compressor <NUM> to the turbine <NUM>, and (ii) an inner shaft that connects the load or fan <NUM> to the turbine <NUM>.

<FIG> schematically illustrates one embodiment of the combination of a combustion system with an integrated fuel cell (i.e., the fuel cell and combustor assembly <NUM> shown in <FIG>). As described above, the assembly <NUM> includes the fuel cell stack <NUM> located radially outward of the combustor <NUM> relative to the annular axis <NUM> of the combustor <NUM>. The fuel cell stack <NUM> includes several fuel manifolds <NUM> located at different portions along the perimeter of the combustor <NUM>. The number and/or arrangement of the fuel manifolds <NUM> shown in <FIG> is one embodiment and is not limiting on all embodiments of described herein.

The fuel manifolds <NUM> are conduits that receive fuel for the fuel cells in the stack <NUM> and distribute the fuel to the cells. The fuel manifolds <NUM> can be fluidly coupled with a source of the fuel, such as one or more tanks or other containers of the fuel. The fuel manifolds <NUM> can include orifices that deliver the fuel to the fuel cells in locations that deliver fuel into fuel flow passages. In one embodiment, the fuel is not simply injected from the fuel manifolds <NUM> through orifices into the air stream through the combustor <NUM>. Instead, the fuel can be directed into flow passages as described in, for example, <CIT>. As further shown in <FIG>, the fuel manifolds <NUM> can be elongated conduits that are elongated along directions that are parallel to or otherwise along the annular axis <NUM> of the combustor <NUM>. Alternatively, the fuel manifolds <NUM> can have another shape, such as rings that encircle the combustor <NUM>.

In one embodiment, the fuel manifolds <NUM> can be individually controlled. For example, a controller (or control system) (e.g., hardware circuitry that includes and/or is coupled with one or more processors, such as microprocessors) can control valves which, in turn, control the flow of fuel to different ones of the fuel manifolds <NUM>. The amount of current that is drawn from the fuel cell stack <NUM> can be controlled (e.g., by the controller) during operation of an engine that includes the assembly <NUM>. The controller can close or open valves to decrease or to increase (respectively) the amount of fuel flowing into the fuel cell stack <NUM>. The amount of fuel flowing into the fuel cell stack <NUM> can be decreased to decrease the electrical current generated by the fuel cell stack <NUM>, or can be increased to increase the current generated by the fuel cell stack <NUM>. Optionally, no fuel can be delivered to the fuel cell stack <NUM> via the manifolds <NUM> to prevent the fuel cell stack <NUM> from generating any electrical current.

The fuel cell stack <NUM> directly abuts the combustor <NUM> along the length of the combustor <NUM>. The fuel cell stack <NUM> can form the outer surface or boundary of the combustor <NUM>. This can include the fuel cell stack <NUM> being integrally formed with the combustor <NUM>. This arrangement reduces or eliminates the need to include additional ducting to fluidly couple the fuel cell stack <NUM> with the combustor <NUM>. The combustor <NUM> receives unspent fuel and air from the fuel cell stack <NUM> along radially inward directions oriented toward the annular axis <NUM> of the combustor <NUM>. The combustor <NUM> also can receive supplemental fuel and air from the compressor <NUM>. This supplemental fuel and air does not pass or flow through any fuel cells in the fuel cell stack <NUM>, and can flow into the combustor <NUM> in directions along or parallel to the annular axis <NUM>. The combustor <NUM> further includes an interior portion <NUM> that is coupled with the compressor <NUM> and/or the turbine <NUM>, via, e.g., a shaft (see, e.g., shaft <NUM> of <FIG>).

<FIG> illustrates a cross-sectional view of one embodiment of a combination of the combustion system with an integrated fuel cell (i.e., the fuel cell and combustor assembly <NUM> of <FIG>) along line <NUM>-<NUM> shown in <FIG>. As shown, the fuel cell stack <NUM> circumferentially extends around the combustor <NUM> by completely encircling the combustor <NUM> around the annular axis <NUM>. The fuel cell stack <NUM> includes several fuel cells <NUM> that generate electrical current. These fuel cells <NUM> are solid oxide fuel cells in one embodiment. Alternatively, the fuel cells <NUM> can be another type of fuel cell. The fuel cells <NUM> are formed as parts or segments of an annulus that encircles the combustor <NUM>.

The fuel cells <NUM> that are visible in <FIG> may be a single ring or an annulus of fuel cells <NUM> that encircles the combustor <NUM>, with many more fuel cells <NUM> axially stacked together to form the fuel cell stack <NUM>. For example, multiple additional rings of fuel cells <NUM> may be placed on top of each other to form the fuel cell stack <NUM> that is elongated along the annular axis <NUM>. While eight fuel cells <NUM> are shown in the ring in <FIG>, more or fewer fuel cells <NUM> can form the ring that encircles the combustor <NUM>.

The fuel cells <NUM> in the stack <NUM> are positioned to receive discharged air <NUM> from the compressor <NUM> (and/or a pre-burner system as described further below) and fuel <NUM> from the fuel manifolds <NUM> (and/or a catalytic partial oxidation convertor as described further below). The fuel cells <NUM> generate electrical current using this air <NUM> and at least some of this fuel <NUM>, and radially direct partially oxidized fuel <NUM> and unused air <NUM> into the combustor <NUM> toward the annular axis <NUM>. The combustor <NUM> combusts the partially oxidized fuel <NUM> and air <NUM> into one or more gaseous combustion products (e.g., exhaust), that are directed into and drive the downstream turbine <NUM>.

<FIG> illustrates a perspective view of another embodiment of a combination of a combustion system with an integrated fuel cell (i.e., a fuel cell and combustor system <NUM>) that can be used in a gas turbine engine system (e.g., gas turbine engine <NUM> of <FIG>), which is further described in, e.g., <CIT>. The system <NUM> includes a housing <NUM> having a combustion outlet side <NUM> and a side <NUM> that is opposite to the combustion outlet side <NUM>, a fuel and air inlet side <NUM> and a side <NUM> that is opposite to the fuel and air inlet side <NUM>, and sides <NUM>, <NUM>. The sides <NUM> and <NUM> are not visible in the perspective view of <FIG>. The shape of the housing <NUM> may differ from what is shown in <FIG>. For example, the housing <NUM> need not have a rectangular or a cubic shape, in another embodiment.

The outlet side <NUM> includes several combustion outlets <NUM> from which combustion gas(es) <NUM> is directed out of the housing <NUM>. As described herein, the combustion gas <NUM> can be created using fuel and air that is not consumed by fuel cells in a fuel cell stack inside the housing <NUM>. This combustion gas <NUM> can be used to generate propulsion or thrust for a vehicle, such as a manned or an unmanned aircraft.

The air inlet side <NUM> includes one or more fuel inlets <NUM> and one or more air inlets <NUM>. Optionally, one or more of the inlets <NUM>, <NUM> can be on another side of the housing <NUM>. The fuel inlet <NUM> is fluidly coupled with a source of fuel for the fuel cells, such as one or more pressurized containers of a hydrogen-containing gas and/or a catalytic partial oxidation convertor as described further below. Alternatively, another type or source of fuel may be used. The air inlet <NUM> is fluidly coupled with a source of air for the fuel cells, such as air that is discharged from a compressor provided with a gas turbine engine (see, e.g., air <NUM> coming from compressor <NUM> in the gas turbine engine system <NUM> of the embodiment of <FIG>) and/or a pre-burner system as described further below. Alternatively, another source of air may be provided, such as, e.g., one or more pressurized containers of oxygen gas. The inlets <NUM>, <NUM> separately receive the fuel and air from the external sources of fuel and air, and separately direct the fuel and air into the fuel cells.

In one embodiment, the air inlet side <NUM> and the outlet side <NUM> may be the only sides of the housing <NUM> that are not sealed. For example, the housing <NUM> may be sealed to prevent ingress or egress of fluids (gas and/or liquid) into and out of the housing <NUM>, but for the fuel and air inlets <NUM>, <NUM> and the combustion outlets <NUM>. The air and fuel that are directed into the housing <NUM> via the inlets <NUM>, <NUM> may be entirely or substantially consumed (e.g., at least <NUM>% of the volume or mass is consumed) by the fuel cells inside the housing <NUM> and/or the generation of combustion gas <NUM>. This can allow for the housing <NUM> to have no other outlet through which any fuel or air passes aside from the combustion outlets <NUM> through which the combustion gas <NUM> exits the housing <NUM>. According to one embodiment, partially oxidized fuel and unused air from the fuel cells inside the housing <NUM> can be directed into a combustor, such that the combustor combusts the partially oxidized fuel and air into one or more gaseous combustion products (e.g., exhaust), that are directed into and drive a downstream turbine (see, e.g., combustor <NUM> and turbine <NUM> of the gas turbine engine system <NUM> of the embodiment of <FIG>).

In one embodiment, the system <NUM> can be formed from one hundred fuel cells stacked side-by-side from the end or air inlet side <NUM> to the opposite side <NUM>. Alternatively, the system <NUM> can include fewer or more fuel cells stacked side-by-side. According to one embodiment, the system <NUM> can be eight centimeters tall, <NUM> centimeters wide, and twenty-four centimeters long. Alternatively, the system <NUM> can be taller or shorter, wider or narrower, and/or longer or shorter than these example dimensions.

According to one embodiment, the combination of the combustion system with an integrated fuel cell (i.e., the fuel cell and combustor system <NUM>) can be integrated into the liner of a combustor such that the combustor is circumferentially surrounded along some or all the length of the combustor by the housing <NUM> having a fuel cell stack or plurality of fuel cells. Thus, according to this embodiment, the system <NUM> or housing <NUM> directly abuts the combustor of, e.g., a gas turbine engine along the length of the combustor (see, e.g., combustor <NUM> of the gas turbine engine <NUM> of the embodiment of <FIG>). The housing <NUM> can form the outer surface or boundary of the combustor. This can include the housing <NUM> being integrally formed with the combustor. This arrangement reduces or eliminates the need to include additional ducting to fluidly couple the housing <NUM> with the combustor. According to another embodiment, the fuel cell stack can be axially coupled to the combustor, meaning the fuel cell stack is upstream of the combustor but not necessarily circumferentially surrounding the combustor.

According to one embodiment, the combustor is fluidly coupled with the housing <NUM> (see, e.g., combustor <NUM> of the gas turbine engine <NUM> of the embodiment of <FIG>). The combustor receives unspent fuel and air (e.g., combustion gas <NUM>) from the housing <NUM> along radially inward directions oriented toward an annular axis of the combustor (see, e.g., annular axis <NUM> of the combustor <NUM> of the embodiment of <FIG>).

According to one embodiment, fuel cells (e.g., SOFCs) within the housing <NUM> are positioned to receive (i) discharged air from a compressor and/or a pre-burner system as described further below and (ii) fuel from a source, such as, e.g., a catalytic partial oxidation convertor as described further below. The fuel cells within the housing <NUM> generate electrical current using this air and at least some of this fuel, and radially direct partially oxidized fuel and unused air into the combustor. The combustor combusts the partially oxidized fuel and air into one or more gaseous combustion products (e.g., exhaust), that can be directed into and drive a downstream turbine (see, e.g., combustor <NUM> and turbine <NUM> of the gas turbine engine <NUM> of the embodiment of <FIG>).

<FIG> illustrates a gas turbine engine having a combination of a combustion system with an integrated fuel cell according to one embodiment of the present disclosure. As shown in <FIG>, the gas turbine engine <NUM> includes an engine case <NUM> that encases a compressor <NUM>, a combustor <NUM> (e.g., a gas turbine combustor), and a fuel cell <NUM> and/or a fuel cell stack having a plurality of fuel cells (e.g., SOFCs) integrated with the combustor <NUM>. According to one embodiment, the fuel cell <NUM> (e.g., solid oxide fuel cell) is designed into the outer and/or inner liners of the combustor <NUM>. For example, according to one embodiment, the fuel cell <NUM> could be integrated into the combustor <NUM> according to the embodiment illustrated in <FIG>. Alternatively, according to another embodiment, the fuel cell <NUM> could comprise the system <NUM> with housing <NUM> illustrated in <FIG>, which is then integrated into the outer and/or inner liners of the combustor <NUM>. The fuel cell <NUM> can also be integrated into the outer and/or inner liners of the combustor <NUM> in another manner.

As shown in <FIG>, the engine <NUM> further includes a fuel source <NUM>, a pre-burner system <NUM>, and a catalytic partial oxidation (C-POX) convertor <NUM>. According to one embodiment, the pre-burner system <NUM> and the catalytic partial oxidation (C-POX) convertor <NUM> are manifolded together to provide conditioned air and fuel to a micromixer, such as, e.g., the fuel cell <NUM> (e.g., SOFC). According to an embodiment, the catalytic partial oxidation (C-POX) convertor <NUM>, the pre-burner system <NUM>, and the fuel cell <NUM> and/or fuel cell stack having a plurality of fuel cells (e.g., SOFCs) are closely coupled within the engine case <NUM> of the gas turbine engine <NUM> (or engine assembly), such that the catalytic partial oxidation (C-POX) convertor <NUM>, the pre-burner system <NUM>, and the fuel cell <NUM> and/or fuel cell stack are positioned as close as possible to each other within the engine case <NUM>. A portion of fuel <NUM> from the fuel source <NUM> is directed to the pre-burner system <NUM> for raising the temperature of air <NUM> that is discharged from the compressor <NUM> to, for example, an operating point of the fuel cell <NUM> and/or up to <NUM> less than and/or up to <NUM> more than the operating point of the fuel cell <NUM>, e.g., a temperature high enough to enable fuel cell temperature control (e.g., ~<NUM> to <NUM>), while another portion of fuel <NUM> from the fuel source <NUM> is directed to the catalytic partial oxidation (C-POX) convertor <NUM> for developing a hydrogen rich fuel stream. As the temperature of the air <NUM> that is discharged from the compressor <NUM> is raised to an operating point of the fuel cell <NUM> (e.g., <NUM> to <NUM>) and/or up to <NUM> less than and/or up to <NUM> more than the operating point of the fuel cell <NUM>, this heated air <NUM> is then directed into the fuel cell <NUM> to facilitate the functioning of the fuel cell <NUM> (e.g., SOFC) located in a liner region of the combustor <NUM>. In parallel, the portion of fuel <NUM> that is directed from the fuel source <NUM> into the catalytic partial oxidation convertor <NUM> is developed into a hydrogen rich fuel stream <NUM> that is also fed into the fuel cell <NUM>.

According to another embodiment, the fuel source <NUM> can comprise a hydrogen (H<NUM>) fuel, as opposed to (or in addition to) a hydrocarbon fuel source. According to this embodiment, the catalytic partial oxidation (C-POX) convertor <NUM> may not be necessary for this hydrogen (H<NUM>) fuel source, and thus, the hydrogen (H<NUM>) fuel stream (e.g., fuel stream <NUM>) can be sent directly into the fuel cell <NUM> (e.g., SOFC) that is designed into the outer and/or inner liners of the combustor <NUM>. According to one embodiment, when hydrogen (H<NUM>) fuel is the fuel source <NUM>, a heat-exchanger (not shown), a pre-burner system (e.g., pre-burner system <NUM>), and/or a catalytic partial oxidation (C-POX) convertor (e.g., catalytic partial oxidation (C-POX) convertor <NUM>) can be included to control the temperature of the hydrogen (H<NUM>) fuel to at least one of (i) an operating point of the fuel cell <NUM> (e.g., SOFC), (ii) up to <NUM> less than the operating point of the fuel cell <NUM> (e.g., SOFC), and (iii) up to <NUM> more than the operating point of the fuel cell <NUM> (e.g., SOFC).

As further shown in <FIG>, the combustor <NUM> also includes a pilot/main burner <NUM>. During operation, the pilot/main burner <NUM> is used to start the engine <NUM> and to increase the operating temperature, pressure, and mass flow of air. Once the engine <NUM> is sufficiently high in temperature, pressure, and mass flow of air, the portion of fuel <NUM> is diverted from the fuel source <NUM> to the catalytic partial oxidation convertor <NUM> and the other portion of fuel <NUM> is diverted from the fuel source <NUM> to the pre-burner system <NUM> to increase the temperature of the portion of air <NUM> that is discharged from the compressor <NUM> to, for example, an operating point of the fuel cell <NUM> (e.g., <NUM> to <NUM>) and/or up to <NUM> less than and/or up to <NUM> more than the operating point of the fuel cell <NUM> to facilitate the functioning of the fuel cell <NUM> (e.g., SOFC) located in the liner region of the combustor <NUM>, as discussed above. The hydrogen rich fuel stream <NUM> (i.e., a hydrogen and carbon monoxide stream) that is developed in the catalytic partial oxidation convertor <NUM> is utilized along with the air <NUM> that is heated by the pre-burner system <NUM> in the fuel cell <NUM> to generate electrical power. Unburned fuel and air <NUM> from the fuel cell <NUM> is channeled into the combustor <NUM> where a pilot/main flame from the pilot/main burner <NUM> is present and provides ignition to consume any unburned hydrogen and carbon monoxide effluents <NUM> from the fuel cell <NUM>. According to one embodiment, the exhausted fuel and air flow <NUM> from the fuel cell <NUM> (e.g., SOFC) is consumed in the combustor <NUM> like a micromixer burner. The heated air (e.g., exhaust) is then channeled into the gas turbine nozzle <NUM> for work extraction by the turbine (see, e.g., turbine <NUM> of the gas turbine engine <NUM> of the embodiment of <FIG>). According to another embodiment, one or more pilot/main fuel nozzles (e.g., pilot/main burner <NUM>) and/or injectors with a mixer and/or swirler are included within the combustor <NUM> that can aid in at least partially mixing air and fuel to facilitate combustion of fuel and air, the main/pilot flames being configured to combust the fuel directed into the combustor from the fuel cell stack into the one or more gaseous combustion products.

According to one embodiment of the present disclosure, by incorporating or integrating the fuel cell <NUM> (e.g., SOFC) along the combustor liner of the combustor <NUM> for a gas turbine engine <NUM> (e.g., an aircraft engine), in which a compressor <NUM> is connected upstream to the combustor <NUM> and a turbine (not shown) is connected downstream to the combustor <NUM>, both air and fuel can be directed to the fuel cell <NUM> (SOFC) in a single pass, meaning there is no recycling of the unburned fuel or air from the fuel cell exhaust to the inlet of the fuel cell <NUM>. Thus, there is no need for a separate air supply or any related control means in this configuration. However, because the inlet air for the fuel cell <NUM> (e.g., SOFC) comes solely from the upstream engine compressor <NUM> without any other separately controlled air source, the inlet air for the fuel cell <NUM> that is discharged from the compressor <NUM> is subject to the air temperature changes that occur at different flight stages. For example, the air within the aircraft engine compressor may work at <NUM> during idle, <NUM> during take-off, <NUM> during cruise, etc. This type of temperature change to the inlet air directed to the fuel cell may lead to significant thermal transient issues (or even thermal shock) to the ceramic materials of the fuel cell (e.g., SOFC), which could range from cracking to failure. Thus, according to embodiments of the present disclosure, by fluidly connecting the pre-burner system <NUM> to (i) the engine compressor <NUM> (at an upstream side to the pre-burner system <NUM>) and (ii) the fuel cell <NUM> (e.g., SOFC) (at a downstream side to the pre-burner system <NUM>), the pre-burner system <NUM> serves as a control means or system to maintain the air <NUM> being directed into the fuel cell <NUM> at a temperature at a desired range (e.g., <NUM> to <NUM> ±<NUM>). Furthermore, by integrating the pre-burner system <NUM> with the catalytic partial oxidation (C-POX) convertor <NUM>, a better thermal management with faster startup could be achieved. This further improves the system operability.

In one embodiment, the diversion of fuel (e.g., fuel portions <NUM>, <NUM>) from the fuel source <NUM> can be individually controlled to better manage the temperature of the air flow <NUM> being directed into the fuel cell <NUM>. For example, a controller (or control system) (e.g., hardware circuitry that includes and/or is coupled with one or more processors, such as microprocessors) can control valves which, in turn, control the flow of fuel to the pre-burner system <NUM> and/or the catalytic partial oxidation convertor <NUM>. The temperature of the air <NUM> that is discharged from the compressor <NUM> can be controlled by controlling the flow of fuel to the pre-burner system <NUM> via the controller. For example, the controller can close or open valves to decrease or to increase (respectively) the amount of fuel flowing into the pre-burner system <NUM>. The amount of fuel flowing into the pre-burner system <NUM> can be decreased to thereby decrease the temperature of the air <NUM> that is discharged from the compressor <NUM> and directed into the pre-burner system <NUM>, or can be increased to thereby increase the temperature of the air <NUM> that is discharged from the compressor <NUM> and directed into the pre-burner system <NUM>. Optionally, no fuel can be delivered to the pre-burner system <NUM> via the fuel source <NUM> to prevent the pre-burner system <NUM> from increasing and/or decreasing the temperature of the air <NUM> that is discharged from the compressor <NUM> and directed into the pre-burner system <NUM>.

<FIG> illustrates a flowchart of one embodiment of a method <NUM> of operating an integrated fuel cell and a combustor assembly. The method <NUM> can describe the operations performed in generating thrust and electrical current using the integrated fuel cell and combustor assemblies described herein (see, e.g., <FIG>, <FIG>, and <FIG>). At step <NUM>, air that is discharged from a compressor of an engine is heated to, for example, an operating point of the fuel cell (e.g., <NUM> to <NUM>) and/or up to <NUM> less than and/or up to <NUM> more than the operating point of the fuel cell by a pre-burner system. At step <NUM>, the heated or preheated air is output from the pre-burner system and into fuel cells of a fuel cell stack of the integrated fuel cell and combustor assembly. At step <NUM>, fuel is directed into the fuel cells of the integrated fuel cell and combustor assembly via a fuel source and/or a catalytic partial oxidation (C-POX) convertor. The direction of fuel into the fuel cells (at step <NUM>) and the flow of air into the fuel cells (at step <NUM>) can occur simultaneously, concurrently, sequentially, or in a reverse order than as shown in <FIG>.

At step <NUM>, the air and fuel in the fuel cells are at least partially converted into electrical energy. For example, the fuel cells can be connected in a series to build up a direct current that is created in the fuel cells. This current can be used to power a load, such as a fan of the engine or another load or used to charge a battery. At step <NUM>, effluent of the fuel cells is radially directed inward into the combustor and toward the annular axis of the combustor. The effluent can include unused air, unburned fuel, and/or other gaseous constituents of the fuel cells. At step <NUM>, the effluent is combusted (at least partially) in the combustor. Additional air from the compressor and/or fuel from fuel injectors can be directed into the combustor to aid with the combustion. The combustion in the combustor generates gaseous combustion products. At step <NUM>, a turbine of the engine is driven by the gaseous combustion products in the combustor. For example, exhaust from the combustor may be directed into the turbine to rotate the turbine.

Thus, in accordance with the principles of the disclosure, the arrangement of a pre-burner system upstream of a fuel cell (e.g., SOFC), but in parallel to a catalytic partial oxidation (C-POX) convertor that converts liquid fuel (such as, e.g., jet A or ethanol), such that (i) the pre-burner system feeds air heated to, for example, an operating point of the fuel cell (e.g., <NUM> to <NUM>) and/or up to <NUM> less than and/or up to <NUM> more than the operating point of the fuel cell into the cathode and anode sides of the fuel cell and (ii) the catalytic partial oxidation (C-POX) convertor feeds a hydrogen rich stream into the cathode and anode sides of the fuel cell, the effluents of which are dumped into a combustor and burned before being channeled to a gas turbine nozzle, is novel.

According to one embodiment of the present disclosure, a catalytic partial oxidation (C-POX) convertor, a pre-burner system, and a fuel cell (e.g., SOFC) are closely coupled within an engine (e.g., gas turbine engine).

According to one embodiment of the present disclosure, a catalytic partial oxidation (C-POX) convertor is included with a combination of a combustion system with an integrated fuel cell for a gas turbine engine to convert liquid fuel into a gaseous hydrogen/CO (carbon monoxide) stream.

According to one embodiment of the present disclosure, a fuel cell (e.g., SOFC) is closely coupled and/or integrated with a combustor, such that the exhaust of the fuel cell directly enters the combustor. Thus, according to embodiments of the present disclosure, there is no recycling of the unburned fuel from the fuel cell.

According to one embodiment of the present disclosure, a pilot/main burner or fuel nozzle along with a mixer within a combustor is used to initiate and maintain a flame that consumes unburned fuel from a fuel cell (e.g., SOFC). According to another embodiment, engine fuel flow is divided into two streams: (i) a first stream that is directed to the pilot burner of the combustor and (ii) a second stream that is directed to the fuel cell (e.g., SOFC) and/or a catalytic partial oxidation (C-POX) convertor.

According to one embodiment of the present disclosure, a control system is included to maintain an exit temperature of air of a pre-burner system at <NUM> to <NUM> at all operating conditions.

In accordance with the principles of the disclosure, a first challenge of maintaining air temperature to a fuel cell (e.g., SOFC) to, for example, an operating point of the fuel cell (e.g., <NUM> to <NUM>) and/or up to <NUM> less than and/or up to <NUM> more than the operating point of the fuel cell can be solved by including a combustion system (e.g., a pre-burner system) that consumes a small amount of fuel to enable control of the air temperature of air reaching the fuel cell.

In accordance with the principles of the disclosure, a second challenge of creating a mixture of hydrogen and carbon monoxide to enable a fuel cell to function can be solved by including a catalytic partial oxidation (C-POX) convertor that converts fuel ethanol with air to a stream containing hydrogen, carbon monoxide, and nitrogen.

In accordance with the principles of the disclosure, a third challenge of managing fuel that is injected into a fuel cell (e.g., SOFC), but is not consumed, can be solved by locating the fuel cell next to and/or within a gas turbine combustor having a pilot/main fuel nozzle in such a way that the effluents from the fuel cell, which contain unused fuel, are consumed in the gas turbine combustor thereby releasing heat and being fully converted to water and carbon dioxide.

In accordance with the principles of the disclosure, a combination of a combustion system with an integrated fuel cell can enable steady state and transient operation of a fuel cell (e.g., SOFC) as a topping cycle with a gas turbine engine (e.g., a Brayton cycle gas turbine engine) being the bottoming cycle. This combination provides increased efficiency in comparison with a conventional gas turbine engine (e.g., an advanced Brayton cycle gas turbine engine).

According to one embodiment of the present disclosure, depending on the design of the fuel cell (e.g., SOFC), the combustor, and the engine cycle, a topping cycle using the integrated combustor and fuel cell assembly according to embodiments of the present disclosure can provide from <NUM> KW to <NUM> KW topping electrical power in a gas turbine engine, increasing core efficiency by <NUM> to <NUM>% points.

Claim 1:
An engine assembly (<NUM>) for a gas turbine engine, comprising
(a) a combustor (<NUM>);
(b) a fuel cell stack (<NUM>) integrated with the combustor (<NUM>), the fuel cell stack (<NUM>) configured to direct fuel and air exhaust (<NUM>) from the fuel cell stack (<NUM>) into the combustor (<NUM>); and
(c) a pre-burner system (<NUM>) fluidly connected to the fuel cell stack (<NUM>), the pre-burner system (<NUM>) being configured to control a temperature of an air flow (<NUM>) directed into the fuel cell stack (<NUM>),
wherein the combustor (<NUM>) is configured to combust the fuel and air exhaust (<NUM>) from the fuel cell stack (<NUM>) into one or more gaseous combustion products that drive, in use, a downstream turbine (<NUM>),
the engine assembly further comprising a catalytic partial oxidation convertor (<NUM>) that is fluidly connected to the fuel cell stack (<NUM>), wherein the catalytic partial oxidation convertor (<NUM>) is configured to develop a hydrogen rich fuel stream (<NUM>) to be directed into the fuel cell stack (<NUM>),
the engine assembly further comprising a fuel source (<NUM>) that provides fuel and is fluidly connected to the pre-burner system (<NUM>) and the catalytic partial oxidation convertor (<NUM>), wherein (i) a first portion of the fuel (<NUM>) is directed from the fuel source (<NUM>) to the pre-burner system (<NUM>) to raise a temperature of a portion of air (<NUM>) directed, in use, into the pre-burner system (<NUM>) from a compressor (<NUM>), and (ii) a second portion of the fuel (<NUM>) is directed from the fuel source (<NUM>) to the catalytic partial oxidation convertor (<NUM>) for developing the hydrogen rich fuel stream (<NUM>).